clk: Remove forward declared function prototypes
authorStephen Boyd <sboyd@codeaurora.org>
Thu, 30 Apr 2015 21:43:22 +0000 (14:43 -0700)
committerStephen Boyd <sboyd@codeaurora.org>
Thu, 30 Apr 2015 23:28:39 +0000 (16:28 -0700)
Move the code around so that we don't need to declare function
prototypes at the start of the file. Simplify
clk_core_is_prepared() and clk_core_is_enabled() too to make the
diff easier to read.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
drivers/clk/clk.c

index 3e58b74530767c1530d819c4b8549ff3eeb618e1..0001b91f2b6e70b1c24d8854a5a59a55a57bf888 100644 (file)
@@ -37,13 +37,6 @@ static HLIST_HEAD(clk_root_list);
 static HLIST_HEAD(clk_orphan_list);
 static LIST_HEAD(clk_notifier_list);
 
-static long clk_core_get_accuracy(struct clk_core *core);
-static unsigned long clk_core_get_rate(struct clk_core *core);
-static int clk_core_get_phase(struct clk_core *core);
-static bool clk_core_is_prepared(struct clk_core *core);
-static bool clk_core_is_enabled(struct clk_core *core);
-static struct clk_core *clk_core_lookup(const char *name);
-
 /***    private data structures    ***/
 
 struct clk_core {
@@ -145,2093 +138,2075 @@ static void clk_enable_unlock(unsigned long flags)
        spin_unlock_irqrestore(&enable_lock, flags);
 }
 
-/***        debugfs support        ***/
-
-#ifdef CONFIG_DEBUG_FS
-#include <linux/debugfs.h>
+static bool clk_core_is_prepared(struct clk_core *core)
+{
+       /*
+        * .is_prepared is optional for clocks that can prepare
+        * fall back to software usage counter if it is missing
+        */
+       if (!core->ops->is_prepared)
+               return core->prepare_count;
 
-static struct dentry *rootdir;
-static int inited = 0;
-static DEFINE_MUTEX(clk_debug_lock);
-static HLIST_HEAD(clk_debug_list);
+       return core->ops->is_prepared(core->hw);
+}
 
-static struct hlist_head *all_lists[] = {
-       &clk_root_list,
-       &clk_orphan_list,
-       NULL,
-};
+static bool clk_core_is_enabled(struct clk_core *core)
+{
+       /*
+        * .is_enabled is only mandatory for clocks that gate
+        * fall back to software usage counter if .is_enabled is missing
+        */
+       if (!core->ops->is_enabled)
+               return core->enable_count;
 
-static struct hlist_head *orphan_list[] = {
-       &clk_orphan_list,
-       NULL,
-};
+       return core->ops->is_enabled(core->hw);
+}
 
-static void clk_summary_show_one(struct seq_file *s, struct clk_core *c,
-                                int level)
+/* caller must hold prepare_lock */
+static void clk_unprepare_unused_subtree(struct clk_core *core)
 {
-       if (!c)
+       struct clk_core *child;
+
+       lockdep_assert_held(&prepare_lock);
+
+       hlist_for_each_entry(child, &core->children, child_node)
+               clk_unprepare_unused_subtree(child);
+
+       if (core->prepare_count)
                return;
 
-       seq_printf(s, "%*s%-*s %11d %12d %11lu %10lu %-3d\n",
-                  level * 3 + 1, "",
-                  30 - level * 3, c->name,
-                  c->enable_count, c->prepare_count, clk_core_get_rate(c),
-                  clk_core_get_accuracy(c), clk_core_get_phase(c));
+       if (core->flags & CLK_IGNORE_UNUSED)
+               return;
+
+       if (clk_core_is_prepared(core)) {
+               trace_clk_unprepare(core);
+               if (core->ops->unprepare_unused)
+                       core->ops->unprepare_unused(core->hw);
+               else if (core->ops->unprepare)
+                       core->ops->unprepare(core->hw);
+               trace_clk_unprepare_complete(core);
+       }
 }
 
-static void clk_summary_show_subtree(struct seq_file *s, struct clk_core *c,
-                                    int level)
+/* caller must hold prepare_lock */
+static void clk_disable_unused_subtree(struct clk_core *core)
 {
        struct clk_core *child;
+       unsigned long flags;
 
-       if (!c)
-               return;
+       lockdep_assert_held(&prepare_lock);
 
-       clk_summary_show_one(s, c, level);
+       hlist_for_each_entry(child, &core->children, child_node)
+               clk_disable_unused_subtree(child);
 
-       hlist_for_each_entry(child, &c->children, child_node)
-               clk_summary_show_subtree(s, child, level + 1);
+       flags = clk_enable_lock();
+
+       if (core->enable_count)
+               goto unlock_out;
+
+       if (core->flags & CLK_IGNORE_UNUSED)
+               goto unlock_out;
+
+       /*
+        * some gate clocks have special needs during the disable-unused
+        * sequence.  call .disable_unused if available, otherwise fall
+        * back to .disable
+        */
+       if (clk_core_is_enabled(core)) {
+               trace_clk_disable(core);
+               if (core->ops->disable_unused)
+                       core->ops->disable_unused(core->hw);
+               else if (core->ops->disable)
+                       core->ops->disable(core->hw);
+               trace_clk_disable_complete(core);
+       }
+
+unlock_out:
+       clk_enable_unlock(flags);
 }
 
-static int clk_summary_show(struct seq_file *s, void *data)
+static bool clk_ignore_unused;
+static int __init clk_ignore_unused_setup(char *__unused)
 {
-       struct clk_core *c;
-       struct hlist_head **lists = (struct hlist_head **)s->private;
+       clk_ignore_unused = true;
+       return 1;
+}
+__setup("clk_ignore_unused", clk_ignore_unused_setup);
 
-       seq_puts(s, "   clock                         enable_cnt  prepare_cnt        rate   accuracy   phase\n");
-       seq_puts(s, "----------------------------------------------------------------------------------------\n");
+static int clk_disable_unused(void)
+{
+       struct clk_core *core;
+
+       if (clk_ignore_unused) {
+               pr_warn("clk: Not disabling unused clocks\n");
+               return 0;
+       }
 
        clk_prepare_lock();
 
-       for (; *lists; lists++)
-               hlist_for_each_entry(c, *lists, child_node)
-                       clk_summary_show_subtree(s, c, 0);
+       hlist_for_each_entry(core, &clk_root_list, child_node)
+               clk_disable_unused_subtree(core);
+
+       hlist_for_each_entry(core, &clk_orphan_list, child_node)
+               clk_disable_unused_subtree(core);
+
+       hlist_for_each_entry(core, &clk_root_list, child_node)
+               clk_unprepare_unused_subtree(core);
+
+       hlist_for_each_entry(core, &clk_orphan_list, child_node)
+               clk_unprepare_unused_subtree(core);
 
        clk_prepare_unlock();
 
        return 0;
 }
+late_initcall_sync(clk_disable_unused);
 
+/***    helper functions   ***/
 
-static int clk_summary_open(struct inode *inode, struct file *file)
+const char *__clk_get_name(struct clk *clk)
 {
-       return single_open(file, clk_summary_show, inode->i_private);
+       return !clk ? NULL : clk->core->name;
 }
+EXPORT_SYMBOL_GPL(__clk_get_name);
 
-static const struct file_operations clk_summary_fops = {
-       .open           = clk_summary_open,
-       .read           = seq_read,
-       .llseek         = seq_lseek,
-       .release        = single_release,
-};
+struct clk_hw *__clk_get_hw(struct clk *clk)
+{
+       return !clk ? NULL : clk->core->hw;
+}
+EXPORT_SYMBOL_GPL(__clk_get_hw);
 
-static void clk_dump_one(struct seq_file *s, struct clk_core *c, int level)
+u8 __clk_get_num_parents(struct clk *clk)
 {
-       if (!c)
-               return;
+       return !clk ? 0 : clk->core->num_parents;
+}
+EXPORT_SYMBOL_GPL(__clk_get_num_parents);
 
-       seq_printf(s, "\"%s\": { ", c->name);
-       seq_printf(s, "\"enable_count\": %d,", c->enable_count);
-       seq_printf(s, "\"prepare_count\": %d,", c->prepare_count);
-       seq_printf(s, "\"rate\": %lu", clk_core_get_rate(c));
-       seq_printf(s, "\"accuracy\": %lu", clk_core_get_accuracy(c));
-       seq_printf(s, "\"phase\": %d", clk_core_get_phase(c));
+struct clk *__clk_get_parent(struct clk *clk)
+{
+       if (!clk)
+               return NULL;
+
+       /* TODO: Create a per-user clk and change callers to call clk_put */
+       return !clk->core->parent ? NULL : clk->core->parent->hw->clk;
 }
+EXPORT_SYMBOL_GPL(__clk_get_parent);
 
-static void clk_dump_subtree(struct seq_file *s, struct clk_core *c, int level)
+static struct clk_core *__clk_lookup_subtree(const char *name,
+                                            struct clk_core *core)
 {
        struct clk_core *child;
+       struct clk_core *ret;
 
-       if (!c)
-               return;
-
-       clk_dump_one(s, c, level);
+       if (!strcmp(core->name, name))
+               return core;
 
-       hlist_for_each_entry(child, &c->children, child_node) {
-               seq_printf(s, ",");
-               clk_dump_subtree(s, child, level + 1);
+       hlist_for_each_entry(child, &core->children, child_node) {
+               ret = __clk_lookup_subtree(name, child);
+               if (ret)
+                       return ret;
        }
 
-       seq_printf(s, "}");
+       return NULL;
 }
 
-static int clk_dump(struct seq_file *s, void *data)
+static struct clk_core *clk_core_lookup(const char *name)
 {
-       struct clk_core *c;
-       bool first_node = true;
-       struct hlist_head **lists = (struct hlist_head **)s->private;
-
-       seq_printf(s, "{");
+       struct clk_core *root_clk;
+       struct clk_core *ret;
 
-       clk_prepare_lock();
+       if (!name)
+               return NULL;
 
-       for (; *lists; lists++) {
-               hlist_for_each_entry(c, *lists, child_node) {
-                       if (!first_node)
-                               seq_puts(s, ",");
-                       first_node = false;
-                       clk_dump_subtree(s, c, 0);
-               }
+       /* search the 'proper' clk tree first */
+       hlist_for_each_entry(root_clk, &clk_root_list, child_node) {
+               ret = __clk_lookup_subtree(name, root_clk);
+               if (ret)
+                       return ret;
        }
 
-       clk_prepare_unlock();
+       /* if not found, then search the orphan tree */
+       hlist_for_each_entry(root_clk, &clk_orphan_list, child_node) {
+               ret = __clk_lookup_subtree(name, root_clk);
+               if (ret)
+                       return ret;
+       }
 
-       seq_printf(s, "}");
-       return 0;
+       return NULL;
 }
 
-
-static int clk_dump_open(struct inode *inode, struct file *file)
+static struct clk_core *clk_core_get_parent_by_index(struct clk_core *core,
+                                                        u8 index)
 {
-       return single_open(file, clk_dump, inode->i_private);
+       if (!core || index >= core->num_parents)
+               return NULL;
+       else if (!core->parents)
+               return clk_core_lookup(core->parent_names[index]);
+       else if (!core->parents[index])
+               return core->parents[index] =
+                       clk_core_lookup(core->parent_names[index]);
+       else
+               return core->parents[index];
 }
 
-static const struct file_operations clk_dump_fops = {
-       .open           = clk_dump_open,
-       .read           = seq_read,
-       .llseek         = seq_lseek,
-       .release        = single_release,
-};
-
-static int clk_debug_create_one(struct clk_core *core, struct dentry *pdentry)
+struct clk *clk_get_parent_by_index(struct clk *clk, u8 index)
 {
-       struct dentry *d;
-       int ret = -ENOMEM;
+       struct clk_core *parent;
 
-       if (!core || !pdentry) {
-               ret = -EINVAL;
-               goto out;
-       }
+       if (!clk)
+               return NULL;
 
-       d = debugfs_create_dir(core->name, pdentry);
-       if (!d)
-               goto out;
-
-       core->dentry = d;
-
-       d = debugfs_create_u32("clk_rate", S_IRUGO, core->dentry,
-                       (u32 *)&core->rate);
-       if (!d)
-               goto err_out;
-
-       d = debugfs_create_u32("clk_accuracy", S_IRUGO, core->dentry,
-                       (u32 *)&core->accuracy);
-       if (!d)
-               goto err_out;
+       parent = clk_core_get_parent_by_index(clk->core, index);
 
-       d = debugfs_create_u32("clk_phase", S_IRUGO, core->dentry,
-                       (u32 *)&core->phase);
-       if (!d)
-               goto err_out;
+       return !parent ? NULL : parent->hw->clk;
+}
+EXPORT_SYMBOL_GPL(clk_get_parent_by_index);
 
-       d = debugfs_create_x32("clk_flags", S_IRUGO, core->dentry,
-                       (u32 *)&core->flags);
-       if (!d)
-               goto err_out;
+unsigned int __clk_get_enable_count(struct clk *clk)
+{
+       return !clk ? 0 : clk->core->enable_count;
+}
 
-       d = debugfs_create_u32("clk_prepare_count", S_IRUGO, core->dentry,
-                       (u32 *)&core->prepare_count);
-       if (!d)
-               goto err_out;
+static unsigned long clk_core_get_rate_nolock(struct clk_core *core)
+{
+       unsigned long ret;
 
-       d = debugfs_create_u32("clk_enable_count", S_IRUGO, core->dentry,
-                       (u32 *)&core->enable_count);
-       if (!d)
-               goto err_out;
+       if (!core) {
+               ret = 0;
+               goto out;
+       }
 
-       d = debugfs_create_u32("clk_notifier_count", S_IRUGO, core->dentry,
-                       (u32 *)&core->notifier_count);
-       if (!d)
-               goto err_out;
+       ret = core->rate;
 
-       if (core->ops->debug_init) {
-               ret = core->ops->debug_init(core->hw, core->dentry);
-               if (ret)
-                       goto err_out;
-       }
+       if (core->flags & CLK_IS_ROOT)
+               goto out;
 
-       ret = 0;
-       goto out;
+       if (!core->parent)
+               ret = 0;
 
-err_out:
-       debugfs_remove_recursive(core->dentry);
-       core->dentry = NULL;
 out:
        return ret;
 }
 
-/**
- * clk_debug_register - add a clk node to the debugfs clk tree
- * @core: the clk being added to the debugfs clk tree
- *
- * Dynamically adds a clk to the debugfs clk tree if debugfs has been
- * initialized.  Otherwise it bails out early since the debugfs clk tree
- * will be created lazily by clk_debug_init as part of a late_initcall.
- */
-static int clk_debug_register(struct clk_core *core)
+unsigned long __clk_get_rate(struct clk *clk)
 {
-       int ret = 0;
-
-       mutex_lock(&clk_debug_lock);
-       hlist_add_head(&core->debug_node, &clk_debug_list);
+       if (!clk)
+               return 0;
 
-       if (!inited)
-               goto unlock;
+       return clk_core_get_rate_nolock(clk->core);
+}
+EXPORT_SYMBOL_GPL(__clk_get_rate);
 
-       ret = clk_debug_create_one(core, rootdir);
-unlock:
-       mutex_unlock(&clk_debug_lock);
+static unsigned long __clk_get_accuracy(struct clk_core *core)
+{
+       if (!core)
+               return 0;
 
-       return ret;
+       return core->accuracy;
 }
 
- /**
- * clk_debug_unregister - remove a clk node from the debugfs clk tree
- * @core: the clk being removed from the debugfs clk tree
- *
- * Dynamically removes a clk and all it's children clk nodes from the
- * debugfs clk tree if clk->dentry points to debugfs created by
- * clk_debug_register in __clk_init.
- */
-static void clk_debug_unregister(struct clk_core *core)
+unsigned long __clk_get_flags(struct clk *clk)
 {
-       mutex_lock(&clk_debug_lock);
-       hlist_del_init(&core->debug_node);
-       debugfs_remove_recursive(core->dentry);
-       core->dentry = NULL;
-       mutex_unlock(&clk_debug_lock);
+       return !clk ? 0 : clk->core->flags;
 }
+EXPORT_SYMBOL_GPL(__clk_get_flags);
 
-struct dentry *clk_debugfs_add_file(struct clk_hw *hw, char *name, umode_t mode,
-                               void *data, const struct file_operations *fops)
+bool __clk_is_prepared(struct clk *clk)
 {
-       struct dentry *d = NULL;
-
-       if (hw->core->dentry)
-               d = debugfs_create_file(name, mode, hw->core->dentry, data,
-                                       fops);
+       if (!clk)
+               return false;
 
-       return d;
+       return clk_core_is_prepared(clk->core);
 }
-EXPORT_SYMBOL_GPL(clk_debugfs_add_file);
 
-/**
- * clk_debug_init - lazily create the debugfs clk tree visualization
- *
- * clks are often initialized very early during boot before memory can
- * be dynamically allocated and well before debugfs is setup.
- * clk_debug_init walks the clk tree hierarchy while holding
- * prepare_lock and creates the topology as part of a late_initcall,
- * thus insuring that clks initialized very early will still be
- * represented in the debugfs clk tree.  This function should only be
- * called once at boot-time, and all other clks added dynamically will
- * be done so with clk_debug_register.
- */
-static int __init clk_debug_init(void)
+bool __clk_is_enabled(struct clk *clk)
 {
-       struct clk_core *core;
-       struct dentry *d;
-
-       rootdir = debugfs_create_dir("clk", NULL);
+       if (!clk)
+               return false;
 
-       if (!rootdir)
-               return -ENOMEM;
+       return clk_core_is_enabled(clk->core);
+}
+EXPORT_SYMBOL_GPL(__clk_is_enabled);
 
-       d = debugfs_create_file("clk_summary", S_IRUGO, rootdir, &all_lists,
-                               &clk_summary_fops);
-       if (!d)
-               return -ENOMEM;
+static bool mux_is_better_rate(unsigned long rate, unsigned long now,
+                          unsigned long best, unsigned long flags)
+{
+       if (flags & CLK_MUX_ROUND_CLOSEST)
+               return abs(now - rate) < abs(best - rate);
 
-       d = debugfs_create_file("clk_dump", S_IRUGO, rootdir, &all_lists,
-                               &clk_dump_fops);
-       if (!d)
-               return -ENOMEM;
+       return now <= rate && now > best;
+}
 
-       d = debugfs_create_file("clk_orphan_summary", S_IRUGO, rootdir,
-                               &orphan_list, &clk_summary_fops);
-       if (!d)
-               return -ENOMEM;
+static long
+clk_mux_determine_rate_flags(struct clk_hw *hw, unsigned long rate,
+                            unsigned long min_rate,
+                            unsigned long max_rate,
+                            unsigned long *best_parent_rate,
+                            struct clk_hw **best_parent_p,
+                            unsigned long flags)
+{
+       struct clk_core *core = hw->core, *parent, *best_parent = NULL;
+       int i, num_parents;
+       unsigned long parent_rate, best = 0;
 
-       d = debugfs_create_file("clk_orphan_dump", S_IRUGO, rootdir,
-                               &orphan_list, &clk_dump_fops);
-       if (!d)
-               return -ENOMEM;
+       /* if NO_REPARENT flag set, pass through to current parent */
+       if (core->flags & CLK_SET_RATE_NO_REPARENT) {
+               parent = core->parent;
+               if (core->flags & CLK_SET_RATE_PARENT)
+                       best = __clk_determine_rate(parent ? parent->hw : NULL,
+                                                   rate, min_rate, max_rate);
+               else if (parent)
+                       best = clk_core_get_rate_nolock(parent);
+               else
+                       best = clk_core_get_rate_nolock(core);
+               goto out;
+       }
 
-       mutex_lock(&clk_debug_lock);
-       hlist_for_each_entry(core, &clk_debug_list, debug_node)
-               clk_debug_create_one(core, rootdir);
+       /* find the parent that can provide the fastest rate <= rate */
+       num_parents = core->num_parents;
+       for (i = 0; i < num_parents; i++) {
+               parent = clk_core_get_parent_by_index(core, i);
+               if (!parent)
+                       continue;
+               if (core->flags & CLK_SET_RATE_PARENT)
+                       parent_rate = __clk_determine_rate(parent->hw, rate,
+                                                          min_rate,
+                                                          max_rate);
+               else
+                       parent_rate = clk_core_get_rate_nolock(parent);
+               if (mux_is_better_rate(rate, parent_rate, best, flags)) {
+                       best_parent = parent;
+                       best = parent_rate;
+               }
+       }
 
-       inited = 1;
-       mutex_unlock(&clk_debug_lock);
+out:
+       if (best_parent)
+               *best_parent_p = best_parent->hw;
+       *best_parent_rate = best;
 
-       return 0;
-}
-late_initcall(clk_debug_init);
-#else
-static inline int clk_debug_register(struct clk_core *core) { return 0; }
-static inline void clk_debug_reparent(struct clk_core *core,
-                                     struct clk_core *new_parent)
-{
+       return best;
 }
-static inline void clk_debug_unregister(struct clk_core *core)
+
+struct clk *__clk_lookup(const char *name)
 {
+       struct clk_core *core = clk_core_lookup(name);
+
+       return !core ? NULL : core->hw->clk;
 }
-#endif
 
-/* caller must hold prepare_lock */
-static void clk_unprepare_unused_subtree(struct clk_core *core)
+static void clk_core_get_boundaries(struct clk_core *core,
+                                   unsigned long *min_rate,
+                                   unsigned long *max_rate)
 {
-       struct clk_core *child;
+       struct clk *clk_user;
 
-       lockdep_assert_held(&prepare_lock);
+       *min_rate = 0;
+       *max_rate = ULONG_MAX;
 
-       hlist_for_each_entry(child, &core->children, child_node)
-               clk_unprepare_unused_subtree(child);
+       hlist_for_each_entry(clk_user, &core->clks, clks_node)
+               *min_rate = max(*min_rate, clk_user->min_rate);
 
-       if (core->prepare_count)
-               return;
+       hlist_for_each_entry(clk_user, &core->clks, clks_node)
+               *max_rate = min(*max_rate, clk_user->max_rate);
+}
 
-       if (core->flags & CLK_IGNORE_UNUSED)
-               return;
-
-       if (clk_core_is_prepared(core)) {
-               trace_clk_unprepare(core);
-               if (core->ops->unprepare_unused)
-                       core->ops->unprepare_unused(core->hw);
-               else if (core->ops->unprepare)
-                       core->ops->unprepare(core->hw);
-               trace_clk_unprepare_complete(core);
-       }
+/*
+ * Helper for finding best parent to provide a given frequency. This can be used
+ * directly as a determine_rate callback (e.g. for a mux), or from a more
+ * complex clock that may combine a mux with other operations.
+ */
+long __clk_mux_determine_rate(struct clk_hw *hw, unsigned long rate,
+                             unsigned long min_rate,
+                             unsigned long max_rate,
+                             unsigned long *best_parent_rate,
+                             struct clk_hw **best_parent_p)
+{
+       return clk_mux_determine_rate_flags(hw, rate, min_rate, max_rate,
+                                           best_parent_rate,
+                                           best_parent_p, 0);
 }
+EXPORT_SYMBOL_GPL(__clk_mux_determine_rate);
 
-/* caller must hold prepare_lock */
-static void clk_disable_unused_subtree(struct clk_core *core)
+long __clk_mux_determine_rate_closest(struct clk_hw *hw, unsigned long rate,
+                             unsigned long min_rate,
+                             unsigned long max_rate,
+                             unsigned long *best_parent_rate,
+                             struct clk_hw **best_parent_p)
 {
-       struct clk_core *child;
-       unsigned long flags;
+       return clk_mux_determine_rate_flags(hw, rate, min_rate, max_rate,
+                                           best_parent_rate,
+                                           best_parent_p,
+                                           CLK_MUX_ROUND_CLOSEST);
+}
+EXPORT_SYMBOL_GPL(__clk_mux_determine_rate_closest);
 
-       lockdep_assert_held(&prepare_lock);
+/***        clk api        ***/
 
-       hlist_for_each_entry(child, &core->children, child_node)
-               clk_disable_unused_subtree(child);
+static void clk_core_unprepare(struct clk_core *core)
+{
+       if (!core)
+               return;
 
-       flags = clk_enable_lock();
+       if (WARN_ON(core->prepare_count == 0))
+               return;
 
-       if (core->enable_count)
-               goto unlock_out;
+       if (--core->prepare_count > 0)
+               return;
 
-       if (core->flags & CLK_IGNORE_UNUSED)
-               goto unlock_out;
+       WARN_ON(core->enable_count > 0);
 
-       /*
-        * some gate clocks have special needs during the disable-unused
-        * sequence.  call .disable_unused if available, otherwise fall
-        * back to .disable
-        */
-       if (clk_core_is_enabled(core)) {
-               trace_clk_disable(core);
-               if (core->ops->disable_unused)
-                       core->ops->disable_unused(core->hw);
-               else if (core->ops->disable)
-                       core->ops->disable(core->hw);
-               trace_clk_disable_complete(core);
-       }
+       trace_clk_unprepare(core);
 
-unlock_out:
-       clk_enable_unlock(flags);
+       if (core->ops->unprepare)
+               core->ops->unprepare(core->hw);
+
+       trace_clk_unprepare_complete(core);
+       clk_core_unprepare(core->parent);
 }
 
-static bool clk_ignore_unused;
-static int __init clk_ignore_unused_setup(char *__unused)
+/**
+ * clk_unprepare - undo preparation of a clock source
+ * @clk: the clk being unprepared
+ *
+ * clk_unprepare may sleep, which differentiates it from clk_disable.  In a
+ * simple case, clk_unprepare can be used instead of clk_disable to gate a clk
+ * if the operation may sleep.  One example is a clk which is accessed over
+ * I2c.  In the complex case a clk gate operation may require a fast and a slow
+ * part.  It is this reason that clk_unprepare and clk_disable are not mutually
+ * exclusive.  In fact clk_disable must be called before clk_unprepare.
+ */
+void clk_unprepare(struct clk *clk)
 {
-       clk_ignore_unused = true;
-       return 1;
+       if (IS_ERR_OR_NULL(clk))
+               return;
+
+       clk_prepare_lock();
+       clk_core_unprepare(clk->core);
+       clk_prepare_unlock();
 }
-__setup("clk_ignore_unused", clk_ignore_unused_setup);
+EXPORT_SYMBOL_GPL(clk_unprepare);
 
-static int clk_disable_unused(void)
+static int clk_core_prepare(struct clk_core *core)
 {
-       struct clk_core *core;
+       int ret = 0;
 
-       if (clk_ignore_unused) {
-               pr_warn("clk: Not disabling unused clocks\n");
+       if (!core)
                return 0;
-       }
 
-       clk_prepare_lock();
+       if (core->prepare_count == 0) {
+               ret = clk_core_prepare(core->parent);
+               if (ret)
+                       return ret;
 
-       hlist_for_each_entry(core, &clk_root_list, child_node)
-               clk_disable_unused_subtree(core);
+               trace_clk_prepare(core);
 
-       hlist_for_each_entry(core, &clk_orphan_list, child_node)
-               clk_disable_unused_subtree(core);
+               if (core->ops->prepare)
+                       ret = core->ops->prepare(core->hw);
 
-       hlist_for_each_entry(core, &clk_root_list, child_node)
-               clk_unprepare_unused_subtree(core);
+               trace_clk_prepare_complete(core);
 
-       hlist_for_each_entry(core, &clk_orphan_list, child_node)
-               clk_unprepare_unused_subtree(core);
+               if (ret) {
+                       clk_core_unprepare(core->parent);
+                       return ret;
+               }
+       }
 
-       clk_prepare_unlock();
+       core->prepare_count++;
 
        return 0;
 }
-late_initcall_sync(clk_disable_unused);
-
-/***    helper functions   ***/
 
-const char *__clk_get_name(struct clk *clk)
+/**
+ * clk_prepare - prepare a clock source
+ * @clk: the clk being prepared
+ *
+ * clk_prepare may sleep, which differentiates it from clk_enable.  In a simple
+ * case, clk_prepare can be used instead of clk_enable to ungate a clk if the
+ * operation may sleep.  One example is a clk which is accessed over I2c.  In
+ * the complex case a clk ungate operation may require a fast and a slow part.
+ * It is this reason that clk_prepare and clk_enable are not mutually
+ * exclusive.  In fact clk_prepare must be called before clk_enable.
+ * Returns 0 on success, -EERROR otherwise.
+ */
+int clk_prepare(struct clk *clk)
 {
-       return !clk ? NULL : clk->core->name;
-}
-EXPORT_SYMBOL_GPL(__clk_get_name);
+       int ret;
 
-struct clk_hw *__clk_get_hw(struct clk *clk)
-{
-       return !clk ? NULL : clk->core->hw;
-}
-EXPORT_SYMBOL_GPL(__clk_get_hw);
+       if (!clk)
+               return 0;
 
-u8 __clk_get_num_parents(struct clk *clk)
-{
-       return !clk ? 0 : clk->core->num_parents;
+       clk_prepare_lock();
+       ret = clk_core_prepare(clk->core);
+       clk_prepare_unlock();
+
+       return ret;
 }
-EXPORT_SYMBOL_GPL(__clk_get_num_parents);
+EXPORT_SYMBOL_GPL(clk_prepare);
 
-struct clk *__clk_get_parent(struct clk *clk)
+static void clk_core_disable(struct clk_core *core)
 {
-       if (!clk)
-               return NULL;
+       if (!core)
+               return;
 
-       /* TODO: Create a per-user clk and change callers to call clk_put */
-       return !clk->core->parent ? NULL : clk->core->parent->hw->clk;
-}
-EXPORT_SYMBOL_GPL(__clk_get_parent);
+       if (WARN_ON(core->enable_count == 0))
+               return;
 
-static struct clk_core *clk_core_get_parent_by_index(struct clk_core *core,
-                                                        u8 index)
-{
-       if (!core || index >= core->num_parents)
-               return NULL;
-       else if (!core->parents)
-               return clk_core_lookup(core->parent_names[index]);
-       else if (!core->parents[index])
-               return core->parents[index] =
-                       clk_core_lookup(core->parent_names[index]);
-       else
-               return core->parents[index];
-}
+       if (--core->enable_count > 0)
+               return;
 
-struct clk *clk_get_parent_by_index(struct clk *clk, u8 index)
-{
-       struct clk_core *parent;
+       trace_clk_disable(core);
 
-       if (!clk)
-               return NULL;
+       if (core->ops->disable)
+               core->ops->disable(core->hw);
 
-       parent = clk_core_get_parent_by_index(clk->core, index);
+       trace_clk_disable_complete(core);
 
-       return !parent ? NULL : parent->hw->clk;
+       clk_core_disable(core->parent);
 }
-EXPORT_SYMBOL_GPL(clk_get_parent_by_index);
 
-unsigned int __clk_get_enable_count(struct clk *clk)
+/**
+ * clk_disable - gate a clock
+ * @clk: the clk being gated
+ *
+ * clk_disable must not sleep, which differentiates it from clk_unprepare.  In
+ * a simple case, clk_disable can be used instead of clk_unprepare to gate a
+ * clk if the operation is fast and will never sleep.  One example is a
+ * SoC-internal clk which is controlled via simple register writes.  In the
+ * complex case a clk gate operation may require a fast and a slow part.  It is
+ * this reason that clk_unprepare and clk_disable are not mutually exclusive.
+ * In fact clk_disable must be called before clk_unprepare.
+ */
+void clk_disable(struct clk *clk)
 {
-       return !clk ? 0 : clk->core->enable_count;
+       unsigned long flags;
+
+       if (IS_ERR_OR_NULL(clk))
+               return;
+
+       flags = clk_enable_lock();
+       clk_core_disable(clk->core);
+       clk_enable_unlock(flags);
 }
+EXPORT_SYMBOL_GPL(clk_disable);
 
-static unsigned long clk_core_get_rate_nolock(struct clk_core *core)
+static int clk_core_enable(struct clk_core *core)
 {
-       unsigned long ret;
+       int ret = 0;
 
-       if (!core) {
-               ret = 0;
-               goto out;
-       }
+       if (!core)
+               return 0;
 
-       ret = core->rate;
+       if (WARN_ON(core->prepare_count == 0))
+               return -ESHUTDOWN;
 
-       if (core->flags & CLK_IS_ROOT)
-               goto out;
+       if (core->enable_count == 0) {
+               ret = clk_core_enable(core->parent);
 
-       if (!core->parent)
-               ret = 0;
+               if (ret)
+                       return ret;
 
-out:
-       return ret;
-}
+               trace_clk_enable(core);
 
-unsigned long __clk_get_rate(struct clk *clk)
-{
-       if (!clk)
-               return 0;
+               if (core->ops->enable)
+                       ret = core->ops->enable(core->hw);
 
-       return clk_core_get_rate_nolock(clk->core);
+               trace_clk_enable_complete(core);
+
+               if (ret) {
+                       clk_core_disable(core->parent);
+                       return ret;
+               }
+       }
+
+       core->enable_count++;
+       return 0;
 }
-EXPORT_SYMBOL_GPL(__clk_get_rate);
 
-static unsigned long __clk_get_accuracy(struct clk_core *core)
+/**
+ * clk_enable - ungate a clock
+ * @clk: the clk being ungated
+ *
+ * clk_enable must not sleep, which differentiates it from clk_prepare.  In a
+ * simple case, clk_enable can be used instead of clk_prepare to ungate a clk
+ * if the operation will never sleep.  One example is a SoC-internal clk which
+ * is controlled via simple register writes.  In the complex case a clk ungate
+ * operation may require a fast and a slow part.  It is this reason that
+ * clk_enable and clk_prepare are not mutually exclusive.  In fact clk_prepare
+ * must be called before clk_enable.  Returns 0 on success, -EERROR
+ * otherwise.
+ */
+int clk_enable(struct clk *clk)
 {
-       if (!core)
+       unsigned long flags;
+       int ret;
+
+       if (!clk)
                return 0;
 
-       return core->accuracy;
-}
+       flags = clk_enable_lock();
+       ret = clk_core_enable(clk->core);
+       clk_enable_unlock(flags);
 
-unsigned long __clk_get_flags(struct clk *clk)
-{
-       return !clk ? 0 : clk->core->flags;
+       return ret;
 }
-EXPORT_SYMBOL_GPL(__clk_get_flags);
+EXPORT_SYMBOL_GPL(clk_enable);
 
-static bool clk_core_is_prepared(struct clk_core *core)
+static unsigned long clk_core_round_rate_nolock(struct clk_core *core,
+                                               unsigned long rate,
+                                               unsigned long min_rate,
+                                               unsigned long max_rate)
 {
-       int ret;
+       unsigned long parent_rate = 0;
+       struct clk_core *parent;
+       struct clk_hw *parent_hw;
+
+       lockdep_assert_held(&prepare_lock);
 
        if (!core)
-               return false;
+               return 0;
 
-       /*
-        * .is_prepared is optional for clocks that can prepare
-        * fall back to software usage counter if it is missing
-        */
-       if (!core->ops->is_prepared) {
-               ret = core->prepare_count ? 1 : 0;
-               goto out;
-       }
+       parent = core->parent;
+       if (parent)
+               parent_rate = parent->rate;
 
-       ret = core->ops->is_prepared(core->hw);
-out:
-       return !!ret;
+       if (core->ops->determine_rate) {
+               parent_hw = parent ? parent->hw : NULL;
+               return core->ops->determine_rate(core->hw, rate,
+                                               min_rate, max_rate,
+                                               &parent_rate, &parent_hw);
+       } else if (core->ops->round_rate)
+               return core->ops->round_rate(core->hw, rate, &parent_rate);
+       else if (core->flags & CLK_SET_RATE_PARENT)
+               return clk_core_round_rate_nolock(core->parent, rate, min_rate,
+                                                 max_rate);
+       else
+               return core->rate;
 }
 
-bool __clk_is_prepared(struct clk *clk)
+/**
+ * __clk_determine_rate - get the closest rate actually supported by a clock
+ * @hw: determine the rate of this clock
+ * @rate: target rate
+ * @min_rate: returned rate must be greater than this rate
+ * @max_rate: returned rate must be less than this rate
+ *
+ * Caller must hold prepare_lock.  Useful for clk_ops such as .set_rate and
+ * .determine_rate.
+ */
+unsigned long __clk_determine_rate(struct clk_hw *hw,
+                                  unsigned long rate,
+                                  unsigned long min_rate,
+                                  unsigned long max_rate)
 {
-       if (!clk)
-               return false;
+       if (!hw)
+               return 0;
 
-       return clk_core_is_prepared(clk->core);
+       return clk_core_round_rate_nolock(hw->core, rate, min_rate, max_rate);
 }
+EXPORT_SYMBOL_GPL(__clk_determine_rate);
 
-static bool clk_core_is_enabled(struct clk_core *core)
+/**
+ * __clk_round_rate - round the given rate for a clk
+ * @clk: round the rate of this clock
+ * @rate: the rate which is to be rounded
+ *
+ * Caller must hold prepare_lock.  Useful for clk_ops such as .set_rate
+ */
+unsigned long __clk_round_rate(struct clk *clk, unsigned long rate)
 {
-       int ret;
+       unsigned long min_rate;
+       unsigned long max_rate;
 
-       if (!core)
-               return false;
+       if (!clk)
+               return 0;
 
-       /*
-        * .is_enabled is only mandatory for clocks that gate
-        * fall back to software usage counter if .is_enabled is missing
-        */
-       if (!core->ops->is_enabled) {
-               ret = core->enable_count ? 1 : 0;
-               goto out;
-       }
+       clk_core_get_boundaries(clk->core, &min_rate, &max_rate);
 
-       ret = core->ops->is_enabled(core->hw);
-out:
-       return !!ret;
+       return clk_core_round_rate_nolock(clk->core, rate, min_rate, max_rate);
 }
+EXPORT_SYMBOL_GPL(__clk_round_rate);
 
-bool __clk_is_enabled(struct clk *clk)
+/**
+ * clk_round_rate - round the given rate for a clk
+ * @clk: the clk for which we are rounding a rate
+ * @rate: the rate which is to be rounded
+ *
+ * Takes in a rate as input and rounds it to a rate that the clk can actually
+ * use which is then returned.  If clk doesn't support round_rate operation
+ * then the parent rate is returned.
+ */
+long clk_round_rate(struct clk *clk, unsigned long rate)
 {
+       unsigned long ret;
+
        if (!clk)
-               return false;
+               return 0;
 
-       return clk_core_is_enabled(clk->core);
+       clk_prepare_lock();
+       ret = __clk_round_rate(clk, rate);
+       clk_prepare_unlock();
+
+       return ret;
 }
-EXPORT_SYMBOL_GPL(__clk_is_enabled);
+EXPORT_SYMBOL_GPL(clk_round_rate);
 
-static struct clk_core *__clk_lookup_subtree(const char *name,
-                                            struct clk_core *core)
+/**
+ * __clk_notify - call clk notifier chain
+ * @core: clk that is changing rate
+ * @msg: clk notifier type (see include/linux/clk.h)
+ * @old_rate: old clk rate
+ * @new_rate: new clk rate
+ *
+ * Triggers a notifier call chain on the clk rate-change notification
+ * for 'clk'.  Passes a pointer to the struct clk and the previous
+ * and current rates to the notifier callback.  Intended to be called by
+ * internal clock code only.  Returns NOTIFY_DONE from the last driver
+ * called if all went well, or NOTIFY_STOP or NOTIFY_BAD immediately if
+ * a driver returns that.
+ */
+static int __clk_notify(struct clk_core *core, unsigned long msg,
+               unsigned long old_rate, unsigned long new_rate)
 {
-       struct clk_core *child;
-       struct clk_core *ret;
+       struct clk_notifier *cn;
+       struct clk_notifier_data cnd;
+       int ret = NOTIFY_DONE;
 
-       if (!strcmp(core->name, name))
-               return core;
+       cnd.old_rate = old_rate;
+       cnd.new_rate = new_rate;
 
-       hlist_for_each_entry(child, &core->children, child_node) {
-               ret = __clk_lookup_subtree(name, child);
-               if (ret)
-                       return ret;
+       list_for_each_entry(cn, &clk_notifier_list, node) {
+               if (cn->clk->core == core) {
+                       cnd.clk = cn->clk;
+                       ret = srcu_notifier_call_chain(&cn->notifier_head, msg,
+                                       &cnd);
+               }
        }
 
-       return NULL;
+       return ret;
 }
 
-static struct clk_core *clk_core_lookup(const char *name)
+/**
+ * __clk_recalc_accuracies
+ * @core: first clk in the subtree
+ *
+ * Walks the subtree of clks starting with clk and recalculates accuracies as
+ * it goes.  Note that if a clk does not implement the .recalc_accuracy
+ * callback then it is assumed that the clock will take on the accuracy of it's
+ * parent.
+ *
+ * Caller must hold prepare_lock.
+ */
+static void __clk_recalc_accuracies(struct clk_core *core)
 {
-       struct clk_core *root_clk;
-       struct clk_core *ret;
+       unsigned long parent_accuracy = 0;
+       struct clk_core *child;
 
-       if (!name)
-               return NULL;
+       lockdep_assert_held(&prepare_lock);
 
-       /* search the 'proper' clk tree first */
-       hlist_for_each_entry(root_clk, &clk_root_list, child_node) {
-               ret = __clk_lookup_subtree(name, root_clk);
-               if (ret)
-                       return ret;
-       }
+       if (core->parent)
+               parent_accuracy = core->parent->accuracy;
 
-       /* if not found, then search the orphan tree */
-       hlist_for_each_entry(root_clk, &clk_orphan_list, child_node) {
-               ret = __clk_lookup_subtree(name, root_clk);
-               if (ret)
-                       return ret;
-       }
+       if (core->ops->recalc_accuracy)
+               core->accuracy = core->ops->recalc_accuracy(core->hw,
+                                                         parent_accuracy);
+       else
+               core->accuracy = parent_accuracy;
 
-       return NULL;
+       hlist_for_each_entry(child, &core->children, child_node)
+               __clk_recalc_accuracies(child);
 }
 
-static bool mux_is_better_rate(unsigned long rate, unsigned long now,
-                          unsigned long best, unsigned long flags)
+static long clk_core_get_accuracy(struct clk_core *core)
 {
-       if (flags & CLK_MUX_ROUND_CLOSEST)
-               return abs(now - rate) < abs(best - rate);
+       unsigned long accuracy;
 
-       return now <= rate && now > best;
-}
+       clk_prepare_lock();
+       if (core && (core->flags & CLK_GET_ACCURACY_NOCACHE))
+               __clk_recalc_accuracies(core);
 
-static long
-clk_mux_determine_rate_flags(struct clk_hw *hw, unsigned long rate,
-                            unsigned long min_rate,
-                            unsigned long max_rate,
-                            unsigned long *best_parent_rate,
-                            struct clk_hw **best_parent_p,
-                            unsigned long flags)
-{
-       struct clk_core *core = hw->core, *parent, *best_parent = NULL;
-       int i, num_parents;
-       unsigned long parent_rate, best = 0;
-
-       /* if NO_REPARENT flag set, pass through to current parent */
-       if (core->flags & CLK_SET_RATE_NO_REPARENT) {
-               parent = core->parent;
-               if (core->flags & CLK_SET_RATE_PARENT)
-                       best = __clk_determine_rate(parent ? parent->hw : NULL,
-                                                   rate, min_rate, max_rate);
-               else if (parent)
-                       best = clk_core_get_rate_nolock(parent);
-               else
-                       best = clk_core_get_rate_nolock(core);
-               goto out;
-       }
-
-       /* find the parent that can provide the fastest rate <= rate */
-       num_parents = core->num_parents;
-       for (i = 0; i < num_parents; i++) {
-               parent = clk_core_get_parent_by_index(core, i);
-               if (!parent)
-                       continue;
-               if (core->flags & CLK_SET_RATE_PARENT)
-                       parent_rate = __clk_determine_rate(parent->hw, rate,
-                                                          min_rate,
-                                                          max_rate);
-               else
-                       parent_rate = clk_core_get_rate_nolock(parent);
-               if (mux_is_better_rate(rate, parent_rate, best, flags)) {
-                       best_parent = parent;
-                       best = parent_rate;
-               }
-       }
-
-out:
-       if (best_parent)
-               *best_parent_p = best_parent->hw;
-       *best_parent_rate = best;
+       accuracy = __clk_get_accuracy(core);
+       clk_prepare_unlock();
 
-       return best;
+       return accuracy;
 }
 
-struct clk *__clk_lookup(const char *name)
+/**
+ * clk_get_accuracy - return the accuracy of clk
+ * @clk: the clk whose accuracy is being returned
+ *
+ * Simply returns the cached accuracy of the clk, unless
+ * CLK_GET_ACCURACY_NOCACHE flag is set, which means a recalc_rate will be
+ * issued.
+ * If clk is NULL then returns 0.
+ */
+long clk_get_accuracy(struct clk *clk)
 {
-       struct clk_core *core = clk_core_lookup(name);
+       if (!clk)
+               return 0;
 
-       return !core ? NULL : core->hw->clk;
+       return clk_core_get_accuracy(clk->core);
 }
+EXPORT_SYMBOL_GPL(clk_get_accuracy);
 
-static void clk_core_get_boundaries(struct clk_core *core,
-                                   unsigned long *min_rate,
-                                   unsigned long *max_rate)
+static unsigned long clk_recalc(struct clk_core *core,
+                               unsigned long parent_rate)
 {
-       struct clk *clk_user;
-
-       *min_rate = 0;
-       *max_rate = ULONG_MAX;
-
-       hlist_for_each_entry(clk_user, &core->clks, clks_node)
-               *min_rate = max(*min_rate, clk_user->min_rate);
-
-       hlist_for_each_entry(clk_user, &core->clks, clks_node)
-               *max_rate = min(*max_rate, clk_user->max_rate);
+       if (core->ops->recalc_rate)
+               return core->ops->recalc_rate(core->hw, parent_rate);
+       return parent_rate;
 }
 
-/*
- * Helper for finding best parent to provide a given frequency. This can be used
- * directly as a determine_rate callback (e.g. for a mux), or from a more
- * complex clock that may combine a mux with other operations.
+/**
+ * __clk_recalc_rates
+ * @core: first clk in the subtree
+ * @msg: notification type (see include/linux/clk.h)
+ *
+ * Walks the subtree of clks starting with clk and recalculates rates as it
+ * goes.  Note that if a clk does not implement the .recalc_rate callback then
+ * it is assumed that the clock will take on the rate of its parent.
+ *
+ * clk_recalc_rates also propagates the POST_RATE_CHANGE notification,
+ * if necessary.
+ *
+ * Caller must hold prepare_lock.
  */
-long __clk_mux_determine_rate(struct clk_hw *hw, unsigned long rate,
-                             unsigned long min_rate,
-                             unsigned long max_rate,
-                             unsigned long *best_parent_rate,
-                             struct clk_hw **best_parent_p)
+static void __clk_recalc_rates(struct clk_core *core, unsigned long msg)
 {
-       return clk_mux_determine_rate_flags(hw, rate, min_rate, max_rate,
-                                           best_parent_rate,
-                                           best_parent_p, 0);
-}
-EXPORT_SYMBOL_GPL(__clk_mux_determine_rate);
+       unsigned long old_rate;
+       unsigned long parent_rate = 0;
+       struct clk_core *child;
 
-long __clk_mux_determine_rate_closest(struct clk_hw *hw, unsigned long rate,
-                             unsigned long min_rate,
-                             unsigned long max_rate,
-                             unsigned long *best_parent_rate,
-                             struct clk_hw **best_parent_p)
-{
-       return clk_mux_determine_rate_flags(hw, rate, min_rate, max_rate,
-                                           best_parent_rate,
-                                           best_parent_p,
-                                           CLK_MUX_ROUND_CLOSEST);
-}
-EXPORT_SYMBOL_GPL(__clk_mux_determine_rate_closest);
+       lockdep_assert_held(&prepare_lock);
 
-/***        clk api        ***/
+       old_rate = core->rate;
 
-static void clk_core_unprepare(struct clk_core *core)
-{
-       if (!core)
-               return;
+       if (core->parent)
+               parent_rate = core->parent->rate;
 
-       if (WARN_ON(core->prepare_count == 0))
-               return;
+       core->rate = clk_recalc(core, parent_rate);
 
-       if (--core->prepare_count > 0)
-               return;
+       /*
+        * ignore NOTIFY_STOP and NOTIFY_BAD return values for POST_RATE_CHANGE
+        * & ABORT_RATE_CHANGE notifiers
+        */
+       if (core->notifier_count && msg)
+               __clk_notify(core, msg, old_rate, core->rate);
 
-       WARN_ON(core->enable_count > 0);
+       hlist_for_each_entry(child, &core->children, child_node)
+               __clk_recalc_rates(child, msg);
+}
 
-       trace_clk_unprepare(core);
+static unsigned long clk_core_get_rate(struct clk_core *core)
+{
+       unsigned long rate;
 
-       if (core->ops->unprepare)
-               core->ops->unprepare(core->hw);
+       clk_prepare_lock();
 
-       trace_clk_unprepare_complete(core);
-       clk_core_unprepare(core->parent);
+       if (core && (core->flags & CLK_GET_RATE_NOCACHE))
+               __clk_recalc_rates(core, 0);
+
+       rate = clk_core_get_rate_nolock(core);
+       clk_prepare_unlock();
+
+       return rate;
 }
 
 /**
- * clk_unprepare - undo preparation of a clock source
- * @clk: the clk being unprepared
+ * clk_get_rate - return the rate of clk
+ * @clk: the clk whose rate is being returned
  *
- * clk_unprepare may sleep, which differentiates it from clk_disable.  In a
- * simple case, clk_unprepare can be used instead of clk_disable to gate a clk
- * if the operation may sleep.  One example is a clk which is accessed over
- * I2c.  In the complex case a clk gate operation may require a fast and a slow
- * part.  It is this reason that clk_unprepare and clk_disable are not mutually
- * exclusive.  In fact clk_disable must be called before clk_unprepare.
+ * Simply returns the cached rate of the clk, unless CLK_GET_RATE_NOCACHE flag
+ * is set, which means a recalc_rate will be issued.
+ * If clk is NULL then returns 0.
  */
-void clk_unprepare(struct clk *clk)
+unsigned long clk_get_rate(struct clk *clk)
 {
-       if (IS_ERR_OR_NULL(clk))
-               return;
+       if (!clk)
+               return 0;
 
-       clk_prepare_lock();
-       clk_core_unprepare(clk->core);
-       clk_prepare_unlock();
+       return clk_core_get_rate(clk->core);
 }
-EXPORT_SYMBOL_GPL(clk_unprepare);
+EXPORT_SYMBOL_GPL(clk_get_rate);
 
-static int clk_core_prepare(struct clk_core *core)
+static int clk_fetch_parent_index(struct clk_core *core,
+                                 struct clk_core *parent)
 {
-       int ret = 0;
-
-       if (!core)
-               return 0;
-
-       if (core->prepare_count == 0) {
-               ret = clk_core_prepare(core->parent);
-               if (ret)
-                       return ret;
+       int i;
 
-               trace_clk_prepare(core);
+       if (!core->parents) {
+               core->parents = kcalloc(core->num_parents,
+                                       sizeof(struct clk *), GFP_KERNEL);
+               if (!core->parents)
+                       return -ENOMEM;
+       }
 
-               if (core->ops->prepare)
-                       ret = core->ops->prepare(core->hw);
+       /*
+        * find index of new parent clock using cached parent ptrs,
+        * or if not yet cached, use string name comparison and cache
+        * them now to avoid future calls to clk_core_lookup.
+        */
+       for (i = 0; i < core->num_parents; i++) {
+               if (core->parents[i] == parent)
+                       return i;
 
-               trace_clk_prepare_complete(core);
+               if (core->parents[i])
+                       continue;
 
-               if (ret) {
-                       clk_core_unprepare(core->parent);
-                       return ret;
+               if (!strcmp(core->parent_names[i], parent->name)) {
+                       core->parents[i] = clk_core_lookup(parent->name);
+                       return i;
                }
        }
 
-       core->prepare_count++;
-
-       return 0;
+       return -EINVAL;
 }
 
-/**
- * clk_prepare - prepare a clock source
- * @clk: the clk being prepared
- *
- * clk_prepare may sleep, which differentiates it from clk_enable.  In a simple
- * case, clk_prepare can be used instead of clk_enable to ungate a clk if the
- * operation may sleep.  One example is a clk which is accessed over I2c.  In
- * the complex case a clk ungate operation may require a fast and a slow part.
- * It is this reason that clk_prepare and clk_enable are not mutually
- * exclusive.  In fact clk_prepare must be called before clk_enable.
- * Returns 0 on success, -EERROR otherwise.
- */
-int clk_prepare(struct clk *clk)
+static void clk_reparent(struct clk_core *core, struct clk_core *new_parent)
 {
-       int ret;
-
-       if (!clk)
-               return 0;
+       hlist_del(&core->child_node);
 
-       clk_prepare_lock();
-       ret = clk_core_prepare(clk->core);
-       clk_prepare_unlock();
-
-       return ret;
-}
-EXPORT_SYMBOL_GPL(clk_prepare);
-
-static void clk_core_disable(struct clk_core *core)
-{
-       if (!core)
-               return;
-
-       if (WARN_ON(core->enable_count == 0))
-               return;
-
-       if (--core->enable_count > 0)
-               return;
-
-       trace_clk_disable(core);
-
-       if (core->ops->disable)
-               core->ops->disable(core->hw);
+       if (new_parent) {
+               /* avoid duplicate POST_RATE_CHANGE notifications */
+               if (new_parent->new_child == core)
+                       new_parent->new_child = NULL;
 
-       trace_clk_disable_complete(core);
+               hlist_add_head(&core->child_node, &new_parent->children);
+       } else {
+               hlist_add_head(&core->child_node, &clk_orphan_list);
+       }
 
-       clk_core_disable(core->parent);
+       core->parent = new_parent;
 }
 
-/**
- * clk_disable - gate a clock
- * @clk: the clk being gated
- *
- * clk_disable must not sleep, which differentiates it from clk_unprepare.  In
- * a simple case, clk_disable can be used instead of clk_unprepare to gate a
- * clk if the operation is fast and will never sleep.  One example is a
- * SoC-internal clk which is controlled via simple register writes.  In the
- * complex case a clk gate operation may require a fast and a slow part.  It is
- * this reason that clk_unprepare and clk_disable are not mutually exclusive.
- * In fact clk_disable must be called before clk_unprepare.
- */
-void clk_disable(struct clk *clk)
+static struct clk_core *__clk_set_parent_before(struct clk_core *core,
+                                          struct clk_core *parent)
 {
        unsigned long flags;
+       struct clk_core *old_parent = core->parent;
 
-       if (IS_ERR_OR_NULL(clk))
-               return;
+       /*
+        * Migrate prepare state between parents and prevent race with
+        * clk_enable().
+        *
+        * If the clock is not prepared, then a race with
+        * clk_enable/disable() is impossible since we already have the
+        * prepare lock (future calls to clk_enable() need to be preceded by
+        * a clk_prepare()).
+        *
+        * If the clock is prepared, migrate the prepared state to the new
+        * parent and also protect against a race with clk_enable() by
+        * forcing the clock and the new parent on.  This ensures that all
+        * future calls to clk_enable() are practically NOPs with respect to
+        * hardware and software states.
+        *
+        * See also: Comment for clk_set_parent() below.
+        */
+       if (core->prepare_count) {
+               clk_core_prepare(parent);
+               clk_core_enable(parent);
+               clk_core_enable(core);
+       }
 
+       /* update the clk tree topology */
        flags = clk_enable_lock();
-       clk_core_disable(clk->core);
+       clk_reparent(core, parent);
        clk_enable_unlock(flags);
+
+       return old_parent;
 }
-EXPORT_SYMBOL_GPL(clk_disable);
 
-static int clk_core_enable(struct clk_core *core)
+static void __clk_set_parent_after(struct clk_core *core,
+                                  struct clk_core *parent,
+                                  struct clk_core *old_parent)
 {
-       int ret = 0;
-
-       if (!core)
-               return 0;
+       /*
+        * Finish the migration of prepare state and undo the changes done
+        * for preventing a race with clk_enable().
+        */
+       if (core->prepare_count) {
+               clk_core_disable(core);
+               clk_core_disable(old_parent);
+               clk_core_unprepare(old_parent);
+       }
+}
 
-       if (WARN_ON(core->prepare_count == 0))
-               return -ESHUTDOWN;
+static int __clk_set_parent(struct clk_core *core, struct clk_core *parent,
+                           u8 p_index)
+{
+       unsigned long flags;
+       int ret = 0;
+       struct clk_core *old_parent;
 
-       if (core->enable_count == 0) {
-               ret = clk_core_enable(core->parent);
+       old_parent = __clk_set_parent_before(core, parent);
 
-               if (ret)
-                       return ret;
+       trace_clk_set_parent(core, parent);
 
-               trace_clk_enable(core);
+       /* change clock input source */
+       if (parent && core->ops->set_parent)
+               ret = core->ops->set_parent(core->hw, p_index);
 
-               if (core->ops->enable)
-                       ret = core->ops->enable(core->hw);
+       trace_clk_set_parent_complete(core, parent);
 
-               trace_clk_enable_complete(core);
+       if (ret) {
+               flags = clk_enable_lock();
+               clk_reparent(core, old_parent);
+               clk_enable_unlock(flags);
 
-               if (ret) {
-                       clk_core_disable(core->parent);
-                       return ret;
+               if (core->prepare_count) {
+                       clk_core_disable(core);
+                       clk_core_disable(parent);
+                       clk_core_unprepare(parent);
                }
+               return ret;
        }
 
-       core->enable_count++;
+       __clk_set_parent_after(core, parent, old_parent);
+
        return 0;
 }
 
 /**
- * clk_enable - ungate a clock
- * @clk: the clk being ungated
+ * __clk_speculate_rates
+ * @core: first clk in the subtree
+ * @parent_rate: the "future" rate of clk's parent
  *
- * clk_enable must not sleep, which differentiates it from clk_prepare.  In a
- * simple case, clk_enable can be used instead of clk_prepare to ungate a clk
- * if the operation will never sleep.  One example is a SoC-internal clk which
- * is controlled via simple register writes.  In the complex case a clk ungate
- * operation may require a fast and a slow part.  It is this reason that
- * clk_enable and clk_prepare are not mutually exclusive.  In fact clk_prepare
- * must be called before clk_enable.  Returns 0 on success, -EERROR
- * otherwise.
+ * Walks the subtree of clks starting with clk, speculating rates as it
+ * goes and firing off PRE_RATE_CHANGE notifications as necessary.
+ *
+ * Unlike clk_recalc_rates, clk_speculate_rates exists only for sending
+ * pre-rate change notifications and returns early if no clks in the
+ * subtree have subscribed to the notifications.  Note that if a clk does not
+ * implement the .recalc_rate callback then it is assumed that the clock will
+ * take on the rate of its parent.
+ *
+ * Caller must hold prepare_lock.
  */
-int clk_enable(struct clk *clk)
+static int __clk_speculate_rates(struct clk_core *core,
+                                unsigned long parent_rate)
 {
-       unsigned long flags;
-       int ret;
+       struct clk_core *child;
+       unsigned long new_rate;
+       int ret = NOTIFY_DONE;
 
-       if (!clk)
-               return 0;
+       lockdep_assert_held(&prepare_lock);
 
-       flags = clk_enable_lock();
-       ret = clk_core_enable(clk->core);
-       clk_enable_unlock(flags);
+       new_rate = clk_recalc(core, parent_rate);
+
+       /* abort rate change if a driver returns NOTIFY_BAD or NOTIFY_STOP */
+       if (core->notifier_count)
+               ret = __clk_notify(core, PRE_RATE_CHANGE, core->rate, new_rate);
+
+       if (ret & NOTIFY_STOP_MASK) {
+               pr_debug("%s: clk notifier callback for clock %s aborted with error %d\n",
+                               __func__, core->name, ret);
+               goto out;
+       }
+
+       hlist_for_each_entry(child, &core->children, child_node) {
+               ret = __clk_speculate_rates(child, new_rate);
+               if (ret & NOTIFY_STOP_MASK)
+                       break;
+       }
 
+out:
        return ret;
 }
-EXPORT_SYMBOL_GPL(clk_enable);
 
-static unsigned long clk_core_round_rate_nolock(struct clk_core *core,
-                                               unsigned long rate,
-                                               unsigned long min_rate,
-                                               unsigned long max_rate)
+static void clk_calc_subtree(struct clk_core *core, unsigned long new_rate,
+                            struct clk_core *new_parent, u8 p_index)
 {
-       unsigned long parent_rate = 0;
-       struct clk_core *parent;
-       struct clk_hw *parent_hw;
+       struct clk_core *child;
 
-       lockdep_assert_held(&prepare_lock);
+       core->new_rate = new_rate;
+       core->new_parent = new_parent;
+       core->new_parent_index = p_index;
+       /* include clk in new parent's PRE_RATE_CHANGE notifications */
+       core->new_child = NULL;
+       if (new_parent && new_parent != core->parent)
+               new_parent->new_child = core;
 
-       if (!core)
-               return 0;
+       hlist_for_each_entry(child, &core->children, child_node) {
+               child->new_rate = clk_recalc(child, new_rate);
+               clk_calc_subtree(child, child->new_rate, NULL, 0);
+       }
+}
 
-       parent = core->parent;
+/*
+ * calculate the new rates returning the topmost clock that has to be
+ * changed.
+ */
+static struct clk_core *clk_calc_new_rates(struct clk_core *core,
+                                          unsigned long rate)
+{
+       struct clk_core *top = core;
+       struct clk_core *old_parent, *parent;
+       struct clk_hw *parent_hw;
+       unsigned long best_parent_rate = 0;
+       unsigned long new_rate;
+       unsigned long min_rate;
+       unsigned long max_rate;
+       int p_index = 0;
+       long ret;
+
+       /* sanity */
+       if (IS_ERR_OR_NULL(core))
+               return NULL;
+
+       /* save parent rate, if it exists */
+       parent = old_parent = core->parent;
        if (parent)
-               parent_rate = parent->rate;
+               best_parent_rate = parent->rate;
 
+       clk_core_get_boundaries(core, &min_rate, &max_rate);
+
+       /* find the closest rate and parent clk/rate */
        if (core->ops->determine_rate) {
                parent_hw = parent ? parent->hw : NULL;
-               return core->ops->determine_rate(core->hw, rate,
-                                               min_rate, max_rate,
-                                               &parent_rate, &parent_hw);
-       } else if (core->ops->round_rate)
-               return core->ops->round_rate(core->hw, rate, &parent_rate);
-       else if (core->flags & CLK_SET_RATE_PARENT)
-               return clk_core_round_rate_nolock(core->parent, rate, min_rate,
-                                                 max_rate);
-       else
-               return core->rate;
-}
-
-/**
- * __clk_determine_rate - get the closest rate actually supported by a clock
- * @hw: determine the rate of this clock
- * @rate: target rate
- * @min_rate: returned rate must be greater than this rate
- * @max_rate: returned rate must be less than this rate
- *
- * Caller must hold prepare_lock.  Useful for clk_ops such as .set_rate and
- * .determine_rate.
- */
-unsigned long __clk_determine_rate(struct clk_hw *hw,
-                                  unsigned long rate,
-                                  unsigned long min_rate,
-                                  unsigned long max_rate)
-{
-       if (!hw)
-               return 0;
-
-       return clk_core_round_rate_nolock(hw->core, rate, min_rate, max_rate);
-}
-EXPORT_SYMBOL_GPL(__clk_determine_rate);
-
-/**
- * __clk_round_rate - round the given rate for a clk
- * @clk: round the rate of this clock
- * @rate: the rate which is to be rounded
- *
- * Caller must hold prepare_lock.  Useful for clk_ops such as .set_rate
- */
-unsigned long __clk_round_rate(struct clk *clk, unsigned long rate)
-{
-       unsigned long min_rate;
-       unsigned long max_rate;
+               ret = core->ops->determine_rate(core->hw, rate,
+                                              min_rate,
+                                              max_rate,
+                                              &best_parent_rate,
+                                              &parent_hw);
+               if (ret < 0)
+                       return NULL;
 
-       if (!clk)
-               return 0;
+               new_rate = ret;
+               parent = parent_hw ? parent_hw->core : NULL;
+       } else if (core->ops->round_rate) {
+               ret = core->ops->round_rate(core->hw, rate,
+                                          &best_parent_rate);
+               if (ret < 0)
+                       return NULL;
 
-       clk_core_get_boundaries(clk->core, &min_rate, &max_rate);
+               new_rate = ret;
+               if (new_rate < min_rate || new_rate > max_rate)
+                       return NULL;
+       } else if (!parent || !(core->flags & CLK_SET_RATE_PARENT)) {
+               /* pass-through clock without adjustable parent */
+               core->new_rate = core->rate;
+               return NULL;
+       } else {
+               /* pass-through clock with adjustable parent */
+               top = clk_calc_new_rates(parent, rate);
+               new_rate = parent->new_rate;
+               goto out;
+       }
 
-       return clk_core_round_rate_nolock(clk->core, rate, min_rate, max_rate);
-}
-EXPORT_SYMBOL_GPL(__clk_round_rate);
+       /* some clocks must be gated to change parent */
+       if (parent != old_parent &&
+           (core->flags & CLK_SET_PARENT_GATE) && core->prepare_count) {
+               pr_debug("%s: %s not gated but wants to reparent\n",
+                        __func__, core->name);
+               return NULL;
+       }
 
-/**
- * clk_round_rate - round the given rate for a clk
- * @clk: the clk for which we are rounding a rate
- * @rate: the rate which is to be rounded
- *
- * Takes in a rate as input and rounds it to a rate that the clk can actually
- * use which is then returned.  If clk doesn't support round_rate operation
- * then the parent rate is returned.
- */
-long clk_round_rate(struct clk *clk, unsigned long rate)
-{
-       unsigned long ret;
+       /* try finding the new parent index */
+       if (parent && core->num_parents > 1) {
+               p_index = clk_fetch_parent_index(core, parent);
+               if (p_index < 0) {
+                       pr_debug("%s: clk %s can not be parent of clk %s\n",
+                                __func__, parent->name, core->name);
+                       return NULL;
+               }
+       }
 
-       if (!clk)
-               return 0;
+       if ((core->flags & CLK_SET_RATE_PARENT) && parent &&
+           best_parent_rate != parent->rate)
+               top = clk_calc_new_rates(parent, best_parent_rate);
 
-       clk_prepare_lock();
-       ret = __clk_round_rate(clk, rate);
-       clk_prepare_unlock();
+out:
+       clk_calc_subtree(core, new_rate, parent, p_index);
 
-       return ret;
+       return top;
 }
-EXPORT_SYMBOL_GPL(clk_round_rate);
 
-/**
- * __clk_notify - call clk notifier chain
- * @core: clk that is changing rate
- * @msg: clk notifier type (see include/linux/clk.h)
- * @old_rate: old clk rate
- * @new_rate: new clk rate
- *
- * Triggers a notifier call chain on the clk rate-change notification
- * for 'clk'.  Passes a pointer to the struct clk and the previous
- * and current rates to the notifier callback.  Intended to be called by
- * internal clock code only.  Returns NOTIFY_DONE from the last driver
- * called if all went well, or NOTIFY_STOP or NOTIFY_BAD immediately if
- * a driver returns that.
+/*
+ * Notify about rate changes in a subtree. Always walk down the whole tree
+ * so that in case of an error we can walk down the whole tree again and
+ * abort the change.
  */
-static int __clk_notify(struct clk_core *core, unsigned long msg,
-               unsigned long old_rate, unsigned long new_rate)
+static struct clk_core *clk_propagate_rate_change(struct clk_core *core,
+                                                 unsigned long event)
 {
-       struct clk_notifier *cn;
-       struct clk_notifier_data cnd;
+       struct clk_core *child, *tmp_clk, *fail_clk = NULL;
        int ret = NOTIFY_DONE;
 
-       cnd.old_rate = old_rate;
-       cnd.new_rate = new_rate;
+       if (core->rate == core->new_rate)
+               return NULL;
 
-       list_for_each_entry(cn, &clk_notifier_list, node) {
-               if (cn->clk->core == core) {
-                       cnd.clk = cn->clk;
-                       ret = srcu_notifier_call_chain(&cn->notifier_head, msg,
-                                       &cnd);
-               }
+       if (core->notifier_count) {
+               ret = __clk_notify(core, event, core->rate, core->new_rate);
+               if (ret & NOTIFY_STOP_MASK)
+                       fail_clk = core;
        }
 
-       return ret;
-}
-
-/**
- * __clk_recalc_accuracies
- * @core: first clk in the subtree
- *
- * Walks the subtree of clks starting with clk and recalculates accuracies as
- * it goes.  Note that if a clk does not implement the .recalc_accuracy
- * callback then it is assumed that the clock will take on the accuracy of it's
- * parent.
- *
- * Caller must hold prepare_lock.
- */
-static void __clk_recalc_accuracies(struct clk_core *core)
-{
-       unsigned long parent_accuracy = 0;
-       struct clk_core *child;
-
-       lockdep_assert_held(&prepare_lock);
-
-       if (core->parent)
-               parent_accuracy = core->parent->accuracy;
+       hlist_for_each_entry(child, &core->children, child_node) {
+               /* Skip children who will be reparented to another clock */
+               if (child->new_parent && child->new_parent != core)
+                       continue;
+               tmp_clk = clk_propagate_rate_change(child, event);
+               if (tmp_clk)
+                       fail_clk = tmp_clk;
+       }
 
-       if (core->ops->recalc_accuracy)
-               core->accuracy = core->ops->recalc_accuracy(core->hw,
-                                                         parent_accuracy);
-       else
-               core->accuracy = parent_accuracy;
+       /* handle the new child who might not be in core->children yet */
+       if (core->new_child) {
+               tmp_clk = clk_propagate_rate_change(core->new_child, event);
+               if (tmp_clk)
+                       fail_clk = tmp_clk;
+       }
 
-       hlist_for_each_entry(child, &core->children, child_node)
-               __clk_recalc_accuracies(child);
+       return fail_clk;
 }
 
-static long clk_core_get_accuracy(struct clk_core *core)
+/*
+ * walk down a subtree and set the new rates notifying the rate
+ * change on the way
+ */
+static void clk_change_rate(struct clk_core *core)
 {
-       unsigned long accuracy;
-
-       clk_prepare_lock();
-       if (core && (core->flags & CLK_GET_ACCURACY_NOCACHE))
-               __clk_recalc_accuracies(core);
+       struct clk_core *child;
+       struct hlist_node *tmp;
+       unsigned long old_rate;
+       unsigned long best_parent_rate = 0;
+       bool skip_set_rate = false;
+       struct clk_core *old_parent;
 
-       accuracy = __clk_get_accuracy(core);
-       clk_prepare_unlock();
+       old_rate = core->rate;
 
-       return accuracy;
-}
+       if (core->new_parent)
+               best_parent_rate = core->new_parent->rate;
+       else if (core->parent)
+               best_parent_rate = core->parent->rate;
 
-/**
- * clk_get_accuracy - return the accuracy of clk
- * @clk: the clk whose accuracy is being returned
- *
- * Simply returns the cached accuracy of the clk, unless
- * CLK_GET_ACCURACY_NOCACHE flag is set, which means a recalc_rate will be
- * issued.
- * If clk is NULL then returns 0.
- */
-long clk_get_accuracy(struct clk *clk)
-{
-       if (!clk)
-               return 0;
+       if (core->new_parent && core->new_parent != core->parent) {
+               old_parent = __clk_set_parent_before(core, core->new_parent);
+               trace_clk_set_parent(core, core->new_parent);
 
-       return clk_core_get_accuracy(clk->core);
-}
-EXPORT_SYMBOL_GPL(clk_get_accuracy);
+               if (core->ops->set_rate_and_parent) {
+                       skip_set_rate = true;
+                       core->ops->set_rate_and_parent(core->hw, core->new_rate,
+                                       best_parent_rate,
+                                       core->new_parent_index);
+               } else if (core->ops->set_parent) {
+                       core->ops->set_parent(core->hw, core->new_parent_index);
+               }
 
-static unsigned long clk_recalc(struct clk_core *core,
-                               unsigned long parent_rate)
-{
-       if (core->ops->recalc_rate)
-               return core->ops->recalc_rate(core->hw, parent_rate);
-       return parent_rate;
-}
+               trace_clk_set_parent_complete(core, core->new_parent);
+               __clk_set_parent_after(core, core->new_parent, old_parent);
+       }
 
-/**
- * __clk_recalc_rates
- * @core: first clk in the subtree
- * @msg: notification type (see include/linux/clk.h)
- *
- * Walks the subtree of clks starting with clk and recalculates rates as it
- * goes.  Note that if a clk does not implement the .recalc_rate callback then
- * it is assumed that the clock will take on the rate of its parent.
- *
- * clk_recalc_rates also propagates the POST_RATE_CHANGE notification,
- * if necessary.
- *
- * Caller must hold prepare_lock.
- */
-static void __clk_recalc_rates(struct clk_core *core, unsigned long msg)
-{
-       unsigned long old_rate;
-       unsigned long parent_rate = 0;
-       struct clk_core *child;
+       trace_clk_set_rate(core, core->new_rate);
 
-       lockdep_assert_held(&prepare_lock);
+       if (!skip_set_rate && core->ops->set_rate)
+               core->ops->set_rate(core->hw, core->new_rate, best_parent_rate);
 
-       old_rate = core->rate;
+       trace_clk_set_rate_complete(core, core->new_rate);
 
-       if (core->parent)
-               parent_rate = core->parent->rate;
+       core->rate = clk_recalc(core, best_parent_rate);
 
-       core->rate = clk_recalc(core, parent_rate);
+       if (core->notifier_count && old_rate != core->rate)
+               __clk_notify(core, POST_RATE_CHANGE, old_rate, core->rate);
 
        /*
-        * ignore NOTIFY_STOP and NOTIFY_BAD return values for POST_RATE_CHANGE
-        * & ABORT_RATE_CHANGE notifiers
+        * Use safe iteration, as change_rate can actually swap parents
+        * for certain clock types.
         */
-       if (core->notifier_count && msg)
-               __clk_notify(core, msg, old_rate, core->rate);
+       hlist_for_each_entry_safe(child, tmp, &core->children, child_node) {
+               /* Skip children who will be reparented to another clock */
+               if (child->new_parent && child->new_parent != core)
+                       continue;
+               clk_change_rate(child);
+       }
 
-       hlist_for_each_entry(child, &core->children, child_node)
-               __clk_recalc_rates(child, msg);
+       /* handle the new child who might not be in core->children yet */
+       if (core->new_child)
+               clk_change_rate(core->new_child);
 }
 
-static unsigned long clk_core_get_rate(struct clk_core *core)
+static int clk_core_set_rate_nolock(struct clk_core *core,
+                                   unsigned long req_rate)
 {
-       unsigned long rate;
+       struct clk_core *top, *fail_clk;
+       unsigned long rate = req_rate;
+       int ret = 0;
 
-       clk_prepare_lock();
+       if (!core)
+               return 0;
 
-       if (core && (core->flags & CLK_GET_RATE_NOCACHE))
-               __clk_recalc_rates(core, 0);
+       /* bail early if nothing to do */
+       if (rate == clk_core_get_rate_nolock(core))
+               return 0;
 
-       rate = clk_core_get_rate_nolock(core);
-       clk_prepare_unlock();
+       if ((core->flags & CLK_SET_RATE_GATE) && core->prepare_count)
+               return -EBUSY;
 
-       return rate;
+       /* calculate new rates and get the topmost changed clock */
+       top = clk_calc_new_rates(core, rate);
+       if (!top)
+               return -EINVAL;
+
+       /* notify that we are about to change rates */
+       fail_clk = clk_propagate_rate_change(top, PRE_RATE_CHANGE);
+       if (fail_clk) {
+               pr_debug("%s: failed to set %s rate\n", __func__,
+                               fail_clk->name);
+               clk_propagate_rate_change(top, ABORT_RATE_CHANGE);
+               return -EBUSY;
+       }
+
+       /* change the rates */
+       clk_change_rate(top);
+
+       core->req_rate = req_rate;
+
+       return ret;
 }
 
 /**
- * clk_get_rate - return the rate of clk
- * @clk: the clk whose rate is being returned
+ * clk_set_rate - specify a new rate for clk
+ * @clk: the clk whose rate is being changed
+ * @rate: the new rate for clk
  *
- * Simply returns the cached rate of the clk, unless CLK_GET_RATE_NOCACHE flag
- * is set, which means a recalc_rate will be issued.
- * If clk is NULL then returns 0.
+ * In the simplest case clk_set_rate will only adjust the rate of clk.
+ *
+ * Setting the CLK_SET_RATE_PARENT flag allows the rate change operation to
+ * propagate up to clk's parent; whether or not this happens depends on the
+ * outcome of clk's .round_rate implementation.  If *parent_rate is unchanged
+ * after calling .round_rate then upstream parent propagation is ignored.  If
+ * *parent_rate comes back with a new rate for clk's parent then we propagate
+ * up to clk's parent and set its rate.  Upward propagation will continue
+ * until either a clk does not support the CLK_SET_RATE_PARENT flag or
+ * .round_rate stops requesting changes to clk's parent_rate.
+ *
+ * Rate changes are accomplished via tree traversal that also recalculates the
+ * rates for the clocks and fires off POST_RATE_CHANGE notifiers.
+ *
+ * Returns 0 on success, -EERROR otherwise.
  */
-unsigned long clk_get_rate(struct clk *clk)
+int clk_set_rate(struct clk *clk, unsigned long rate)
 {
+       int ret;
+
        if (!clk)
                return 0;
 
-       return clk_core_get_rate(clk->core);
-}
-EXPORT_SYMBOL_GPL(clk_get_rate);
-
-static int clk_fetch_parent_index(struct clk_core *core,
-                                 struct clk_core *parent)
-{
-       int i;
-
-       if (!core->parents) {
-               core->parents = kcalloc(core->num_parents,
-                                       sizeof(struct clk *), GFP_KERNEL);
-               if (!core->parents)
-                       return -ENOMEM;
-       }
-
-       /*
-        * find index of new parent clock using cached parent ptrs,
-        * or if not yet cached, use string name comparison and cache
-        * them now to avoid future calls to clk_core_lookup.
-        */
-       for (i = 0; i < core->num_parents; i++) {
-               if (core->parents[i] == parent)
-                       return i;
+       /* prevent racing with updates to the clock topology */
+       clk_prepare_lock();
 
-               if (core->parents[i])
-                       continue;
+       ret = clk_core_set_rate_nolock(clk->core, rate);
 
-               if (!strcmp(core->parent_names[i], parent->name)) {
-                       core->parents[i] = clk_core_lookup(parent->name);
-                       return i;
-               }
-       }
+       clk_prepare_unlock();
 
-       return -EINVAL;
+       return ret;
 }
+EXPORT_SYMBOL_GPL(clk_set_rate);
 
-static void clk_reparent(struct clk_core *core, struct clk_core *new_parent)
+/**
+ * clk_set_rate_range - set a rate range for a clock source
+ * @clk: clock source
+ * @min: desired minimum clock rate in Hz, inclusive
+ * @max: desired maximum clock rate in Hz, inclusive
+ *
+ * Returns success (0) or negative errno.
+ */
+int clk_set_rate_range(struct clk *clk, unsigned long min, unsigned long max)
 {
-       hlist_del(&core->child_node);
+       int ret = 0;
 
-       if (new_parent) {
-               /* avoid duplicate POST_RATE_CHANGE notifications */
-               if (new_parent->new_child == core)
-                       new_parent->new_child = NULL;
+       if (!clk)
+               return 0;
 
-               hlist_add_head(&core->child_node, &new_parent->children);
-       } else {
-               hlist_add_head(&core->child_node, &clk_orphan_list);
+       if (min > max) {
+               pr_err("%s: clk %s dev %s con %s: invalid range [%lu, %lu]\n",
+                      __func__, clk->core->name, clk->dev_id, clk->con_id,
+                      min, max);
+               return -EINVAL;
        }
 
-       core->parent = new_parent;
-}
-
-static struct clk_core *__clk_set_parent_before(struct clk_core *core,
-                                          struct clk_core *parent)
-{
-       unsigned long flags;
-       struct clk_core *old_parent = core->parent;
+       clk_prepare_lock();
 
-       /*
-        * Migrate prepare state between parents and prevent race with
-        * clk_enable().
-        *
-        * If the clock is not prepared, then a race with
-        * clk_enable/disable() is impossible since we already have the
-        * prepare lock (future calls to clk_enable() need to be preceded by
-        * a clk_prepare()).
-        *
-        * If the clock is prepared, migrate the prepared state to the new
-        * parent and also protect against a race with clk_enable() by
-        * forcing the clock and the new parent on.  This ensures that all
-        * future calls to clk_enable() are practically NOPs with respect to
-        * hardware and software states.
-        *
-        * See also: Comment for clk_set_parent() below.
-        */
-       if (core->prepare_count) {
-               clk_core_prepare(parent);
-               clk_core_enable(parent);
-               clk_core_enable(core);
+       if (min != clk->min_rate || max != clk->max_rate) {
+               clk->min_rate = min;
+               clk->max_rate = max;
+               ret = clk_core_set_rate_nolock(clk->core, clk->core->req_rate);
        }
 
-       /* update the clk tree topology */
-       flags = clk_enable_lock();
-       clk_reparent(core, parent);
-       clk_enable_unlock(flags);
+       clk_prepare_unlock();
 
-       return old_parent;
+       return ret;
 }
+EXPORT_SYMBOL_GPL(clk_set_rate_range);
 
-static void __clk_set_parent_after(struct clk_core *core,
-                                  struct clk_core *parent,
-                                  struct clk_core *old_parent)
+/**
+ * clk_set_min_rate - set a minimum clock rate for a clock source
+ * @clk: clock source
+ * @rate: desired minimum clock rate in Hz, inclusive
+ *
+ * Returns success (0) or negative errno.
+ */
+int clk_set_min_rate(struct clk *clk, unsigned long rate)
 {
-       /*
-        * Finish the migration of prepare state and undo the changes done
-        * for preventing a race with clk_enable().
-        */
-       if (core->prepare_count) {
-               clk_core_disable(core);
-               clk_core_disable(old_parent);
-               clk_core_unprepare(old_parent);
-       }
+       if (!clk)
+               return 0;
+
+       return clk_set_rate_range(clk, rate, clk->max_rate);
 }
+EXPORT_SYMBOL_GPL(clk_set_min_rate);
 
-static int __clk_set_parent(struct clk_core *core, struct clk_core *parent,
-                           u8 p_index)
+/**
+ * clk_set_max_rate - set a maximum clock rate for a clock source
+ * @clk: clock source
+ * @rate: desired maximum clock rate in Hz, inclusive
+ *
+ * Returns success (0) or negative errno.
+ */
+int clk_set_max_rate(struct clk *clk, unsigned long rate)
 {
-       unsigned long flags;
-       int ret = 0;
-       struct clk_core *old_parent;
-
-       old_parent = __clk_set_parent_before(core, parent);
-
-       trace_clk_set_parent(core, parent);
-
-       /* change clock input source */
-       if (parent && core->ops->set_parent)
-               ret = core->ops->set_parent(core->hw, p_index);
-
-       trace_clk_set_parent_complete(core, parent);
-
-       if (ret) {
-               flags = clk_enable_lock();
-               clk_reparent(core, old_parent);
-               clk_enable_unlock(flags);
-
-               if (core->prepare_count) {
-                       clk_core_disable(core);
-                       clk_core_disable(parent);
-                       clk_core_unprepare(parent);
-               }
-               return ret;
-       }
-
-       __clk_set_parent_after(core, parent, old_parent);
+       if (!clk)
+               return 0;
 
-       return 0;
+       return clk_set_rate_range(clk, clk->min_rate, rate);
 }
+EXPORT_SYMBOL_GPL(clk_set_max_rate);
 
 /**
- * __clk_speculate_rates
- * @core: first clk in the subtree
- * @parent_rate: the "future" rate of clk's parent
- *
- * Walks the subtree of clks starting with clk, speculating rates as it
- * goes and firing off PRE_RATE_CHANGE notifications as necessary.
- *
- * Unlike clk_recalc_rates, clk_speculate_rates exists only for sending
- * pre-rate change notifications and returns early if no clks in the
- * subtree have subscribed to the notifications.  Note that if a clk does not
- * implement the .recalc_rate callback then it is assumed that the clock will
- * take on the rate of its parent.
+ * clk_get_parent - return the parent of a clk
+ * @clk: the clk whose parent gets returned
  *
- * Caller must hold prepare_lock.
+ * Simply returns clk->parent.  Returns NULL if clk is NULL.
  */
-static int __clk_speculate_rates(struct clk_core *core,
-                                unsigned long parent_rate)
+struct clk *clk_get_parent(struct clk *clk)
 {
-       struct clk_core *child;
-       unsigned long new_rate;
-       int ret = NOTIFY_DONE;
+       struct clk *parent;
 
-       lockdep_assert_held(&prepare_lock);
+       clk_prepare_lock();
+       parent = __clk_get_parent(clk);
+       clk_prepare_unlock();
 
-       new_rate = clk_recalc(core, parent_rate);
+       return parent;
+}
+EXPORT_SYMBOL_GPL(clk_get_parent);
 
-       /* abort rate change if a driver returns NOTIFY_BAD or NOTIFY_STOP */
-       if (core->notifier_count)
-               ret = __clk_notify(core, PRE_RATE_CHANGE, core->rate, new_rate);
+/*
+ * .get_parent is mandatory for clocks with multiple possible parents.  It is
+ * optional for single-parent clocks.  Always call .get_parent if it is
+ * available and WARN if it is missing for multi-parent clocks.
+ *
+ * For single-parent clocks without .get_parent, first check to see if the
+ * .parents array exists, and if so use it to avoid an expensive tree
+ * traversal.  If .parents does not exist then walk the tree.
+ */
+static struct clk_core *__clk_init_parent(struct clk_core *core)
+{
+       struct clk_core *ret = NULL;
+       u8 index;
 
-       if (ret & NOTIFY_STOP_MASK) {
-               pr_debug("%s: clk notifier callback for clock %s aborted with error %d\n",
-                               __func__, core->name, ret);
+       /* handle the trivial cases */
+
+       if (!core->num_parents)
                goto out;
-       }
 
-       hlist_for_each_entry(child, &core->children, child_node) {
-               ret = __clk_speculate_rates(child, new_rate);
-               if (ret & NOTIFY_STOP_MASK)
-                       break;
+       if (core->num_parents == 1) {
+               if (IS_ERR_OR_NULL(core->parent))
+                       core->parent = clk_core_lookup(core->parent_names[0]);
+               ret = core->parent;
+               goto out;
        }
 
+       if (!core->ops->get_parent) {
+               WARN(!core->ops->get_parent,
+                       "%s: multi-parent clocks must implement .get_parent\n",
+                       __func__);
+               goto out;
+       };
+
+       /*
+        * Do our best to cache parent clocks in core->parents.  This prevents
+        * unnecessary and expensive lookups.  We don't set core->parent here;
+        * that is done by the calling function.
+        */
+
+       index = core->ops->get_parent(core->hw);
+
+       if (!core->parents)
+               core->parents =
+                       kcalloc(core->num_parents, sizeof(struct clk *),
+                                       GFP_KERNEL);
+
+       ret = clk_core_get_parent_by_index(core, index);
+
 out:
        return ret;
 }
 
-static void clk_calc_subtree(struct clk_core *core, unsigned long new_rate,
-                            struct clk_core *new_parent, u8 p_index)
+static void clk_core_reparent(struct clk_core *core,
+                                 struct clk_core *new_parent)
 {
-       struct clk_core *child;
-
-       core->new_rate = new_rate;
-       core->new_parent = new_parent;
-       core->new_parent_index = p_index;
-       /* include clk in new parent's PRE_RATE_CHANGE notifications */
-       core->new_child = NULL;
-       if (new_parent && new_parent != core->parent)
-               new_parent->new_child = core;
-
-       hlist_for_each_entry(child, &core->children, child_node) {
-               child->new_rate = clk_recalc(child, new_rate);
-               clk_calc_subtree(child, child->new_rate, NULL, 0);
-       }
+       clk_reparent(core, new_parent);
+       __clk_recalc_accuracies(core);
+       __clk_recalc_rates(core, POST_RATE_CHANGE);
 }
 
-/*
- * calculate the new rates returning the topmost clock that has to be
- * changed.
+/**
+ * clk_has_parent - check if a clock is a possible parent for another
+ * @clk: clock source
+ * @parent: parent clock source
+ *
+ * This function can be used in drivers that need to check that a clock can be
+ * the parent of another without actually changing the parent.
+ *
+ * Returns true if @parent is a possible parent for @clk, false otherwise.
  */
-static struct clk_core *clk_calc_new_rates(struct clk_core *core,
-                                          unsigned long rate)
+bool clk_has_parent(struct clk *clk, struct clk *parent)
 {
-       struct clk_core *top = core;
-       struct clk_core *old_parent, *parent;
-       struct clk_hw *parent_hw;
-       unsigned long best_parent_rate = 0;
-       unsigned long new_rate;
-       unsigned long min_rate;
-       unsigned long max_rate;
-       int p_index = 0;
-       long ret;
+       struct clk_core *core, *parent_core;
+       unsigned int i;
 
-       /* sanity */
-       if (IS_ERR_OR_NULL(core))
-               return NULL;
+       /* NULL clocks should be nops, so return success if either is NULL. */
+       if (!clk || !parent)
+               return true;
 
-       /* save parent rate, if it exists */
-       parent = old_parent = core->parent;
-       if (parent)
-               best_parent_rate = parent->rate;
+       core = clk->core;
+       parent_core = parent->core;
 
-       clk_core_get_boundaries(core, &min_rate, &max_rate);
+       /* Optimize for the case where the parent is already the parent. */
+       if (core->parent == parent_core)
+               return true;
 
-       /* find the closest rate and parent clk/rate */
-       if (core->ops->determine_rate) {
-               parent_hw = parent ? parent->hw : NULL;
-               ret = core->ops->determine_rate(core->hw, rate,
-                                              min_rate,
-                                              max_rate,
-                                              &best_parent_rate,
-                                              &parent_hw);
-               if (ret < 0)
-                       return NULL;
+       for (i = 0; i < core->num_parents; i++)
+               if (strcmp(core->parent_names[i], parent_core->name) == 0)
+                       return true;
 
-               new_rate = ret;
-               parent = parent_hw ? parent_hw->core : NULL;
-       } else if (core->ops->round_rate) {
-               ret = core->ops->round_rate(core->hw, rate,
-                                          &best_parent_rate);
-               if (ret < 0)
-                       return NULL;
+       return false;
+}
+EXPORT_SYMBOL_GPL(clk_has_parent);
 
-               new_rate = ret;
-               if (new_rate < min_rate || new_rate > max_rate)
-                       return NULL;
-       } else if (!parent || !(core->flags & CLK_SET_RATE_PARENT)) {
-               /* pass-through clock without adjustable parent */
-               core->new_rate = core->rate;
-               return NULL;
-       } else {
-               /* pass-through clock with adjustable parent */
-               top = clk_calc_new_rates(parent, rate);
-               new_rate = parent->new_rate;
+static int clk_core_set_parent(struct clk_core *core, struct clk_core *parent)
+{
+       int ret = 0;
+       int p_index = 0;
+       unsigned long p_rate = 0;
+
+       if (!core)
+               return 0;
+
+       /* prevent racing with updates to the clock topology */
+       clk_prepare_lock();
+
+       if (core->parent == parent)
+               goto out;
+
+       /* verify ops for for multi-parent clks */
+       if ((core->num_parents > 1) && (!core->ops->set_parent)) {
+               ret = -ENOSYS;
                goto out;
        }
 
-       /* some clocks must be gated to change parent */
-       if (parent != old_parent &&
-           (core->flags & CLK_SET_PARENT_GATE) && core->prepare_count) {
-               pr_debug("%s: %s not gated but wants to reparent\n",
-                        __func__, core->name);
-               return NULL;
+       /* check that we are allowed to re-parent if the clock is in use */
+       if ((core->flags & CLK_SET_PARENT_GATE) && core->prepare_count) {
+               ret = -EBUSY;
+               goto out;
        }
 
        /* try finding the new parent index */
-       if (parent && core->num_parents > 1) {
+       if (parent) {
                p_index = clk_fetch_parent_index(core, parent);
+               p_rate = parent->rate;
                if (p_index < 0) {
                        pr_debug("%s: clk %s can not be parent of clk %s\n",
-                                __func__, parent->name, core->name);
-                       return NULL;
+                                       __func__, parent->name, core->name);
+                       ret = p_index;
+                       goto out;
                }
        }
 
-       if ((core->flags & CLK_SET_RATE_PARENT) && parent &&
-           best_parent_rate != parent->rate)
-               top = clk_calc_new_rates(parent, best_parent_rate);
-
-out:
-       clk_calc_subtree(core, new_rate, parent, p_index);
-
-       return top;
-}
+       /* propagate PRE_RATE_CHANGE notifications */
+       ret = __clk_speculate_rates(core, p_rate);
 
-/*
- * Notify about rate changes in a subtree. Always walk down the whole tree
- * so that in case of an error we can walk down the whole tree again and
- * abort the change.
- */
-static struct clk_core *clk_propagate_rate_change(struct clk_core *core,
-                                                 unsigned long event)
-{
-       struct clk_core *child, *tmp_clk, *fail_clk = NULL;
-       int ret = NOTIFY_DONE;
+       /* abort if a driver objects */
+       if (ret & NOTIFY_STOP_MASK)
+               goto out;
 
-       if (core->rate == core->new_rate)
-               return NULL;
+       /* do the re-parent */
+       ret = __clk_set_parent(core, parent, p_index);
 
-       if (core->notifier_count) {
-               ret = __clk_notify(core, event, core->rate, core->new_rate);
-               if (ret & NOTIFY_STOP_MASK)
-                       fail_clk = core;
+       /* propagate rate an accuracy recalculation accordingly */
+       if (ret) {
+               __clk_recalc_rates(core, ABORT_RATE_CHANGE);
+       } else {
+               __clk_recalc_rates(core, POST_RATE_CHANGE);
+               __clk_recalc_accuracies(core);
        }
 
-       hlist_for_each_entry(child, &core->children, child_node) {
-               /* Skip children who will be reparented to another clock */
-               if (child->new_parent && child->new_parent != core)
-                       continue;
-               tmp_clk = clk_propagate_rate_change(child, event);
-               if (tmp_clk)
-                       fail_clk = tmp_clk;
-       }
+out:
+       clk_prepare_unlock();
 
-       /* handle the new child who might not be in core->children yet */
-       if (core->new_child) {
-               tmp_clk = clk_propagate_rate_change(core->new_child, event);
-               if (tmp_clk)
-                       fail_clk = tmp_clk;
-       }
+       return ret;
+}
 
-       return fail_clk;
+/**
+ * clk_set_parent - switch the parent of a mux clk
+ * @clk: the mux clk whose input we are switching
+ * @parent: the new input to clk
+ *
+ * Re-parent clk to use parent as its new input source.  If clk is in
+ * prepared state, the clk will get enabled for the duration of this call. If
+ * that's not acceptable for a specific clk (Eg: the consumer can't handle
+ * that, the reparenting is glitchy in hardware, etc), use the
+ * CLK_SET_PARENT_GATE flag to allow reparenting only when clk is unprepared.
+ *
+ * After successfully changing clk's parent clk_set_parent will update the
+ * clk topology, sysfs topology and propagate rate recalculation via
+ * __clk_recalc_rates.
+ *
+ * Returns 0 on success, -EERROR otherwise.
+ */
+int clk_set_parent(struct clk *clk, struct clk *parent)
+{
+       if (!clk)
+               return 0;
+
+       return clk_core_set_parent(clk->core, parent ? parent->core : NULL);
 }
+EXPORT_SYMBOL_GPL(clk_set_parent);
 
-/*
- * walk down a subtree and set the new rates notifying the rate
- * change on the way
+/**
+ * clk_set_phase - adjust the phase shift of a clock signal
+ * @clk: clock signal source
+ * @degrees: number of degrees the signal is shifted
+ *
+ * Shifts the phase of a clock signal by the specified
+ * degrees. Returns 0 on success, -EERROR otherwise.
+ *
+ * This function makes no distinction about the input or reference
+ * signal that we adjust the clock signal phase against. For example
+ * phase locked-loop clock signal generators we may shift phase with
+ * respect to feedback clock signal input, but for other cases the
+ * clock phase may be shifted with respect to some other, unspecified
+ * signal.
+ *
+ * Additionally the concept of phase shift does not propagate through
+ * the clock tree hierarchy, which sets it apart from clock rates and
+ * clock accuracy. A parent clock phase attribute does not have an
+ * impact on the phase attribute of a child clock.
  */
-static void clk_change_rate(struct clk_core *core)
+int clk_set_phase(struct clk *clk, int degrees)
 {
-       struct clk_core *child;
-       struct hlist_node *tmp;
-       unsigned long old_rate;
-       unsigned long best_parent_rate = 0;
-       bool skip_set_rate = false;
-       struct clk_core *old_parent;
+       int ret = -EINVAL;
 
-       old_rate = core->rate;
+       if (!clk)
+               return 0;
 
-       if (core->new_parent)
-               best_parent_rate = core->new_parent->rate;
-       else if (core->parent)
-               best_parent_rate = core->parent->rate;
+       /* sanity check degrees */
+       degrees %= 360;
+       if (degrees < 0)
+               degrees += 360;
 
-       if (core->new_parent && core->new_parent != core->parent) {
-               old_parent = __clk_set_parent_before(core, core->new_parent);
-               trace_clk_set_parent(core, core->new_parent);
+       clk_prepare_lock();
 
-               if (core->ops->set_rate_and_parent) {
-                       skip_set_rate = true;
-                       core->ops->set_rate_and_parent(core->hw, core->new_rate,
-                                       best_parent_rate,
-                                       core->new_parent_index);
-               } else if (core->ops->set_parent) {
-                       core->ops->set_parent(core->hw, core->new_parent_index);
-               }
+       trace_clk_set_phase(clk->core, degrees);
 
-               trace_clk_set_parent_complete(core, core->new_parent);
-               __clk_set_parent_after(core, core->new_parent, old_parent);
-       }
+       if (clk->core->ops->set_phase)
+               ret = clk->core->ops->set_phase(clk->core->hw, degrees);
 
-       trace_clk_set_rate(core, core->new_rate);
+       trace_clk_set_phase_complete(clk->core, degrees);
 
-       if (!skip_set_rate && core->ops->set_rate)
-               core->ops->set_rate(core->hw, core->new_rate, best_parent_rate);
+       if (!ret)
+               clk->core->phase = degrees;
 
-       trace_clk_set_rate_complete(core, core->new_rate);
+       clk_prepare_unlock();
 
-       core->rate = clk_recalc(core, best_parent_rate);
+       return ret;
+}
+EXPORT_SYMBOL_GPL(clk_set_phase);
 
-       if (core->notifier_count && old_rate != core->rate)
-               __clk_notify(core, POST_RATE_CHANGE, old_rate, core->rate);
+static int clk_core_get_phase(struct clk_core *core)
+{
+       int ret;
 
-       /*
-        * Use safe iteration, as change_rate can actually swap parents
-        * for certain clock types.
-        */
-       hlist_for_each_entry_safe(child, tmp, &core->children, child_node) {
-               /* Skip children who will be reparented to another clock */
-               if (child->new_parent && child->new_parent != core)
-                       continue;
-               clk_change_rate(child);
-       }
+       clk_prepare_lock();
+       ret = core->phase;
+       clk_prepare_unlock();
 
-       /* handle the new child who might not be in core->children yet */
-       if (core->new_child)
-               clk_change_rate(core->new_child);
+       return ret;
 }
 
-static int clk_core_set_rate_nolock(struct clk_core *core,
-                                   unsigned long req_rate)
+/**
+ * clk_get_phase - return the phase shift of a clock signal
+ * @clk: clock signal source
+ *
+ * Returns the phase shift of a clock node in degrees, otherwise returns
+ * -EERROR.
+ */
+int clk_get_phase(struct clk *clk)
 {
-       struct clk_core *top, *fail_clk;
-       unsigned long rate = req_rate;
-       int ret = 0;
-
-       if (!core)
+       if (!clk)
                return 0;
 
-       /* bail early if nothing to do */
-       if (rate == clk_core_get_rate_nolock(core))
-               return 0;
+       return clk_core_get_phase(clk->core);
+}
+EXPORT_SYMBOL_GPL(clk_get_phase);
 
-       if ((core->flags & CLK_SET_RATE_GATE) && core->prepare_count)
-               return -EBUSY;
+/**
+ * clk_is_match - check if two clk's point to the same hardware clock
+ * @p: clk compared against q
+ * @q: clk compared against p
+ *
+ * Returns true if the two struct clk pointers both point to the same hardware
+ * clock node. Put differently, returns true if struct clk *p and struct clk *q
+ * share the same struct clk_core object.
+ *
+ * Returns false otherwise. Note that two NULL clks are treated as matching.
+ */
+bool clk_is_match(const struct clk *p, const struct clk *q)
+{
+       /* trivial case: identical struct clk's or both NULL */
+       if (p == q)
+               return true;
 
-       /* calculate new rates and get the topmost changed clock */
-       top = clk_calc_new_rates(core, rate);
-       if (!top)
-               return -EINVAL;
+       /* true if clk->core pointers match. Avoid derefing garbage */
+       if (!IS_ERR_OR_NULL(p) && !IS_ERR_OR_NULL(q))
+               if (p->core == q->core)
+                       return true;
 
-       /* notify that we are about to change rates */
-       fail_clk = clk_propagate_rate_change(top, PRE_RATE_CHANGE);
-       if (fail_clk) {
-               pr_debug("%s: failed to set %s rate\n", __func__,
-                               fail_clk->name);
-               clk_propagate_rate_change(top, ABORT_RATE_CHANGE);
-               return -EBUSY;
-       }
+       return false;
+}
+EXPORT_SYMBOL_GPL(clk_is_match);
 
-       /* change the rates */
-       clk_change_rate(top);
+/***        debugfs support        ***/
 
-       core->req_rate = req_rate;
+#ifdef CONFIG_DEBUG_FS
+#include <linux/debugfs.h>
 
-       return ret;
-}
+static struct dentry *rootdir;
+static int inited = 0;
+static DEFINE_MUTEX(clk_debug_lock);
+static HLIST_HEAD(clk_debug_list);
 
-/**
- * clk_set_rate - specify a new rate for clk
- * @clk: the clk whose rate is being changed
- * @rate: the new rate for clk
- *
- * In the simplest case clk_set_rate will only adjust the rate of clk.
- *
- * Setting the CLK_SET_RATE_PARENT flag allows the rate change operation to
- * propagate up to clk's parent; whether or not this happens depends on the
- * outcome of clk's .round_rate implementation.  If *parent_rate is unchanged
- * after calling .round_rate then upstream parent propagation is ignored.  If
- * *parent_rate comes back with a new rate for clk's parent then we propagate
- * up to clk's parent and set its rate.  Upward propagation will continue
- * until either a clk does not support the CLK_SET_RATE_PARENT flag or
- * .round_rate stops requesting changes to clk's parent_rate.
- *
- * Rate changes are accomplished via tree traversal that also recalculates the
- * rates for the clocks and fires off POST_RATE_CHANGE notifiers.
- *
- * Returns 0 on success, -EERROR otherwise.
- */
-int clk_set_rate(struct clk *clk, unsigned long rate)
+static struct hlist_head *all_lists[] = {
+       &clk_root_list,
+       &clk_orphan_list,
+       NULL,
+};
+
+static struct hlist_head *orphan_list[] = {
+       &clk_orphan_list,
+       NULL,
+};
+
+static void clk_summary_show_one(struct seq_file *s, struct clk_core *c,
+                                int level)
 {
-       int ret;
+       if (!c)
+               return;
 
-       if (!clk)
-               return 0;
+       seq_printf(s, "%*s%-*s %11d %12d %11lu %10lu %-3d\n",
+                  level * 3 + 1, "",
+                  30 - level * 3, c->name,
+                  c->enable_count, c->prepare_count, clk_core_get_rate(c),
+                  clk_core_get_accuracy(c), clk_core_get_phase(c));
+}
 
-       /* prevent racing with updates to the clock topology */
-       clk_prepare_lock();
+static void clk_summary_show_subtree(struct seq_file *s, struct clk_core *c,
+                                    int level)
+{
+       struct clk_core *child;
 
-       ret = clk_core_set_rate_nolock(clk->core, rate);
+       if (!c)
+               return;
 
-       clk_prepare_unlock();
+       clk_summary_show_one(s, c, level);
 
-       return ret;
+       hlist_for_each_entry(child, &c->children, child_node)
+               clk_summary_show_subtree(s, child, level + 1);
 }
-EXPORT_SYMBOL_GPL(clk_set_rate);
 
-/**
- * clk_set_rate_range - set a rate range for a clock source
- * @clk: clock source
- * @min: desired minimum clock rate in Hz, inclusive
- * @max: desired maximum clock rate in Hz, inclusive
- *
- * Returns success (0) or negative errno.
- */
-int clk_set_rate_range(struct clk *clk, unsigned long min, unsigned long max)
+static int clk_summary_show(struct seq_file *s, void *data)
 {
-       int ret = 0;
-
-       if (!clk)
-               return 0;
+       struct clk_core *c;
+       struct hlist_head **lists = (struct hlist_head **)s->private;
 
-       if (min > max) {
-               pr_err("%s: clk %s dev %s con %s: invalid range [%lu, %lu]\n",
-                      __func__, clk->core->name, clk->dev_id, clk->con_id,
-                      min, max);
-               return -EINVAL;
-       }
+       seq_puts(s, "   clock                         enable_cnt  prepare_cnt        rate   accuracy   phase\n");
+       seq_puts(s, "----------------------------------------------------------------------------------------\n");
 
        clk_prepare_lock();
 
-       if (min != clk->min_rate || max != clk->max_rate) {
-               clk->min_rate = min;
-               clk->max_rate = max;
-               ret = clk_core_set_rate_nolock(clk->core, clk->core->req_rate);
-       }
+       for (; *lists; lists++)
+               hlist_for_each_entry(c, *lists, child_node)
+                       clk_summary_show_subtree(s, c, 0);
 
        clk_prepare_unlock();
 
-       return ret;
+       return 0;
 }
-EXPORT_SYMBOL_GPL(clk_set_rate_range);
-
-/**
- * clk_set_min_rate - set a minimum clock rate for a clock source
- * @clk: clock source
- * @rate: desired minimum clock rate in Hz, inclusive
- *
- * Returns success (0) or negative errno.
- */
-int clk_set_min_rate(struct clk *clk, unsigned long rate)
-{
-       if (!clk)
-               return 0;
 
-       return clk_set_rate_range(clk, rate, clk->max_rate);
-}
-EXPORT_SYMBOL_GPL(clk_set_min_rate);
 
-/**
- * clk_set_max_rate - set a maximum clock rate for a clock source
- * @clk: clock source
- * @rate: desired maximum clock rate in Hz, inclusive
- *
- * Returns success (0) or negative errno.
- */
-int clk_set_max_rate(struct clk *clk, unsigned long rate)
+static int clk_summary_open(struct inode *inode, struct file *file)
 {
-       if (!clk)
-               return 0;
-
-       return clk_set_rate_range(clk, clk->min_rate, rate);
+       return single_open(file, clk_summary_show, inode->i_private);
 }
-EXPORT_SYMBOL_GPL(clk_set_max_rate);
 
-/**
- * clk_get_parent - return the parent of a clk
- * @clk: the clk whose parent gets returned
- *
- * Simply returns clk->parent.  Returns NULL if clk is NULL.
- */
-struct clk *clk_get_parent(struct clk *clk)
-{
-       struct clk *parent;
+static const struct file_operations clk_summary_fops = {
+       .open           = clk_summary_open,
+       .read           = seq_read,
+       .llseek         = seq_lseek,
+       .release        = single_release,
+};
 
-       clk_prepare_lock();
-       parent = __clk_get_parent(clk);
-       clk_prepare_unlock();
+static void clk_dump_one(struct seq_file *s, struct clk_core *c, int level)
+{
+       if (!c)
+               return;
 
-       return parent;
+       seq_printf(s, "\"%s\": { ", c->name);
+       seq_printf(s, "\"enable_count\": %d,", c->enable_count);
+       seq_printf(s, "\"prepare_count\": %d,", c->prepare_count);
+       seq_printf(s, "\"rate\": %lu", clk_core_get_rate(c));
+       seq_printf(s, "\"accuracy\": %lu", clk_core_get_accuracy(c));
+       seq_printf(s, "\"phase\": %d", clk_core_get_phase(c));
 }
-EXPORT_SYMBOL_GPL(clk_get_parent);
 
-/*
- * .get_parent is mandatory for clocks with multiple possible parents.  It is
- * optional for single-parent clocks.  Always call .get_parent if it is
- * available and WARN if it is missing for multi-parent clocks.
- *
- * For single-parent clocks without .get_parent, first check to see if the
- * .parents array exists, and if so use it to avoid an expensive tree
- * traversal.  If .parents does not exist then walk the tree.
- */
-static struct clk_core *__clk_init_parent(struct clk_core *core)
+static void clk_dump_subtree(struct seq_file *s, struct clk_core *c, int level)
 {
-       struct clk_core *ret = NULL;
-       u8 index;
+       struct clk_core *child;
 
-       /* handle the trivial cases */
+       if (!c)
+               return;
 
-       if (!core->num_parents)
-               goto out;
+       clk_dump_one(s, c, level);
 
-       if (core->num_parents == 1) {
-               if (IS_ERR_OR_NULL(core->parent))
-                       core->parent = clk_core_lookup(core->parent_names[0]);
-               ret = core->parent;
-               goto out;
+       hlist_for_each_entry(child, &c->children, child_node) {
+               seq_printf(s, ",");
+               clk_dump_subtree(s, child, level + 1);
        }
 
-       if (!core->ops->get_parent) {
-               WARN(!core->ops->get_parent,
-                       "%s: multi-parent clocks must implement .get_parent\n",
-                       __func__);
-               goto out;
-       };
-
-       /*
-        * Do our best to cache parent clocks in core->parents.  This prevents
-        * unnecessary and expensive lookups.  We don't set core->parent here;
-        * that is done by the calling function.
-        */
-
-       index = core->ops->get_parent(core->hw);
-
-       if (!core->parents)
-               core->parents =
-                       kcalloc(core->num_parents, sizeof(struct clk *),
-                                       GFP_KERNEL);
-
-       ret = clk_core_get_parent_by_index(core, index);
-
-out:
-       return ret;
-}
-
-static void clk_core_reparent(struct clk_core *core,
-                                 struct clk_core *new_parent)
-{
-       clk_reparent(core, new_parent);
-       __clk_recalc_accuracies(core);
-       __clk_recalc_rates(core, POST_RATE_CHANGE);
+       seq_printf(s, "}");
 }
 
-/**
- * clk_has_parent - check if a clock is a possible parent for another
- * @clk: clock source
- * @parent: parent clock source
- *
- * This function can be used in drivers that need to check that a clock can be
- * the parent of another without actually changing the parent.
- *
- * Returns true if @parent is a possible parent for @clk, false otherwise.
- */
-bool clk_has_parent(struct clk *clk, struct clk *parent)
+static int clk_dump(struct seq_file *s, void *data)
 {
-       struct clk_core *core, *parent_core;
-       unsigned int i;
+       struct clk_core *c;
+       bool first_node = true;
+       struct hlist_head **lists = (struct hlist_head **)s->private;
 
-       /* NULL clocks should be nops, so return success if either is NULL. */
-       if (!clk || !parent)
-               return true;
+       seq_printf(s, "{");
 
-       core = clk->core;
-       parent_core = parent->core;
+       clk_prepare_lock();
 
-       /* Optimize for the case where the parent is already the parent. */
-       if (core->parent == parent_core)
-               return true;
+       for (; *lists; lists++) {
+               hlist_for_each_entry(c, *lists, child_node) {
+                       if (!first_node)
+                               seq_puts(s, ",");
+                       first_node = false;
+                       clk_dump_subtree(s, c, 0);
+               }
+       }
 
-       for (i = 0; i < core->num_parents; i++)
-               if (strcmp(core->parent_names[i], parent_core->name) == 0)
-                       return true;
+       clk_prepare_unlock();
 
-       return false;
+       seq_printf(s, "}");
+       return 0;
 }
-EXPORT_SYMBOL_GPL(clk_has_parent);
 
-static int clk_core_set_parent(struct clk_core *core, struct clk_core *parent)
+
+static int clk_dump_open(struct inode *inode, struct file *file)
 {
-       int ret = 0;
-       int p_index = 0;
-       unsigned long p_rate = 0;
+       return single_open(file, clk_dump, inode->i_private);
+}
 
-       if (!core)
-               return 0;
+static const struct file_operations clk_dump_fops = {
+       .open           = clk_dump_open,
+       .read           = seq_read,
+       .llseek         = seq_lseek,
+       .release        = single_release,
+};
 
-       /* prevent racing with updates to the clock topology */
-       clk_prepare_lock();
+static int clk_debug_create_one(struct clk_core *core, struct dentry *pdentry)
+{
+       struct dentry *d;
+       int ret = -ENOMEM;
 
-       if (core->parent == parent)
+       if (!core || !pdentry) {
+               ret = -EINVAL;
                goto out;
+       }
 
-       /* verify ops for for multi-parent clks */
-       if ((core->num_parents > 1) && (!core->ops->set_parent)) {
-               ret = -ENOSYS;
+       d = debugfs_create_dir(core->name, pdentry);
+       if (!d)
                goto out;
-       }
 
-       /* check that we are allowed to re-parent if the clock is in use */
-       if ((core->flags & CLK_SET_PARENT_GATE) && core->prepare_count) {
-               ret = -EBUSY;
-               goto out;
-       }
+       core->dentry = d;
+
+       d = debugfs_create_u32("clk_rate", S_IRUGO, core->dentry,
+                       (u32 *)&core->rate);
+       if (!d)
+               goto err_out;
+
+       d = debugfs_create_u32("clk_accuracy", S_IRUGO, core->dentry,
+                       (u32 *)&core->accuracy);
+       if (!d)
+               goto err_out;
+
+       d = debugfs_create_u32("clk_phase", S_IRUGO, core->dentry,
+                       (u32 *)&core->phase);
+       if (!d)
+               goto err_out;
 
-       /* try finding the new parent index */
-       if (parent) {
-               p_index = clk_fetch_parent_index(core, parent);
-               p_rate = parent->rate;
-               if (p_index < 0) {
-                       pr_debug("%s: clk %s can not be parent of clk %s\n",
-                                       __func__, parent->name, core->name);
-                       ret = p_index;
-                       goto out;
-               }
-       }
+       d = debugfs_create_x32("clk_flags", S_IRUGO, core->dentry,
+                       (u32 *)&core->flags);
+       if (!d)
+               goto err_out;
 
-       /* propagate PRE_RATE_CHANGE notifications */
-       ret = __clk_speculate_rates(core, p_rate);
+       d = debugfs_create_u32("clk_prepare_count", S_IRUGO, core->dentry,
+                       (u32 *)&core->prepare_count);
+       if (!d)
+               goto err_out;
 
-       /* abort if a driver objects */
-       if (ret & NOTIFY_STOP_MASK)
-               goto out;
+       d = debugfs_create_u32("clk_enable_count", S_IRUGO, core->dentry,
+                       (u32 *)&core->enable_count);
+       if (!d)
+               goto err_out;
 
-       /* do the re-parent */
-       ret = __clk_set_parent(core, parent, p_index);
+       d = debugfs_create_u32("clk_notifier_count", S_IRUGO, core->dentry,
+                       (u32 *)&core->notifier_count);
+       if (!d)
+               goto err_out;
 
-       /* propagate rate an accuracy recalculation accordingly */
-       if (ret) {
-               __clk_recalc_rates(core, ABORT_RATE_CHANGE);
-       } else {
-               __clk_recalc_rates(core, POST_RATE_CHANGE);
-               __clk_recalc_accuracies(core);
+       if (core->ops->debug_init) {
+               ret = core->ops->debug_init(core->hw, core->dentry);
+               if (ret)
+                       goto err_out;
        }
 
-out:
-       clk_prepare_unlock();
+       ret = 0;
+       goto out;
 
+err_out:
+       debugfs_remove_recursive(core->dentry);
+       core->dentry = NULL;
+out:
        return ret;
 }
 
 /**
- * clk_set_parent - switch the parent of a mux clk
- * @clk: the mux clk whose input we are switching
- * @parent: the new input to clk
- *
- * Re-parent clk to use parent as its new input source.  If clk is in
- * prepared state, the clk will get enabled for the duration of this call. If
- * that's not acceptable for a specific clk (Eg: the consumer can't handle
- * that, the reparenting is glitchy in hardware, etc), use the
- * CLK_SET_PARENT_GATE flag to allow reparenting only when clk is unprepared.
- *
- * After successfully changing clk's parent clk_set_parent will update the
- * clk topology, sysfs topology and propagate rate recalculation via
- * __clk_recalc_rates.
+ * clk_debug_register - add a clk node to the debugfs clk tree
+ * @core: the clk being added to the debugfs clk tree
  *
- * Returns 0 on success, -EERROR otherwise.
+ * Dynamically adds a clk to the debugfs clk tree if debugfs has been
+ * initialized.  Otherwise it bails out early since the debugfs clk tree
+ * will be created lazily by clk_debug_init as part of a late_initcall.
  */
-int clk_set_parent(struct clk *clk, struct clk *parent)
+static int clk_debug_register(struct clk_core *core)
 {
-       if (!clk)
-               return 0;
+       int ret = 0;
 
-       return clk_core_set_parent(clk->core, parent ? parent->core : NULL);
+       mutex_lock(&clk_debug_lock);
+       hlist_add_head(&core->debug_node, &clk_debug_list);
+
+       if (!inited)
+               goto unlock;
+
+       ret = clk_debug_create_one(core, rootdir);
+unlock:
+       mutex_unlock(&clk_debug_lock);
+
+       return ret;
 }
-EXPORT_SYMBOL_GPL(clk_set_parent);
 
-/**
- * clk_set_phase - adjust the phase shift of a clock signal
- * @clk: clock signal source
- * @degrees: number of degrees the signal is shifted
- *
- * Shifts the phase of a clock signal by the specified
- * degrees. Returns 0 on success, -EERROR otherwise.
- *
- * This function makes no distinction about the input or reference
- * signal that we adjust the clock signal phase against. For example
- * phase locked-loop clock signal generators we may shift phase with
- * respect to feedback clock signal input, but for other cases the
- * clock phase may be shifted with respect to some other, unspecified
- * signal.
+ /**
+ * clk_debug_unregister - remove a clk node from the debugfs clk tree
+ * @core: the clk being removed from the debugfs clk tree
  *
- * Additionally the concept of phase shift does not propagate through
- * the clock tree hierarchy, which sets it apart from clock rates and
- * clock accuracy. A parent clock phase attribute does not have an
- * impact on the phase attribute of a child clock.
+ * Dynamically removes a clk and all it's children clk nodes from the
+ * debugfs clk tree if clk->dentry points to debugfs created by
+ * clk_debug_register in __clk_init.
  */
-int clk_set_phase(struct clk *clk, int degrees)
+static void clk_debug_unregister(struct clk_core *core)
 {
-       int ret = -EINVAL;
+       mutex_lock(&clk_debug_lock);
+       hlist_del_init(&core->debug_node);
+       debugfs_remove_recursive(core->dentry);
+       core->dentry = NULL;
+       mutex_unlock(&clk_debug_lock);
+}
 
-       if (!clk)
-               return 0;
+struct dentry *clk_debugfs_add_file(struct clk_hw *hw, char *name, umode_t mode,
+                               void *data, const struct file_operations *fops)
+{
+       struct dentry *d = NULL;
 
-       /* sanity check degrees */
-       degrees %= 360;
-       if (degrees < 0)
-               degrees += 360;
+       if (hw->core->dentry)
+               d = debugfs_create_file(name, mode, hw->core->dentry, data,
+                                       fops);
 
-       clk_prepare_lock();
+       return d;
+}
+EXPORT_SYMBOL_GPL(clk_debugfs_add_file);
 
-       trace_clk_set_phase(clk->core, degrees);
+/**
+ * clk_debug_init - lazily create the debugfs clk tree visualization
+ *
+ * clks are often initialized very early during boot before memory can
+ * be dynamically allocated and well before debugfs is setup.
+ * clk_debug_init walks the clk tree hierarchy while holding
+ * prepare_lock and creates the topology as part of a late_initcall,
+ * thus insuring that clks initialized very early will still be
+ * represented in the debugfs clk tree.  This function should only be
+ * called once at boot-time, and all other clks added dynamically will
+ * be done so with clk_debug_register.
+ */
+static int __init clk_debug_init(void)
+{
+       struct clk_core *core;
+       struct dentry *d;
 
-       if (clk->core->ops->set_phase)
-               ret = clk->core->ops->set_phase(clk->core->hw, degrees);
+       rootdir = debugfs_create_dir("clk", NULL);
 
-       trace_clk_set_phase_complete(clk->core, degrees);
+       if (!rootdir)
+               return -ENOMEM;
 
-       if (!ret)
-               clk->core->phase = degrees;
+       d = debugfs_create_file("clk_summary", S_IRUGO, rootdir, &all_lists,
+                               &clk_summary_fops);
+       if (!d)
+               return -ENOMEM;
 
-       clk_prepare_unlock();
+       d = debugfs_create_file("clk_dump", S_IRUGO, rootdir, &all_lists,
+                               &clk_dump_fops);
+       if (!d)
+               return -ENOMEM;
 
-       return ret;
-}
-EXPORT_SYMBOL_GPL(clk_set_phase);
+       d = debugfs_create_file("clk_orphan_summary", S_IRUGO, rootdir,
+                               &orphan_list, &clk_summary_fops);
+       if (!d)
+               return -ENOMEM;
 
-static int clk_core_get_phase(struct clk_core *core)
-{
-       int ret;
+       d = debugfs_create_file("clk_orphan_dump", S_IRUGO, rootdir,
+                               &orphan_list, &clk_dump_fops);
+       if (!d)
+               return -ENOMEM;
 
-       clk_prepare_lock();
-       ret = core->phase;
-       clk_prepare_unlock();
+       mutex_lock(&clk_debug_lock);
+       hlist_for_each_entry(core, &clk_debug_list, debug_node)
+               clk_debug_create_one(core, rootdir);
 
-       return ret;
-}
-EXPORT_SYMBOL_GPL(clk_get_phase);
+       inited = 1;
+       mutex_unlock(&clk_debug_lock);
 
-/**
- * clk_get_phase - return the phase shift of a clock signal
- * @clk: clock signal source
- *
- * Returns the phase shift of a clock node in degrees, otherwise returns
- * -EERROR.
- */
-int clk_get_phase(struct clk *clk)
+       return 0;
+}
+late_initcall(clk_debug_init);
+#else
+static inline int clk_debug_register(struct clk_core *core) { return 0; }
+static inline void clk_debug_reparent(struct clk_core *core,
+                                     struct clk_core *new_parent)
 {
-       if (!clk)
-               return 0;
-
-       return clk_core_get_phase(clk->core);
 }
-
-/**
- * clk_is_match - check if two clk's point to the same hardware clock
- * @p: clk compared against q
- * @q: clk compared against p
- *
- * Returns true if the two struct clk pointers both point to the same hardware
- * clock node. Put differently, returns true if struct clk *p and struct clk *q
- * share the same struct clk_core object.
- *
- * Returns false otherwise. Note that two NULL clks are treated as matching.
- */
-bool clk_is_match(const struct clk *p, const struct clk *q)
+static inline void clk_debug_unregister(struct clk_core *core)
 {
-       /* trivial case: identical struct clk's or both NULL */
-       if (p == q)
-               return true;
-
-       /* true if clk->core pointers match. Avoid derefing garbage */
-       if (!IS_ERR_OR_NULL(p) && !IS_ERR_OR_NULL(q))
-               if (p->core == q->core)
-                       return true;
-
-       return false;
 }
-EXPORT_SYMBOL_GPL(clk_is_match);
+#endif
 
 /**
  * __clk_init - initialize the data structures in a struct clk