arch/arm/common/clkdev.c

   1 /*
   2  *  arch/arm/common/clkdev.c
   3  *
   4  *  Copyright (C) 2008 Russell King.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * Helper for the clk API to assist looking up a struct clk.
  11  */
  12 #include <linux/module.h>
  13 #include <linux/kernel.h>
  14 #include <linux/device.h>
  15 #include <linux/list.h>
  16 #include <linux/errno.h>
  17 #include <linux/err.h>
  18 #include <linux/string.h>
  19 #include <linux/mutex.h>
  20 #include <linux/clk.h>
  21 #include <linux/slab.h>
  22
  23 #include <asm/clkdev.h>
  24 #include <mach/clkdev.h>
  25
  26 static LIST_HEAD(clocks);
  27 static DEFINE_MUTEX(clocks_mutex);
  28
  29 /*
  30  * Find the correct struct clk for the device and connection ID.
  31  * We do slightly fuzzy matching here:
  32  *  An entry with a NULL ID is assumed to be a wildcard.
  33  *  If an entry has a device ID, it must match
  34  *  If an entry has a connection ID, it must match
  35  * Then we take the most specific entry - with the following
  36  * order of precedence: dev+con > dev only > con only.
  37  */
  38 static struct clk *clk_find(const char *dev_id, const char *con_id)
  39 {
  40         struct clk_lookup *p;
  41         struct clk *clk = NULL;
  42         int match, best = 0;
  43
  44         list_for_each_entry(p, &clocks, node) {
  45                 match = 0;
  46                 if (p->dev_id) {
  47                         if (!dev_id || strcmp(p->dev_id, dev_id))
  48                                 continue;
  49                         match += 2;
  50                 }
  51                 if (p->con_id) {
  52                         if (!con_id || strcmp(p->con_id, con_id))
  53                                 continue;
  54                         match += 1;
  55                 }
  56                 if (match == 0)
  57                         continue;
  58
  59                 if (match > best) {
  60                         clk = p->clk;
  61                         best = match;
  62                 }
  63         }
  64         return clk;
  65 }
  66
  67 struct clk *clk_get_sys(const char *dev_id, const char *con_id)
  68 {
  69         struct clk *clk;
  70
  71         mutex_lock(&clocks_mutex);
  72         clk = clk_find(dev_id, con_id);
  73         if (clk && !__clk_get(clk))
  74                 clk = NULL;
  75         mutex_unlock(&clocks_mutex);
  76
  77         return clk ? clk : ERR_PTR(-ENOENT);
  78 }
  79 EXPORT_SYMBOL(clk_get_sys);
  80
  81 struct clk *clk_get(struct device *dev, const char *con_id)
  82 {
  83         const char *dev_id = dev ? dev_name(dev) : NULL;
  84
  85         return clk_get_sys(dev_id, con_id);
  86 }
  87 EXPORT_SYMBOL(clk_get);
  88
  89 void clk_put(struct clk *clk)
  90 {
  91         __clk_put(clk);
  92 }
  93 EXPORT_SYMBOL(clk_put);
  94
  95 void clkdev_add(struct clk_lookup *cl)
  96 {
  97         mutex_lock(&clocks_mutex);
  98         list_add_tail(&cl->node, &clocks);
  99         mutex_unlock(&clocks_mutex);
 100 }
 101 EXPORT_SYMBOL(clkdev_add);
 102
 103 void __init clkdev_add_table(struct clk_lookup *cl, size_t num)
 104 {
 105         mutex_lock(&clocks_mutex);
 106         while (num--) {
 107                 list_add_tail(&cl->node, &clocks);
 108                 cl++;
 109         }
 110         mutex_unlock(&clocks_mutex);
 111 }
 112
 113 #define MAX_DEV_ID      20
 114 #define MAX_CON_ID      16
 115
 116 struct clk_lookup_alloc {
 117         struct clk_lookup cl;
 118         char    dev_id[MAX_DEV_ID];
 119         char    con_id[MAX_CON_ID];
 120 };
 121
 122 struct clk_lookup *clkdev_alloc(struct clk *clk, const char *con_id,
 123         const char *dev_fmt, ...)
 124 {
 125         struct clk_lookup_alloc *cla;
 126
 127         cla = kzalloc(sizeof(*cla), GFP_KERNEL);
 128         if (!cla)
 129                 return NULL;
 130
 131         cla->cl.clk = clk;
 132         if (con_id) {
 133                 strlcpy(cla->con_id, con_id, sizeof(cla->con_id));
 134                 cla->cl.con_id = cla->con_id;
 135         }
 136
 137         if (dev_fmt) {
 138                 va_list ap;
 139
 140                 va_start(ap, dev_fmt);
 141                 vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
 142                 cla->cl.dev_id = cla->dev_id;
 143                 va_end(ap);
 144         }
 145
 146         return &cla->cl;
 147 }
 148 EXPORT_SYMBOL(clkdev_alloc);
 149
 150 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 151         struct device *dev)
 152 {
 153         struct clk *r = clk_get(dev, id);
 154         struct clk_lookup *l;
 155
 156         if (IS_ERR(r))
 157                 return PTR_ERR(r);
 158
 159         l = clkdev_alloc(r, alias, alias_dev_name);
 160         clk_put(r);
 161         if (!l)
 162                 return -ENODEV;
 163         clkdev_add(l);
 164         return 0;
 165 }
 166 EXPORT_SYMBOL(clk_add_alias);
 167
 168 /*
 169  * clkdev_drop - remove a clock dynamically allocated
 170  */
 171 void clkdev_drop(struct clk_lookup *cl)
 172 {
 173         mutex_lock(&clocks_mutex);
 174         list_del(&cl->node);
 175         mutex_unlock(&clocks_mutex);
 176         kfree(cl);
 177 }
 178 EXPORT_SYMBOL(clkdev_drop);