include/linux/clk.h

   1 /*
   2  *  linux/include/linux/clk.h
   3  *
   4  *  Copyright (C) 2004 ARM Limited.
   5  *  Written by Deep Blue Solutions Limited.
   6  *  Copyright (C) 2011-2012 Linaro Ltd <mturquette@linaro.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12 #ifndef __LINUX_CLK_H
  13 #define __LINUX_CLK_H
  14
  15 #include <linux/err.h>
  16 #include <linux/kernel.h>
  17 #include <linux/notifier.h>
  18
  19 struct device;
  20
  21 struct clk;
  22
  23 #ifdef CONFIG_COMMON_CLK
  24
  25 /**
  26  * DOC: clk notifier callback types
  27  *
  28  * PRE_RATE_CHANGE - called immediately before the clk rate is changed,
  29  *     to indicate that the rate change will proceed.  Drivers must
  30  *     immediately terminate any operations that will be affected by the
  31  *     rate change.  Callbacks may either return NOTIFY_DONE or
  32  *     NOTIFY_STOP.
  33  *
  34  * ABORT_RATE_CHANGE: called if the rate change failed for some reason
  35  *     after PRE_RATE_CHANGE.  In this case, all registered notifiers on
  36  *     the clk will be called with ABORT_RATE_CHANGE. Callbacks must
  37  *     always return NOTIFY_DONE.
  38  *
  39  * POST_RATE_CHANGE - called after the clk rate change has successfully
  40  *     completed.  Callbacks must always return NOTIFY_DONE.
  41  *
  42  */
  43 #define PRE_RATE_CHANGE                 BIT(0)
  44 #define POST_RATE_CHANGE                BIT(1)
  45 #define ABORT_RATE_CHANGE               BIT(2)
  46
  47 /**
  48  * struct clk_notifier - associate a clk with a notifier
  49  * @clk: struct clk * to associate the notifier with
  50  * @notifier_head: a blocking_notifier_head for this clk
  51  * @node: linked list pointers
  52  *
  53  * A list of struct clk_notifier is maintained by the notifier code.
  54  * An entry is created whenever code registers the first notifier on a
  55  * particular @clk.  Future notifiers on that @clk are added to the
  56  * @notifier_head.
  57  */
  58 struct clk_notifier {
  59         struct clk                      *clk;
  60         struct srcu_notifier_head       notifier_head;
  61         struct list_head                node;
  62 };
  63
  64 /**
  65  * struct clk_notifier_data - rate data to pass to the notifier callback
  66  * @clk: struct clk * being changed
  67  * @old_rate: previous rate of this clk
  68  * @new_rate: new rate of this clk
  69  *
  70  * For a pre-notifier, old_rate is the clk's rate before this rate
  71  * change, and new_rate is what the rate will be in the future.  For a
  72  * post-notifier, old_rate and new_rate are both set to the clk's
  73  * current rate (this was done to optimize the implementation).
  74  */
  75 struct clk_notifier_data {
  76         struct clk              *clk;
  77         unsigned long           old_rate;
  78         unsigned long           new_rate;
  79 };
  80
  81 int clk_notifier_register(struct clk *clk, struct notifier_block *nb);
  82
  83 int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb);
  84
  85 #endif
  86
  87 /**
  88  * clk_get - lookup and obtain a reference to a clock producer.
  89  * @dev: device for clock "consumer"
  90  * @id: clock consumer ID
  91  *
  92  * Returns a struct clk corresponding to the clock producer, or
  93  * valid IS_ERR() condition containing errno.  The implementation
  94  * uses @dev and @id to determine the clock consumer, and thereby
  95  * the clock producer.  (IOW, @id may be identical strings, but
  96  * clk_get may return different clock producers depending on @dev.)
  97  *
  98  * Drivers must assume that the clock source is not enabled.
  99  *
 100  * clk_get should not be called from within interrupt context.
 101  */
 102 struct clk *clk_get(struct device *dev, const char *id);
 103
 104 /**
 105  * devm_clk_get - lookup and obtain a managed reference to a clock producer.
 106  * @dev: device for clock "consumer"
 107  * @id: clock consumer ID
 108  *
 109  * Returns a struct clk corresponding to the clock producer, or
 110  * valid IS_ERR() condition containing errno.  The implementation
 111  * uses @dev and @id to determine the clock consumer, and thereby
 112  * the clock producer.  (IOW, @id may be identical strings, but
 113  * clk_get may return different clock producers depending on @dev.)
 114  *
 115  * Drivers must assume that the clock source is not enabled.
 116  *
 117  * devm_clk_get should not be called from within interrupt context.
 118  *
 119  * The clock will automatically be freed when the device is unbound
 120  * from the bus.
 121  */
 122 struct clk *devm_clk_get(struct device *dev, const char *id);
 123
 124 /**
 125  * clk_prepare - prepare a clock source
 126  * @clk: clock source
 127  *
 128  * This prepares the clock source for use.
 129  *
 130  * Must not be called from within atomic context.
 131  */
 132 #ifdef CONFIG_HAVE_CLK_PREPARE
 133 int clk_prepare(struct clk *clk);
 134 #else
 135 static inline int clk_prepare(struct clk *clk)
 136 {
 137         might_sleep();
 138         return 0;
 139 }
 140 #endif
 141
 142 /**
 143  * clk_enable - inform the system when the clock source should be running.
 144  * @clk: clock source
 145  *
 146  * If the clock can not be enabled/disabled, this should return success.
 147  *
 148  * May be called from atomic contexts.
 149  *
 150  * Returns success (0) or negative errno.
 151  */
 152 int clk_enable(struct clk *clk);
 153
 154 /**
 155  * clk_disable - inform the system when the clock source is no longer required.
 156  * @clk: clock source
 157  *
 158  * Inform the system that a clock source is no longer required by
 159  * a driver and may be shut down.
 160  *
 161  * May be called from atomic contexts.
 162  *
 163  * Implementation detail: if the clock source is shared between
 164  * multiple drivers, clk_enable() calls must be balanced by the
 165  * same number of clk_disable() calls for the clock source to be
 166  * disabled.
 167  */
 168 void clk_disable(struct clk *clk);
 169
 170
 171 /**
 172  * clk_unprepare - undo preparation of a clock source
 173  * @clk: clock source
 174  *
 175  * This undoes a previously prepared clock.  The caller must balance
 176  * the number of prepare and unprepare calls.
 177  *
 178  * Must not be called from within atomic context.
 179  */
 180 #ifdef CONFIG_HAVE_CLK_PREPARE
 181 void clk_unprepare(struct clk *clk);
 182 #else
 183 static inline void clk_unprepare(struct clk *clk)
 184 {
 185         might_sleep();
 186 }
 187 #endif
 188
 189 /* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
 190 static inline int clk_prepare_enable(struct clk *clk)
 191 {
 192         int ret;
 193
 194         ret = clk_prepare(clk);
 195         if (ret)
 196                 return ret;
 197         ret = clk_enable(clk);
 198         if (ret)
 199                 clk_unprepare(clk);
 200
 201         return ret;
 202 }
 203
 204 /* clk_disable_unprepare helps cases using clk_disable in non-atomic context. */
 205 static inline void clk_disable_unprepare(struct clk *clk)
 206 {
 207         clk_disable(clk);
 208         clk_unprepare(clk);
 209 }
 210
 211 /**
 212  * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
 213  *                This is only valid once the clock source has been enabled.
 214  * @clk: clock source
 215  */
 216 unsigned long clk_get_rate(struct clk *clk);
 217
 218 /**
 219  * clk_put      - "free" the clock source
 220  * @clk: clock source
 221  *
 222  * Note: drivers must ensure that all clk_enable calls made on this
 223  * clock source are balanced by clk_disable calls prior to calling
 224  * this function.
 225  *
 226  * clk_put should not be called from within interrupt context.
 227  */
 228 void clk_put(struct clk *clk);
 229
 230 /**
 231  * devm_clk_put - "free" a managed clock source
 232  * @dev: device used to acuqire the clock
 233  * @clk: clock source acquired with devm_clk_get()
 234  *
 235  * Note: drivers must ensure that all clk_enable calls made on this
 236  * clock source are balanced by clk_disable calls prior to calling
 237  * this function.
 238  *
 239  * clk_put should not be called from within interrupt context.
 240  */
 241 void devm_clk_put(struct device *dev, struct clk *clk);
 242
 243 /*
 244  * The remaining APIs are optional for machine class support.
 245  */
 246
 247
 248 /**
 249  * clk_round_rate - adjust a rate to the exact rate a clock can provide
 250  * @clk: clock source
 251  * @rate: desired clock rate in Hz
 252  *
 253  * Returns rounded clock rate in Hz, or negative errno.
 254  */
 255 long clk_round_rate(struct clk *clk, unsigned long rate);
 256
 257 /**
 258  * clk_set_rate - set the clock rate for a clock source
 259  * @clk: clock source
 260  * @rate: desired clock rate in Hz
 261  *
 262  * Returns success (0) or negative errno.
 263  */
 264 int clk_set_rate(struct clk *clk, unsigned long rate);
 265
 266 /**
 267  * clk_set_parent - set the parent clock source for this clock
 268  * @clk: clock source
 269  * @parent: parent clock source
 270  *
 271  * Returns success (0) or negative errno.
 272  */
 273 int clk_set_parent(struct clk *clk, struct clk *parent);
 274
 275 /**
 276  * clk_get_parent - get the parent clock source for this clock
 277  * @clk: clock source
 278  *
 279  * Returns struct clk corresponding to parent clock source, or
 280  * valid IS_ERR() condition containing errno.
 281  */
 282 struct clk *clk_get_parent(struct clk *clk);
 283
 284 /**
 285  * clk_get_sys - get a clock based upon the device name
 286  * @dev_id: device name
 287  * @con_id: connection ID
 288  *
 289  * Returns a struct clk corresponding to the clock producer, or
 290  * valid IS_ERR() condition containing errno.  The implementation
 291  * uses @dev_id and @con_id to determine the clock consumer, and
 292  * thereby the clock producer. In contrast to clk_get() this function
 293  * takes the device name instead of the device itself for identification.
 294  *
 295  * Drivers must assume that the clock source is not enabled.
 296  *
 297  * clk_get_sys should not be called from within interrupt context.
 298  */
 299 struct clk *clk_get_sys(const char *dev_id, const char *con_id);
 300
 301 /**
 302  * clk_add_alias - add a new clock alias
 303  * @alias: name for clock alias
 304  * @alias_dev_name: device name
 305  * @id: platform specific clock name
 306  * @dev: device
 307  *
 308  * Allows using generic clock names for drivers by adding a new alias.
 309  * Assumes clkdev, see clkdev.h for more info.
 310  */
 311 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 312                         struct device *dev);
 313
 314 struct device_node;
 315 struct of_phandle_args;
 316
 317 #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
 318 struct clk *of_clk_get(struct device_node *np, int index);
 319 struct clk *of_clk_get_by_name(struct device_node *np, const char *name);
 320 struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec);
 321 #else
 322 static inline struct clk *of_clk_get(struct device_node *np, int index)
 323 {
 324         return ERR_PTR(-ENOENT);
 325 }
 326 static inline struct clk *of_clk_get_by_name(struct device_node *np,
 327                                              const char *name)
 328 {
 329         return ERR_PTR(-ENOENT);
 330 }
 331 #endif
 332
 333 #endif