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, NOTIFY_OK,
  32  *     NOTIFY_STOP or NOTIFY_BAD.
  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 or NOTIFY_OK.
  38  *
  39  * POST_RATE_CHANGE - called after the clk rate change has successfully
  40  *     completed.  Callbacks must always return NOTIFY_DONE or NOTIFY_OK.
  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_prepare - prepare a clock source
  89  * @clk: clock source
  90  *
  91  * This prepares the clock source for use.
  92  *
  93  * Must not be called from within atomic context.
  94  */
  95 #ifdef CONFIG_HAVE_CLK_PREPARE
  96 int clk_prepare(struct clk *clk);
  97 #else
  98 static inline int clk_prepare(struct clk *clk)
  99 {
 100         might_sleep();
 101         return 0;
 102 }
 103 #endif
 104
 105 /**
 106  * clk_unprepare - undo preparation of a clock source
 107  * @clk: clock source
 108  *
 109  * This undoes a previously prepared clock.  The caller must balance
 110  * the number of prepare and unprepare calls.
 111  *
 112  * Must not be called from within atomic context.
 113  */
 114 #ifdef CONFIG_HAVE_CLK_PREPARE
 115 void clk_unprepare(struct clk *clk);
 116 #else
 117 static inline void clk_unprepare(struct clk *clk)
 118 {
 119         might_sleep();
 120 }
 121 #endif
 122
 123 #ifdef CONFIG_HAVE_CLK
 124 /**
 125  * clk_get - lookup and obtain a reference to a clock producer.
 126  * @dev: device for clock "consumer"
 127  * @id: clock consumer ID
 128  *
 129  * Returns a struct clk corresponding to the clock producer, or
 130  * valid IS_ERR() condition containing errno.  The implementation
 131  * uses @dev and @id to determine the clock consumer, and thereby
 132  * the clock producer.  (IOW, @id may be identical strings, but
 133  * clk_get may return different clock producers depending on @dev.)
 134  *
 135  * Drivers must assume that the clock source is not enabled.
 136  *
 137  * clk_get should not be called from within interrupt context.
 138  */
 139 struct clk *clk_get(struct device *dev, const char *id);
 140
 141 /**
 142  * devm_clk_get - lookup and obtain a managed reference to a clock producer.
 143  * @dev: device for clock "consumer"
 144  * @id: clock consumer ID
 145  *
 146  * Returns a struct clk corresponding to the clock producer, or
 147  * valid IS_ERR() condition containing errno.  The implementation
 148  * uses @dev and @id to determine the clock consumer, and thereby
 149  * the clock producer.  (IOW, @id may be identical strings, but
 150  * clk_get may return different clock producers depending on @dev.)
 151  *
 152  * Drivers must assume that the clock source is not enabled.
 153  *
 154  * devm_clk_get should not be called from within interrupt context.
 155  *
 156  * The clock will automatically be freed when the device is unbound
 157  * from the bus.
 158  */
 159 struct clk *devm_clk_get(struct device *dev, const char *id);
 160
 161 /**
 162  * clk_enable - inform the system when the clock source should be running.
 163  * @clk: clock source
 164  *
 165  * If the clock can not be enabled/disabled, this should return success.
 166  *
 167  * May be called from atomic contexts.
 168  *
 169  * Returns success (0) or negative errno.
 170  */
 171 int clk_enable(struct clk *clk);
 172
 173 /**
 174  * clk_disable - inform the system when the clock source is no longer required.
 175  * @clk: clock source
 176  *
 177  * Inform the system that a clock source is no longer required by
 178  * a driver and may be shut down.
 179  *
 180  * May be called from atomic contexts.
 181  *
 182  * Implementation detail: if the clock source is shared between
 183  * multiple drivers, clk_enable() calls must be balanced by the
 184  * same number of clk_disable() calls for the clock source to be
 185  * disabled.
 186  */
 187 void clk_disable(struct clk *clk);
 188
 189 /**
 190  * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
 191  *                This is only valid once the clock source has been enabled.
 192  * @clk: clock source
 193  */
 194 unsigned long clk_get_rate(struct clk *clk);
 195
 196 /**
 197  * clk_put      - "free" the clock source
 198  * @clk: clock source
 199  *
 200  * Note: drivers must ensure that all clk_enable calls made on this
 201  * clock source are balanced by clk_disable calls prior to calling
 202  * this function.
 203  *
 204  * clk_put should not be called from within interrupt context.
 205  */
 206 void clk_put(struct clk *clk);
 207
 208 /**
 209  * devm_clk_put - "free" a managed clock source
 210  * @dev: device used to acuqire the clock
 211  * @clk: clock source acquired with devm_clk_get()
 212  *
 213  * Note: drivers must ensure that all clk_enable calls made on this
 214  * clock source are balanced by clk_disable calls prior to calling
 215  * this function.
 216  *
 217  * clk_put should not be called from within interrupt context.
 218  */
 219 void devm_clk_put(struct device *dev, struct clk *clk);
 220
 221 /*
 222  * The remaining APIs are optional for machine class support.
 223  */
 224
 225
 226 /**
 227  * clk_round_rate - adjust a rate to the exact rate a clock can provide
 228  * @clk: clock source
 229  * @rate: desired clock rate in Hz
 230  *
 231  * Returns rounded clock rate in Hz, or negative errno.
 232  */
 233 long clk_round_rate(struct clk *clk, unsigned long rate);
 234
 235 /**
 236  * clk_set_rate - set the clock rate for a clock source
 237  * @clk: clock source
 238  * @rate: desired clock rate in Hz
 239  *
 240  * Returns success (0) or negative errno.
 241  */
 242 int clk_set_rate(struct clk *clk, unsigned long rate);
 243
 244 /**
 245  * clk_set_parent - set the parent clock source for this clock
 246  * @clk: clock source
 247  * @parent: parent clock source
 248  *
 249  * Returns success (0) or negative errno.
 250  */
 251 int clk_set_parent(struct clk *clk, struct clk *parent);
 252
 253 /**
 254  * clk_get_parent - get the parent clock source for this clock
 255  * @clk: clock source
 256  *
 257  * Returns struct clk corresponding to parent clock source, or
 258  * valid IS_ERR() condition containing errno.
 259  */
 260 struct clk *clk_get_parent(struct clk *clk);
 261
 262 /**
 263  * clk_get_sys - get a clock based upon the device name
 264  * @dev_id: device name
 265  * @con_id: connection ID
 266  *
 267  * Returns a struct clk corresponding to the clock producer, or
 268  * valid IS_ERR() condition containing errno.  The implementation
 269  * uses @dev_id and @con_id to determine the clock consumer, and
 270  * thereby the clock producer. In contrast to clk_get() this function
 271  * takes the device name instead of the device itself for identification.
 272  *
 273  * Drivers must assume that the clock source is not enabled.
 274  *
 275  * clk_get_sys should not be called from within interrupt context.
 276  */
 277 struct clk *clk_get_sys(const char *dev_id, const char *con_id);
 278
 279 #else /* !CONFIG_HAVE_CLK */
 280
 281 static inline struct clk *clk_get(struct device *dev, const char *id)
 282 {
 283         return NULL;
 284 }
 285
 286 static inline struct clk *devm_clk_get(struct device *dev, const char *id)
 287 {
 288         return NULL;
 289 }
 290
 291 static inline void clk_put(struct clk *clk) {}
 292
 293 static inline void devm_clk_put(struct device *dev, struct clk *clk) {}
 294
 295 static inline int clk_enable(struct clk *clk)
 296 {
 297         return 0;
 298 }
 299
 300 static inline void clk_disable(struct clk *clk) {}
 301
 302 static inline unsigned long clk_get_rate(struct clk *clk)
 303 {
 304         return 0;
 305 }
 306
 307 static inline int clk_set_rate(struct clk *clk, unsigned long rate)
 308 {
 309         return 0;
 310 }
 311
 312 static inline long clk_round_rate(struct clk *clk, unsigned long rate)
 313 {
 314         return 0;
 315 }
 316
 317 static inline int clk_set_parent(struct clk *clk, struct clk *parent)
 318 {
 319         return 0;
 320 }
 321
 322 static inline struct clk *clk_get_parent(struct clk *clk)
 323 {
 324         return NULL;
 325 }
 326
 327 #endif
 328
 329 /* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
 330 static inline int clk_prepare_enable(struct clk *clk)
 331 {
 332         int ret;
 333
 334         ret = clk_prepare(clk);
 335         if (ret)
 336                 return ret;
 337         ret = clk_enable(clk);
 338         if (ret)
 339                 clk_unprepare(clk);
 340
 341         return ret;
 342 }
 343
 344 /* clk_disable_unprepare helps cases using clk_disable in non-atomic context. */
 345 static inline void clk_disable_unprepare(struct clk *clk)
 346 {
 347         clk_disable(clk);
 348         clk_unprepare(clk);
 349 }
 350
 351 /**
 352  * clk_add_alias - add a new clock alias
 353  * @alias: name for clock alias
 354  * @alias_dev_name: device name
 355  * @id: platform specific clock name
 356  * @dev: device
 357  *
 358  * Allows using generic clock names for drivers by adding a new alias.
 359  * Assumes clkdev, see clkdev.h for more info.
 360  */
 361 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 362                         struct device *dev);
 363
 364 struct device_node;
 365 struct of_phandle_args;
 366
 367 #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
 368 struct clk *of_clk_get(struct device_node *np, int index);
 369 struct clk *of_clk_get_by_name(struct device_node *np, const char *name);
 370 struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec);
 371 #else
 372 static inline struct clk *of_clk_get(struct device_node *np, int index)
 373 {
 374         return ERR_PTR(-ENOENT);
 375 }
 376 static inline struct clk *of_clk_get_by_name(struct device_node *np,
 377                                              const char *name)
 378 {
 379         return ERR_PTR(-ENOENT);
 380 }
 381 #endif
 382
 383 #endif