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 /**
  82  * clk_notifier_register: register a clock rate-change notifier callback
  83  * @clk: clock whose rate we are interested in
  84  * @nb: notifier block with callback function pointer
  85  *
  86  * ProTip: debugging across notifier chains can be frustrating. Make sure that
  87  * your notifier callback function prints a nice big warning in case of
  88  * failure.
  89  */
  90 int clk_notifier_register(struct clk *clk, struct notifier_block *nb);
  91
  92 /**
  93  * clk_notifier_unregister: unregister a clock rate-change notifier callback
  94  * @clk: clock whose rate we are no longer interested in
  95  * @nb: notifier block which will be unregistered
  96  */
  97 int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb);
  98
  99 /**
 100  * clk_get_accuracy - obtain the clock accuracy in ppb (parts per billion)
 101  *                    for a clock source.
 102  * @clk: clock source
 103  *
 104  * This gets the clock source accuracy expressed in ppb.
 105  * A perfect clock returns 0.
 106  */
 107 long clk_get_accuracy(struct clk *clk);
 108
 109 #else
 110
 111 static inline long clk_get_accuracy(struct clk *clk)
 112 {
 113         return -ENOTSUPP;
 114 }
 115
 116 #endif
 117
 118 /**
 119  * clk_prepare - prepare a clock source
 120  * @clk: clock source
 121  *
 122  * This prepares the clock source for use.
 123  *
 124  * Must not be called from within atomic context.
 125  */
 126 #ifdef CONFIG_HAVE_CLK_PREPARE
 127 int clk_prepare(struct clk *clk);
 128 #else
 129 static inline int clk_prepare(struct clk *clk)
 130 {
 131         might_sleep();
 132         return 0;
 133 }
 134 #endif
 135
 136 /**
 137  * clk_unprepare - undo preparation of a clock source
 138  * @clk: clock source
 139  *
 140  * This undoes a previously prepared clock.  The caller must balance
 141  * the number of prepare and unprepare calls.
 142  *
 143  * Must not be called from within atomic context.
 144  */
 145 #ifdef CONFIG_HAVE_CLK_PREPARE
 146 void clk_unprepare(struct clk *clk);
 147 #else
 148 static inline void clk_unprepare(struct clk *clk)
 149 {
 150         might_sleep();
 151 }
 152 #endif
 153
 154 #ifdef CONFIG_HAVE_CLK
 155 /**
 156  * clk_get - lookup and obtain a reference to a clock producer.
 157  * @dev: device for clock "consumer"
 158  * @id: clock consumer ID
 159  *
 160  * Returns a struct clk corresponding to the clock producer, or
 161  * valid IS_ERR() condition containing errno.  The implementation
 162  * uses @dev and @id to determine the clock consumer, and thereby
 163  * the clock producer.  (IOW, @id may be identical strings, but
 164  * clk_get may return different clock producers depending on @dev.)
 165  *
 166  * Drivers must assume that the clock source is not enabled.
 167  *
 168  * clk_get should not be called from within interrupt context.
 169  */
 170 struct clk *clk_get(struct device *dev, const char *id);
 171
 172 /**
 173  * devm_clk_get - lookup and obtain a managed reference to a clock producer.
 174  * @dev: device for clock "consumer"
 175  * @id: clock consumer ID
 176  *
 177  * Returns a struct clk corresponding to the clock producer, or
 178  * valid IS_ERR() condition containing errno.  The implementation
 179  * uses @dev and @id to determine the clock consumer, and thereby
 180  * the clock producer.  (IOW, @id may be identical strings, but
 181  * clk_get may return different clock producers depending on @dev.)
 182  *
 183  * Drivers must assume that the clock source is not enabled.
 184  *
 185  * devm_clk_get should not be called from within interrupt context.
 186  *
 187  * The clock will automatically be freed when the device is unbound
 188  * from the bus.
 189  */
 190 struct clk *devm_clk_get(struct device *dev, const char *id);
 191
 192 /**
 193  * clk_enable - inform the system when the clock source should be running.
 194  * @clk: clock source
 195  *
 196  * If the clock can not be enabled/disabled, this should return success.
 197  *
 198  * May be called from atomic contexts.
 199  *
 200  * Returns success (0) or negative errno.
 201  */
 202 int clk_enable(struct clk *clk);
 203
 204 /**
 205  * clk_disable - inform the system when the clock source is no longer required.
 206  * @clk: clock source
 207  *
 208  * Inform the system that a clock source is no longer required by
 209  * a driver and may be shut down.
 210  *
 211  * May be called from atomic contexts.
 212  *
 213  * Implementation detail: if the clock source is shared between
 214  * multiple drivers, clk_enable() calls must be balanced by the
 215  * same number of clk_disable() calls for the clock source to be
 216  * disabled.
 217  */
 218 void clk_disable(struct clk *clk);
 219
 220 /**
 221  * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
 222  *                This is only valid once the clock source has been enabled.
 223  * @clk: clock source
 224  */
 225 unsigned long clk_get_rate(struct clk *clk);
 226
 227 /**
 228  * clk_put      - "free" the clock source
 229  * @clk: clock source
 230  *
 231  * Note: drivers must ensure that all clk_enable calls made on this
 232  * clock source are balanced by clk_disable calls prior to calling
 233  * this function.
 234  *
 235  * clk_put should not be called from within interrupt context.
 236  */
 237 void clk_put(struct clk *clk);
 238
 239 /**
 240  * devm_clk_put - "free" a managed clock source
 241  * @dev: device used to acquire the clock
 242  * @clk: clock source acquired with devm_clk_get()
 243  *
 244  * Note: drivers must ensure that all clk_enable calls made on this
 245  * clock source are balanced by clk_disable calls prior to calling
 246  * this function.
 247  *
 248  * clk_put should not be called from within interrupt context.
 249  */
 250 void devm_clk_put(struct device *dev, struct clk *clk);
 251
 252 /*
 253  * The remaining APIs are optional for machine class support.
 254  */
 255
 256
 257 /**
 258  * clk_round_rate - adjust a rate to the exact rate a clock can provide
 259  * @clk: clock source
 260  * @rate: desired clock rate in Hz
 261  *
 262  * Returns rounded clock rate in Hz, or negative errno.
 263  */
 264 long clk_round_rate(struct clk *clk, unsigned long rate);
 265
 266 /**
 267  * clk_set_rate - set the clock rate for a clock source
 268  * @clk: clock source
 269  * @rate: desired clock rate in Hz
 270  *
 271  * Returns success (0) or negative errno.
 272  */
 273 int clk_set_rate(struct clk *clk, unsigned long rate);
 274
 275 /**
 276  * clk_set_parent - set the parent clock source for this clock
 277  * @clk: clock source
 278  * @parent: parent clock source
 279  *
 280  * Returns success (0) or negative errno.
 281  */
 282 int clk_set_parent(struct clk *clk, struct clk *parent);
 283
 284 /**
 285  * clk_get_parent - get the parent clock source for this clock
 286  * @clk: clock source
 287  *
 288  * Returns struct clk corresponding to parent clock source, or
 289  * valid IS_ERR() condition containing errno.
 290  */
 291 struct clk *clk_get_parent(struct clk *clk);
 292
 293 /**
 294  * clk_get_sys - get a clock based upon the device name
 295  * @dev_id: device name
 296  * @con_id: connection ID
 297  *
 298  * Returns a struct clk corresponding to the clock producer, or
 299  * valid IS_ERR() condition containing errno.  The implementation
 300  * uses @dev_id and @con_id to determine the clock consumer, and
 301  * thereby the clock producer. In contrast to clk_get() this function
 302  * takes the device name instead of the device itself for identification.
 303  *
 304  * Drivers must assume that the clock source is not enabled.
 305  *
 306  * clk_get_sys should not be called from within interrupt context.
 307  */
 308 struct clk *clk_get_sys(const char *dev_id, const char *con_id);
 309
 310 #else /* !CONFIG_HAVE_CLK */
 311
 312 static inline struct clk *clk_get(struct device *dev, const char *id)
 313 {
 314         return NULL;
 315 }
 316
 317 static inline struct clk *devm_clk_get(struct device *dev, const char *id)
 318 {
 319         return NULL;
 320 }
 321
 322 static inline void clk_put(struct clk *clk) {}
 323
 324 static inline void devm_clk_put(struct device *dev, struct clk *clk) {}
 325
 326 static inline int clk_enable(struct clk *clk)
 327 {
 328         return 0;
 329 }
 330
 331 static inline void clk_disable(struct clk *clk) {}
 332
 333 static inline unsigned long clk_get_rate(struct clk *clk)
 334 {
 335         return 0;
 336 }
 337
 338 static inline int clk_set_rate(struct clk *clk, unsigned long rate)
 339 {
 340         return 0;
 341 }
 342
 343 static inline long clk_round_rate(struct clk *clk, unsigned long rate)
 344 {
 345         return 0;
 346 }
 347
 348 static inline int clk_set_parent(struct clk *clk, struct clk *parent)
 349 {
 350         return 0;
 351 }
 352
 353 static inline struct clk *clk_get_parent(struct clk *clk)
 354 {
 355         return NULL;
 356 }
 357
 358 #endif
 359
 360 /* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
 361 static inline int clk_prepare_enable(struct clk *clk)
 362 {
 363         int ret;
 364
 365         ret = clk_prepare(clk);
 366         if (ret)
 367                 return ret;
 368         ret = clk_enable(clk);
 369         if (ret)
 370                 clk_unprepare(clk);
 371
 372         return ret;
 373 }
 374
 375 /* clk_disable_unprepare helps cases using clk_disable in non-atomic context. */
 376 static inline void clk_disable_unprepare(struct clk *clk)
 377 {
 378         clk_disable(clk);
 379         clk_unprepare(clk);
 380 }
 381
 382 /**
 383  * clk_add_alias - add a new clock alias
 384  * @alias: name for clock alias
 385  * @alias_dev_name: device name
 386  * @id: platform specific clock name
 387  * @dev: device
 388  *
 389  * Allows using generic clock names for drivers by adding a new alias.
 390  * Assumes clkdev, see clkdev.h for more info.
 391  */
 392 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 393                         struct device *dev);
 394
 395 struct device_node;
 396 struct of_phandle_args;
 397
 398 #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
 399 struct clk *of_clk_get(struct device_node *np, int index);
 400 struct clk *of_clk_get_by_name(struct device_node *np, const char *name);
 401 struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec);
 402 #else
 403 static inline struct clk *of_clk_get(struct device_node *np, int index)
 404 {
 405         return ERR_PTR(-ENOENT);
 406 }
 407 static inline struct clk *of_clk_get_by_name(struct device_node *np,
 408                                              const char *name)
 409 {
 410         return ERR_PTR(-ENOENT);
 411 }
 412 #endif
 413
 414 #endif