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 /**
 110  * clk_set_phase - adjust the phase shift of a clock signal
 111  * @clk: clock signal source
 112  * @degrees: number of degrees the signal is shifted
 113  *
 114  * Shifts the phase of a clock signal by the specified degrees. Returns 0 on
 115  * success, -EERROR otherwise.
 116  */
 117 int clk_set_phase(struct clk *clk, int degrees);
 118
 119 /**
 120  * clk_get_phase - return the phase shift of a clock signal
 121  * @clk: clock signal source
 122  *
 123  * Returns the phase shift of a clock node in degrees, otherwise returns
 124  * -EERROR.
 125  */
 126 int clk_get_phase(struct clk *clk);
 127
 128 #else
 129
 130 static inline long clk_get_accuracy(struct clk *clk)
 131 {
 132         return -ENOTSUPP;
 133 }
 134
 135 static inline long clk_set_phase(struct clk *clk, int phase)
 136 {
 137         return -ENOTSUPP;
 138 }
 139
 140 static inline long clk_get_phase(struct clk *clk)
 141 {
 142         return -ENOTSUPP;
 143 }
 144
 145 #endif
 146
 147 /**
 148  * clk_prepare - prepare a clock source
 149  * @clk: clock source
 150  *
 151  * This prepares the clock source for use.
 152  *
 153  * Must not be called from within atomic context.
 154  */
 155 #ifdef CONFIG_HAVE_CLK_PREPARE
 156 int clk_prepare(struct clk *clk);
 157 #else
 158 static inline int clk_prepare(struct clk *clk)
 159 {
 160         might_sleep();
 161         return 0;
 162 }
 163 #endif
 164
 165 /**
 166  * clk_unprepare - undo preparation of a clock source
 167  * @clk: clock source
 168  *
 169  * This undoes a previously prepared clock.  The caller must balance
 170  * the number of prepare and unprepare calls.
 171  *
 172  * Must not be called from within atomic context.
 173  */
 174 #ifdef CONFIG_HAVE_CLK_PREPARE
 175 void clk_unprepare(struct clk *clk);
 176 #else
 177 static inline void clk_unprepare(struct clk *clk)
 178 {
 179         might_sleep();
 180 }
 181 #endif
 182
 183 #ifdef CONFIG_HAVE_CLK
 184 /**
 185  * clk_get - lookup and obtain a reference to a clock producer.
 186  * @dev: device for clock "consumer"
 187  * @id: clock consumer ID
 188  *
 189  * Returns a struct clk corresponding to the clock producer, or
 190  * valid IS_ERR() condition containing errno.  The implementation
 191  * uses @dev and @id to determine the clock consumer, and thereby
 192  * the clock producer.  (IOW, @id may be identical strings, but
 193  * clk_get may return different clock producers depending on @dev.)
 194  *
 195  * Drivers must assume that the clock source is not enabled.
 196  *
 197  * clk_get should not be called from within interrupt context.
 198  */
 199 struct clk *clk_get(struct device *dev, const char *id);
 200
 201 /**
 202  * devm_clk_get - lookup and obtain a managed reference to a clock producer.
 203  * @dev: device for clock "consumer"
 204  * @id: clock consumer ID
 205  *
 206  * Returns a struct clk corresponding to the clock producer, or
 207  * valid IS_ERR() condition containing errno.  The implementation
 208  * uses @dev and @id to determine the clock consumer, and thereby
 209  * the clock producer.  (IOW, @id may be identical strings, but
 210  * clk_get may return different clock producers depending on @dev.)
 211  *
 212  * Drivers must assume that the clock source is not enabled.
 213  *
 214  * devm_clk_get should not be called from within interrupt context.
 215  *
 216  * The clock will automatically be freed when the device is unbound
 217  * from the bus.
 218  */
 219 struct clk *devm_clk_get(struct device *dev, const char *id);
 220
 221 /**
 222  * clk_enable - inform the system when the clock source should be running.
 223  * @clk: clock source
 224  *
 225  * If the clock can not be enabled/disabled, this should return success.
 226  *
 227  * May be called from atomic contexts.
 228  *
 229  * Returns success (0) or negative errno.
 230  */
 231 int clk_enable(struct clk *clk);
 232
 233 /**
 234  * clk_disable - inform the system when the clock source is no longer required.
 235  * @clk: clock source
 236  *
 237  * Inform the system that a clock source is no longer required by
 238  * a driver and may be shut down.
 239  *
 240  * May be called from atomic contexts.
 241  *
 242  * Implementation detail: if the clock source is shared between
 243  * multiple drivers, clk_enable() calls must be balanced by the
 244  * same number of clk_disable() calls for the clock source to be
 245  * disabled.
 246  */
 247 void clk_disable(struct clk *clk);
 248
 249 /**
 250  * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
 251  *                This is only valid once the clock source has been enabled.
 252  * @clk: clock source
 253  */
 254 unsigned long clk_get_rate(struct clk *clk);
 255
 256 /**
 257  * clk_put      - "free" the clock source
 258  * @clk: clock source
 259  *
 260  * Note: drivers must ensure that all clk_enable calls made on this
 261  * clock source are balanced by clk_disable calls prior to calling
 262  * this function.
 263  *
 264  * clk_put should not be called from within interrupt context.
 265  */
 266 void clk_put(struct clk *clk);
 267
 268 /**
 269  * devm_clk_put - "free" a managed clock source
 270  * @dev: device used to acquire the clock
 271  * @clk: clock source acquired with devm_clk_get()
 272  *
 273  * Note: drivers must ensure that all clk_enable calls made on this
 274  * clock source are balanced by clk_disable calls prior to calling
 275  * this function.
 276  *
 277  * clk_put should not be called from within interrupt context.
 278  */
 279 void devm_clk_put(struct device *dev, struct clk *clk);
 280
 281 /*
 282  * The remaining APIs are optional for machine class support.
 283  */
 284
 285
 286 /**
 287  * clk_round_rate - adjust a rate to the exact rate a clock can provide
 288  * @clk: clock source
 289  * @rate: desired clock rate in Hz
 290  *
 291  * Returns rounded clock rate in Hz, or negative errno.
 292  */
 293 long clk_round_rate(struct clk *clk, unsigned long rate);
 294
 295 /**
 296  * clk_set_rate - set the clock rate for a clock source
 297  * @clk: clock source
 298  * @rate: desired clock rate in Hz
 299  *
 300  * Returns success (0) or negative errno.
 301  */
 302 int clk_set_rate(struct clk *clk, unsigned long rate);
 303
 304 /**
 305  * clk_set_parent - set the parent clock source for this clock
 306  * @clk: clock source
 307  * @parent: parent clock source
 308  *
 309  * Returns success (0) or negative errno.
 310  */
 311 int clk_set_parent(struct clk *clk, struct clk *parent);
 312
 313 /**
 314  * clk_get_parent - get the parent clock source for this clock
 315  * @clk: clock source
 316  *
 317  * Returns struct clk corresponding to parent clock source, or
 318  * valid IS_ERR() condition containing errno.
 319  */
 320 struct clk *clk_get_parent(struct clk *clk);
 321
 322 /**
 323  * clk_get_sys - get a clock based upon the device name
 324  * @dev_id: device name
 325  * @con_id: connection ID
 326  *
 327  * Returns a struct clk corresponding to the clock producer, or
 328  * valid IS_ERR() condition containing errno.  The implementation
 329  * uses @dev_id and @con_id to determine the clock consumer, and
 330  * thereby the clock producer. In contrast to clk_get() this function
 331  * takes the device name instead of the device itself for identification.
 332  *
 333  * Drivers must assume that the clock source is not enabled.
 334  *
 335  * clk_get_sys should not be called from within interrupt context.
 336  */
 337 struct clk *clk_get_sys(const char *dev_id, const char *con_id);
 338
 339 #else /* !CONFIG_HAVE_CLK */
 340
 341 static inline struct clk *clk_get(struct device *dev, const char *id)
 342 {
 343         return NULL;
 344 }
 345
 346 static inline struct clk *devm_clk_get(struct device *dev, const char *id)
 347 {
 348         return NULL;
 349 }
 350
 351 static inline void clk_put(struct clk *clk) {}
 352
 353 static inline void devm_clk_put(struct device *dev, struct clk *clk) {}
 354
 355 static inline int clk_enable(struct clk *clk)
 356 {
 357         return 0;
 358 }
 359
 360 static inline void clk_disable(struct clk *clk) {}
 361
 362 static inline unsigned long clk_get_rate(struct clk *clk)
 363 {
 364         return 0;
 365 }
 366
 367 static inline int clk_set_rate(struct clk *clk, unsigned long rate)
 368 {
 369         return 0;
 370 }
 371
 372 static inline long clk_round_rate(struct clk *clk, unsigned long rate)
 373 {
 374         return 0;
 375 }
 376
 377 static inline int clk_set_parent(struct clk *clk, struct clk *parent)
 378 {
 379         return 0;
 380 }
 381
 382 static inline struct clk *clk_get_parent(struct clk *clk)
 383 {
 384         return NULL;
 385 }
 386
 387 #endif
 388
 389 /* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
 390 static inline int clk_prepare_enable(struct clk *clk)
 391 {
 392         int ret;
 393
 394         ret = clk_prepare(clk);
 395         if (ret)
 396                 return ret;
 397         ret = clk_enable(clk);
 398         if (ret)
 399                 clk_unprepare(clk);
 400
 401         return ret;
 402 }
 403
 404 /* clk_disable_unprepare helps cases using clk_disable in non-atomic context. */
 405 static inline void clk_disable_unprepare(struct clk *clk)
 406 {
 407         clk_disable(clk);
 408         clk_unprepare(clk);
 409 }
 410
 411 /**
 412  * clk_add_alias - add a new clock alias
 413  * @alias: name for clock alias
 414  * @alias_dev_name: device name
 415  * @id: platform specific clock name
 416  * @dev: device
 417  *
 418  * Allows using generic clock names for drivers by adding a new alias.
 419  * Assumes clkdev, see clkdev.h for more info.
 420  */
 421 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 422                         struct device *dev);
 423
 424 struct device_node;
 425 struct of_phandle_args;
 426
 427 #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
 428 struct clk *of_clk_get(struct device_node *np, int index);
 429 struct clk *of_clk_get_by_name(struct device_node *np, const char *name);
 430 struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec);
 431 #else
 432 static inline struct clk *of_clk_get(struct device_node *np, int index)
 433 {
 434         return ERR_PTR(-ENOENT);
 435 }
 436 static inline struct clk *of_clk_get_by_name(struct device_node *np,
 437                                              const char *name)
 438 {
 439         return ERR_PTR(-ENOENT);
 440 }
 441 #endif
 442
 443 #endif