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 /**
  24  * DOC: clk notifier callback types
  25  *
  26  * PRE_RATE_CHANGE - called immediately before the clk rate is changed,
  27  *     to indicate that the rate change will proceed.  Drivers must
  28  *     immediately terminate any operations that will be affected by the
  29  *     rate change.  Callbacks may either return NOTIFY_DONE, NOTIFY_OK,
  30  *     NOTIFY_STOP or NOTIFY_BAD.
  31  *
  32  * ABORT_RATE_CHANGE: called if the rate change failed for some reason
  33  *     after PRE_RATE_CHANGE.  In this case, all registered notifiers on
  34  *     the clk will be called with ABORT_RATE_CHANGE. Callbacks must
  35  *     always return NOTIFY_DONE or NOTIFY_OK.
  36  *
  37  * POST_RATE_CHANGE - called after the clk rate change has successfully
  38  *     completed.  Callbacks must always return NOTIFY_DONE or NOTIFY_OK.
  39  *
  40  */
  41 #define PRE_RATE_CHANGE                 BIT(0)
  42 #define POST_RATE_CHANGE                BIT(1)
  43 #define ABORT_RATE_CHANGE               BIT(2)
  44
  45 /**
  46  * struct clk_notifier - associate a clk with a notifier
  47  * @clk: struct clk * to associate the notifier with
  48  * @notifier_head: a blocking_notifier_head for this clk
  49  * @node: linked list pointers
  50  *
  51  * A list of struct clk_notifier is maintained by the notifier code.
  52  * An entry is created whenever code registers the first notifier on a
  53  * particular @clk.  Future notifiers on that @clk are added to the
  54  * @notifier_head.
  55  */
  56 struct clk_notifier {
  57         struct clk                      *clk;
  58         struct srcu_notifier_head       notifier_head;
  59         struct list_head                node;
  60 };
  61
  62 /**
  63  * struct clk_notifier_data - rate data to pass to the notifier callback
  64  * @clk: struct clk * being changed
  65  * @old_rate: previous rate of this clk
  66  * @new_rate: new rate of this clk
  67  *
  68  * For a pre-notifier, old_rate is the clk's rate before this rate
  69  * change, and new_rate is what the rate will be in the future.  For a
  70  * post-notifier, old_rate and new_rate are both set to the clk's
  71  * current rate (this was done to optimize the implementation).
  72  */
  73 struct clk_notifier_data {
  74         struct clk              *clk;
  75         unsigned long           old_rate;
  76         unsigned long           new_rate;
  77 };
  78
  79 #ifdef CONFIG_COMMON_CLK
  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 /**
 129  * clk_is_match - check if two clk's point to the same hardware clock
 130  * @p: clk compared against q
 131  * @q: clk compared against p
 132  *
 133  * Returns true if the two struct clk pointers both point to the same hardware
 134  * clock node. Put differently, returns true if struct clk *p and struct clk *q
 135  * share the same struct clk_core object.
 136  *
 137  * Returns false otherwise. Note that two NULL clks are treated as matching.
 138  */
 139 bool clk_is_match(const struct clk *p, const struct clk *q);
 140
 141 #else
 142
 143 static inline int clk_notifier_register(struct clk *clk,
 144                                         struct notifier_block *nb)
 145 {
 146         return -ENOTSUPP;
 147 }
 148
 149 static inline int clk_notifier_unregister(struct clk *clk,
 150                                           struct notifier_block *nb)
 151 {
 152         return -ENOTSUPP;
 153 }
 154
 155 static inline long clk_get_accuracy(struct clk *clk)
 156 {
 157         return -ENOTSUPP;
 158 }
 159
 160 static inline long clk_set_phase(struct clk *clk, int phase)
 161 {
 162         return -ENOTSUPP;
 163 }
 164
 165 static inline long clk_get_phase(struct clk *clk)
 166 {
 167         return -ENOTSUPP;
 168 }
 169
 170 static inline bool clk_is_match(const struct clk *p, const struct clk *q)
 171 {
 172         return p == q;
 173 }
 174
 175 #endif
 176
 177 /**
 178  * clk_prepare - prepare a clock source
 179  * @clk: clock source
 180  *
 181  * This prepares the clock source for use.
 182  *
 183  * Must not be called from within atomic context.
 184  */
 185 #ifdef CONFIG_HAVE_CLK_PREPARE
 186 int clk_prepare(struct clk *clk);
 187 #else
 188 static inline int clk_prepare(struct clk *clk)
 189 {
 190         might_sleep();
 191         return 0;
 192 }
 193 #endif
 194
 195 /**
 196  * clk_unprepare - undo preparation of a clock source
 197  * @clk: clock source
 198  *
 199  * This undoes a previously prepared clock.  The caller must balance
 200  * the number of prepare and unprepare calls.
 201  *
 202  * Must not be called from within atomic context.
 203  */
 204 #ifdef CONFIG_HAVE_CLK_PREPARE
 205 void clk_unprepare(struct clk *clk);
 206 #else
 207 static inline void clk_unprepare(struct clk *clk)
 208 {
 209         might_sleep();
 210 }
 211 #endif
 212
 213 #ifdef CONFIG_HAVE_CLK
 214 /**
 215  * clk_get - lookup and obtain a reference to a clock producer.
 216  * @dev: device for clock "consumer"
 217  * @id: clock consumer ID
 218  *
 219  * Returns a struct clk corresponding to the clock producer, or
 220  * valid IS_ERR() condition containing errno.  The implementation
 221  * uses @dev and @id to determine the clock consumer, and thereby
 222  * the clock producer.  (IOW, @id may be identical strings, but
 223  * clk_get may return different clock producers depending on @dev.)
 224  *
 225  * Drivers must assume that the clock source is not enabled.
 226  *
 227  * clk_get should not be called from within interrupt context.
 228  */
 229 struct clk *clk_get(struct device *dev, const char *id);
 230
 231 /**
 232  * devm_clk_get - lookup and obtain a managed reference to a clock producer.
 233  * @dev: device for clock "consumer"
 234  * @id: clock consumer ID
 235  *
 236  * Returns a struct clk corresponding to the clock producer, or
 237  * valid IS_ERR() condition containing errno.  The implementation
 238  * uses @dev and @id to determine the clock consumer, and thereby
 239  * the clock producer.  (IOW, @id may be identical strings, but
 240  * clk_get may return different clock producers depending on @dev.)
 241  *
 242  * Drivers must assume that the clock source is not enabled.
 243  *
 244  * devm_clk_get should not be called from within interrupt context.
 245  *
 246  * The clock will automatically be freed when the device is unbound
 247  * from the bus.
 248  */
 249 struct clk *devm_clk_get(struct device *dev, const char *id);
 250
 251 /**
 252  * clk_enable - inform the system when the clock source should be running.
 253  * @clk: clock source
 254  *
 255  * If the clock can not be enabled/disabled, this should return success.
 256  *
 257  * May be called from atomic contexts.
 258  *
 259  * Returns success (0) or negative errno.
 260  */
 261 int clk_enable(struct clk *clk);
 262
 263 /**
 264  * clk_disable - inform the system when the clock source is no longer required.
 265  * @clk: clock source
 266  *
 267  * Inform the system that a clock source is no longer required by
 268  * a driver and may be shut down.
 269  *
 270  * May be called from atomic contexts.
 271  *
 272  * Implementation detail: if the clock source is shared between
 273  * multiple drivers, clk_enable() calls must be balanced by the
 274  * same number of clk_disable() calls for the clock source to be
 275  * disabled.
 276  */
 277 void clk_disable(struct clk *clk);
 278
 279 /**
 280  * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
 281  *                This is only valid once the clock source has been enabled.
 282  * @clk: clock source
 283  */
 284 unsigned long clk_get_rate(struct clk *clk);
 285
 286 /**
 287  * clk_put      - "free" the clock source
 288  * @clk: clock source
 289  *
 290  * Note: drivers must ensure that all clk_enable calls made on this
 291  * clock source are balanced by clk_disable calls prior to calling
 292  * this function.
 293  *
 294  * clk_put should not be called from within interrupt context.
 295  */
 296 void clk_put(struct clk *clk);
 297
 298 /**
 299  * devm_clk_put - "free" a managed clock source
 300  * @dev: device used to acquire the clock
 301  * @clk: clock source acquired with devm_clk_get()
 302  *
 303  * Note: drivers must ensure that all clk_enable calls made on this
 304  * clock source are balanced by clk_disable calls prior to calling
 305  * this function.
 306  *
 307  * clk_put should not be called from within interrupt context.
 308  */
 309 void devm_clk_put(struct device *dev, struct clk *clk);
 310
 311 /*
 312  * The remaining APIs are optional for machine class support.
 313  */
 314
 315
 316 /**
 317  * clk_round_rate - adjust a rate to the exact rate a clock can provide
 318  * @clk: clock source
 319  * @rate: desired clock rate in Hz
 320  *
 321  * This answers the question "if I were to pass @rate to clk_set_rate(),
 322  * what clock rate would I end up with?" without changing the hardware
 323  * in any way.  In other words:
 324  *
 325  *   rate = clk_round_rate(clk, r);
 326  *
 327  * and:
 328  *
 329  *   clk_set_rate(clk, r);
 330  *   rate = clk_get_rate(clk);
 331  *
 332  * are equivalent except the former does not modify the clock hardware
 333  * in any way.
 334  *
 335  * Returns rounded clock rate in Hz, or negative errno.
 336  */
 337 long clk_round_rate(struct clk *clk, unsigned long rate);
 338
 339 /**
 340  * clk_set_rate - set the clock rate for a clock source
 341  * @clk: clock source
 342  * @rate: desired clock rate in Hz
 343  *
 344  * Returns success (0) or negative errno.
 345  */
 346 int clk_set_rate(struct clk *clk, unsigned long rate);
 347
 348 /**
 349  * clk_has_parent - check if a clock is a possible parent for another
 350  * @clk: clock source
 351  * @parent: parent clock source
 352  *
 353  * This function can be used in drivers that need to check that a clock can be
 354  * the parent of another without actually changing the parent.
 355  *
 356  * Returns true if @parent is a possible parent for @clk, false otherwise.
 357  */
 358 bool clk_has_parent(struct clk *clk, struct clk *parent);
 359
 360 /**
 361  * clk_set_rate_range - set a rate range for a clock source
 362  * @clk: clock source
 363  * @min: desired minimum clock rate in Hz, inclusive
 364  * @max: desired maximum clock rate in Hz, inclusive
 365  *
 366  * Returns success (0) or negative errno.
 367  */
 368 int clk_set_rate_range(struct clk *clk, unsigned long min, unsigned long max);
 369
 370 /**
 371  * clk_set_min_rate - set a minimum clock rate for a clock source
 372  * @clk: clock source
 373  * @rate: desired minimum clock rate in Hz, inclusive
 374  *
 375  * Returns success (0) or negative errno.
 376  */
 377 int clk_set_min_rate(struct clk *clk, unsigned long rate);
 378
 379 /**
 380  * clk_set_max_rate - set a maximum clock rate for a clock source
 381  * @clk: clock source
 382  * @rate: desired maximum clock rate in Hz, inclusive
 383  *
 384  * Returns success (0) or negative errno.
 385  */
 386 int clk_set_max_rate(struct clk *clk, unsigned long rate);
 387
 388 /**
 389  * clk_set_parent - set the parent clock source for this clock
 390  * @clk: clock source
 391  * @parent: parent clock source
 392  *
 393  * Returns success (0) or negative errno.
 394  */
 395 int clk_set_parent(struct clk *clk, struct clk *parent);
 396
 397 /**
 398  * clk_get_parent - get the parent clock source for this clock
 399  * @clk: clock source
 400  *
 401  * Returns struct clk corresponding to parent clock source, or
 402  * valid IS_ERR() condition containing errno.
 403  */
 404 struct clk *clk_get_parent(struct clk *clk);
 405
 406 /**
 407  * clk_get_sys - get a clock based upon the device name
 408  * @dev_id: device name
 409  * @con_id: connection ID
 410  *
 411  * Returns a struct clk corresponding to the clock producer, or
 412  * valid IS_ERR() condition containing errno.  The implementation
 413  * uses @dev_id and @con_id to determine the clock consumer, and
 414  * thereby the clock producer. In contrast to clk_get() this function
 415  * takes the device name instead of the device itself for identification.
 416  *
 417  * Drivers must assume that the clock source is not enabled.
 418  *
 419  * clk_get_sys should not be called from within interrupt context.
 420  */
 421 struct clk *clk_get_sys(const char *dev_id, const char *con_id);
 422
 423 #else /* !CONFIG_HAVE_CLK */
 424
 425 static inline struct clk *clk_get(struct device *dev, const char *id)
 426 {
 427         return NULL;
 428 }
 429
 430 static inline struct clk *devm_clk_get(struct device *dev, const char *id)
 431 {
 432         return NULL;
 433 }
 434
 435 static inline void clk_put(struct clk *clk) {}
 436
 437 static inline void devm_clk_put(struct device *dev, struct clk *clk) {}
 438
 439 static inline int clk_enable(struct clk *clk)
 440 {
 441         return 0;
 442 }
 443
 444 static inline void clk_disable(struct clk *clk) {}
 445
 446 static inline unsigned long clk_get_rate(struct clk *clk)
 447 {
 448         return 0;
 449 }
 450
 451 static inline int clk_set_rate(struct clk *clk, unsigned long rate)
 452 {
 453         return 0;
 454 }
 455
 456 static inline long clk_round_rate(struct clk *clk, unsigned long rate)
 457 {
 458         return 0;
 459 }
 460
 461 static inline bool clk_has_parent(struct clk *clk, struct clk *parent)
 462 {
 463         return true;
 464 }
 465
 466 static inline int clk_set_parent(struct clk *clk, struct clk *parent)
 467 {
 468         return 0;
 469 }
 470
 471 static inline struct clk *clk_get_parent(struct clk *clk)
 472 {
 473         return NULL;
 474 }
 475
 476 static inline struct clk *clk_get_sys(const char *dev_id, const char *con_id)
 477 {
 478         return NULL;
 479 }
 480 #endif
 481
 482 /* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
 483 static inline int clk_prepare_enable(struct clk *clk)
 484 {
 485         int ret;
 486
 487         ret = clk_prepare(clk);
 488         if (ret)
 489                 return ret;
 490         ret = clk_enable(clk);
 491         if (ret)
 492                 clk_unprepare(clk);
 493
 494         return ret;
 495 }
 496
 497 /* clk_disable_unprepare helps cases using clk_disable in non-atomic context. */
 498 static inline void clk_disable_unprepare(struct clk *clk)
 499 {
 500         clk_disable(clk);
 501         clk_unprepare(clk);
 502 }
 503
 504 struct device_node;
 505 struct of_phandle_args;
 506
 507 #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
 508 struct clk *of_clk_get(struct device_node *np, int index);
 509 struct clk *of_clk_get_by_name(struct device_node *np, const char *name);
 510 struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec);
 511 #else
 512 static inline struct clk *of_clk_get(struct device_node *np, int index)
 513 {
 514         return ERR_PTR(-ENOENT);
 515 }
 516 static inline struct clk *of_clk_get_by_name(struct device_node *np,
 517                                              const char *name)
 518 {
 519         return ERR_PTR(-ENOENT);
 520 }
 521 #endif
 522
 523 #endif