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 struct clk;
  21 struct device_node;
  22 struct of_phandle_args;
  23
  24 /**
  25  * DOC: clk notifier callback types
  26  *
  27  * PRE_RATE_CHANGE - called immediately before the clk rate is changed,
  28  *     to indicate that the rate change will proceed.  Drivers must
  29  *     immediately terminate any operations that will be affected by the
  30  *     rate change.  Callbacks may either return NOTIFY_DONE, NOTIFY_OK,
  31  *     NOTIFY_STOP or NOTIFY_BAD.
  32  *
  33  * ABORT_RATE_CHANGE: called if the rate change failed for some reason
  34  *     after PRE_RATE_CHANGE.  In this case, all registered notifiers on
  35  *     the clk will be called with ABORT_RATE_CHANGE. Callbacks must
  36  *     always return NOTIFY_DONE or NOTIFY_OK.
  37  *
  38  * POST_RATE_CHANGE - called after the clk rate change has successfully
  39  *     completed.  Callbacks must always return NOTIFY_DONE or NOTIFY_OK.
  40  *
  41  */
  42 #define PRE_RATE_CHANGE                 BIT(0)
  43 #define POST_RATE_CHANGE                BIT(1)
  44 #define ABORT_RATE_CHANGE               BIT(2)
  45
  46 /**
  47  * struct clk_notifier - associate a clk with a notifier
  48  * @clk: struct clk * to associate the notifier with
  49  * @notifier_head: a blocking_notifier_head for this clk
  50  * @node: linked list pointers
  51  *
  52  * A list of struct clk_notifier is maintained by the notifier code.
  53  * An entry is created whenever code registers the first notifier on a
  54  * particular @clk.  Future notifiers on that @clk are added to the
  55  * @notifier_head.
  56  */
  57 struct clk_notifier {
  58         struct clk                      *clk;
  59         struct srcu_notifier_head       notifier_head;
  60         struct list_head                node;
  61 };
  62
  63 /**
  64  * struct clk_notifier_data - rate data to pass to the notifier callback
  65  * @clk: struct clk * being changed
  66  * @old_rate: previous rate of this clk
  67  * @new_rate: new rate of this clk
  68  *
  69  * For a pre-notifier, old_rate is the clk's rate before this rate
  70  * change, and new_rate is what the rate will be in the future.  For a
  71  * post-notifier, old_rate and new_rate are both set to the clk's
  72  * current rate (this was done to optimize the implementation).
  73  */
  74 struct clk_notifier_data {
  75         struct clk              *clk;
  76         unsigned long           old_rate;
  77         unsigned long           new_rate;
  78 };
  79
  80 /**
  81  * struct clk_bulk_data - Data used for bulk clk operations.
  82  *
  83  * @id: clock consumer ID
  84  * @clk: struct clk * to store the associated clock
  85  *
  86  * The CLK APIs provide a series of clk_bulk_() API calls as
  87  * a convenience to consumers which require multiple clks.  This
  88  * structure is used to manage data for these calls.
  89  */
  90 struct clk_bulk_data {
  91         const char              *id;
  92         struct clk              *clk;
  93 };
  94
  95 #ifdef CONFIG_COMMON_CLK
  96
  97 /**
  98  * clk_notifier_register: register a clock rate-change notifier callback
  99  * @clk: clock whose rate we are interested in
 100  * @nb: notifier block with callback function pointer
 101  *
 102  * ProTip: debugging across notifier chains can be frustrating. Make sure that
 103  * your notifier callback function prints a nice big warning in case of
 104  * failure.
 105  */
 106 int clk_notifier_register(struct clk *clk, struct notifier_block *nb);
 107
 108 /**
 109  * clk_notifier_unregister: unregister a clock rate-change notifier callback
 110  * @clk: clock whose rate we are no longer interested in
 111  * @nb: notifier block which will be unregistered
 112  */
 113 int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb);
 114
 115 /**
 116  * clk_get_accuracy - obtain the clock accuracy in ppb (parts per billion)
 117  *                    for a clock source.
 118  * @clk: clock source
 119  *
 120  * This gets the clock source accuracy expressed in ppb.
 121  * A perfect clock returns 0.
 122  */
 123 long clk_get_accuracy(struct clk *clk);
 124
 125 /**
 126  * clk_set_phase - adjust the phase shift of a clock signal
 127  * @clk: clock signal source
 128  * @degrees: number of degrees the signal is shifted
 129  *
 130  * Shifts the phase of a clock signal by the specified degrees. Returns 0 on
 131  * success, -EERROR otherwise.
 132  */
 133 int clk_set_phase(struct clk *clk, int degrees);
 134
 135 /**
 136  * clk_get_phase - return the phase shift of a clock signal
 137  * @clk: clock signal source
 138  *
 139  * Returns the phase shift of a clock node in degrees, otherwise returns
 140  * -EERROR.
 141  */
 142 int clk_get_phase(struct clk *clk);
 143
 144 /**
 145  * clk_is_match - check if two clk's point to the same hardware clock
 146  * @p: clk compared against q
 147  * @q: clk compared against p
 148  *
 149  * Returns true if the two struct clk pointers both point to the same hardware
 150  * clock node. Put differently, returns true if @p and @q
 151  * share the same &struct clk_core object.
 152  *
 153  * Returns false otherwise. Note that two NULL clks are treated as matching.
 154  */
 155 bool clk_is_match(const struct clk *p, const struct clk *q);
 156
 157 #else
 158
 159 static inline int clk_notifier_register(struct clk *clk,
 160                                         struct notifier_block *nb)
 161 {
 162         return -ENOTSUPP;
 163 }
 164
 165 static inline int clk_notifier_unregister(struct clk *clk,
 166                                           struct notifier_block *nb)
 167 {
 168         return -ENOTSUPP;
 169 }
 170
 171 static inline long clk_get_accuracy(struct clk *clk)
 172 {
 173         return -ENOTSUPP;
 174 }
 175
 176 static inline long clk_set_phase(struct clk *clk, int phase)
 177 {
 178         return -ENOTSUPP;
 179 }
 180
 181 static inline long clk_get_phase(struct clk *clk)
 182 {
 183         return -ENOTSUPP;
 184 }
 185
 186 static inline bool clk_is_match(const struct clk *p, const struct clk *q)
 187 {
 188         return p == q;
 189 }
 190
 191 #endif
 192
 193 /**
 194  * clk_prepare - prepare a clock source
 195  * @clk: clock source
 196  *
 197  * This prepares the clock source for use.
 198  *
 199  * Must not be called from within atomic context.
 200  */
 201 #ifdef CONFIG_HAVE_CLK_PREPARE
 202 int clk_prepare(struct clk *clk);
 203 int __must_check clk_bulk_prepare(int num_clks,
 204                                   const struct clk_bulk_data *clks);
 205 #else
 206 static inline int clk_prepare(struct clk *clk)
 207 {
 208         might_sleep();
 209         return 0;
 210 }
 211
 212 static inline int clk_bulk_prepare(int num_clks, struct clk_bulk_data *clks)
 213 {
 214         might_sleep();
 215         return 0;
 216 }
 217 #endif
 218
 219 /**
 220  * clk_unprepare - undo preparation of a clock source
 221  * @clk: clock source
 222  *
 223  * This undoes a previously prepared clock.  The caller must balance
 224  * the number of prepare and unprepare calls.
 225  *
 226  * Must not be called from within atomic context.
 227  */
 228 #ifdef CONFIG_HAVE_CLK_PREPARE
 229 void clk_unprepare(struct clk *clk);
 230 void clk_bulk_unprepare(int num_clks, const struct clk_bulk_data *clks);
 231 #else
 232 static inline void clk_unprepare(struct clk *clk)
 233 {
 234         might_sleep();
 235 }
 236 static inline void clk_bulk_unprepare(int num_clks, struct clk_bulk_data *clks)
 237 {
 238         might_sleep();
 239 }
 240 #endif
 241
 242 #ifdef CONFIG_HAVE_CLK
 243 /**
 244  * clk_get - lookup and obtain a reference to a clock producer.
 245  * @dev: device for clock "consumer"
 246  * @id: clock consumer ID
 247  *
 248  * Returns a struct clk corresponding to the clock producer, or
 249  * valid IS_ERR() condition containing errno.  The implementation
 250  * uses @dev and @id to determine the clock consumer, and thereby
 251  * the clock producer.  (IOW, @id may be identical strings, but
 252  * clk_get may return different clock producers depending on @dev.)
 253  *
 254  * Drivers must assume that the clock source is not enabled.
 255  *
 256  * clk_get should not be called from within interrupt context.
 257  */
 258 struct clk *clk_get(struct device *dev, const char *id);
 259
 260 /**
 261  * clk_bulk_get - lookup and obtain a number of references to clock producer.
 262  * @dev: device for clock "consumer"
 263  * @num_clks: the number of clk_bulk_data
 264  * @clks: the clk_bulk_data table of consumer
 265  *
 266  * This helper function allows drivers to get several clk consumers in one
 267  * operation. If any of the clk cannot be acquired then any clks
 268  * that were obtained will be freed before returning to the caller.
 269  *
 270  * Returns 0 if all clocks specified in clk_bulk_data table are obtained
 271  * successfully, or valid IS_ERR() condition containing errno.
 272  * The implementation uses @dev and @clk_bulk_data.id to determine the
 273  * clock consumer, and thereby the clock producer.
 274  * The clock returned is stored in each @clk_bulk_data.clk field.
 275  *
 276  * Drivers must assume that the clock source is not enabled.
 277  *
 278  * clk_bulk_get should not be called from within interrupt context.
 279  */
 280 int __must_check clk_bulk_get(struct device *dev, int num_clks,
 281                               struct clk_bulk_data *clks);
 282
 283 /**
 284  * devm_clk_bulk_get - managed get multiple clk consumers
 285  * @dev: device for clock "consumer"
 286  * @num_clks: the number of clk_bulk_data
 287  * @clks: the clk_bulk_data table of consumer
 288  *
 289  * Return 0 on success, an errno on failure.
 290  *
 291  * This helper function allows drivers to get several clk
 292  * consumers in one operation with management, the clks will
 293  * automatically be freed when the device is unbound.
 294  */
 295 int __must_check devm_clk_bulk_get(struct device *dev, int num_clks,
 296                                    struct clk_bulk_data *clks);
 297
 298 /**
 299  * devm_clk_get - lookup and obtain a managed reference to a clock producer.
 300  * @dev: device for clock "consumer"
 301  * @id: clock consumer ID
 302  *
 303  * Returns a struct clk corresponding to the clock producer, or
 304  * valid IS_ERR() condition containing errno.  The implementation
 305  * uses @dev and @id to determine the clock consumer, and thereby
 306  * the clock producer.  (IOW, @id may be identical strings, but
 307  * clk_get may return different clock producers depending on @dev.)
 308  *
 309  * Drivers must assume that the clock source is not enabled.
 310  *
 311  * devm_clk_get should not be called from within interrupt context.
 312  *
 313  * The clock will automatically be freed when the device is unbound
 314  * from the bus.
 315  */
 316 struct clk *devm_clk_get(struct device *dev, const char *id);
 317
 318 /**
 319  * devm_get_clk_from_child - lookup and obtain a managed reference to a
 320  *                           clock producer from child node.
 321  * @dev: device for clock "consumer"
 322  * @np: pointer to clock consumer node
 323  * @con_id: clock consumer ID
 324  *
 325  * This function parses the clocks, and uses them to look up the
 326  * struct clk from the registered list of clock providers by using
 327  * @np and @con_id
 328  *
 329  * The clock will automatically be freed when the device is unbound
 330  * from the bus.
 331  */
 332 struct clk *devm_get_clk_from_child(struct device *dev,
 333                                     struct device_node *np, const char *con_id);
 334
 335 /**
 336  * clk_enable - inform the system when the clock source should be running.
 337  * @clk: clock source
 338  *
 339  * If the clock can not be enabled/disabled, this should return success.
 340  *
 341  * May be called from atomic contexts.
 342  *
 343  * Returns success (0) or negative errno.
 344  */
 345 int clk_enable(struct clk *clk);
 346
 347 /**
 348  * clk_bulk_enable - inform the system when the set of clks should be running.
 349  * @num_clks: the number of clk_bulk_data
 350  * @clks: the clk_bulk_data table of consumer
 351  *
 352  * May be called from atomic contexts.
 353  *
 354  * Returns success (0) or negative errno.
 355  */
 356 int __must_check clk_bulk_enable(int num_clks,
 357                                  const struct clk_bulk_data *clks);
 358
 359 /**
 360  * clk_disable - inform the system when the clock source is no longer required.
 361  * @clk: clock source
 362  *
 363  * Inform the system that a clock source is no longer required by
 364  * a driver and may be shut down.
 365  *
 366  * May be called from atomic contexts.
 367  *
 368  * Implementation detail: if the clock source is shared between
 369  * multiple drivers, clk_enable() calls must be balanced by the
 370  * same number of clk_disable() calls for the clock source to be
 371  * disabled.
 372  */
 373 void clk_disable(struct clk *clk);
 374
 375 /**
 376  * clk_bulk_disable - inform the system when the set of clks is no
 377  *                    longer required.
 378  * @num_clks: the number of clk_bulk_data
 379  * @clks: the clk_bulk_data table of consumer
 380  *
 381  * Inform the system that a set of clks is no longer required by
 382  * a driver and may be shut down.
 383  *
 384  * May be called from atomic contexts.
 385  *
 386  * Implementation detail: if the set of clks is shared between
 387  * multiple drivers, clk_bulk_enable() calls must be balanced by the
 388  * same number of clk_bulk_disable() calls for the clock source to be
 389  * disabled.
 390  */
 391 void clk_bulk_disable(int num_clks, const struct clk_bulk_data *clks);
 392
 393 /**
 394  * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
 395  *                This is only valid once the clock source has been enabled.
 396  * @clk: clock source
 397  */
 398 unsigned long clk_get_rate(struct clk *clk);
 399
 400 /**
 401  * clk_put      - "free" the clock source
 402  * @clk: clock source
 403  *
 404  * Note: drivers must ensure that all clk_enable calls made on this
 405  * clock source are balanced by clk_disable calls prior to calling
 406  * this function.
 407  *
 408  * clk_put should not be called from within interrupt context.
 409  */
 410 void clk_put(struct clk *clk);
 411
 412 /**
 413  * clk_bulk_put - "free" the clock source
 414  * @num_clks: the number of clk_bulk_data
 415  * @clks: the clk_bulk_data table of consumer
 416  *
 417  * Note: drivers must ensure that all clk_bulk_enable calls made on this
 418  * clock source are balanced by clk_bulk_disable calls prior to calling
 419  * this function.
 420  *
 421  * clk_bulk_put should not be called from within interrupt context.
 422  */
 423 void clk_bulk_put(int num_clks, struct clk_bulk_data *clks);
 424
 425 /**
 426  * devm_clk_put - "free" a managed clock source
 427  * @dev: device used to acquire the clock
 428  * @clk: clock source acquired with devm_clk_get()
 429  *
 430  * Note: drivers must ensure that all clk_enable calls made on this
 431  * clock source are balanced by clk_disable calls prior to calling
 432  * this function.
 433  *
 434  * clk_put should not be called from within interrupt context.
 435  */
 436 void devm_clk_put(struct device *dev, struct clk *clk);
 437
 438 /*
 439  * The remaining APIs are optional for machine class support.
 440  */
 441
 442
 443 /**
 444  * clk_round_rate - adjust a rate to the exact rate a clock can provide
 445  * @clk: clock source
 446  * @rate: desired clock rate in Hz
 447  *
 448  * This answers the question "if I were to pass @rate to clk_set_rate(),
 449  * what clock rate would I end up with?" without changing the hardware
 450  * in any way.  In other words:
 451  *
 452  *   rate = clk_round_rate(clk, r);
 453  *
 454  * and:
 455  *
 456  *   clk_set_rate(clk, r);
 457  *   rate = clk_get_rate(clk);
 458  *
 459  * are equivalent except the former does not modify the clock hardware
 460  * in any way.
 461  *
 462  * Returns rounded clock rate in Hz, or negative errno.
 463  */
 464 long clk_round_rate(struct clk *clk, unsigned long rate);
 465
 466 /**
 467  * clk_set_rate - set the clock rate for a clock source
 468  * @clk: clock source
 469  * @rate: desired clock rate in Hz
 470  *
 471  * Returns success (0) or negative errno.
 472  */
 473 int clk_set_rate(struct clk *clk, unsigned long rate);
 474
 475 /**
 476  * clk_has_parent - check if a clock is a possible parent for another
 477  * @clk: clock source
 478  * @parent: parent clock source
 479  *
 480  * This function can be used in drivers that need to check that a clock can be
 481  * the parent of another without actually changing the parent.
 482  *
 483  * Returns true if @parent is a possible parent for @clk, false otherwise.
 484  */
 485 bool clk_has_parent(struct clk *clk, struct clk *parent);
 486
 487 /**
 488  * clk_set_rate_range - set a rate range for a clock source
 489  * @clk: clock source
 490  * @min: desired minimum clock rate in Hz, inclusive
 491  * @max: desired maximum clock rate in Hz, inclusive
 492  *
 493  * Returns success (0) or negative errno.
 494  */
 495 int clk_set_rate_range(struct clk *clk, unsigned long min, unsigned long max);
 496
 497 /**
 498  * clk_set_min_rate - set a minimum clock rate for a clock source
 499  * @clk: clock source
 500  * @rate: desired minimum clock rate in Hz, inclusive
 501  *
 502  * Returns success (0) or negative errno.
 503  */
 504 int clk_set_min_rate(struct clk *clk, unsigned long rate);
 505
 506 /**
 507  * clk_set_max_rate - set a maximum clock rate for a clock source
 508  * @clk: clock source
 509  * @rate: desired maximum clock rate in Hz, inclusive
 510  *
 511  * Returns success (0) or negative errno.
 512  */
 513 int clk_set_max_rate(struct clk *clk, unsigned long rate);
 514
 515 /**
 516  * clk_set_parent - set the parent clock source for this clock
 517  * @clk: clock source
 518  * @parent: parent clock source
 519  *
 520  * Returns success (0) or negative errno.
 521  */
 522 int clk_set_parent(struct clk *clk, struct clk *parent);
 523
 524 /**
 525  * clk_get_parent - get the parent clock source for this clock
 526  * @clk: clock source
 527  *
 528  * Returns struct clk corresponding to parent clock source, or
 529  * valid IS_ERR() condition containing errno.
 530  */
 531 struct clk *clk_get_parent(struct clk *clk);
 532
 533 /**
 534  * clk_get_sys - get a clock based upon the device name
 535  * @dev_id: device name
 536  * @con_id: connection ID
 537  *
 538  * Returns a struct clk corresponding to the clock producer, or
 539  * valid IS_ERR() condition containing errno.  The implementation
 540  * uses @dev_id and @con_id to determine the clock consumer, and
 541  * thereby the clock producer. In contrast to clk_get() this function
 542  * takes the device name instead of the device itself for identification.
 543  *
 544  * Drivers must assume that the clock source is not enabled.
 545  *
 546  * clk_get_sys should not be called from within interrupt context.
 547  */
 548 struct clk *clk_get_sys(const char *dev_id, const char *con_id);
 549
 550 #else /* !CONFIG_HAVE_CLK */
 551
 552 static inline struct clk *clk_get(struct device *dev, const char *id)
 553 {
 554         return NULL;
 555 }
 556
 557 static inline int clk_bulk_get(struct device *dev, int num_clks,
 558                                struct clk_bulk_data *clks)
 559 {
 560         return 0;
 561 }
 562
 563 static inline struct clk *devm_clk_get(struct device *dev, const char *id)
 564 {
 565         return NULL;
 566 }
 567
 568 static inline int devm_clk_bulk_get(struct device *dev, int num_clks,
 569                                     struct clk_bulk_data *clks)
 570 {
 571         return 0;
 572 }
 573
 574 static inline struct clk *devm_get_clk_from_child(struct device *dev,
 575                                 struct device_node *np, const char *con_id)
 576 {
 577         return NULL;
 578 }
 579
 580 static inline void clk_put(struct clk *clk) {}
 581
 582 static inline void clk_bulk_put(int num_clks, struct clk_bulk_data *clks) {}
 583
 584 static inline void devm_clk_put(struct device *dev, struct clk *clk) {}
 585
 586 static inline int clk_enable(struct clk *clk)
 587 {
 588         return 0;
 589 }
 590
 591 static inline int clk_bulk_enable(int num_clks, struct clk_bulk_data *clks)
 592 {
 593         return 0;
 594 }
 595
 596 static inline void clk_disable(struct clk *clk) {}
 597
 598
 599 static inline void clk_bulk_disable(int num_clks,
 600                                     struct clk_bulk_data *clks) {}
 601
 602 static inline unsigned long clk_get_rate(struct clk *clk)
 603 {
 604         return 0;
 605 }
 606
 607 static inline int clk_set_rate(struct clk *clk, unsigned long rate)
 608 {
 609         return 0;
 610 }
 611
 612 static inline long clk_round_rate(struct clk *clk, unsigned long rate)
 613 {
 614         return 0;
 615 }
 616
 617 static inline bool clk_has_parent(struct clk *clk, struct clk *parent)
 618 {
 619         return true;
 620 }
 621
 622 static inline int clk_set_parent(struct clk *clk, struct clk *parent)
 623 {
 624         return 0;
 625 }
 626
 627 static inline struct clk *clk_get_parent(struct clk *clk)
 628 {
 629         return NULL;
 630 }
 631
 632 static inline struct clk *clk_get_sys(const char *dev_id, const char *con_id)
 633 {
 634         return NULL;
 635 }
 636 #endif
 637
 638 /* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
 639 static inline int clk_prepare_enable(struct clk *clk)
 640 {
 641         int ret;
 642
 643         ret = clk_prepare(clk);
 644         if (ret)
 645                 return ret;
 646         ret = clk_enable(clk);
 647         if (ret)
 648                 clk_unprepare(clk);
 649
 650         return ret;
 651 }
 652
 653 /* clk_disable_unprepare helps cases using clk_disable in non-atomic context. */
 654 static inline void clk_disable_unprepare(struct clk *clk)
 655 {
 656         clk_disable(clk);
 657         clk_unprepare(clk);
 658 }
 659
 660 static inline int clk_bulk_prepare_enable(int num_clks,
 661                                           struct clk_bulk_data *clks)
 662 {
 663         int ret;
 664
 665         ret = clk_bulk_prepare(num_clks, clks);
 666         if (ret)
 667                 return ret;
 668         ret = clk_bulk_enable(num_clks, clks);
 669         if (ret)
 670                 clk_bulk_unprepare(num_clks, clks);
 671
 672         return ret;
 673 }
 674
 675 static inline void clk_bulk_disable_unprepare(int num_clks,
 676                                               struct clk_bulk_data *clks)
 677 {
 678         clk_bulk_disable(num_clks, clks);
 679         clk_bulk_unprepare(num_clks, clks);
 680 }
 681
 682 #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
 683 struct clk *of_clk_get(struct device_node *np, int index);
 684 struct clk *of_clk_get_by_name(struct device_node *np, const char *name);
 685 struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec);
 686 #else
 687 static inline struct clk *of_clk_get(struct device_node *np, int index)
 688 {
 689         return ERR_PTR(-ENOENT);
 690 }
 691 static inline struct clk *of_clk_get_by_name(struct device_node *np,
 692                                              const char *name)
 693 {
 694         return ERR_PTR(-ENOENT);
 695 }
 696 static inline struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec)
 697 {
 698         return ERR_PTR(-ENOENT);
 699 }
 700 #endif
 701
 702 #endif