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TOMOYO Linux Cross Reference
Linux/include/linux/clk.h

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  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 #ifdef CONFIG_COMMON_CLK
 81 
 82 /**
 83  * clk_notifier_register: register a clock rate-change notifier callback
 84  * @clk: clock whose rate we are interested in
 85  * @nb: notifier block with callback function pointer
 86  *
 87  * ProTip: debugging across notifier chains can be frustrating. Make sure that
 88  * your notifier callback function prints a nice big warning in case of
 89  * failure.
 90  */
 91 int clk_notifier_register(struct clk *clk, struct notifier_block *nb);
 92 
 93 /**
 94  * clk_notifier_unregister: unregister a clock rate-change notifier callback
 95  * @clk: clock whose rate we are no longer interested in
 96  * @nb: notifier block which will be unregistered
 97  */
 98 int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb);
 99 
100 /**
101  * clk_get_accuracy - obtain the clock accuracy in ppb (parts per billion)
102  *                    for a clock source.
103  * @clk: clock source
104  *
105  * This gets the clock source accuracy expressed in ppb.
106  * A perfect clock returns 0.
107  */
108 long clk_get_accuracy(struct clk *clk);
109 
110 /**
111  * clk_set_phase - adjust the phase shift of a clock signal
112  * @clk: clock signal source
113  * @degrees: number of degrees the signal is shifted
114  *
115  * Shifts the phase of a clock signal by the specified degrees. Returns 0 on
116  * success, -EERROR otherwise.
117  */
118 int clk_set_phase(struct clk *clk, int degrees);
119 
120 /**
121  * clk_get_phase - return the phase shift of a clock signal
122  * @clk: clock signal source
123  *
124  * Returns the phase shift of a clock node in degrees, otherwise returns
125  * -EERROR.
126  */
127 int clk_get_phase(struct clk *clk);
128 
129 /**
130  * clk_is_match - check if two clk's point to the same hardware clock
131  * @p: clk compared against q
132  * @q: clk compared against p
133  *
134  * Returns true if the two struct clk pointers both point to the same hardware
135  * clock node. Put differently, returns true if struct clk *p and struct clk *q
136  * share the same struct clk_core object.
137  *
138  * Returns false otherwise. Note that two NULL clks are treated as matching.
139  */
140 bool clk_is_match(const struct clk *p, const struct clk *q);
141 
142 #else
143 
144 static inline int clk_notifier_register(struct clk *clk,
145                                         struct notifier_block *nb)
146 {
147         return -ENOTSUPP;
148 }
149 
150 static inline int clk_notifier_unregister(struct clk *clk,
151                                           struct notifier_block *nb)
152 {
153         return -ENOTSUPP;
154 }
155 
156 static inline long clk_get_accuracy(struct clk *clk)
157 {
158         return -ENOTSUPP;
159 }
160 
161 static inline long clk_set_phase(struct clk *clk, int phase)
162 {
163         return -ENOTSUPP;
164 }
165 
166 static inline long clk_get_phase(struct clk *clk)
167 {
168         return -ENOTSUPP;
169 }
170 
171 static inline bool clk_is_match(const struct clk *p, const struct clk *q)
172 {
173         return p == q;
174 }
175 
176 #endif
177 
178 /**
179  * clk_prepare - prepare a clock source
180  * @clk: clock source
181  *
182  * This prepares the clock source for use.
183  *
184  * Must not be called from within atomic context.
185  */
186 #ifdef CONFIG_HAVE_CLK_PREPARE
187 int clk_prepare(struct clk *clk);
188 #else
189 static inline int clk_prepare(struct clk *clk)
190 {
191         might_sleep();
192         return 0;
193 }
194 #endif
195 
196 /**
197  * clk_unprepare - undo preparation of a clock source
198  * @clk: clock source
199  *
200  * This undoes a previously prepared clock.  The caller must balance
201  * the number of prepare and unprepare calls.
202  *
203  * Must not be called from within atomic context.
204  */
205 #ifdef CONFIG_HAVE_CLK_PREPARE
206 void clk_unprepare(struct clk *clk);
207 #else
208 static inline void clk_unprepare(struct clk *clk)
209 {
210         might_sleep();
211 }
212 #endif
213 
214 #ifdef CONFIG_HAVE_CLK
215 /**
216  * clk_get - lookup and obtain a reference to a clock producer.
217  * @dev: device for clock "consumer"
218  * @id: clock consumer ID
219  *
220  * Returns a struct clk corresponding to the clock producer, or
221  * valid IS_ERR() condition containing errno.  The implementation
222  * uses @dev and @id to determine the clock consumer, and thereby
223  * the clock producer.  (IOW, @id may be identical strings, but
224  * clk_get may return different clock producers depending on @dev.)
225  *
226  * Drivers must assume that the clock source is not enabled.
227  *
228  * clk_get should not be called from within interrupt context.
229  */
230 struct clk *clk_get(struct device *dev, const char *id);
231 
232 /**
233  * devm_clk_get - lookup and obtain a managed reference to a clock producer.
234  * @dev: device for clock "consumer"
235  * @id: clock consumer ID
236  *
237  * Returns a struct clk corresponding to the clock producer, or
238  * valid IS_ERR() condition containing errno.  The implementation
239  * uses @dev and @id to determine the clock consumer, and thereby
240  * the clock producer.  (IOW, @id may be identical strings, but
241  * clk_get may return different clock producers depending on @dev.)
242  *
243  * Drivers must assume that the clock source is not enabled.
244  *
245  * devm_clk_get should not be called from within interrupt context.
246  *
247  * The clock will automatically be freed when the device is unbound
248  * from the bus.
249  */
250 struct clk *devm_clk_get(struct device *dev, const char *id);
251 
252 /**
253  * devm_get_clk_from_child - lookup and obtain a managed reference to a
254  *                           clock producer from child node.
255  * @dev: device for clock "consumer"
256  * @np: pointer to clock consumer node
257  * @con_id: clock consumer ID
258  *
259  * This function parses the clocks, and uses them to look up the
260  * struct clk from the registered list of clock providers by using
261  * @np and @con_id
262  *
263  * The clock will automatically be freed when the device is unbound
264  * from the bus.
265  */
266 struct clk *devm_get_clk_from_child(struct device *dev,
267                                     struct device_node *np, const char *con_id);
268 
269 /**
270  * clk_enable - inform the system when the clock source should be running.
271  * @clk: clock source
272  *
273  * If the clock can not be enabled/disabled, this should return success.
274  *
275  * May be called from atomic contexts.
276  *
277  * Returns success (0) or negative errno.
278  */
279 int clk_enable(struct clk *clk);
280 
281 /**
282  * clk_disable - inform the system when the clock source is no longer required.
283  * @clk: clock source
284  *
285  * Inform the system that a clock source is no longer required by
286  * a driver and may be shut down.
287  *
288  * May be called from atomic contexts.
289  *
290  * Implementation detail: if the clock source is shared between
291  * multiple drivers, clk_enable() calls must be balanced by the
292  * same number of clk_disable() calls for the clock source to be
293  * disabled.
294  */
295 void clk_disable(struct clk *clk);
296 
297 /**
298  * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
299  *                This is only valid once the clock source has been enabled.
300  * @clk: clock source
301  */
302 unsigned long clk_get_rate(struct clk *clk);
303 
304 /**
305  * clk_put      - "free" the clock source
306  * @clk: clock source
307  *
308  * Note: drivers must ensure that all clk_enable calls made on this
309  * clock source are balanced by clk_disable calls prior to calling
310  * this function.
311  *
312  * clk_put should not be called from within interrupt context.
313  */
314 void clk_put(struct clk *clk);
315 
316 /**
317  * devm_clk_put - "free" a managed clock source
318  * @dev: device used to acquire the clock
319  * @clk: clock source acquired with devm_clk_get()
320  *
321  * Note: drivers must ensure that all clk_enable calls made on this
322  * clock source are balanced by clk_disable calls prior to calling
323  * this function.
324  *
325  * clk_put should not be called from within interrupt context.
326  */
327 void devm_clk_put(struct device *dev, struct clk *clk);
328 
329 /*
330  * The remaining APIs are optional for machine class support.
331  */
332 
333 
334 /**
335  * clk_round_rate - adjust a rate to the exact rate a clock can provide
336  * @clk: clock source
337  * @rate: desired clock rate in Hz
338  *
339  * This answers the question "if I were to pass @rate to clk_set_rate(),
340  * what clock rate would I end up with?" without changing the hardware
341  * in any way.  In other words:
342  *
343  *   rate = clk_round_rate(clk, r);
344  *
345  * and:
346  *
347  *   clk_set_rate(clk, r);
348  *   rate = clk_get_rate(clk);
349  *
350  * are equivalent except the former does not modify the clock hardware
351  * in any way.
352  *
353  * Returns rounded clock rate in Hz, or negative errno.
354  */
355 long clk_round_rate(struct clk *clk, unsigned long rate);
356 
357 /**
358  * clk_set_rate - set the clock rate for a clock source
359  * @clk: clock source
360  * @rate: desired clock rate in Hz
361  *
362  * Returns success (0) or negative errno.
363  */
364 int clk_set_rate(struct clk *clk, unsigned long rate);
365 
366 /**
367  * clk_has_parent - check if a clock is a possible parent for another
368  * @clk: clock source
369  * @parent: parent clock source
370  *
371  * This function can be used in drivers that need to check that a clock can be
372  * the parent of another without actually changing the parent.
373  *
374  * Returns true if @parent is a possible parent for @clk, false otherwise.
375  */
376 bool clk_has_parent(struct clk *clk, struct clk *parent);
377 
378 /**
379  * clk_set_rate_range - set a rate range for a clock source
380  * @clk: clock source
381  * @min: desired minimum clock rate in Hz, inclusive
382  * @max: desired maximum clock rate in Hz, inclusive
383  *
384  * Returns success (0) or negative errno.
385  */
386 int clk_set_rate_range(struct clk *clk, unsigned long min, unsigned long max);
387 
388 /**
389  * clk_set_min_rate - set a minimum clock rate for a clock source
390  * @clk: clock source
391  * @rate: desired minimum clock rate in Hz, inclusive
392  *
393  * Returns success (0) or negative errno.
394  */
395 int clk_set_min_rate(struct clk *clk, unsigned long rate);
396 
397 /**
398  * clk_set_max_rate - set a maximum clock rate for a clock source
399  * @clk: clock source
400  * @rate: desired maximum clock rate in Hz, inclusive
401  *
402  * Returns success (0) or negative errno.
403  */
404 int clk_set_max_rate(struct clk *clk, unsigned long rate);
405 
406 /**
407  * clk_set_parent - set the parent clock source for this clock
408  * @clk: clock source
409  * @parent: parent clock source
410  *
411  * Returns success (0) or negative errno.
412  */
413 int clk_set_parent(struct clk *clk, struct clk *parent);
414 
415 /**
416  * clk_get_parent - get the parent clock source for this clock
417  * @clk: clock source
418  *
419  * Returns struct clk corresponding to parent clock source, or
420  * valid IS_ERR() condition containing errno.
421  */
422 struct clk *clk_get_parent(struct clk *clk);
423 
424 /**
425  * clk_get_sys - get a clock based upon the device name
426  * @dev_id: device name
427  * @con_id: connection ID
428  *
429  * Returns a struct clk corresponding to the clock producer, or
430  * valid IS_ERR() condition containing errno.  The implementation
431  * uses @dev_id and @con_id to determine the clock consumer, and
432  * thereby the clock producer. In contrast to clk_get() this function
433  * takes the device name instead of the device itself for identification.
434  *
435  * Drivers must assume that the clock source is not enabled.
436  *
437  * clk_get_sys should not be called from within interrupt context.
438  */
439 struct clk *clk_get_sys(const char *dev_id, const char *con_id);
440 
441 #else /* !CONFIG_HAVE_CLK */
442 
443 static inline struct clk *clk_get(struct device *dev, const char *id)
444 {
445         return NULL;
446 }
447 
448 static inline struct clk *devm_clk_get(struct device *dev, const char *id)
449 {
450         return NULL;
451 }
452 
453 static inline struct clk *devm_get_clk_from_child(struct device *dev,
454                                 struct device_node *np, const char *con_id)
455 {
456         return NULL;
457 }
458 
459 static inline void clk_put(struct clk *clk) {}
460 
461 static inline void devm_clk_put(struct device *dev, struct clk *clk) {}
462 
463 static inline int clk_enable(struct clk *clk)
464 {
465         return 0;
466 }
467 
468 static inline void clk_disable(struct clk *clk) {}
469 
470 static inline unsigned long clk_get_rate(struct clk *clk)
471 {
472         return 0;
473 }
474 
475 static inline int clk_set_rate(struct clk *clk, unsigned long rate)
476 {
477         return 0;
478 }
479 
480 static inline long clk_round_rate(struct clk *clk, unsigned long rate)
481 {
482         return 0;
483 }
484 
485 static inline bool clk_has_parent(struct clk *clk, struct clk *parent)
486 {
487         return true;
488 }
489 
490 static inline int clk_set_parent(struct clk *clk, struct clk *parent)
491 {
492         return 0;
493 }
494 
495 static inline struct clk *clk_get_parent(struct clk *clk)
496 {
497         return NULL;
498 }
499 
500 static inline struct clk *clk_get_sys(const char *dev_id, const char *con_id)
501 {
502         return NULL;
503 }
504 #endif
505 
506 /* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
507 static inline int clk_prepare_enable(struct clk *clk)
508 {
509         int ret;
510 
511         ret = clk_prepare(clk);
512         if (ret)
513                 return ret;
514         ret = clk_enable(clk);
515         if (ret)
516                 clk_unprepare(clk);
517 
518         return ret;
519 }
520 
521 /* clk_disable_unprepare helps cases using clk_disable in non-atomic context. */
522 static inline void clk_disable_unprepare(struct clk *clk)
523 {
524         clk_disable(clk);
525         clk_unprepare(clk);
526 }
527 
528 #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
529 struct clk *of_clk_get(struct device_node *np, int index);
530 struct clk *of_clk_get_by_name(struct device_node *np, const char *name);
531 struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec);
532 #else
533 static inline struct clk *of_clk_get(struct device_node *np, int index)
534 {
535         return ERR_PTR(-ENOENT);
536 }
537 static inline struct clk *of_clk_get_by_name(struct device_node *np,
538                                              const char *name)
539 {
540         return ERR_PTR(-ENOENT);
541 }
542 #endif
543 
544 #endif
545 

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