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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 
 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
444 

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