2 * linux/include/linux/clk.h
4 * Copyright (C) 2004 ARM Limited.
5 * Written by Deep Blue Solutions Limited.
6 * Copyright (C) 2011-2012 Linaro Ltd <mturquette@linaro.org>
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.
15 #include <linux/err.h>
16 #include <linux/kernel.h>
17 #include <linux/notifier.h>
23 #ifdef CONFIG_COMMON_CLK
26 * DOC: clk notifier callback types
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.
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.
39 * POST_RATE_CHANGE - called after the clk rate change has successfully
40 * completed. Callbacks must always return NOTIFY_DONE or NOTIFY_OK.
43 #define PRE_RATE_CHANGE BIT(0)
44 #define POST_RATE_CHANGE BIT(1)
45 #define ABORT_RATE_CHANGE BIT(2)
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
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
60 struct srcu_notifier_head notifier_head
;
61 struct list_head node
;
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
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).
75 struct clk_notifier_data
{
77 unsigned long old_rate
;
78 unsigned long new_rate
;
81 int clk_notifier_register(struct clk
*clk
, struct notifier_block
*nb
);
83 int clk_notifier_unregister(struct clk
*clk
, struct notifier_block
*nb
);
88 * clk_prepare - prepare a clock source
91 * This prepares the clock source for use.
93 * Must not be called from within atomic context.
95 #ifdef CONFIG_HAVE_CLK_PREPARE
96 int clk_prepare(struct clk
*clk
);
98 static inline int clk_prepare(struct clk
*clk
)
106 * clk_unprepare - undo preparation of a clock source
109 * This undoes a previously prepared clock. The caller must balance
110 * the number of prepare and unprepare calls.
112 * Must not be called from within atomic context.
114 #ifdef CONFIG_HAVE_CLK_PREPARE
115 void clk_unprepare(struct clk
*clk
);
117 static inline void clk_unprepare(struct clk
*clk
)
123 #ifdef CONFIG_HAVE_CLK
125 * clk_get - lookup and obtain a reference to a clock producer.
126 * @dev: device for clock "consumer"
127 * @id: clock consumer ID
129 * Returns a struct clk corresponding to the clock producer, or
130 * valid IS_ERR() condition containing errno. The implementation
131 * uses @dev and @id to determine the clock consumer, and thereby
132 * the clock producer. (IOW, @id may be identical strings, but
133 * clk_get may return different clock producers depending on @dev.)
135 * Drivers must assume that the clock source is not enabled.
137 * clk_get should not be called from within interrupt context.
139 struct clk
*clk_get(struct device
*dev
, const char *id
);
142 * devm_clk_get - lookup and obtain a managed reference to a clock producer.
143 * @dev: device for clock "consumer"
144 * @id: clock consumer ID
146 * Returns a struct clk corresponding to the clock producer, or
147 * valid IS_ERR() condition containing errno. The implementation
148 * uses @dev and @id to determine the clock consumer, and thereby
149 * the clock producer. (IOW, @id may be identical strings, but
150 * clk_get may return different clock producers depending on @dev.)
152 * Drivers must assume that the clock source is not enabled.
154 * devm_clk_get should not be called from within interrupt context.
156 * The clock will automatically be freed when the device is unbound
159 struct clk
*devm_clk_get(struct device
*dev
, const char *id
);
162 * clk_enable - inform the system when the clock source should be running.
165 * If the clock can not be enabled/disabled, this should return success.
167 * May be called from atomic contexts.
169 * Returns success (0) or negative errno.
171 int clk_enable(struct clk
*clk
);
174 * clk_disable - inform the system when the clock source is no longer required.
177 * Inform the system that a clock source is no longer required by
178 * a driver and may be shut down.
180 * May be called from atomic contexts.
182 * Implementation detail: if the clock source is shared between
183 * multiple drivers, clk_enable() calls must be balanced by the
184 * same number of clk_disable() calls for the clock source to be
187 void clk_disable(struct clk
*clk
);
190 * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
191 * This is only valid once the clock source has been enabled.
194 unsigned long clk_get_rate(struct clk
*clk
);
197 * clk_put - "free" the clock source
200 * Note: drivers must ensure that all clk_enable calls made on this
201 * clock source are balanced by clk_disable calls prior to calling
204 * clk_put should not be called from within interrupt context.
206 void clk_put(struct clk
*clk
);
209 * devm_clk_put - "free" a managed clock source
210 * @dev: device used to acuqire the clock
211 * @clk: clock source acquired with devm_clk_get()
213 * Note: drivers must ensure that all clk_enable calls made on this
214 * clock source are balanced by clk_disable calls prior to calling
217 * clk_put should not be called from within interrupt context.
219 void devm_clk_put(struct device
*dev
, struct clk
*clk
);
222 * The remaining APIs are optional for machine class support.
227 * clk_round_rate - adjust a rate to the exact rate a clock can provide
229 * @rate: desired clock rate in Hz
231 * Returns rounded clock rate in Hz, or negative errno.
233 long clk_round_rate(struct clk
*clk
, unsigned long rate
);
236 * clk_set_rate - set the clock rate for a clock source
238 * @rate: desired clock rate in Hz
240 * Returns success (0) or negative errno.
242 int clk_set_rate(struct clk
*clk
, unsigned long rate
);
245 * clk_set_parent - set the parent clock source for this clock
247 * @parent: parent clock source
249 * Returns success (0) or negative errno.
251 int clk_set_parent(struct clk
*clk
, struct clk
*parent
);
254 * clk_get_parent - get the parent clock source for this clock
257 * Returns struct clk corresponding to parent clock source, or
258 * valid IS_ERR() condition containing errno.
260 struct clk
*clk_get_parent(struct clk
*clk
);
263 * clk_get_sys - get a clock based upon the device name
264 * @dev_id: device name
265 * @con_id: connection ID
267 * Returns a struct clk corresponding to the clock producer, or
268 * valid IS_ERR() condition containing errno. The implementation
269 * uses @dev_id and @con_id to determine the clock consumer, and
270 * thereby the clock producer. In contrast to clk_get() this function
271 * takes the device name instead of the device itself for identification.
273 * Drivers must assume that the clock source is not enabled.
275 * clk_get_sys should not be called from within interrupt context.
277 struct clk
*clk_get_sys(const char *dev_id
, const char *con_id
);
279 #else /* !CONFIG_HAVE_CLK */
281 static inline struct clk
*clk_get(struct device
*dev
, const char *id
)
286 static inline struct clk
*devm_clk_get(struct device
*dev
, const char *id
)
291 static inline void clk_put(struct clk
*clk
) {}
293 static inline void devm_clk_put(struct device
*dev
, struct clk
*clk
) {}
295 static inline int clk_enable(struct clk
*clk
)
300 static inline void clk_disable(struct clk
*clk
) {}
302 static inline unsigned long clk_get_rate(struct clk
*clk
)
307 static inline int clk_set_rate(struct clk
*clk
, unsigned long rate
)
312 static inline long clk_round_rate(struct clk
*clk
, unsigned long rate
)
317 static inline int clk_set_parent(struct clk
*clk
, struct clk
*parent
)
322 static inline struct clk
*clk_get_parent(struct clk
*clk
)
329 /* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
330 static inline int clk_prepare_enable(struct clk
*clk
)
334 ret
= clk_prepare(clk
);
337 ret
= clk_enable(clk
);
344 /* clk_disable_unprepare helps cases using clk_disable in non-atomic context. */
345 static inline void clk_disable_unprepare(struct clk
*clk
)
352 * clk_add_alias - add a new clock alias
353 * @alias: name for clock alias
354 * @alias_dev_name: device name
355 * @id: platform specific clock name
358 * Allows using generic clock names for drivers by adding a new alias.
359 * Assumes clkdev, see clkdev.h for more info.
361 int clk_add_alias(const char *alias
, const char *alias_dev_name
, char *id
,
365 struct of_phandle_args
;
367 #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
368 struct clk
*of_clk_get(struct device_node
*np
, int index
);
369 struct clk
*of_clk_get_by_name(struct device_node
*np
, const char *name
);
370 struct clk
*of_clk_get_from_provider(struct of_phandle_args
*clkspec
);
372 static inline struct clk
*of_clk_get(struct device_node
*np
, int index
)
374 return ERR_PTR(-ENOENT
);
376 static inline struct clk
*of_clk_get_by_name(struct device_node
*np
,
379 return ERR_PTR(-ENOENT
);