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 or
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.
39 * POST_RATE_CHANGE - called after the clk rate change has successfully
40 * completed. Callbacks must always return NOTIFY_DONE.
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_get - lookup and obtain a reference to a clock producer.
89 * @dev: device for clock "consumer"
90 * @id: clock consumer ID
92 * Returns a struct clk corresponding to the clock producer, or
93 * valid IS_ERR() condition containing errno. The implementation
94 * uses @dev and @id to determine the clock consumer, and thereby
95 * the clock producer. (IOW, @id may be identical strings, but
96 * clk_get may return different clock producers depending on @dev.)
98 * Drivers must assume that the clock source is not enabled.
100 * clk_get should not be called from within interrupt context.
102 struct clk *clk_get(struct device *dev, const char *id);
105 * devm_clk_get - lookup and obtain a managed reference to a clock producer.
106 * @dev: device for clock "consumer"
107 * @id: clock consumer ID
109 * Returns a struct clk corresponding to the clock producer, or
110 * valid IS_ERR() condition containing errno. The implementation
111 * uses @dev and @id to determine the clock consumer, and thereby
112 * the clock producer. (IOW, @id may be identical strings, but
113 * clk_get may return different clock producers depending on @dev.)
115 * Drivers must assume that the clock source is not enabled.
117 * devm_clk_get should not be called from within interrupt context.
119 * The clock will automatically be freed when the device is unbound
122 struct clk *devm_clk_get(struct device *dev, const char *id);
125 * clk_prepare - prepare a clock source
128 * This prepares the clock source for use.
130 * Must not be called from within atomic context.
132 #ifdef CONFIG_HAVE_CLK_PREPARE
133 int clk_prepare(struct clk *clk);
135 static inline int clk_prepare(struct clk *clk)
143 * clk_enable - inform the system when the clock source should be running.
146 * If the clock can not be enabled/disabled, this should return success.
148 * May be called from atomic contexts.
150 * Returns success (0) or negative errno.
152 int clk_enable(struct clk *clk);
155 * clk_disable - inform the system when the clock source is no longer required.
158 * Inform the system that a clock source is no longer required by
159 * a driver and may be shut down.
161 * May be called from atomic contexts.
163 * Implementation detail: if the clock source is shared between
164 * multiple drivers, clk_enable() calls must be balanced by the
165 * same number of clk_disable() calls for the clock source to be
168 void clk_disable(struct clk *clk);
172 * clk_unprepare - undo preparation of a clock source
175 * This undoes a previously prepared clock. The caller must balance
176 * the number of prepare and unprepare calls.
178 * Must not be called from within atomic context.
180 #ifdef CONFIG_HAVE_CLK_PREPARE
181 void clk_unprepare(struct clk *clk);
183 static inline void clk_unprepare(struct clk *clk)
189 /* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
190 static inline int clk_prepare_enable(struct clk *clk)
194 ret = clk_prepare(clk);
197 ret = clk_enable(clk);
204 /* clk_disable_unprepare helps cases using clk_disable in non-atomic context. */
205 static inline void clk_disable_unprepare(struct clk *clk)
212 * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
213 * This is only valid once the clock source has been enabled.
216 unsigned long clk_get_rate(struct clk *clk);
219 * clk_put - "free" the clock source
222 * Note: drivers must ensure that all clk_enable calls made on this
223 * clock source are balanced by clk_disable calls prior to calling
226 * clk_put should not be called from within interrupt context.
228 void clk_put(struct clk *clk);
231 * devm_clk_put - "free" a managed clock source
232 * @dev: device used to acuqire the clock
233 * @clk: clock source acquired with devm_clk_get()
235 * Note: drivers must ensure that all clk_enable calls made on this
236 * clock source are balanced by clk_disable calls prior to calling
239 * clk_put should not be called from within interrupt context.
241 void devm_clk_put(struct device *dev, struct clk *clk);
244 * The remaining APIs are optional for machine class support.
249 * clk_round_rate - adjust a rate to the exact rate a clock can provide
251 * @rate: desired clock rate in Hz
253 * Returns rounded clock rate in Hz, or negative errno.
255 long clk_round_rate(struct clk *clk, unsigned long rate);
258 * clk_set_rate - set the clock rate for a clock source
260 * @rate: desired clock rate in Hz
262 * Returns success (0) or negative errno.
264 int clk_set_rate(struct clk *clk, unsigned long rate);
267 * clk_set_parent - set the parent clock source for this clock
269 * @parent: parent clock source
271 * Returns success (0) or negative errno.
273 int clk_set_parent(struct clk *clk, struct clk *parent);
276 * clk_get_parent - get the parent clock source for this clock
279 * Returns struct clk corresponding to parent clock source, or
280 * valid IS_ERR() condition containing errno.
282 struct clk *clk_get_parent(struct clk *clk);
285 * clk_get_sys - get a clock based upon the device name
286 * @dev_id: device name
287 * @con_id: connection ID
289 * Returns a struct clk corresponding to the clock producer, or
290 * valid IS_ERR() condition containing errno. The implementation
291 * uses @dev_id and @con_id to determine the clock consumer, and
292 * thereby the clock producer. In contrast to clk_get() this function
293 * takes the device name instead of the device itself for identification.
295 * Drivers must assume that the clock source is not enabled.
297 * clk_get_sys should not be called from within interrupt context.
299 struct clk *clk_get_sys(const char *dev_id, const char *con_id);
302 * clk_add_alias - add a new clock alias
303 * @alias: name for clock alias
304 * @alias_dev_name: device name
305 * @id: platform specific clock name
308 * Allows using generic clock names for drivers by adding a new alias.
309 * Assumes clkdev, see clkdev.h for more info.
311 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
315 struct of_phandle_args;
317 #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
318 struct clk *of_clk_get(struct device_node *np, int index);
319 struct clk *of_clk_get_by_name(struct device_node *np, const char *name);
320 struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec);
322 static inline struct clk *of_clk_get(struct device_node *np, int index)
324 return ERR_PTR(-ENOENT);
326 static inline struct clk *of_clk_get_by_name(struct device_node *np,
329 return ERR_PTR(-ENOENT);