xref: /linux-6.15/include/linux/clk.h (revision af89cd45)

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 *  linux/include/linux/clk.h
 *
 *  Copyright (C) 2004 ARM Limited.
 *  Written by Deep Blue Solutions Limited.
 *  Copyright (C) 2011-2012 Linaro Ltd <[email protected]>
 */
#ifndef __LINUX_CLK_H
#define __LINUX_CLK_H

#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/notifier.h>

struct device;
struct clk;
struct device_node;
struct of_phandle_args;

/**
 * DOC: clk notifier callback types
 *
 * PRE_RATE_CHANGE - called immediately before the clk rate is changed,
 *     to indicate that the rate change will proceed.  Drivers must
 *     immediately terminate any operations that will be affected by the
 *     rate change.  Callbacks may either return NOTIFY_DONE, NOTIFY_OK,
 *     NOTIFY_STOP or NOTIFY_BAD.
 *
 * ABORT_RATE_CHANGE: called if the rate change failed for some reason
 *     after PRE_RATE_CHANGE.  In this case, all registered notifiers on
 *     the clk will be called with ABORT_RATE_CHANGE. Callbacks must
 *     always return NOTIFY_DONE or NOTIFY_OK.
 *
 * POST_RATE_CHANGE - called after the clk rate change has successfully
 *     completed.  Callbacks must always return NOTIFY_DONE or NOTIFY_OK.
 *
 */
#define PRE_RATE_CHANGE			BIT(0)
#define POST_RATE_CHANGE		BIT(1)
#define ABORT_RATE_CHANGE		BIT(2)

/**
 * struct clk_notifier - associate a clk with a notifier
 * @clk: struct clk * to associate the notifier with
 * @notifier_head: a blocking_notifier_head for this clk
 * @node: linked list pointers
 *
 * A list of struct clk_notifier is maintained by the notifier code.
 * An entry is created whenever code registers the first notifier on a
 * particular @clk.  Future notifiers on that @clk are added to the
 * @notifier_head.
 */
struct clk_notifier {
	struct clk			*clk;
	struct srcu_notifier_head	notifier_head;
	struct list_head		node;
};

/**
 * struct clk_notifier_data - rate data to pass to the notifier callback
 * @clk: struct clk * being changed
 * @old_rate: previous rate of this clk
 * @new_rate: new rate of this clk
 *
 * For a pre-notifier, old_rate is the clk's rate before this rate
 * change, and new_rate is what the rate will be in the future.  For a
 * post-notifier, old_rate and new_rate are both set to the clk's
 * current rate (this was done to optimize the implementation).
 */
struct clk_notifier_data {
	struct clk		*clk;
	unsigned long		old_rate;
	unsigned long		new_rate;
};

/**
 * struct clk_bulk_data - Data used for bulk clk operations.
 *
 * @id: clock consumer ID
 * @clk: struct clk * to store the associated clock
 *
 * The CLK APIs provide a series of clk_bulk_() API calls as
 * a convenience to consumers which require multiple clks.  This
 * structure is used to manage data for these calls.
 */
struct clk_bulk_data {
	const char		*id;
	struct clk		*clk;
};

#ifdef CONFIG_COMMON_CLK

/**
 * clk_notifier_register - register a clock rate-change notifier callback
 * @clk: clock whose rate we are interested in
 * @nb: notifier block with callback function pointer
 *
 * ProTip: debugging across notifier chains can be frustrating. Make sure that
 * your notifier callback function prints a nice big warning in case of
 * failure.
 */
int clk_notifier_register(struct clk *clk, struct notifier_block *nb);

/**
 * clk_notifier_unregister - unregister a clock rate-change notifier callback
 * @clk: clock whose rate we are no longer interested in
 * @nb: notifier block which will be unregistered
 */
int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb);

/**
 * devm_clk_notifier_register - register a managed rate-change notifier callback
 * @dev: device for clock "consumer"
 * @clk: clock whose rate we are interested in
 * @nb: notifier block with callback function pointer
 *
 * Returns 0 on success, -EERROR otherwise
 */
int devm_clk_notifier_register(struct device *dev, struct clk *clk,
			       struct notifier_block *nb);

/**
 * clk_get_accuracy - obtain the clock accuracy in ppb (parts per billion)
 *		      for a clock source.
 * @clk: clock source
 *
 * This gets the clock source accuracy expressed in ppb.
 * A perfect clock returns 0.
 */
long clk_get_accuracy(struct clk *clk);

/**
 * clk_set_phase - adjust the phase shift of a clock signal
 * @clk: clock signal source
 * @degrees: number of degrees the signal is shifted
 *
 * Shifts the phase of a clock signal by the specified degrees. Returns 0 on
 * success, -EERROR otherwise.
 */
int clk_set_phase(struct clk *clk, int degrees);

/**
 * clk_get_phase - return the phase shift of a clock signal
 * @clk: clock signal source
 *
 * Returns the phase shift of a clock node in degrees, otherwise returns
 * -EERROR.
 */
int clk_get_phase(struct clk *clk);

/**
 * clk_set_duty_cycle - adjust the duty cycle ratio of a clock signal
 * @clk: clock signal source
 * @num: numerator of the duty cycle ratio to be applied
 * @den: denominator of the duty cycle ratio to be applied
 *
 * Adjust the duty cycle of a clock signal by the specified ratio. Returns 0 on
 * success, -EERROR otherwise.
 */
int clk_set_duty_cycle(struct clk *clk, unsigned int num, unsigned int den);

/**
 * clk_get_scaled_duty_cycle - return the duty cycle ratio of a clock signal
 * @clk: clock signal source
 * @scale: scaling factor to be applied to represent the ratio as an integer
 *
 * Returns the duty cycle ratio multiplied by the scale provided, otherwise
 * returns -EERROR.
 */
int clk_get_scaled_duty_cycle(struct clk *clk, unsigned int scale);

/**
 * clk_is_match - check if two clk's point to the same hardware clock
 * @p: clk compared against q
 * @q: clk compared against p
 *
 * Returns true if the two struct clk pointers both point to the same hardware
 * clock node. Put differently, returns true if @p and @q
 * share the same &struct clk_core object.
 *
 * Returns false otherwise. Note that two NULL clks are treated as matching.
 */
bool clk_is_match(const struct clk *p, const struct clk *q);

#else

static inline int clk_notifier_register(struct clk *clk,
					struct notifier_block *nb)
{
	return -ENOTSUPP;
}

static inline int clk_notifier_unregister(struct clk *clk,
					  struct notifier_block *nb)
{
	return -ENOTSUPP;
}

static inline int devm_clk_notifier_register(struct device *dev,
					     struct clk *clk,
					     struct notifier_block *nb)
{
	return -ENOTSUPP;
}

static inline long clk_get_accuracy(struct clk *clk)
{
	return -ENOTSUPP;
}

static inline long clk_set_phase(struct clk *clk, int phase)
{
	return -ENOTSUPP;
}

static inline long clk_get_phase(struct clk *clk)
{
	return -ENOTSUPP;
}

static inline int clk_set_duty_cycle(struct clk *clk, unsigned int num,
				     unsigned int den)
{
	return -ENOTSUPP;
}

static inline unsigned int clk_get_scaled_duty_cycle(struct clk *clk,
						     unsigned int scale)
{
	return 0;
}

static inline bool clk_is_match(const struct clk *p, const struct clk *q)
{
	return p == q;
}

#endif

#ifdef CONFIG_HAVE_CLK_PREPARE
/**
 * clk_prepare - prepare a clock source
 * @clk: clock source
 *
 * This prepares the clock source for use.
 *
 * Must not be called from within atomic context.
 */
int clk_prepare(struct clk *clk);
int __must_check clk_bulk_prepare(int num_clks,
				  const struct clk_bulk_data *clks);

/**
 * clk_is_enabled_when_prepared - indicate if preparing a clock also enables it.
 * @clk: clock source
 *
 * Returns true if clk_prepare() implicitly enables the clock, effectively
 * making clk_enable()/clk_disable() no-ops, false otherwise.
 *
 * This is of interest mainly to the power management code where actually
 * disabling the clock also requires unpreparing it to have any material
 * effect.
 *
 * Regardless of the value returned here, the caller must always invoke
 * clk_enable() or clk_prepare_enable()  and counterparts for usage counts
 * to be right.
 */
bool clk_is_enabled_when_prepared(struct clk *clk);
#else
static inline int clk_prepare(struct clk *clk)
{
	might_sleep();
	return 0;
}

static inline int __must_check
clk_bulk_prepare(int num_clks, const struct clk_bulk_data *clks)
{
	might_sleep();
	return 0;
}

static inline bool clk_is_enabled_when_prepared(struct clk *clk)
{
	return false;
}
#endif

/**
 * clk_unprepare - undo preparation of a clock source
 * @clk: clock source
 *
 * This undoes a previously prepared clock.  The caller must balance
 * the number of prepare and unprepare calls.
 *
 * Must not be called from within atomic context.
 */
#ifdef CONFIG_HAVE_CLK_PREPARE
void clk_unprepare(struct clk *clk);
void clk_bulk_unprepare(int num_clks, const struct clk_bulk_data *clks);
#else
static inline void clk_unprepare(struct clk *clk)
{
	might_sleep();
}
static inline void clk_bulk_unprepare(int num_clks,
				      const struct clk_bulk_data *clks)
{
	might_sleep();
}
#endif

#ifdef CONFIG_HAVE_CLK
/**
 * clk_get - lookup and obtain a reference to a clock producer.
 * @dev: device for clock "consumer"
 * @id: clock consumer ID
 *
 * Returns a struct clk corresponding to the clock producer, or
 * valid IS_ERR() condition containing errno.  The implementation
 * uses @dev and @id to determine the clock consumer, and thereby
 * the clock producer.  (IOW, @id may be identical strings, but
 * clk_get may return different clock producers depending on @dev.)
 *
 * Drivers must assume that the clock source is not enabled.
 *
 * clk_get should not be called from within interrupt context.
 */
struct clk *clk_get(struct device *dev, const char *id);

/**
 * clk_bulk_get - lookup and obtain a number of references to clock producer.
 * @dev: device for clock "consumer"
 * @num_clks: the number of clk_bulk_data
 * @clks: the clk_bulk_data table of consumer
 *
 * This helper function allows drivers to get several clk consumers in one
 * operation. If any of the clk cannot be acquired then any clks
 * that were obtained will be freed before returning to the caller.
 *
 * Returns 0 if all clocks specified in clk_bulk_data table are obtained
 * successfully, or valid IS_ERR() condition containing errno.
 * The implementation uses @dev and @clk_bulk_data.id to determine the
 * clock consumer, and thereby the clock producer.
 * The clock returned is stored in each @clk_bulk_data.clk field.
 *
 * Drivers must assume that the clock source is not enabled.
 *
 * clk_bulk_get should not be called from within interrupt context.
 */
int __must_check clk_bulk_get(struct device *dev, int num_clks,
			      struct clk_bulk_data *clks);
/**
 * clk_bulk_get_all - lookup and obtain all available references to clock
 *		      producer.
 * @dev: device for clock "consumer"
 * @clks: pointer to the clk_bulk_data table of consumer
 *
 * This helper function allows drivers to get all clk consumers in one
 * operation. If any of the clk cannot be acquired then any clks
 * that were obtained will be freed before returning to the caller.
 *
 * Returns a positive value for the number of clocks obtained while the
 * clock references are stored in the clk_bulk_data table in @clks field.
 * Returns 0 if there're none and a negative value if something failed.
 *
 * Drivers must assume that the clock source is not enabled.
 *
 * clk_bulk_get should not be called from within interrupt context.
 */
int __must_check clk_bulk_get_all(struct device *dev,
				  struct clk_bulk_data **clks);

/**
 * clk_bulk_get_optional - lookup and obtain a number of references to clock producer
 * @dev: device for clock "consumer"
 * @num_clks: the number of clk_bulk_data
 * @clks: the clk_bulk_data table of consumer
 *
 * Behaves the same as clk_bulk_get() except where there is no clock producer.
 * In this case, instead of returning -ENOENT, the function returns 0 and
 * NULL for a clk for which a clock producer could not be determined.
 */
int __must_check clk_bulk_get_optional(struct device *dev, int num_clks,
				       struct clk_bulk_data *clks);
/**
 * devm_clk_bulk_get - managed get multiple clk consumers
 * @dev: device for clock "consumer"
 * @num_clks: the number of clk_bulk_data
 * @clks: the clk_bulk_data table of consumer
 *
 * Return 0 on success, an errno on failure.
 *
 * This helper function allows drivers to get several clk
 * consumers in one operation with management, the clks will
 * automatically be freed when the device is unbound.
 */
int __must_check devm_clk_bulk_get(struct device *dev, int num_clks,
				   struct clk_bulk_data *clks);
/**
 * devm_clk_bulk_get_optional - managed get multiple optional consumer clocks
 * @dev: device for clock "consumer"
 * @num_clks: the number of clk_bulk_data
 * @clks: pointer to the clk_bulk_data table of consumer
 *
 * Behaves the same as devm_clk_bulk_get() except where there is no clock
 * producer.  In this case, instead of returning -ENOENT, the function returns
 * NULL for given clk. It is assumed all clocks in clk_bulk_data are optional.
 *
 * Returns 0 if all clocks specified in clk_bulk_data table are obtained
 * successfully or for any clk there was no clk provider available, otherwise
 * returns valid IS_ERR() condition containing errno.
 * The implementation uses @dev and @clk_bulk_data.id to determine the
 * clock consumer, and thereby the clock producer.
 * The clock returned is stored in each @clk_bulk_data.clk field.
 *
 * Drivers must assume that the clock source is not enabled.
 *
 * clk_bulk_get should not be called from within interrupt context.
 */
int __must_check devm_clk_bulk_get_optional(struct device *dev, int num_clks,
					    struct clk_bulk_data *clks);
/**
 * devm_clk_bulk_get_all - managed get multiple clk consumers
 * @dev: device for clock "consumer"
 * @clks: pointer to the clk_bulk_data table of consumer
 *
 * Returns a positive value for the number of clocks obtained while the
 * clock references are stored in the clk_bulk_data table in @clks field.
 * Returns 0 if there're none and a negative value if something failed.
 *
 * This helper function allows drivers to get several clk
 * consumers in one operation with management, the clks will
 * automatically be freed when the device is unbound.
 */

int __must_check devm_clk_bulk_get_all(struct device *dev,
				       struct clk_bulk_data **clks);

/**
 * devm_clk_get - lookup and obtain a managed reference to a clock producer.
 * @dev: device for clock "consumer"
 * @id: clock consumer ID
 *
 * Context: May sleep.
 *
 * Return: a struct clk corresponding to the clock producer, or
 * valid IS_ERR() condition containing errno.  The implementation
 * uses @dev and @id to determine the clock consumer, and thereby
 * the clock producer.  (IOW, @id may be identical strings, but
 * clk_get may return different clock producers depending on @dev.)
 *
 * Drivers must assume that the clock source is neither prepared nor
 * enabled.
 *
 * The clock will automatically be freed when the device is unbound
 * from the bus.
 */
struct clk *devm_clk_get(struct device *dev, const char *id);

/**
 * devm_clk_get_optional - lookup and obtain a managed reference to an optional
 *			   clock producer.
 * @dev: device for clock "consumer"
 * @id: clock consumer ID
 *
 * Context: May sleep.
 *
 * Return: a struct clk corresponding to the clock producer, or
 * valid IS_ERR() condition containing errno.  The implementation
 * uses @dev and @id to determine the clock consumer, and thereby
 * the clock producer.  If no such clk is found, it returns NULL
 * which serves as a dummy clk.  That's the only difference compared
 * to devm_clk_get().
 *
 * Drivers must assume that the clock source is neither prepared nor
 * enabled.
 *
 * The clock will automatically be freed when the device is unbound
 * from the bus.
 */
struct clk *devm_clk_get_optional(struct device *dev, const char *id);

/**
 * devm_get_clk_from_child - lookup and obtain a managed reference to a
 *			     clock producer from child node.
 * @dev: device for clock "consumer"
 * @np: pointer to clock consumer node
 * @con_id: clock consumer ID
 *
 * This function parses the clocks, and uses them to look up the
 * struct clk from the registered list of clock providers by using
 * @np and @con_id
 *
 * The clock will automatically be freed when the device is unbound
 * from the bus.
 */
struct clk *devm_get_clk_from_child(struct device *dev,
				    struct device_node *np, const char *con_id);
/**
 * clk_rate_exclusive_get - get exclusivity over the rate control of a
 *                          producer
 * @clk: clock source
 *
 * This function allows drivers to get exclusive control over the rate of a
 * provider. It prevents any other consumer to execute, even indirectly,
 * opereation which could alter the rate of the provider or cause glitches
 *
 * If exlusivity is claimed more than once on clock, even by the same driver,
 * the rate effectively gets locked as exclusivity can't be preempted.
 *
 * Must not be called from within atomic context.
 *
 * Returns success (0) or negative errno.
 */
int clk_rate_exclusive_get(struct clk *clk);

/**
 * clk_rate_exclusive_put - release exclusivity over the rate control of a
 *                          producer
 * @clk: clock source
 *
 * This function allows drivers to release the exclusivity it previously got
 * from clk_rate_exclusive_get()
 *
 * The caller must balance the number of clk_rate_exclusive_get() and
 * clk_rate_exclusive_put() calls.
 *
 * Must not be called from within atomic context.
 */
void clk_rate_exclusive_put(struct clk *clk);

/**
 * clk_enable - inform the system when the clock source should be running.
 * @clk: clock source
 *
 * If the clock can not be enabled/disabled, this should return success.
 *
 * May be called from atomic contexts.
 *
 * Returns success (0) or negative errno.
 */
int clk_enable(struct clk *clk);

/**
 * clk_bulk_enable - inform the system when the set of clks should be running.
 * @num_clks: the number of clk_bulk_data
 * @clks: the clk_bulk_data table of consumer
 *
 * May be called from atomic contexts.
 *
 * Returns success (0) or negative errno.
 */
int __must_check clk_bulk_enable(int num_clks,
				 const struct clk_bulk_data *clks);

/**
 * clk_disable - inform the system when the clock source is no longer required.
 * @clk: clock source
 *
 * Inform the system that a clock source is no longer required by
 * a driver and may be shut down.
 *
 * May be called from atomic contexts.
 *
 * Implementation detail: if the clock source is shared between
 * multiple drivers, clk_enable() calls must be balanced by the
 * same number of clk_disable() calls for the clock source to be
 * disabled.
 */
void clk_disable(struct clk *clk);

/**
 * clk_bulk_disable - inform the system when the set of clks is no
 *		      longer required.
 * @num_clks: the number of clk_bulk_data
 * @clks: the clk_bulk_data table of consumer
 *
 * Inform the system that a set of clks is no longer required by
 * a driver and may be shut down.
 *
 * May be called from atomic contexts.
 *
 * Implementation detail: if the set of clks is shared between
 * multiple drivers, clk_bulk_enable() calls must be balanced by the
 * same number of clk_bulk_disable() calls for the clock source to be
 * disabled.
 */
void clk_bulk_disable(int num_clks, const struct clk_bulk_data *clks);

/**
 * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
 *		  This is only valid once the clock source has been enabled.
 * @clk: clock source
 */
unsigned long clk_get_rate(struct clk *clk);

/**
 * clk_put	- "free" the clock source
 * @clk: clock source
 *
 * Note: drivers must ensure that all clk_enable calls made on this
 * clock source are balanced by clk_disable calls prior to calling
 * this function.
 *
 * clk_put should not be called from within interrupt context.
 */
void clk_put(struct clk *clk);

/**
 * clk_bulk_put	- "free" the clock source
 * @num_clks: the number of clk_bulk_data
 * @clks: the clk_bulk_data table of consumer
 *
 * Note: drivers must ensure that all clk_bulk_enable calls made on this
 * clock source are balanced by clk_bulk_disable calls prior to calling
 * this function.
 *
 * clk_bulk_put should not be called from within interrupt context.
 */
void clk_bulk_put(int num_clks, struct clk_bulk_data *clks);

/**
 * clk_bulk_put_all - "free" all the clock source
 * @num_clks: the number of clk_bulk_data
 * @clks: the clk_bulk_data table of consumer
 *
 * Note: drivers must ensure that all clk_bulk_enable calls made on this
 * clock source are balanced by clk_bulk_disable calls prior to calling
 * this function.
 *
 * clk_bulk_put_all should not be called from within interrupt context.
 */
void clk_bulk_put_all(int num_clks, struct clk_bulk_data *clks);

/**
 * devm_clk_put	- "free" a managed clock source
 * @dev: device used to acquire the clock
 * @clk: clock source acquired with devm_clk_get()
 *
 * Note: drivers must ensure that all clk_enable calls made on this
 * clock source are balanced by clk_disable calls prior to calling
 * this function.
 *
 * clk_put should not be called from within interrupt context.
 */
void devm_clk_put(struct device *dev, struct clk *clk);

/*
 * The remaining APIs are optional for machine class support.
 */


/**
 * clk_round_rate - adjust a rate to the exact rate a clock can provide
 * @clk: clock source
 * @rate: desired clock rate in Hz
 *
 * This answers the question "if I were to pass @rate to clk_set_rate(),
 * what clock rate would I end up with?" without changing the hardware
 * in any way.  In other words:
 *
 *   rate = clk_round_rate(clk, r);
 *
 * and:
 *
 *   clk_set_rate(clk, r);
 *   rate = clk_get_rate(clk);
 *
 * are equivalent except the former does not modify the clock hardware
 * in any way.
 *
 * Returns rounded clock rate in Hz, or negative errno.
 */
long clk_round_rate(struct clk *clk, unsigned long rate);

/**
 * clk_set_rate - set the clock rate for a clock source
 * @clk: clock source
 * @rate: desired clock rate in Hz
 *
 * Updating the rate starts at the top-most affected clock and then
 * walks the tree down to the bottom-most clock that needs updating.
 *
 * Returns success (0) or negative errno.
 */
int clk_set_rate(struct clk *clk, unsigned long rate);

/**
 * clk_set_rate_exclusive- set the clock rate and claim exclusivity over
 *                         clock source
 * @clk: clock source
 * @rate: desired clock rate in Hz
 *
 * This helper function allows drivers to atomically set the rate of a producer
 * and claim exclusivity over the rate control of the producer.
 *
 * It is essentially a combination of clk_set_rate() and
 * clk_rate_exclusite_get(). Caller must balance this call with a call to
 * clk_rate_exclusive_put()
 *
 * Returns success (0) or negative errno.
 */
int clk_set_rate_exclusive(struct clk *clk, unsigned long rate);

/**
 * clk_has_parent - check if a clock is a possible parent for another
 * @clk: clock source
 * @parent: parent clock source
 *
 * This function can be used in drivers that need to check that a clock can be
 * the parent of another without actually changing the parent.
 *
 * Returns true if @parent is a possible parent for @clk, false otherwise.
 */
bool clk_has_parent(struct clk *clk, struct clk *parent);

/**
 * clk_set_rate_range - set a rate range for a clock source
 * @clk: clock source
 * @min: desired minimum clock rate in Hz, inclusive
 * @max: desired maximum clock rate in Hz, inclusive
 *
 * Returns success (0) or negative errno.
 */
int clk_set_rate_range(struct clk *clk, unsigned long min, unsigned long max);

/**
 * clk_set_min_rate - set a minimum clock rate for a clock source
 * @clk: clock source
 * @rate: desired minimum clock rate in Hz, inclusive
 *
 * Returns success (0) or negative errno.
 */
int clk_set_min_rate(struct clk *clk, unsigned long rate);

/**
 * clk_set_max_rate - set a maximum clock rate for a clock source
 * @clk: clock source
 * @rate: desired maximum clock rate in Hz, inclusive
 *
 * Returns success (0) or negative errno.
 */
int clk_set_max_rate(struct clk *clk, unsigned long rate);

/**
 * clk_set_parent - set the parent clock source for this clock
 * @clk: clock source
 * @parent: parent clock source
 *
 * Returns success (0) or negative errno.
 */
int clk_set_parent(struct clk *clk, struct clk *parent);

/**
 * clk_get_parent - get the parent clock source for this clock
 * @clk: clock source
 *
 * Returns struct clk corresponding to parent clock source, or
 * valid IS_ERR() condition containing errno.
 */
struct clk *clk_get_parent(struct clk *clk);

/**
 * clk_get_sys - get a clock based upon the device name
 * @dev_id: device name
 * @con_id: connection ID
 *
 * Returns a struct clk corresponding to the clock producer, or
 * valid IS_ERR() condition containing errno.  The implementation
 * uses @dev_id and @con_id to determine the clock consumer, and
 * thereby the clock producer. In contrast to clk_get() this function
 * takes the device name instead of the device itself for identification.
 *
 * Drivers must assume that the clock source is not enabled.
 *
 * clk_get_sys should not be called from within interrupt context.
 */
struct clk *clk_get_sys(const char *dev_id, const char *con_id);

/**
 * clk_save_context - save clock context for poweroff
 *
 * Saves the context of the clock register for powerstates in which the
 * contents of the registers will be lost. Occurs deep within the suspend
 * code so locking is not necessary.
 */
int clk_save_context(void);

/**
 * clk_restore_context - restore clock context after poweroff
 *
 * This occurs with all clocks enabled. Occurs deep within the resume code
 * so locking is not necessary.
 */
void clk_restore_context(void);

#else /* !CONFIG_HAVE_CLK */

static inline struct clk *clk_get(struct device *dev, const char *id)
{
	return NULL;
}

static inline int __must_check clk_bulk_get(struct device *dev, int num_clks,
					    struct clk_bulk_data *clks)
{
	return 0;
}

static inline int __must_check clk_bulk_get_optional(struct device *dev,
				int num_clks, struct clk_bulk_data *clks)
{
	return 0;
}

static inline int __must_check clk_bulk_get_all(struct device *dev,
					 struct clk_bulk_data **clks)
{
	return 0;
}

static inline struct clk *devm_clk_get(struct device *dev, const char *id)
{
	return NULL;
}

static inline struct clk *devm_clk_get_optional(struct device *dev,
						const char *id)
{
	return NULL;
}

static inline int __must_check devm_clk_bulk_get(struct device *dev, int num_clks,
						 struct clk_bulk_data *clks)
{
	return 0;
}

static inline int __must_check devm_clk_bulk_get_optional(struct device *dev,
				int num_clks, struct clk_bulk_data *clks)
{
	return 0;
}

static inline int __must_check devm_clk_bulk_get_all(struct device *dev,
						     struct clk_bulk_data **clks)
{

	return 0;
}

static inline struct clk *devm_get_clk_from_child(struct device *dev,
				struct device_node *np, const char *con_id)
{
	return NULL;
}

static inline void clk_put(struct clk *clk) {}

static inline void clk_bulk_put(int num_clks, struct clk_bulk_data *clks) {}

static inline void clk_bulk_put_all(int num_clks, struct clk_bulk_data *clks) {}

static inline void devm_clk_put(struct device *dev, struct clk *clk) {}


static inline int clk_rate_exclusive_get(struct clk *clk)
{
	return 0;
}

static inline void clk_rate_exclusive_put(struct clk *clk) {}

static inline int clk_enable(struct clk *clk)
{
	return 0;
}

static inline int __must_check clk_bulk_enable(int num_clks,
					       const struct clk_bulk_data *clks)
{
	return 0;
}

static inline void clk_disable(struct clk *clk) {}


static inline void clk_bulk_disable(int num_clks,
				    const struct clk_bulk_data *clks) {}

static inline unsigned long clk_get_rate(struct clk *clk)
{
	return 0;
}

static inline int clk_set_rate(struct clk *clk, unsigned long rate)
{
	return 0;
}

static inline int clk_set_rate_exclusive(struct clk *clk, unsigned long rate)
{
	return 0;
}

static inline long clk_round_rate(struct clk *clk, unsigned long rate)
{
	return 0;
}

static inline bool clk_has_parent(struct clk *clk, struct clk *parent)
{
	return true;
}

static inline int clk_set_rate_range(struct clk *clk, unsigned long min,
				     unsigned long max)
{
	return 0;
}

static inline int clk_set_min_rate(struct clk *clk, unsigned long rate)
{
	return 0;
}

static inline int clk_set_max_rate(struct clk *clk, unsigned long rate)
{
	return 0;
}

static inline int clk_set_parent(struct clk *clk, struct clk *parent)
{
	return 0;
}

static inline struct clk *clk_get_parent(struct clk *clk)
{
	return NULL;
}

static inline struct clk *clk_get_sys(const char *dev_id, const char *con_id)
{
	return NULL;
}

static inline int clk_save_context(void)
{
	return 0;
}

static inline void clk_restore_context(void) {}

#endif

/* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
static inline int clk_prepare_enable(struct clk *clk)
{
	int ret;

	ret = clk_prepare(clk);
	if (ret)
		return ret;
	ret = clk_enable(clk);
	if (ret)
		clk_unprepare(clk);

	return ret;
}

/* clk_disable_unprepare helps cases using clk_disable in non-atomic context. */
static inline void clk_disable_unprepare(struct clk *clk)
{
	clk_disable(clk);
	clk_unprepare(clk);
}

static inline int __must_check
clk_bulk_prepare_enable(int num_clks, const struct clk_bulk_data *clks)
{
	int ret;

	ret = clk_bulk_prepare(num_clks, clks);
	if (ret)
		return ret;
	ret = clk_bulk_enable(num_clks, clks);
	if (ret)
		clk_bulk_unprepare(num_clks, clks);

	return ret;
}

static inline void clk_bulk_disable_unprepare(int num_clks,
					      const struct clk_bulk_data *clks)
{
	clk_bulk_disable(num_clks, clks);
	clk_bulk_unprepare(num_clks, clks);
}

/**
 * clk_drop_range - Reset any range set on that clock
 * @clk: clock source
 *
 * Returns success (0) or negative errno.
 */
static inline int clk_drop_range(struct clk *clk)
{
	return clk_set_rate_range(clk, 0, ULONG_MAX);
}

/**
 * clk_get_optional - lookup and obtain a reference to an optional clock
 *		      producer.
 * @dev: device for clock "consumer"
 * @id: clock consumer ID
 *
 * Behaves the same as clk_get() except where there is no clock producer. In
 * this case, instead of returning -ENOENT, the function returns NULL.
 */
static inline struct clk *clk_get_optional(struct device *dev, const char *id)
{
	struct clk *clk = clk_get(dev, id);

	if (clk == ERR_PTR(-ENOENT))
		return NULL;

	return clk;
}

#if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
struct clk *of_clk_get(struct device_node *np, int index);
struct clk *of_clk_get_by_name(struct device_node *np, const char *name);
struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec);
#else
static inline struct clk *of_clk_get(struct device_node *np, int index)
{
	return ERR_PTR(-ENOENT);
}
static inline struct clk *of_clk_get_by_name(struct device_node *np,
					     const char *name)
{
	return ERR_PTR(-ENOENT);
}
static inline struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec)
{
	return ERR_PTR(-ENOENT);
}
#endif

#endif