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 /* 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 <mturquette@linaro.org>
  */
 #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_prepared - devm_clk_get() + clk_prepare()
  * @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.)
  *
  * The returned clk (if valid) is prepared. Drivers must however assume
  * that the clock is not enabled.
  *
  * The clock will automatically be unprepared and freed when the device
  * is unbound from the bus.
  */
 struct clk *devm_clk_get_prepared(struct device *dev, const char *id);
 
 /**
  * devm_clk_get_enabled - devm_clk_get() + clk_prepare_enable()
  * @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.)
  *
  * The returned clk (if valid) is prepared and enabled.
  *
  * The clock will automatically be disabled, unprepared and freed
  * when the device is unbound from the bus.
  */
 struct clk *devm_clk_get_enabled(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_clk_get_optional_prepared - devm_clk_get_optional() + clk_prepare()
  * @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_prepared().
  *
  * The returned clk (if valid) is prepared. Drivers must however
  * assume that the clock is not enabled.
  *
  * The clock will automatically be unprepared and freed when the
  * device is unbound from the bus.
  */
 struct clk *devm_clk_get_optional_prepared(struct device *dev, const char *id);
 
 /**
  * devm_clk_get_optional_enabled - devm_clk_get_optional() +
  *                                 clk_prepare_enable()
  * @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_enabled().
  *
  * The returned clk (if valid) is prepared and enabled.
  *
  * The clock will automatically be disabled, unprepared and freed
  * when the device is unbound from the bus.
  */
 struct clk *devm_clk_get_optional_enabled(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_prepared(struct device *dev,
                         const char *id)
 {
     return NULL;
 }
 
 static inline struct clk *devm_clk_get_enabled(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 struct clk *devm_clk_get_optional_prepared(struct device *dev,
                              const char *id)
 {
     return NULL;
 }
 
 static inline struct clk *devm_clk_get_optional_enabled(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

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