path: root/include/linux/clk.h

/* 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);

/**
 * 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