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/*
* Copyright © 2017-2022 The Crust Firmware Authors.
* SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0-only
*/
#ifndef DRIVERS_CLOCK_H
#define DRIVERS_CLOCK_H
#include <device.h>
#include <stdint.h>
enum {
CLOCK_STATE_DISABLED,
CLOCK_STATE_GATED,
CLOCK_STATE_ENABLED,
};
struct clock_handle {
const struct device *dev; /**< The clock controller device. */
uint8_t id; /**< The device-specific clock identifier. */
};
/**
* Determine if a clock is active.
*
* A clock is active if it has any outstanding references. The state of the
* hardware gate, if any, is not considered.
*
* @param clock A reference to a clock.
* @return The state of the clock.
*/
bool clock_active(const struct clock_handle *clock);
/**
* Disable a clock.
*
* If the clock does not have a gate, this may have no effect on the hardware.
* The clock's parent, if any, will be left as it is.
*
* @param clock A reference to a clock.
*/
void clock_disable(const struct clock_handle *clock);
/**
* Enable a clock.
*
* If the clock does not have a gate, this may have no effect on the hardware.
* The clock's parent, if any, will also be enabled.
*
* @param clock A reference to a clock.
*/
void clock_enable(const struct clock_handle *clock);
/**
* Get a reference to a clock and its controller device, and enable the clock.
*
* If the clock does not have a gate, this may have no effect on the hardware.
* The clock's parent, if any, will also be enabled.
*
* @param clock A handle specifying the clock.
*/
void clock_get(const struct clock_handle *clock);
/**
* Get the current rate of a clock, as calculated from the hardware.
*
* This function returns the frequency the clock runs at when ungated,
* regardless of if the clock is currently gated.
*
* @param clock A reference to a clock.
* @return The clock frequency in Hz.
*/
uint32_t clock_get_rate(const struct clock_handle *clock);
/**
* Get the current state of a clock, as determined from the hardware.
*
* @param clock A reference to a clock.
* @return One of the enumerated clock states.
*/
uint32_t clock_get_state(const struct clock_handle *clock);
/**
* Release a reference to a clock and its controller device.
*
* If this is the last reference to a clock, that clock (and its ancestors
* recursively, if they have no other consumers) will be disabled.
*
* @param clock A reference to a clock.
*/
void clock_put(const struct clock_handle *clock);
#endif /* DRIVERS_CLOCK_H */
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