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/*
* Copyright (c) 2015 Google, Inc
* Written by Simon Glass <sjg@chromium.org>
* Copyright (c) 2016, NVIDIA CORPORATION.
*
* SPDX-License-Identifier: GPL-2.0+
*/
#ifndef _CLK_H_
#define _CLK_H_
#include <linux/types.h>
/**
* A clock is a hardware signal that oscillates autonomously at a specific
* frequency and duty cycle. Most hardware modules require one or more clock
* signal to drive their operation. Clock signals are typically generated
* externally to the HW module consuming them, by an entity this API calls a
* clock provider. This API provides a standard means for drivers to enable and
* disable clocks, and to set the rate at which they oscillate.
*
* A driver that implements UCLASS_CLOCK is a clock provider. A provider will
* often implement multiple separate clocks, since the hardware it manages
* often has this capability. clock_uclass.h describes the interface which
* clock providers must implement.
*
* Clock consumers/clients are the HW modules driven by the clock signals. This
* header file describes the API used by drivers for those HW modules.
*/
struct udevice;
/**
* struct clk - A handle to (allowing control of) a single clock.
*
* Clients provide storage for clock handles. The content of the structure is
* managed solely by the clock API and clock drivers. A clock struct is
* initialized by "get"ing the clock struct. The clock struct is passed to all
* other clock APIs to identify which clock signal to operate upon.
*
* @dev: The device which implements the clock signal.
* @id: The clock signal ID within the provider.
*
* Currently, the clock API assumes that a single integer ID is enough to
* identify and configure any clock signal for any clock provider. If this
* assumption becomes invalid in the future, the struct could be expanded to
* either (a) add more fields to allow clock providers to store additional
* information, or (b) replace the id field with an opaque pointer, which the
* provider would dynamically allocated during its .of_xlate op, and process
* during is .request op. This may require the addition of an extra op to clean
* up the allocation.
*/
struct clk {
struct udevice *dev;
/*
* Written by of_xlate. We assume a single id is enough for now. In the
* future, we might add more fields here.
*/
unsigned long id;
};
#if CONFIG_IS_ENABLED(OF_CONTROL)
/**
* clock_get_by_index - Get/request a clock by integer index.
*
* This looks up and requests a clock. The index is relative to the client
* device; each device is assumed to have n clocks associated with it somehow,
* and this function finds and requests one of them. The mapping of client
* device clock indices to provider clocks may be via device-tree properties,
* board-provided mapping tables, or some other mechanism.
*
* @dev: The client device.
* @index: The index of the clock to request, within the client's list of
* clocks.
* @clock A pointer to a clock struct to initialize.
* @return 0 if OK, or a negative error code.
*/
int clk_get_by_index(struct udevice *dev, int index, struct clk *clk);
/**
* clock_get_by_name - Get/request a clock by name.
*
* This looks up and requests a clock. The name is relative to the client
* device; each device is assumed to have n clocks associated with it somehow,
* and this function finds and requests one of them. The mapping of client
* device clock names to provider clocks may be via device-tree properties,
* board-provided mapping tables, or some other mechanism.
*
* @dev: The client device.
* @name: The name of the clock to request, within the client's list of
* clocks.
* @clock: A pointer to a clock struct to initialize.
* @return 0 if OK, or a negative error code.
*/
int clk_get_by_name(struct udevice *dev, const char *name, struct clk *clk);
#else
static inline int clk_get_by_index(struct udevice *dev, int index,
struct clk *clk)
{
return -ENOSYS;
}
static int clk_get_by_name(struct udevice *dev, const char *name,
struct clk *clk)
{
return -ENOSYS;
}
#endif
/**
* clk_request - Request a clock by provider-specific ID.
*
* This requests a clock using a provider-specific ID. Generally, this function
* should not be used, since clk_get_by_index/name() provide an interface that
* better separates clients from intimate knowledge of clock providers.
* However, this function may be useful in core SoC-specific code.
*
* @dev: The clock provider device.
* @clock: A pointer to a clock struct to initialize. The caller must
* have already initialized any field in this struct which the
* clock provider uses to identify the clock.
* @return 0 if OK, or a negative error code.
*/
int clk_request(struct udevice *dev, struct clk *clk);
/**
* clock_free - Free a previously requested clock.
*
* @clock: A clock struct that was previously successfully requested by
* clk_request/get_by_*().
* @return 0 if OK, or a negative error code.
*/
int clk_free(struct clk *clk);
/**
* clk_get_rate() - Get current clock rate.
*
* @clk: A clock struct that was previously successfully requested by
* clk_request/get_by_*().
* @return clock rate in Hz, or -ve error code.
*/
ulong clk_get_rate(struct clk *clk);
/**
* clk_set_rate() - Set current clock rate.
*
* @clk: A clock struct that was previously successfully requested by
* clk_request/get_by_*().
* @rate: New clock rate in Hz.
* @return new rate, or -ve error code.
*/
ulong clk_set_rate(struct clk *clk, ulong rate);
/**
* clk_enable() - Enable (turn on) a clock.
*
* @clk: A clock struct that was previously successfully requested by
* clk_request/get_by_*().
* @return zero on success, or -ve error code.
*/
int clk_enable(struct clk *clk);
/**
* clk_disable() - Disable (turn off) a clock.
*
* @clk: A clock struct that was previously successfully requested by
* clk_request/get_by_*().
* @return zero on success, or -ve error code.
*/
int clk_disable(struct clk *clk);
int soc_clk_dump(void);
#endif
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