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    /*
     * Copyright (c) 2015 Google, Inc
     * Written by Simon Glass <sjg@chromium.org>
    
     * Copyright (c) 2016, NVIDIA CORPORATION.
    
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     *
     * SPDX-License-Identifier:	GPL-2.0+
     */
    
    
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    #ifndef _CLK_H_
    #define _CLK_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 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.
    
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    	 */
    
    #if CONFIG_IS_ENABLED(OF_CONTROL) && CONFIG_IS_ENABLED(CLK)
    
    struct phandle_1_arg;
    
    int clk_get_by_index_platdata(struct udevice *dev, int index,
    
    			      struct phandle_1_arg *cells, struct clk *clk);
    
    /**
     * 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.
    
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     *
    
     * 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.
    
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     */
    
    int clk_get_by_name(struct udevice *dev, const char *name, struct clk *clk);
    
    
    /**
     * clk_release_all() - Disable (turn off)/Free an array of previously
     * requested clocks.
     *
     * For each clock contained in the clock array, this function will check if
     * clock has been previously requested and then will disable and free it.
     *
     * @clk:	A clock struct array that was previously successfully
     *		requested by clk_request/get_by_*().
     * @count	Number of clock contained in the array
     * @return zero on success, or -ve error code.
     */
    int clk_release_all(struct clk *clk, int count);
    
    
    #else
    static inline int clk_get_by_index(struct udevice *dev, int index,
    				   struct clk *clk)
    {
    	return -ENOSYS;
    }
    
    static inline int clk_get_by_name(struct udevice *dev, const char *name,
    			   struct clk *clk)
    {
    	return -ENOSYS;
    }
    
    
    static inline int clk_release_all(struct clk *clk, int count)
    {
    	return -ENOSYS;
    }
    
    
     * clk_request - Request a clock by provider-specific ID.
    
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     *
    
     * 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.
    
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     */
    
    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);
    
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    /**
    
     * clk_get_rate() - Get current clock rate.
    
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     *
    
     * @clk:	A clock struct that was previously successfully requested by
     *		clk_request/get_by_*().
     * @return clock rate in Hz, or -ve error code.
    
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     */
    
    ulong clk_get_rate(struct clk *clk);
    
     * clk_set_rate() - Set current clock rate.
    
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     *
    
     * @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.
    
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     */
    
    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