/*

   *  linux/include/linux/clk.h

   *
   *  Copyright (C) 2004 ARM Limited.
   *  Written by Deep Blue Solutions Limited.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */

  #ifndef __LINUX_CLK_H
  #define __LINUX_CLK_H

  #include <linux/kernel.h>

  struct device;
  
  /*
   * The base API.
   */
  
  
  /*
   * struct clk - an machine class defined object / cookie.
   */
  struct clk;
  
  /**
   * clk_get - lookup and obtain a reference to a clock producer.
   * @dev: device for clock "consumer"

   * @id: clock comsumer 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_prepare - prepare a clock source
   * @clk: clock source
   *
   * This prepares the clock source for use.
   *
   * Must not be called from within atomic context.
   */
  #ifdef CONFIG_HAVE_CLK_PREPARE
  int clk_prepare(struct clk *clk);
  #else
  static inline int clk_prepare(struct clk *clk)
  {
  	might_sleep();
  	return 0;
  }
  #endif
  
  /**

   * 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_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_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);
  #else
  static inline void clk_unprepare(struct clk *clk)
  {
  	might_sleep();
  }
  #endif

  /**

   * 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);
  
  
  /*
   * 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
   *
   * 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
   *
   * Returns success (0) or negative errno.
   */
  int clk_set_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_add_alias - add a new clock alias
   * @alias: name for clock alias
   * @alias_dev_name: device name
   * @id: platform specific clock name
   * @dev: device
   *
   * Allows using generic clock names for drivers by adding a new alias.
   * Assumes clkdev, see clkdev.h for more info.
   */
  int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
  			struct device *dev);

  #endif