LXR linux/include/linux/clk.h

   1/*
   2 *  linux/include/linux/clk.h
   3 *
   4 *  Copyright (C) 2004 ARM Limited.
   5 *  Written by Deep Blue Solutions Limited.
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License version 2 as
   9 * published by the Free Software Foundation.
  10 */
  11#ifndef __LINUX_CLK_H
  12#define __LINUX_CLK_H
  13
  14struct device;
  15
  16/*
  17 * The base API.
  18 */
  19
  20
  21/*
  22 * struct clk - an machine class defined object / cookie.
  23 */
  24struct clk;
  25
  26/**
  27 * clk_get - lookup and obtain a reference to a clock producer.
  28 * @dev: device for clock "consumer"
  29 * @id: clock comsumer ID
  30 *
  31 * Returns a struct clk corresponding to the clock producer, or
  32 * valid IS_ERR() condition containing errno.  The implementation
  33 * uses @dev and @id to determine the clock consumer, and thereby
  34 * the clock producer.  (IOW, @id may be identical strings, but
  35 * clk_get may return different clock producers depending on @dev.)
  36 *
  37 * Drivers must assume that the clock source is not enabled.
  38 */
  39struct clk *clk_get(struct device *dev, const char *id);
  40
  41/**
  42 * clk_enable - inform the system when the clock source should be running.
  43 * @clk: clock source
  44 *
  45 * If the clock can not be enabled/disabled, this should return success.
  46 *
  47 * Returns success (0) or negative errno.
  48 */
  49int clk_enable(struct clk *clk);
  50
  51/**
  52 * clk_disable - inform the system when the clock source is no longer required.
  53 * @clk: clock source
  54 *
  55 * Inform the system that a clock source is no longer required by
  56 * a driver and may be shut down.
  57 *
  58 * Implementation detail: if the clock source is shared between
  59 * multiple drivers, clk_enable() calls must be balanced by the
  60 * same number of clk_disable() calls for the clock source to be
  61 * disabled.
  62 */
  63void clk_disable(struct clk *clk);
  64
  65/**
  66 * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
  67 *                This is only valid once the clock source has been enabled.
  68 * @clk: clock source
  69 */
  70unsigned long clk_get_rate(struct clk *clk);
  71
  72/**
  73 * clk_put      - "free" the clock source
  74 * @clk: clock source
  75 *
  76 * Note: drivers must ensure that all clk_enable calls made on this
  77 * clock source are balanced by clk_disable calls prior to calling
  78 * this function.
  79 */
  80void clk_put(struct clk *clk);
  81
  82
  83/*
  84 * The remaining APIs are optional for machine class support.
  85 */
  86
  87
  88/**
  89 * clk_round_rate - adjust a rate to the exact rate a clock can provide
  90 * @clk: clock source
  91 * @rate: desired clock rate in Hz
  92 *
  93 * Returns rounded clock rate in Hz, or negative errno.
  94 */
  95long clk_round_rate(struct clk *clk, unsigned long rate);
  96 
  97/**
  98 * clk_set_rate - set the clock rate for a clock source
  99 * @clk: clock source
 100 * @rate: desired clock rate in Hz
 101 *
 102 * Returns success (0) or negative errno.
 103 */
 104int clk_set_rate(struct clk *clk, unsigned long rate);
 105 
 106/**
 107 * clk_set_parent - set the parent clock source for this clock
 108 * @clk: clock source
 109 * @parent: parent clock source
 110 *
 111 * Returns success (0) or negative errno.
 112 */
 113int clk_set_parent(struct clk *clk, struct clk *parent);
 114
 115/**
 116 * clk_get_parent - get the parent clock source for this clock
 117 * @clk: clock source
 118 *
 119 * Returns struct clk corresponding to parent clock source, or
 120 * valid IS_ERR() condition containing errno.
 121 */
 122struct clk *clk_get_parent(struct clk *clk);
 123
 124#endif
 125