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 *
  39 * clk_get should not be called from within interrupt context.
  40 */
  41struct clk *clk_get(struct device *dev, const char *id);
  42
  43/**
  44 * clk_enable - inform the system when the clock source should be running.
  45 * @clk: clock source
  46 *
  47 * If the clock can not be enabled/disabled, this should return success.
  48 *
  49 * Returns success (0) or negative errno.
  50 */
  51int clk_enable(struct clk *clk);
  52
  53/**
  54 * clk_disable - inform the system when the clock source is no longer required.
  55 * @clk: clock source
  56 *
  57 * Inform the system that a clock source is no longer required by
  58 * a driver and may be shut down.
  59 *
  60 * Implementation detail: if the clock source is shared between
  61 * multiple drivers, clk_enable() calls must be balanced by the
  62 * same number of clk_disable() calls for the clock source to be
  63 * disabled.
  64 */
  65void clk_disable(struct clk *clk);
  66
  67/**
  68 * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
  69 *                This is only valid once the clock source has been enabled.
  70 * @clk: clock source
  71 */
  72unsigned long clk_get_rate(struct clk *clk);
  73
  74/**
  75 * clk_put      - "free" the clock source
  76 * @clk: clock source
  77 *
  78 * Note: drivers must ensure that all clk_enable calls made on this
  79 * clock source are balanced by clk_disable calls prior to calling
  80 * this function.
  81 *
  82 * clk_put should not be called from within interrupt context.
  83 */
  84void clk_put(struct clk *clk);
  85
  86
  87/*
  88 * The remaining APIs are optional for machine class support.
  89 */
  90
  91
  92/**
  93 * clk_round_rate - adjust a rate to the exact rate a clock can provide
  94 * @clk: clock source
  95 * @rate: desired clock rate in Hz
  96 *
  97 * Returns rounded clock rate in Hz, or negative errno.
  98 */
  99long clk_round_rate(struct clk *clk, unsigned long rate);
 100 
 101/**
 102 * clk_set_rate - set the clock rate for a clock source
 103 * @clk: clock source
 104 * @rate: desired clock rate in Hz
 105 *
 106 * Returns success (0) or negative errno.
 107 */
 108int clk_set_rate(struct clk *clk, unsigned long rate);
 109 
 110/**
 111 * clk_set_parent - set the parent clock source for this clock
 112 * @clk: clock source
 113 * @parent: parent clock source
 114 *
 115 * Returns success (0) or negative errno.
 116 */
 117int clk_set_parent(struct clk *clk, struct clk *parent);
 118
 119/**
 120 * clk_get_parent - get the parent clock source for this clock
 121 * @clk: clock source
 122 *
 123 * Returns struct clk corresponding to parent clock source, or
 124 * valid IS_ERR() condition containing errno.
 125 */
 126struct clk *clk_get_parent(struct clk *clk);
 127
 128/**
 129 * clk_get_sys - get a clock based upon the device name
 130 * @dev_id: device name
 131 * @con_id: connection ID
 132 *
 133 * Returns a struct clk corresponding to the clock producer, or
 134 * valid IS_ERR() condition containing errno.  The implementation
 135 * uses @dev_id and @con_id to determine the clock consumer, and
 136 * thereby the clock producer. In contrast to clk_get() this function
 137 * takes the device name instead of the device itself for identification.
 138 *
 139 * Drivers must assume that the clock source is not enabled.
 140 *
 141 * clk_get_sys should not be called from within interrupt context.
 142 */
 143struct clk *clk_get_sys(const char *dev_id, const char *con_id);
 144
 145/**
 146 * clk_add_alias - add a new clock alias
 147 * @alias: name for clock alias
 148 * @alias_dev_name: device name
 149 * @id: platform specific clock name
 150 * @dev: device
 151 *
 152 * Allows using generic clock names for drivers by adding a new alias.
 153 * Assumes clkdev, see clkdev.h for more info.
 154 */
 155int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 156                        struct device *dev);
 157
 158#endif
 159