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
  14 struct device;
  15
  16 /*
  17  * The base API.
  18  */
  19
  20
  21 /*
  22  * struct clk - an machine class defined object / cookie.
  23  */
  24 struct 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  */
  41 struct 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  */
  51 int 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  */
  65 void 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  */
  72 unsigned 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  */
  84 void 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  */
  99 long 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  */
 108 int 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  */
 117 int 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  */
 126 struct clk *clk_get_parent(struct clk *clk);
 127
 128 #endif