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 ASMARM_CLOCK_H
  12 #define ASMARM_CLOCK_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 struct 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  */
  49 int 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  */
  63 void 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  */
  70 unsigned 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  */
  80 void 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  */
  95 long 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  */
 104 int 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  */
 113 int 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  */
 122 struct clk *clk_get_parent(struct clk *clk);
 123
 124 #endif