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 #include <linux/kernel.h>
  15
  16 struct device;
  17
  18 /*
  19  * The base API.
  20  */
  21
  22
  23 /*
  24  * struct clk - an machine class defined object / cookie.
  25  */
  26 struct clk;
  27
  28 /**
  29  * clk_get - lookup and obtain a reference to a clock producer.
  30  * @dev: device for clock "consumer"
  31  * @id: clock comsumer ID
  32  *
  33  * Returns a struct clk corresponding to the clock producer, or
  34  * valid IS_ERR() condition containing errno.  The implementation
  35  * uses @dev and @id to determine the clock consumer, and thereby
  36  * the clock producer.  (IOW, @id may be identical strings, but
  37  * clk_get may return different clock producers depending on @dev.)
  38  *
  39  * Drivers must assume that the clock source is not enabled.
  40  *
  41  * clk_get should not be called from within interrupt context.
  42  */
  43 struct clk *clk_get(struct device *dev, const char *id);
  44
  45 /**
  46  * clk_prepare - prepare a clock source
  47  * @clk: clock source
  48  *
  49  * This prepares the clock source for use.
  50  *
  51  * Must not be called from within atomic context.
  52  */
  53 #ifdef CONFIG_HAVE_CLK_PREPARE
  54 int clk_prepare(struct clk *clk);
  55 #else
  56 static inline int clk_prepare(struct clk *clk)
  57 {
  58         might_sleep();
  59         return 0;
  60 }
  61 #endif
  62
  63 /**
  64  * clk_enable - inform the system when the clock source should be running.
  65  * @clk: clock source
  66  *
  67  * If the clock can not be enabled/disabled, this should return success.
  68  *
  69  * May be called from atomic contexts.
  70  *
  71  * Returns success (0) or negative errno.
  72  */
  73 int clk_enable(struct clk *clk);
  74
  75 /**
  76  * clk_disable - inform the system when the clock source is no longer required.
  77  * @clk: clock source
  78  *
  79  * Inform the system that a clock source is no longer required by
  80  * a driver and may be shut down.
  81  *
  82  * May be called from atomic contexts.
  83  *
  84  * Implementation detail: if the clock source is shared between
  85  * multiple drivers, clk_enable() calls must be balanced by the
  86  * same number of clk_disable() calls for the clock source to be
  87  * disabled.
  88  */
  89 void clk_disable(struct clk *clk);
  90
  91
  92 /**
  93  * clk_unprepare - undo preparation of a clock source
  94  * @clk: clock source
  95  *
  96  * This undoes a previously prepared clock.  The caller must balance
  97  * the number of prepare and unprepare calls.
  98  *
  99  * Must not be called from within atomic context.
 100  */
 101 #ifdef CONFIG_HAVE_CLK_PREPARE
 102 void clk_unprepare(struct clk *clk);
 103 #else
 104 static inline void clk_unprepare(struct clk *clk)
 105 {
 106         might_sleep();
 107 }
 108 #endif
 109
 110 /* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
 111 static inline int clk_prepare_enable(struct clk *clk)
 112 {
 113         int ret;
 114
 115         ret = clk_prepare(clk);
 116         if (ret)
 117                 return ret;
 118         ret = clk_enable(clk);
 119         if (ret)
 120                 clk_unprepare(clk);
 121
 122         return ret;
 123 }
 124
 125 /* clk_disable_unprepare helps cases using clk_disable in non-atomic context. */
 126 static inline void clk_disable_unprepare(struct clk *clk)
 127 {
 128         clk_disable(clk);
 129         clk_unprepare(clk);
 130 }
 131
 132 /**
 133  * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
 134  *                This is only valid once the clock source has been enabled.
 135  * @clk: clock source
 136  */
 137 unsigned long clk_get_rate(struct clk *clk);
 138
 139 /**
 140  * clk_put      - "free" the clock source
 141  * @clk: clock source
 142  *
 143  * Note: drivers must ensure that all clk_enable calls made on this
 144  * clock source are balanced by clk_disable calls prior to calling
 145  * this function.
 146  *
 147  * clk_put should not be called from within interrupt context.
 148  */
 149 void clk_put(struct clk *clk);
 150
 151
 152 /*
 153  * The remaining APIs are optional for machine class support.
 154  */
 155
 156
 157 /**
 158  * clk_round_rate - adjust a rate to the exact rate a clock can provide
 159  * @clk: clock source
 160  * @rate: desired clock rate in Hz
 161  *
 162  * Returns rounded clock rate in Hz, or negative errno.
 163  */
 164 long clk_round_rate(struct clk *clk, unsigned long rate);
 165
 166 /**
 167  * clk_set_rate - set the clock rate for a clock source
 168  * @clk: clock source
 169  * @rate: desired clock rate in Hz
 170  *
 171  * Returns success (0) or negative errno.
 172  */
 173 int clk_set_rate(struct clk *clk, unsigned long rate);
 174
 175 /**
 176  * clk_set_parent - set the parent clock source for this clock
 177  * @clk: clock source
 178  * @parent: parent clock source
 179  *
 180  * Returns success (0) or negative errno.
 181  */
 182 int clk_set_parent(struct clk *clk, struct clk *parent);
 183
 184 /**
 185  * clk_get_parent - get the parent clock source for this clock
 186  * @clk: clock source
 187  *
 188  * Returns struct clk corresponding to parent clock source, or
 189  * valid IS_ERR() condition containing errno.
 190  */
 191 struct clk *clk_get_parent(struct clk *clk);
 192
 193 /**
 194  * clk_get_sys - get a clock based upon the device name
 195  * @dev_id: device name
 196  * @con_id: connection ID
 197  *
 198  * Returns a struct clk corresponding to the clock producer, or
 199  * valid IS_ERR() condition containing errno.  The implementation
 200  * uses @dev_id and @con_id to determine the clock consumer, and
 201  * thereby the clock producer. In contrast to clk_get() this function
 202  * takes the device name instead of the device itself for identification.
 203  *
 204  * Drivers must assume that the clock source is not enabled.
 205  *
 206  * clk_get_sys should not be called from within interrupt context.
 207  */
 208 struct clk *clk_get_sys(const char *dev_id, const char *con_id);
 209
 210 /**
 211  * clk_add_alias - add a new clock alias
 212  * @alias: name for clock alias
 213  * @alias_dev_name: device name
 214  * @id: platform specific clock name
 215  * @dev: device
 216  *
 217  * Allows using generic clock names for drivers by adding a new alias.
 218  * Assumes clkdev, see clkdev.h for more info.
 219  */
 220 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 221                         struct device *dev);
 222
 223 #endif