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  *  Copyright (C) 2011-2012 Linaro Ltd <mturquette@linaro.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12 #ifndef __LINUX_CLK_H
  13 #define __LINUX_CLK_H
  14
  15 #include <linux/kernel.h>
  16 #include <linux/notifier.h>
  17
  18 struct device;
  19
  20 struct clk;
  21
  22 #ifdef CONFIG_COMMON_CLK
  23
  24 /**
  25  * DOC: clk notifier callback types
  26  *
  27  * PRE_RATE_CHANGE - called immediately before the clk rate is changed,
  28  *     to indicate that the rate change will proceed.  Drivers must
  29  *     immediately terminate any operations that will be affected by the
  30  *     rate change.  Callbacks may either return NOTIFY_DONE or
  31  *     NOTIFY_STOP.
  32  *
  33  * ABORT_RATE_CHANGE: called if the rate change failed for some reason
  34  *     after PRE_RATE_CHANGE.  In this case, all registered notifiers on
  35  *     the clk will be called with ABORT_RATE_CHANGE. Callbacks must
  36  *     always return NOTIFY_DONE.
  37  *
  38  * POST_RATE_CHANGE - called after the clk rate change has successfully
  39  *     completed.  Callbacks must always return NOTIFY_DONE.
  40  *
  41  */
  42 #define PRE_RATE_CHANGE                 BIT(0)
  43 #define POST_RATE_CHANGE                BIT(1)
  44 #define ABORT_RATE_CHANGE               BIT(2)
  45
  46 /**
  47  * struct clk_notifier - associate a clk with a notifier
  48  * @clk: struct clk * to associate the notifier with
  49  * @notifier_head: a blocking_notifier_head for this clk
  50  * @node: linked list pointers
  51  *
  52  * A list of struct clk_notifier is maintained by the notifier code.
  53  * An entry is created whenever code registers the first notifier on a
  54  * particular @clk.  Future notifiers on that @clk are added to the
  55  * @notifier_head.
  56  */
  57 struct clk_notifier {
  58         struct clk                      *clk;
  59         struct srcu_notifier_head       notifier_head;
  60         struct list_head                node;
  61 };
  62
  63 /**
  64  * struct clk_notifier_data - rate data to pass to the notifier callback
  65  * @clk: struct clk * being changed
  66  * @old_rate: previous rate of this clk
  67  * @new_rate: new rate of this clk
  68  *
  69  * For a pre-notifier, old_rate is the clk's rate before this rate
  70  * change, and new_rate is what the rate will be in the future.  For a
  71  * post-notifier, old_rate and new_rate are both set to the clk's
  72  * current rate (this was done to optimize the implementation).
  73  */
  74 struct clk_notifier_data {
  75         struct clk              *clk;
  76         unsigned long           old_rate;
  77         unsigned long           new_rate;
  78 };
  79
  80 int clk_notifier_register(struct clk *clk, struct notifier_block *nb);
  81
  82 int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb);
  83
  84 #endif /* !CONFIG_COMMON_CLK */
  85
  86 /**
  87  * clk_get - lookup and obtain a reference to a clock producer.
  88  * @dev: device for clock "consumer"
  89  * @id: clock comsumer ID
  90  *
  91  * Returns a struct clk corresponding to the clock producer, or
  92  * valid IS_ERR() condition containing errno.  The implementation
  93  * uses @dev and @id to determine the clock consumer, and thereby
  94  * the clock producer.  (IOW, @id may be identical strings, but
  95  * clk_get may return different clock producers depending on @dev.)
  96  *
  97  * Drivers must assume that the clock source is not enabled.
  98  *
  99  * clk_get should not be called from within interrupt context.
 100  */
 101 struct clk *clk_get(struct device *dev, const char *id);
 102
 103 /**
 104  * clk_prepare - prepare a clock source
 105  * @clk: clock source
 106  *
 107  * This prepares the clock source for use.
 108  *
 109  * Must not be called from within atomic context.
 110  */
 111 #ifdef CONFIG_HAVE_CLK_PREPARE
 112 int clk_prepare(struct clk *clk);
 113 #else
 114 static inline int clk_prepare(struct clk *clk)
 115 {
 116         might_sleep();
 117         return 0;
 118 }
 119 #endif
 120
 121 /**
 122  * clk_enable - inform the system when the clock source should be running.
 123  * @clk: clock source
 124  *
 125  * If the clock can not be enabled/disabled, this should return success.
 126  *
 127  * May be called from atomic contexts.
 128  *
 129  * Returns success (0) or negative errno.
 130  */
 131 int clk_enable(struct clk *clk);
 132
 133 /**
 134  * clk_disable - inform the system when the clock source is no longer required.
 135  * @clk: clock source
 136  *
 137  * Inform the system that a clock source is no longer required by
 138  * a driver and may be shut down.
 139  *
 140  * May be called from atomic contexts.
 141  *
 142  * Implementation detail: if the clock source is shared between
 143  * multiple drivers, clk_enable() calls must be balanced by the
 144  * same number of clk_disable() calls for the clock source to be
 145  * disabled.
 146  */
 147 void clk_disable(struct clk *clk);
 148
 149
 150 /**
 151  * clk_unprepare - undo preparation of a clock source
 152  * @clk: clock source
 153  *
 154  * This undoes a previously prepared clock.  The caller must balance
 155  * the number of prepare and unprepare calls.
 156  *
 157  * Must not be called from within atomic context.
 158  */
 159 #ifdef CONFIG_HAVE_CLK_PREPARE
 160 void clk_unprepare(struct clk *clk);
 161 #else
 162 static inline void clk_unprepare(struct clk *clk)
 163 {
 164         might_sleep();
 165 }
 166 #endif
 167
 168 /* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
 169 static inline int clk_prepare_enable(struct clk *clk)
 170 {
 171         int ret;
 172
 173         ret = clk_prepare(clk);
 174         if (ret)
 175                 return ret;
 176         ret = clk_enable(clk);
 177         if (ret)
 178                 clk_unprepare(clk);
 179
 180         return ret;
 181 }
 182
 183 /* clk_disable_unprepare helps cases using clk_disable in non-atomic context. */
 184 static inline void clk_disable_unprepare(struct clk *clk)
 185 {
 186         clk_disable(clk);
 187         clk_unprepare(clk);
 188 }
 189
 190 /**
 191  * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
 192  *                This is only valid once the clock source has been enabled.
 193  * @clk: clock source
 194  */
 195 unsigned long clk_get_rate(struct clk *clk);
 196
 197 /**
 198  * clk_put      - "free" the clock source
 199  * @clk: clock source
 200  *
 201  * Note: drivers must ensure that all clk_enable calls made on this
 202  * clock source are balanced by clk_disable calls prior to calling
 203  * this function.
 204  *
 205  * clk_put should not be called from within interrupt context.
 206  */
 207 void clk_put(struct clk *clk);
 208
 209
 210 /*
 211  * The remaining APIs are optional for machine class support.
 212  */
 213
 214
 215 /**
 216  * clk_round_rate - adjust a rate to the exact rate a clock can provide
 217  * @clk: clock source
 218  * @rate: desired clock rate in Hz
 219  *
 220  * Returns rounded clock rate in Hz, or negative errno.
 221  */
 222 long clk_round_rate(struct clk *clk, unsigned long rate);
 223
 224 /**
 225  * clk_set_rate - set the clock rate for a clock source
 226  * @clk: clock source
 227  * @rate: desired clock rate in Hz
 228  *
 229  * Returns success (0) or negative errno.
 230  */
 231 int clk_set_rate(struct clk *clk, unsigned long rate);
 232
 233 /**
 234  * clk_set_parent - set the parent clock source for this clock
 235  * @clk: clock source
 236  * @parent: parent clock source
 237  *
 238  * Returns success (0) or negative errno.
 239  */
 240 int clk_set_parent(struct clk *clk, struct clk *parent);
 241
 242 /**
 243  * clk_get_parent - get the parent clock source for this clock
 244  * @clk: clock source
 245  *
 246  * Returns struct clk corresponding to parent clock source, or
 247  * valid IS_ERR() condition containing errno.
 248  */
 249 struct clk *clk_get_parent(struct clk *clk);
 250
 251 /**
 252  * clk_get_sys - get a clock based upon the device name
 253  * @dev_id: device name
 254  * @con_id: connection ID
 255  *
 256  * Returns a struct clk corresponding to the clock producer, or
 257  * valid IS_ERR() condition containing errno.  The implementation
 258  * uses @dev_id and @con_id to determine the clock consumer, and
 259  * thereby the clock producer. In contrast to clk_get() this function
 260  * takes the device name instead of the device itself for identification.
 261  *
 262  * Drivers must assume that the clock source is not enabled.
 263  *
 264  * clk_get_sys should not be called from within interrupt context.
 265  */
 266 struct clk *clk_get_sys(const char *dev_id, const char *con_id);
 267
 268 /**
 269  * clk_add_alias - add a new clock alias
 270  * @alias: name for clock alias
 271  * @alias_dev_name: device name
 272  * @id: platform specific clock name
 273  * @dev: device
 274  *
 275  * Allows using generic clock names for drivers by adding a new alias.
 276  * Assumes clkdev, see clkdev.h for more info.
 277  */
 278 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 279                         struct device *dev);
 280
 281 #endif