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
  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  * devm_clk_get - lookup and obtain a managed reference to a clock producer.
 105  * @dev: device for clock "consumer"
 106  * @id: clock comsumer ID
 107  *
 108  * Returns a struct clk corresponding to the clock producer, or
 109  * valid IS_ERR() condition containing errno.  The implementation
 110  * uses @dev and @id to determine the clock consumer, and thereby
 111  * the clock producer.  (IOW, @id may be identical strings, but
 112  * clk_get may return different clock producers depending on @dev.)
 113  *
 114  * Drivers must assume that the clock source is not enabled.
 115  *
 116  * devm_clk_get should not be called from within interrupt context.
 117  *
 118  * The clock will automatically be freed when the device is unbound
 119  * from the bus.
 120  */
 121 struct clk *devm_clk_get(struct device *dev, const char *id);
 122
 123 /**
 124  * clk_prepare - prepare a clock source
 125  * @clk: clock source
 126  *
 127  * This prepares the clock source for use.
 128  *
 129  * Must not be called from within atomic context.
 130  */
 131 #ifdef CONFIG_HAVE_CLK_PREPARE
 132 int clk_prepare(struct clk *clk);
 133 #else
 134 static inline int clk_prepare(struct clk *clk)
 135 {
 136         might_sleep();
 137         return 0;
 138 }
 139 #endif
 140
 141 /**
 142  * clk_enable - inform the system when the clock source should be running.
 143  * @clk: clock source
 144  *
 145  * If the clock can not be enabled/disabled, this should return success.
 146  *
 147  * May be called from atomic contexts.
 148  *
 149  * Returns success (0) or negative errno.
 150  */
 151 int clk_enable(struct clk *clk);
 152
 153 /**
 154  * clk_disable - inform the system when the clock source is no longer required.
 155  * @clk: clock source
 156  *
 157  * Inform the system that a clock source is no longer required by
 158  * a driver and may be shut down.
 159  *
 160  * May be called from atomic contexts.
 161  *
 162  * Implementation detail: if the clock source is shared between
 163  * multiple drivers, clk_enable() calls must be balanced by the
 164  * same number of clk_disable() calls for the clock source to be
 165  * disabled.
 166  */
 167 void clk_disable(struct clk *clk);
 168
 169
 170 /**
 171  * clk_unprepare - undo preparation of a clock source
 172  * @clk: clock source
 173  *
 174  * This undoes a previously prepared clock.  The caller must balance
 175  * the number of prepare and unprepare calls.
 176  *
 177  * Must not be called from within atomic context.
 178  */
 179 #ifdef CONFIG_HAVE_CLK_PREPARE
 180 void clk_unprepare(struct clk *clk);
 181 #else
 182 static inline void clk_unprepare(struct clk *clk)
 183 {
 184         might_sleep();
 185 }
 186 #endif
 187
 188 /* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
 189 static inline int clk_prepare_enable(struct clk *clk)
 190 {
 191         int ret;
 192
 193         ret = clk_prepare(clk);
 194         if (ret)
 195                 return ret;
 196         ret = clk_enable(clk);
 197         if (ret)
 198                 clk_unprepare(clk);
 199
 200         return ret;
 201 }
 202
 203 /* clk_disable_unprepare helps cases using clk_disable in non-atomic context. */
 204 static inline void clk_disable_unprepare(struct clk *clk)
 205 {
 206         clk_disable(clk);
 207         clk_unprepare(clk);
 208 }
 209
 210 /**
 211  * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
 212  *                This is only valid once the clock source has been enabled.
 213  * @clk: clock source
 214  */
 215 unsigned long clk_get_rate(struct clk *clk);
 216
 217 /**
 218  * clk_put      - "free" the clock source
 219  * @clk: clock source
 220  *
 221  * Note: drivers must ensure that all clk_enable calls made on this
 222  * clock source are balanced by clk_disable calls prior to calling
 223  * this function.
 224  *
 225  * clk_put should not be called from within interrupt context.
 226  */
 227 void clk_put(struct clk *clk);
 228
 229 /**
 230  * devm_clk_put - "free" a managed clock source
 231  * @dev: device used to acuqire the clock
 232  * @clk: clock source acquired with devm_clk_get()
 233  *
 234  * Note: drivers must ensure that all clk_enable calls made on this
 235  * clock source are balanced by clk_disable calls prior to calling
 236  * this function.
 237  *
 238  * clk_put should not be called from within interrupt context.
 239  */
 240 void devm_clk_put(struct device *dev, struct clk *clk);
 241
 242 /*
 243  * The remaining APIs are optional for machine class support.
 244  */
 245
 246
 247 /**
 248  * clk_round_rate - adjust a rate to the exact rate a clock can provide
 249  * @clk: clock source
 250  * @rate: desired clock rate in Hz
 251  *
 252  * Returns rounded clock rate in Hz, or negative errno.
 253  */
 254 long clk_round_rate(struct clk *clk, unsigned long rate);
 255
 256 /**
 257  * clk_set_rate - set the clock rate for a clock source
 258  * @clk: clock source
 259  * @rate: desired clock rate in Hz
 260  *
 261  * Returns success (0) or negative errno.
 262  */
 263 int clk_set_rate(struct clk *clk, unsigned long rate);
 264
 265 /**
 266  * clk_set_parent - set the parent clock source for this clock
 267  * @clk: clock source
 268  * @parent: parent clock source
 269  *
 270  * Returns success (0) or negative errno.
 271  */
 272 int clk_set_parent(struct clk *clk, struct clk *parent);
 273
 274 /**
 275  * clk_get_parent - get the parent clock source for this clock
 276  * @clk: clock source
 277  *
 278  * Returns struct clk corresponding to parent clock source, or
 279  * valid IS_ERR() condition containing errno.
 280  */
 281 struct clk *clk_get_parent(struct clk *clk);
 282
 283 /**
 284  * clk_get_sys - get a clock based upon the device name
 285  * @dev_id: device name
 286  * @con_id: connection ID
 287  *
 288  * Returns a struct clk corresponding to the clock producer, or
 289  * valid IS_ERR() condition containing errno.  The implementation
 290  * uses @dev_id and @con_id to determine the clock consumer, and
 291  * thereby the clock producer. In contrast to clk_get() this function
 292  * takes the device name instead of the device itself for identification.
 293  *
 294  * Drivers must assume that the clock source is not enabled.
 295  *
 296  * clk_get_sys should not be called from within interrupt context.
 297  */
 298 struct clk *clk_get_sys(const char *dev_id, const char *con_id);
 299
 300 /**
 301  * clk_add_alias - add a new clock alias
 302  * @alias: name for clock alias
 303  * @alias_dev_name: device name
 304  * @id: platform specific clock name
 305  * @dev: device
 306  *
 307  * Allows using generic clock names for drivers by adding a new alias.
 308  * Assumes clkdev, see clkdev.h for more info.
 309  */
 310 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 311                         struct device *dev);
 312
 313 struct device_node;
 314 struct of_phandle_args;
 315
 316 #ifdef CONFIG_OF
 317 struct clk *of_clk_get(struct device_node *np, int index);
 318 struct clk *of_clk_get_by_name(struct device_node *np, const char *name);
 319 struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec);
 320 #else
 321 static inline struct clk *of_clk_get(struct device_node *np, int index)
 322 {
 323         return NULL;
 324 }
 325 static inline struct clk *of_clk_get_by_name(struct device_node *np,
 326                                              const char *name)
 327 {
 328         return NULL;
 329 }
 330 #endif
 331
 332 #endif