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/err.h>
  16 #include <linux/kernel.h>
  17 #include <linux/notifier.h>
  18
  19 struct device;
  20
  21 struct clk;
  22
  23 #ifdef CONFIG_COMMON_CLK
  24
  25 /**
  26  * DOC: clk notifier callback types
  27  *
  28  * PRE_RATE_CHANGE - called immediately before the clk rate is changed,
  29  *     to indicate that the rate change will proceed.  Drivers must
  30  *     immediately terminate any operations that will be affected by the
  31  *     rate change.  Callbacks may either return NOTIFY_DONE, NOTIFY_OK,
  32  *     NOTIFY_STOP or NOTIFY_BAD.
  33  *
  34  * ABORT_RATE_CHANGE: called if the rate change failed for some reason
  35  *     after PRE_RATE_CHANGE.  In this case, all registered notifiers on
  36  *     the clk will be called with ABORT_RATE_CHANGE. Callbacks must
  37  *     always return NOTIFY_DONE or NOTIFY_OK.
  38  *
  39  * POST_RATE_CHANGE - called after the clk rate change has successfully
  40  *     completed.  Callbacks must always return NOTIFY_DONE or NOTIFY_OK.
  41  *
  42  */
  43 #define PRE_RATE_CHANGE                 BIT(0)
  44 #define POST_RATE_CHANGE                BIT(1)
  45 #define ABORT_RATE_CHANGE               BIT(2)
  46
  47 /**
  48  * struct clk_notifier - associate a clk with a notifier
  49  * @clk: struct clk * to associate the notifier with
  50  * @notifier_head: a blocking_notifier_head for this clk
  51  * @node: linked list pointers
  52  *
  53  * A list of struct clk_notifier is maintained by the notifier code.
  54  * An entry is created whenever code registers the first notifier on a
  55  * particular @clk.  Future notifiers on that @clk are added to the
  56  * @notifier_head.
  57  */
  58 struct clk_notifier {
  59         struct clk                      *clk;
  60         struct srcu_notifier_head       notifier_head;
  61         struct list_head                node;
  62 };
  63
  64 /**
  65  * struct clk_notifier_data - rate data to pass to the notifier callback
  66  * @clk: struct clk * being changed
  67  * @old_rate: previous rate of this clk
  68  * @new_rate: new rate of this clk
  69  *
  70  * For a pre-notifier, old_rate is the clk's rate before this rate
  71  * change, and new_rate is what the rate will be in the future.  For a
  72  * post-notifier, old_rate and new_rate are both set to the clk's
  73  * current rate (this was done to optimize the implementation).
  74  */
  75 struct clk_notifier_data {
  76         struct clk              *clk;
  77         unsigned long           old_rate;
  78         unsigned long           new_rate;
  79 };
  80
  81 int clk_notifier_register(struct clk *clk, struct notifier_block *nb);
  82
  83 int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb);
  84
  85 /**
  86  * clk_get_accuracy - obtain the clock accuracy in ppb (parts per billion)
  87  *                    for a clock source.
  88  * @clk: clock source
  89  *
  90  * This gets the clock source accuracy expressed in ppb.
  91  * A perfect clock returns 0.
  92  */
  93 long clk_get_accuracy(struct clk *clk);
  94
  95 #else
  96
  97 static inline long clk_get_accuracy(struct clk *clk)
  98 {
  99         return -ENOTSUPP;
 100 }
 101
 102 #endif
 103
 104 /**
 105  * clk_prepare - prepare a clock source
 106  * @clk: clock source
 107  *
 108  * This prepares the clock source for use.
 109  *
 110  * Must not be called from within atomic context.
 111  */
 112 #ifdef CONFIG_HAVE_CLK_PREPARE
 113 int clk_prepare(struct clk *clk);
 114 #else
 115 static inline int clk_prepare(struct clk *clk)
 116 {
 117         might_sleep();
 118         return 0;
 119 }
 120 #endif
 121
 122 /**
 123  * clk_unprepare - undo preparation of a clock source
 124  * @clk: clock source
 125  *
 126  * This undoes a previously prepared clock.  The caller must balance
 127  * the number of prepare and unprepare calls.
 128  *
 129  * Must not be called from within atomic context.
 130  */
 131 #ifdef CONFIG_HAVE_CLK_PREPARE
 132 void clk_unprepare(struct clk *clk);
 133 #else
 134 static inline void clk_unprepare(struct clk *clk)
 135 {
 136         might_sleep();
 137 }
 138 #endif
 139
 140 #ifdef CONFIG_HAVE_CLK
 141 /**
 142  * clk_get - lookup and obtain a reference to a clock producer.
 143  * @dev: device for clock "consumer"
 144  * @id: clock consumer ID
 145  *
 146  * Returns a struct clk corresponding to the clock producer, or
 147  * valid IS_ERR() condition containing errno.  The implementation
 148  * uses @dev and @id to determine the clock consumer, and thereby
 149  * the clock producer.  (IOW, @id may be identical strings, but
 150  * clk_get may return different clock producers depending on @dev.)
 151  *
 152  * Drivers must assume that the clock source is not enabled.
 153  *
 154  * clk_get should not be called from within interrupt context.
 155  */
 156 struct clk *clk_get(struct device *dev, const char *id);
 157
 158 /**
 159  * devm_clk_get - lookup and obtain a managed reference to a clock producer.
 160  * @dev: device for clock "consumer"
 161  * @id: clock consumer ID
 162  *
 163  * Returns a struct clk corresponding to the clock producer, or
 164  * valid IS_ERR() condition containing errno.  The implementation
 165  * uses @dev and @id to determine the clock consumer, and thereby
 166  * the clock producer.  (IOW, @id may be identical strings, but
 167  * clk_get may return different clock producers depending on @dev.)
 168  *
 169  * Drivers must assume that the clock source is not enabled.
 170  *
 171  * devm_clk_get should not be called from within interrupt context.
 172  *
 173  * The clock will automatically be freed when the device is unbound
 174  * from the bus.
 175  */
 176 struct clk *devm_clk_get(struct device *dev, const char *id);
 177
 178 /**
 179  * clk_enable - inform the system when the clock source should be running.
 180  * @clk: clock source
 181  *
 182  * If the clock can not be enabled/disabled, this should return success.
 183  *
 184  * May be called from atomic contexts.
 185  *
 186  * Returns success (0) or negative errno.
 187  */
 188 int clk_enable(struct clk *clk);
 189
 190 /**
 191  * clk_disable - inform the system when the clock source is no longer required.
 192  * @clk: clock source
 193  *
 194  * Inform the system that a clock source is no longer required by
 195  * a driver and may be shut down.
 196  *
 197  * May be called from atomic contexts.
 198  *
 199  * Implementation detail: if the clock source is shared between
 200  * multiple drivers, clk_enable() calls must be balanced by the
 201  * same number of clk_disable() calls for the clock source to be
 202  * disabled.
 203  */
 204 void clk_disable(struct clk *clk);
 205
 206 /**
 207  * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
 208  *                This is only valid once the clock source has been enabled.
 209  * @clk: clock source
 210  */
 211 unsigned long clk_get_rate(struct clk *clk);
 212
 213 /**
 214  * clk_put      - "free" the clock source
 215  * @clk: clock source
 216  *
 217  * Note: drivers must ensure that all clk_enable calls made on this
 218  * clock source are balanced by clk_disable calls prior to calling
 219  * this function.
 220  *
 221  * clk_put should not be called from within interrupt context.
 222  */
 223 void clk_put(struct clk *clk);
 224
 225 /**
 226  * devm_clk_put - "free" a managed clock source
 227  * @dev: device used to acuqire the clock
 228  * @clk: clock source acquired with devm_clk_get()
 229  *
 230  * Note: drivers must ensure that all clk_enable calls made on this
 231  * clock source are balanced by clk_disable calls prior to calling
 232  * this function.
 233  *
 234  * clk_put should not be called from within interrupt context.
 235  */
 236 void devm_clk_put(struct device *dev, struct clk *clk);
 237
 238 /*
 239  * The remaining APIs are optional for machine class support.
 240  */
 241
 242
 243 /**
 244  * clk_round_rate - adjust a rate to the exact rate a clock can provide
 245  * @clk: clock source
 246  * @rate: desired clock rate in Hz
 247  *
 248  * Returns rounded clock rate in Hz, or negative errno.
 249  */
 250 long clk_round_rate(struct clk *clk, unsigned long rate);
 251
 252 /**
 253  * clk_set_rate - set the clock rate for a clock source
 254  * @clk: clock source
 255  * @rate: desired clock rate in Hz
 256  *
 257  * Returns success (0) or negative errno.
 258  */
 259 int clk_set_rate(struct clk *clk, unsigned long rate);
 260
 261 /**
 262  * clk_set_parent - set the parent clock source for this clock
 263  * @clk: clock source
 264  * @parent: parent clock source
 265  *
 266  * Returns success (0) or negative errno.
 267  */
 268 int clk_set_parent(struct clk *clk, struct clk *parent);
 269
 270 /**
 271  * clk_get_parent - get the parent clock source for this clock
 272  * @clk: clock source
 273  *
 274  * Returns struct clk corresponding to parent clock source, or
 275  * valid IS_ERR() condition containing errno.
 276  */
 277 struct clk *clk_get_parent(struct clk *clk);
 278
 279 /**
 280  * clk_get_sys - get a clock based upon the device name
 281  * @dev_id: device name
 282  * @con_id: connection ID
 283  *
 284  * Returns a struct clk corresponding to the clock producer, or
 285  * valid IS_ERR() condition containing errno.  The implementation
 286  * uses @dev_id and @con_id to determine the clock consumer, and
 287  * thereby the clock producer. In contrast to clk_get() this function
 288  * takes the device name instead of the device itself for identification.
 289  *
 290  * Drivers must assume that the clock source is not enabled.
 291  *
 292  * clk_get_sys should not be called from within interrupt context.
 293  */
 294 struct clk *clk_get_sys(const char *dev_id, const char *con_id);
 295
 296 #else /* !CONFIG_HAVE_CLK */
 297
 298 static inline struct clk *clk_get(struct device *dev, const char *id)
 299 {
 300         return NULL;
 301 }
 302
 303 static inline struct clk *devm_clk_get(struct device *dev, const char *id)
 304 {
 305         return NULL;
 306 }
 307
 308 static inline void clk_put(struct clk *clk) {}
 309
 310 static inline void devm_clk_put(struct device *dev, struct clk *clk) {}
 311
 312 static inline int clk_enable(struct clk *clk)
 313 {
 314         return 0;
 315 }
 316
 317 static inline void clk_disable(struct clk *clk) {}
 318
 319 static inline unsigned long clk_get_rate(struct clk *clk)
 320 {
 321         return 0;
 322 }
 323
 324 static inline int clk_set_rate(struct clk *clk, unsigned long rate)
 325 {
 326         return 0;
 327 }
 328
 329 static inline long clk_round_rate(struct clk *clk, unsigned long rate)
 330 {
 331         return 0;
 332 }
 333
 334 static inline int clk_set_parent(struct clk *clk, struct clk *parent)
 335 {
 336         return 0;
 337 }
 338
 339 static inline struct clk *clk_get_parent(struct clk *clk)
 340 {
 341         return NULL;
 342 }
 343
 344 #endif
 345
 346 /* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
 347 static inline int clk_prepare_enable(struct clk *clk)
 348 {
 349         int ret;
 350
 351         ret = clk_prepare(clk);
 352         if (ret)
 353                 return ret;
 354         ret = clk_enable(clk);
 355         if (ret)
 356                 clk_unprepare(clk);
 357
 358         return ret;
 359 }
 360
 361 /* clk_disable_unprepare helps cases using clk_disable in non-atomic context. */
 362 static inline void clk_disable_unprepare(struct clk *clk)
 363 {
 364         clk_disable(clk);
 365         clk_unprepare(clk);
 366 }
 367
 368 /**
 369  * clk_add_alias - add a new clock alias
 370  * @alias: name for clock alias
 371  * @alias_dev_name: device name
 372  * @id: platform specific clock name
 373  * @dev: device
 374  *
 375  * Allows using generic clock names for drivers by adding a new alias.
 376  * Assumes clkdev, see clkdev.h for more info.
 377  */
 378 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 379                         struct device *dev);
 380
 381 struct device_node;
 382 struct of_phandle_args;
 383
 384 #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
 385 struct clk *of_clk_get(struct device_node *np, int index);
 386 struct clk *of_clk_get_by_name(struct device_node *np, const char *name);
 387 struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec);
 388 #else
 389 static inline struct clk *of_clk_get(struct device_node *np, int index)
 390 {
 391         return ERR_PTR(-ENOENT);
 392 }
 393 static inline struct clk *of_clk_get_by_name(struct device_node *np,
 394                                              const char *name)
 395 {
 396         return ERR_PTR(-ENOENT);
 397 }
 398 #endif
 399
 400 #endif