linux/include/linux/clk.h
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   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
  19struct device;
  20
  21struct 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 or
  32 *     NOTIFY_STOP.
  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.
  38 *
  39 * POST_RATE_CHANGE - called after the clk rate change has successfully
  40 *     completed.  Callbacks must always return NOTIFY_DONE.
  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 */
  58struct 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 */
  75struct clk_notifier_data {
  76        struct clk              *clk;
  77        unsigned long           old_rate;
  78        unsigned long           new_rate;
  79};
  80
  81int clk_notifier_register(struct clk *clk, struct notifier_block *nb);
  82
  83int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb);
  84
  85#endif
  86
  87/**
  88 * clk_prepare - prepare a clock source
  89 * @clk: clock source
  90 *
  91 * This prepares the clock source for use.
  92 *
  93 * Must not be called from within atomic context.
  94 */
  95#ifdef CONFIG_HAVE_CLK_PREPARE
  96int clk_prepare(struct clk *clk);
  97#else
  98static inline int clk_prepare(struct clk *clk)
  99{
 100        might_sleep();
 101        return 0;
 102}
 103#endif
 104
 105/**
 106 * clk_unprepare - undo preparation of a clock source
 107 * @clk: clock source
 108 *
 109 * This undoes a previously prepared clock.  The caller must balance
 110 * the number of prepare and unprepare calls.
 111 *
 112 * Must not be called from within atomic context.
 113 */
 114#ifdef CONFIG_HAVE_CLK_PREPARE
 115void clk_unprepare(struct clk *clk);
 116#else
 117static inline void clk_unprepare(struct clk *clk)
 118{
 119        might_sleep();
 120}
 121#endif
 122
 123#ifdef CONFIG_HAVE_CLK
 124/**
 125 * clk_get - lookup and obtain a reference to a clock producer.
 126 * @dev: device for clock "consumer"
 127 * @id: clock consumer ID
 128 *
 129 * Returns a struct clk corresponding to the clock producer, or
 130 * valid IS_ERR() condition containing errno.  The implementation
 131 * uses @dev and @id to determine the clock consumer, and thereby
 132 * the clock producer.  (IOW, @id may be identical strings, but
 133 * clk_get may return different clock producers depending on @dev.)
 134 *
 135 * Drivers must assume that the clock source is not enabled.
 136 *
 137 * clk_get should not be called from within interrupt context.
 138 */
 139struct clk *clk_get(struct device *dev, const char *id);
 140
 141/**
 142 * devm_clk_get - lookup and obtain a managed 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 * devm_clk_get should not be called from within interrupt context.
 155 *
 156 * The clock will automatically be freed when the device is unbound
 157 * from the bus.
 158 */
 159struct clk *devm_clk_get(struct device *dev, const char *id);
 160
 161/**
 162 * clk_enable - inform the system when the clock source should be running.
 163 * @clk: clock source
 164 *
 165 * If the clock can not be enabled/disabled, this should return success.
 166 *
 167 * May be called from atomic contexts.
 168 *
 169 * Returns success (0) or negative errno.
 170 */
 171int clk_enable(struct clk *clk);
 172
 173/**
 174 * clk_disable - inform the system when the clock source is no longer required.
 175 * @clk: clock source
 176 *
 177 * Inform the system that a clock source is no longer required by
 178 * a driver and may be shut down.
 179 *
 180 * May be called from atomic contexts.
 181 *
 182 * Implementation detail: if the clock source is shared between
 183 * multiple drivers, clk_enable() calls must be balanced by the
 184 * same number of clk_disable() calls for the clock source to be
 185 * disabled.
 186 */
 187void clk_disable(struct clk *clk);
 188
 189/**
 190 * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
 191 *                This is only valid once the clock source has been enabled.
 192 * @clk: clock source
 193 */
 194unsigned long clk_get_rate(struct clk *clk);
 195
 196/**
 197 * clk_put      - "free" the clock source
 198 * @clk: clock source
 199 *
 200 * Note: drivers must ensure that all clk_enable calls made on this
 201 * clock source are balanced by clk_disable calls prior to calling
 202 * this function.
 203 *
 204 * clk_put should not be called from within interrupt context.
 205 */
 206void clk_put(struct clk *clk);
 207
 208/**
 209 * devm_clk_put - "free" a managed clock source
 210 * @dev: device used to acuqire the clock
 211 * @clk: clock source acquired with devm_clk_get()
 212 *
 213 * Note: drivers must ensure that all clk_enable calls made on this
 214 * clock source are balanced by clk_disable calls prior to calling
 215 * this function.
 216 *
 217 * clk_put should not be called from within interrupt context.
 218 */
 219void devm_clk_put(struct device *dev, struct clk *clk);
 220
 221/*
 222 * The remaining APIs are optional for machine class support.
 223 */
 224
 225
 226/**
 227 * clk_round_rate - adjust a rate to the exact rate a clock can provide
 228 * @clk: clock source
 229 * @rate: desired clock rate in Hz
 230 *
 231 * Returns rounded clock rate in Hz, or negative errno.
 232 */
 233long clk_round_rate(struct clk *clk, unsigned long rate);
 234
 235/**
 236 * clk_set_rate - set the clock rate for a clock source
 237 * @clk: clock source
 238 * @rate: desired clock rate in Hz
 239 *
 240 * Returns success (0) or negative errno.
 241 */
 242int clk_set_rate(struct clk *clk, unsigned long rate);
 243
 244/**
 245 * clk_set_parent - set the parent clock source for this clock
 246 * @clk: clock source
 247 * @parent: parent clock source
 248 *
 249 * Returns success (0) or negative errno.
 250 */
 251int clk_set_parent(struct clk *clk, struct clk *parent);
 252
 253/**
 254 * clk_get_parent - get the parent clock source for this clock
 255 * @clk: clock source
 256 *
 257 * Returns struct clk corresponding to parent clock source, or
 258 * valid IS_ERR() condition containing errno.
 259 */
 260struct clk *clk_get_parent(struct clk *clk);
 261
 262/**
 263 * clk_get_sys - get a clock based upon the device name
 264 * @dev_id: device name
 265 * @con_id: connection ID
 266 *
 267 * Returns a struct clk corresponding to the clock producer, or
 268 * valid IS_ERR() condition containing errno.  The implementation
 269 * uses @dev_id and @con_id to determine the clock consumer, and
 270 * thereby the clock producer. In contrast to clk_get() this function
 271 * takes the device name instead of the device itself for identification.
 272 *
 273 * Drivers must assume that the clock source is not enabled.
 274 *
 275 * clk_get_sys should not be called from within interrupt context.
 276 */
 277struct clk *clk_get_sys(const char *dev_id, const char *con_id);
 278
 279#else /* !CONFIG_HAVE_CLK */
 280
 281static inline struct clk *clk_get(struct device *dev, const char *id)
 282{
 283        return NULL;
 284}
 285
 286static inline struct clk *devm_clk_get(struct device *dev, const char *id)
 287{
 288        return NULL;
 289}
 290
 291static inline void clk_put(struct clk *clk) {}
 292
 293static inline void devm_clk_put(struct device *dev, struct clk *clk) {}
 294
 295static inline int clk_enable(struct clk *clk)
 296{
 297        return 0;
 298}
 299
 300static inline void clk_disable(struct clk *clk) {}
 301
 302static inline unsigned long clk_get_rate(struct clk *clk)
 303{
 304        return 0;
 305}
 306
 307static inline int clk_set_rate(struct clk *clk, unsigned long rate)
 308{
 309        return 0;
 310}
 311
 312static inline long clk_round_rate(struct clk *clk, unsigned long rate)
 313{
 314        return 0;
 315}
 316
 317static inline int clk_set_parent(struct clk *clk, struct clk *parent)
 318{
 319        return 0;
 320}
 321
 322static inline struct clk *clk_get_parent(struct clk *clk)
 323{
 324        return NULL;
 325}
 326
 327#endif
 328
 329/* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
 330static inline int clk_prepare_enable(struct clk *clk)
 331{
 332        int ret;
 333
 334        ret = clk_prepare(clk);
 335        if (ret)
 336                return ret;
 337        ret = clk_enable(clk);
 338        if (ret)
 339                clk_unprepare(clk);
 340
 341        return ret;
 342}
 343
 344/* clk_disable_unprepare helps cases using clk_disable in non-atomic context. */
 345static inline void clk_disable_unprepare(struct clk *clk)
 346{
 347        clk_disable(clk);
 348        clk_unprepare(clk);
 349}
 350
 351/**
 352 * clk_add_alias - add a new clock alias
 353 * @alias: name for clock alias
 354 * @alias_dev_name: device name
 355 * @id: platform specific clock name
 356 * @dev: device
 357 *
 358 * Allows using generic clock names for drivers by adding a new alias.
 359 * Assumes clkdev, see clkdev.h for more info.
 360 */
 361int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 362                        struct device *dev);
 363
 364struct device_node;
 365struct of_phandle_args;
 366
 367#if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
 368struct clk *of_clk_get(struct device_node *np, int index);
 369struct clk *of_clk_get_by_name(struct device_node *np, const char *name);
 370struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec);
 371#else
 372static inline struct clk *of_clk_get(struct device_node *np, int index)
 373{
 374        return ERR_PTR(-ENOENT);
 375}
 376static inline struct clk *of_clk_get_by_name(struct device_node *np,
 377                                             const char *name)
 378{
 379        return ERR_PTR(-ENOENT);
 380}
 381#endif
 382
 383#endif
 384
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