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