1 /* 2 * linux/include/linux/clk.h 3 * 4 * Copyright (C) 2004 ARM Limited. 5 * Written by Deep Blue Solutions Limited. 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 */ 11 #ifndef __LINUX_CLK_H 12 #define __LINUX_CLK_H 13 14 #include <linux/kernel.h> 15 16 struct device; 17 18 /* 19 * The base API. 20 */ 21 22 23 /* 24 * struct clk - an machine class defined object / cookie. 25 */ 26 struct clk; 27 28 /** 29 * clk_get - lookup and obtain a reference to a clock producer. 30 * @dev: device for clock "consumer" 31 * @id: clock comsumer ID 32 * 33 * Returns a struct clk corresponding to the clock producer, or 34 * valid IS_ERR() condition containing errno. The implementation 35 * uses @dev and @id to determine the clock consumer, and thereby 36 * the clock producer. (IOW, @id may be identical strings, but 37 * clk_get may return different clock producers depending on @dev.) 38 * 39 * Drivers must assume that the clock source is not enabled. 40 * 41 * clk_get should not be called from within interrupt context. 42 */ 43 struct clk *clk_get(struct device *dev, const char *id); 44 45 /** 46 * clk_prepare - prepare a clock source 47 * @clk: clock source 48 * 49 * This prepares the clock source for use. 50 * 51 * Must not be called from within atomic context. 52 */ 53 #ifdef CONFIG_HAVE_CLK_PREPARE 54 int clk_prepare(struct clk *clk); 55 #else 56 static inline int clk_prepare(struct clk *clk) 57 { 58 might_sleep(); 59 return 0; 60 } 61 #endif 62 63 /** 64 * clk_enable - inform the system when the clock source should be running. 65 * @clk: clock source 66 * 67 * If the clock can not be enabled/disabled, this should return success. 68 * 69 * May be called from atomic contexts. 70 * 71 * Returns success (0) or negative errno. 72 */ 73 int clk_enable(struct clk *clk); 74 75 /** 76 * clk_disable - inform the system when the clock source is no longer required. 77 * @clk: clock source 78 * 79 * Inform the system that a clock source is no longer required by 80 * a driver and may be shut down. 81 * 82 * May be called from atomic contexts. 83 * 84 * Implementation detail: if the clock source is shared between 85 * multiple drivers, clk_enable() calls must be balanced by the 86 * same number of clk_disable() calls for the clock source to be 87 * disabled. 88 */ 89 void clk_disable(struct clk *clk); 90 91 92 /** 93 * clk_unprepare - undo preparation of a clock source 94 * @clk: clock source 95 * 96 * This undoes a previously prepared clock. The caller must balance 97 * the number of prepare and unprepare calls. 98 * 99 * Must not be called from within atomic context. 100 */ 101 #ifdef CONFIG_HAVE_CLK_PREPARE 102 void clk_unprepare(struct clk *clk); 103 #else 104 static inline void clk_unprepare(struct clk *clk) 105 { 106 might_sleep(); 107 } 108 #endif 109 110 /** 111 * clk_get_rate - obtain the current clock rate (in Hz) for a clock source. 112 * This is only valid once the clock source has been enabled. 113 * @clk: clock source 114 */ 115 unsigned long clk_get_rate(struct clk *clk); 116 117 /** 118 * clk_put - "free" the clock source 119 * @clk: clock source 120 * 121 * Note: drivers must ensure that all clk_enable calls made on this 122 * clock source are balanced by clk_disable calls prior to calling 123 * this function. 124 * 125 * clk_put should not be called from within interrupt context. 126 */ 127 void clk_put(struct clk *clk); 128 129 130 /* 131 * The remaining APIs are optional for machine class support. 132 */ 133 134 135 /** 136 * clk_round_rate - adjust a rate to the exact rate a clock can provide 137 * @clk: clock source 138 * @rate: desired clock rate in Hz 139 * 140 * Returns rounded clock rate in Hz, or negative errno. 141 */ 142 long clk_round_rate(struct clk *clk, unsigned long rate); 143 144 /** 145 * clk_set_rate - set the clock rate for a clock source 146 * @clk: clock source 147 * @rate: desired clock rate in Hz 148 * 149 * Returns success (0) or negative errno. 150 */ 151 int clk_set_rate(struct clk *clk, unsigned long rate); 152 153 /** 154 * clk_set_parent - set the parent clock source for this clock 155 * @clk: clock source 156 * @parent: parent clock source 157 * 158 * Returns success (0) or negative errno. 159 */ 160 int clk_set_parent(struct clk *clk, struct clk *parent); 161 162 /** 163 * clk_get_parent - get the parent clock source for this clock 164 * @clk: clock source 165 * 166 * Returns struct clk corresponding to parent clock source, or 167 * valid IS_ERR() condition containing errno. 168 */ 169 struct clk *clk_get_parent(struct clk *clk); 170 171 /** 172 * clk_get_sys - get a clock based upon the device name 173 * @dev_id: device name 174 * @con_id: connection ID 175 * 176 * Returns a struct clk corresponding to the clock producer, or 177 * valid IS_ERR() condition containing errno. The implementation 178 * uses @dev_id and @con_id to determine the clock consumer, and 179 * thereby the clock producer. In contrast to clk_get() this function 180 * takes the device name instead of the device itself for identification. 181 * 182 * Drivers must assume that the clock source is not enabled. 183 * 184 * clk_get_sys should not be called from within interrupt context. 185 */ 186 struct clk *clk_get_sys(const char *dev_id, const char *con_id); 187 188 /** 189 * clk_add_alias - add a new clock alias 190 * @alias: name for clock alias 191 * @alias_dev_name: device name 192 * @id: platform specific clock name 193 * @dev: device 194 * 195 * Allows using generic clock names for drivers by adding a new alias. 196 * Assumes clkdev, see clkdev.h for more info. 197 */ 198 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id, 199 struct device *dev); 200 201 #endif 202