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 struct device; 15 16 /* 17 * The base API. 18 */ 19 20 21 /* 22 * struct clk - an machine class defined object / cookie. 23 */ 24 struct clk; 25 26 /** 27 * clk_get - lookup and obtain a reference to a clock producer. 28 * @dev: device for clock "consumer" 29 * @id: clock comsumer ID 30 * 31 * Returns a struct clk corresponding to the clock producer, or 32 * valid IS_ERR() condition containing errno. The implementation 33 * uses @dev and @id to determine the clock consumer, and thereby 34 * the clock producer. (IOW, @id may be identical strings, but 35 * clk_get may return different clock producers depending on @dev.) 36 * 37 * Drivers must assume that the clock source is not enabled. 38 */ 39 struct clk *clk_get(struct device *dev, const char *id); 40 41 /** 42 * clk_enable - inform the system when the clock source should be running. 43 * @clk: clock source 44 * 45 * If the clock can not be enabled/disabled, this should return success. 46 * 47 * Returns success (0) or negative errno. 48 */ 49 int clk_enable(struct clk *clk); 50 51 /** 52 * clk_disable - inform the system when the clock source is no longer required. 53 * @clk: clock source 54 * 55 * Inform the system that a clock source is no longer required by 56 * a driver and may be shut down. 57 * 58 * Implementation detail: if the clock source is shared between 59 * multiple drivers, clk_enable() calls must be balanced by the 60 * same number of clk_disable() calls for the clock source to be 61 * disabled. 62 */ 63 void clk_disable(struct clk *clk); 64 65 /** 66 * clk_get_rate - obtain the current clock rate (in Hz) for a clock source. 67 * This is only valid once the clock source has been enabled. 68 * @clk: clock source 69 */ 70 unsigned long clk_get_rate(struct clk *clk); 71 72 /** 73 * clk_put - "free" the clock source 74 * @clk: clock source 75 * 76 * Note: drivers must ensure that all clk_enable calls made on this 77 * clock source are balanced by clk_disable calls prior to calling 78 * this function. 79 */ 80 void clk_put(struct clk *clk); 81 82 83 /* 84 * The remaining APIs are optional for machine class support. 85 */ 86 87 88 /** 89 * clk_round_rate - adjust a rate to the exact rate a clock can provide 90 * @clk: clock source 91 * @rate: desired clock rate in Hz 92 * 93 * Returns rounded clock rate in Hz, or negative errno. 94 */ 95 long clk_round_rate(struct clk *clk, unsigned long rate); 96 97 /** 98 * clk_set_rate - set the clock rate for a clock source 99 * @clk: clock source 100 * @rate: desired clock rate in Hz 101 * 102 * Returns success (0) or negative errno. 103 */ 104 int clk_set_rate(struct clk *clk, unsigned long rate); 105 106 /** 107 * clk_set_parent - set the parent clock source for this clock 108 * @clk: clock source 109 * @parent: parent clock source 110 * 111 * Returns success (0) or negative errno. 112 */ 113 int clk_set_parent(struct clk *clk, struct clk *parent); 114 115 /** 116 * clk_get_parent - get the parent clock source for this clock 117 * @clk: clock source 118 * 119 * Returns struct clk corresponding to parent clock source, or 120 * valid IS_ERR() condition containing errno. 121 */ 122 struct clk *clk_get_parent(struct clk *clk); 123 124 #endif 125
