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 * clk_get should not be called from within interrupt context. 40 */ 41 struct clk *clk_get(struct device *dev, const char *id); 42 43 /** 44 * clk_enable - inform the system when the clock source should be running. 45 * @clk: clock source 46 * 47 * If the clock can not be enabled/disabled, this should return success. 48 * 49 * Returns success (0) or negative errno. 50 */ 51 int clk_enable(struct clk *clk); 52 53 /** 54 * clk_disable - inform the system when the clock source is no longer required. 55 * @clk: clock source 56 * 57 * Inform the system that a clock source is no longer required by 58 * a driver and may be shut down. 59 * 60 * Implementation detail: if the clock source is shared between 61 * multiple drivers, clk_enable() calls must be balanced by the 62 * same number of clk_disable() calls for the clock source to be 63 * disabled. 64 */ 65 void clk_disable(struct clk *clk); 66 67 /** 68 * clk_get_rate - obtain the current clock rate (in Hz) for a clock source. 69 * This is only valid once the clock source has been enabled. 70 * @clk: clock source 71 */ 72 unsigned long clk_get_rate(struct clk *clk); 73 74 /** 75 * clk_put - "free" the clock source 76 * @clk: clock source 77 * 78 * Note: drivers must ensure that all clk_enable calls made on this 79 * clock source are balanced by clk_disable calls prior to calling 80 * this function. 81 * 82 * clk_put should not be called from within interrupt context. 83 */ 84 void clk_put(struct clk *clk); 85 86 87 /* 88 * The remaining APIs are optional for machine class support. 89 */ 90 91 92 /** 93 * clk_round_rate - adjust a rate to the exact rate a clock can provide 94 * @clk: clock source 95 * @rate: desired clock rate in Hz 96 * 97 * Returns rounded clock rate in Hz, or negative errno. 98 */ 99 long clk_round_rate(struct clk *clk, unsigned long rate); 100 101 /** 102 * clk_set_rate - set the clock rate for a clock source 103 * @clk: clock source 104 * @rate: desired clock rate in Hz 105 * 106 * Returns success (0) or negative errno. 107 */ 108 int clk_set_rate(struct clk *clk, unsigned long rate); 109 110 /** 111 * clk_set_parent - set the parent clock source for this clock 112 * @clk: clock source 113 * @parent: parent clock source 114 * 115 * Returns success (0) or negative errno. 116 */ 117 int clk_set_parent(struct clk *clk, struct clk *parent); 118 119 /** 120 * clk_get_parent - get the parent clock source for this clock 121 * @clk: clock source 122 * 123 * Returns struct clk corresponding to parent clock source, or 124 * valid IS_ERR() condition containing errno. 125 */ 126 struct clk *clk_get_parent(struct clk *clk); 127 128 #endif 129