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
14struct device;
15
16/*
17 * The base API.
18 */
19
20
21/*
22 * struct clk - an machine class defined object / cookie.
23 */
24struct 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 */
39struct 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 */
49int 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 */
63void 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 */
70unsigned 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 */
80void 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 */
95long 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 */
104int 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 */
113int 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 */
122struct clk *clk_get_parent(struct clk *clk);
123
124#endif
125