Root/drivers/clk/clk-fixed-rate.c

1/*
2 * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
3 * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 *
9 * Fixed rate clock implementation
10 */
11
12#include <linux/clk-provider.h>
13#include <linux/module.h>
14#include <linux/slab.h>
15#include <linux/io.h>
16#include <linux/err.h>
17#include <linux/of.h>
18
19/*
20 * DOC: basic fixed-rate clock that cannot gate
21 *
22 * Traits of this clock:
23 * prepare - clk_(un)prepare only ensures parents are prepared
24 * enable - clk_enable only ensures parents are enabled
25 * rate - rate is always a fixed value. No clk_set_rate support
26 * parent - fixed parent. No clk_set_parent support
27 */
28
29#define to_clk_fixed_rate(_hw) container_of(_hw, struct clk_fixed_rate, hw)
30
31static unsigned long clk_fixed_rate_recalc_rate(struct clk_hw *hw,
32        unsigned long parent_rate)
33{
34    return to_clk_fixed_rate(hw)->fixed_rate;
35}
36
37const struct clk_ops clk_fixed_rate_ops = {
38    .recalc_rate = clk_fixed_rate_recalc_rate,
39};
40EXPORT_SYMBOL_GPL(clk_fixed_rate_ops);
41
42/**
43 * clk_register_fixed_rate - register fixed-rate clock with the clock framework
44 * @dev: device that is registering this clock
45 * @name: name of this clock
46 * @parent_name: name of clock's parent
47 * @flags: framework-specific flags
48 * @fixed_rate: non-adjustable clock rate
49 */
50struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
51        const char *parent_name, unsigned long flags,
52        unsigned long fixed_rate)
53{
54    struct clk_fixed_rate *fixed;
55    struct clk *clk;
56    struct clk_init_data init;
57
58    /* allocate fixed-rate clock */
59    fixed = kzalloc(sizeof(struct clk_fixed_rate), GFP_KERNEL);
60    if (!fixed) {
61        pr_err("%s: could not allocate fixed clk\n", __func__);
62        return ERR_PTR(-ENOMEM);
63    }
64
65    init.name = name;
66    init.ops = &clk_fixed_rate_ops;
67    init.flags = flags | CLK_IS_BASIC;
68    init.parent_names = (parent_name ? &parent_name: NULL);
69    init.num_parents = (parent_name ? 1 : 0);
70
71    /* struct clk_fixed_rate assignments */
72    fixed->fixed_rate = fixed_rate;
73    fixed->hw.init = &init;
74
75    /* register the clock */
76    clk = clk_register(dev, &fixed->hw);
77
78    if (IS_ERR(clk))
79        kfree(fixed);
80
81    return clk;
82}
83
84#ifdef CONFIG_OF
85/**
86 * of_fixed_clk_setup() - Setup function for simple fixed rate clock
87 */
88void __init of_fixed_clk_setup(struct device_node *node)
89{
90    struct clk *clk;
91    const char *clk_name = node->name;
92    u32 rate;
93
94    if (of_property_read_u32(node, "clock-frequency", &rate))
95        return;
96
97    of_property_read_string(node, "clock-output-names", &clk_name);
98
99    clk = clk_register_fixed_rate(NULL, clk_name, NULL, CLK_IS_ROOT, rate);
100    if (clk)
101        of_clk_add_provider(node, of_clk_src_simple_get, clk);
102}
103EXPORT_SYMBOL_GPL(of_fixed_clk_setup);
104#endif
105

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