aboutsummaryrefslogtreecommitdiff
path: root/drivers/clk/clk-fixed-rate.c
blob: 321d3bbebe62b03a7d9451272ebec78a9a8c3a56 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
/*
 * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
 * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Fixed rate clock implementation
 */

#include <linux/clk-provider.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/err.h>
#include <linux/of.h>
#include <linux/platform_device.h>

/*
 * DOC: basic fixed-rate clock that cannot gate
 *
 * Traits of this clock:
 * prepare - clk_(un)prepare only ensures parents are prepared
 * enable - clk_enable only ensures parents are enabled
 * rate - rate is always a fixed value.  No clk_set_rate support
 * parent - fixed parent.  No clk_set_parent support
 */

#define to_clk_fixed_rate(_hw) container_of(_hw, struct clk_fixed_rate, hw)

static unsigned long clk_fixed_rate_recalc_rate(struct clk_hw *hw,
		unsigned long parent_rate)
{
	return to_clk_fixed_rate(hw)->fixed_rate;
}

static unsigned long clk_fixed_rate_recalc_accuracy(struct clk_hw *hw,
		unsigned long parent_accuracy)
{
	return to_clk_fixed_rate(hw)->fixed_accuracy;
}

const struct clk_ops clk_fixed_rate_ops = {
	.recalc_rate = clk_fixed_rate_recalc_rate,
	.recalc_accuracy = clk_fixed_rate_recalc_accuracy,
};
EXPORT_SYMBOL_GPL(clk_fixed_rate_ops);

/**
 * clk_register_fixed_rate_with_accuracy - register fixed-rate clock with the
 *					   clock framework
 * @dev: device that is registering this clock
 * @name: name of this clock
 * @parent_name: name of clock's parent
 * @flags: framework-specific flags
 * @fixed_rate: non-adjustable clock rate
 * @fixed_accuracy: non-adjustable clock rate
 */
struct clk *clk_register_fixed_rate_with_accuracy(struct device *dev,
		const char *name, const char *parent_name, unsigned long flags,
		unsigned long fixed_rate, unsigned long fixed_accuracy)
{
	struct clk_fixed_rate *fixed;
	struct clk *clk;
	struct clk_init_data init;

	/* allocate fixed-rate clock */
	fixed = kzalloc(sizeof(struct clk_fixed_rate), GFP_KERNEL);
	if (!fixed) {
		pr_err("%s: could not allocate fixed clk\n", __func__);
		return ERR_PTR(-ENOMEM);
	}

	init.name = name;
	init.ops = &clk_fixed_rate_ops;
	init.flags = flags | CLK_IS_BASIC;
	init.parent_names = (parent_name ? &parent_name: NULL);
	init.num_parents = (parent_name ? 1 : 0);

	/* struct clk_fixed_rate assignments */
	fixed->fixed_rate = fixed_rate;
	fixed->fixed_accuracy = fixed_accuracy;
	fixed->hw.init = &init;

	/* register the clock */
	clk = clk_register(dev, &fixed->hw);
	if (IS_ERR(clk))
		kfree(fixed);

	return clk;
}
EXPORT_SYMBOL_GPL(clk_register_fixed_rate_with_accuracy);

/**
 * clk_register_fixed_rate - register fixed-rate clock with the clock framework
 * @dev: device that is registering this clock
 * @name: name of this clock
 * @parent_name: name of clock's parent
 * @flags: framework-specific flags
 * @fixed_rate: non-adjustable clock rate
 */
struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
		const char *parent_name, unsigned long flags,
		unsigned long fixed_rate)
{
	return clk_register_fixed_rate_with_accuracy(dev, name, parent_name,
						     flags, fixed_rate, 0);
}
EXPORT_SYMBOL_GPL(clk_register_fixed_rate);

#ifdef CONFIG_OF
/**
 * of_fixed_clk_setup() - Setup function for simple fixed rate clock
 */
void of_fixed_clk_setup(struct device_node *node)
{
	struct clk *clk;
	const char *clk_name = node->name;
	u32 rate;
	u32 accuracy = 0;

	if (of_property_read_u32(node, "clock-frequency", &rate))
		return;

	of_property_read_u32(node, "clock-accuracy", &accuracy);

	of_property_read_string(node, "clock-output-names", &clk_name);

	clk = clk_register_fixed_rate_with_accuracy(NULL, clk_name, NULL,
						    CLK_IS_ROOT, rate,
						    accuracy);
	if (!IS_ERR(clk))
		of_clk_add_provider(node, of_clk_src_simple_get, clk);
}
EXPORT_SYMBOL_GPL(of_fixed_clk_setup);
#endif

static int fixed_clk_probe(struct platform_device *pdev)
{
	if (pdev->dev.of_node)
		of_fixed_clk_setup(pdev->dev.of_node);
	else
		return -ENODEV;

	return 0;
}

static const struct of_device_id fixed_clk_match[] = {
	{ .compatible = "fixed-clock" },
	{}
};

static struct platform_driver fixed_clk_driver = {
	.driver = {
		.name = "fixed-clk",
		.owner = THIS_MODULE,
		.of_match_table = fixed_clk_match,
	},
	.probe	= fixed_clk_probe,
};

static int __init fixed_clk_init(void)
{
	return platform_driver_register(&fixed_clk_driver);
}

/**
 * fixed clock will used for AMBA bus, UART and etc, so it should be
 * initialized early enough.
 */
postcore_initcall(fixed_clk_init);