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
|
/*
* Copyright (C) 2014 Philipp Zabel, Pengutronix
*
* 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.
*
* PWM (mis)used as clock output
*/
#include <linux/clk-provider.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
struct clk_pwm {
struct clk_hw hw;
struct pwm_device *pwm;
u32 fixed_rate;
};
static inline struct clk_pwm *to_clk_pwm(struct clk_hw *hw)
{
return container_of(hw, struct clk_pwm, hw);
}
static int clk_pwm_prepare(struct clk_hw *hw)
{
struct clk_pwm *clk_pwm = to_clk_pwm(hw);
return pwm_enable(clk_pwm->pwm);
}
static void clk_pwm_unprepare(struct clk_hw *hw)
{
struct clk_pwm *clk_pwm = to_clk_pwm(hw);
pwm_disable(clk_pwm->pwm);
}
static unsigned long clk_pwm_recalc_rate(struct clk_hw *hw,
unsigned long parent_rate)
{
struct clk_pwm *clk_pwm = to_clk_pwm(hw);
return clk_pwm->fixed_rate;
}
static const struct clk_ops clk_pwm_ops = {
.prepare = clk_pwm_prepare,
.unprepare = clk_pwm_unprepare,
.recalc_rate = clk_pwm_recalc_rate,
};
static int clk_pwm_probe(struct platform_device *pdev)
{
struct device_node *node = pdev->dev.of_node;
struct clk_init_data init;
struct clk_pwm *clk_pwm;
struct pwm_device *pwm;
struct pwm_args pargs;
const char *clk_name;
int ret;
clk_pwm = devm_kzalloc(&pdev->dev, sizeof(*clk_pwm), GFP_KERNEL);
if (!clk_pwm)
return -ENOMEM;
pwm = devm_pwm_get(&pdev->dev, NULL);
if (IS_ERR(pwm))
return PTR_ERR(pwm);
pwm_get_args(pwm, &pargs);
if (!pargs.period) {
dev_err(&pdev->dev, "invalid PWM period\n");
return -EINVAL;
}
if (of_property_read_u32(node, "clock-frequency", &clk_pwm->fixed_rate))
clk_pwm->fixed_rate = NSEC_PER_SEC / pargs.period;
if (pargs.period != NSEC_PER_SEC / clk_pwm->fixed_rate &&
pargs.period != DIV_ROUND_UP(NSEC_PER_SEC, clk_pwm->fixed_rate)) {
dev_err(&pdev->dev,
"clock-frequency does not match PWM period\n");
return -EINVAL;
}
/*
* FIXME: pwm_apply_args() should be removed when switching to the
* atomic PWM API.
*/
pwm_apply_args(pwm);
ret = pwm_config(pwm, (pargs.period + 1) >> 1, pargs.period);
if (ret < 0)
return ret;
clk_name = node->name;
of_property_read_string(node, "clock-output-names", &clk_name);
init.name = clk_name;
init.ops = &clk_pwm_ops;
init.flags = CLK_IS_BASIC;
init.num_parents = 0;
clk_pwm->pwm = pwm;
clk_pwm->hw.init = &init;
ret = devm_clk_hw_register(&pdev->dev, &clk_pwm->hw);
if (ret)
return ret;
return of_clk_add_hw_provider(node, of_clk_hw_simple_get, &clk_pwm->hw);
}
static int clk_pwm_remove(struct platform_device *pdev)
{
of_clk_del_provider(pdev->dev.of_node);
return 0;
}
static const struct of_device_id clk_pwm_dt_ids[] = {
{ .compatible = "pwm-clock" },
{ }
};
MODULE_DEVICE_TABLE(of, clk_pwm_dt_ids);
static struct platform_driver clk_pwm_driver = {
.probe = clk_pwm_probe,
.remove = clk_pwm_remove,
.driver = {
.name = "pwm-clock",
.of_match_table = of_match_ptr(clk_pwm_dt_ids),
},
};
module_platform_driver(clk_pwm_driver);
MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
MODULE_DESCRIPTION("PWM clock driver");
MODULE_LICENSE("GPL");
|
