GNU Linux-libre 4.4.289-gnu1
[releases.git] / drivers / clk / clk-pwm.c
1 /*
2  * Copyright (C) 2014 Philipp Zabel, Pengutronix
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  *
8  * PWM (mis)used as clock output
9  */
10 #include <linux/clk-provider.h>
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/of.h>
14 #include <linux/platform_device.h>
15 #include <linux/pwm.h>
16
17 struct clk_pwm {
18         struct clk_hw hw;
19         struct pwm_device *pwm;
20         u32 fixed_rate;
21 };
22
23 static inline struct clk_pwm *to_clk_pwm(struct clk_hw *hw)
24 {
25         return container_of(hw, struct clk_pwm, hw);
26 }
27
28 static int clk_pwm_prepare(struct clk_hw *hw)
29 {
30         struct clk_pwm *clk_pwm = to_clk_pwm(hw);
31
32         return pwm_enable(clk_pwm->pwm);
33 }
34
35 static void clk_pwm_unprepare(struct clk_hw *hw)
36 {
37         struct clk_pwm *clk_pwm = to_clk_pwm(hw);
38
39         pwm_disable(clk_pwm->pwm);
40 }
41
42 static unsigned long clk_pwm_recalc_rate(struct clk_hw *hw,
43                                          unsigned long parent_rate)
44 {
45         struct clk_pwm *clk_pwm = to_clk_pwm(hw);
46
47         return clk_pwm->fixed_rate;
48 }
49
50 static const struct clk_ops clk_pwm_ops = {
51         .prepare = clk_pwm_prepare,
52         .unprepare = clk_pwm_unprepare,
53         .recalc_rate = clk_pwm_recalc_rate,
54 };
55
56 static int clk_pwm_probe(struct platform_device *pdev)
57 {
58         struct device_node *node = pdev->dev.of_node;
59         struct clk_init_data init;
60         struct clk_pwm *clk_pwm;
61         struct pwm_device *pwm;
62         const char *clk_name;
63         struct clk *clk;
64         int ret;
65
66         clk_pwm = devm_kzalloc(&pdev->dev, sizeof(*clk_pwm), GFP_KERNEL);
67         if (!clk_pwm)
68                 return -ENOMEM;
69
70         pwm = devm_pwm_get(&pdev->dev, NULL);
71         if (IS_ERR(pwm))
72                 return PTR_ERR(pwm);
73
74         if (!pwm->period) {
75                 dev_err(&pdev->dev, "invalid PWM period\n");
76                 return -EINVAL;
77         }
78
79         if (of_property_read_u32(node, "clock-frequency", &clk_pwm->fixed_rate))
80                 clk_pwm->fixed_rate = NSEC_PER_SEC / pwm->period;
81
82         if (pwm->period != NSEC_PER_SEC / clk_pwm->fixed_rate &&
83             pwm->period != DIV_ROUND_UP(NSEC_PER_SEC, clk_pwm->fixed_rate)) {
84                 dev_err(&pdev->dev,
85                         "clock-frequency does not match PWM period\n");
86                 return -EINVAL;
87         }
88
89         ret = pwm_config(pwm, (pwm->period + 1) >> 1, pwm->period);
90         if (ret < 0)
91                 return ret;
92
93         clk_name = node->name;
94         of_property_read_string(node, "clock-output-names", &clk_name);
95
96         init.name = clk_name;
97         init.ops = &clk_pwm_ops;
98         init.flags = CLK_IS_BASIC | CLK_IS_ROOT;
99         init.num_parents = 0;
100
101         clk_pwm->pwm = pwm;
102         clk_pwm->hw.init = &init;
103         clk = devm_clk_register(&pdev->dev, &clk_pwm->hw);
104         if (IS_ERR(clk))
105                 return PTR_ERR(clk);
106
107         return of_clk_add_provider(node, of_clk_src_simple_get, clk);
108 }
109
110 static int clk_pwm_remove(struct platform_device *pdev)
111 {
112         of_clk_del_provider(pdev->dev.of_node);
113
114         return 0;
115 }
116
117 static const struct of_device_id clk_pwm_dt_ids[] = {
118         { .compatible = "pwm-clock" },
119         { }
120 };
121 MODULE_DEVICE_TABLE(of, clk_pwm_dt_ids);
122
123 static struct platform_driver clk_pwm_driver = {
124         .probe = clk_pwm_probe,
125         .remove = clk_pwm_remove,
126         .driver = {
127                 .name = "pwm-clock",
128                 .of_match_table = of_match_ptr(clk_pwm_dt_ids),
129         },
130 };
131
132 module_platform_driver(clk_pwm_driver);
133
134 MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
135 MODULE_DESCRIPTION("PWM clock driver");
136 MODULE_LICENSE("GPL");