xref: /openbmc/linux/drivers/clk/clk-pwm.c (revision e72cdad5)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2014 Philipp Zabel, Pengutronix
4  *
5  * PWM (mis)used as clock output
6  */
7 #include <linux/clk-provider.h>
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/of.h>
11 #include <linux/platform_device.h>
12 #include <linux/pwm.h>
13 
14 struct clk_pwm {
15 	struct clk_hw hw;
16 	struct pwm_device *pwm;
17 	u32 fixed_rate;
18 };
19 
to_clk_pwm(struct clk_hw * hw)20 static inline struct clk_pwm *to_clk_pwm(struct clk_hw *hw)
21 {
22 	return container_of(hw, struct clk_pwm, hw);
23 }
24 
clk_pwm_prepare(struct clk_hw * hw)25 static int clk_pwm_prepare(struct clk_hw *hw)
26 {
27 	struct clk_pwm *clk_pwm = to_clk_pwm(hw);
28 
29 	return pwm_enable(clk_pwm->pwm);
30 }
31 
clk_pwm_unprepare(struct clk_hw * hw)32 static void clk_pwm_unprepare(struct clk_hw *hw)
33 {
34 	struct clk_pwm *clk_pwm = to_clk_pwm(hw);
35 
36 	pwm_disable(clk_pwm->pwm);
37 }
38 
clk_pwm_recalc_rate(struct clk_hw * hw,unsigned long parent_rate)39 static unsigned long clk_pwm_recalc_rate(struct clk_hw *hw,
40 					 unsigned long parent_rate)
41 {
42 	struct clk_pwm *clk_pwm = to_clk_pwm(hw);
43 
44 	return clk_pwm->fixed_rate;
45 }
46 
clk_pwm_get_duty_cycle(struct clk_hw * hw,struct clk_duty * duty)47 static int clk_pwm_get_duty_cycle(struct clk_hw *hw, struct clk_duty *duty)
48 {
49 	struct clk_pwm *clk_pwm = to_clk_pwm(hw);
50 	struct pwm_state state;
51 
52 	pwm_get_state(clk_pwm->pwm, &state);
53 
54 	duty->num = state.duty_cycle;
55 	duty->den = state.period;
56 
57 	return 0;
58 }
59 
60 static const struct clk_ops clk_pwm_ops = {
61 	.prepare = clk_pwm_prepare,
62 	.unprepare = clk_pwm_unprepare,
63 	.recalc_rate = clk_pwm_recalc_rate,
64 	.get_duty_cycle = clk_pwm_get_duty_cycle,
65 };
66 
clk_pwm_probe(struct platform_device * pdev)67 static int clk_pwm_probe(struct platform_device *pdev)
68 {
69 	struct device_node *node = pdev->dev.of_node;
70 	struct clk_init_data init;
71 	struct clk_pwm *clk_pwm;
72 	struct pwm_device *pwm;
73 	struct pwm_args pargs;
74 	const char *clk_name;
75 	int ret;
76 
77 	clk_pwm = devm_kzalloc(&pdev->dev, sizeof(*clk_pwm), GFP_KERNEL);
78 	if (!clk_pwm)
79 		return -ENOMEM;
80 
81 	pwm = devm_pwm_get(&pdev->dev, NULL);
82 	if (IS_ERR(pwm))
83 		return PTR_ERR(pwm);
84 
85 	pwm_get_args(pwm, &pargs);
86 	if (!pargs.period) {
87 		dev_err(&pdev->dev, "invalid PWM period\n");
88 		return -EINVAL;
89 	}
90 
91 	if (of_property_read_u32(node, "clock-frequency", &clk_pwm->fixed_rate))
92 		clk_pwm->fixed_rate = div64_u64(NSEC_PER_SEC, pargs.period);
93 
94 	if (!clk_pwm->fixed_rate) {
95 		dev_err(&pdev->dev, "fixed_rate cannot be zero\n");
96 		return -EINVAL;
97 	}
98 
99 	if (pargs.period != NSEC_PER_SEC / clk_pwm->fixed_rate &&
100 	    pargs.period != DIV_ROUND_UP(NSEC_PER_SEC, clk_pwm->fixed_rate)) {
101 		dev_err(&pdev->dev,
102 			"clock-frequency does not match PWM period\n");
103 		return -EINVAL;
104 	}
105 
106 	/*
107 	 * FIXME: pwm_apply_args() should be removed when switching to the
108 	 * atomic PWM API.
109 	 */
110 	pwm_apply_args(pwm);
111 	ret = pwm_config(pwm, (pargs.period + 1) >> 1, pargs.period);
112 	if (ret < 0)
113 		return ret;
114 
115 	clk_name = node->name;
116 	of_property_read_string(node, "clock-output-names", &clk_name);
117 
118 	init.name = clk_name;
119 	init.ops = &clk_pwm_ops;
120 	init.flags = 0;
121 	init.num_parents = 0;
122 
123 	clk_pwm->pwm = pwm;
124 	clk_pwm->hw.init = &init;
125 	ret = devm_clk_hw_register(&pdev->dev, &clk_pwm->hw);
126 	if (ret)
127 		return ret;
128 
129 	return of_clk_add_hw_provider(node, of_clk_hw_simple_get, &clk_pwm->hw);
130 }
131 
clk_pwm_remove(struct platform_device * pdev)132 static void clk_pwm_remove(struct platform_device *pdev)
133 {
134 	of_clk_del_provider(pdev->dev.of_node);
135 }
136 
137 static const struct of_device_id clk_pwm_dt_ids[] = {
138 	{ .compatible = "pwm-clock" },
139 	{ }
140 };
141 MODULE_DEVICE_TABLE(of, clk_pwm_dt_ids);
142 
143 static struct platform_driver clk_pwm_driver = {
144 	.probe = clk_pwm_probe,
145 	.remove_new = clk_pwm_remove,
146 	.driver = {
147 		.name = "pwm-clock",
148 		.of_match_table = clk_pwm_dt_ids,
149 	},
150 };
151 
152 module_platform_driver(clk_pwm_driver);
153 
154 MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
155 MODULE_DESCRIPTION("PWM clock driver");
156 MODULE_LICENSE("GPL");
157