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
14struct clk_pwm {
15	struct clk_hw hw;
16	struct pwm_device *pwm;
17	u32 fixed_rate;
18};
19
20static inline struct clk_pwm *to_clk_pwm(struct clk_hw *hw)
21{
22	return container_of(hw, struct clk_pwm, hw);
23}
24
25static 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
32static 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
39static 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
47static 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
60static 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
67static 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
132static void clk_pwm_remove(struct platform_device *pdev)
133{
134	of_clk_del_provider(pdev->dev.of_node);
135}
136
137static const struct of_device_id clk_pwm_dt_ids[] = {
138	{ .compatible = "pwm-clock" },
139	{ }
140};
141MODULE_DEVICE_TABLE(of, clk_pwm_dt_ids);
142
143static 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
152module_platform_driver(clk_pwm_driver);
153
154MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
155MODULE_DESCRIPTION("PWM clock driver");
156MODULE_LICENSE("GPL");
157