2 * Copyright (C) 2014 Philipp Zabel, Pengutronix
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.
8 * PWM (mis)used as clock output
10 #include <linux/clk-provider.h>
11 #include <linux/kernel.h>
12 #include <linux/module.h>
14 #include <linux/platform_device.h>
15 #include <linux/pwm.h>
19 struct pwm_device *pwm;
23 static inline struct clk_pwm *to_clk_pwm(struct clk_hw *hw)
25 return container_of(hw, struct clk_pwm, hw);
28 static int clk_pwm_prepare(struct clk_hw *hw)
30 struct clk_pwm *clk_pwm = to_clk_pwm(hw);
32 return pwm_enable(clk_pwm->pwm);
35 static void clk_pwm_unprepare(struct clk_hw *hw)
37 struct clk_pwm *clk_pwm = to_clk_pwm(hw);
39 pwm_disable(clk_pwm->pwm);
42 static unsigned long clk_pwm_recalc_rate(struct clk_hw *hw,
43 unsigned long parent_rate)
45 struct clk_pwm *clk_pwm = to_clk_pwm(hw);
47 return clk_pwm->fixed_rate;
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,
56 static int clk_pwm_probe(struct platform_device *pdev)
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;
66 clk_pwm = devm_kzalloc(&pdev->dev, sizeof(*clk_pwm), GFP_KERNEL);
70 pwm = devm_pwm_get(&pdev->dev, NULL);
75 dev_err(&pdev->dev, "invalid PWM period\n");
79 if (of_property_read_u32(node, "clock-frequency", &clk_pwm->fixed_rate))
80 clk_pwm->fixed_rate = NSEC_PER_SEC / pwm->period;
82 if (pwm->period != NSEC_PER_SEC / clk_pwm->fixed_rate &&
83 pwm->period != DIV_ROUND_UP(NSEC_PER_SEC, clk_pwm->fixed_rate)) {
85 "clock-frequency does not match PWM period\n");
89 ret = pwm_config(pwm, (pwm->period + 1) >> 1, pwm->period);
93 clk_name = node->name;
94 of_property_read_string(node, "clock-output-names", &clk_name);
97 init.ops = &clk_pwm_ops;
98 init.flags = CLK_IS_BASIC | CLK_IS_ROOT;
102 clk_pwm->hw.init = &init;
103 clk = devm_clk_register(&pdev->dev, &clk_pwm->hw);
107 return of_clk_add_provider(node, of_clk_src_simple_get, clk);
110 static int clk_pwm_remove(struct platform_device *pdev)
112 of_clk_del_provider(pdev->dev.of_node);
117 static const struct of_device_id clk_pwm_dt_ids[] = {
118 { .compatible = "pwm-clock" },
121 MODULE_DEVICE_TABLE(of, clk_pwm_dt_ids);
123 static struct platform_driver clk_pwm_driver = {
124 .probe = clk_pwm_probe,
125 .remove = clk_pwm_remove,
128 .of_match_table = of_match_ptr(clk_pwm_dt_ids),
132 module_platform_driver(clk_pwm_driver);
134 MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
135 MODULE_DESCRIPTION("PWM clock driver");
136 MODULE_LICENSE("GPL");