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9a74ccdb PZ |
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; | |
dd0b38b7 | 62 | struct pwm_args pargs; |
9a74ccdb | 63 | const char *clk_name; |
9a74ccdb PZ |
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 | ||
dd0b38b7 BB |
74 | pwm_get_args(pwm, &pargs); |
75 | if (!pargs.period) { | |
9a74ccdb PZ |
76 | dev_err(&pdev->dev, "invalid PWM period\n"); |
77 | return -EINVAL; | |
78 | } | |
79 | ||
80 | if (of_property_read_u32(node, "clock-frequency", &clk_pwm->fixed_rate)) | |
dd0b38b7 | 81 | clk_pwm->fixed_rate = NSEC_PER_SEC / pargs.period; |
9a74ccdb | 82 | |
dd0b38b7 BB |
83 | if (pargs.period != NSEC_PER_SEC / clk_pwm->fixed_rate && |
84 | pargs.period != DIV_ROUND_UP(NSEC_PER_SEC, clk_pwm->fixed_rate)) { | |
9a74ccdb PZ |
85 | dev_err(&pdev->dev, |
86 | "clock-frequency does not match PWM period\n"); | |
87 | return -EINVAL; | |
88 | } | |
89 | ||
dd0b38b7 BB |
90 | /* |
91 | * FIXME: pwm_apply_args() should be removed when switching to the | |
92 | * atomic PWM API. | |
93 | */ | |
94 | pwm_apply_args(pwm); | |
95 | ret = pwm_config(pwm, (pargs.period + 1) >> 1, pargs.period); | |
9a74ccdb PZ |
96 | if (ret < 0) |
97 | return ret; | |
98 | ||
99 | clk_name = node->name; | |
100 | of_property_read_string(node, "clock-output-names", &clk_name); | |
101 | ||
102 | init.name = clk_name; | |
103 | init.ops = &clk_pwm_ops; | |
1edfc1e7 | 104 | init.flags = CLK_IS_BASIC; |
9a74ccdb PZ |
105 | init.num_parents = 0; |
106 | ||
107 | clk_pwm->pwm = pwm; | |
108 | clk_pwm->hw.init = &init; | |
4cf915df SB |
109 | ret = devm_clk_hw_register(&pdev->dev, &clk_pwm->hw); |
110 | if (ret) | |
111 | return ret; | |
9a74ccdb | 112 | |
4cf915df | 113 | return of_clk_add_hw_provider(node, of_clk_hw_simple_get, &clk_pwm->hw); |
9a74ccdb PZ |
114 | } |
115 | ||
116 | static int clk_pwm_remove(struct platform_device *pdev) | |
117 | { | |
118 | of_clk_del_provider(pdev->dev.of_node); | |
119 | ||
120 | return 0; | |
121 | } | |
122 | ||
123 | static const struct of_device_id clk_pwm_dt_ids[] = { | |
124 | { .compatible = "pwm-clock" }, | |
125 | { } | |
126 | }; | |
127 | MODULE_DEVICE_TABLE(of, clk_pwm_dt_ids); | |
128 | ||
129 | static struct platform_driver clk_pwm_driver = { | |
130 | .probe = clk_pwm_probe, | |
131 | .remove = clk_pwm_remove, | |
132 | .driver = { | |
133 | .name = "pwm-clock", | |
134 | .of_match_table = of_match_ptr(clk_pwm_dt_ids), | |
135 | }, | |
136 | }; | |
137 | ||
138 | module_platform_driver(clk_pwm_driver); | |
139 | ||
140 | MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>"); | |
141 | MODULE_DESCRIPTION("PWM clock driver"); | |
142 | MODULE_LICENSE("GPL"); |