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e5a06dc5 BT |
1 | /* |
2 | * Copyright 2014 Bart Tanghe <bart.tanghe@thomasmore.be> | |
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 as published by | |
6 | * the Free Software Foundation; version 2. | |
7 | */ | |
8 | ||
9 | #include <linux/clk.h> | |
10 | #include <linux/err.h> | |
11 | #include <linux/io.h> | |
12 | #include <linux/module.h> | |
13 | #include <linux/of.h> | |
14 | #include <linux/platform_device.h> | |
15 | #include <linux/pwm.h> | |
16 | ||
17 | #define PWM_CONTROL 0x000 | |
18 | #define PWM_CONTROL_SHIFT(x) ((x) * 8) | |
19 | #define PWM_CONTROL_MASK 0xff | |
20 | #define PWM_MODE 0x80 /* set timer in PWM mode */ | |
21 | #define PWM_ENABLE (1 << 0) | |
22 | #define PWM_POLARITY (1 << 4) | |
23 | ||
24 | #define PERIOD(x) (((x) * 0x10) + 0x10) | |
25 | #define DUTY(x) (((x) * 0x10) + 0x14) | |
26 | ||
27 | #define MIN_PERIOD 108 /* 9.2 MHz max. PWM clock */ | |
28 | ||
29 | struct bcm2835_pwm { | |
30 | struct pwm_chip chip; | |
31 | struct device *dev; | |
32 | unsigned long scaler; | |
33 | void __iomem *base; | |
34 | struct clk *clk; | |
35 | }; | |
36 | ||
37 | static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip) | |
38 | { | |
39 | return container_of(chip, struct bcm2835_pwm, chip); | |
40 | } | |
41 | ||
42 | static int bcm2835_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) | |
43 | { | |
44 | struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); | |
45 | u32 value; | |
46 | ||
47 | value = readl(pc->base + PWM_CONTROL); | |
48 | value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm)); | |
49 | value |= (PWM_MODE << PWM_CONTROL_SHIFT(pwm->hwpwm)); | |
50 | writel(value, pc->base + PWM_CONTROL); | |
51 | ||
52 | return 0; | |
53 | } | |
54 | ||
55 | static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) | |
56 | { | |
57 | struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); | |
58 | u32 value; | |
59 | ||
60 | value = readl(pc->base + PWM_CONTROL); | |
61 | value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm)); | |
62 | writel(value, pc->base + PWM_CONTROL); | |
63 | } | |
64 | ||
65 | static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, | |
66 | int duty_ns, int period_ns) | |
67 | { | |
68 | struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); | |
69 | ||
70 | if (period_ns <= MIN_PERIOD) { | |
71 | dev_err(pc->dev, "period %d not supported, minimum %d\n", | |
72 | period_ns, MIN_PERIOD); | |
73 | return -EINVAL; | |
74 | } | |
75 | ||
76 | writel(duty_ns / pc->scaler, pc->base + DUTY(pwm->hwpwm)); | |
77 | writel(period_ns / pc->scaler, pc->base + PERIOD(pwm->hwpwm)); | |
78 | ||
79 | return 0; | |
80 | } | |
81 | ||
82 | static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) | |
83 | { | |
84 | struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); | |
85 | u32 value; | |
86 | ||
87 | value = readl(pc->base + PWM_CONTROL); | |
88 | value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm); | |
89 | writel(value, pc->base + PWM_CONTROL); | |
90 | ||
91 | return 0; | |
92 | } | |
93 | ||
94 | static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) | |
95 | { | |
96 | struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); | |
97 | u32 value; | |
98 | ||
99 | value = readl(pc->base + PWM_CONTROL); | |
100 | value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm)); | |
101 | writel(value, pc->base + PWM_CONTROL); | |
102 | } | |
103 | ||
104 | static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, | |
105 | enum pwm_polarity polarity) | |
106 | { | |
107 | struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); | |
108 | u32 value; | |
109 | ||
110 | value = readl(pc->base + PWM_CONTROL); | |
111 | ||
112 | if (polarity == PWM_POLARITY_NORMAL) | |
113 | value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm)); | |
114 | else | |
115 | value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm); | |
116 | ||
117 | writel(value, pc->base + PWM_CONTROL); | |
118 | ||
119 | return 0; | |
120 | } | |
121 | ||
122 | static const struct pwm_ops bcm2835_pwm_ops = { | |
123 | .request = bcm2835_pwm_request, | |
124 | .free = bcm2835_pwm_free, | |
125 | .config = bcm2835_pwm_config, | |
126 | .enable = bcm2835_pwm_enable, | |
127 | .disable = bcm2835_pwm_disable, | |
128 | .set_polarity = bcm2835_set_polarity, | |
129 | .owner = THIS_MODULE, | |
130 | }; | |
131 | ||
132 | static int bcm2835_pwm_probe(struct platform_device *pdev) | |
133 | { | |
134 | struct bcm2835_pwm *pc; | |
135 | struct resource *res; | |
136 | int ret; | |
137 | ||
138 | pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL); | |
139 | if (!pc) | |
140 | return -ENOMEM; | |
141 | ||
142 | pc->dev = &pdev->dev; | |
143 | ||
144 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
145 | pc->base = devm_ioremap_resource(&pdev->dev, res); | |
146 | if (IS_ERR(pc->base)) | |
147 | return PTR_ERR(pc->base); | |
148 | ||
149 | pc->clk = devm_clk_get(&pdev->dev, NULL); | |
150 | if (IS_ERR(pc->clk)) { | |
151 | dev_err(&pdev->dev, "clock not found: %ld\n", PTR_ERR(pc->clk)); | |
152 | return PTR_ERR(pc->clk); | |
153 | } | |
154 | ||
155 | ret = clk_prepare_enable(pc->clk); | |
156 | if (ret) | |
157 | return ret; | |
158 | ||
159 | pc->scaler = NSEC_PER_SEC / clk_get_rate(pc->clk); | |
160 | ||
161 | pc->chip.dev = &pdev->dev; | |
162 | pc->chip.ops = &bcm2835_pwm_ops; | |
163 | pc->chip.npwm = 2; | |
164 | ||
165 | platform_set_drvdata(pdev, pc); | |
166 | ||
167 | ret = pwmchip_add(&pc->chip); | |
168 | if (ret < 0) | |
169 | goto add_fail; | |
170 | ||
171 | return 0; | |
172 | ||
173 | add_fail: | |
174 | clk_disable_unprepare(pc->clk); | |
175 | return ret; | |
176 | } | |
177 | ||
178 | static int bcm2835_pwm_remove(struct platform_device *pdev) | |
179 | { | |
180 | struct bcm2835_pwm *pc = platform_get_drvdata(pdev); | |
181 | ||
182 | clk_disable_unprepare(pc->clk); | |
183 | ||
184 | return pwmchip_remove(&pc->chip); | |
185 | } | |
186 | ||
187 | static const struct of_device_id bcm2835_pwm_of_match[] = { | |
188 | { .compatible = "brcm,bcm2835-pwm", }, | |
189 | { /* sentinel */ } | |
190 | }; | |
191 | MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match); | |
192 | ||
193 | static struct platform_driver bcm2835_pwm_driver = { | |
194 | .driver = { | |
195 | .name = "bcm2835-pwm", | |
196 | .of_match_table = bcm2835_pwm_of_match, | |
197 | }, | |
198 | .probe = bcm2835_pwm_probe, | |
199 | .remove = bcm2835_pwm_remove, | |
200 | }; | |
201 | module_platform_driver(bcm2835_pwm_driver); | |
202 | ||
203 | MODULE_AUTHOR("Bart Tanghe <bart.tanghe@thomasmore.be"); | |
204 | MODULE_DESCRIPTION("Broadcom BCM2835 PWM driver"); | |
205 | MODULE_LICENSE("GPL v2"); |