GNU Linux-libre 4.9.328-gnu1
[releases.git] / drivers / pwm / pwm-bcm2835.c
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         void __iomem *base;
33         struct clk *clk;
34 };
35
36 static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip)
37 {
38         return container_of(chip, struct bcm2835_pwm, chip);
39 }
40
41 static int bcm2835_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
42 {
43         struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
44         u32 value;
45
46         value = readl(pc->base + PWM_CONTROL);
47         value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
48         value |= (PWM_MODE << PWM_CONTROL_SHIFT(pwm->hwpwm));
49         writel(value, pc->base + PWM_CONTROL);
50
51         return 0;
52 }
53
54 static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
55 {
56         struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
57         u32 value;
58
59         value = readl(pc->base + PWM_CONTROL);
60         value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
61         writel(value, pc->base + PWM_CONTROL);
62 }
63
64 static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
65                               int duty_ns, int period_ns)
66 {
67         struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
68         unsigned long rate = clk_get_rate(pc->clk);
69         unsigned long scaler;
70
71         if (!rate) {
72                 dev_err(pc->dev, "failed to get clock rate\n");
73                 return -EINVAL;
74         }
75
76         scaler = NSEC_PER_SEC / rate;
77
78         if (period_ns <= MIN_PERIOD) {
79                 dev_err(pc->dev, "period %d not supported, minimum %d\n",
80                         period_ns, MIN_PERIOD);
81                 return -EINVAL;
82         }
83
84         writel(duty_ns / scaler, pc->base + DUTY(pwm->hwpwm));
85         writel(period_ns / scaler, pc->base + PERIOD(pwm->hwpwm));
86
87         return 0;
88 }
89
90 static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
91 {
92         struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
93         u32 value;
94
95         value = readl(pc->base + PWM_CONTROL);
96         value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
97         writel(value, pc->base + PWM_CONTROL);
98
99         return 0;
100 }
101
102 static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
103 {
104         struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
105         u32 value;
106
107         value = readl(pc->base + PWM_CONTROL);
108         value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
109         writel(value, pc->base + PWM_CONTROL);
110 }
111
112 static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
113                                 enum pwm_polarity polarity)
114 {
115         struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
116         u32 value;
117
118         value = readl(pc->base + PWM_CONTROL);
119
120         if (polarity == PWM_POLARITY_NORMAL)
121                 value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
122         else
123                 value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
124
125         writel(value, pc->base + PWM_CONTROL);
126
127         return 0;
128 }
129
130 static const struct pwm_ops bcm2835_pwm_ops = {
131         .request = bcm2835_pwm_request,
132         .free = bcm2835_pwm_free,
133         .config = bcm2835_pwm_config,
134         .enable = bcm2835_pwm_enable,
135         .disable = bcm2835_pwm_disable,
136         .set_polarity = bcm2835_set_polarity,
137         .owner = THIS_MODULE,
138 };
139
140 static int bcm2835_pwm_probe(struct platform_device *pdev)
141 {
142         struct bcm2835_pwm *pc;
143         struct resource *res;
144         int ret;
145
146         pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
147         if (!pc)
148                 return -ENOMEM;
149
150         pc->dev = &pdev->dev;
151
152         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
153         pc->base = devm_ioremap_resource(&pdev->dev, res);
154         if (IS_ERR(pc->base))
155                 return PTR_ERR(pc->base);
156
157         pc->clk = devm_clk_get(&pdev->dev, NULL);
158         if (IS_ERR(pc->clk)) {
159                 dev_err(&pdev->dev, "clock not found: %ld\n", PTR_ERR(pc->clk));
160                 return PTR_ERR(pc->clk);
161         }
162
163         ret = clk_prepare_enable(pc->clk);
164         if (ret)
165                 return ret;
166
167         pc->chip.dev = &pdev->dev;
168         pc->chip.ops = &bcm2835_pwm_ops;
169         pc->chip.base = -1;
170         pc->chip.npwm = 2;
171
172         platform_set_drvdata(pdev, pc);
173
174         ret = pwmchip_add(&pc->chip);
175         if (ret < 0)
176                 goto add_fail;
177
178         return 0;
179
180 add_fail:
181         clk_disable_unprepare(pc->clk);
182         return ret;
183 }
184
185 static int bcm2835_pwm_remove(struct platform_device *pdev)
186 {
187         struct bcm2835_pwm *pc = platform_get_drvdata(pdev);
188
189         clk_disable_unprepare(pc->clk);
190
191         return pwmchip_remove(&pc->chip);
192 }
193
194 static const struct of_device_id bcm2835_pwm_of_match[] = {
195         { .compatible = "brcm,bcm2835-pwm", },
196         { /* sentinel */ }
197 };
198 MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match);
199
200 static struct platform_driver bcm2835_pwm_driver = {
201         .driver = {
202                 .name = "bcm2835-pwm",
203                 .of_match_table = bcm2835_pwm_of_match,
204         },
205         .probe = bcm2835_pwm_probe,
206         .remove = bcm2835_pwm_remove,
207 };
208 module_platform_driver(bcm2835_pwm_driver);
209
210 MODULE_AUTHOR("Bart Tanghe <bart.tanghe@thomasmore.be>");
211 MODULE_DESCRIPTION("Broadcom BCM2835 PWM driver");
212 MODULE_LICENSE("GPL v2");