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
to_bcm2835_pwm(struct pwm_chip * chip)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
bcm2835_pwm_request(struct pwm_chip * chip,struct pwm_device * pwm)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
bcm2835_pwm_free(struct pwm_chip * chip,struct pwm_device * pwm)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
bcm2835_pwm_config(struct pwm_chip * chip,struct pwm_device * pwm,int duty_ns,int period_ns)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
bcm2835_pwm_enable(struct pwm_chip * chip,struct pwm_device * pwm)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
bcm2835_pwm_disable(struct pwm_chip * chip,struct pwm_device * pwm)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
bcm2835_set_polarity(struct pwm_chip * chip,struct pwm_device * pwm,enum pwm_polarity polarity)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
bcm2835_pwm_probe(struct platform_device * pdev)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.base = -1;
164 pc->chip.npwm = 2;
165
166 platform_set_drvdata(pdev, pc);
167
168 ret = pwmchip_add(&pc->chip);
169 if (ret < 0)
170 goto add_fail;
171
172 return 0;
173
174 add_fail:
175 clk_disable_unprepare(pc->clk);
176 return ret;
177 }
178
bcm2835_pwm_remove(struct platform_device * pdev)179 static int bcm2835_pwm_remove(struct platform_device *pdev)
180 {
181 struct bcm2835_pwm *pc = platform_get_drvdata(pdev);
182
183 clk_disable_unprepare(pc->clk);
184
185 return pwmchip_remove(&pc->chip);
186 }
187
188 static const struct of_device_id bcm2835_pwm_of_match[] = {
189 { .compatible = "brcm,bcm2835-pwm", },
190 { /* sentinel */ }
191 };
192 MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match);
193
194 static struct platform_driver bcm2835_pwm_driver = {
195 .driver = {
196 .name = "bcm2835-pwm",
197 .of_match_table = bcm2835_pwm_of_match,
198 },
199 .probe = bcm2835_pwm_probe,
200 .remove = bcm2835_pwm_remove,
201 };
202 module_platform_driver(bcm2835_pwm_driver);
203
204 MODULE_AUTHOR("Bart Tanghe <bart.tanghe@thomasmore.be");
205 MODULE_DESCRIPTION("Broadcom BCM2835 PWM driver");
206 MODULE_LICENSE("GPL v2");
207