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
to_bcm2835_pwm(struct pwm_chip * chip)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
bcm2835_pwm_request(struct pwm_chip * chip,struct pwm_device * pwm)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
bcm2835_pwm_free(struct pwm_chip * chip,struct pwm_device * pwm)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
bcm2835_pwm_config(struct pwm_chip * chip,struct pwm_device * pwm,int duty_ns,int period_ns)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
bcm2835_pwm_enable(struct pwm_chip * chip,struct pwm_device * pwm)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
bcm2835_pwm_disable(struct pwm_chip * chip,struct pwm_device * pwm)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
bcm2835_set_polarity(struct pwm_chip * chip,struct pwm_device * pwm,enum pwm_polarity polarity)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
bcm2835_pwm_probe(struct platform_device * pdev)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 pc->chip.of_xlate = of_pwm_xlate_with_flags;
172 pc->chip.of_pwm_n_cells = 3;
173
174 platform_set_drvdata(pdev, pc);
175
176 ret = pwmchip_add(&pc->chip);
177 if (ret < 0)
178 goto add_fail;
179
180 return 0;
181
182 add_fail:
183 clk_disable_unprepare(pc->clk);
184 return ret;
185 }
186
bcm2835_pwm_remove(struct platform_device * pdev)187 static int bcm2835_pwm_remove(struct platform_device *pdev)
188 {
189 struct bcm2835_pwm *pc = platform_get_drvdata(pdev);
190
191 clk_disable_unprepare(pc->clk);
192
193 return pwmchip_remove(&pc->chip);
194 }
195
196 static const struct of_device_id bcm2835_pwm_of_match[] = {
197 { .compatible = "brcm,bcm2835-pwm", },
198 { /* sentinel */ }
199 };
200 MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match);
201
202 static struct platform_driver bcm2835_pwm_driver = {
203 .driver = {
204 .name = "bcm2835-pwm",
205 .of_match_table = bcm2835_pwm_of_match,
206 },
207 .probe = bcm2835_pwm_probe,
208 .remove = bcm2835_pwm_remove,
209 };
210 module_platform_driver(bcm2835_pwm_driver);
211
212 MODULE_AUTHOR("Bart Tanghe <bart.tanghe@thomasmore.be>");
213 MODULE_DESCRIPTION("Broadcom BCM2835 PWM driver");
214 MODULE_LICENSE("GPL v2");
215