1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright 2014 Bart Tanghe <bart.tanghe@thomasmore.be>
4 */
5
6 #include <linux/clk.h>
7 #include <linux/err.h>
8 #include <linux/io.h>
9 #include <linux/module.h>
10 #include <linux/of.h>
11 #include <linux/platform_device.h>
12 #include <linux/pwm.h>
13
14 #define PWM_CONTROL 0x000
15 #define PWM_CONTROL_SHIFT(x) ((x) * 8)
16 #define PWM_CONTROL_MASK 0xff
17 #define PWM_MODE 0x80 /* set timer in PWM mode */
18 #define PWM_ENABLE (1 << 0)
19 #define PWM_POLARITY (1 << 4)
20
21 #define PERIOD(x) (((x) * 0x10) + 0x10)
22 #define DUTY(x) (((x) * 0x10) + 0x14)
23
24 #define PERIOD_MIN 0x2
25
26 struct bcm2835_pwm {
27 struct pwm_chip chip;
28 struct device *dev;
29 void __iomem *base;
30 struct clk *clk;
31 };
32
to_bcm2835_pwm(struct pwm_chip * chip)33 static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip)
34 {
35 return container_of(chip, struct bcm2835_pwm, chip);
36 }
37
bcm2835_pwm_request(struct pwm_chip * chip,struct pwm_device * pwm)38 static int bcm2835_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
39 {
40 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
41 u32 value;
42
43 value = readl(pc->base + PWM_CONTROL);
44 value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
45 value |= (PWM_MODE << PWM_CONTROL_SHIFT(pwm->hwpwm));
46 writel(value, pc->base + PWM_CONTROL);
47
48 return 0;
49 }
50
bcm2835_pwm_free(struct pwm_chip * chip,struct pwm_device * pwm)51 static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
52 {
53 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
54 u32 value;
55
56 value = readl(pc->base + PWM_CONTROL);
57 value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
58 writel(value, pc->base + PWM_CONTROL);
59 }
60
bcm2835_pwm_config(struct pwm_chip * chip,struct pwm_device * pwm,int duty_ns,int period_ns)61 static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
62 int duty_ns, int period_ns)
63 {
64 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
65 unsigned long rate = clk_get_rate(pc->clk);
66 unsigned long scaler;
67 u32 period;
68
69 if (!rate) {
70 dev_err(pc->dev, "failed to get clock rate\n");
71 return -EINVAL;
72 }
73
74 scaler = DIV_ROUND_CLOSEST(NSEC_PER_SEC, rate);
75 period = DIV_ROUND_CLOSEST(period_ns, scaler);
76
77 if (period < PERIOD_MIN)
78 return -EINVAL;
79
80 writel(DIV_ROUND_CLOSEST(duty_ns, scaler),
81 pc->base + DUTY(pwm->hwpwm));
82 writel(period, pc->base + PERIOD(pwm->hwpwm));
83
84 return 0;
85 }
86
bcm2835_pwm_enable(struct pwm_chip * chip,struct pwm_device * pwm)87 static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
88 {
89 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
90 u32 value;
91
92 value = readl(pc->base + PWM_CONTROL);
93 value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
94 writel(value, pc->base + PWM_CONTROL);
95
96 return 0;
97 }
98
bcm2835_pwm_disable(struct pwm_chip * chip,struct pwm_device * pwm)99 static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
100 {
101 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
102 u32 value;
103
104 value = readl(pc->base + PWM_CONTROL);
105 value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
106 writel(value, pc->base + PWM_CONTROL);
107 }
108
bcm2835_set_polarity(struct pwm_chip * chip,struct pwm_device * pwm,enum pwm_polarity polarity)109 static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
110 enum pwm_polarity polarity)
111 {
112 struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
113 u32 value;
114
115 value = readl(pc->base + PWM_CONTROL);
116
117 if (polarity == PWM_POLARITY_NORMAL)
118 value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
119 else
120 value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
121
122 writel(value, pc->base + PWM_CONTROL);
123
124 return 0;
125 }
126
127 static const struct pwm_ops bcm2835_pwm_ops = {
128 .request = bcm2835_pwm_request,
129 .free = bcm2835_pwm_free,
130 .config = bcm2835_pwm_config,
131 .enable = bcm2835_pwm_enable,
132 .disable = bcm2835_pwm_disable,
133 .set_polarity = bcm2835_set_polarity,
134 .owner = THIS_MODULE,
135 };
136
bcm2835_pwm_probe(struct platform_device * pdev)137 static int bcm2835_pwm_probe(struct platform_device *pdev)
138 {
139 struct bcm2835_pwm *pc;
140 struct resource *res;
141 int ret;
142
143 pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
144 if (!pc)
145 return -ENOMEM;
146
147 pc->dev = &pdev->dev;
148
149 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
150 pc->base = devm_ioremap_resource(&pdev->dev, res);
151 if (IS_ERR(pc->base))
152 return PTR_ERR(pc->base);
153
154 pc->clk = devm_clk_get(&pdev->dev, NULL);
155 if (IS_ERR(pc->clk))
156 return dev_err_probe(&pdev->dev, PTR_ERR(pc->clk),
157 "clock not found\n");
158
159 ret = clk_prepare_enable(pc->clk);
160 if (ret)
161 return ret;
162
163 pc->chip.dev = &pdev->dev;
164 pc->chip.ops = &bcm2835_pwm_ops;
165 pc->chip.base = -1;
166 pc->chip.npwm = 2;
167 pc->chip.of_xlate = of_pwm_xlate_with_flags;
168 pc->chip.of_pwm_n_cells = 3;
169
170 platform_set_drvdata(pdev, pc);
171
172 ret = pwmchip_add(&pc->chip);
173 if (ret < 0)
174 goto add_fail;
175
176 return 0;
177
178 add_fail:
179 clk_disable_unprepare(pc->clk);
180 return ret;
181 }
182
bcm2835_pwm_remove(struct platform_device * pdev)183 static int bcm2835_pwm_remove(struct platform_device *pdev)
184 {
185 struct bcm2835_pwm *pc = platform_get_drvdata(pdev);
186
187 clk_disable_unprepare(pc->clk);
188
189 return pwmchip_remove(&pc->chip);
190 }
191
192 static const struct of_device_id bcm2835_pwm_of_match[] = {
193 { .compatible = "brcm,bcm2835-pwm", },
194 { /* sentinel */ }
195 };
196 MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match);
197
198 static struct platform_driver bcm2835_pwm_driver = {
199 .driver = {
200 .name = "bcm2835-pwm",
201 .of_match_table = bcm2835_pwm_of_match,
202 },
203 .probe = bcm2835_pwm_probe,
204 .remove = bcm2835_pwm_remove,
205 };
206 module_platform_driver(bcm2835_pwm_driver);
207
208 MODULE_AUTHOR("Bart Tanghe <bart.tanghe@thomasmore.be>");
209 MODULE_DESCRIPTION("Broadcom BCM2835 PWM driver");
210 MODULE_LICENSE("GPL v2");
211
