1 /*
2 * Copyright 2012 Alexandre Pereira da Silva <aletes.xgr@gmail.com>
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
10 #include <linux/clk.h>
11 #include <linux/err.h>
12 #include <linux/io.h>
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/of.h>
16 #include <linux/of_address.h>
17 #include <linux/platform_device.h>
18 #include <linux/pwm.h>
19 #include <linux/slab.h>
20
21 struct lpc32xx_pwm_chip {
22 struct pwm_chip chip;
23 struct clk *clk;
24 void __iomem *base;
25 };
26
27 #define PWM_ENABLE (1 << 31)
28 #define PWM_RELOADV(x) (((x) & 0xFF) << 8)
29 #define PWM_DUTY(x) ((x) & 0xFF)
30
31 #define to_lpc32xx_pwm_chip(_chip) \
32 container_of(_chip, struct lpc32xx_pwm_chip, chip)
33
lpc32xx_pwm_config(struct pwm_chip * chip,struct pwm_device * pwm,int duty_ns,int period_ns)34 static int lpc32xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
35 int duty_ns, int period_ns)
36 {
37 struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
38 unsigned long long c;
39 int period_cycles, duty_cycles;
40 u32 val;
41
42 c = clk_get_rate(lpc32xx->clk) / 256;
43 c = c * period_ns;
44 do_div(c, NSEC_PER_SEC);
45
46 /* Handle high and low extremes */
47 if (c == 0)
48 c = 1;
49 if (c > 255)
50 c = 0; /* 0 set division by 256 */
51 period_cycles = c;
52
53 /* The duty-cycle value is as follows:
54 *
55 * DUTY-CYCLE HIGH LEVEL
56 * 1 99.9%
57 * 25 90.0%
58 * 128 50.0%
59 * 220 10.0%
60 * 255 0.1%
61 * 0 0.0%
62 *
63 * In other words, the register value is duty-cycle % 256 with
64 * duty-cycle in the range 1-256.
65 */
66 c = 256 * duty_ns;
67 do_div(c, period_ns);
68 if (c > 255)
69 c = 255;
70 duty_cycles = 256 - c;
71
72 val = readl(lpc32xx->base + (pwm->hwpwm << 2));
73 val &= ~0xFFFF;
74 val |= PWM_RELOADV(period_cycles) | PWM_DUTY(duty_cycles);
75 writel(val, lpc32xx->base + (pwm->hwpwm << 2));
76
77 return 0;
78 }
79
lpc32xx_pwm_enable(struct pwm_chip * chip,struct pwm_device * pwm)80 static int lpc32xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
81 {
82 struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
83 u32 val;
84 int ret;
85
86 ret = clk_enable(lpc32xx->clk);
87 if (ret)
88 return ret;
89
90 val = readl(lpc32xx->base + (pwm->hwpwm << 2));
91 val |= PWM_ENABLE;
92 writel(val, lpc32xx->base + (pwm->hwpwm << 2));
93
94 return 0;
95 }
96
lpc32xx_pwm_disable(struct pwm_chip * chip,struct pwm_device * pwm)97 static void lpc32xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
98 {
99 struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
100 u32 val;
101
102 val = readl(lpc32xx->base + (pwm->hwpwm << 2));
103 val &= ~PWM_ENABLE;
104 writel(val, lpc32xx->base + (pwm->hwpwm << 2));
105
106 clk_disable(lpc32xx->clk);
107 }
108
109 static const struct pwm_ops lpc32xx_pwm_ops = {
110 .config = lpc32xx_pwm_config,
111 .enable = lpc32xx_pwm_enable,
112 .disable = lpc32xx_pwm_disable,
113 .owner = THIS_MODULE,
114 };
115
lpc32xx_pwm_probe(struct platform_device * pdev)116 static int lpc32xx_pwm_probe(struct platform_device *pdev)
117 {
118 struct lpc32xx_pwm_chip *lpc32xx;
119 struct resource *res;
120 int ret;
121
122 lpc32xx = devm_kzalloc(&pdev->dev, sizeof(*lpc32xx), GFP_KERNEL);
123 if (!lpc32xx)
124 return -ENOMEM;
125
126 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
127 lpc32xx->base = devm_ioremap_resource(&pdev->dev, res);
128 if (IS_ERR(lpc32xx->base))
129 return PTR_ERR(lpc32xx->base);
130
131 lpc32xx->clk = devm_clk_get(&pdev->dev, NULL);
132 if (IS_ERR(lpc32xx->clk))
133 return PTR_ERR(lpc32xx->clk);
134
135 lpc32xx->chip.dev = &pdev->dev;
136 lpc32xx->chip.ops = &lpc32xx_pwm_ops;
137 lpc32xx->chip.npwm = 2;
138 lpc32xx->chip.base = -1;
139
140 ret = pwmchip_add(&lpc32xx->chip);
141 if (ret < 0) {
142 dev_err(&pdev->dev, "failed to add PWM chip, error %d\n", ret);
143 return ret;
144 }
145
146 platform_set_drvdata(pdev, lpc32xx);
147
148 return 0;
149 }
150
lpc32xx_pwm_remove(struct platform_device * pdev)151 static int lpc32xx_pwm_remove(struct platform_device *pdev)
152 {
153 struct lpc32xx_pwm_chip *lpc32xx = platform_get_drvdata(pdev);
154 unsigned int i;
155
156 for (i = 0; i < lpc32xx->chip.npwm; i++)
157 pwm_disable(&lpc32xx->chip.pwms[i]);
158
159 return pwmchip_remove(&lpc32xx->chip);
160 }
161
162 static const struct of_device_id lpc32xx_pwm_dt_ids[] = {
163 { .compatible = "nxp,lpc3220-pwm", },
164 { /* sentinel */ }
165 };
166 MODULE_DEVICE_TABLE(of, lpc32xx_pwm_dt_ids);
167
168 static struct platform_driver lpc32xx_pwm_driver = {
169 .driver = {
170 .name = "lpc32xx-pwm",
171 .owner = THIS_MODULE,
172 .of_match_table = lpc32xx_pwm_dt_ids,
173 },
174 .probe = lpc32xx_pwm_probe,
175 .remove = lpc32xx_pwm_remove,
176 };
177 module_platform_driver(lpc32xx_pwm_driver);
178
179 MODULE_ALIAS("platform:lpc32xx-pwm");
180 MODULE_AUTHOR("Alexandre Pereira da Silva <aletes.xgr@gmail.com>");
181 MODULE_DESCRIPTION("LPC32XX PWM Driver");
182 MODULE_LICENSE("GPL v2");
183