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Linux/drivers/pwm/pwm-lpc32xx.c

  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 
 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 
 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 
 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 
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 
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 

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