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         if (!res)
 128                 return -EINVAL;
 129
 130         lpc32xx->base = devm_ioremap_resource(&pdev->dev, res);
 131         if (IS_ERR(lpc32xx->base))
 132                 return PTR_ERR(lpc32xx->base);
 133
 134         lpc32xx->clk = devm_clk_get(&pdev->dev, NULL);
 135         if (IS_ERR(lpc32xx->clk))
 136                 return PTR_ERR(lpc32xx->clk);
 137
 138         lpc32xx->chip.dev = &pdev->dev;
 139         lpc32xx->chip.ops = &lpc32xx_pwm_ops;
 140         lpc32xx->chip.npwm = 2;
 141         lpc32xx->chip.base = -1;
 142
 143         ret = pwmchip_add(&lpc32xx->chip);
 144         if (ret < 0) {
 145                 dev_err(&pdev->dev, "failed to add PWM chip, error %d\n", ret);
 146                 return ret;
 147         }
 148
 149         platform_set_drvdata(pdev, lpc32xx);
 150
 151         return 0;
 152 }
 153
 154 static int lpc32xx_pwm_remove(struct platform_device *pdev)
 155 {
 156         struct lpc32xx_pwm_chip *lpc32xx = platform_get_drvdata(pdev);
 157         unsigned int i;
 158
 159         for (i = 0; i < lpc32xx->chip.npwm; i++)
 160                 pwm_disable(&lpc32xx->chip.pwms[i]);
 161
 162         return pwmchip_remove(&lpc32xx->chip);
 163 }
 164
 165 static const struct of_device_id lpc32xx_pwm_dt_ids[] = {
 166         { .compatible = "nxp,lpc3220-pwm", },
 167         { /* sentinel */ }
 168 };
 169 MODULE_DEVICE_TABLE(of, lpc32xx_pwm_dt_ids);
 170
 171 static struct platform_driver lpc32xx_pwm_driver = {
 172         .driver = {
 173                 .name = "lpc32xx-pwm",
 174                 .of_match_table = of_match_ptr(lpc32xx_pwm_dt_ids),
 175         },
 176         .probe = lpc32xx_pwm_probe,
 177         .remove = lpc32xx_pwm_remove,
 178 };
 179 module_platform_driver(lpc32xx_pwm_driver);
 180
 181 MODULE_ALIAS("platform:lpc32xx-pwm");
 182 MODULE_AUTHOR("Alexandre Pereira da Silva <aletes.xgr@gmail.com>");
 183 MODULE_DESCRIPTION("LPC32XX PWM Driver");
 184 MODULE_LICENSE("GPL v2");