kernel/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      BIT(31)
  28
  29 #define to_lpc32xx_pwm_chip(_chip) \
  30         container_of(_chip, struct lpc32xx_pwm_chip, chip)
  31
  32 static int lpc32xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  33                               int duty_ns, int period_ns)
  34 {
  35         struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
  36         unsigned long long c;
  37         int period_cycles, duty_cycles;
  38         u32 val;
  39         c = clk_get_rate(lpc32xx->clk);
  40
  41         /* The highest acceptable divisor is 256, which is represented by 0 */
  42         period_cycles = div64_u64(c * period_ns,
  43                                (unsigned long long)NSEC_PER_SEC * 256);
  44         if (!period_cycles)
  45                 period_cycles = 1;
  46         if (period_cycles > 255)
  47                 period_cycles = 0;
  48
  49         /* Compute 256 x #duty/period value and care for corner cases */
  50         duty_cycles = div64_u64((unsigned long long)(period_ns - duty_ns) * 256,
  51                                 period_ns);
  52         if (!duty_cycles)
  53                 duty_cycles = 1;
  54         if (duty_cycles > 255)
  55                 duty_cycles = 255;
  56
  57         val = readl(lpc32xx->base + (pwm->hwpwm << 2));
  58         val &= ~0xFFFF;
  59         val |= (period_cycles << 8) | duty_cycles;
  60         writel(val, lpc32xx->base + (pwm->hwpwm << 2));
  61
  62         return 0;
  63 }
  64
  65 static int lpc32xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  66 {
  67         struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
  68         u32 val;
  69         int ret;
  70
  71         ret = clk_enable(lpc32xx->clk);
  72         if (ret)
  73                 return ret;
  74
  75         val = readl(lpc32xx->base + (pwm->hwpwm << 2));
  76         val |= PWM_ENABLE;
  77         writel(val, lpc32xx->base + (pwm->hwpwm << 2));
  78
  79         return 0;
  80 }
  81
  82 static void lpc32xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
  83 {
  84         struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
  85         u32 val;
  86
  87         val = readl(lpc32xx->base + (pwm->hwpwm << 2));
  88         val &= ~PWM_ENABLE;
  89         writel(val, lpc32xx->base + (pwm->hwpwm << 2));
  90
  91         clk_disable(lpc32xx->clk);
  92 }
  93
  94 static const struct pwm_ops lpc32xx_pwm_ops = {
  95         .config = lpc32xx_pwm_config,
  96         .enable = lpc32xx_pwm_enable,
  97         .disable = lpc32xx_pwm_disable,
  98         .owner = THIS_MODULE,
  99 };
 100
 101 static int lpc32xx_pwm_probe(struct platform_device *pdev)
 102 {
 103         struct lpc32xx_pwm_chip *lpc32xx;
 104         struct resource *res;
 105         int ret;
 106
 107         lpc32xx = devm_kzalloc(&pdev->dev, sizeof(*lpc32xx), GFP_KERNEL);
 108         if (!lpc32xx)
 109                 return -ENOMEM;
 110
 111         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 112         lpc32xx->base = devm_ioremap_resource(&pdev->dev, res);
 113         if (IS_ERR(lpc32xx->base))
 114                 return PTR_ERR(lpc32xx->base);
 115
 116         lpc32xx->clk = devm_clk_get(&pdev->dev, NULL);
 117         if (IS_ERR(lpc32xx->clk))
 118                 return PTR_ERR(lpc32xx->clk);
 119
 120         lpc32xx->chip.dev = &pdev->dev;
 121         lpc32xx->chip.ops = &lpc32xx_pwm_ops;
 122         lpc32xx->chip.npwm = 1;
 123         lpc32xx->chip.base = -1;
 124
 125         ret = pwmchip_add(&lpc32xx->chip);
 126         if (ret < 0) {
 127                 dev_err(&pdev->dev, "failed to add PWM chip, error %d\n", ret);
 128                 return ret;
 129         }
 130
 131         platform_set_drvdata(pdev, lpc32xx);
 132
 133         return 0;
 134 }
 135
 136 static int lpc32xx_pwm_remove(struct platform_device *pdev)
 137 {
 138         struct lpc32xx_pwm_chip *lpc32xx = platform_get_drvdata(pdev);
 139         unsigned int i;
 140
 141         for (i = 0; i < lpc32xx->chip.npwm; i++)
 142                 pwm_disable(&lpc32xx->chip.pwms[i]);
 143
 144         return pwmchip_remove(&lpc32xx->chip);
 145 }
 146
 147 static const struct of_device_id lpc32xx_pwm_dt_ids[] = {
 148         { .compatible = "nxp,lpc3220-pwm", },
 149         { /* sentinel */ }
 150 };
 151 MODULE_DEVICE_TABLE(of, lpc32xx_pwm_dt_ids);
 152
 153 static struct platform_driver lpc32xx_pwm_driver = {
 154         .driver = {
 155                 .name = "lpc32xx-pwm",
 156                 .of_match_table = lpc32xx_pwm_dt_ids,
 157         },
 158         .probe = lpc32xx_pwm_probe,
 159         .remove = lpc32xx_pwm_remove,
 160 };
 161 module_platform_driver(lpc32xx_pwm_driver);
 162
 163 MODULE_ALIAS("platform:lpc32xx-pwm");
 164 MODULE_AUTHOR("Alexandre Pereira da Silva <aletes.xgr@gmail.com>");
 165 MODULE_DESCRIPTION("LPC32XX PWM Driver");
 166 MODULE_LICENSE("GPL v2");