linux/drivers/pwm/pwm-lpc32xx.c
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   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
  21struct 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
  34static 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
  41        c = clk_get_rate(lpc32xx->clk) / 256;
  42        c = c * period_ns;
  43        do_div(c, NSEC_PER_SEC);
  44
  45        /* Handle high and low extremes */
  46        if (c == 0)
  47                c = 1;
  48        if (c > 255)
  49                c = 0; /* 0 set division by 256 */
  50        period_cycles = c;
  51
  52        c = 256 * duty_ns;
  53        do_div(c, period_ns);
  54        duty_cycles = c;
  55
  56        writel(PWM_ENABLE | PWM_RELOADV(period_cycles) | PWM_DUTY(duty_cycles),
  57                lpc32xx->base + (pwm->hwpwm << 2));
  58
  59        return 0;
  60}
  61
  62static int lpc32xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  63{
  64        struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
  65
  66        return clk_enable(lpc32xx->clk);
  67}
  68
  69static void lpc32xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
  70{
  71        struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
  72
  73        writel(0, lpc32xx->base + (pwm->hwpwm << 2));
  74        clk_disable(lpc32xx->clk);
  75}
  76
  77static const struct pwm_ops lpc32xx_pwm_ops = {
  78        .config = lpc32xx_pwm_config,
  79        .enable = lpc32xx_pwm_enable,
  80        .disable = lpc32xx_pwm_disable,
  81        .owner = THIS_MODULE,
  82};
  83
  84static int lpc32xx_pwm_probe(struct platform_device *pdev)
  85{
  86        struct lpc32xx_pwm_chip *lpc32xx;
  87        struct resource *res;
  88        int ret;
  89
  90        lpc32xx = devm_kzalloc(&pdev->dev, sizeof(*lpc32xx), GFP_KERNEL);
  91        if (!lpc32xx)
  92                return -ENOMEM;
  93
  94        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  95        if (!res)
  96                return -EINVAL;
  97
  98        lpc32xx->base = devm_request_and_ioremap(&pdev->dev, res);
  99        if (!lpc32xx->base)
 100                return -EADDRNOTAVAIL;
 101
 102        lpc32xx->clk = devm_clk_get(&pdev->dev, NULL);
 103        if (IS_ERR(lpc32xx->clk))
 104                return PTR_ERR(lpc32xx->clk);
 105
 106        lpc32xx->chip.dev = &pdev->dev;
 107        lpc32xx->chip.ops = &lpc32xx_pwm_ops;
 108        lpc32xx->chip.npwm = 2;
 109
 110        ret = pwmchip_add(&lpc32xx->chip);
 111        if (ret < 0) {
 112                dev_err(&pdev->dev, "failed to add PWM chip, error %d\n", ret);
 113                return ret;
 114        }
 115
 116        platform_set_drvdata(pdev, lpc32xx);
 117
 118        return 0;
 119}
 120
 121static int __devexit lpc32xx_pwm_remove(struct platform_device *pdev)
 122{
 123        struct lpc32xx_pwm_chip *lpc32xx = platform_get_drvdata(pdev);
 124
 125        clk_disable(lpc32xx->clk);
 126        return pwmchip_remove(&lpc32xx->chip);
 127}
 128
 129static struct of_device_id lpc32xx_pwm_dt_ids[] = {
 130        { .compatible = "nxp,lpc3220-pwm", },
 131        { /* sentinel */ }
 132};
 133MODULE_DEVICE_TABLE(of, lpc32xx_pwm_dt_ids);
 134
 135static struct platform_driver lpc32xx_pwm_driver = {
 136        .driver = {
 137                .name = "lpc32xx-pwm",
 138                .of_match_table = of_match_ptr(lpc32xx_pwm_dt_ids),
 139        },
 140        .probe = lpc32xx_pwm_probe,
 141        .remove = __devexit_p(lpc32xx_pwm_remove),
 142};
 143module_platform_driver(lpc32xx_pwm_driver);
 144
 145MODULE_ALIAS("platform:lpc32xx-pwm");
 146MODULE_AUTHOR("Alexandre Pereira da Silva <aletes.xgr@gmail.com>");
 147MODULE_DESCRIPTION("LPC32XX PWM Driver");
 148MODULE_LICENSE("GPL v2");
 149
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