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        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
  80static 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
  97static 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
 109static 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
 116static 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
 154static 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
 165static const struct of_device_id lpc32xx_pwm_dt_ids[] = {
 166        { .compatible = "nxp,lpc3220-pwm", },
 167        { /* sentinel */ }
 168};
 169MODULE_DEVICE_TABLE(of, lpc32xx_pwm_dt_ids);
 170
 171static 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};
 179module_platform_driver(lpc32xx_pwm_driver);
 180
 181MODULE_ALIAS("platform:lpc32xx-pwm");
 182MODULE_AUTHOR("Alexandre Pereira da Silva <aletes.xgr@gmail.com>");
 183MODULE_DESCRIPTION("LPC32XX PWM Driver");
 184MODULE_LICENSE("GPL v2");
 185
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