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        /* The duty-cycle value is as follows:
  53         *
  54         *  DUTY-CYCLE     HIGH LEVEL
  55         *      1            99.9%
  56         *      25           90.0%
  57         *      128          50.0%
  58         *      220          10.0%
  59         *      255           0.1%
  60         *      0             0.0%
  61         *
  62         * In other words, the register value is duty-cycle % 256 with
  63         * duty-cycle in the range 1-256.
  64         */
  65        c = 256 * duty_ns;
  66        do_div(c, period_ns);
  67        if (c > 255)
  68                c = 255;
  69        duty_cycles = 256 - c;
  70
  71        writel(PWM_ENABLE | PWM_RELOADV(period_cycles) | PWM_DUTY(duty_cycles),
  72                lpc32xx->base + (pwm->hwpwm << 2));
  73
  74        return 0;
  75}
  76
  77static int lpc32xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  78{
  79        struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
  80
  81        return clk_enable(lpc32xx->clk);
  82}
  83
  84static void lpc32xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
  85{
  86        struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
  87
  88        writel(0, lpc32xx->base + (pwm->hwpwm << 2));
  89        clk_disable(lpc32xx->clk);
  90}
  91
  92static const struct pwm_ops lpc32xx_pwm_ops = {
  93        .config = lpc32xx_pwm_config,
  94        .enable = lpc32xx_pwm_enable,
  95        .disable = lpc32xx_pwm_disable,
  96        .owner = THIS_MODULE,
  97};
  98
  99static int lpc32xx_pwm_probe(struct platform_device *pdev)
 100{
 101        struct lpc32xx_pwm_chip *lpc32xx;
 102        struct resource *res;
 103        int ret;
 104
 105        lpc32xx = devm_kzalloc(&pdev->dev, sizeof(*lpc32xx), GFP_KERNEL);
 106        if (!lpc32xx)
 107                return -ENOMEM;
 108
 109        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 110        if (!res)
 111                return -EINVAL;
 112
 113        lpc32xx->base = devm_request_and_ioremap(&pdev->dev, res);
 114        if (!lpc32xx->base)
 115                return -EADDRNOTAVAIL;
 116
 117        lpc32xx->clk = devm_clk_get(&pdev->dev, NULL);
 118        if (IS_ERR(lpc32xx->clk))
 119                return PTR_ERR(lpc32xx->clk);
 120
 121        lpc32xx->chip.dev = &pdev->dev;
 122        lpc32xx->chip.ops = &lpc32xx_pwm_ops;
 123        lpc32xx->chip.npwm = 2;
 124        lpc32xx->chip.base = -1;
 125
 126        ret = pwmchip_add(&lpc32xx->chip);
 127        if (ret < 0) {
 128                dev_err(&pdev->dev, "failed to add PWM chip, error %d\n", ret);
 129                return ret;
 130        }
 131
 132        platform_set_drvdata(pdev, lpc32xx);
 133
 134        return 0;
 135}
 136
 137static int lpc32xx_pwm_remove(struct platform_device *pdev)
 138{
 139        struct lpc32xx_pwm_chip *lpc32xx = platform_get_drvdata(pdev);
 140        unsigned int i;
 141
 142        for (i = 0; i < lpc32xx->chip.npwm; i++)
 143                pwm_disable(&lpc32xx->chip.pwms[i]);
 144
 145        return pwmchip_remove(&lpc32xx->chip);
 146}
 147
 148static struct of_device_id lpc32xx_pwm_dt_ids[] = {
 149        { .compatible = "nxp,lpc3220-pwm", },
 150        { /* sentinel */ }
 151};
 152MODULE_DEVICE_TABLE(of, lpc32xx_pwm_dt_ids);
 153
 154static struct platform_driver lpc32xx_pwm_driver = {
 155        .driver = {
 156                .name = "lpc32xx-pwm",
 157                .of_match_table = of_match_ptr(lpc32xx_pwm_dt_ids),
 158        },
 159        .probe = lpc32xx_pwm_probe,
 160        .remove = lpc32xx_pwm_remove,
 161};
 162module_platform_driver(lpc32xx_pwm_driver);
 163
 164MODULE_ALIAS("platform:lpc32xx-pwm");
 165MODULE_AUTHOR("Alexandre Pereira da Silva <aletes.xgr@gmail.com>");
 166MODULE_DESCRIPTION("LPC32XX PWM Driver");
 167MODULE_LICENSE("GPL v2");
 168
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