pwm-lpc32xx.c

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/*
 * Copyright 2012 Alexandre Pereira da Silva <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2.
 *
 */

#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/slab.h>

struct lpc32xx_pwm_chip {
    struct pwm_chip chip;
    struct clk *clk;
    void __iomem *base;
};

#define PWM_ENABLE  (1 << 31)
#define PWM_RELOADV(x)  (((x) & 0xFF) << 8)
#define PWM_DUTY(x) ((x) & 0xFF)

#define to_lpc32xx_pwm_chip(_chip) \
    container_of(_chip, struct lpc32xx_pwm_chip, chip)

static int lpc32xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
                  int duty_ns, int period_ns)
{
    struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
    unsigned long long c;
    int period_cycles, duty_cycles;

    c = clk_get_rate(lpc32xx->clk) / 256;
    c = c * period_ns;
    do_div(c, NSEC_PER_SEC);

    /* Handle high and low extremes */
    if (c == 0)
        c = 1;
    if (c > 255)
        c = 0; /* 0 set division by 256 */
    period_cycles = c;

    c = 256 * duty_ns;
    do_div(c, period_ns);
    duty_cycles = c;

    writel(PWM_ENABLE | PWM_RELOADV(period_cycles) | PWM_DUTY(duty_cycles),
        lpc32xx->base + (pwm->hwpwm << 2));

    return 0;
}

static int lpc32xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
    struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);

    return clk_enable(lpc32xx->clk);
}

static void lpc32xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
    struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);

    writel(0, lpc32xx->base + (pwm->hwpwm << 2));
    clk_disable(lpc32xx->clk);
}

static const struct pwm_ops lpc32xx_pwm_ops = {
    .config = lpc32xx_pwm_config,
    .enable = lpc32xx_pwm_enable,
    .disable = lpc32xx_pwm_disable,
    .owner = THIS_MODULE,
};

static int lpc32xx_pwm_probe(struct platform_device *pdev)
{
    struct lpc32xx_pwm_chip *lpc32xx;
    struct resource *res;
    int ret;

    lpc32xx = devm_kzalloc(&pdev->dev, sizeof(*lpc32xx), GFP_KERNEL);
    if (!lpc32xx)
        return -ENOMEM;

    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (!res)
        return -EINVAL;

    lpc32xx->base = devm_request_and_ioremap(&pdev->dev, res);
    if (!lpc32xx->base)
        return -EADDRNOTAVAIL;

    lpc32xx->clk = devm_clk_get(&pdev->dev, NULL);
    if (IS_ERR(lpc32xx->clk))
        return PTR_ERR(lpc32xx->clk);

    lpc32xx->chip.dev = &pdev->dev;
    lpc32xx->chip.ops = &lpc32xx_pwm_ops;
    lpc32xx->chip.npwm = 2;

    ret = pwmchip_add(&lpc32xx->chip);
    if (ret < 0) {
        dev_err(&pdev->dev, "failed to add PWM chip, error %d\n", ret);
        return ret;
    }

    platform_set_drvdata(pdev, lpc32xx);

    return 0;
}

static int __devexit lpc32xx_pwm_remove(struct platform_device *pdev)
{
    struct lpc32xx_pwm_chip *lpc32xx = platform_get_drvdata(pdev);

    clk_disable(lpc32xx->clk);
    return pwmchip_remove(&lpc32xx->chip);
}

static struct of_device_id lpc32xx_pwm_dt_ids[] = {
    { .compatible = "nxp,lpc3220-pwm", },
    { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, lpc32xx_pwm_dt_ids);

static struct platform_driver lpc32xx_pwm_driver = {
    .driver = {
        .name = "lpc32xx-pwm",
        .of_match_table = of_match_ptr(lpc32xx_pwm_dt_ids),
    },
    .probe = lpc32xx_pwm_probe,
    .remove = __devexit_p(lpc32xx_pwm_remove),
};
module_platform_driver(lpc32xx_pwm_driver);

MODULE_ALIAS("platform:lpc32xx-pwm");
MODULE_AUTHOR("Alexandre Pereira da Silva <[email protected]>");
MODULE_DESCRIPTION("LPC32XX PWM Driver");
MODULE_LICENSE("GPL v2");