pwm-jz4740.c

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/*
 *  Copyright (C) 2010, Lars-Peter Clausen <[email protected]>
 *  JZ4740 platform PWM support
 *
 *  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;  either version 2 of the License, or (at your
 *  option) any later version.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <linux/clk.h>
#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>

#include <asm/mach-jz4740/gpio.h>
#include <asm/mach-jz4740/timer.h>

#define NUM_PWM 8

static const unsigned int jz4740_pwm_gpio_list[NUM_PWM] = {
    JZ_GPIO_PWM0,
    JZ_GPIO_PWM1,
    JZ_GPIO_PWM2,
    JZ_GPIO_PWM3,
    JZ_GPIO_PWM4,
    JZ_GPIO_PWM5,
    JZ_GPIO_PWM6,
    JZ_GPIO_PWM7,
};

struct jz4740_pwm_chip {
    struct pwm_chip chip;
    struct clk *clk;
};

static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
{
    return container_of(chip, struct jz4740_pwm_chip, chip);
}

static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
{
    unsigned int gpio = jz4740_pwm_gpio_list[pwm->hwpwm];
    int ret;

    /*
     * Timers 0 and 1 are used for system tasks, so they are unavailable
     * for use as PWMs.
     */
    if (pwm->hwpwm < 2)
        return -EBUSY;

    ret = gpio_request(gpio, pwm->label);
    if (ret) {
        dev_err(chip->dev, "Failed to request GPIO#%u for PWM: %d\n",
            gpio, ret);
        return ret;
    }

    jz_gpio_set_function(gpio, JZ_GPIO_FUNC_PWM);

    jz4740_timer_start(pwm->hwpwm);

    return 0;
}

static void jz4740_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
    unsigned int gpio = jz4740_pwm_gpio_list[pwm->hwpwm];

    jz4740_timer_set_ctrl(pwm->hwpwm, 0);

    jz_gpio_set_function(gpio, JZ_GPIO_FUNC_NONE);
    gpio_free(gpio);

    jz4740_timer_stop(pwm->hwpwm);
}

static int jz4740_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
    uint32_t ctrl = jz4740_timer_get_ctrl(pwm->pwm);

    ctrl |= JZ_TIMER_CTRL_PWM_ENABLE;
    jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
    jz4740_timer_enable(pwm->hwpwm);

    return 0;
}

static void jz4740_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
    uint32_t ctrl = jz4740_timer_get_ctrl(pwm->hwpwm);

    ctrl &= ~JZ_TIMER_CTRL_PWM_ENABLE;
    jz4740_timer_disable(pwm->hwpwm);
    jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
}

static int jz4740_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
                 int duty_ns, int period_ns)
{
    struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip);
    unsigned long long tmp;
    unsigned long period, duty;
    unsigned int prescaler = 0;
    uint16_t ctrl;
    bool is_enabled;

    tmp = (unsigned long long)clk_get_rate(jz4740->clk) * period_ns;
    do_div(tmp, 1000000000);
    period = tmp;

    while (period > 0xffff && prescaler < 6) {
        period >>= 2;
        ++prescaler;
    }

    if (prescaler == 6)
        return -EINVAL;

    tmp = (unsigned long long)period * duty_ns;
    do_div(tmp, period_ns);
    duty = period - tmp;

    if (duty >= period)
        duty = period - 1;

    is_enabled = jz4740_timer_is_enabled(pwm->hwpwm);
    if (is_enabled)
        jz4740_pwm_disable(chip, pwm);

    jz4740_timer_set_count(pwm->hwpwm, 0);
    jz4740_timer_set_duty(pwm->hwpwm, duty);
    jz4740_timer_set_period(pwm->hwpwm, period);

    ctrl = JZ_TIMER_CTRL_PRESCALER(prescaler) | JZ_TIMER_CTRL_SRC_EXT |
        JZ_TIMER_CTRL_PWM_ABBRUPT_SHUTDOWN;

    jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);

    if (is_enabled)
        jz4740_pwm_enable(chip, pwm);

    return 0;
}

static const struct pwm_ops jz4740_pwm_ops = {
    .request = jz4740_pwm_request,
    .free = jz4740_pwm_free,
    .config = jz4740_pwm_config,
    .enable = jz4740_pwm_enable,
    .disable = jz4740_pwm_disable,
    .owner = THIS_MODULE,
};

static int __devinit jz4740_pwm_probe(struct platform_device *pdev)
{
    struct jz4740_pwm_chip *jz4740;
    int ret;

    jz4740 = devm_kzalloc(&pdev->dev, sizeof(*jz4740), GFP_KERNEL);
    if (!jz4740)
        return -ENOMEM;

    jz4740->clk = clk_get(NULL, "ext");
    if (IS_ERR(jz4740->clk))
        return PTR_ERR(jz4740->clk);

    jz4740->chip.dev = &pdev->dev;
    jz4740->chip.ops = &jz4740_pwm_ops;
    jz4740->chip.npwm = NUM_PWM;
    jz4740->chip.base = -1;

    ret = pwmchip_add(&jz4740->chip);
    if (ret < 0) {
        clk_put(jz4740->clk);
        return ret;
    }

    platform_set_drvdata(pdev, jz4740);

    return 0;
}

static int __devexit jz4740_pwm_remove(struct platform_device *pdev)
{
    struct jz4740_pwm_chip *jz4740 = platform_get_drvdata(pdev);
    int ret;

    ret = pwmchip_remove(&jz4740->chip);
    if (ret < 0)
        return ret;

    clk_put(jz4740->clk);

    return 0;
}

static struct platform_driver jz4740_pwm_driver = {
    .driver = {
        .name = "jz4740-pwm",
        .owner = THIS_MODULE,
    },
    .probe = jz4740_pwm_probe,
    .remove = __devexit_p(jz4740_pwm_remove),
};
module_platform_driver(jz4740_pwm_driver);

MODULE_AUTHOR("Lars-Peter Clausen <[email protected]>");
MODULE_DESCRIPTION("Ingenic JZ4740 PWM driver");
MODULE_ALIAS("platform:jz4740-pwm");
MODULE_LICENSE("GPL");