/*
 *  Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
 *  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 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 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 = jz4740_pwm_remove,
};
module_platform_driver(jz4740_pwm_driver);

MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
MODULE_DESCRIPTION("Ingenic JZ4740 PWM driver");
MODULE_ALIAS("platform:jz4740-pwm");
MODULE_LICENSE("GPL");