/*
 * drivers/pwm/pwm-pxa.c
 *
 * simple driver for PWM (Pulse Width Modulator) controller
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * 2008-02-13   initial version
 *              eric miao <eric.miao@marvell.com>
 */

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

#include <asm/div64.h>

#define HAS_SECONDARY_PWM       0x10

static const struct platform_device_id pwm_id_table[] = {
        /*   PWM    has_secondary_pwm? */
        { "pxa25x-pwm", 0 },
        { "pxa27x-pwm", HAS_SECONDARY_PWM },
        { "pxa168-pwm", 0 },
        { "pxa910-pwm", 0 },
        { },
};
MODULE_DEVICE_TABLE(platform, pwm_id_table);

/* PWM registers and bits definitions */
#define PWMCR           (0x00)
#define PWMDCR          (0x04)
#define PWMPCR          (0x08)

#define PWMCR_SD        (1 << 6)
#define PWMDCR_FD       (1 << 10)

struct pxa_pwm_chip {
        struct pwm_chip chip;
        struct device   *dev;

        struct clk      *clk;
        void __iomem    *mmio_base;
};

static inline struct pxa_pwm_chip *to_pxa_pwm_chip(struct pwm_chip *chip)
{
        return container_of(chip, struct pxa_pwm_chip, chip);
}

/*
 * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
 * duty_ns   = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
 */
static int pxa_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
                          int duty_ns, int period_ns)
{
        struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
        unsigned long long c;
        unsigned long period_cycles, prescale, pv, dc;
        unsigned long offset;
        int rc;

        offset = pwm->hwpwm ? 0x10 : 0;

        c = clk_get_rate(pc->clk);
        c = c * period_ns;
        do_div(c, 1000000000);
        period_cycles = c;

        if (period_cycles < 1)
                period_cycles = 1;
        prescale = (period_cycles - 1) / 1024;
        pv = period_cycles / (prescale + 1) - 1;

        if (prescale > 63)
                return -EINVAL;

        if (duty_ns == period_ns)
                dc = PWMDCR_FD;
        else
                dc = (pv + 1) * duty_ns / period_ns;

        /* NOTE: the clock to PWM has to be enabled first
         * before writing to the registers
         */
        rc = clk_prepare_enable(pc->clk);
        if (rc < 0)
                return rc;

        writel(prescale, pc->mmio_base + offset + PWMCR);
        writel(dc, pc->mmio_base + offset + PWMDCR);
        writel(pv, pc->mmio_base + offset + PWMPCR);

        clk_disable_unprepare(pc->clk);
        return 0;
}

static int pxa_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
        struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);

        return clk_prepare_enable(pc->clk);
}

static void pxa_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
        struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);

        clk_disable_unprepare(pc->clk);
}

static const struct pwm_ops pxa_pwm_ops = {
        .config = pxa_pwm_config,
        .enable = pxa_pwm_enable,
        .disable = pxa_pwm_disable,
        .owner = THIS_MODULE,
};

#ifdef CONFIG_OF
/*
 * Device tree users must create one device instance for each PWM channel.
 * Hence we dispense with the HAS_SECONDARY_PWM and "tell" the original driver
 * code that this is a single channel pxa25x-pwm.  Currently all devices are
 * supported identically.
 */
static const struct of_device_id pwm_of_match[] = {
        { .compatible = "marvell,pxa250-pwm", .data = &pwm_id_table[0]},
        { .compatible = "marvell,pxa270-pwm", .data = &pwm_id_table[0]},
        { .compatible = "marvell,pxa168-pwm", .data = &pwm_id_table[0]},
        { .compatible = "marvell,pxa910-pwm", .data = &pwm_id_table[0]},
        { }
};
MODULE_DEVICE_TABLE(of, pwm_of_match);
#else
#define pwm_of_match NULL
#endif

static const struct platform_device_id *pxa_pwm_get_id_dt(struct device *dev)
{
        const struct of_device_id *id = of_match_device(pwm_of_match, dev);

        return id ? id->data : NULL;
}

static struct pwm_device *
pxa_pwm_of_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
{
        struct pwm_device *pwm;

        pwm = pwm_request_from_chip(pc, 0, NULL);
        if (IS_ERR(pwm))
                return pwm;

        pwm->args.period = args->args[0];

        return pwm;
}

static int pwm_probe(struct platform_device *pdev)
{
        const struct platform_device_id *id = platform_get_device_id(pdev);
        struct pxa_pwm_chip *pwm;
        struct resource *r;
        int ret = 0;

        if (IS_ENABLED(CONFIG_OF) && id == NULL)
                id = pxa_pwm_get_id_dt(&pdev->dev);

        if (id == NULL)
                return -EINVAL;

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

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

        pwm->chip.dev = &pdev->dev;
        pwm->chip.ops = &pxa_pwm_ops;
        pwm->chip.base = -1;
        pwm->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1;

        if (IS_ENABLED(CONFIG_OF)) {
                pwm->chip.of_xlate = pxa_pwm_of_xlate;
                pwm->chip.of_pwm_n_cells = 1;
        }

        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
        if (IS_ERR(pwm->mmio_base))
                return PTR_ERR(pwm->mmio_base);

        ret = pwmchip_add(&pwm->chip);
        if (ret < 0) {
                dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
                return ret;
        }

        platform_set_drvdata(pdev, pwm);
        return 0;
}

static int pwm_remove(struct platform_device *pdev)
{
        struct pxa_pwm_chip *chip;

        chip = platform_get_drvdata(pdev);
        if (chip == NULL)
                return -ENODEV;

        return pwmchip_remove(&chip->chip);
}

static struct platform_driver pwm_driver = {
        .driver         = {
                .name   = "pxa25x-pwm",
                .of_match_table = pwm_of_match,
        },
        .probe          = pwm_probe,
        .remove         = pwm_remove,
        .id_table       = pwm_id_table,
};

module_platform_driver(pwm_driver);

MODULE_LICENSE("GPL v2");