/*
 * Watchdog driver for the wm831x PMICs
 *
 * Copyright (C) 2009 Wolfson Microelectronics
 *
 * 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
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <linux/uaccess.h>
#include <linux/gpio.h>

#include <linux/mfd/wm831x/core.h>
#include <linux/mfd/wm831x/pdata.h>
#include <linux/mfd/wm831x/watchdog.h>

static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout,
		 "Watchdog cannot be stopped once started (default="
		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

struct wm831x_wdt_drvdata {
	struct watchdog_device wdt;
	struct wm831x *wm831x;
	struct mutex lock;
	int update_gpio;
	int update_state;
};

/* We can't use the sub-second values here but they're included
 * for completeness.  */
static struct {
	unsigned int time;  /* Seconds */
	u16 val;            /* WDOG_TO value */
} wm831x_wdt_cfgs[] = {
	{  1, 2 },
	{  2, 3 },
	{  4, 4 },
	{  8, 5 },
	{ 16, 6 },
	{ 32, 7 },
	{ 33, 7 },  /* Actually 32.768s so include both, others round down */
};

static int wm831x_wdt_start(struct watchdog_device *wdt_dev)
{
	struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
	struct wm831x *wm831x = driver_data->wm831x;
	int ret;

	mutex_lock(&driver_data->lock);

	ret = wm831x_reg_unlock(wm831x);
	if (ret == 0) {
		ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
				      WM831X_WDOG_ENA, WM831X_WDOG_ENA);
		wm831x_reg_lock(wm831x);
	} else {
		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
			ret);
	}

	mutex_unlock(&driver_data->lock);

	return ret;
}

static int wm831x_wdt_stop(struct watchdog_device *wdt_dev)
{
	struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
	struct wm831x *wm831x = driver_data->wm831x;
	int ret;

	mutex_lock(&driver_data->lock);

	ret = wm831x_reg_unlock(wm831x);
	if (ret == 0) {
		ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
				      WM831X_WDOG_ENA, 0);
		wm831x_reg_lock(wm831x);
	} else {
		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
			ret);
	}

	mutex_unlock(&driver_data->lock);

	return ret;
}

static int wm831x_wdt_ping(struct watchdog_device *wdt_dev)
{
	struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
	struct wm831x *wm831x = driver_data->wm831x;
	int ret;
	u16 reg;

	mutex_lock(&driver_data->lock);

	if (driver_data->update_gpio) {
		gpio_set_value_cansleep(driver_data->update_gpio,
					driver_data->update_state);
		driver_data->update_state = !driver_data->update_state;
		ret = 0;
		goto out;
	}

	reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);

	if (!(reg & WM831X_WDOG_RST_SRC)) {
		dev_err(wm831x->dev, "Hardware watchdog update unsupported\n");
		ret = -EINVAL;
		goto out;
	}

	reg |= WM831X_WDOG_RESET;

	ret = wm831x_reg_unlock(wm831x);
	if (ret == 0) {
		ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
		wm831x_reg_lock(wm831x);
	} else {
		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
			ret);
	}

out:
	mutex_unlock(&driver_data->lock);

	return ret;
}

static int wm831x_wdt_set_timeout(struct watchdog_device *wdt_dev,
				  unsigned int timeout)
{
	struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
	struct wm831x *wm831x = driver_data->wm831x;
	int ret, i;

	for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
		if (wm831x_wdt_cfgs[i].time == timeout)
			break;
	if (i == ARRAY_SIZE(wm831x_wdt_cfgs))
		return -EINVAL;

	ret = wm831x_reg_unlock(wm831x);
	if (ret == 0) {
		ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
				      WM831X_WDOG_TO_MASK,
				      wm831x_wdt_cfgs[i].val);
		wm831x_reg_lock(wm831x);
	} else {
		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
			ret);
	}

	return ret;
}

static const struct watchdog_info wm831x_wdt_info = {
	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
	.identity = "WM831x Watchdog",
};

static const struct watchdog_ops wm831x_wdt_ops = {
	.owner = THIS_MODULE,
	.start = wm831x_wdt_start,
	.stop = wm831x_wdt_stop,
	.ping = wm831x_wdt_ping,
	.set_timeout = wm831x_wdt_set_timeout,
};

static int __devinit wm831x_wdt_probe(struct platform_device *pdev)
{
	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
	struct wm831x_pdata *chip_pdata;
	struct wm831x_watchdog_pdata *pdata;
	struct wm831x_wdt_drvdata *driver_data;
	struct watchdog_device *wm831x_wdt;
	int reg, ret, i;

	ret = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
	if (ret < 0) {
		dev_err(wm831x->dev, "Failed to read watchdog status: %d\n",
			ret);
		goto err;
	}
	reg = ret;

	if (reg & WM831X_WDOG_DEBUG)
		dev_warn(wm831x->dev, "Watchdog is paused\n");

	driver_data = kzalloc(sizeof(*driver_data), GFP_KERNEL);
	if (!driver_data) {
		dev_err(wm831x->dev, "Unable to alloacate watchdog device\n");
		ret = -ENOMEM;
		goto err;
	}

	mutex_init(&driver_data->lock);
	driver_data->wm831x = wm831x;

	wm831x_wdt = &driver_data->wdt;

	wm831x_wdt->info = &wm831x_wdt_info;
	wm831x_wdt->ops = &wm831x_wdt_ops;
	watchdog_set_drvdata(wm831x_wdt, driver_data);

	if (nowayout)
		wm831x_wdt->status |= WDOG_NO_WAY_OUT;

	reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
	reg &= WM831X_WDOG_TO_MASK;
	for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
		if (wm831x_wdt_cfgs[i].val == reg)
			break;
	if (i == ARRAY_SIZE(wm831x_wdt_cfgs))
		dev_warn(wm831x->dev,
			 "Unknown watchdog timeout: %x\n", reg);
	else
		wm831x_wdt->timeout = wm831x_wdt_cfgs[i].time;

	/* Apply any configuration */
	if (pdev->dev.parent->platform_data) {
		chip_pdata = pdev->dev.parent->platform_data;
		pdata = chip_pdata->watchdog;
	} else {
		pdata = NULL;
	}

	if (pdata) {
		reg &= ~(WM831X_WDOG_SECACT_MASK | WM831X_WDOG_PRIMACT_MASK |
			 WM831X_WDOG_RST_SRC);

		reg |= pdata->primary << WM831X_WDOG_PRIMACT_SHIFT;
		reg |= pdata->secondary << WM831X_WDOG_SECACT_SHIFT;
		reg |= pdata->software << WM831X_WDOG_RST_SRC_SHIFT;

		if (pdata->update_gpio) {
			ret = gpio_request(pdata->update_gpio,
					   "Watchdog update");
			if (ret < 0) {
				dev_err(wm831x->dev,
					"Failed to request update GPIO: %d\n",
					ret);
				goto err_alloc;
			}

			ret = gpio_direction_output(pdata->update_gpio, 0);
			if (ret != 0) {
				dev_err(wm831x->dev,
					"gpio_direction_output returned: %d\n",
					ret);
				goto err_gpio;
			}

			driver_data->update_gpio = pdata->update_gpio;

			/* Make sure the watchdog takes hardware updates */
			reg |= WM831X_WDOG_RST_SRC;
		}

		ret = wm831x_reg_unlock(wm831x);
		if (ret == 0) {
			ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
			wm831x_reg_lock(wm831x);
		} else {
			dev_err(wm831x->dev,
				"Failed to unlock security key: %d\n", ret);
			goto err_gpio;
		}
	}

	ret = watchdog_register_device(&driver_data->wdt);
	if (ret != 0) {
		dev_err(wm831x->dev, "watchdog_register_device() failed: %d\n",
			ret);
		goto err_gpio;
	}

	dev_set_drvdata(&pdev->dev, driver_data);

	return 0;

err_gpio:
	if (driver_data->update_gpio)
		gpio_free(driver_data->update_gpio);
err_alloc:
	kfree(driver_data);
err:
	return ret;
}

static int __devexit wm831x_wdt_remove(struct platform_device *pdev)
{
	struct wm831x_wdt_drvdata *driver_data = dev_get_drvdata(&pdev->dev);

	watchdog_unregister_device(&driver_data->wdt);

	if (driver_data->update_gpio)
		gpio_free(driver_data->update_gpio);

	return 0;
}

static struct platform_driver wm831x_wdt_driver = {
	.probe = wm831x_wdt_probe,
	.remove = __devexit_p(wm831x_wdt_remove),
	.driver = {
		.name = "wm831x-watchdog",
	},
};

static int __init wm831x_wdt_init(void)
{
	return platform_driver_register(&wm831x_wdt_driver);
}
module_init(wm831x_wdt_init);

static void __exit wm831x_wdt_exit(void)
{
	platform_driver_unregister(&wm831x_wdt_driver);
}
module_exit(wm831x_wdt_exit);

MODULE_AUTHOR("Mark Brown");
MODULE_DESCRIPTION("WM831x Watchdog");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:wm831x-watchdog");