/*
   * 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 bool nowayout = WATCHDOG_NOWAYOUT;
  module_param(nowayout, bool, 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
  ",
  			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
  ",
  			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
  ");
  		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
  ",
  			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
  ",
  			ret);

  	}

  	wdt_dev->timeout = timeout;

  	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 wm831x_wdt_probe(struct platform_device *pdev)

  {

  	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);

  	struct wm831x_pdata *chip_pdata = dev_get_platdata(pdev->dev.parent);

  	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
  ",
  			ret);

  		return ret;

  	}
  	reg = ret;
  
  	if (reg & WM831X_WDOG_DEBUG)
  		dev_warn(wm831x->dev, "Watchdog is paused
  ");

  	driver_data = devm_kzalloc(&pdev->dev, sizeof(*driver_data),
  				   GFP_KERNEL);

  	if (!driver_data)
  		return -ENOMEM;

  
  	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;

  	wm831x_wdt->parent = &pdev->dev;

  	watchdog_set_nowayout(wm831x_wdt, nowayout);

  	watchdog_set_drvdata(wm831x_wdt, driver_data);

  	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
  ", reg);
  	else
  		wm831x_wdt->timeout = wm831x_wdt_cfgs[i].time;

  	/* Apply any configuration */

  	if (chip_pdata)

  		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 = devm_gpio_request_one(&pdev->dev,
  						pdata->update_gpio,
  						GPIOF_OUT_INIT_LOW,
  						"Watchdog update");

  			if (ret < 0) {
  				dev_err(wm831x->dev,
  					"Failed to request update GPIO: %d
  ",
  					ret);

  				return ret;

  			}

  			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
  ", ret);

  			return ret;

  		}
  	}

  	ret = devm_watchdog_register_device(&pdev->dev, &driver_data->wdt);

  	if (ret != 0) {

  		dev_err(wm831x->dev, "watchdog_register_device() failed: %d
  ",
  			ret);

  		return ret;

  	}

  	return 0;
  }
  
  static struct platform_driver wm831x_wdt_driver = {
  	.probe = wm831x_wdt_probe,

  	.driver = {
  		.name = "wm831x-watchdog",
  	},
  };

  module_platform_driver(wm831x_wdt_driver);

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