/*
   * System monitoring driver for DA9055 PMICs.
   *
   * Copyright(c) 2012 Dialog Semiconductor Ltd.
   *
   * Author: David Dajun Chen <dchen@diasemi.com>
   *
   * 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.
   *
   */
  
  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/platform_device.h>
  #include <linux/watchdog.h>
  #include <linux/delay.h>
  
  #include <linux/mfd/da9055/core.h>
  #include <linux/mfd/da9055/reg.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) ")");
  
  #define DA9055_DEF_TIMEOUT	4
  #define DA9055_TWDMIN		256
  
  struct da9055_wdt_data {
  	struct watchdog_device wdt;
  	struct da9055 *da9055;
  	struct kref kref;
  };
  
  static const struct {
  	u8 reg_val;
  	int user_time;  /* In seconds */
  } da9055_wdt_maps[] = {
  	{ 0, 0 },
  	{ 1, 2 },
  	{ 2, 4 },
  	{ 3, 8 },
  	{ 4, 16 },
  	{ 5, 32 },
  	{ 5, 33 },  /* Actual time  32.768s so included both 32s and 33s */
  	{ 6, 65 },
  	{ 6, 66 },  /* Actual time 65.536s so include both, 65s and 66s */
  	{ 7, 131 },
  };
  
  static int da9055_wdt_set_timeout(struct watchdog_device *wdt_dev,
  				  unsigned int timeout)
  {
  	struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
  	struct da9055 *da9055 = driver_data->da9055;
  	int ret, i;
  
  	for (i = 0; i < ARRAY_SIZE(da9055_wdt_maps); i++)
  		if (da9055_wdt_maps[i].user_time == timeout)
  			break;
  
  	if (i == ARRAY_SIZE(da9055_wdt_maps))
  		ret = -EINVAL;
  	else
  		ret = da9055_reg_update(da9055, DA9055_REG_CONTROL_B,
  					DA9055_TWDSCALE_MASK,
  					da9055_wdt_maps[i].reg_val <<
  					DA9055_TWDSCALE_SHIFT);
  	if (ret < 0) {
  		dev_err(da9055->dev,
  			"Failed to update timescale bit, %d
  ", ret);
  		return ret;
  	}
  
  	wdt_dev->timeout = timeout;
  
  	return 0;
  }
  
  static int da9055_wdt_ping(struct watchdog_device *wdt_dev)
  {
  	struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
  	struct da9055 *da9055 = driver_data->da9055;
  
  	/*
  	 * We have a minimum time for watchdog window called TWDMIN. A write
  	 * to the watchdog before this elapsed time will cause an error.
  	 */
  	mdelay(DA9055_TWDMIN);
  
  	/* Reset the watchdog timer */
  	return da9055_reg_update(da9055, DA9055_REG_CONTROL_E,
  				 DA9055_WATCHDOG_MASK, 1);
  }
  
  static void da9055_wdt_release_resources(struct kref *r)
  {
  }
  
  static void da9055_wdt_ref(struct watchdog_device *wdt_dev)
  {
  	struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
  
  	kref_get(&driver_data->kref);
  }
  
  static void da9055_wdt_unref(struct watchdog_device *wdt_dev)
  {
  	struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
  
  	kref_put(&driver_data->kref, da9055_wdt_release_resources);
  }
  
  static int da9055_wdt_start(struct watchdog_device *wdt_dev)
  {
  	return da9055_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
  }
  
  static int da9055_wdt_stop(struct watchdog_device *wdt_dev)
  {
  	return da9055_wdt_set_timeout(wdt_dev, 0);
  }
  
  static struct watchdog_info da9055_wdt_info = {
  	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  	.identity	= "DA9055 Watchdog",
  };
  
  static const struct watchdog_ops da9055_wdt_ops = {
  	.owner = THIS_MODULE,
  	.start = da9055_wdt_start,
  	.stop = da9055_wdt_stop,
  	.ping = da9055_wdt_ping,
  	.set_timeout = da9055_wdt_set_timeout,
  	.ref = da9055_wdt_ref,
  	.unref = da9055_wdt_unref,
  };
  
  static int da9055_wdt_probe(struct platform_device *pdev)
  {
  	struct da9055 *da9055 = dev_get_drvdata(pdev->dev.parent);
  	struct da9055_wdt_data *driver_data;
  	struct watchdog_device *da9055_wdt;
  	int ret;
  
  	driver_data = devm_kzalloc(&pdev->dev, sizeof(*driver_data),
  				   GFP_KERNEL);
  	if (!driver_data) {
  		dev_err(da9055->dev, "Failed to allocate watchdog device
  ");
  		return -ENOMEM;
  	}
  
  	driver_data->da9055 = da9055;
  
  	da9055_wdt = &driver_data->wdt;
  
  	da9055_wdt->timeout = DA9055_DEF_TIMEOUT;
  	da9055_wdt->info = &da9055_wdt_info;
  	da9055_wdt->ops = &da9055_wdt_ops;
  	watchdog_set_nowayout(da9055_wdt, nowayout);
  	watchdog_set_drvdata(da9055_wdt, driver_data);
  
  	kref_init(&driver_data->kref);
  
  	ret = da9055_wdt_stop(da9055_wdt);
  	if (ret < 0) {
  		dev_err(&pdev->dev, "Failed to stop watchdog, %d
  ", ret);
  		goto err;
  	}
  
  	platform_set_drvdata(pdev, driver_data);
  
  	ret = watchdog_register_device(&driver_data->wdt);
  	if (ret != 0)
  		dev_err(da9055->dev, "watchdog_register_device() failed: %d
  ",
  			ret);
  
  err:
  	return ret;
  }
  
  static int da9055_wdt_remove(struct platform_device *pdev)
  {
  	struct da9055_wdt_data *driver_data = platform_get_drvdata(pdev);
  
  	watchdog_unregister_device(&driver_data->wdt);
  	kref_put(&driver_data->kref, da9055_wdt_release_resources);
  
  	return 0;
  }
  
  static struct platform_driver da9055_wdt_driver = {
  	.probe = da9055_wdt_probe,
  	.remove = da9055_wdt_remove,
  	.driver = {
  		.name	= "da9055-watchdog",
  	},
  };
  
  module_platform_driver(da9055_wdt_driver);
  
  MODULE_AUTHOR("David Dajun Chen <dchen@diasemi.com>");
  MODULE_DESCRIPTION("DA9055 watchdog");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("platform:da9055-watchdog");