/*
   * Watchdog driver for Cirrus Logic EP93xx family of devices.
   *
   * Copyright (c) 2004 Ray Lehtiniemi
   * Copyright (c) 2006 Tower Technologies
   * Based on ep93xx driver, bits from alim7101_wdt.c
   *
   * Authors: Ray Lehtiniemi <rayl@mail.com>,
   *	Alessandro Zummo <a.zummo@towertech.it>
   *

   * Copyright (c) 2012 H Hartley Sweeten <hsweeten@visionengravers.com>
   *	Convert to a platform device and use the watchdog framework API
   *

   * This file is licensed under the terms of the GNU General Public
   * License version 2. This program is licensed "as is" without any
   * warranty of any kind, whether express or implied.
   *
   * This watchdog fires after 250msec, which is a too short interval
   * for us to rely on the user space daemon alone. So we ping the
   * wdt each ~200msec and eventually stop doing it if the user space
   * daemon dies.

   */

  #include <linux/platform_device.h>

  #include <linux/module.h>

  #include <linux/watchdog.h>

  #include <linux/io.h>

  /* default timeout (secs) */
  #define WDT_TIMEOUT 30

  static bool nowayout = WATCHDOG_NOWAYOUT;

  module_param(nowayout, bool, 0);
  MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");

  static unsigned int timeout;

  module_param(timeout, uint, 0);

  MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds.");

  #define EP93XX_WATCHDOG		0x00
  #define EP93XX_WDSTATUS		0x04

  struct ep93xx_wdt_priv {
  	void __iomem *mmio;
  	struct watchdog_device wdd;
  };

  static int ep93xx_wdt_start(struct watchdog_device *wdd)

  {

  	struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);

  	writel(0xaaaa, priv->mmio + EP93XX_WATCHDOG);

  
  	return 0;

  }

  static int ep93xx_wdt_stop(struct watchdog_device *wdd)

  {

  	struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
  
  	writel(0xaa55, priv->mmio + EP93XX_WATCHDOG);

  
  	return 0;

  }

  static int ep93xx_wdt_ping(struct watchdog_device *wdd)

  {

  	struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
  
  	writel(0x5555, priv->mmio + EP93XX_WATCHDOG);

  	return 0;

  }

  static const struct watchdog_info ep93xx_wdt_ident = {
  	.options	= WDIOF_CARDRESET |

  			  WDIOF_SETTIMEOUT |

  			  WDIOF_MAGICCLOSE |
  			  WDIOF_KEEPALIVEPING,
  	.identity	= "EP93xx Watchdog",

  };

  static const struct watchdog_ops ep93xx_wdt_ops = {

  	.owner		= THIS_MODULE,

  	.start		= ep93xx_wdt_start,
  	.stop		= ep93xx_wdt_stop,

  	.ping		= ep93xx_wdt_ping,

  };

  static int ep93xx_wdt_probe(struct platform_device *pdev)

  {

  	struct device *dev = &pdev->dev;

  	struct ep93xx_wdt_priv *priv;
  	struct watchdog_device *wdd;

  	unsigned long val;

  	int ret;

  	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);

  	if (!priv)
  		return -ENOMEM;

  	priv->mmio = devm_platform_ioremap_resource(pdev, 0);

  	if (IS_ERR(priv->mmio))
  		return PTR_ERR(priv->mmio);

  	val = readl(priv->mmio + EP93XX_WATCHDOG);

  	wdd = &priv->wdd;
  	wdd->bootstatus = (val & 0x01) ? WDIOF_CARDRESET : 0;
  	wdd->info = &ep93xx_wdt_ident;
  	wdd->ops = &ep93xx_wdt_ops;
  	wdd->min_timeout = 1;
  	wdd->max_hw_heartbeat_ms = 200;

  	wdd->parent = dev;

  	watchdog_set_nowayout(wdd, nowayout);

  	wdd->timeout = WDT_TIMEOUT;

  	watchdog_init_timeout(wdd, timeout, dev);

  	watchdog_set_drvdata(wdd, priv);

  	ret = devm_watchdog_register_device(dev, wdd);

  	if (ret)
  		return ret;

  	dev_info(dev, "EP93XX watchdog driver %s
  ",
  		 (val & 0x08) ? " (nCS1 disable detected)" : "");

  	return 0;

  }

  static struct platform_driver ep93xx_wdt_driver = {
  	.driver		= {

  		.name	= "ep93xx-wdt",
  	},
  	.probe		= ep93xx_wdt_probe,

  };
  
  module_platform_driver(ep93xx_wdt_driver);

  MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>");
  MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
  MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");

  MODULE_DESCRIPTION("EP93xx Watchdog");
  MODULE_LICENSE("GPL");