text: /*
   * Mediatek Watchdog Driver
   *
   * Copyright (C) 2014 Matthias Brugger
   *
   * Matthias Brugger <matthias.bgg@gmail.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.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * Based on sunxi_wdt.c
   */
  
  #include <linux/err.h>
  #include <linux/init.h>
  #include <linux/io.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/of.h>
  #include <linux/platform_device.h>
  #include <linux/types.h>
  #include <linux/watchdog.h>
  #include <linux/delay.h>
  
  #define WDT_MAX_TIMEOUT		31
  #define WDT_MIN_TIMEOUT		1
  #define WDT_LENGTH_TIMEOUT(n)	((n) << 5)
  
  #define WDT_LENGTH		0x04
  #define WDT_LENGTH_KEY		0x8
  
  #define WDT_RST			0x08
  #define WDT_RST_RELOAD		0x1971
  
  #define WDT_MODE		0x00
  #define WDT_MODE_EN		(1 << 0)
  #define WDT_MODE_EXT_POL_LOW	(0 << 1)
  #define WDT_MODE_EXT_POL_HIGH	(1 << 1)
  #define WDT_MODE_EXRST_EN	(1 << 2)
  #define WDT_MODE_IRQ_EN		(1 << 3)
  #define WDT_MODE_AUTO_START	(1 << 4)
  #define WDT_MODE_DUAL_EN	(1 << 6)
  #define WDT_MODE_KEY		0x22000000
  
  #define WDT_SWRST		0x14
  #define WDT_SWRST_KEY		0x1209
  
  #define DRV_NAME		"mtk-wdt"
  #define DRV_VERSION		"1.0"
  
  static bool nowayout = WATCHDOG_NOWAYOUT;
  static unsigned int timeout = WDT_MAX_TIMEOUT;
  
  struct mtk_wdt_dev {
  	struct watchdog_device wdt_dev;
  	void __iomem *wdt_base;
  };
  
  static int mtk_wdt_restart(struct watchdog_device *wdt_dev)
  {
  	struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
  	void __iomem *wdt_base;
  
  	wdt_base = mtk_wdt->wdt_base;
  
  	while (1) {
  		writel(WDT_SWRST_KEY, wdt_base + WDT_SWRST);
  		mdelay(5);
  	}
  
  	return 0;
  }
  
  static int mtk_wdt_ping(struct watchdog_device *wdt_dev)
  {
  	struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
  	void __iomem *wdt_base = mtk_wdt->wdt_base;
  
  	iowrite32(WDT_RST_RELOAD, wdt_base + WDT_RST);
  
  	return 0;
  }
  
  static int mtk_wdt_set_timeout(struct watchdog_device *wdt_dev,
  				unsigned int timeout)
  {
  	struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
  	void __iomem *wdt_base = mtk_wdt->wdt_base;
  	u32 reg;
  
  	wdt_dev->timeout = timeout;
  
  	/*
  	 * One bit is the value of 512 ticks
  	 * The clock has 32 KHz
  	 */
  	reg = WDT_LENGTH_TIMEOUT(timeout << 6) | WDT_LENGTH_KEY;
  	iowrite32(reg, wdt_base + WDT_LENGTH);
  
  	mtk_wdt_ping(wdt_dev);
  
  	return 0;
  }
  
  static int mtk_wdt_stop(struct watchdog_device *wdt_dev)
  {
  	struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
  	void __iomem *wdt_base = mtk_wdt->wdt_base;
  	u32 reg;
  
  	reg = readl(wdt_base + WDT_MODE);
  	reg &= ~WDT_MODE_EN;
  	reg |= WDT_MODE_KEY;
  	iowrite32(reg, wdt_base + WDT_MODE);
  
  	return 0;
  }
  
  static int mtk_wdt_start(struct watchdog_device *wdt_dev)
  {
  	u32 reg;
  	struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
  	void __iomem *wdt_base = mtk_wdt->wdt_base;
  	int ret;
  
  	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
  	if (ret < 0)
  		return ret;
  
  	reg = ioread32(wdt_base + WDT_MODE);
  	reg &= ~(WDT_MODE_IRQ_EN | WDT_MODE_DUAL_EN);
  	reg |= (WDT_MODE_EN | WDT_MODE_KEY);
  	iowrite32(reg, wdt_base + WDT_MODE);
  
  	return 0;
  }
  
  static const struct watchdog_info mtk_wdt_info = {
  	.identity	= DRV_NAME,
  	.options	= WDIOF_SETTIMEOUT |
  			  WDIOF_KEEPALIVEPING |
  			  WDIOF_MAGICCLOSE,
  };
  
  static const struct watchdog_ops mtk_wdt_ops = {
  	.owner		= THIS_MODULE,
  	.start		= mtk_wdt_start,
  	.stop		= mtk_wdt_stop,
  	.ping		= mtk_wdt_ping,
  	.set_timeout	= mtk_wdt_set_timeout,
  	.restart	= mtk_wdt_restart,
  };
  
  static int mtk_wdt_probe(struct platform_device *pdev)
  {
  	struct mtk_wdt_dev *mtk_wdt;
  	struct resource *res;
  	int err;
  
  	mtk_wdt = devm_kzalloc(&pdev->dev, sizeof(*mtk_wdt), GFP_KERNEL);
  	if (!mtk_wdt)
  		return -ENOMEM;
  
  	platform_set_drvdata(pdev, mtk_wdt);
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	mtk_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
  	if (IS_ERR(mtk_wdt->wdt_base))
  		return PTR_ERR(mtk_wdt->wdt_base);
  
  	mtk_wdt->wdt_dev.info = &mtk_wdt_info;
  	mtk_wdt->wdt_dev.ops = &mtk_wdt_ops;
  	mtk_wdt->wdt_dev.timeout = WDT_MAX_TIMEOUT;
  	mtk_wdt->wdt_dev.max_timeout = WDT_MAX_TIMEOUT;
  	mtk_wdt->wdt_dev.min_timeout = WDT_MIN_TIMEOUT;
  	mtk_wdt->wdt_dev.parent = &pdev->dev;
  
  	watchdog_init_timeout(&mtk_wdt->wdt_dev, timeout, &pdev->dev);
  	watchdog_set_nowayout(&mtk_wdt->wdt_dev, nowayout);
  	watchdog_set_restart_priority(&mtk_wdt->wdt_dev, 128);
  
  	watchdog_set_drvdata(&mtk_wdt->wdt_dev, mtk_wdt);
  
  	mtk_wdt_stop(&mtk_wdt->wdt_dev);
  
  	err = watchdog_register_device(&mtk_wdt->wdt_dev);
  	if (unlikely(err))
  		return err;
  
  	dev_info(&pdev->dev, "Watchdog enabled (timeout=%d sec, nowayout=%d)\n",
  			mtk_wdt->wdt_dev.timeout, nowayout);
  
  	return 0;
  }
  
  static void mtk_wdt_shutdown(struct platform_device *pdev)
  {
  	struct mtk_wdt_dev *mtk_wdt = platform_get_drvdata(pdev);
  
  	if (watchdog_active(&mtk_wdt->wdt_dev))
  		mtk_wdt_stop(&mtk_wdt->wdt_dev);
  }
  
  static int mtk_wdt_remove(struct platform_device *pdev)
  {
  	struct mtk_wdt_dev *mtk_wdt = platform_get_drvdata(pdev);
  
  	watchdog_unregister_device(&mtk_wdt->wdt_dev);
  
  	return 0;
  }
  
  #ifdef CONFIG_PM_SLEEP
  static int mtk_wdt_suspend(struct device *dev)
  {
  	struct mtk_wdt_dev *mtk_wdt = dev_get_drvdata(dev);
  
  	if (watchdog_active(&mtk_wdt->wdt_dev))
  		mtk_wdt_stop(&mtk_wdt->wdt_dev);
  
  	return 0;
  }
  
  static int mtk_wdt_resume(struct device *dev)
  {
  	struct mtk_wdt_dev *mtk_wdt = dev_get_drvdata(dev);
  
  	if (watchdog_active(&mtk_wdt->wdt_dev)) {
  		mtk_wdt_start(&mtk_wdt->wdt_dev);
  		mtk_wdt_ping(&mtk_wdt->wdt_dev);
  	}
  
  	return 0;
  }
  #endif
  
  static const struct of_device_id mtk_wdt_dt_ids[] = {
  	{ .compatible = "mediatek,mt6589-wdt" },
  	{ /* sentinel */ }
  };
  MODULE_DEVICE_TABLE(of, mtk_wdt_dt_ids);
  
  static const struct dev_pm_ops mtk_wdt_pm_ops = {
  	SET_SYSTEM_SLEEP_PM_OPS(mtk_wdt_suspend,
  				mtk_wdt_resume)
  };
  
  static struct platform_driver mtk_wdt_driver = {
  	.probe		= mtk_wdt_probe,
  	.remove		= mtk_wdt_remove,
  	.shutdown	= mtk_wdt_shutdown,
  	.driver		= {
  		.name		= DRV_NAME,
  		.pm		= &mtk_wdt_pm_ops,
  		.of_match_table	= mtk_wdt_dt_ids,
  	},
  };
  
  module_platform_driver(mtk_wdt_driver);
  
  module_param(timeout, uint, 0);
  MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
  
  module_param(nowayout, bool, 0);
  MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  			__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Matthias Brugger <matthias.bgg@gmail.com>");
  MODULE_DESCRIPTION("Mediatek WatchDog Timer Driver");
  MODULE_VERSION(DRV_VERSION);
  