drivers/watchdog/dw_wdt.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright 2010-2011 Picochip Ltd., Jamie Iles
  * http://www.picochip.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 file implements a driver for the Synopsys DesignWare watchdog device
  * in the many subsystems. The watchdog has 16 different timeout periods
  * and these are a function of the input clock frequency.
  *
  * The DesignWare watchdog cannot be stopped once it has been started so we
  * use a software timer to implement a ping that will keep the watchdog alive.
  * If we receive an expected close for the watchdog then we keep the timer
  * running, otherwise the timer is stopped and the watchdog will expire.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/bitops.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/fs.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/miscdevice.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/notifier.h>
 #include <linux/of.h>
 #include <linux/pm.h>
 #include <linux/platform_device.h>
 #include <linux/reboot.h>
 #include <linux/spinlock.h>
 #include <linux/timer.h>
 #include <linux/uaccess.h>
 #include <linux/watchdog.h>

 #define WDOG_CONTROL_REG_OFFSET		    0x00
 #define WDOG_CONTROL_REG_WDT_EN_MASK	    0x01
 #define WDOG_TIMEOUT_RANGE_REG_OFFSET	    0x04
 #define WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT    4
 #define WDOG_CURRENT_COUNT_REG_OFFSET	    0x08
 #define WDOG_COUNTER_RESTART_REG_OFFSET     0x0c
 #define WDOG_COUNTER_RESTART_KICK_VALUE	    0x76

 /* The maximum TOP (timeout period) value that can be set in the watchdog. */
 #define DW_WDT_MAX_TOP		15

 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 WDT_TIMEOUT		(HZ / 2)

 static struct {
 	spinlock_t		lock;
 	void __iomem		*regs;
 	struct clk		*clk;
 	unsigned long		in_use;
 	unsigned long		next_heartbeat;
 	struct timer_list	timer;
 	int			expect_close;
 	struct notifier_block	restart_handler;
 } dw_wdt;

 static inline int dw_wdt_is_enabled(void)
 {
 	return readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET) &
 		WDOG_CONTROL_REG_WDT_EN_MASK;
 }

 static inline int dw_wdt_top_in_seconds(unsigned top)
 {
 	/*
 	 * There are 16 possible timeout values in 0..15 where the number of
 	 * cycles is 2 ^ (16 + i) and the watchdog counts down.
 	 */
 	return (1 << (16 + top)) / clk_get_rate(dw_wdt.clk);
 }

 static int dw_wdt_get_top(void)
 {
 	int top = readl(dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;

 	return dw_wdt_top_in_seconds(top);
 }

 static inline void dw_wdt_set_next_heartbeat(void)
 {
 	dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ;
 }

 static int dw_wdt_set_top(unsigned top_s)
 {
 	int i, top_val = DW_WDT_MAX_TOP;

 	/*
 	 * Iterate over the timeout values until we find the closest match. We
 	 * always look for >=.
 	 */
 	for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
 		if (dw_wdt_top_in_seconds(i) >= top_s) {
 			top_val = i;
 			break;
 		}

 	/* Set the new value in the watchdog. */
 	writel(top_val | top_val << WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT,
 		dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);

 	dw_wdt_set_next_heartbeat();

 	return dw_wdt_top_in_seconds(top_val);
 }

 static void dw_wdt_keepalive(void)
 {
 	writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
 	       WDOG_COUNTER_RESTART_REG_OFFSET);
 }

 static int dw_wdt_restart_handle(struct notifier_block *this,
 				unsigned long mode, void *cmd)
 {
 	u32 val;

 	writel(0, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
 	val = readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
 	if (val & WDOG_CONTROL_REG_WDT_EN_MASK)
 		writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
 			WDOG_COUNTER_RESTART_REG_OFFSET);
 	else
 		writel(WDOG_CONTROL_REG_WDT_EN_MASK,
 		       dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);

 	/* wait for reset to assert... */
 	mdelay(500);

 	return NOTIFY_DONE;
 }

 static void dw_wdt_ping(unsigned long data)
 {
 	if (time_before(jiffies, dw_wdt.next_heartbeat) ||
 	    (!nowayout && !dw_wdt.in_use)) {
 		dw_wdt_keepalive();
 		mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
 	} else
 		pr_crit("keepalive missed, machine will reset\n");
 }

 static int dw_wdt_open(struct inode *inode, struct file *filp)
 {
 	if (test_and_set_bit(0, &dw_wdt.in_use))
 		return -EBUSY;

 	/* Make sure we don't get unloaded. */
 	__module_get(THIS_MODULE);

 	spin_lock(&dw_wdt.lock);
 	if (!dw_wdt_is_enabled()) {
 		/*
 		 * The watchdog is not currently enabled. Set the timeout to
 		 * the maximum and then start it.
 		 */
 		dw_wdt_set_top(DW_WDT_MAX_TOP);
 		writel(WDOG_CONTROL_REG_WDT_EN_MASK,
 		       dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
 	}

 	dw_wdt_set_next_heartbeat();

 	spin_unlock(&dw_wdt.lock);

 	return nonseekable_open(inode, filp);
 }

 static ssize_t dw_wdt_write(struct file *filp, const char __user *buf,
 			    size_t len, loff_t *offset)
 {
 	if (!len)
 		return 0;

 	if (!nowayout) {
 		size_t i;

 		dw_wdt.expect_close = 0;

 		for (i = 0; i < len; ++i) {
 			char c;

 			if (get_user(c, buf + i))
 				return -EFAULT;

 			if (c == 'V') {
 				dw_wdt.expect_close = 1;
 				break;
 			}
 		}
 	}

 	dw_wdt_set_next_heartbeat();
 	mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);

 	return len;
 }

 static u32 dw_wdt_time_left(void)
 {
 	return readl(dw_wdt.regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
 		clk_get_rate(dw_wdt.clk);
 }

 static const struct watchdog_info dw_wdt_ident = {
 	.options	= WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 			  WDIOF_MAGICCLOSE,
 	.identity	= "Synopsys DesignWare Watchdog",
 };

 static long dw_wdt_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	unsigned long val;
 	int timeout;

 	switch (cmd) {
 	case WDIOC_GETSUPPORT:
 		return copy_to_user((void __user *)arg, &dw_wdt_ident,
 				    sizeof(dw_wdt_ident)) ? -EFAULT : 0;

 	case WDIOC_GETSTATUS:
 	case WDIOC_GETBOOTSTATUS:
 		return put_user(0, (int __user *)arg);

 	case WDIOC_KEEPALIVE:
 		dw_wdt_set_next_heartbeat();
 		return 0;

 	case WDIOC_SETTIMEOUT:
 		if (get_user(val, (int __user *)arg))
 			return -EFAULT;
 		timeout = dw_wdt_set_top(val);
 		return put_user(timeout , (int __user *)arg);

 	case WDIOC_GETTIMEOUT:
 		return put_user(dw_wdt_get_top(), (int __user *)arg);

 	case WDIOC_GETTIMELEFT:
 		/* Get the time left until expiry. */
 		if (get_user(val, (int __user *)arg))
 			return -EFAULT;
 		return put_user(dw_wdt_time_left(), (int __user *)arg);

 	default:
 		return -ENOTTY;
 	}
 }

 static int dw_wdt_release(struct inode *inode, struct file *filp)
 {
 	clear_bit(0, &dw_wdt.in_use);

 	if (!dw_wdt.expect_close) {
 		del_timer(&dw_wdt.timer);

 		if (!nowayout)
 			pr_crit("unexpected close, system will reboot soon\n");
 		else
 			pr_crit("watchdog cannot be disabled, system will reboot soon\n");
 	}

 	dw_wdt.expect_close = 0;

 	return 0;
 }

 #ifdef CONFIG_PM_SLEEP
 static int dw_wdt_suspend(struct device *dev)
 {
 	clk_disable_unprepare(dw_wdt.clk);

 	return 0;
 }

 static int dw_wdt_resume(struct device *dev)
 {
 	int err = clk_prepare_enable(dw_wdt.clk);

 	if (err)
 		return err;

 	dw_wdt_keepalive();

 	return 0;
 }
 #endif /* CONFIG_PM_SLEEP */

 static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);

 static const struct file_operations wdt_fops = {
 	.owner		= THIS_MODULE,
 	.llseek		= no_llseek,
 	.open		= dw_wdt_open,
 	.write		= dw_wdt_write,
 	.unlocked_ioctl	= dw_wdt_ioctl,
 	.release	= dw_wdt_release
 };

 static struct miscdevice dw_wdt_miscdev = {
 	.fops		= &wdt_fops,
 	.name		= "watchdog",
 	.minor		= WATCHDOG_MINOR,
 };

 static int dw_wdt_drv_probe(struct platform_device *pdev)
 {
 	int ret;
 	struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);

 	dw_wdt.regs = devm_ioremap_resource(&pdev->dev, mem);
 	if (IS_ERR(dw_wdt.regs))
 		return PTR_ERR(dw_wdt.regs);

 	dw_wdt.clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(dw_wdt.clk))
 		return PTR_ERR(dw_wdt.clk);

 	ret = clk_prepare_enable(dw_wdt.clk);
 	if (ret)
 		return ret;

 	spin_lock_init(&dw_wdt.lock);

 	ret = misc_register(&dw_wdt_miscdev);
 	if (ret)
 		goto out_disable_clk;

 	dw_wdt.restart_handler.notifier_call = dw_wdt_restart_handle;
 	dw_wdt.restart_handler.priority = 128;
 	ret = register_restart_handler(&dw_wdt.restart_handler);
 	if (ret)
 		pr_warn("cannot register restart handler\n");

 	dw_wdt_set_next_heartbeat();
 	setup_timer(&dw_wdt.timer, dw_wdt_ping, 0);
 	mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);

 	return 0;

 out_disable_clk:
 	clk_disable_unprepare(dw_wdt.clk);

 	return ret;
 }

 static int dw_wdt_drv_remove(struct platform_device *pdev)
 {
 	unregister_restart_handler(&dw_wdt.restart_handler);

 	misc_deregister(&dw_wdt_miscdev);

 	clk_disable_unprepare(dw_wdt.clk);

 	return 0;
 }

 #ifdef CONFIG_OF
 static const struct of_device_id dw_wdt_of_match[] = {
 	{ .compatible = "snps,dw-wdt", },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, dw_wdt_of_match);
 #endif

 static struct platform_driver dw_wdt_driver = {
 	.probe		= dw_wdt_drv_probe,
 	.remove		= dw_wdt_drv_remove,
 	.driver		= {
 		.name	= "dw_wdt",
 		.of_match_table = of_match_ptr(dw_wdt_of_match),
 		.pm	= &dw_wdt_pm_ops,
 	},
 };

 module_platform_driver(dw_wdt_driver);

 MODULE_AUTHOR("Jamie Iles");
 MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
 MODULE_LICENSE("GPL");
	/*
	* Copyright 2010-2011 Picochip Ltd., Jamie Iles
	* http://www.picochip.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 file implements a driver for the Synopsys DesignWare watchdog device
	* in the many subsystems. The watchdog has 16 different timeout periods
	* and these are a function of the input clock frequency.
	*
	* The DesignWare watchdog cannot be stopped once it has been started so we
	* use a software timer to implement a ping that will keep the watchdog alive.
	* If we receive an expected close for the watchdog then we keep the timer
	* running, otherwise the timer is stopped and the watchdog will expire.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/bitops.h>
	#include <linux/clk.h>
	#include <linux/delay.h>
	#include <linux/device.h>
	#include <linux/err.h>
	#include <linux/fs.h>
	#include <linux/io.h>
	#include <linux/kernel.h>
	#include <linux/miscdevice.h>
	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/notifier.h>
	#include <linux/of.h>
	#include <linux/pm.h>
	#include <linux/platform_device.h>
	#include <linux/reboot.h>
	#include <linux/spinlock.h>
	#include <linux/timer.h>
	#include <linux/uaccess.h>
	#include <linux/watchdog.h>

	#define WDOG_CONTROL_REG_OFFSET 0x00
	#define WDOG_CONTROL_REG_WDT_EN_MASK 0x01
	#define WDOG_TIMEOUT_RANGE_REG_OFFSET 0x04
	#define WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT 4
	#define WDOG_CURRENT_COUNT_REG_OFFSET 0x08
	#define WDOG_COUNTER_RESTART_REG_OFFSET 0x0c
	#define WDOG_COUNTER_RESTART_KICK_VALUE 0x76

	/* The maximum TOP (timeout period) value that can be set in the watchdog. */
	#define DW_WDT_MAX_TOP 15

	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 WDT_TIMEOUT (HZ / 2)

	static struct {
	spinlock_t lock;
	void __iomem *regs;
	struct clk *clk;
	unsigned long in_use;
	unsigned long next_heartbeat;
	struct timer_list timer;
	int expect_close;
	struct notifier_block restart_handler;
	} dw_wdt;

	static inline int dw_wdt_is_enabled(void)
	{
	return readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET) &
	WDOG_CONTROL_REG_WDT_EN_MASK;
	}

	static inline int dw_wdt_top_in_seconds(unsigned top)
	{
	/*
	* There are 16 possible timeout values in 0..15 where the number of
	* cycles is 2 ^ (16 + i) and the watchdog counts down.
	*/
	return (1 << (16 + top)) / clk_get_rate(dw_wdt.clk);
	}

	static int dw_wdt_get_top(void)
	{
	int top = readl(dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;

	return dw_wdt_top_in_seconds(top);
	}

	static inline void dw_wdt_set_next_heartbeat(void)
	{
	dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ;
	}

	static int dw_wdt_set_top(unsigned top_s)
	{
	int i, top_val = DW_WDT_MAX_TOP;

	/*
	* Iterate over the timeout values until we find the closest match. We
	* always look for >=.
	*/
	for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
	if (dw_wdt_top_in_seconds(i) >= top_s) {
	top_val = i;
	break;
	}

	/* Set the new value in the watchdog. */
	writel(top_val \| top_val << WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT,
	dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);

	dw_wdt_set_next_heartbeat();

	return dw_wdt_top_in_seconds(top_val);
	}

	static void dw_wdt_keepalive(void)
	{
	writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
	WDOG_COUNTER_RESTART_REG_OFFSET);
	}

	static int dw_wdt_restart_handle(struct notifier_block *this,
	unsigned long mode, void *cmd)
	{
	u32 val;

	writel(0, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
	val = readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
	if (val & WDOG_CONTROL_REG_WDT_EN_MASK)
	writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
	WDOG_COUNTER_RESTART_REG_OFFSET);
	else
	writel(WDOG_CONTROL_REG_WDT_EN_MASK,
	dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);

	/* wait for reset to assert... */
	mdelay(500);

	return NOTIFY_DONE;
	}

	static void dw_wdt_ping(unsigned long data)
	{
	if (time_before(jiffies, dw_wdt.next_heartbeat) \|\|
	(!nowayout && !dw_wdt.in_use)) {
	dw_wdt_keepalive();
	mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
	} else
	pr_crit("keepalive missed, machine will reset\n");
	}

	static int dw_wdt_open(struct inode inode, struct file filp)
	{
	if (test_and_set_bit(0, &dw_wdt.in_use))
	return -EBUSY;

	/* Make sure we don't get unloaded. */
	__module_get(THIS_MODULE);

	spin_lock(&dw_wdt.lock);
	if (!dw_wdt_is_enabled()) {
	/*
	* The watchdog is not currently enabled. Set the timeout to
	* the maximum and then start it.
	*/
	dw_wdt_set_top(DW_WDT_MAX_TOP);
	writel(WDOG_CONTROL_REG_WDT_EN_MASK,
	dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
	}

	dw_wdt_set_next_heartbeat();

	spin_unlock(&dw_wdt.lock);

	return nonseekable_open(inode, filp);
	}

	static ssize_t dw_wdt_write(struct file filp, const char __user buf,
	size_t len, loff_t *offset)
	{
	if (!len)
	return 0;

	if (!nowayout) {
	size_t i;

	dw_wdt.expect_close = 0;

	for (i = 0; i < len; ++i) {
	char c;

	if (get_user(c, buf + i))
	return -EFAULT;

	if (c == 'V') {
	dw_wdt.expect_close = 1;
	break;
	}
	}
	}

	dw_wdt_set_next_heartbeat();
	mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);

	return len;
	}

	static u32 dw_wdt_time_left(void)
	{
	return readl(dw_wdt.regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
	clk_get_rate(dw_wdt.clk);
	}

	static const struct watchdog_info dw_wdt_ident = {
	.options = WDIOF_KEEPALIVEPING \| WDIOF_SETTIMEOUT \|
	WDIOF_MAGICCLOSE,
	.identity = "Synopsys DesignWare Watchdog",
	};

	static long dw_wdt_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
	{
	unsigned long val;
	int timeout;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
	return copy_to_user((void __user *)arg, &dw_wdt_ident,
	sizeof(dw_wdt_ident)) ? -EFAULT : 0;

	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
	return put_user(0, (int __user *)arg);

	case WDIOC_KEEPALIVE:
	dw_wdt_set_next_heartbeat();
	return 0;

	case WDIOC_SETTIMEOUT:
	if (get_user(val, (int __user *)arg))
	return -EFAULT;
	timeout = dw_wdt_set_top(val);
	return put_user(timeout , (int __user *)arg);

	case WDIOC_GETTIMEOUT:
	return put_user(dw_wdt_get_top(), (int __user *)arg);

	case WDIOC_GETTIMELEFT:
	/* Get the time left until expiry. */
	if (get_user(val, (int __user *)arg))
	return -EFAULT;
	return put_user(dw_wdt_time_left(), (int __user *)arg);

	default:
	return -ENOTTY;
	}
	}

	static int dw_wdt_release(struct inode inode, struct file filp)
	{
	clear_bit(0, &dw_wdt.in_use);

	if (!dw_wdt.expect_close) {
	del_timer(&dw_wdt.timer);

	if (!nowayout)
	pr_crit("unexpected close, system will reboot soon\n");
	else
	pr_crit("watchdog cannot be disabled, system will reboot soon\n");
	}

	dw_wdt.expect_close = 0;

	return 0;
	}

	#ifdef CONFIG_PM_SLEEP
	static int dw_wdt_suspend(struct device *dev)
	{
	clk_disable_unprepare(dw_wdt.clk);

	return 0;
	}

	static int dw_wdt_resume(struct device *dev)
	{
	int err = clk_prepare_enable(dw_wdt.clk);

	if (err)
	return err;

	dw_wdt_keepalive();

	return 0;
	}
	#endif /* CONFIG_PM_SLEEP */

	static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);

	static const struct file_operations wdt_fops = {
	.owner = THIS_MODULE,
	.llseek = no_llseek,
	.open = dw_wdt_open,
	.write = dw_wdt_write,
	.unlocked_ioctl = dw_wdt_ioctl,
	.release = dw_wdt_release
	};

	static struct miscdevice dw_wdt_miscdev = {
	.fops = &wdt_fops,
	.name = "watchdog",
	.minor = WATCHDOG_MINOR,
	};

	static int dw_wdt_drv_probe(struct platform_device *pdev)
	{
	int ret;
	struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	dw_wdt.regs = devm_ioremap_resource(&pdev->dev, mem);
	if (IS_ERR(dw_wdt.regs))
	return PTR_ERR(dw_wdt.regs);

	dw_wdt.clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(dw_wdt.clk))
	return PTR_ERR(dw_wdt.clk);

	ret = clk_prepare_enable(dw_wdt.clk);
	if (ret)
	return ret;

	spin_lock_init(&dw_wdt.lock);

	ret = misc_register(&dw_wdt_miscdev);
	if (ret)
	goto out_disable_clk;

	dw_wdt.restart_handler.notifier_call = dw_wdt_restart_handle;
	dw_wdt.restart_handler.priority = 128;
	ret = register_restart_handler(&dw_wdt.restart_handler);
	if (ret)
	pr_warn("cannot register restart handler\n");

	dw_wdt_set_next_heartbeat();
	setup_timer(&dw_wdt.timer, dw_wdt_ping, 0);
	mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);

	return 0;

	out_disable_clk:
	clk_disable_unprepare(dw_wdt.clk);

	return ret;
	}

	static int dw_wdt_drv_remove(struct platform_device *pdev)
	{
	unregister_restart_handler(&dw_wdt.restart_handler);

	misc_deregister(&dw_wdt_miscdev);

	clk_disable_unprepare(dw_wdt.clk);

	return 0;
	}

	#ifdef CONFIG_OF
	static const struct of_device_id dw_wdt_of_match[] = {
	{ .compatible = "snps,dw-wdt", },
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, dw_wdt_of_match);
	#endif

	static struct platform_driver dw_wdt_driver = {
	.probe = dw_wdt_drv_probe,
	.remove = dw_wdt_drv_remove,
	.driver = {
	.name = "dw_wdt",
	.of_match_table = of_match_ptr(dw_wdt_of_match),
	.pm = &dw_wdt_pm_ops,
	},
	};

	module_platform_driver(dw_wdt_driver);

	MODULE_AUTHOR("Jamie Iles");
	MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
	MODULE_LICENSE("GPL");