drivers/watchdog/at32ap700x_wdt.c - third_party/linux - Git at Google

 /*
  * Watchdog driver for Atmel AT32AP700X devices
  *
  * Copyright (C) 2005-2006 Atmel Corporation
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  *
  *
  * Errata: WDT Clear is blocked after WDT Reset
  *
  * A watchdog timer event will, after reset, block writes to the WDT_CLEAR
  * register, preventing the program to clear the next Watchdog Timer Reset.
  *
  * If you still want to use the WDT after a WDT reset a small code can be
  * insterted at the startup checking the AVR32_PM.rcause register for WDT reset
  * and use a GPIO pin to reset the system. This method requires that one of the
  * GPIO pins are available and connected externally to the RESET_N pin. After
  * the GPIO pin has pulled down the reset line the GPIO will be reset and leave
  * the pin tristated with pullup.
  */

 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/miscdevice.h>
 #include <linux/fs.h>
 #include <linux/platform_device.h>
 #include <linux/watchdog.h>
 #include <linux/uaccess.h>
 #include <linux/io.h>
 #include <linux/spinlock.h>
 #include <linux/slab.h>

 #define TIMEOUT_MIN		1
 #define TIMEOUT_MAX		2
 #define TIMEOUT_DEFAULT		TIMEOUT_MAX

 /* module parameters */
 static int timeout =  TIMEOUT_DEFAULT;
 module_param(timeout, int, 0);
 MODULE_PARM_DESC(timeout,
 		"Timeout value. Limited to be 1 or 2 seconds. (default="
 		__MODULE_STRING(TIMEOUT_DEFAULT) ")");

 static int nowayout = WATCHDOG_NOWAYOUT;
 module_param(nowayout, int, 0);
 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 		__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

 /* Watchdog registers and write/read macro */
 #define WDT_CTRL		0x00
 #define WDT_CTRL_EN		   0
 #define WDT_CTRL_PSEL		   8
 #define WDT_CTRL_KEY		  24

 #define WDT_CLR			0x04

 #define WDT_RCAUSE		0x10
 #define WDT_RCAUSE_POR		   0
 #define WDT_RCAUSE_EXT		   2
 #define WDT_RCAUSE_WDT		   3
 #define WDT_RCAUSE_JTAG		   4
 #define WDT_RCAUSE_SERP		   5

 #define WDT_BIT(name)		(1 << WDT_##name)
 #define WDT_BF(name, value)	((value) << WDT_##name)

 #define wdt_readl(dev, reg)				\
 	__raw_readl((dev)->regs + WDT_##reg)
 #define wdt_writel(dev, reg, value)			\
 	__raw_writel((value), (dev)->regs + WDT_##reg)

 struct wdt_at32ap700x {
 	void __iomem		*regs;
 	spinlock_t		io_lock;
 	int			timeout;
 	int			boot_status;
 	unsigned long		users;
 	struct miscdevice	miscdev;
 };

 static struct wdt_at32ap700x *wdt;
 static char expect_release;

 /*
  * Disable the watchdog.
  */
 static inline void at32_wdt_stop(void)
 {
 	unsigned long psel;

 	spin_lock(&wdt->io_lock);
 	psel = wdt_readl(wdt, CTRL) & WDT_BF(CTRL_PSEL, 0x0f);
 	wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0x55));
 	wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0xaa));
 	spin_unlock(&wdt->io_lock);
 }

 /*
  * Enable and reset the watchdog.
  */
 static inline void at32_wdt_start(void)
 {
 	/* 0xf is 2^16 divider = 2 sec, 0xe is 2^15 divider = 1 sec */
 	unsigned long psel = (wdt->timeout > 1) ? 0xf : 0xe;

 	spin_lock(&wdt->io_lock);
 	wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
 			| WDT_BF(CTRL_PSEL, psel)
 			| WDT_BF(CTRL_KEY, 0x55));
 	wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
 			| WDT_BF(CTRL_PSEL, psel)
 			| WDT_BF(CTRL_KEY, 0xaa));
 	spin_unlock(&wdt->io_lock);
 }

 /*
  * Pat the watchdog timer.
  */
 static inline void at32_wdt_pat(void)
 {
 	spin_lock(&wdt->io_lock);
 	wdt_writel(wdt, CLR, 0x42);
 	spin_unlock(&wdt->io_lock);
 }

 /*
  * Watchdog device is opened, and watchdog starts running.
  */
 static int at32_wdt_open(struct inode *inode, struct file *file)
 {
 	if (test_and_set_bit(1, &wdt->users))
 		return -EBUSY;

 	at32_wdt_start();
 	return nonseekable_open(inode, file);
 }

 /*
  * Close the watchdog device.
  */
 static int at32_wdt_close(struct inode *inode, struct file *file)
 {
 	if (expect_release == 42) {
 		at32_wdt_stop();
 	} else {
 		dev_dbg(wdt->miscdev.parent,
 			"unexpected close, not stopping watchdog!\n");
 		at32_wdt_pat();
 	}
 	clear_bit(1, &wdt->users);
 	expect_release = 0;
 	return 0;
 }

 /*
  * Change the watchdog time interval.
  */
 static int at32_wdt_settimeout(int time)
 {
 	/*
 	 * All counting occurs at 1 / SLOW_CLOCK (32 kHz) and max prescaler is
 	 * 2 ^ 16 allowing up to 2 seconds timeout.
 	 */
 	if ((time < TIMEOUT_MIN) || (time > TIMEOUT_MAX))
 		return -EINVAL;

 	/*
 	 * Set new watchdog time. It will be used when at32_wdt_start() is
 	 * called.
 	 */
 	wdt->timeout = time;
 	return 0;
 }

 /*
  * Get the watchdog status.
  */
 static int at32_wdt_get_status(void)
 {
 	int rcause;
 	int status = 0;

 	rcause = wdt_readl(wdt, RCAUSE);

 	switch (rcause) {
 	case WDT_BIT(RCAUSE_EXT):
 		status = WDIOF_EXTERN1;
 		break;
 	case WDT_BIT(RCAUSE_WDT):
 		status = WDIOF_CARDRESET;
 		break;
 	case WDT_BIT(RCAUSE_POR):  /* fall through */
 	case WDT_BIT(RCAUSE_JTAG): /* fall through */
 	case WDT_BIT(RCAUSE_SERP): /* fall through */
 	default:
 		break;
 	}

 	return status;
 }

 static const struct watchdog_info at32_wdt_info = {
 	.identity	= "at32ap700x watchdog",
 	.options	= WDIOF_SETTIMEOUT |
 			  WDIOF_KEEPALIVEPING |
 			  WDIOF_MAGICCLOSE,
 };

 /*
  * Handle commands from user-space.
  */
 static long at32_wdt_ioctl(struct file *file,
 				unsigned int cmd, unsigned long arg)
 {
 	int ret = -ENOTTY;
 	int time;
 	void __user *argp = (void __user *)arg;
 	int __user *p = argp;

 	switch (cmd) {
 	case WDIOC_GETSUPPORT:
 		ret = copy_to_user(argp, &at32_wdt_info,
 				sizeof(at32_wdt_info)) ? -EFAULT : 0;
 		break;
 	case WDIOC_GETSTATUS:
 		ret = put_user(0, p);
 		break;
 	case WDIOC_GETBOOTSTATUS:
 		ret = put_user(wdt->boot_status, p);
 		break;
 	case WDIOC_SETOPTIONS:
 		ret = get_user(time, p);
 		if (ret)
 			break;
 		if (time & WDIOS_DISABLECARD)
 			at32_wdt_stop();
 		if (time & WDIOS_ENABLECARD)
 			at32_wdt_start();
 		ret = 0;
 		break;
 	case WDIOC_KEEPALIVE:
 		at32_wdt_pat();
 		ret = 0;
 		break;
 	case WDIOC_SETTIMEOUT:
 		ret = get_user(time, p);
 		if (ret)
 			break;
 		ret = at32_wdt_settimeout(time);
 		if (ret)
 			break;
 		/* Enable new time value */
 		at32_wdt_start();
 		/* fall through */
 	case WDIOC_GETTIMEOUT:
 		ret = put_user(wdt->timeout, p);
 		break;
 	}

 	return ret;
 }

 static ssize_t at32_wdt_write(struct file *file, const char __user *data,
 				size_t len, loff_t *ppos)
 {
 	/* See if we got the magic character 'V' and reload the timer */
 	if (len) {
 		if (!nowayout) {
 			size_t i;

 			/*
 			 * note: just in case someone wrote the magic
 			 * character five months ago...
 			 */
 			expect_release = 0;

 			/*
 			 * scan to see whether or not we got the magic
 			 * character
 			 */
 			for (i = 0; i != len; i++) {
 				char c;
 				if (get_user(c, data + i))
 					return -EFAULT;
 				if (c == 'V')
 					expect_release = 42;
 			}
 		}
 		/* someone wrote to us, we should pat the watchdog */
 		at32_wdt_pat();
 	}
 	return len;
 }

 static const struct file_operations at32_wdt_fops = {
 	.owner		= THIS_MODULE,
 	.llseek		= no_llseek,
 	.unlocked_ioctl	= at32_wdt_ioctl,
 	.open		= at32_wdt_open,
 	.release	= at32_wdt_close,
 	.write		= at32_wdt_write,
 };

 static int __init at32_wdt_probe(struct platform_device *pdev)
 {
 	struct resource	*regs;
 	int ret;

 	if (wdt) {
 		dev_dbg(&pdev->dev, "only 1 wdt instance supported.\n");
 		return -EBUSY;
 	}

 	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!regs) {
 		dev_dbg(&pdev->dev, "missing mmio resource\n");
 		return -ENXIO;
 	}

 	wdt = kzalloc(sizeof(struct wdt_at32ap700x), GFP_KERNEL);
 	if (!wdt) {
 		dev_dbg(&pdev->dev, "no memory for wdt structure\n");
 		return -ENOMEM;
 	}

 	wdt->regs = ioremap(regs->start, resource_size(regs));
 	if (!wdt->regs) {
 		ret = -ENOMEM;
 		dev_dbg(&pdev->dev, "could not map I/O memory\n");
 		goto err_free;
 	}

 	spin_lock_init(&wdt->io_lock);
 	wdt->boot_status = at32_wdt_get_status();

 	/* Work-around for watchdog silicon errata. */
 	if (wdt->boot_status & WDIOF_CARDRESET) {
 		dev_info(&pdev->dev, "CPU must be reset with external "
 				"reset or POR due to silicon errata.\n");
 		ret = -EIO;
 		goto err_iounmap;
 	} else {
 		wdt->users = 0;
 	}

 	wdt->miscdev.minor	= WATCHDOG_MINOR;
 	wdt->miscdev.name	= "watchdog";
 	wdt->miscdev.fops	= &at32_wdt_fops;
 	wdt->miscdev.parent	= &pdev->dev;

 	platform_set_drvdata(pdev, wdt);

 	if (at32_wdt_settimeout(timeout)) {
 		at32_wdt_settimeout(TIMEOUT_DEFAULT);
 		dev_dbg(&pdev->dev,
 			"default timeout invalid, set to %d sec.\n",
 			TIMEOUT_DEFAULT);
 	}

 	ret = misc_register(&wdt->miscdev);
 	if (ret) {
 		dev_dbg(&pdev->dev, "failed to register wdt miscdev\n");
 		goto err_register;
 	}

 	dev_info(&pdev->dev,
 		"AT32AP700X WDT at 0x%p, timeout %d sec (nowayout=%d)\n",
 		wdt->regs, wdt->timeout, nowayout);

 	return 0;

 err_register:
 	platform_set_drvdata(pdev, NULL);
 err_iounmap:
 	iounmap(wdt->regs);
 err_free:
 	kfree(wdt);
 	wdt = NULL;
 	return ret;
 }

 static int __exit at32_wdt_remove(struct platform_device *pdev)
 {
 	if (wdt && platform_get_drvdata(pdev) == wdt) {
 		/* Stop the timer before we leave */
 		if (!nowayout)
 			at32_wdt_stop();

 		misc_deregister(&wdt->miscdev);
 		iounmap(wdt->regs);
 		kfree(wdt);
 		wdt = NULL;
 		platform_set_drvdata(pdev, NULL);
 	}
 	return 0;
 }

 static void at32_wdt_shutdown(struct platform_device *pdev)
 {
 	at32_wdt_stop();
 }

 #ifdef CONFIG_PM
 static int at32_wdt_suspend(struct platform_device *pdev, pm_message_t message)
 {
 	at32_wdt_stop();
 	return 0;
 }

 static int at32_wdt_resume(struct platform_device *pdev)
 {
 	if (wdt->users)
 		at32_wdt_start();
 	return 0;
 }
 #else
 #define at32_wdt_suspend NULL
 #define at32_wdt_resume NULL
 #endif

 /* work with hotplug and coldplug */
 MODULE_ALIAS("platform:at32_wdt");

 static struct platform_driver at32_wdt_driver = {
 	.remove		= __exit_p(at32_wdt_remove),
 	.suspend	= at32_wdt_suspend,
 	.resume		= at32_wdt_resume,
 	.driver		= {
 		.name	= "at32_wdt",
 		.owner	= THIS_MODULE,
 	},
 	.shutdown	= at32_wdt_shutdown,
 };

 static int __init at32_wdt_init(void)
 {
 	return platform_driver_probe(&at32_wdt_driver, at32_wdt_probe);
 }
 module_init(at32_wdt_init);

 static void __exit at32_wdt_exit(void)
 {
 	platform_driver_unregister(&at32_wdt_driver);
 }
 module_exit(at32_wdt_exit);

 MODULE_AUTHOR("Hans-Christian Egtvedt <egtvedt@samfundet.no>");
 MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
	/*
	* Watchdog driver for Atmel AT32AP700X devices
	*
	* Copyright (C) 2005-2006 Atmel Corporation
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*
	*
	* Errata: WDT Clear is blocked after WDT Reset
	*
	* A watchdog timer event will, after reset, block writes to the WDT_CLEAR
	* register, preventing the program to clear the next Watchdog Timer Reset.
	*
	* If you still want to use the WDT after a WDT reset a small code can be
	* insterted at the startup checking the AVR32_PM.rcause register for WDT reset
	* and use a GPIO pin to reset the system. This method requires that one of the
	* GPIO pins are available and connected externally to the RESET_N pin. After
	* the GPIO pin has pulled down the reset line the GPIO will be reset and leave
	* the pin tristated with pullup.
	*/

	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/miscdevice.h>
	#include <linux/fs.h>
	#include <linux/platform_device.h>
	#include <linux/watchdog.h>
	#include <linux/uaccess.h>
	#include <linux/io.h>
	#include <linux/spinlock.h>
	#include <linux/slab.h>

	#define TIMEOUT_MIN 1
	#define TIMEOUT_MAX 2
	#define TIMEOUT_DEFAULT TIMEOUT_MAX

	/* module parameters */
	static int timeout = TIMEOUT_DEFAULT;
	module_param(timeout, int, 0);
	MODULE_PARM_DESC(timeout,
	"Timeout value. Limited to be 1 or 2 seconds. (default="
	__MODULE_STRING(TIMEOUT_DEFAULT) ")");

	static int nowayout = WATCHDOG_NOWAYOUT;
	module_param(nowayout, int, 0);
	MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

	/* Watchdog registers and write/read macro */
	#define WDT_CTRL 0x00
	#define WDT_CTRL_EN 0
	#define WDT_CTRL_PSEL 8
	#define WDT_CTRL_KEY 24

	#define WDT_CLR 0x04

	#define WDT_RCAUSE 0x10
	#define WDT_RCAUSE_POR 0
	#define WDT_RCAUSE_EXT 2
	#define WDT_RCAUSE_WDT 3
	#define WDT_RCAUSE_JTAG 4
	#define WDT_RCAUSE_SERP 5

	#define WDT_BIT(name) (1 << WDT_##name)
	#define WDT_BF(name, value) ((value) << WDT_##name)

	#define wdt_readl(dev, reg) \
	__raw_readl((dev)->regs + WDT_##reg)
	#define wdt_writel(dev, reg, value) \
	__raw_writel((value), (dev)->regs + WDT_##reg)

	struct wdt_at32ap700x {
	void __iomem *regs;
	spinlock_t io_lock;
	int timeout;
	int boot_status;
	unsigned long users;
	struct miscdevice miscdev;
	};

	static struct wdt_at32ap700x *wdt;
	static char expect_release;

	/*
	* Disable the watchdog.
	*/
	static inline void at32_wdt_stop(void)
	{
	unsigned long psel;

	spin_lock(&wdt->io_lock);
	psel = wdt_readl(wdt, CTRL) & WDT_BF(CTRL_PSEL, 0x0f);
	wdt_writel(wdt, CTRL, psel \| WDT_BF(CTRL_KEY, 0x55));
	wdt_writel(wdt, CTRL, psel \| WDT_BF(CTRL_KEY, 0xaa));
	spin_unlock(&wdt->io_lock);
	}

	/*
	* Enable and reset the watchdog.
	*/
	static inline void at32_wdt_start(void)
	{
	/* 0xf is 2^16 divider = 2 sec, 0xe is 2^15 divider = 1 sec */
	unsigned long psel = (wdt->timeout > 1) ? 0xf : 0xe;

	spin_lock(&wdt->io_lock);
	wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
	\| WDT_BF(CTRL_PSEL, psel)
	\| WDT_BF(CTRL_KEY, 0x55));
	wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
	\| WDT_BF(CTRL_PSEL, psel)
	\| WDT_BF(CTRL_KEY, 0xaa));
	spin_unlock(&wdt->io_lock);
	}

	/*
	* Pat the watchdog timer.
	*/
	static inline void at32_wdt_pat(void)
	{
	spin_lock(&wdt->io_lock);
	wdt_writel(wdt, CLR, 0x42);
	spin_unlock(&wdt->io_lock);
	}

	/*
	* Watchdog device is opened, and watchdog starts running.
	*/
	static int at32_wdt_open(struct inode inode, struct file file)
	{
	if (test_and_set_bit(1, &wdt->users))
	return -EBUSY;

	at32_wdt_start();
	return nonseekable_open(inode, file);
	}

	/*
	* Close the watchdog device.
	*/
	static int at32_wdt_close(struct inode inode, struct file file)
	{
	if (expect_release == 42) {
	at32_wdt_stop();
	} else {
	dev_dbg(wdt->miscdev.parent,
	"unexpected close, not stopping watchdog!\n");
	at32_wdt_pat();
	}
	clear_bit(1, &wdt->users);
	expect_release = 0;
	return 0;
	}

	/*
	* Change the watchdog time interval.
	*/
	static int at32_wdt_settimeout(int time)
	{
	/*
	* All counting occurs at 1 / SLOW_CLOCK (32 kHz) and max prescaler is
	* 2 ^ 16 allowing up to 2 seconds timeout.
	*/
	if ((time < TIMEOUT_MIN) \|\| (time > TIMEOUT_MAX))
	return -EINVAL;

	/*
	* Set new watchdog time. It will be used when at32_wdt_start() is
	* called.
	*/
	wdt->timeout = time;
	return 0;
	}

	/*
	* Get the watchdog status.
	*/
	static int at32_wdt_get_status(void)
	{
	int rcause;
	int status = 0;

	rcause = wdt_readl(wdt, RCAUSE);

	switch (rcause) {
	case WDT_BIT(RCAUSE_EXT):
	status = WDIOF_EXTERN1;
	break;
	case WDT_BIT(RCAUSE_WDT):
	status = WDIOF_CARDRESET;
	break;
	case WDT_BIT(RCAUSE_POR): /* fall through */
	case WDT_BIT(RCAUSE_JTAG): /* fall through */
	case WDT_BIT(RCAUSE_SERP): /* fall through */
	default:
	break;
	}

	return status;
	}

	static const struct watchdog_info at32_wdt_info = {
	.identity = "at32ap700x watchdog",
	.options = WDIOF_SETTIMEOUT \|
	WDIOF_KEEPALIVEPING \|
	WDIOF_MAGICCLOSE,
	};

	/*
	* Handle commands from user-space.
	*/
	static long at32_wdt_ioctl(struct file *file,
	unsigned int cmd, unsigned long arg)
	{
	int ret = -ENOTTY;
	int time;
	void __user argp = (void __user )arg;
	int __user *p = argp;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
	ret = copy_to_user(argp, &at32_wdt_info,
	sizeof(at32_wdt_info)) ? -EFAULT : 0;
	break;
	case WDIOC_GETSTATUS:
	ret = put_user(0, p);
	break;
	case WDIOC_GETBOOTSTATUS:
	ret = put_user(wdt->boot_status, p);
	break;
	case WDIOC_SETOPTIONS:
	ret = get_user(time, p);
	if (ret)
	break;
	if (time & WDIOS_DISABLECARD)
	at32_wdt_stop();
	if (time & WDIOS_ENABLECARD)
	at32_wdt_start();
	ret = 0;
	break;
	case WDIOC_KEEPALIVE:
	at32_wdt_pat();
	ret = 0;
	break;
	case WDIOC_SETTIMEOUT:
	ret = get_user(time, p);
	if (ret)
	break;
	ret = at32_wdt_settimeout(time);
	if (ret)
	break;
	/* Enable new time value */
	at32_wdt_start();
	/* fall through */
	case WDIOC_GETTIMEOUT:
	ret = put_user(wdt->timeout, p);
	break;
	}

	return ret;
	}

	static ssize_t at32_wdt_write(struct file file, const char __user data,
	size_t len, loff_t *ppos)
	{
	/* See if we got the magic character 'V' and reload the timer */
	if (len) {
	if (!nowayout) {
	size_t i;

	/*
	* note: just in case someone wrote the magic
	* character five months ago...
	*/
	expect_release = 0;

	/*
	* scan to see whether or not we got the magic
	* character
	*/
	for (i = 0; i != len; i++) {
	char c;
	if (get_user(c, data + i))
	return -EFAULT;
	if (c == 'V')
	expect_release = 42;
	}
	}
	/* someone wrote to us, we should pat the watchdog */
	at32_wdt_pat();
	}
	return len;
	}

	static const struct file_operations at32_wdt_fops = {
	.owner = THIS_MODULE,
	.llseek = no_llseek,
	.unlocked_ioctl = at32_wdt_ioctl,
	.open = at32_wdt_open,
	.release = at32_wdt_close,
	.write = at32_wdt_write,
	};

	static int __init at32_wdt_probe(struct platform_device *pdev)
	{
	struct resource *regs;
	int ret;

	if (wdt) {
	dev_dbg(&pdev->dev, "only 1 wdt instance supported.\n");
	return -EBUSY;
	}

	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!regs) {
	dev_dbg(&pdev->dev, "missing mmio resource\n");
	return -ENXIO;
	}

	wdt = kzalloc(sizeof(struct wdt_at32ap700x), GFP_KERNEL);
	if (!wdt) {
	dev_dbg(&pdev->dev, "no memory for wdt structure\n");
	return -ENOMEM;
	}

	wdt->regs = ioremap(regs->start, resource_size(regs));
	if (!wdt->regs) {
	ret = -ENOMEM;
	dev_dbg(&pdev->dev, "could not map I/O memory\n");
	goto err_free;
	}

	spin_lock_init(&wdt->io_lock);
	wdt->boot_status = at32_wdt_get_status();

	/* Work-around for watchdog silicon errata. */
	if (wdt->boot_status & WDIOF_CARDRESET) {
	dev_info(&pdev->dev, "CPU must be reset with external "
	"reset or POR due to silicon errata.\n");
	ret = -EIO;
	goto err_iounmap;
	} else {
	wdt->users = 0;
	}

	wdt->miscdev.minor = WATCHDOG_MINOR;
	wdt->miscdev.name = "watchdog";
	wdt->miscdev.fops = &at32_wdt_fops;
	wdt->miscdev.parent = &pdev->dev;

	platform_set_drvdata(pdev, wdt);

	if (at32_wdt_settimeout(timeout)) {
	at32_wdt_settimeout(TIMEOUT_DEFAULT);
	dev_dbg(&pdev->dev,
	"default timeout invalid, set to %d sec.\n",
	TIMEOUT_DEFAULT);
	}

	ret = misc_register(&wdt->miscdev);
	if (ret) {
	dev_dbg(&pdev->dev, "failed to register wdt miscdev\n");
	goto err_register;
	}

	dev_info(&pdev->dev,
	"AT32AP700X WDT at 0x%p, timeout %d sec (nowayout=%d)\n",
	wdt->regs, wdt->timeout, nowayout);

	return 0;

	err_register:
	platform_set_drvdata(pdev, NULL);
	err_iounmap:
	iounmap(wdt->regs);
	err_free:
	kfree(wdt);
	wdt = NULL;
	return ret;
	}

	static int __exit at32_wdt_remove(struct platform_device *pdev)
	{
	if (wdt && platform_get_drvdata(pdev) == wdt) {
	/* Stop the timer before we leave */
	if (!nowayout)
	at32_wdt_stop();

	misc_deregister(&wdt->miscdev);
	iounmap(wdt->regs);
	kfree(wdt);
	wdt = NULL;
	platform_set_drvdata(pdev, NULL);
	}
	return 0;
	}

	static void at32_wdt_shutdown(struct platform_device *pdev)
	{
	at32_wdt_stop();
	}

	#ifdef CONFIG_PM
	static int at32_wdt_suspend(struct platform_device *pdev, pm_message_t message)
	{
	at32_wdt_stop();
	return 0;
	}

	static int at32_wdt_resume(struct platform_device *pdev)
	{
	if (wdt->users)
	at32_wdt_start();
	return 0;
	}
	#else
	#define at32_wdt_suspend NULL
	#define at32_wdt_resume NULL
	#endif

	/* work with hotplug and coldplug */
	MODULE_ALIAS("platform:at32_wdt");

	static struct platform_driver at32_wdt_driver = {
	.remove = __exit_p(at32_wdt_remove),
	.suspend = at32_wdt_suspend,
	.resume = at32_wdt_resume,
	.driver = {
	.name = "at32_wdt",
	.owner = THIS_MODULE,
	},
	.shutdown = at32_wdt_shutdown,
	};

	static int __init at32_wdt_init(void)
	{
	return platform_driver_probe(&at32_wdt_driver, at32_wdt_probe);
	}
	module_init(at32_wdt_init);

	static void __exit at32_wdt_exit(void)
	{
	platform_driver_unregister(&at32_wdt_driver);
	}
	module_exit(at32_wdt_exit);

	MODULE_AUTHOR("Hans-Christian Egtvedt <egtvedt@samfundet.no>");
	MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);