drivers/watchdog/wm831x_wdt.c - kernel/prism - Git at Google

 /*
  * Watchdog driver for the wm831x PMICs
  *
  * Copyright (C) 2009 Wolfson Microelectronics
  *
  * 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
  */

 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/fs.h>
 #include <linux/miscdevice.h>
 #include <linux/platform_device.h>
 #include <linux/watchdog.h>
 #include <linux/uaccess.h>
 #include <linux/gpio.h>

 #include <linux/mfd/wm831x/core.h>
 #include <linux/mfd/wm831x/pdata.h>
 #include <linux/mfd/wm831x/watchdog.h>

 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) ")");

 static unsigned long wm831x_wdt_users;
 static struct miscdevice wm831x_wdt_miscdev;
 static int wm831x_wdt_expect_close;
 static DEFINE_MUTEX(wdt_mutex);
 static struct wm831x *wm831x;
 static unsigned int update_gpio;
 static unsigned int update_state;

 /* We can't use the sub-second values here but they're included
  * for completeness.  */
 static struct {
 	int time;  /* Seconds */
 	u16 val;   /* WDOG_TO value */
 } wm831x_wdt_cfgs[] = {
 	{  1, 2 },
 	{  2, 3 },
 	{  4, 4 },
 	{  8, 5 },
 	{ 16, 6 },
 	{ 32, 7 },
 	{ 33, 7 },  /* Actually 32.768s so include both, others round down */
 };

 static int wm831x_wdt_set_timeout(struct wm831x *wm831x, u16 value)
 {
 	int ret;

 	mutex_lock(&wdt_mutex);

 	ret = wm831x_reg_unlock(wm831x);
 	if (ret == 0) {
 		ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
 				      WM831X_WDOG_TO_MASK, value);
 		wm831x_reg_lock(wm831x);
 	} else {
 		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
 			ret);
 	}

 	mutex_unlock(&wdt_mutex);

 	return ret;
 }

 static int wm831x_wdt_start(struct wm831x *wm831x)
 {
 	int ret;

 	mutex_lock(&wdt_mutex);

 	ret = wm831x_reg_unlock(wm831x);
 	if (ret == 0) {
 		ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
 				      WM831X_WDOG_ENA, WM831X_WDOG_ENA);
 		wm831x_reg_lock(wm831x);
 	} else {
 		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
 			ret);
 	}

 	mutex_unlock(&wdt_mutex);

 	return ret;
 }

 static int wm831x_wdt_stop(struct wm831x *wm831x)
 {
 	int ret;

 	mutex_lock(&wdt_mutex);

 	ret = wm831x_reg_unlock(wm831x);
 	if (ret == 0) {
 		ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
 				      WM831X_WDOG_ENA, 0);
 		wm831x_reg_lock(wm831x);
 	} else {
 		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
 			ret);
 	}

 	mutex_unlock(&wdt_mutex);

 	return ret;
 }

 static int wm831x_wdt_kick(struct wm831x *wm831x)
 {
 	int ret;
 	u16 reg;

 	mutex_lock(&wdt_mutex);

 	if (update_gpio) {
 		gpio_set_value_cansleep(update_gpio, update_state);
 		update_state = !update_state;
 		ret = 0;
 		goto out;
 	}


 	reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);

 	if (!(reg & WM831X_WDOG_RST_SRC)) {
 		dev_err(wm831x->dev, "Hardware watchdog update unsupported\n");
 		ret = -EINVAL;
 		goto out;
 	}

 	reg |= WM831X_WDOG_RESET;

 	ret = wm831x_reg_unlock(wm831x);
 	if (ret == 0) {
 		ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
 		wm831x_reg_lock(wm831x);
 	} else {
 		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
 			ret);
 	}

 out:
 	mutex_unlock(&wdt_mutex);

 	return ret;
 }

 static int wm831x_wdt_open(struct inode *inode, struct file *file)
 {
 	int ret;

 	if (!wm831x)
 		return -ENODEV;

 	if (test_and_set_bit(0, &wm831x_wdt_users))
 		return -EBUSY;

 	ret = wm831x_wdt_start(wm831x);
 	if (ret != 0)
 		return ret;

 	return nonseekable_open(inode, file);
 }

 static int wm831x_wdt_release(struct inode *inode, struct file *file)
 {
 	if (wm831x_wdt_expect_close)
 		wm831x_wdt_stop(wm831x);
 	else {
 		dev_warn(wm831x->dev, "Watchdog device closed uncleanly\n");
 		wm831x_wdt_kick(wm831x);
 	}

 	clear_bit(0, &wm831x_wdt_users);

 	return 0;
 }

 static ssize_t wm831x_wdt_write(struct file *file,
 				const char __user *data, size_t count,
 				loff_t *ppos)
 {
 	size_t i;

 	if (count) {
 		wm831x_wdt_kick(wm831x);

 		if (!nowayout) {
 			/* In case it was set long ago */
 			wm831x_wdt_expect_close = 0;

 			/* scan to see whether or not we got the magic
 			   character */
 			for (i = 0; i != count; i++) {
 				char c;
 				if (get_user(c, data + i))
 					return -EFAULT;
 				if (c == 'V')
 					wm831x_wdt_expect_close = 42;
 			}
 		}
 	}
 	return count;
 }

 static struct watchdog_info ident = {
 	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 	.identity = "WM831x Watchdog",
 };

 static long wm831x_wdt_ioctl(struct file *file, unsigned int cmd,
 			     unsigned long arg)
 {
 	int ret = -ENOTTY, time, i;
 	void __user *argp = (void __user *)arg;
 	int __user *p = argp;
 	u16 reg;

 	switch (cmd) {
 	case WDIOC_GETSUPPORT:
 		ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 		break;

 	case WDIOC_GETSTATUS:
 	case WDIOC_GETBOOTSTATUS:
 		ret = put_user(0, p);
 		break;

 	case WDIOC_SETOPTIONS:
 	{
 		int options;

 		if (get_user(options, p))
 			return -EFAULT;

 		ret = -EINVAL;

 		/* Setting both simultaneously means at least one must fail */
 		if (options == WDIOS_DISABLECARD)
 			ret = wm831x_wdt_start(wm831x);

 		if (options == WDIOS_ENABLECARD)
 			ret = wm831x_wdt_stop(wm831x);
 		break;
 	}

 	case WDIOC_KEEPALIVE:
 		ret = wm831x_wdt_kick(wm831x);
 		break;

 	case WDIOC_SETTIMEOUT:
 		ret = get_user(time, p);
 		if (ret)
 			break;

 		if (time == 0) {
 			if (nowayout)
 				ret = -EINVAL;
 			else
 				wm831x_wdt_stop(wm831x);
 			break;
 		}

 		for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
 			if (wm831x_wdt_cfgs[i].time == time)
 				break;
 		if (i == ARRAY_SIZE(wm831x_wdt_cfgs))
 			ret = -EINVAL;
 		else
 			ret = wm831x_wdt_set_timeout(wm831x,
 						     wm831x_wdt_cfgs[i].val);
 		break;

 	case WDIOC_GETTIMEOUT:
 		reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
 		reg &= WM831X_WDOG_TO_MASK;
 		for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
 			if (wm831x_wdt_cfgs[i].val == reg)
 				break;
 		if (i == ARRAY_SIZE(wm831x_wdt_cfgs)) {
 			dev_warn(wm831x->dev,
 				 "Unknown watchdog configuration: %x\n", reg);
 			ret = -EINVAL;
 		} else
 			ret = put_user(wm831x_wdt_cfgs[i].time, p);

 	}

 	return ret;
 }

 static const struct file_operations wm831x_wdt_fops = {
 	.owner = THIS_MODULE,
 	.llseek = no_llseek,
 	.write = wm831x_wdt_write,
 	.unlocked_ioctl = wm831x_wdt_ioctl,
 	.open = wm831x_wdt_open,
 	.release = wm831x_wdt_release,
 };

 static struct miscdevice wm831x_wdt_miscdev = {
 	.minor = WATCHDOG_MINOR,
 	.name = "watchdog",
 	.fops = &wm831x_wdt_fops,
 };

 static int __devinit wm831x_wdt_probe(struct platform_device *pdev)
 {
 	struct wm831x_pdata *chip_pdata;
 	struct wm831x_watchdog_pdata *pdata;
 	int reg, ret;

 	wm831x = dev_get_drvdata(pdev->dev.parent);

 	ret = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
 	if (ret < 0) {
 		dev_err(wm831x->dev, "Failed to read watchdog status: %d\n",
 			ret);
 		goto err;
 	}
 	reg = ret;

 	if (reg & WM831X_WDOG_DEBUG)
 		dev_warn(wm831x->dev, "Watchdog is paused\n");

 	/* Apply any configuration */
 	if (pdev->dev.parent->platform_data) {
 		chip_pdata = pdev->dev.parent->platform_data;
 		pdata = chip_pdata->watchdog;
 	} else {
 		pdata = NULL;
 	}

 	if (pdata) {
 		reg &= ~(WM831X_WDOG_SECACT_MASK | WM831X_WDOG_PRIMACT_MASK |
 			 WM831X_WDOG_RST_SRC);

 		reg |= pdata->primary << WM831X_WDOG_PRIMACT_SHIFT;
 		reg |= pdata->secondary << WM831X_WDOG_SECACT_SHIFT;
 		reg |= pdata->software << WM831X_WDOG_RST_SRC_SHIFT;

 		if (pdata->update_gpio) {
 			ret = gpio_request(pdata->update_gpio,
 					   "Watchdog update");
 			if (ret < 0) {
 				dev_err(wm831x->dev,
 					"Failed to request update GPIO: %d\n",
 					ret);
 				goto err;
 			}

 			ret = gpio_direction_output(pdata->update_gpio, 0);
 			if (ret != 0) {
 				dev_err(wm831x->dev,
 					"gpio_direction_output returned: %d\n",
 					ret);
 				goto err_gpio;
 			}

 			update_gpio = pdata->update_gpio;

 			/* Make sure the watchdog takes hardware updates */
 			reg |= WM831X_WDOG_RST_SRC;
 		}

 		ret = wm831x_reg_unlock(wm831x);
 		if (ret == 0) {
 			ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
 			wm831x_reg_lock(wm831x);
 		} else {
 			dev_err(wm831x->dev,
 				"Failed to unlock security key: %d\n", ret);
 			goto err_gpio;
 		}
 	}

 	wm831x_wdt_miscdev.parent = &pdev->dev;

 	ret = misc_register(&wm831x_wdt_miscdev);
 	if (ret != 0) {
 		dev_err(wm831x->dev, "Failed to register miscdev: %d\n", ret);
 		goto err_gpio;
 	}

 	return 0;

 err_gpio:
 	if (update_gpio) {
 		gpio_free(update_gpio);
 		update_gpio = 0;
 	}
 err:
 	return ret;
 }

 static int __devexit wm831x_wdt_remove(struct platform_device *pdev)
 {
 	if (update_gpio) {
 		gpio_free(update_gpio);
 		update_gpio = 0;
 	}

 	misc_deregister(&wm831x_wdt_miscdev);

 	return 0;
 }

 static struct platform_driver wm831x_wdt_driver = {
 	.probe = wm831x_wdt_probe,
 	.remove = __devexit_p(wm831x_wdt_remove),
 	.driver = {
 		.name = "wm831x-watchdog",
 	},
 };

 static int __init wm831x_wdt_init(void)
 {
 	return platform_driver_register(&wm831x_wdt_driver);
 }
 module_init(wm831x_wdt_init);

 static void __exit wm831x_wdt_exit(void)
 {
 	platform_driver_unregister(&wm831x_wdt_driver);
 }
 module_exit(wm831x_wdt_exit);

 MODULE_AUTHOR("Mark Brown");
 MODULE_DESCRIPTION("WM831x Watchdog");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:wm831x-watchdog");
	/*
	* Watchdog driver for the wm831x PMICs
	*
	* Copyright (C) 2009 Wolfson Microelectronics
	*
	* 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
	*/

	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/types.h>
	#include <linux/kernel.h>
	#include <linux/fs.h>
	#include <linux/miscdevice.h>
	#include <linux/platform_device.h>
	#include <linux/watchdog.h>
	#include <linux/uaccess.h>
	#include <linux/gpio.h>

	#include <linux/mfd/wm831x/core.h>
	#include <linux/mfd/wm831x/pdata.h>
	#include <linux/mfd/wm831x/watchdog.h>

	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) ")");

	static unsigned long wm831x_wdt_users;
	static struct miscdevice wm831x_wdt_miscdev;
	static int wm831x_wdt_expect_close;
	static DEFINE_MUTEX(wdt_mutex);
	static struct wm831x *wm831x;
	static unsigned int update_gpio;
	static unsigned int update_state;

	/* We can't use the sub-second values here but they're included
	* for completeness. */
	static struct {
	int time; /* Seconds */
	u16 val; /* WDOG_TO value */
	} wm831x_wdt_cfgs[] = {
	{ 1, 2 },
	{ 2, 3 },
	{ 4, 4 },
	{ 8, 5 },
	{ 16, 6 },
	{ 32, 7 },
	{ 33, 7 }, /* Actually 32.768s so include both, others round down */
	};

	static int wm831x_wdt_set_timeout(struct wm831x *wm831x, u16 value)
	{
	int ret;

	mutex_lock(&wdt_mutex);

	ret = wm831x_reg_unlock(wm831x);
	if (ret == 0) {
	ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
	WM831X_WDOG_TO_MASK, value);
	wm831x_reg_lock(wm831x);
	} else {
	dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
	ret);
	}

	mutex_unlock(&wdt_mutex);

	return ret;
	}

	static int wm831x_wdt_start(struct wm831x *wm831x)
	{
	int ret;

	mutex_lock(&wdt_mutex);

	ret = wm831x_reg_unlock(wm831x);
	if (ret == 0) {
	ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
	WM831X_WDOG_ENA, WM831X_WDOG_ENA);
	wm831x_reg_lock(wm831x);
	} else {
	dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
	ret);
	}

	mutex_unlock(&wdt_mutex);

	return ret;
	}

	static int wm831x_wdt_stop(struct wm831x *wm831x)
	{
	int ret;

	mutex_lock(&wdt_mutex);

	ret = wm831x_reg_unlock(wm831x);
	if (ret == 0) {
	ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
	WM831X_WDOG_ENA, 0);
	wm831x_reg_lock(wm831x);
	} else {
	dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
	ret);
	}

	mutex_unlock(&wdt_mutex);

	return ret;
	}

	static int wm831x_wdt_kick(struct wm831x *wm831x)
	{
	int ret;
	u16 reg;

	mutex_lock(&wdt_mutex);

	if (update_gpio) {
	gpio_set_value_cansleep(update_gpio, update_state);
	update_state = !update_state;
	ret = 0;
	goto out;
	}


	reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);

	if (!(reg & WM831X_WDOG_RST_SRC)) {
	dev_err(wm831x->dev, "Hardware watchdog update unsupported\n");
	ret = -EINVAL;
	goto out;
	}

	reg \|= WM831X_WDOG_RESET;

	ret = wm831x_reg_unlock(wm831x);
	if (ret == 0) {
	ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
	wm831x_reg_lock(wm831x);
	} else {
	dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
	ret);
	}

	out:
	mutex_unlock(&wdt_mutex);

	return ret;
	}

	static int wm831x_wdt_open(struct inode inode, struct file file)
	{
	int ret;

	if (!wm831x)
	return -ENODEV;

	if (test_and_set_bit(0, &wm831x_wdt_users))
	return -EBUSY;

	ret = wm831x_wdt_start(wm831x);
	if (ret != 0)
	return ret;

	return nonseekable_open(inode, file);
	}

	static int wm831x_wdt_release(struct inode inode, struct file file)
	{
	if (wm831x_wdt_expect_close)
	wm831x_wdt_stop(wm831x);
	else {
	dev_warn(wm831x->dev, "Watchdog device closed uncleanly\n");
	wm831x_wdt_kick(wm831x);
	}

	clear_bit(0, &wm831x_wdt_users);

	return 0;
	}

	static ssize_t wm831x_wdt_write(struct file *file,
	const char __user *data, size_t count,
	loff_t *ppos)
	{
	size_t i;

	if (count) {
	wm831x_wdt_kick(wm831x);

	if (!nowayout) {
	/* In case it was set long ago */
	wm831x_wdt_expect_close = 0;

	/* scan to see whether or not we got the magic
	character */
	for (i = 0; i != count; i++) {
	char c;
	if (get_user(c, data + i))
	return -EFAULT;
	if (c == 'V')
	wm831x_wdt_expect_close = 42;
	}
	}
	}
	return count;
	}

	static struct watchdog_info ident = {
	.options = WDIOF_SETTIMEOUT \| WDIOF_KEEPALIVEPING \| WDIOF_MAGICCLOSE,
	.identity = "WM831x Watchdog",
	};

	static long wm831x_wdt_ioctl(struct file *file, unsigned int cmd,
	unsigned long arg)
	{
	int ret = -ENOTTY, time, i;
	void __user argp = (void __user )arg;
	int __user *p = argp;
	u16 reg;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
	ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
	break;

	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
	ret = put_user(0, p);
	break;

	case WDIOC_SETOPTIONS:
	{
	int options;

	if (get_user(options, p))
	return -EFAULT;

	ret = -EINVAL;

	/* Setting both simultaneously means at least one must fail */
	if (options == WDIOS_DISABLECARD)
	ret = wm831x_wdt_start(wm831x);

	if (options == WDIOS_ENABLECARD)
	ret = wm831x_wdt_stop(wm831x);
	break;
	}

	case WDIOC_KEEPALIVE:
	ret = wm831x_wdt_kick(wm831x);
	break;

	case WDIOC_SETTIMEOUT:
	ret = get_user(time, p);
	if (ret)
	break;

	if (time == 0) {
	if (nowayout)
	ret = -EINVAL;
	else
	wm831x_wdt_stop(wm831x);
	break;
	}

	for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
	if (wm831x_wdt_cfgs[i].time == time)
	break;
	if (i == ARRAY_SIZE(wm831x_wdt_cfgs))
	ret = -EINVAL;
	else
	ret = wm831x_wdt_set_timeout(wm831x,
	wm831x_wdt_cfgs[i].val);
	break;

	case WDIOC_GETTIMEOUT:
	reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
	reg &= WM831X_WDOG_TO_MASK;
	for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
	if (wm831x_wdt_cfgs[i].val == reg)
	break;
	if (i == ARRAY_SIZE(wm831x_wdt_cfgs)) {
	dev_warn(wm831x->dev,
	"Unknown watchdog configuration: %x\n", reg);
	ret = -EINVAL;
	} else
	ret = put_user(wm831x_wdt_cfgs[i].time, p);

	}

	return ret;
	}

	static const struct file_operations wm831x_wdt_fops = {
	.owner = THIS_MODULE,
	.llseek = no_llseek,
	.write = wm831x_wdt_write,
	.unlocked_ioctl = wm831x_wdt_ioctl,
	.open = wm831x_wdt_open,
	.release = wm831x_wdt_release,
	};

	static struct miscdevice wm831x_wdt_miscdev = {
	.minor = WATCHDOG_MINOR,
	.name = "watchdog",
	.fops = &wm831x_wdt_fops,
	};

	static int __devinit wm831x_wdt_probe(struct platform_device *pdev)
	{
	struct wm831x_pdata *chip_pdata;
	struct wm831x_watchdog_pdata *pdata;
	int reg, ret;

	wm831x = dev_get_drvdata(pdev->dev.parent);

	ret = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
	if (ret < 0) {
	dev_err(wm831x->dev, "Failed to read watchdog status: %d\n",
	ret);
	goto err;
	}
	reg = ret;

	if (reg & WM831X_WDOG_DEBUG)
	dev_warn(wm831x->dev, "Watchdog is paused\n");

	/* Apply any configuration */
	if (pdev->dev.parent->platform_data) {
	chip_pdata = pdev->dev.parent->platform_data;
	pdata = chip_pdata->watchdog;
	} else {
	pdata = NULL;
	}

	if (pdata) {
	reg &= ~(WM831X_WDOG_SECACT_MASK \| WM831X_WDOG_PRIMACT_MASK \|
	WM831X_WDOG_RST_SRC);

	reg \|= pdata->primary << WM831X_WDOG_PRIMACT_SHIFT;
	reg \|= pdata->secondary << WM831X_WDOG_SECACT_SHIFT;
	reg \|= pdata->software << WM831X_WDOG_RST_SRC_SHIFT;

	if (pdata->update_gpio) {
	ret = gpio_request(pdata->update_gpio,
	"Watchdog update");
	if (ret < 0) {
	dev_err(wm831x->dev,
	"Failed to request update GPIO: %d\n",
	ret);
	goto err;
	}

	ret = gpio_direction_output(pdata->update_gpio, 0);
	if (ret != 0) {
	dev_err(wm831x->dev,
	"gpio_direction_output returned: %d\n",
	ret);
	goto err_gpio;
	}

	update_gpio = pdata->update_gpio;

	/* Make sure the watchdog takes hardware updates */
	reg \|= WM831X_WDOG_RST_SRC;
	}

	ret = wm831x_reg_unlock(wm831x);
	if (ret == 0) {
	ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
	wm831x_reg_lock(wm831x);
	} else {
	dev_err(wm831x->dev,
	"Failed to unlock security key: %d\n", ret);
	goto err_gpio;
	}
	}

	wm831x_wdt_miscdev.parent = &pdev->dev;

	ret = misc_register(&wm831x_wdt_miscdev);
	if (ret != 0) {
	dev_err(wm831x->dev, "Failed to register miscdev: %d\n", ret);
	goto err_gpio;
	}

	return 0;

	err_gpio:
	if (update_gpio) {
	gpio_free(update_gpio);
	update_gpio = 0;
	}
	err:
	return ret;
	}

	static int __devexit wm831x_wdt_remove(struct platform_device *pdev)
	{
	if (update_gpio) {
	gpio_free(update_gpio);
	update_gpio = 0;
	}

	misc_deregister(&wm831x_wdt_miscdev);

	return 0;
	}

	static struct platform_driver wm831x_wdt_driver = {
	.probe = wm831x_wdt_probe,
	.remove = __devexit_p(wm831x_wdt_remove),
	.driver = {
	.name = "wm831x-watchdog",
	},
	};

	static int __init wm831x_wdt_init(void)
	{
	return platform_driver_register(&wm831x_wdt_driver);
	}
	module_init(wm831x_wdt_init);

	static void __exit wm831x_wdt_exit(void)
	{
	platform_driver_unregister(&wm831x_wdt_driver);
	}
	module_exit(wm831x_wdt_exit);

	MODULE_AUTHOR("Mark Brown");
	MODULE_DESCRIPTION("WM831x Watchdog");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:wm831x-watchdog");