drivers/watchdog/omap_wdt.c - arm/linux-arm64-legacy - Git at Google

 /*
  * omap_wdt.c
  *
  * Watchdog driver for the TI OMAP 16xx & 24xx/34xx 32KHz (non-secure) watchdog
  *
  * Author: MontaVista Software, Inc.
  *	 <gdavis@mvista.com> or <source@mvista.com>
  *
  * 2003 (c) MontaVista Software, Inc. 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.
  *
  * History:
  *
  * 20030527: George G. Davis <gdavis@mvista.com>
  *	Initially based on linux-2.4.19-rmk7-pxa1/drivers/char/sa1100_wdt.c
  *	(c) Copyright 2000 Oleg Drokin <green@crimea.edu>
  *	Based on SoftDog driver by Alan Cox <alan@lxorguk.ukuu.org.uk>
  *
  * Copyright (c) 2004 Texas Instruments.
  *	1. Modified to support OMAP1610 32-KHz watchdog timer
  *	2. Ported to 2.6 kernel
  *
  * Copyright (c) 2005 David Brownell
  *	Use the driver model and standard identifiers; handle bigger timeouts.
  */

 #include <linux/module.h>
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
 #include <linux/miscdevice.h>
 #include <linux/watchdog.h>
 #include <linux/reboot.h>
 #include <linux/init.h>
 #include <linux/err.h>
 #include <linux/platform_device.h>
 #include <linux/moduleparam.h>
 #include <linux/clk.h>
 #include <linux/bitops.h>
 #include <linux/io.h>
 #include <linux/uaccess.h>
 #include <linux/slab.h>
 #include <mach/hardware.h>
 #include <plat/prcm.h>

 #include "omap_wdt.h"

 static struct platform_device *omap_wdt_dev;

 static unsigned timer_margin;
 module_param(timer_margin, uint, 0);
 MODULE_PARM_DESC(timer_margin, "initial watchdog timeout (in seconds)");

 static unsigned int wdt_trgr_pattern = 0x1234;
 static spinlock_t wdt_lock;

 struct omap_wdt_dev {
 	void __iomem    *base;          /* physical */
 	struct device   *dev;
 	int             omap_wdt_users;
 	struct clk      *ick;
 	struct clk      *fck;
 	struct resource *mem;
 	struct miscdevice omap_wdt_miscdev;
 };

 static void omap_wdt_ping(struct omap_wdt_dev *wdev)
 {
 	void __iomem    *base = wdev->base;

 	/* wait for posted write to complete */
 	while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x08)
 		cpu_relax();

 	wdt_trgr_pattern = ~wdt_trgr_pattern;
 	__raw_writel(wdt_trgr_pattern, (base + OMAP_WATCHDOG_TGR));

 	/* wait for posted write to complete */
 	while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x08)
 		cpu_relax();
 	/* reloaded WCRR from WLDR */
 }

 static void omap_wdt_enable(struct omap_wdt_dev *wdev)
 {
 	void __iomem *base = wdev->base;

 	/* Sequence to enable the watchdog */
 	__raw_writel(0xBBBB, base + OMAP_WATCHDOG_SPR);
 	while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x10)
 		cpu_relax();

 	__raw_writel(0x4444, base + OMAP_WATCHDOG_SPR);
 	while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x10)
 		cpu_relax();
 }

 static void omap_wdt_disable(struct omap_wdt_dev *wdev)
 {
 	void __iomem *base = wdev->base;

 	/* sequence required to disable watchdog */
 	__raw_writel(0xAAAA, base + OMAP_WATCHDOG_SPR);	/* TIMER_MODE */
 	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x10)
 		cpu_relax();

 	__raw_writel(0x5555, base + OMAP_WATCHDOG_SPR);	/* TIMER_MODE */
 	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x10)
 		cpu_relax();
 }

 static void omap_wdt_adjust_timeout(unsigned new_timeout)
 {
 	if (new_timeout < TIMER_MARGIN_MIN)
 		new_timeout = TIMER_MARGIN_DEFAULT;
 	if (new_timeout > TIMER_MARGIN_MAX)
 		new_timeout = TIMER_MARGIN_MAX;
 	timer_margin = new_timeout;
 }

 static void omap_wdt_set_timeout(struct omap_wdt_dev *wdev)
 {
 	u32 pre_margin = GET_WLDR_VAL(timer_margin);
 	void __iomem *base = wdev->base;

 	/* just count up at 32 KHz */
 	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x04)
 		cpu_relax();

 	__raw_writel(pre_margin, base + OMAP_WATCHDOG_LDR);
 	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x04)
 		cpu_relax();
 }

 /*
  *	Allow only one task to hold it open
  */
 static int omap_wdt_open(struct inode *inode, struct file *file)
 {
 	struct omap_wdt_dev *wdev = platform_get_drvdata(omap_wdt_dev);
 	void __iomem *base = wdev->base;

 	if (test_and_set_bit(1, (unsigned long *)&(wdev->omap_wdt_users)))
 		return -EBUSY;

 	clk_enable(wdev->ick);    /* Enable the interface clock */
 	clk_enable(wdev->fck);    /* Enable the functional clock */

 	/* initialize prescaler */
 	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x01)
 		cpu_relax();

 	__raw_writel((1 << 5) | (PTV << 2), base + OMAP_WATCHDOG_CNTRL);
 	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x01)
 		cpu_relax();

 	file->private_data = (void *) wdev;

 	omap_wdt_set_timeout(wdev);
 	omap_wdt_ping(wdev); /* trigger loading of new timeout value */
 	omap_wdt_enable(wdev);

 	return nonseekable_open(inode, file);
 }

 static int omap_wdt_release(struct inode *inode, struct file *file)
 {
 	struct omap_wdt_dev *wdev = file->private_data;

 	/*
 	 *      Shut off the timer unless NOWAYOUT is defined.
 	 */
 #ifndef CONFIG_WATCHDOG_NOWAYOUT

 	omap_wdt_disable(wdev);

 	clk_disable(wdev->ick);
 	clk_disable(wdev->fck);
 #else
 	printk(KERN_CRIT "omap_wdt: Unexpected close, not stopping!\n");
 #endif
 	wdev->omap_wdt_users = 0;

 	return 0;
 }

 static ssize_t omap_wdt_write(struct file *file, const char __user *data,
 		size_t len, loff_t *ppos)
 {
 	struct omap_wdt_dev *wdev = file->private_data;

 	/* Refresh LOAD_TIME. */
 	if (len) {
 		spin_lock(&wdt_lock);
 		omap_wdt_ping(wdev);
 		spin_unlock(&wdt_lock);
 	}
 	return len;
 }

 static long omap_wdt_ioctl(struct file *file, unsigned int cmd,
 						unsigned long arg)
 {
 	struct omap_wdt_dev *wdev;
 	int new_margin;
 	static const struct watchdog_info ident = {
 		.identity = "OMAP Watchdog",
 		.options = WDIOF_SETTIMEOUT,
 		.firmware_version = 0,
 	};

 	wdev = file->private_data;

 	switch (cmd) {
 	case WDIOC_GETSUPPORT:
 		return copy_to_user((struct watchdog_info __user *)arg, &ident,
 				sizeof(ident));
 	case WDIOC_GETSTATUS:
 		return put_user(0, (int __user *)arg);
 	case WDIOC_GETBOOTSTATUS:
 		if (cpu_is_omap16xx())
 			return put_user(__raw_readw(ARM_SYSST),
 					(int __user *)arg);
 		if (cpu_is_omap24xx())
 			return put_user(omap_prcm_get_reset_sources(),
 					(int __user *)arg);
 	case WDIOC_KEEPALIVE:
 		spin_lock(&wdt_lock);
 		omap_wdt_ping(wdev);
 		spin_unlock(&wdt_lock);
 		return 0;
 	case WDIOC_SETTIMEOUT:
 		if (get_user(new_margin, (int __user *)arg))
 			return -EFAULT;
 		omap_wdt_adjust_timeout(new_margin);

 		spin_lock(&wdt_lock);
 		omap_wdt_disable(wdev);
 		omap_wdt_set_timeout(wdev);
 		omap_wdt_enable(wdev);

 		omap_wdt_ping(wdev);
 		spin_unlock(&wdt_lock);
 		/* Fall */
 	case WDIOC_GETTIMEOUT:
 		return put_user(timer_margin, (int __user *)arg);
 	default:
 		return -ENOTTY;
 	}
 }

 static const struct file_operations omap_wdt_fops = {
 	.owner = THIS_MODULE,
 	.write = omap_wdt_write,
 	.unlocked_ioctl = omap_wdt_ioctl,
 	.open = omap_wdt_open,
 	.release = omap_wdt_release,
 	.llseek = no_llseek,
 };

 static int __devinit omap_wdt_probe(struct platform_device *pdev)
 {
 	struct resource *res, *mem;
 	struct omap_wdt_dev *wdev;
 	int ret;

 	/* reserve static register mappings */
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res) {
 		ret = -ENOENT;
 		goto err_get_resource;
 	}

 	if (omap_wdt_dev) {
 		ret = -EBUSY;
 		goto err_busy;
 	}

 	mem = request_mem_region(res->start, resource_size(res), pdev->name);
 	if (!mem) {
 		ret = -EBUSY;
 		goto err_busy;
 	}

 	wdev = kzalloc(sizeof(struct omap_wdt_dev), GFP_KERNEL);
 	if (!wdev) {
 		ret = -ENOMEM;
 		goto err_kzalloc;
 	}

 	wdev->omap_wdt_users = 0;
 	wdev->mem = mem;

 	wdev->ick = clk_get(&pdev->dev, "ick");
 	if (IS_ERR(wdev->ick)) {
 		ret = PTR_ERR(wdev->ick);
 		wdev->ick = NULL;
 		goto err_clk;
 	}
 	wdev->fck = clk_get(&pdev->dev, "fck");
 	if (IS_ERR(wdev->fck)) {
 		ret = PTR_ERR(wdev->fck);
 		wdev->fck = NULL;
 		goto err_clk;
 	}

 	wdev->base = ioremap(res->start, resource_size(res));
 	if (!wdev->base) {
 		ret = -ENOMEM;
 		goto err_ioremap;
 	}

 	platform_set_drvdata(pdev, wdev);

 	clk_enable(wdev->ick);
 	clk_enable(wdev->fck);

 	omap_wdt_disable(wdev);
 	omap_wdt_adjust_timeout(timer_margin);

 	wdev->omap_wdt_miscdev.parent = &pdev->dev;
 	wdev->omap_wdt_miscdev.minor = WATCHDOG_MINOR;
 	wdev->omap_wdt_miscdev.name = "watchdog";
 	wdev->omap_wdt_miscdev.fops = &omap_wdt_fops;

 	ret = misc_register(&(wdev->omap_wdt_miscdev));
 	if (ret)
 		goto err_misc;

 	pr_info("OMAP Watchdog Timer Rev 0x%02x: initial timeout %d sec\n",
 		__raw_readl(wdev->base + OMAP_WATCHDOG_REV) & 0xFF,
 		timer_margin);

 	/* autogate OCP interface clock */
 	__raw_writel(0x01, wdev->base + OMAP_WATCHDOG_SYS_CONFIG);

 	clk_disable(wdev->ick);
 	clk_disable(wdev->fck);

 	omap_wdt_dev = pdev;

 	return 0;

 err_misc:
 	platform_set_drvdata(pdev, NULL);
 	iounmap(wdev->base);

 err_ioremap:
 	wdev->base = NULL;

 err_clk:
 	if (wdev->ick)
 		clk_put(wdev->ick);
 	if (wdev->fck)
 		clk_put(wdev->fck);
 	kfree(wdev);

 err_kzalloc:
 	release_mem_region(res->start, resource_size(res));

 err_busy:
 err_get_resource:

 	return ret;
 }

 static void omap_wdt_shutdown(struct platform_device *pdev)
 {
 	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

 	if (wdev->omap_wdt_users)
 		omap_wdt_disable(wdev);
 }

 static int __devexit omap_wdt_remove(struct platform_device *pdev)
 {
 	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);
 	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

 	if (!res)
 		return -ENOENT;

 	misc_deregister(&(wdev->omap_wdt_miscdev));
 	release_mem_region(res->start, resource_size(res));
 	platform_set_drvdata(pdev, NULL);

 	clk_put(wdev->ick);
 	clk_put(wdev->fck);
 	iounmap(wdev->base);

 	kfree(wdev);
 	omap_wdt_dev = NULL;

 	return 0;
 }

 #ifdef	CONFIG_PM

 /* REVISIT ... not clear this is the best way to handle system suspend; and
  * it's very inappropriate for selective device suspend (e.g. suspending this
  * through sysfs rather than by stopping the watchdog daemon).  Also, this
  * may not play well enough with NOWAYOUT...
  */

 static int omap_wdt_suspend(struct platform_device *pdev, pm_message_t state)
 {
 	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

 	if (wdev->omap_wdt_users)
 		omap_wdt_disable(wdev);

 	return 0;
 }

 static int omap_wdt_resume(struct platform_device *pdev)
 {
 	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

 	if (wdev->omap_wdt_users) {
 		omap_wdt_enable(wdev);
 		omap_wdt_ping(wdev);
 	}

 	return 0;
 }

 #else
 #define	omap_wdt_suspend	NULL
 #define	omap_wdt_resume		NULL
 #endif

 static struct platform_driver omap_wdt_driver = {
 	.probe		= omap_wdt_probe,
 	.remove		= __devexit_p(omap_wdt_remove),
 	.shutdown	= omap_wdt_shutdown,
 	.suspend	= omap_wdt_suspend,
 	.resume		= omap_wdt_resume,
 	.driver		= {
 		.owner	= THIS_MODULE,
 		.name	= "omap_wdt",
 	},
 };

 static int __init omap_wdt_init(void)
 {
 	spin_lock_init(&wdt_lock);
 	return platform_driver_register(&omap_wdt_driver);
 }

 static void __exit omap_wdt_exit(void)
 {
 	platform_driver_unregister(&omap_wdt_driver);
 }

 module_init(omap_wdt_init);
 module_exit(omap_wdt_exit);

 MODULE_AUTHOR("George G. Davis");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 MODULE_ALIAS("platform:omap_wdt");
	/*
	* omap_wdt.c
	*
	* Watchdog driver for the TI OMAP 16xx & 24xx/34xx 32KHz (non-secure) watchdog
	*
	* Author: MontaVista Software, Inc.
	* <gdavis@mvista.com> or <source@mvista.com>
	*
	* 2003 (c) MontaVista Software, Inc. 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.
	*
	* History:
	*
	* 20030527: George G. Davis <gdavis@mvista.com>
	* Initially based on linux-2.4.19-rmk7-pxa1/drivers/char/sa1100_wdt.c
	* (c) Copyright 2000 Oleg Drokin <green@crimea.edu>
	* Based on SoftDog driver by Alan Cox <alan@lxorguk.ukuu.org.uk>
	*
	* Copyright (c) 2004 Texas Instruments.
	* 1. Modified to support OMAP1610 32-KHz watchdog timer
	* 2. Ported to 2.6 kernel
	*
	* Copyright (c) 2005 David Brownell
	* Use the driver model and standard identifiers; handle bigger timeouts.
	*/

	#include <linux/module.h>
	#include <linux/types.h>
	#include <linux/kernel.h>
	#include <linux/fs.h>
	#include <linux/mm.h>
	#include <linux/miscdevice.h>
	#include <linux/watchdog.h>
	#include <linux/reboot.h>
	#include <linux/init.h>
	#include <linux/err.h>
	#include <linux/platform_device.h>
	#include <linux/moduleparam.h>
	#include <linux/clk.h>
	#include <linux/bitops.h>
	#include <linux/io.h>
	#include <linux/uaccess.h>
	#include <linux/slab.h>
	#include <mach/hardware.h>
	#include <plat/prcm.h>

	#include "omap_wdt.h"

	static struct platform_device *omap_wdt_dev;

	static unsigned timer_margin;
	module_param(timer_margin, uint, 0);
	MODULE_PARM_DESC(timer_margin, "initial watchdog timeout (in seconds)");

	static unsigned int wdt_trgr_pattern = 0x1234;
	static spinlock_t wdt_lock;

	struct omap_wdt_dev {
	void __iomem base; / physical */
	struct device *dev;
	int omap_wdt_users;
	struct clk *ick;
	struct clk *fck;
	struct resource *mem;
	struct miscdevice omap_wdt_miscdev;
	};

	static void omap_wdt_ping(struct omap_wdt_dev *wdev)
	{
	void __iomem *base = wdev->base;

	/* wait for posted write to complete */
	while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x08)
	cpu_relax();

	wdt_trgr_pattern = ~wdt_trgr_pattern;
	__raw_writel(wdt_trgr_pattern, (base + OMAP_WATCHDOG_TGR));

	/* wait for posted write to complete */
	while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x08)
	cpu_relax();
	/* reloaded WCRR from WLDR */
	}

	static void omap_wdt_enable(struct omap_wdt_dev *wdev)
	{
	void __iomem *base = wdev->base;

	/* Sequence to enable the watchdog */
	__raw_writel(0xBBBB, base + OMAP_WATCHDOG_SPR);
	while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x10)
	cpu_relax();

	__raw_writel(0x4444, base + OMAP_WATCHDOG_SPR);
	while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x10)
	cpu_relax();
	}

	static void omap_wdt_disable(struct omap_wdt_dev *wdev)
	{
	void __iomem *base = wdev->base;

	/* sequence required to disable watchdog */
	__raw_writel(0xAAAA, base + OMAP_WATCHDOG_SPR); /* TIMER_MODE */
	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x10)
	cpu_relax();

	__raw_writel(0x5555, base + OMAP_WATCHDOG_SPR); /* TIMER_MODE */
	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x10)
	cpu_relax();
	}

	static void omap_wdt_adjust_timeout(unsigned new_timeout)
	{
	if (new_timeout < TIMER_MARGIN_MIN)
	new_timeout = TIMER_MARGIN_DEFAULT;
	if (new_timeout > TIMER_MARGIN_MAX)
	new_timeout = TIMER_MARGIN_MAX;
	timer_margin = new_timeout;
	}

	static void omap_wdt_set_timeout(struct omap_wdt_dev *wdev)
	{
	u32 pre_margin = GET_WLDR_VAL(timer_margin);
	void __iomem *base = wdev->base;

	/* just count up at 32 KHz */
	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x04)
	cpu_relax();

	__raw_writel(pre_margin, base + OMAP_WATCHDOG_LDR);
	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x04)
	cpu_relax();
	}

	/*
	* Allow only one task to hold it open
	*/
	static int omap_wdt_open(struct inode inode, struct file file)
	{
	struct omap_wdt_dev *wdev = platform_get_drvdata(omap_wdt_dev);
	void __iomem *base = wdev->base;

	if (test_and_set_bit(1, (unsigned long *)&(wdev->omap_wdt_users)))
	return -EBUSY;

	clk_enable(wdev->ick); /* Enable the interface clock */
	clk_enable(wdev->fck); /* Enable the functional clock */

	/* initialize prescaler */
	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x01)
	cpu_relax();

	__raw_writel((1 << 5) \| (PTV << 2), base + OMAP_WATCHDOG_CNTRL);
	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x01)
	cpu_relax();

	file->private_data = (void *) wdev;

	omap_wdt_set_timeout(wdev);
	omap_wdt_ping(wdev); /* trigger loading of new timeout value */
	omap_wdt_enable(wdev);

	return nonseekable_open(inode, file);
	}

	static int omap_wdt_release(struct inode inode, struct file file)
	{
	struct omap_wdt_dev *wdev = file->private_data;

	/*
	* Shut off the timer unless NOWAYOUT is defined.
	*/
	#ifndef CONFIG_WATCHDOG_NOWAYOUT

	omap_wdt_disable(wdev);

	clk_disable(wdev->ick);
	clk_disable(wdev->fck);
	#else
	printk(KERN_CRIT "omap_wdt: Unexpected close, not stopping!\n");
	#endif
	wdev->omap_wdt_users = 0;

	return 0;
	}

	static ssize_t omap_wdt_write(struct file file, const char __user data,
	size_t len, loff_t *ppos)
	{
	struct omap_wdt_dev *wdev = file->private_data;

	/* Refresh LOAD_TIME. */
	if (len) {
	spin_lock(&wdt_lock);
	omap_wdt_ping(wdev);
	spin_unlock(&wdt_lock);
	}
	return len;
	}

	static long omap_wdt_ioctl(struct file *file, unsigned int cmd,
	unsigned long arg)
	{
	struct omap_wdt_dev *wdev;
	int new_margin;
	static const struct watchdog_info ident = {
	.identity = "OMAP Watchdog",
	.options = WDIOF_SETTIMEOUT,
	.firmware_version = 0,
	};

	wdev = file->private_data;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
	return copy_to_user((struct watchdog_info __user *)arg, &ident,
	sizeof(ident));
	case WDIOC_GETSTATUS:
	return put_user(0, (int __user *)arg);
	case WDIOC_GETBOOTSTATUS:
	if (cpu_is_omap16xx())
	return put_user(__raw_readw(ARM_SYSST),
	(int __user *)arg);
	if (cpu_is_omap24xx())
	return put_user(omap_prcm_get_reset_sources(),
	(int __user *)arg);
	case WDIOC_KEEPALIVE:
	spin_lock(&wdt_lock);
	omap_wdt_ping(wdev);
	spin_unlock(&wdt_lock);
	return 0;
	case WDIOC_SETTIMEOUT:
	if (get_user(new_margin, (int __user *)arg))
	return -EFAULT;
	omap_wdt_adjust_timeout(new_margin);

	spin_lock(&wdt_lock);
	omap_wdt_disable(wdev);
	omap_wdt_set_timeout(wdev);
	omap_wdt_enable(wdev);

	omap_wdt_ping(wdev);
	spin_unlock(&wdt_lock);
	/* Fall */
	case WDIOC_GETTIMEOUT:
	return put_user(timer_margin, (int __user *)arg);
	default:
	return -ENOTTY;
	}
	}

	static const struct file_operations omap_wdt_fops = {
	.owner = THIS_MODULE,
	.write = omap_wdt_write,
	.unlocked_ioctl = omap_wdt_ioctl,
	.open = omap_wdt_open,
	.release = omap_wdt_release,
	.llseek = no_llseek,
	};

	static int __devinit omap_wdt_probe(struct platform_device *pdev)
	{
	struct resource res, mem;
	struct omap_wdt_dev *wdev;
	int ret;

	/* reserve static register mappings */
	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res) {
	ret = -ENOENT;
	goto err_get_resource;
	}

	if (omap_wdt_dev) {
	ret = -EBUSY;
	goto err_busy;
	}

	mem = request_mem_region(res->start, resource_size(res), pdev->name);
	if (!mem) {
	ret = -EBUSY;
	goto err_busy;
	}

	wdev = kzalloc(sizeof(struct omap_wdt_dev), GFP_KERNEL);
	if (!wdev) {
	ret = -ENOMEM;
	goto err_kzalloc;
	}

	wdev->omap_wdt_users = 0;
	wdev->mem = mem;

	wdev->ick = clk_get(&pdev->dev, "ick");
	if (IS_ERR(wdev->ick)) {
	ret = PTR_ERR(wdev->ick);
	wdev->ick = NULL;
	goto err_clk;
	}
	wdev->fck = clk_get(&pdev->dev, "fck");
	if (IS_ERR(wdev->fck)) {
	ret = PTR_ERR(wdev->fck);
	wdev->fck = NULL;
	goto err_clk;
	}

	wdev->base = ioremap(res->start, resource_size(res));
	if (!wdev->base) {
	ret = -ENOMEM;
	goto err_ioremap;
	}

	platform_set_drvdata(pdev, wdev);

	clk_enable(wdev->ick);
	clk_enable(wdev->fck);

	omap_wdt_disable(wdev);
	omap_wdt_adjust_timeout(timer_margin);

	wdev->omap_wdt_miscdev.parent = &pdev->dev;
	wdev->omap_wdt_miscdev.minor = WATCHDOG_MINOR;
	wdev->omap_wdt_miscdev.name = "watchdog";
	wdev->omap_wdt_miscdev.fops = &omap_wdt_fops;

	ret = misc_register(&(wdev->omap_wdt_miscdev));
	if (ret)
	goto err_misc;

	pr_info("OMAP Watchdog Timer Rev 0x%02x: initial timeout %d sec\n",
	__raw_readl(wdev->base + OMAP_WATCHDOG_REV) & 0xFF,
	timer_margin);

	/* autogate OCP interface clock */
	__raw_writel(0x01, wdev->base + OMAP_WATCHDOG_SYS_CONFIG);

	clk_disable(wdev->ick);
	clk_disable(wdev->fck);

	omap_wdt_dev = pdev;

	return 0;

	err_misc:
	platform_set_drvdata(pdev, NULL);
	iounmap(wdev->base);

	err_ioremap:
	wdev->base = NULL;

	err_clk:
	if (wdev->ick)
	clk_put(wdev->ick);
	if (wdev->fck)
	clk_put(wdev->fck);
	kfree(wdev);

	err_kzalloc:
	release_mem_region(res->start, resource_size(res));

	err_busy:
	err_get_resource:

	return ret;
	}

	static void omap_wdt_shutdown(struct platform_device *pdev)
	{
	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

	if (wdev->omap_wdt_users)
	omap_wdt_disable(wdev);
	}

	static int __devexit omap_wdt_remove(struct platform_device *pdev)
	{
	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);
	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	if (!res)
	return -ENOENT;

	misc_deregister(&(wdev->omap_wdt_miscdev));
	release_mem_region(res->start, resource_size(res));
	platform_set_drvdata(pdev, NULL);

	clk_put(wdev->ick);
	clk_put(wdev->fck);
	iounmap(wdev->base);

	kfree(wdev);
	omap_wdt_dev = NULL;

	return 0;
	}

	#ifdef CONFIG_PM

	/* REVISIT ... not clear this is the best way to handle system suspend; and
	* it's very inappropriate for selective device suspend (e.g. suspending this
	* through sysfs rather than by stopping the watchdog daemon). Also, this
	* may not play well enough with NOWAYOUT...
	*/

	static int omap_wdt_suspend(struct platform_device *pdev, pm_message_t state)
	{
	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

	if (wdev->omap_wdt_users)
	omap_wdt_disable(wdev);

	return 0;
	}

	static int omap_wdt_resume(struct platform_device *pdev)
	{
	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

	if (wdev->omap_wdt_users) {
	omap_wdt_enable(wdev);
	omap_wdt_ping(wdev);
	}

	return 0;
	}

	#else
	#define omap_wdt_suspend NULL
	#define omap_wdt_resume NULL
	#endif

	static struct platform_driver omap_wdt_driver = {
	.probe = omap_wdt_probe,
	.remove = __devexit_p(omap_wdt_remove),
	.shutdown = omap_wdt_shutdown,
	.suspend = omap_wdt_suspend,
	.resume = omap_wdt_resume,
	.driver = {
	.owner = THIS_MODULE,
	.name = "omap_wdt",
	},
	};

	static int __init omap_wdt_init(void)
	{
	spin_lock_init(&wdt_lock);
	return platform_driver_register(&omap_wdt_driver);
	}

	static void __exit omap_wdt_exit(void)
	{
	platform_driver_unregister(&omap_wdt_driver);
	}

	module_init(omap_wdt_init);
	module_exit(omap_wdt_exit);

	MODULE_AUTHOR("George G. Davis");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
	MODULE_ALIAS("platform:omap_wdt");