drivers/watchdog/xen_wdt.c - kernel/common - Git at Google

 /*
  *	Xen Watchdog Driver
  *
  *	(c) Copyright 2010 Novell, Inc.
  *
  *	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.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #define DRV_NAME	"wdt"
 #define DRV_VERSION	"0.01"

 #include <linux/bug.h>
 #include <linux/errno.h>
 #include <linux/fs.h>
 #include <linux/hrtimer.h>
 #include <linux/kernel.h>
 #include <linux/ktime.h>
 #include <linux/init.h>
 #include <linux/miscdevice.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/platform_device.h>
 #include <linux/spinlock.h>
 #include <linux/uaccess.h>
 #include <linux/watchdog.h>
 #include <xen/xen.h>
 #include <asm/xen/hypercall.h>
 #include <xen/interface/sched.h>

 static struct platform_device *platform_device;
 static DEFINE_SPINLOCK(wdt_lock);
 static struct sched_watchdog wdt;
 static __kernel_time_t wdt_expires;
 static bool is_active, expect_release;

 #define WATCHDOG_TIMEOUT 60 /* in seconds */
 static unsigned int timeout = WATCHDOG_TIMEOUT;
 module_param(timeout, uint, S_IRUGO);
 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
 	"(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");

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

 static inline __kernel_time_t set_timeout(void)
 {
 	wdt.timeout = timeout;
 	return ktime_to_timespec(ktime_get()).tv_sec + timeout;
 }

 static int xen_wdt_start(void)
 {
 	__kernel_time_t expires;
 	int err;

 	spin_lock(&wdt_lock);

 	expires = set_timeout();
 	if (!wdt.id)
 		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
 	else
 		err = -EBUSY;
 	if (err > 0) {
 		wdt.id = err;
 		wdt_expires = expires;
 		err = 0;
 	} else
 		BUG_ON(!err);

 	spin_unlock(&wdt_lock);

 	return err;
 }

 static int xen_wdt_stop(void)
 {
 	int err = 0;

 	spin_lock(&wdt_lock);

 	wdt.timeout = 0;
 	if (wdt.id)
 		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
 	if (!err)
 		wdt.id = 0;

 	spin_unlock(&wdt_lock);

 	return err;
 }

 static int xen_wdt_kick(void)
 {
 	__kernel_time_t expires;
 	int err;

 	spin_lock(&wdt_lock);

 	expires = set_timeout();
 	if (wdt.id)
 		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
 	else
 		err = -ENXIO;
 	if (!err)
 		wdt_expires = expires;

 	spin_unlock(&wdt_lock);

 	return err;
 }

 static int xen_wdt_open(struct inode *inode, struct file *file)
 {
 	int err;

 	/* /dev/watchdog can only be opened once */
 	if (xchg(&is_active, true))
 		return -EBUSY;

 	err = xen_wdt_start();
 	if (err == -EBUSY)
 		err = xen_wdt_kick();
 	return err ?: nonseekable_open(inode, file);
 }

 static int xen_wdt_release(struct inode *inode, struct file *file)
 {
 	int err = 0;

 	if (expect_release)
 		err = xen_wdt_stop();
 	else {
 		pr_crit("unexpected close, not stopping watchdog!\n");
 		xen_wdt_kick();
 	}
 	is_active = err;
 	expect_release = false;
 	return err;
 }

 static ssize_t xen_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;

 			/* in case it was set long ago */
 			expect_release = false;

 			/* 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 = true;
 			}
 		}

 		/* someone wrote to us, we should reload the timer */
 		xen_wdt_kick();
 	}
 	return len;
 }

 static long xen_wdt_ioctl(struct file *file, unsigned int cmd,
 			  unsigned long arg)
 {
 	int new_options, retval = -EINVAL;
 	int new_timeout;
 	int __user *argp = (void __user *)arg;
 	static const struct watchdog_info ident = {
 		.options =		WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 		.firmware_version =	0,
 		.identity =		DRV_NAME,
 	};

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

 	case WDIOC_GETSTATUS:
 	case WDIOC_GETBOOTSTATUS:
 		return put_user(0, argp);

 	case WDIOC_SETOPTIONS:
 		if (get_user(new_options, argp))
 			return -EFAULT;

 		if (new_options & WDIOS_DISABLECARD)
 			retval = xen_wdt_stop();
 		if (new_options & WDIOS_ENABLECARD) {
 			retval = xen_wdt_start();
 			if (retval == -EBUSY)
 				retval = xen_wdt_kick();
 		}
 		return retval;

 	case WDIOC_KEEPALIVE:
 		xen_wdt_kick();
 		return 0;

 	case WDIOC_SETTIMEOUT:
 		if (get_user(new_timeout, argp))
 			return -EFAULT;
 		if (!new_timeout)
 			return -EINVAL;
 		timeout = new_timeout;
 		xen_wdt_kick();
 		/* fall through */
 	case WDIOC_GETTIMEOUT:
 		return put_user(timeout, argp);

 	case WDIOC_GETTIMELEFT:
 		retval = wdt_expires - ktime_to_timespec(ktime_get()).tv_sec;
 		return put_user(retval, argp);
 	}

 	return -ENOTTY;
 }

 static const struct file_operations xen_wdt_fops = {
 	.owner =		THIS_MODULE,
 	.llseek =		no_llseek,
 	.write =		xen_wdt_write,
 	.unlocked_ioctl =	xen_wdt_ioctl,
 	.open =			xen_wdt_open,
 	.release =		xen_wdt_release,
 };

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

 static int __devinit xen_wdt_probe(struct platform_device *dev)
 {
 	struct sched_watchdog wd = { .id = ~0 };
 	int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);

 	switch (ret) {
 	case -EINVAL:
 		if (!timeout) {
 			timeout = WATCHDOG_TIMEOUT;
 			pr_info("timeout value invalid, using %d\n", timeout);
 		}

 		ret = misc_register(&xen_wdt_miscdev);
 		if (ret) {
 			pr_err("cannot register miscdev on minor=%d (%d)\n",
 			       WATCHDOG_MINOR, ret);
 			break;
 		}

 		pr_info("initialized (timeout=%ds, nowayout=%d)\n",
 			timeout, nowayout);
 		break;

 	case -ENOSYS:
 		pr_info("not supported\n");
 		ret = -ENODEV;
 		break;

 	default:
 		pr_info("bogus return value %d\n", ret);
 		break;
 	}

 	return ret;
 }

 static int __devexit xen_wdt_remove(struct platform_device *dev)
 {
 	/* Stop the timer before we leave */
 	if (!nowayout)
 		xen_wdt_stop();

 	misc_deregister(&xen_wdt_miscdev);

 	return 0;
 }

 static void xen_wdt_shutdown(struct platform_device *dev)
 {
 	xen_wdt_stop();
 }

 static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
 {
 	typeof(wdt.id) id = wdt.id;
 	int rc = xen_wdt_stop();

 	wdt.id = id;
 	return rc;
 }

 static int xen_wdt_resume(struct platform_device *dev)
 {
 	if (!wdt.id)
 		return 0;
 	wdt.id = 0;
 	return xen_wdt_start();
 }

 static struct platform_driver xen_wdt_driver = {
 	.probe          = xen_wdt_probe,
 	.remove         = __devexit_p(xen_wdt_remove),
 	.shutdown       = xen_wdt_shutdown,
 	.suspend        = xen_wdt_suspend,
 	.resume         = xen_wdt_resume,
 	.driver         = {
 		.owner  = THIS_MODULE,
 		.name   = DRV_NAME,
 	},
 };

 static int __init xen_wdt_init_module(void)
 {
 	int err;

 	if (!xen_domain())
 		return -ENODEV;

 	pr_info("Xen WatchDog Timer Driver v%s\n", DRV_VERSION);

 	err = platform_driver_register(&xen_wdt_driver);
 	if (err)
 		return err;

 	platform_device = platform_device_register_simple(DRV_NAME,
 								  -1, NULL, 0);
 	if (IS_ERR(platform_device)) {
 		err = PTR_ERR(platform_device);
 		platform_driver_unregister(&xen_wdt_driver);
 	}

 	return err;
 }

 static void __exit xen_wdt_cleanup_module(void)
 {
 	platform_device_unregister(platform_device);
 	platform_driver_unregister(&xen_wdt_driver);
 	pr_info("module unloaded\n");
 }

 module_init(xen_wdt_init_module);
 module_exit(xen_wdt_cleanup_module);

 MODULE_AUTHOR("Jan Beulich <[email protected]>");
 MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
 MODULE_VERSION(DRV_VERSION);
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
	/*
	* Xen Watchdog Driver
	*
	* (c) Copyright 2010 Novell, Inc.
	*
	* 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.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#define DRV_NAME "wdt"
	#define DRV_VERSION "0.01"

	#include <linux/bug.h>
	#include <linux/errno.h>
	#include <linux/fs.h>
	#include <linux/hrtimer.h>
	#include <linux/kernel.h>
	#include <linux/ktime.h>
	#include <linux/init.h>
	#include <linux/miscdevice.h>
	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/platform_device.h>
	#include <linux/spinlock.h>
	#include <linux/uaccess.h>
	#include <linux/watchdog.h>
	#include <xen/xen.h>
	#include <asm/xen/hypercall.h>
	#include <xen/interface/sched.h>

	static struct platform_device *platform_device;
	static DEFINE_SPINLOCK(wdt_lock);
	static struct sched_watchdog wdt;
	static __kernel_time_t wdt_expires;
	static bool is_active, expect_release;

	#define WATCHDOG_TIMEOUT 60 /* in seconds */
	static unsigned int timeout = WATCHDOG_TIMEOUT;
	module_param(timeout, uint, S_IRUGO);
	MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
	"(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");

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

	static inline __kernel_time_t set_timeout(void)
	{
	wdt.timeout = timeout;
	return ktime_to_timespec(ktime_get()).tv_sec + timeout;
	}

	static int xen_wdt_start(void)
	{
	__kernel_time_t expires;
	int err;

	spin_lock(&wdt_lock);

	expires = set_timeout();
	if (!wdt.id)
	err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
	else
	err = -EBUSY;
	if (err > 0) {
	wdt.id = err;
	wdt_expires = expires;
	err = 0;
	} else
	BUG_ON(!err);

	spin_unlock(&wdt_lock);

	return err;
	}

	static int xen_wdt_stop(void)
	{
	int err = 0;

	spin_lock(&wdt_lock);

	wdt.timeout = 0;
	if (wdt.id)
	err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
	if (!err)
	wdt.id = 0;

	spin_unlock(&wdt_lock);

	return err;
	}

	static int xen_wdt_kick(void)
	{
	__kernel_time_t expires;
	int err;

	spin_lock(&wdt_lock);

	expires = set_timeout();
	if (wdt.id)
	err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
	else
	err = -ENXIO;
	if (!err)
	wdt_expires = expires;

	spin_unlock(&wdt_lock);

	return err;
	}

	static int xen_wdt_open(struct inode inode, struct file file)
	{
	int err;

	/* /dev/watchdog can only be opened once */
	if (xchg(&is_active, true))
	return -EBUSY;

	err = xen_wdt_start();
	if (err == -EBUSY)
	err = xen_wdt_kick();
	return err ?: nonseekable_open(inode, file);
	}

	static int xen_wdt_release(struct inode inode, struct file file)
	{
	int err = 0;

	if (expect_release)
	err = xen_wdt_stop();
	else {
	pr_crit("unexpected close, not stopping watchdog!\n");
	xen_wdt_kick();
	}
	is_active = err;
	expect_release = false;
	return err;
	}

	static ssize_t xen_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;

	/* in case it was set long ago */
	expect_release = false;

	/* 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 = true;
	}
	}

	/* someone wrote to us, we should reload the timer */
	xen_wdt_kick();
	}
	return len;
	}

	static long xen_wdt_ioctl(struct file *file, unsigned int cmd,
	unsigned long arg)
	{
	int new_options, retval = -EINVAL;
	int new_timeout;
	int __user argp = (void __user )arg;
	static const struct watchdog_info ident = {
	.options = WDIOF_SETTIMEOUT \| WDIOF_MAGICCLOSE,
	.firmware_version = 0,
	.identity = DRV_NAME,
	};

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

	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
	return put_user(0, argp);

	case WDIOC_SETOPTIONS:
	if (get_user(new_options, argp))
	return -EFAULT;

	if (new_options & WDIOS_DISABLECARD)
	retval = xen_wdt_stop();
	if (new_options & WDIOS_ENABLECARD) {
	retval = xen_wdt_start();
	if (retval == -EBUSY)
	retval = xen_wdt_kick();
	}
	return retval;

	case WDIOC_KEEPALIVE:
	xen_wdt_kick();
	return 0;

	case WDIOC_SETTIMEOUT:
	if (get_user(new_timeout, argp))
	return -EFAULT;
	if (!new_timeout)
	return -EINVAL;
	timeout = new_timeout;
	xen_wdt_kick();
	/* fall through */
	case WDIOC_GETTIMEOUT:
	return put_user(timeout, argp);

	case WDIOC_GETTIMELEFT:
	retval = wdt_expires - ktime_to_timespec(ktime_get()).tv_sec;
	return put_user(retval, argp);
	}

	return -ENOTTY;
	}

	static const struct file_operations xen_wdt_fops = {
	.owner = THIS_MODULE,
	.llseek = no_llseek,
	.write = xen_wdt_write,
	.unlocked_ioctl = xen_wdt_ioctl,
	.open = xen_wdt_open,
	.release = xen_wdt_release,
	};

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

	static int __devinit xen_wdt_probe(struct platform_device *dev)
	{
	struct sched_watchdog wd = { .id = ~0 };
	int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);

	switch (ret) {
	case -EINVAL:
	if (!timeout) {
	timeout = WATCHDOG_TIMEOUT;
	pr_info("timeout value invalid, using %d\n", timeout);
	}

	ret = misc_register(&xen_wdt_miscdev);
	if (ret) {
	pr_err("cannot register miscdev on minor=%d (%d)\n",
	WATCHDOG_MINOR, ret);
	break;
	}

	pr_info("initialized (timeout=%ds, nowayout=%d)\n",
	timeout, nowayout);
	break;

	case -ENOSYS:
	pr_info("not supported\n");
	ret = -ENODEV;
	break;

	default:
	pr_info("bogus return value %d\n", ret);
	break;
	}

	return ret;
	}

	static int __devexit xen_wdt_remove(struct platform_device *dev)
	{
	/* Stop the timer before we leave */
	if (!nowayout)
	xen_wdt_stop();

	misc_deregister(&xen_wdt_miscdev);

	return 0;
	}

	static void xen_wdt_shutdown(struct platform_device *dev)
	{
	xen_wdt_stop();
	}

	static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
	{
	typeof(wdt.id) id = wdt.id;
	int rc = xen_wdt_stop();

	wdt.id = id;
	return rc;
	}

	static int xen_wdt_resume(struct platform_device *dev)
	{
	if (!wdt.id)
	return 0;
	wdt.id = 0;
	return xen_wdt_start();
	}

	static struct platform_driver xen_wdt_driver = {
	.probe = xen_wdt_probe,
	.remove = __devexit_p(xen_wdt_remove),
	.shutdown = xen_wdt_shutdown,
	.suspend = xen_wdt_suspend,
	.resume = xen_wdt_resume,
	.driver = {
	.owner = THIS_MODULE,
	.name = DRV_NAME,
	},
	};

	static int __init xen_wdt_init_module(void)
	{
	int err;

	if (!xen_domain())
	return -ENODEV;

	pr_info("Xen WatchDog Timer Driver v%s\n", DRV_VERSION);

	err = platform_driver_register(&xen_wdt_driver);
	if (err)
	return err;

	platform_device = platform_device_register_simple(DRV_NAME,
	-1, NULL, 0);
	if (IS_ERR(platform_device)) {
	err = PTR_ERR(platform_device);
	platform_driver_unregister(&xen_wdt_driver);
	}

	return err;
	}

	static void __exit xen_wdt_cleanup_module(void)
	{
	platform_device_unregister(platform_device);
	platform_driver_unregister(&xen_wdt_driver);
	pr_info("module unloaded\n");
	}

	module_init(xen_wdt_init_module);
	module_exit(xen_wdt_cleanup_module);

	MODULE_AUTHOR("Jan Beulich <[email protected]>");
	MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
	MODULE_VERSION(DRV_VERSION);
	MODULE_LICENSE("GPL");
	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);