[mirror_ubuntu-bionic-kernel.git] / drivers / watchdog / xen_wdt.c

/*
 *	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)
{
	if (expect_release)
		xen_wdt_stop();
	else {
		pr_crit("unexpected close, not stopping watchdog!\n");
		xen_wdt_kick();
	}
	is_active = false;
	expect_release = false;
	return 0;
}

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)
{
	return xen_wdt_stop();
}

static int xen_wdt_resume(struct platform_device *dev)
{
	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 <jbeulich@novell.com>");
MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
MODULE_VERSION(DRV_VERSION);
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
Commit	Line	Data
066d6c7f JB	1	/*
	2	* Xen Watchdog Driver
	3	*
	4	* (c) Copyright 2010 Novell, Inc.
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*/
	11
27c766aa JP	12	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
27c766aa JP	13
066d6c7f JB	14	#define DRV_NAME "wdt"
066d6c7f JB	15	#define DRV_VERSION "0.01"
066d6c7f JB	16
	17	#include <linux/bug.h>
	18	#include <linux/errno.h>
	19	#include <linux/fs.h>
	20	#include <linux/hrtimer.h>
	21	#include <linux/kernel.h>
	22	#include <linux/ktime.h>
	23	#include <linux/init.h>
	24	#include <linux/miscdevice.h>
	25	#include <linux/module.h>
	26	#include <linux/moduleparam.h>
	27	#include <linux/platform_device.h>
	28	#include <linux/spinlock.h>
	29	#include <linux/uaccess.h>
	30	#include <linux/watchdog.h>
	31	#include <xen/xen.h>
	32	#include <asm/xen/hypercall.h>
	33	#include <xen/interface/sched.h>
	34
	35	static struct platform_device *platform_device;
	36	static DEFINE_SPINLOCK(wdt_lock);
	37	static struct sched_watchdog wdt;
	38	static __kernel_time_t wdt_expires;
	39	static bool is_active, expect_release;
	40
	41	#define WATCHDOG_TIMEOUT 60 /* in seconds */
	42	static unsigned int timeout = WATCHDOG_TIMEOUT;
	43	module_param(timeout, uint, S_IRUGO);
	44	MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
	45	"(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
	46
	47	static bool nowayout = WATCHDOG_NOWAYOUT;
	48	module_param(nowayout, bool, S_IRUGO);
	49	MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
	50	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
	51
	52	static inline __kernel_time_t set_timeout(void)
	53	{
	54	wdt.timeout = timeout;
	55	return ktime_to_timespec(ktime_get()).tv_sec + timeout;
	56	}
	57
	58	static int xen_wdt_start(void)
	59	{
	60	__kernel_time_t expires;
	61	int err;
	62
	63	spin_lock(&wdt_lock);
	64
	65	expires = set_timeout();
	66	if (!wdt.id)
	67	err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
	68	else
	69	err = -EBUSY;
	70	if (err > 0) {
	71	wdt.id = err;
	72	wdt_expires = expires;
	73	err = 0;
	74	} else
	75	BUG_ON(!err);
	76
	77	spin_unlock(&wdt_lock);
	78
	79	return err;
80	}
81
82	static int xen_wdt_stop(void)
83	{
84	int err = 0;
85
86	spin_lock(&wdt_lock);
87
88	wdt.timeout = 0;
89	if (wdt.id)
90	err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
91	if (!err)
92	wdt.id = 0;
93
94	spin_unlock(&wdt_lock);
95
96	return err;
97	}
98
99	static int xen_wdt_kick(void)
100	{
101	__kernel_time_t expires;
102	int err;
103
104	spin_lock(&wdt_lock);
105
106	expires = set_timeout();
107	if (wdt.id)
108	err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
109	else
110	err = -ENXIO;
111	if (!err)
112	wdt_expires = expires;
113
114	spin_unlock(&wdt_lock);
115
116	return err;
117	}
118
119	static int xen_wdt_open(struct inode inode, struct file file)
120	{
121	int err;
122
123	/* /dev/watchdog can only be opened once */
124	if (xchg(&is_active, true))
125	return -EBUSY;
126
127	err = xen_wdt_start();
128	if (err == -EBUSY)
129	err = xen_wdt_kick();
130	return err ?: nonseekable_open(inode, file);
131	}
132
133	static int xen_wdt_release(struct inode inode, struct file file)
134	{
135	if (expect_release)
136	xen_wdt_stop();
137	else {
27c766aa	138	pr_crit("unexpected close, not stopping watchdog!\n");
066d6c7f JB	139	xen_wdt_kick();
	140	}
	141	is_active = false;
	142	expect_release = false;
	143	return 0;
	144	}
	145
	146	static ssize_t xen_wdt_write(struct file file, const char __user data,
	147	size_t len, loff_t *ppos)
	148	{
	149	/* See if we got the magic character 'V' and reload the timer */
	150	if (len) {
	151	if (!nowayout) {
	152	size_t i;
	153
	154	/* in case it was set long ago */
	155	expect_release = false;
	156
	157	/* scan to see whether or not we got the magic
	158	character */
	159	for (i = 0; i != len; i++) {
	160	char c;
	161	if (get_user(c, data + i))
	162	return -EFAULT;
	163	if (c == 'V')
	164	expect_release = true;
	165	}
	166	}
	167
	168	/* someone wrote to us, we should reload the timer */
	169	xen_wdt_kick();
	170	}
	171	return len;
	172	}
	173
	174	static long xen_wdt_ioctl(struct file *file, unsigned int cmd,
	175	unsigned long arg)
	176	{
	177	int new_options, retval = -EINVAL;
	178	int new_timeout;
	179	int __user argp = (void __user )arg;
	180	static const struct watchdog_info ident = {
	181	.options = WDIOF_SETTIMEOUT \| WDIOF_MAGICCLOSE,
	182	.firmware_version = 0,
	183	.identity = DRV_NAME,
	184	};
	185
	186	switch (cmd) {
	187	case WDIOC_GETSUPPORT:
	188	return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
	189
	190	case WDIOC_GETSTATUS:
	191	case WDIOC_GETBOOTSTATUS:
	192	return put_user(0, argp);
	193
	194	case WDIOC_SETOPTIONS:
	195	if (get_user(new_options, argp))
	196	return -EFAULT;
	197
	198	if (new_options & WDIOS_DISABLECARD)
	199	retval = xen_wdt_stop();
	200	if (new_options & WDIOS_ENABLECARD) {
	201	retval = xen_wdt_start();
	202	if (retval == -EBUSY)
203	retval = xen_wdt_kick();
204	}
205	return retval;
206
207	case WDIOC_KEEPALIVE:
208	xen_wdt_kick();
209	return 0;
210
211	case WDIOC_SETTIMEOUT:
212	if (get_user(new_timeout, argp))
213	return -EFAULT;
214	if (!new_timeout)
215	return -EINVAL;
216	timeout = new_timeout;
217	xen_wdt_kick();
218	/* fall through */
219	case WDIOC_GETTIMEOUT:
220	return put_user(timeout, argp);
221
222	case WDIOC_GETTIMELEFT:
223	retval = wdt_expires - ktime_to_timespec(ktime_get()).tv_sec;
224	return put_user(retval, argp);
225	}
226
227	return -ENOTTY;
228	}
229
230	static const struct file_operations xen_wdt_fops = {
231	.owner = THIS_MODULE,
232	.llseek = no_llseek,
233	.write = xen_wdt_write,
234	.unlocked_ioctl = xen_wdt_ioctl,
235	.open = xen_wdt_open,
236	.release = xen_wdt_release,
237	};
238
239	static struct miscdevice xen_wdt_miscdev = {
240	.minor = WATCHDOG_MINOR,
241	.name = "watchdog",
242	.fops = &xen_wdt_fops,
243	};
244
245	static int __devinit xen_wdt_probe(struct platform_device *dev)
246	{
247	struct sched_watchdog wd = { .id = ~0 };
248	int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
249
250	switch (ret) {
251	case -EINVAL:
252	if (!timeout) {
253	timeout = WATCHDOG_TIMEOUT;
27c766aa	254	pr_info("timeout value invalid, using %d\n", timeout);
066d6c7f JB	255	}
	256
	257	ret = misc_register(&xen_wdt_miscdev);
	258	if (ret) {
27c766aa	259	pr_err("cannot register miscdev on minor=%d (%d)\n",
066d6c7f JB	260	WATCHDOG_MINOR, ret);
	261	break;
	262	}
	263
27c766aa JP	264	pr_info("initialized (timeout=%ds, nowayout=%d)\n",
27c766aa JP	265	timeout, nowayout);
066d6c7f JB	266	break;
	267
	268	case -ENOSYS:
27c766aa	269	pr_info("not supported\n");
066d6c7f JB	270	ret = -ENODEV;
	271	break;
	272
	273	default:
27c766aa	274	pr_info("bogus return value %d\n", ret);
066d6c7f JB	275	break;
	276	}
	277
	278	return ret;
	279	}
	280
	281	static int __devexit xen_wdt_remove(struct platform_device *dev)
	282	{
	283	/* Stop the timer before we leave */
	284	if (!nowayout)
	285	xen_wdt_stop();
	286
	287	misc_deregister(&xen_wdt_miscdev);
	288
	289	return 0;
	290	}
	291
	292	static void xen_wdt_shutdown(struct platform_device *dev)
	293	{
	294	xen_wdt_stop();
	295	}
	296
	297	static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
	298	{
	299	return xen_wdt_stop();
	300	}
	301
	302	static int xen_wdt_resume(struct platform_device *dev)
	303	{
	304	return xen_wdt_start();
	305	}
	306
	307	static struct platform_driver xen_wdt_driver = {
	308	.probe = xen_wdt_probe,
	309	.remove = __devexit_p(xen_wdt_remove),
	310	.shutdown = xen_wdt_shutdown,
	311	.suspend = xen_wdt_suspend,
	312	.resume = xen_wdt_resume,
	313	.driver = {
	314	.owner = THIS_MODULE,
	315	.name = DRV_NAME,
	316	},
	317	};
	318
	319	static int __init xen_wdt_init_module(void)
	320	{
	321	int err;
	322
	323	if (!xen_domain())
	324	return -ENODEV;
	325
27c766aa	326	pr_info("Xen WatchDog Timer Driver v%s\n", DRV_VERSION);
066d6c7f JB	327
	328	err = platform_driver_register(&xen_wdt_driver);
	329	if (err)
	330	return err;
	331
	332	platform_device = platform_device_register_simple(DRV_NAME,
	333	-1, NULL, 0);
	334	if (IS_ERR(platform_device)) {
	335	err = PTR_ERR(platform_device);
	336	platform_driver_unregister(&xen_wdt_driver);
	337	}
	338
	339	return err;
	340	}
	341
	342	static void __exit xen_wdt_cleanup_module(void)
	343	{
	344	platform_device_unregister(platform_device);
	345	platform_driver_unregister(&xen_wdt_driver);
27c766aa	346	pr_info("module unloaded\n");
066d6c7f JB	347	}
	348
	349	module_init(xen_wdt_init_module);
	350	module_exit(xen_wdt_cleanup_module);
	351
	352	MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>");
	353	MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
	354	MODULE_VERSION(DRV_VERSION);
	355	MODULE_LICENSE("GPL");
	356	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);