[deliverable/linux.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 DRV_NAME	"wdt"
#define DRV_VERSION	"0.01"
#define PFX		DRV_NAME ": "

#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 {
		printk(KERN_CRIT PFX
		       "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;
			printk(KERN_INFO PFX
			       "timeout value invalid, using %d\n", timeout);
		}

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

		printk(KERN_INFO PFX
		       "initialized (timeout=%ds, nowayout=%d)\n",
		       timeout, nowayout);
		break;

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

	default:
		printk(KERN_INFO PFX "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;

	printk(KERN_INFO PFX "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);
	printk(KERN_INFO PFX "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
	12	#define DRV_NAME "wdt"
	13	#define DRV_VERSION "0.01"
	14	#define PFX DRV_NAME ": "
	15
	16	#include <linux/bug.h>
	17	#include <linux/errno.h>
	18	#include <linux/fs.h>
	19	#include <linux/hrtimer.h>
	20	#include <linux/kernel.h>
	21	#include <linux/ktime.h>
	22	#include <linux/init.h>
	23	#include <linux/miscdevice.h>
	24	#include <linux/module.h>
	25	#include <linux/moduleparam.h>
	26	#include <linux/platform_device.h>
	27	#include <linux/spinlock.h>
	28	#include <linux/uaccess.h>
	29	#include <linux/watchdog.h>
	30	#include <xen/xen.h>
	31	#include <asm/xen/hypercall.h>
	32	#include <xen/interface/sched.h>
	33
	34	static struct platform_device *platform_device;
	35	static DEFINE_SPINLOCK(wdt_lock);
	36	static struct sched_watchdog wdt;
	37	static __kernel_time_t wdt_expires;
	38	static bool is_active, expect_release;
	39
	40	#define WATCHDOG_TIMEOUT 60 /* in seconds */
	41	static unsigned int timeout = WATCHDOG_TIMEOUT;
	42	module_param(timeout, uint, S_IRUGO);
	43	MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
	44	"(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
	45
	46	static bool nowayout = WATCHDOG_NOWAYOUT;
	47	module_param(nowayout, bool, S_IRUGO);
	48	MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
	49	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
	50
	51	static inline __kernel_time_t set_timeout(void)
	52	{
	53	wdt.timeout = timeout;
	54	return ktime_to_timespec(ktime_get()).tv_sec + timeout;
	55	}
	56
	57	static int xen_wdt_start(void)
	58	{
	59	__kernel_time_t expires;
	60	int err;
	61
	62	spin_lock(&wdt_lock);
	63
	64	expires = set_timeout();
65	if (!wdt.id)
66	err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
67	else
68	err = -EBUSY;
69	if (err > 0) {
70	wdt.id = err;
71	wdt_expires = expires;
72	err = 0;
73	} else
74	BUG_ON(!err);
75
76	spin_unlock(&wdt_lock);
77
78	return err;
79	}
80
81	static int xen_wdt_stop(void)
82	{
83	int err = 0;
84
85	spin_lock(&wdt_lock);
86
87	wdt.timeout = 0;
88	if (wdt.id)
89	err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
90	if (!err)
91	wdt.id = 0;
92
93	spin_unlock(&wdt_lock);
94
95	return err;
96	}
97
98	static int xen_wdt_kick(void)
99	{
100	__kernel_time_t expires;
101	int err;
102
103	spin_lock(&wdt_lock);
104
105	expires = set_timeout();
106	if (wdt.id)
107	err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
108	else
109	err = -ENXIO;
110	if (!err)
111	wdt_expires = expires;
112
113	spin_unlock(&wdt_lock);
114
115	return err;
116	}
117
118	static int xen_wdt_open(struct inode inode, struct file file)
119	{
120	int err;
121
122	/* /dev/watchdog can only be opened once */
123	if (xchg(&is_active, true))
124	return -EBUSY;
125
126	err = xen_wdt_start();
127	if (err == -EBUSY)
128	err = xen_wdt_kick();
129	return err ?: nonseekable_open(inode, file);
130	}
131
132	static int xen_wdt_release(struct inode inode, struct file file)
133	{
134	if (expect_release)
135	xen_wdt_stop();
136	else {
137	printk(KERN_CRIT PFX
138	"unexpected close, not stopping watchdog!\n");
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;
254	printk(KERN_INFO PFX
255	"timeout value invalid, using %d\n", timeout);
256	}
257
258	ret = misc_register(&xen_wdt_miscdev);
259	if (ret) {
260	printk(KERN_ERR PFX
261	"cannot register miscdev on minor=%d (%d)\n",
262	WATCHDOG_MINOR, ret);
263	break;
264	}
265
266	printk(KERN_INFO PFX
267	"initialized (timeout=%ds, nowayout=%d)\n",
268	timeout, nowayout);
269	break;
270
271	case -ENOSYS:
272	printk(KERN_INFO PFX "not supported\n");
273	ret = -ENODEV;
274	break;
275
276	default:
277	printk(KERN_INFO PFX "bogus return value %d\n", ret);
278	break;
279	}
280
281	return ret;
282	}
283
284	static int __devexit xen_wdt_remove(struct platform_device *dev)
285	{
286	/* Stop the timer before we leave */
287	if (!nowayout)
288	xen_wdt_stop();
289
290	misc_deregister(&xen_wdt_miscdev);
291
292	return 0;
293	}
294
295	static void xen_wdt_shutdown(struct platform_device *dev)
296	{
297	xen_wdt_stop();
298	}
299
300	static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
301	{
302	return xen_wdt_stop();
303	}
304
305	static int xen_wdt_resume(struct platform_device *dev)
306	{
307	return xen_wdt_start();
308	}
309
310	static struct platform_driver xen_wdt_driver = {
311	.probe = xen_wdt_probe,
312	.remove = __devexit_p(xen_wdt_remove),
313	.shutdown = xen_wdt_shutdown,
314	.suspend = xen_wdt_suspend,
315	.resume = xen_wdt_resume,
316	.driver = {
317	.owner = THIS_MODULE,
318	.name = DRV_NAME,
319	},
320	};
321
322	static int __init xen_wdt_init_module(void)
323	{
324	int err;
325
326	if (!xen_domain())
327	return -ENODEV;
328
329	printk(KERN_INFO PFX "Xen WatchDog Timer Driver v%s\n", DRV_VERSION);
330
331	err = platform_driver_register(&xen_wdt_driver);
332	if (err)
333	return err;
334
335	platform_device = platform_device_register_simple(DRV_NAME,
336	-1, NULL, 0);
337	if (IS_ERR(platform_device)) {
338	err = PTR_ERR(platform_device);
339	platform_driver_unregister(&xen_wdt_driver);
340	}
341
342	return err;
343	}
344
345	static void __exit xen_wdt_cleanup_module(void)
346	{
347	platform_device_unregister(platform_device);
348	platform_driver_unregister(&xen_wdt_driver);
349	printk(KERN_INFO PFX "module unloaded\n");
350	}
351
352	module_init(xen_wdt_init_module);
353	module_exit(xen_wdt_cleanup_module);
354
355	MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>");
356	MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
357	MODULE_VERSION(DRV_VERSION);
358	MODULE_LICENSE("GPL");
359	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);