[GitHub/mt8127/android_kernel_alcatel_ttab.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)
{
	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 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 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         = 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	{
38c484fa JB	135	int err = 0;
38c484fa JB	136
066d6c7f	137	if (expect_release)
38c484fa	138	err = xen_wdt_stop();
066d6c7f	139	else {
27c766aa	140	pr_crit("unexpected close, not stopping watchdog!\n");
066d6c7f JB	141	xen_wdt_kick();
066d6c7f JB	142	}
38c484fa	143	is_active = err;
066d6c7f	144	expect_release = false;
38c484fa	145	return err;
066d6c7f JB	146	}
	147
	148	static ssize_t xen_wdt_write(struct file file, const char __user data,
	149	size_t len, loff_t *ppos)
	150	{
	151	/* See if we got the magic character 'V' and reload the timer */
	152	if (len) {
	153	if (!nowayout) {
	154	size_t i;
	155
	156	/* in case it was set long ago */
	157	expect_release = false;
	158
	159	/* scan to see whether or not we got the magic
	160	character */
	161	for (i = 0; i != len; i++) {
	162	char c;
	163	if (get_user(c, data + i))
	164	return -EFAULT;
	165	if (c == 'V')
	166	expect_release = true;
	167	}
	168	}
	169
	170	/* someone wrote to us, we should reload the timer */
	171	xen_wdt_kick();
	172	}
	173	return len;
	174	}
	175
	176	static long xen_wdt_ioctl(struct file *file, unsigned int cmd,
	177	unsigned long arg)
	178	{
	179	int new_options, retval = -EINVAL;
	180	int new_timeout;
	181	int __user argp = (void __user )arg;
	182	static const struct watchdog_info ident = {
	183	.options = WDIOF_SETTIMEOUT \| WDIOF_MAGICCLOSE,
	184	.firmware_version = 0,
	185	.identity = DRV_NAME,
	186	};
	187
	188	switch (cmd) {
	189	case WDIOC_GETSUPPORT:
	190	return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
	191
	192	case WDIOC_GETSTATUS:
	193	case WDIOC_GETBOOTSTATUS:
	194	return put_user(0, argp);
	195
	196	case WDIOC_SETOPTIONS:
	197	if (get_user(new_options, argp))
	198	return -EFAULT;
	199
	200	if (new_options & WDIOS_DISABLECARD)
	201	retval = xen_wdt_stop();
	202	if (new_options & WDIOS_ENABLECARD) {
	203	retval = xen_wdt_start();
	204	if (retval == -EBUSY)
	205	retval = xen_wdt_kick();
	206	}
	207	return retval;
	208
	209	case WDIOC_KEEPALIVE:
210	xen_wdt_kick();
211	return 0;
212
213	case WDIOC_SETTIMEOUT:
214	if (get_user(new_timeout, argp))
215	return -EFAULT;
216	if (!new_timeout)
217	return -EINVAL;
218	timeout = new_timeout;
219	xen_wdt_kick();
220	/* fall through */
221	case WDIOC_GETTIMEOUT:
222	return put_user(timeout, argp);
223
224	case WDIOC_GETTIMELEFT:
225	retval = wdt_expires - ktime_to_timespec(ktime_get()).tv_sec;
226	return put_user(retval, argp);
227	}
228
229	return -ENOTTY;
230	}
231
232	static const struct file_operations xen_wdt_fops = {
233	.owner = THIS_MODULE,
234	.llseek = no_llseek,
235	.write = xen_wdt_write,
236	.unlocked_ioctl = xen_wdt_ioctl,
237	.open = xen_wdt_open,
238	.release = xen_wdt_release,
239	};
240
241	static struct miscdevice xen_wdt_miscdev = {
242	.minor = WATCHDOG_MINOR,
243	.name = "watchdog",
244	.fops = &xen_wdt_fops,
245	};
246
2d991a16	247	static int xen_wdt_probe(struct platform_device *dev)
066d6c7f JB	248	{
	249	struct sched_watchdog wd = { .id = ~0 };
	250	int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
	251
	252	switch (ret) {
	253	case -EINVAL:
	254	if (!timeout) {
	255	timeout = WATCHDOG_TIMEOUT;
27c766aa	256	pr_info("timeout value invalid, using %d\n", timeout);
066d6c7f JB	257	}
	258
	259	ret = misc_register(&xen_wdt_miscdev);
	260	if (ret) {
27c766aa	261	pr_err("cannot register miscdev on minor=%d (%d)\n",
066d6c7f JB	262	WATCHDOG_MINOR, ret);
	263	break;
	264	}
	265
27c766aa JP	266	pr_info("initialized (timeout=%ds, nowayout=%d)\n",
27c766aa JP	267	timeout, nowayout);
066d6c7f JB	268	break;
	269
	270	case -ENOSYS:
27c766aa	271	pr_info("not supported\n");
066d6c7f JB	272	ret = -ENODEV;
	273	break;
	274
	275	default:
27c766aa	276	pr_info("bogus return value %d\n", ret);
066d6c7f JB	277	break;
	278	}
	279
	280	return ret;
	281	}
	282
4b12b896	283	static int xen_wdt_remove(struct platform_device *dev)
066d6c7f JB	284	{
	285	/* Stop the timer before we leave */
	286	if (!nowayout)
	287	xen_wdt_stop();
	288
	289	misc_deregister(&xen_wdt_miscdev);
	290
	291	return 0;
	292	}
	293
	294	static void xen_wdt_shutdown(struct platform_device *dev)
	295	{
	296	xen_wdt_stop();
	297	}
	298
	299	static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
	300	{
83448bf7 JB	301	typeof(wdt.id) id = wdt.id;
	302	int rc = xen_wdt_stop();
	303
	304	wdt.id = id;
	305	return rc;
066d6c7f JB	306	}
	307
	308	static int xen_wdt_resume(struct platform_device *dev)
	309	{
83448bf7 JB	310	if (!wdt.id)
	311	return 0;
	312	wdt.id = 0;
066d6c7f JB	313	return xen_wdt_start();
	314	}
	315
	316	static struct platform_driver xen_wdt_driver = {
	317	.probe = xen_wdt_probe,
82268714	318	.remove = xen_wdt_remove,
066d6c7f JB	319	.shutdown = xen_wdt_shutdown,
	320	.suspend = xen_wdt_suspend,
	321	.resume = xen_wdt_resume,
	322	.driver = {
	323	.owner = THIS_MODULE,
	324	.name = DRV_NAME,
	325	},
	326	};
	327
	328	static int __init xen_wdt_init_module(void)
	329	{
	330	int err;
	331
	332	if (!xen_domain())
	333	return -ENODEV;
	334
27c766aa	335	pr_info("Xen WatchDog Timer Driver v%s\n", DRV_VERSION);
066d6c7f JB	336
	337	err = platform_driver_register(&xen_wdt_driver);
	338	if (err)
	339	return err;
	340
	341	platform_device = platform_device_register_simple(DRV_NAME,
	342	-1, NULL, 0);
	343	if (IS_ERR(platform_device)) {
	344	err = PTR_ERR(platform_device);
	345	platform_driver_unregister(&xen_wdt_driver);
	346	}
	347
	348	return err;
	349	}
	350
	351	static void __exit xen_wdt_cleanup_module(void)
	352	{
	353	platform_device_unregister(platform_device);
	354	platform_driver_unregister(&xen_wdt_driver);
27c766aa	355	pr_info("module unloaded\n");
066d6c7f JB	356	}
	357
	358	module_init(xen_wdt_init_module);
	359	module_exit(xen_wdt_cleanup_module);
	360
	361	MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>");
	362	MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
	363	MODULE_VERSION(DRV_VERSION);
	364	MODULE_LICENSE("GPL");
	365	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);