[linux-2.6-block.git] / drivers / s390 / char / vmwatchdog.c

/*
 * Watchdog implementation based on z/VM Watchdog Timer API
 *
 * Copyright IBM Corp. 2004,2009
 *
 * The user space watchdog daemon can use this driver as
 * /dev/vmwatchdog to have z/VM execute the specified CP
 * command when the timeout expires. The default command is
 * "IPL", which which cause an immediate reboot.
 */
#define KMSG_COMPONENT "vmwatchdog"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/suspend.h>
#include <linux/watchdog.h>

#include <asm/ebcdic.h>
#include <asm/io.h>
#include <asm/uaccess.h>

#define MAX_CMDLEN 240
#define MIN_INTERVAL 15
static char vmwdt_cmd[MAX_CMDLEN] = "IPL";
static int vmwdt_conceal;

static int vmwdt_nowayout = WATCHDOG_NOWAYOUT;

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
MODULE_DESCRIPTION("z/VM Watchdog Timer");
module_param_string(cmd, vmwdt_cmd, MAX_CMDLEN, 0644);
MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers");
module_param_named(conceal, vmwdt_conceal, bool, 0644);
MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog "
		" is active");
module_param_named(nowayout, vmwdt_nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started"
		" (default=CONFIG_WATCHDOG_NOWAYOUT)");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

static unsigned int vmwdt_interval = 60;
static unsigned long vmwdt_is_open;
static int vmwdt_expect_close;

static DEFINE_MUTEX(vmwdt_mutex);

#define VMWDT_OPEN	0	/* devnode is open or suspend in progress */
#define VMWDT_RUNNING	1	/* The watchdog is armed */

enum vmwdt_func {
	/* function codes */
	wdt_init   = 0,
	wdt_change = 1,
	wdt_cancel = 2,
	/* flags */
	wdt_conceal = 0x80000000,
};

static int __diag288(enum vmwdt_func func, unsigned int timeout,
			    char *cmd, size_t len)
{
	register unsigned long __func asm("2") = func;
	register unsigned long __timeout asm("3") = timeout;
	register unsigned long __cmdp asm("4") = virt_to_phys(cmd);
	register unsigned long __cmdl asm("5") = len;
	int err;

	err = -EINVAL;
	asm volatile(
		"	diag	%1,%3,0x288\n"
		"0:	la	%0,0\n"
		"1:\n"
		EX_TABLE(0b,1b)
		: "+d" (err) : "d"(__func), "d"(__timeout),
		  "d"(__cmdp), "d"(__cmdl) : "1", "cc");
	return err;
}

static int vmwdt_keepalive(void)
{
	/* we allocate new memory every time to avoid having
	 * to track the state. static allocation is not an
	 * option since that might not be contiguous in real
	 * storage in case of a modular build */
	static char *ebc_cmd;
	size_t len;
	int ret;
	unsigned int func;

	ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
	if (!ebc_cmd)
		return -ENOMEM;

	len = strlcpy(ebc_cmd, vmwdt_cmd, MAX_CMDLEN);
	ASCEBC(ebc_cmd, MAX_CMDLEN);
	EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);

	func = vmwdt_conceal ? (wdt_init | wdt_conceal) : wdt_init;
	set_bit(VMWDT_RUNNING, &vmwdt_is_open);
	ret = __diag288(func, vmwdt_interval, ebc_cmd, len);
	WARN_ON(ret != 0);
	kfree(ebc_cmd);
	return ret;
}

static int vmwdt_disable(void)
{
	int ret = __diag288(wdt_cancel, 0, "", 0);
	WARN_ON(ret != 0);
	clear_bit(VMWDT_RUNNING, &vmwdt_is_open);
	return ret;
}

static int __init vmwdt_probe(void)
{
	/* there is no real way to see if the watchdog is supported,
	 * so we try initializing it with a NOP command ("BEGIN")
	 * that won't cause any harm even if the following disable
	 * fails for some reason */
	static char __initdata ebc_begin[] = {
		194, 197, 199, 201, 213
	};
	if (__diag288(wdt_init, 15, ebc_begin, sizeof(ebc_begin)) != 0)
		return -EINVAL;
	return vmwdt_disable();
}

static int vmwdt_open(struct inode *i, struct file *f)
{
	int ret;
	if (test_and_set_bit(VMWDT_OPEN, &vmwdt_is_open))
		return -EBUSY;
	ret = vmwdt_keepalive();
	if (ret)
		clear_bit(VMWDT_OPEN, &vmwdt_is_open);
	return ret ? ret : nonseekable_open(i, f);
}

static int vmwdt_close(struct inode *i, struct file *f)
{
	if (vmwdt_expect_close == 42)
		vmwdt_disable();
	vmwdt_expect_close = 0;
	clear_bit(VMWDT_OPEN, &vmwdt_is_open);
	return 0;
}

static struct watchdog_info vmwdt_info = {
	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
	.firmware_version = 0,
	.identity = "z/VM Watchdog Timer",
};

static int __vmwdt_ioctl(unsigned int cmd, unsigned long arg)
{
	switch (cmd) {
	case WDIOC_GETSUPPORT:
		if (copy_to_user((void __user *)arg, &vmwdt_info,
					sizeof(vmwdt_info)))
			return -EFAULT;
		return 0;
	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		return put_user(0, (int __user *)arg);
	case WDIOC_GETTEMP:
		return -EINVAL;
	case WDIOC_SETOPTIONS:
		{
			int options, ret;
			if (get_user(options, (int __user *)arg))
				return -EFAULT;
			ret = -EINVAL;
			if (options & WDIOS_DISABLECARD) {
				ret = vmwdt_disable();
				if (ret)
					return ret;
			}
			if (options & WDIOS_ENABLECARD) {
				ret = vmwdt_keepalive();
			}
			return ret;
		}
	case WDIOC_GETTIMEOUT:
		return put_user(vmwdt_interval, (int __user *)arg);
	case WDIOC_SETTIMEOUT:
		{
			int interval;
			if (get_user(interval, (int __user *)arg))
				return -EFAULT;
			if (interval < MIN_INTERVAL)
				return -EINVAL;
			vmwdt_interval = interval;
		}
		return vmwdt_keepalive();
	case WDIOC_KEEPALIVE:
		return vmwdt_keepalive();
	}
	return -EINVAL;
}

static long vmwdt_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
{
	int rc;

	mutex_lock(&vmwdt_mutex);
	rc = __vmwdt_ioctl(cmd, arg);
	mutex_unlock(&vmwdt_mutex);
	return (long) rc;
}

static ssize_t vmwdt_write(struct file *f, const char __user *buf,
				size_t count, loff_t *ppos)
{
	if(count) {
		if (!vmwdt_nowayout) {
			size_t i;

			/* note: just in case someone wrote the magic character
			 * five months ago... */
			vmwdt_expect_close = 0;

			for (i = 0; i != count; i++) {
				char c;
				if (get_user(c, buf+i))
					return -EFAULT;
				if (c == 'V')
					vmwdt_expect_close = 42;
			}
		}
		/* someone wrote to us, we should restart timer */
		vmwdt_keepalive();
	}
	return count;
}

static int vmwdt_resume(void)
{
	clear_bit(VMWDT_OPEN, &vmwdt_is_open);
	return NOTIFY_DONE;
}

/*
 * It makes no sense to go into suspend while the watchdog is running.
 * Depending on the memory size, the watchdog might trigger, while we
 * are still saving the memory.
 * We reuse the open flag to ensure that suspend and watchdog open are
 * exclusive operations
 */
static int vmwdt_suspend(void)
{
	if (test_and_set_bit(VMWDT_OPEN, &vmwdt_is_open)) {
		pr_err("The system cannot be suspended while the watchdog"
			" is in use\n");
		return NOTIFY_BAD;
	}
	if (test_bit(VMWDT_RUNNING, &vmwdt_is_open)) {
		clear_bit(VMWDT_OPEN, &vmwdt_is_open);
		pr_err("The system cannot be suspended while the watchdog"
			" is running\n");
		return NOTIFY_BAD;
	}
	return NOTIFY_DONE;
}

/*
 * This function is called for suspend and resume.
 */
static int vmwdt_power_event(struct notifier_block *this, unsigned long event,
			     void *ptr)
{
	switch (event) {
	case PM_POST_HIBERNATION:
	case PM_POST_SUSPEND:
		return vmwdt_resume();
	case PM_HIBERNATION_PREPARE:
	case PM_SUSPEND_PREPARE:
		return vmwdt_suspend();
	default:
		return NOTIFY_DONE;
	}
}

static struct notifier_block vmwdt_power_notifier = {
	.notifier_call = vmwdt_power_event,
};

static const struct file_operations vmwdt_fops = {
	.open    = &vmwdt_open,
	.release = &vmwdt_close,
	.unlocked_ioctl = &vmwdt_ioctl,
	.write   = &vmwdt_write,
	.owner   = THIS_MODULE,
};

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

static int __init vmwdt_init(void)
{
	int ret;

	ret = vmwdt_probe();
	if (ret)
		return ret;
	ret = register_pm_notifier(&vmwdt_power_notifier);
	if (ret)
		return ret;
	/*
	 * misc_register() has to be the last action in module_init(), because
	 * file operations will be available right after this.
	 */
	ret = misc_register(&vmwdt_dev);
	if (ret) {
		unregister_pm_notifier(&vmwdt_power_notifier);
		return ret;
	}
	return 0;
}
module_init(vmwdt_init);

static void __exit vmwdt_exit(void)
{
	unregister_pm_notifier(&vmwdt_power_notifier);
	misc_deregister(&vmwdt_dev);
}
module_exit(vmwdt_exit);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Watchdog implementation based on z/VM Watchdog Timer API
	3	*
58872d5f CB	4	* Copyright IBM Corp. 2004,2009
58872d5f CB	5	*
1da177e4 LT	6	* The user space watchdog daemon can use this driver as
	7	* /dev/vmwatchdog to have z/VM execute the specified CP
	8	* command when the timeout expires. The default command is
	9	* "IPL", which which cause an immediate reboot.
	10	*/
58872d5f CB	11	#define KMSG_COMPONENT "vmwatchdog"
	12	#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
	13
1da177e4 LT	14	#include <linux/init.h>
	15	#include <linux/fs.h>
	16	#include <linux/kernel.h>
	17	#include <linux/miscdevice.h>
	18	#include <linux/module.h>
	19	#include <linux/moduleparam.h>
5a0e3ad6	20	#include <linux/slab.h>
58872d5f	21	#include <linux/suspend.h>
1da177e4 LT	22	#include <linux/watchdog.h>
	23
	24	#include <asm/ebcdic.h>
	25	#include <asm/io.h>
	26	#include <asm/uaccess.h>
	27
	28	#define MAX_CMDLEN 240
	29	#define MIN_INTERVAL 15
	30	static char vmwdt_cmd[MAX_CMDLEN] = "IPL";
	31	static int vmwdt_conceal;
	32
4bfdf378	33	static int vmwdt_nowayout = WATCHDOG_NOWAYOUT;
1da177e4 LT	34
	35	MODULE_LICENSE("GPL");
	36	MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
	37	MODULE_DESCRIPTION("z/VM Watchdog Timer");
	38	module_param_string(cmd, vmwdt_cmd, MAX_CMDLEN, 0644);
	39	MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers");
	40	module_param_named(conceal, vmwdt_conceal, bool, 0644);
	41	MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog "
	42	" is active");
	43	module_param_named(nowayout, vmwdt_nowayout, bool, 0);
	44	MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started"
	45	" (default=CONFIG_WATCHDOG_NOWAYOUT)");
	46	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
	47
	48	static unsigned int vmwdt_interval = 60;
	49	static unsigned long vmwdt_is_open;
	50	static int vmwdt_expect_close;
	51
feb5c5a4 GS	52	static DEFINE_MUTEX(vmwdt_mutex);
feb5c5a4 GS	53
58872d5f CB	54	#define VMWDT_OPEN 0 /* devnode is open or suspend in progress */
	55	#define VMWDT_RUNNING 1 /* The watchdog is armed */
	56
1da177e4 LT	57	enum vmwdt_func {
	58	/* function codes */
	59	wdt_init = 0,
	60	wdt_change = 1,
	61	wdt_cancel = 2,
	62	/* flags */
	63	wdt_conceal = 0x80000000,
	64	};
	65
	66	static int __diag288(enum vmwdt_func func, unsigned int timeout,
	67	char *cmd, size_t len)
	68	{
94c12cc7 MS	69	register unsigned long __func asm("2") = func;
	70	register unsigned long __timeout asm("3") = timeout;
	71	register unsigned long __cmdp asm("4") = virt_to_phys(cmd);
	72	register unsigned long __cmdl asm("5") = len;
1da177e4 LT	73	int err;
1da177e4 LT	74
94c12cc7 MS	75	err = -EINVAL;
	76	asm volatile(
	77	" diag %1,%3,0x288\n"
	78	"0: la %0,0\n"
	79	"1:\n"
	80	EX_TABLE(0b,1b)
2b12f996 HC	81	: "+d" (err) : "d"(__func), "d"(__timeout),
2b12f996 HC	82	"d"(__cmdp), "d"(__cmdl) : "1", "cc");
1da177e4 LT	83	return err;
	84	}
	85
	86	static int vmwdt_keepalive(void)
	87	{
	88	/* we allocate new memory every time to avoid having
	89	* to track the state. static allocation is not an
	90	* option since that might not be contiguous in real
	91	* storage in case of a modular build */
	92	static char *ebc_cmd;
	93	size_t len;
	94	int ret;
	95	unsigned int func;
	96
	97	ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
	98	if (!ebc_cmd)
	99	return -ENOMEM;
	100
	101	len = strlcpy(ebc_cmd, vmwdt_cmd, MAX_CMDLEN);
	102	ASCEBC(ebc_cmd, MAX_CMDLEN);
	103	EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
	104
	105	func = vmwdt_conceal ? (wdt_init \| wdt_conceal) : wdt_init;
58872d5f	106	set_bit(VMWDT_RUNNING, &vmwdt_is_open);
1da177e4	107	ret = __diag288(func, vmwdt_interval, ebc_cmd, len);
0d130066	108	WARN_ON(ret != 0);
1da177e4	109	kfree(ebc_cmd);
1da177e4 LT	110	return ret;
	111	}
	112
	113	static int vmwdt_disable(void)
	114	{
	115	int ret = __diag288(wdt_cancel, 0, "", 0);
0d130066	116	WARN_ON(ret != 0);
58872d5f	117	clear_bit(VMWDT_RUNNING, &vmwdt_is_open);
1da177e4 LT	118	return ret;
	119	}
	120
	121	static int __init vmwdt_probe(void)
	122	{
	123	/* there is no real way to see if the watchdog is supported,
	124	* so we try initializing it with a NOP command ("BEGIN")
	125	* that won't cause any harm even if the following disable
	126	* fails for some reason */
	127	static char __initdata ebc_begin[] = {
	128	194, 197, 199, 201, 213
	129	};
0d130066	130	if (__diag288(wdt_init, 15, ebc_begin, sizeof(ebc_begin)) != 0)
1da177e4	131	return -EINVAL;
1da177e4 LT	132	return vmwdt_disable();
	133	}
	134
	135	static int vmwdt_open(struct inode i, struct file f)
	136	{
	137	int ret;
feb5c5a4	138	if (test_and_set_bit(VMWDT_OPEN, &vmwdt_is_open))
1da177e4 LT	139	return -EBUSY;
	140	ret = vmwdt_keepalive();
	141	if (ret)
58872d5f	142	clear_bit(VMWDT_OPEN, &vmwdt_is_open);
1da177e4 LT	143	return ret ? ret : nonseekable_open(i, f);
	144	}
	145
	146	static int vmwdt_close(struct inode i, struct file f)
	147	{
	148	if (vmwdt_expect_close == 42)
	149	vmwdt_disable();
	150	vmwdt_expect_close = 0;
58872d5f	151	clear_bit(VMWDT_OPEN, &vmwdt_is_open);
1da177e4 LT	152	return 0;
	153	}
	154
	155	static struct watchdog_info vmwdt_info = {
	156	.options = WDIOF_SETTIMEOUT \| WDIOF_KEEPALIVEPING \| WDIOF_MAGICCLOSE,
	157	.firmware_version = 0,
	158	.identity = "z/VM Watchdog Timer",
	159	};
	160
feb5c5a4	161	static int __vmwdt_ioctl(unsigned int cmd, unsigned long arg)
1da177e4 LT	162	{
	163	switch (cmd) {
	164	case WDIOC_GETSUPPORT:
	165	if (copy_to_user((void __user *)arg, &vmwdt_info,
	166	sizeof(vmwdt_info)))
	167	return -EFAULT;
	168	return 0;
	169	case WDIOC_GETSTATUS:
	170	case WDIOC_GETBOOTSTATUS:
d2c993d8	171	return put_user(0, (int __user *)arg);
1da177e4 LT	172	case WDIOC_GETTEMP:
	173	return -EINVAL;
	174	case WDIOC_SETOPTIONS:
	175	{
	176	int options, ret;
	177	if (get_user(options, (int __user *)arg))
	178	return -EFAULT;
	179	ret = -EINVAL;
	180	if (options & WDIOS_DISABLECARD) {
	181	ret = vmwdt_disable();
	182	if (ret)
	183	return ret;
	184	}
	185	if (options & WDIOS_ENABLECARD) {
	186	ret = vmwdt_keepalive();
	187	}
	188	return ret;
	189	}
	190	case WDIOC_GETTIMEOUT:
	191	return put_user(vmwdt_interval, (int __user *)arg);
	192	case WDIOC_SETTIMEOUT:
	193	{
	194	int interval;
	195	if (get_user(interval, (int __user *)arg))
	196	return -EFAULT;
	197	if (interval < MIN_INTERVAL)
	198	return -EINVAL;
	199	vmwdt_interval = interval;
	200	}
	201	return vmwdt_keepalive();
	202	case WDIOC_KEEPALIVE:
	203	return vmwdt_keepalive();
	204	}
1da177e4 LT	205	return -EINVAL;
	206	}
	207
feb5c5a4 GS	208	static long vmwdt_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
	209	{
	210	int rc;
	211
	212	mutex_lock(&vmwdt_mutex);
	213	rc = __vmwdt_ioctl(cmd, arg);
	214	mutex_unlock(&vmwdt_mutex);
	215	return (long) rc;
	216	}
	217
1da177e4 LT	218	static ssize_t vmwdt_write(struct file f, const char __user buf,
	219	size_t count, loff_t *ppos)
	220	{
	221	if(count) {
	222	if (!vmwdt_nowayout) {
	223	size_t i;
	224
	225	/* note: just in case someone wrote the magic character
	226	* five months ago... */
	227	vmwdt_expect_close = 0;
	228
	229	for (i = 0; i != count; i++) {
	230	char c;
	231	if (get_user(c, buf+i))
	232	return -EFAULT;
	233	if (c == 'V')
	234	vmwdt_expect_close = 42;
	235	}
	236	}
	237	/* someone wrote to us, we should restart timer */
	238	vmwdt_keepalive();
	239	}
	240	return count;
	241	}
	242
58872d5f CB	243	static int vmwdt_resume(void)
	244	{
	245	clear_bit(VMWDT_OPEN, &vmwdt_is_open);
	246	return NOTIFY_DONE;
	247	}
	248
	249	/*
	250	* It makes no sense to go into suspend while the watchdog is running.
	251	* Depending on the memory size, the watchdog might trigger, while we
	252	* are still saving the memory.
	253	* We reuse the open flag to ensure that suspend and watchdog open are
	254	* exclusive operations
	255	*/
	256	static int vmwdt_suspend(void)
	257	{
	258	if (test_and_set_bit(VMWDT_OPEN, &vmwdt_is_open)) {
2c48c4d6 CB	259	pr_err("The system cannot be suspended while the watchdog"
2c48c4d6 CB	260	" is in use\n");
58872d5f CB	261	return NOTIFY_BAD;
	262	}
	263	if (test_bit(VMWDT_RUNNING, &vmwdt_is_open)) {
	264	clear_bit(VMWDT_OPEN, &vmwdt_is_open);
2c48c4d6 CB	265	pr_err("The system cannot be suspended while the watchdog"
2c48c4d6 CB	266	" is running\n");
58872d5f CB	267	return NOTIFY_BAD;
	268	}
	269	return NOTIFY_DONE;
	270	}
	271
	272	/*
	273	* This function is called for suspend and resume.
	274	*/
	275	static int vmwdt_power_event(struct notifier_block *this, unsigned long event,
	276	void *ptr)
	277	{
	278	switch (event) {
	279	case PM_POST_HIBERNATION:
	280	case PM_POST_SUSPEND:
	281	return vmwdt_resume();
	282	case PM_HIBERNATION_PREPARE:
	283	case PM_SUSPEND_PREPARE:
	284	return vmwdt_suspend();
	285	default:
	286	return NOTIFY_DONE;
	287	}
	288	}
	289
	290	static struct notifier_block vmwdt_power_notifier = {
	291	.notifier_call = vmwdt_power_event,
	292	};
	293
d54b1fdb	294	static const struct file_operations vmwdt_fops = {
1da177e4 LT	295	.open = &vmwdt_open,
1da177e4 LT	296	.release = &vmwdt_close,
feb5c5a4	297	.unlocked_ioctl = &vmwdt_ioctl,
1da177e4 LT	298	.write = &vmwdt_write,
	299	.owner = THIS_MODULE,
	300	};
	301
	302	static struct miscdevice vmwdt_dev = {
	303	.minor = WATCHDOG_MINOR,
	304	.name = "watchdog",
	305	.fops = &vmwdt_fops,
	306	};
	307
	308	static int __init vmwdt_init(void)
	309	{
	310	int ret;
	311
	312	ret = vmwdt_probe();
	313	if (ret)
	314	return ret;
58872d5f CB	315	ret = register_pm_notifier(&vmwdt_power_notifier);
	316	if (ret)
	317	return ret;
feb5c5a4 GS	318	/*
	319	* misc_register() has to be the last action in module_init(), because
	320	* file operations will be available right after this.
	321	*/
58872d5f CB	322	ret = misc_register(&vmwdt_dev);
	323	if (ret) {
	324	unregister_pm_notifier(&vmwdt_power_notifier);
	325	return ret;
	326	}
	327	return 0;
1da177e4 LT	328	}
	329	module_init(vmwdt_init);
	330
	331	static void __exit vmwdt_exit(void)
	332	{
58872d5f CB	333	unregister_pm_notifier(&vmwdt_power_notifier);
58872d5f CB	334	misc_deregister(&vmwdt_dev);
1da177e4 LT	335	}
1da177e4 LT	336	module_exit(vmwdt_exit);