[linux-2.6-block.git] / drivers / watchdog / diag288_wdt.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Watchdog driver for z/VM and LPAR using the diag 288 interface.
 *
 * Under z/VM, expiration of the watchdog will send a "system restart" command
 * to CP.
 *
 * The command can be altered using the module parameter "cmd". This is
 * not recommended because it's only supported on z/VM but not whith LPAR.
 *
 * On LPAR, the watchdog will always trigger a system restart. the module
 * paramter cmd is meaningless here.
 *
 *
 * Copyright IBM Corp. 2004, 2013
 * Author(s): Arnd Bergmann (arndb@de.ibm.com)
 *	      Philipp Hachtmann (phacht@de.ibm.com)
 *
 */

#define KMSG_COMPONENT "diag288_wdt"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/suspend.h>
#include <asm/ebcdic.h>
#include <asm/diag.h>
#include <linux/io.h>
#include <linux/uaccess.h>

#define MAX_CMDLEN 240
#define DEFAULT_CMD "SYSTEM RESTART"

#define MIN_INTERVAL 15     /* Minimal time supported by diag88 */
#define MAX_INTERVAL 3600   /* One hour should be enough - pure estimation */

#define WDT_DEFAULT_TIMEOUT 30

/* Function codes - init, change, cancel */
#define WDT_FUNC_INIT 0
#define WDT_FUNC_CHANGE 1
#define WDT_FUNC_CANCEL 2
#define WDT_FUNC_CONCEAL 0x80000000

/* Action codes for LPAR watchdog */
#define LPARWDT_RESTART 0

static char wdt_cmd[MAX_CMDLEN] = DEFAULT_CMD;
static bool conceal_on;
static bool nowayout_info = WATCHDOG_NOWAYOUT;

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
MODULE_AUTHOR("Philipp Hachtmann <phacht@de.ibm.com>");

MODULE_DESCRIPTION("System z diag288  Watchdog Timer");

module_param_string(cmd, wdt_cmd, MAX_CMDLEN, 0644);
MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers (z/VM only)");

module_param_named(conceal, conceal_on, bool, 0644);
MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog is active (z/VM only)");

module_param_named(nowayout, nowayout_info, bool, 0444);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default = CONFIG_WATCHDOG_NOWAYOUT)");

MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS("vmwatchdog");

static int __diag288(unsigned int func, unsigned int timeout,
		     unsigned long action, unsigned int len)
{
	register unsigned long __func asm("2") = func;
	register unsigned long __timeout asm("3") = timeout;
	register unsigned long __action asm("4") = action;
	register unsigned long __len 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"(__action), "d"(__len) : "1", "cc");
	return err;
}

static int __diag288_vm(unsigned int  func, unsigned int timeout,
			char *cmd, size_t len)
{
	diag_stat_inc(DIAG_STAT_X288);
	return __diag288(func, timeout, virt_to_phys(cmd), len);
}

static int __diag288_lpar(unsigned int func, unsigned int timeout,
			  unsigned long action)
{
	diag_stat_inc(DIAG_STAT_X288);
	return __diag288(func, timeout, action, 0);
}

static unsigned long wdt_status;

#define DIAG_WDOG_BUSY	0

static int wdt_start(struct watchdog_device *dev)
{
	char *ebc_cmd;
	size_t len;
	int ret;
	unsigned int func;

	if (test_and_set_bit(DIAG_WDOG_BUSY, &wdt_status))
		return -EBUSY;

	ret = -ENODEV;

	if (MACHINE_IS_VM) {
		ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
		if (!ebc_cmd) {
			clear_bit(DIAG_WDOG_BUSY, &wdt_status);
			return -ENOMEM;
		}
		len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
		ASCEBC(ebc_cmd, MAX_CMDLEN);
		EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);

		func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
			: WDT_FUNC_INIT;
		ret = __diag288_vm(func, dev->timeout, ebc_cmd, len);
		WARN_ON(ret != 0);
		kfree(ebc_cmd);
	} else {
		ret = __diag288_lpar(WDT_FUNC_INIT,
				     dev->timeout, LPARWDT_RESTART);
	}

	if (ret) {
		pr_err("The watchdog cannot be activated\n");
		clear_bit(DIAG_WDOG_BUSY, &wdt_status);
		return ret;
	}
	return 0;
}

static int wdt_stop(struct watchdog_device *dev)
{
	int ret;

	diag_stat_inc(DIAG_STAT_X288);
	ret = __diag288(WDT_FUNC_CANCEL, 0, 0, 0);

	clear_bit(DIAG_WDOG_BUSY, &wdt_status);

	return ret;
}

static int wdt_ping(struct watchdog_device *dev)
{
	char *ebc_cmd;
	size_t len;
	int ret;
	unsigned int func;

	ret = -ENODEV;

	if (MACHINE_IS_VM) {
		ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
		if (!ebc_cmd)
			return -ENOMEM;
		len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
		ASCEBC(ebc_cmd, MAX_CMDLEN);
		EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);

		/*
		 * It seems to be ok to z/VM to use the init function to
		 * retrigger the watchdog. On LPAR WDT_FUNC_CHANGE must
		 * be used when the watchdog is running.
		 */
		func = conceal_on ? (WDT_FUNC_INIT | WDT_FUNC_CONCEAL)
			: WDT_FUNC_INIT;

		ret = __diag288_vm(func, dev->timeout, ebc_cmd, len);
		WARN_ON(ret != 0);
		kfree(ebc_cmd);
	} else {
		ret = __diag288_lpar(WDT_FUNC_CHANGE, dev->timeout, 0);
	}

	if (ret)
		pr_err("The watchdog timer cannot be started or reset\n");
	return ret;
}

static int wdt_set_timeout(struct watchdog_device * dev, unsigned int new_to)
{
	dev->timeout = new_to;
	return wdt_ping(dev);
}

static const struct watchdog_ops wdt_ops = {
	.owner = THIS_MODULE,
	.start = wdt_start,
	.stop = wdt_stop,
	.ping = wdt_ping,
	.set_timeout = wdt_set_timeout,
};

static const struct watchdog_info wdt_info = {
	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
	.firmware_version = 0,
	.identity = "z Watchdog",
};

static struct watchdog_device wdt_dev = {
	.parent = NULL,
	.info = &wdt_info,
	.ops = &wdt_ops,
	.bootstatus = 0,
	.timeout = WDT_DEFAULT_TIMEOUT,
	.min_timeout = MIN_INTERVAL,
	.max_timeout = MAX_INTERVAL,
};

/*
 * 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.
 */
static int wdt_suspend(void)
{
	if (test_and_set_bit(DIAG_WDOG_BUSY, &wdt_status)) {
		pr_err("Linux cannot be suspended while the watchdog is in use\n");
		return notifier_from_errno(-EBUSY);
	}
	return NOTIFY_DONE;
}

static int wdt_resume(void)
{
	clear_bit(DIAG_WDOG_BUSY, &wdt_status);
	return NOTIFY_DONE;
}

static int wdt_power_event(struct notifier_block *this, unsigned long event,
			   void *ptr)
{
	switch (event) {
	case PM_POST_HIBERNATION:
	case PM_POST_SUSPEND:
		return wdt_resume();
	case PM_HIBERNATION_PREPARE:
	case PM_SUSPEND_PREPARE:
		return wdt_suspend();
	default:
		return NOTIFY_DONE;
	}
}

static struct notifier_block wdt_power_notifier = {
	.notifier_call = wdt_power_event,
};

static int __init diag288_init(void)
{
	int ret;
	char ebc_begin[] = {
		194, 197, 199, 201, 213
	};

	watchdog_set_nowayout(&wdt_dev, nowayout_info);

	if (MACHINE_IS_VM) {
		if (__diag288_vm(WDT_FUNC_INIT, 15,
				 ebc_begin, sizeof(ebc_begin)) != 0) {
			pr_err("The watchdog cannot be initialized\n");
			return -EINVAL;
		}
	} else {
		if (__diag288_lpar(WDT_FUNC_INIT, 30, LPARWDT_RESTART)) {
			pr_err("The watchdog cannot be initialized\n");
			return -EINVAL;
		}
	}

	if (__diag288_lpar(WDT_FUNC_CANCEL, 0, 0)) {
		pr_err("The watchdog cannot be deactivated\n");
		return -EINVAL;
	}

	ret = register_pm_notifier(&wdt_power_notifier);
	if (ret)
		return ret;

	ret = watchdog_register_device(&wdt_dev);
	if (ret)
		unregister_pm_notifier(&wdt_power_notifier);

	return ret;
}

static void __exit diag288_exit(void)
{
	watchdog_unregister_device(&wdt_dev);
	unregister_pm_notifier(&wdt_power_notifier);
}

module_init(diag288_init);
module_exit(diag288_exit);
Commit	Line	Data
09c434b8	1	// SPDX-License-Identifier: GPL-2.0-only
f7a94db4	2	/*
646f919e	3	* Watchdog driver for z/VM and LPAR using the diag 288 interface.
f7a94db4 PH	4	*
	5	* Under z/VM, expiration of the watchdog will send a "system restart" command
	6	* to CP.
	7	*
646f919e PH	8	* The command can be altered using the module parameter "cmd". This is
	9	* not recommended because it's only supported on z/VM but not whith LPAR.
	10	*
	11	* On LPAR, the watchdog will always trigger a system restart. the module
	12	* paramter cmd is meaningless here.
	13	*
f7a94db4 PH	14	*
	15	* Copyright IBM Corp. 2004, 2013
	16	* Author(s): Arnd Bergmann (arndb@de.ibm.com)
	17	* Philipp Hachtmann (phacht@de.ibm.com)
	18	*
	19	*/
	20
	21	#define KMSG_COMPONENT "diag288_wdt"
	22	#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
	23
	24	#include <linux/init.h>
	25	#include <linux/kernel.h>
	26	#include <linux/module.h>
	27	#include <linux/moduleparam.h>
	28	#include <linux/slab.h>
	29	#include <linux/miscdevice.h>
	30	#include <linux/watchdog.h>
	31	#include <linux/suspend.h>
	32	#include <asm/ebcdic.h>
1ec2772e	33	#include <asm/diag.h>
f7a94db4 PH	34	#include <linux/io.h>
	35	#include <linux/uaccess.h>
	36
	37	#define MAX_CMDLEN 240
	38	#define DEFAULT_CMD "SYSTEM RESTART"
	39
	40	#define MIN_INTERVAL 15 /* Minimal time supported by diag88 */
	41	#define MAX_INTERVAL 3600 /* One hour should be enough - pure estimation */
	42
	43	#define WDT_DEFAULT_TIMEOUT 30
	44
	45	/* Function codes - init, change, cancel */
	46	#define WDT_FUNC_INIT 0
	47	#define WDT_FUNC_CHANGE 1
	48	#define WDT_FUNC_CANCEL 2
	49	#define WDT_FUNC_CONCEAL 0x80000000
	50
646f919e PH	51	/* Action codes for LPAR watchdog */
	52	#define LPARWDT_RESTART 0
	53
f7a94db4 PH	54	static char wdt_cmd[MAX_CMDLEN] = DEFAULT_CMD;
	55	static bool conceal_on;
	56	static bool nowayout_info = WATCHDOG_NOWAYOUT;
	57
	58	MODULE_LICENSE("GPL");
	59	MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
	60	MODULE_AUTHOR("Philipp Hachtmann <phacht@de.ibm.com>");
	61
	62	MODULE_DESCRIPTION("System z diag288 Watchdog Timer");
	63
	64	module_param_string(cmd, wdt_cmd, MAX_CMDLEN, 0644);
	65	MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers (z/VM only)");
	66
	67	module_param_named(conceal, conceal_on, bool, 0644);
	68	MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog is active (z/VM only)");
	69
	70	module_param_named(nowayout, nowayout_info, bool, 0444);
	71	MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default = CONFIG_WATCHDOG_NOWAYOUT)");
	72
	73	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
	74	MODULE_ALIAS("vmwatchdog");
	75
	76	static int __diag288(unsigned int func, unsigned int timeout,
	77	unsigned long action, unsigned int len)
	78	{
	79	register unsigned long __func asm("2") = func;
	80	register unsigned long __timeout asm("3") = timeout;
	81	register unsigned long __action asm("4") = action;
	82	register unsigned long __len asm("5") = len;
	83	int err;
	84
	85	err = -EINVAL;
	86	asm volatile(
	87	" diag %1, %3, 0x288\n"
	88	"0: la %0, 0\n"
	89	"1:\n"
	90	EX_TABLE(0b, 1b)
	91	: "+d" (err) : "d"(__func), "d"(__timeout),
	92	"d"(__action), "d"(__len) : "1", "cc");
	93	return err;
	94	}
	95
	96	static int __diag288_vm(unsigned int func, unsigned int timeout,
	97	char *cmd, size_t len)
	98	{
1ec2772e	99	diag_stat_inc(DIAG_STAT_X288);
f7a94db4 PH	100	return __diag288(func, timeout, virt_to_phys(cmd), len);
	101	}
	102
646f919e PH	103	static int __diag288_lpar(unsigned int func, unsigned int timeout,
	104	unsigned long action)
	105	{
1ec2772e	106	diag_stat_inc(DIAG_STAT_X288);
646f919e PH	107	return __diag288(func, timeout, action, 0);
	108	}
	109
e7d162fa GR	110	static unsigned long wdt_status;
	111
	112	#define DIAG_WDOG_BUSY 0
	113
f7a94db4 PH	114	static int wdt_start(struct watchdog_device *dev)
	115	{
	116	char *ebc_cmd;
	117	size_t len;
	118	int ret;
	119	unsigned int func;
	120
e7d162fa GR	121	if (test_and_set_bit(DIAG_WDOG_BUSY, &wdt_status))
	122	return -EBUSY;
	123
f7a94db4 PH	124	ret = -ENODEV;
	125
	126	if (MACHINE_IS_VM) {
	127	ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
e7d162fa GR	128	if (!ebc_cmd) {
e7d162fa GR	129	clear_bit(DIAG_WDOG_BUSY, &wdt_status);
f7a94db4	130	return -ENOMEM;
e7d162fa	131	}
f7a94db4 PH	132	len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
	133	ASCEBC(ebc_cmd, MAX_CMDLEN);
	134	EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
	135
	136	func = conceal_on ? (WDT_FUNC_INIT \| WDT_FUNC_CONCEAL)
	137	: WDT_FUNC_INIT;
	138	ret = __diag288_vm(func, dev->timeout, ebc_cmd, len);
	139	WARN_ON(ret != 0);
	140	kfree(ebc_cmd);
b2527d20	141	} else {
646f919e PH	142	ret = __diag288_lpar(WDT_FUNC_INIT,
	143	dev->timeout, LPARWDT_RESTART);
	144	}
	145
f7a94db4 PH	146	if (ret) {
f7a94db4 PH	147	pr_err("The watchdog cannot be activated\n");
e7d162fa	148	clear_bit(DIAG_WDOG_BUSY, &wdt_status);
f7a94db4 PH	149	return ret;
f7a94db4 PH	150	}
f7a94db4 PH	151	return 0;
	152	}
	153
	154	static int wdt_stop(struct watchdog_device *dev)
	155	{
	156	int ret;
	157
1ec2772e	158	diag_stat_inc(DIAG_STAT_X288);
f7a94db4	159	ret = __diag288(WDT_FUNC_CANCEL, 0, 0, 0);
e7d162fa GR	160
	161	clear_bit(DIAG_WDOG_BUSY, &wdt_status);
	162
f7a94db4 PH	163	return ret;
	164	}
	165
	166	static int wdt_ping(struct watchdog_device *dev)
	167	{
	168	char *ebc_cmd;
	169	size_t len;
	170	int ret;
	171	unsigned int func;
	172
	173	ret = -ENODEV;
	174
	175	if (MACHINE_IS_VM) {
	176	ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
	177	if (!ebc_cmd)
	178	return -ENOMEM;
	179	len = strlcpy(ebc_cmd, wdt_cmd, MAX_CMDLEN);
	180	ASCEBC(ebc_cmd, MAX_CMDLEN);
	181	EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
	182
	183	/*
	184	* It seems to be ok to z/VM to use the init function to
646f919e PH	185	* retrigger the watchdog. On LPAR WDT_FUNC_CHANGE must
646f919e PH	186	* be used when the watchdog is running.
f7a94db4 PH	187	*/
	188	func = conceal_on ? (WDT_FUNC_INIT \| WDT_FUNC_CONCEAL)
	189	: WDT_FUNC_INIT;
	190
	191	ret = __diag288_vm(func, dev->timeout, ebc_cmd, len);
	192	WARN_ON(ret != 0);
	193	kfree(ebc_cmd);
b2527d20	194	} else {
646f919e	195	ret = __diag288_lpar(WDT_FUNC_CHANGE, dev->timeout, 0);
b2527d20	196	}
646f919e	197
f7a94db4 PH	198	if (ret)
	199	pr_err("The watchdog timer cannot be started or reset\n");
	200	return ret;
	201	}
	202
	203	static int wdt_set_timeout(struct watchdog_device * dev, unsigned int new_to)
	204	{
	205	dev->timeout = new_to;
	206	return wdt_ping(dev);
	207	}
	208
b893e344	209	static const struct watchdog_ops wdt_ops = {
f7a94db4 PH	210	.owner = THIS_MODULE,
	211	.start = wdt_start,
	212	.stop = wdt_stop,
	213	.ping = wdt_ping,
	214	.set_timeout = wdt_set_timeout,
	215	};
	216
323edb2e	217	static const struct watchdog_info wdt_info = {
9ec6cb80	218	.options = WDIOF_SETTIMEOUT \| WDIOF_KEEPALIVEPING \| WDIOF_MAGICCLOSE,
f7a94db4 PH	219	.firmware_version = 0,
	220	.identity = "z Watchdog",
	221	};
	222
	223	static struct watchdog_device wdt_dev = {
	224	.parent = NULL,
	225	.info = &wdt_info,
	226	.ops = &wdt_ops,
	227	.bootstatus = 0,
	228	.timeout = WDT_DEFAULT_TIMEOUT,
	229	.min_timeout = MIN_INTERVAL,
	230	.max_timeout = MAX_INTERVAL,
	231	};
	232
	233	/*
	234	* It makes no sense to go into suspend while the watchdog is running.
	235	* Depending on the memory size, the watchdog might trigger, while we
	236	* are still saving the memory.
f7a94db4 PH	237	*/
	238	static int wdt_suspend(void)
	239	{
e7d162fa	240	if (test_and_set_bit(DIAG_WDOG_BUSY, &wdt_status)) {
f7a94db4 PH	241	pr_err("Linux cannot be suspended while the watchdog is in use\n");
	242	return notifier_from_errno(-EBUSY);
	243	}
	244	return NOTIFY_DONE;
	245	}
	246
	247	static int wdt_resume(void)
	248	{
e7d162fa	249	clear_bit(DIAG_WDOG_BUSY, &wdt_status);
f7a94db4 PH	250	return NOTIFY_DONE;
	251	}
	252
	253	static int wdt_power_event(struct notifier_block *this, unsigned long event,
	254	void *ptr)
	255	{
	256	switch (event) {
	257	case PM_POST_HIBERNATION:
	258	case PM_POST_SUSPEND:
	259	return wdt_resume();
	260	case PM_HIBERNATION_PREPARE:
	261	case PM_SUSPEND_PREPARE:
	262	return wdt_suspend();
	263	default:
	264	return NOTIFY_DONE;
	265	}
	266	}
	267
	268	static struct notifier_block wdt_power_notifier = {
	269	.notifier_call = wdt_power_event,
	270	};
	271
	272	static int __init diag288_init(void)
	273	{
	274	int ret;
	275	char ebc_begin[] = {
	276	194, 197, 199, 201, 213
	277	};
	278
	279	watchdog_set_nowayout(&wdt_dev, nowayout_info);
	280
	281	if (MACHINE_IS_VM) {
f7a94db4 PH	282	if (__diag288_vm(WDT_FUNC_INIT, 15,
	283	ebc_begin, sizeof(ebc_begin)) != 0) {
	284	pr_err("The watchdog cannot be initialized\n");
	285	return -EINVAL;
	286	}
b2527d20	287	} else {
646f919e PH	288	if (__diag288_lpar(WDT_FUNC_INIT, 30, LPARWDT_RESTART)) {
	289	pr_err("The watchdog cannot be initialized\n");
	290	return -EINVAL;
	291	}
f7a94db4 PH	292	}
f7a94db4 PH	293
646f919e	294	if (__diag288_lpar(WDT_FUNC_CANCEL, 0, 0)) {
f7a94db4 PH	295	pr_err("The watchdog cannot be deactivated\n");
	296	return -EINVAL;
	297	}
	298
	299	ret = register_pm_notifier(&wdt_power_notifier);
	300	if (ret)
	301	return ret;
	302
	303	ret = watchdog_register_device(&wdt_dev);
	304	if (ret)
	305	unregister_pm_notifier(&wdt_power_notifier);
	306
	307	return ret;
	308	}
	309
	310	static void __exit diag288_exit(void)
	311	{
	312	watchdog_unregister_device(&wdt_dev);
	313	unregister_pm_notifier(&wdt_power_notifier);
	314	}
	315
	316	module_init(diag288_init);
	317	module_exit(diag288_exit);