aboutsummaryrefslogtreecommitdiff
path: root/drivers/watchdog/diag288_wdt.c
blob: 3db9d0e0673de32546e227f97b1a7ed99679e8dd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
/*
 * 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 int wdt_start(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);

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

static 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.
 * We reuse the open flag to ensure that suspend and watchdog open are
 * exclusive operations
 */
static int wdt_suspend(void)
{
	if (test_and_set_bit(WDOG_DEV_OPEN, &wdt_dev.status)) {
		pr_err("Linux cannot be suspended while the watchdog is in use\n");
		return notifier_from_errno(-EBUSY);
	}
	if (test_bit(WDOG_ACTIVE, &wdt_dev.status)) {
		clear_bit(WDOG_DEV_OPEN, &wdt_dev.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(WDOG_DEV_OPEN, &wdt_dev.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);