summaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/xen_wdt.c
blob: b343f421dc72c597e818315767ccb65d908639a3 (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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *	Xen Watchdog Driver
 *
 *	(c) Copyright 2010 Novell, Inc.
 */

#define DRV_NAME	"xen_wdt"

#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/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.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 struct sched_watchdog wdt;
static time64_t wdt_expires;

#define WATCHDOG_TIMEOUT 60 /* in seconds */
static unsigned int 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 time64_t set_timeout(struct watchdog_device *wdd)
{
	wdt.timeout = wdd->timeout;
	return ktime_get_seconds() + wdd->timeout;
}

static int xen_wdt_start(struct watchdog_device *wdd)
{
	time64_t expires;
	int err;

	expires = set_timeout(wdd);
	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);

	return err;
}

static int xen_wdt_stop(struct watchdog_device *wdd)
{
	int err = 0;

	wdt.timeout = 0;
	if (wdt.id)
		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
	if (!err)
		wdt.id = 0;

	return err;
}

static int xen_wdt_kick(struct watchdog_device *wdd)
{
	time64_t expires;
	int err;

	expires = set_timeout(wdd);
	if (wdt.id)
		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
	else
		err = -ENXIO;
	if (!err)
		wdt_expires = expires;

	return err;
}

static unsigned int xen_wdt_get_timeleft(struct watchdog_device *wdd)
{
	return wdt_expires - ktime_get_seconds();
}

static struct watchdog_info xen_wdt_info = {
	.identity = DRV_NAME,
	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
};

static const struct watchdog_ops xen_wdt_ops = {
	.owner = THIS_MODULE,
	.start = xen_wdt_start,
	.stop = xen_wdt_stop,
	.ping = xen_wdt_kick,
	.get_timeleft = xen_wdt_get_timeleft,
};

static struct watchdog_device xen_wdt_dev = {
	.info = &xen_wdt_info,
	.ops = &xen_wdt_ops,
	.timeout = WATCHDOG_TIMEOUT,
};

static int xen_wdt_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct sched_watchdog wd = { .id = ~0 };
	int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);

	if (ret == -ENOSYS) {
		dev_err(dev, "watchdog not supported by hypervisor\n");
		return -ENODEV;
	}

	if (ret != -EINVAL) {
		dev_err(dev, "unexpected hypervisor error (%d)\n", ret);
		return -ENODEV;
	}

	watchdog_init_timeout(&xen_wdt_dev, timeout, NULL);
	watchdog_set_nowayout(&xen_wdt_dev, nowayout);
	watchdog_stop_on_reboot(&xen_wdt_dev);
	watchdog_stop_on_unregister(&xen_wdt_dev);

	ret = devm_watchdog_register_device(dev, &xen_wdt_dev);
	if (ret)
		return ret;

	dev_info(dev, "initialized (timeout=%ds, nowayout=%d)\n",
		 xen_wdt_dev.timeout, nowayout);

	return 0;
}

static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
{
	typeof(wdt.id) id = wdt.id;
	int rc = xen_wdt_stop(&xen_wdt_dev);

	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(&xen_wdt_dev);
}

static struct platform_driver xen_wdt_driver = {
	.probe          = xen_wdt_probe,
	.suspend        = xen_wdt_suspend,
	.resume         = xen_wdt_resume,
	.driver         = {
		.name   = DRV_NAME,
	},
};

static int __init xen_wdt_init_module(void)
{
	int err;

	if (!xen_domain())
		return -ENODEV;

	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);
}

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_LICENSE("GPL");
OpenPOWER on IntegriCloud