xref: /openbmc/linux/drivers/watchdog/xen_wdt.c (revision 55fd7e02)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *	Xen Watchdog Driver
4  *
5  *	(c) Copyright 2010 Novell, Inc.
6  */
7 
8 #define DRV_NAME	"xen_wdt"
9 
10 #include <linux/bug.h>
11 #include <linux/errno.h>
12 #include <linux/fs.h>
13 #include <linux/hrtimer.h>
14 #include <linux/kernel.h>
15 #include <linux/ktime.h>
16 #include <linux/init.h>
17 #include <linux/module.h>
18 #include <linux/moduleparam.h>
19 #include <linux/platform_device.h>
20 #include <linux/watchdog.h>
21 #include <xen/xen.h>
22 #include <asm/xen/hypercall.h>
23 #include <xen/interface/sched.h>
24 
25 static struct platform_device *platform_device;
26 static struct sched_watchdog wdt;
27 static time64_t wdt_expires;
28 
29 #define WATCHDOG_TIMEOUT 60 /* in seconds */
30 static unsigned int timeout;
31 module_param(timeout, uint, S_IRUGO);
32 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
33 	"(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
34 
35 static bool nowayout = WATCHDOG_NOWAYOUT;
36 module_param(nowayout, bool, S_IRUGO);
37 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
38 	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
39 
40 static inline time64_t set_timeout(struct watchdog_device *wdd)
41 {
42 	wdt.timeout = wdd->timeout;
43 	return ktime_get_seconds() + wdd->timeout;
44 }
45 
46 static int xen_wdt_start(struct watchdog_device *wdd)
47 {
48 	time64_t expires;
49 	int err;
50 
51 	expires = set_timeout(wdd);
52 	if (!wdt.id)
53 		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
54 	else
55 		err = -EBUSY;
56 	if (err > 0) {
57 		wdt.id = err;
58 		wdt_expires = expires;
59 		err = 0;
60 	} else
61 		BUG_ON(!err);
62 
63 	return err;
64 }
65 
66 static int xen_wdt_stop(struct watchdog_device *wdd)
67 {
68 	int err = 0;
69 
70 	wdt.timeout = 0;
71 	if (wdt.id)
72 		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
73 	if (!err)
74 		wdt.id = 0;
75 
76 	return err;
77 }
78 
79 static int xen_wdt_kick(struct watchdog_device *wdd)
80 {
81 	time64_t expires;
82 	int err;
83 
84 	expires = set_timeout(wdd);
85 	if (wdt.id)
86 		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
87 	else
88 		err = -ENXIO;
89 	if (!err)
90 		wdt_expires = expires;
91 
92 	return err;
93 }
94 
95 static unsigned int xen_wdt_get_timeleft(struct watchdog_device *wdd)
96 {
97 	return wdt_expires - ktime_get_seconds();
98 }
99 
100 static struct watchdog_info xen_wdt_info = {
101 	.identity = DRV_NAME,
102 	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
103 };
104 
105 static const struct watchdog_ops xen_wdt_ops = {
106 	.owner = THIS_MODULE,
107 	.start = xen_wdt_start,
108 	.stop = xen_wdt_stop,
109 	.ping = xen_wdt_kick,
110 	.get_timeleft = xen_wdt_get_timeleft,
111 };
112 
113 static struct watchdog_device xen_wdt_dev = {
114 	.info = &xen_wdt_info,
115 	.ops = &xen_wdt_ops,
116 	.timeout = WATCHDOG_TIMEOUT,
117 };
118 
119 static int xen_wdt_probe(struct platform_device *pdev)
120 {
121 	struct device *dev = &pdev->dev;
122 	struct sched_watchdog wd = { .id = ~0 };
123 	int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
124 
125 	if (ret == -ENOSYS) {
126 		dev_err(dev, "watchdog not supported by hypervisor\n");
127 		return -ENODEV;
128 	}
129 
130 	if (ret != -EINVAL) {
131 		dev_err(dev, "unexpected hypervisor error (%d)\n", ret);
132 		return -ENODEV;
133 	}
134 
135 	watchdog_init_timeout(&xen_wdt_dev, timeout, NULL);
136 	watchdog_set_nowayout(&xen_wdt_dev, nowayout);
137 	watchdog_stop_on_reboot(&xen_wdt_dev);
138 	watchdog_stop_on_unregister(&xen_wdt_dev);
139 
140 	ret = devm_watchdog_register_device(dev, &xen_wdt_dev);
141 	if (ret)
142 		return ret;
143 
144 	dev_info(dev, "initialized (timeout=%ds, nowayout=%d)\n",
145 		 xen_wdt_dev.timeout, nowayout);
146 
147 	return 0;
148 }
149 
150 static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
151 {
152 	typeof(wdt.id) id = wdt.id;
153 	int rc = xen_wdt_stop(&xen_wdt_dev);
154 
155 	wdt.id = id;
156 	return rc;
157 }
158 
159 static int xen_wdt_resume(struct platform_device *dev)
160 {
161 	if (!wdt.id)
162 		return 0;
163 	wdt.id = 0;
164 	return xen_wdt_start(&xen_wdt_dev);
165 }
166 
167 static struct platform_driver xen_wdt_driver = {
168 	.probe          = xen_wdt_probe,
169 	.suspend        = xen_wdt_suspend,
170 	.resume         = xen_wdt_resume,
171 	.driver         = {
172 		.name   = DRV_NAME,
173 	},
174 };
175 
176 static int __init xen_wdt_init_module(void)
177 {
178 	int err;
179 
180 	if (!xen_domain())
181 		return -ENODEV;
182 
183 	err = platform_driver_register(&xen_wdt_driver);
184 	if (err)
185 		return err;
186 
187 	platform_device = platform_device_register_simple(DRV_NAME,
188 								  -1, NULL, 0);
189 	if (IS_ERR(platform_device)) {
190 		err = PTR_ERR(platform_device);
191 		platform_driver_unregister(&xen_wdt_driver);
192 	}
193 
194 	return err;
195 }
196 
197 static void __exit xen_wdt_cleanup_module(void)
198 {
199 	platform_device_unregister(platform_device);
200 	platform_driver_unregister(&xen_wdt_driver);
201 }
202 
203 module_init(xen_wdt_init_module);
204 module_exit(xen_wdt_cleanup_module);
205 
206 MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>");
207 MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
208 MODULE_LICENSE("GPL");
209