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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
25static struct platform_device *platform_device;
26static struct sched_watchdog wdt;
27static time64_t wdt_expires;
28
29#define WATCHDOG_TIMEOUT 60
30static unsigned int timeout;
31module_param(timeout, uint, S_IRUGO);
32MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
33 "(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
34
35static bool nowayout = WATCHDOG_NOWAYOUT;
36module_param(nowayout, bool, S_IRUGO);
37MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
38 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
39
40static inline time64_t set_timeout(struct watchdog_device *wdd)
41{
42 wdt.timeout = wdd->timeout;
43 return ktime_get_seconds() + wdd->timeout;
44}
45
46static 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
66static 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
79static 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
95static unsigned int xen_wdt_get_timeleft(struct watchdog_device *wdd)
96{
97 return wdt_expires - ktime_get_seconds();
98}
99
100static struct watchdog_info xen_wdt_info = {
101 .identity = DRV_NAME,
102 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
103};
104
105static 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
113static struct watchdog_device xen_wdt_dev = {
114 .info = &xen_wdt_info,
115 .ops = &xen_wdt_ops,
116 .timeout = WATCHDOG_TIMEOUT,
117};
118
119static 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
150static 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
159static 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
167static 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
176static 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
197static void __exit xen_wdt_cleanup_module(void)
198{
199 platform_device_unregister(platform_device);
200 platform_driver_unregister(&xen_wdt_driver);
201}
202
203module_init(xen_wdt_init_module);
204module_exit(xen_wdt_cleanup_module);
205
206MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>");
207MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
208MODULE_LICENSE("GPL");
209
