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12#define DRV_NAME "xen_wdt"
13
14#include <linux/bug.h>
15#include <linux/errno.h>
16#include <linux/fs.h>
17#include <linux/hrtimer.h>
18#include <linux/kernel.h>
19#include <linux/ktime.h>
20#include <linux/init.h>
21#include <linux/module.h>
22#include <linux/moduleparam.h>
23#include <linux/platform_device.h>
24#include <linux/watchdog.h>
25#include <xen/xen.h>
26#include <asm/xen/hypercall.h>
27#include <xen/interface/sched.h>
28
29static struct platform_device *platform_device;
30static struct sched_watchdog wdt;
31static time64_t wdt_expires;
32
33#define WATCHDOG_TIMEOUT 60
34static unsigned int timeout;
35module_param(timeout, uint, S_IRUGO);
36MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
37 "(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
38
39static bool nowayout = WATCHDOG_NOWAYOUT;
40module_param(nowayout, bool, S_IRUGO);
41MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
42 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
43
44static inline time64_t set_timeout(struct watchdog_device *wdd)
45{
46 wdt.timeout = wdd->timeout;
47 return ktime_get_seconds() + wdd->timeout;
48}
49
50static int xen_wdt_start(struct watchdog_device *wdd)
51{
52 time64_t expires;
53 int err;
54
55 expires = set_timeout(wdd);
56 if (!wdt.id)
57 err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
58 else
59 err = -EBUSY;
60 if (err > 0) {
61 wdt.id = err;
62 wdt_expires = expires;
63 err = 0;
64 } else
65 BUG_ON(!err);
66
67 return err;
68}
69
70static int xen_wdt_stop(struct watchdog_device *wdd)
71{
72 int err = 0;
73
74 wdt.timeout = 0;
75 if (wdt.id)
76 err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
77 if (!err)
78 wdt.id = 0;
79
80 return err;
81}
82
83static int xen_wdt_kick(struct watchdog_device *wdd)
84{
85 time64_t expires;
86 int err;
87
88 expires = set_timeout(wdd);
89 if (wdt.id)
90 err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
91 else
92 err = -ENXIO;
93 if (!err)
94 wdt_expires = expires;
95
96 return err;
97}
98
99static unsigned int xen_wdt_get_timeleft(struct watchdog_device *wdd)
100{
101 return wdt_expires - ktime_get_seconds();
102}
103
104static struct watchdog_info xen_wdt_info = {
105 .identity = DRV_NAME,
106 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
107};
108
109static const struct watchdog_ops xen_wdt_ops = {
110 .owner = THIS_MODULE,
111 .start = xen_wdt_start,
112 .stop = xen_wdt_stop,
113 .ping = xen_wdt_kick,
114 .get_timeleft = xen_wdt_get_timeleft,
115};
116
117static struct watchdog_device xen_wdt_dev = {
118 .info = &xen_wdt_info,
119 .ops = &xen_wdt_ops,
120 .timeout = WATCHDOG_TIMEOUT,
121};
122
123static int xen_wdt_probe(struct platform_device *pdev)
124{
125 struct sched_watchdog wd = { .id = ~0 };
126 int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
127
128 if (ret == -ENOSYS) {
129 dev_err(&pdev->dev, "watchdog not supported by hypervisor\n");
130 return -ENODEV;
131 }
132
133 if (ret != -EINVAL) {
134 dev_err(&pdev->dev, "unexpected hypervisor error (%d)\n", ret);
135 return -ENODEV;
136 }
137
138 if (watchdog_init_timeout(&xen_wdt_dev, timeout, NULL))
139 dev_info(&pdev->dev, "timeout value invalid, using %d\n",
140 xen_wdt_dev.timeout);
141 watchdog_set_nowayout(&xen_wdt_dev, nowayout);
142 watchdog_stop_on_reboot(&xen_wdt_dev);
143 watchdog_stop_on_unregister(&xen_wdt_dev);
144
145 ret = devm_watchdog_register_device(&pdev->dev, &xen_wdt_dev);
146 if (ret) {
147 dev_err(&pdev->dev, "cannot register watchdog device (%d)\n",
148 ret);
149 return ret;
150 }
151
152 dev_info(&pdev->dev, "initialized (timeout=%ds, nowayout=%d)\n",
153 xen_wdt_dev.timeout, nowayout);
154
155 return 0;
156}
157
158static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
159{
160 typeof(wdt.id) id = wdt.id;
161 int rc = xen_wdt_stop(&xen_wdt_dev);
162
163 wdt.id = id;
164 return rc;
165}
166
167static int xen_wdt_resume(struct platform_device *dev)
168{
169 if (!wdt.id)
170 return 0;
171 wdt.id = 0;
172 return xen_wdt_start(&xen_wdt_dev);
173}
174
175static struct platform_driver xen_wdt_driver = {
176 .probe = xen_wdt_probe,
177 .suspend = xen_wdt_suspend,
178 .resume = xen_wdt_resume,
179 .driver = {
180 .name = DRV_NAME,
181 },
182};
183
184static int __init xen_wdt_init_module(void)
185{
186 int err;
187
188 if (!xen_domain())
189 return -ENODEV;
190
191 err = platform_driver_register(&xen_wdt_driver);
192 if (err)
193 return err;
194
195 platform_device = platform_device_register_simple(DRV_NAME,
196 -1, NULL, 0);
197 if (IS_ERR(platform_device)) {
198 err = PTR_ERR(platform_device);
199 platform_driver_unregister(&xen_wdt_driver);
200 }
201
202 return err;
203}
204
205static void __exit xen_wdt_cleanup_module(void)
206{
207 platform_device_unregister(platform_device);
208 platform_driver_unregister(&xen_wdt_driver);
209}
210
211module_init(xen_wdt_init_module);
212module_exit(xen_wdt_cleanup_module);
213
214MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>");
215MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
216MODULE_LICENSE("GPL");
217
