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066d6c7f JB |
1 | /* |
2 | * Xen Watchdog Driver | |
3 | * | |
4 | * (c) Copyright 2010 Novell, Inc. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | */ | |
11 | ||
27c766aa JP |
12 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
13 | ||
066d6c7f JB |
14 | #define DRV_NAME "wdt" |
15 | #define DRV_VERSION "0.01" | |
066d6c7f JB |
16 | |
17 | #include <linux/bug.h> | |
18 | #include <linux/errno.h> | |
19 | #include <linux/fs.h> | |
20 | #include <linux/hrtimer.h> | |
21 | #include <linux/kernel.h> | |
22 | #include <linux/ktime.h> | |
23 | #include <linux/init.h> | |
24 | #include <linux/miscdevice.h> | |
25 | #include <linux/module.h> | |
26 | #include <linux/moduleparam.h> | |
27 | #include <linux/platform_device.h> | |
28 | #include <linux/spinlock.h> | |
29 | #include <linux/uaccess.h> | |
30 | #include <linux/watchdog.h> | |
31 | #include <xen/xen.h> | |
32 | #include <asm/xen/hypercall.h> | |
33 | #include <xen/interface/sched.h> | |
34 | ||
35 | static struct platform_device *platform_device; | |
36 | static DEFINE_SPINLOCK(wdt_lock); | |
37 | static struct sched_watchdog wdt; | |
38 | static __kernel_time_t wdt_expires; | |
39 | static bool is_active, expect_release; | |
40 | ||
41 | #define WATCHDOG_TIMEOUT 60 /* in seconds */ | |
42 | static unsigned int timeout = WATCHDOG_TIMEOUT; | |
43 | module_param(timeout, uint, S_IRUGO); | |
44 | MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds " | |
45 | "(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); | |
46 | ||
47 | static bool nowayout = WATCHDOG_NOWAYOUT; | |
48 | module_param(nowayout, bool, S_IRUGO); | |
49 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " | |
50 | "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); | |
51 | ||
52 | static inline __kernel_time_t set_timeout(void) | |
53 | { | |
54 | wdt.timeout = timeout; | |
55 | return ktime_to_timespec(ktime_get()).tv_sec + timeout; | |
56 | } | |
57 | ||
58 | static int xen_wdt_start(void) | |
59 | { | |
60 | __kernel_time_t expires; | |
61 | int err; | |
62 | ||
63 | spin_lock(&wdt_lock); | |
64 | ||
65 | expires = set_timeout(); | |
66 | if (!wdt.id) | |
67 | err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt); | |
68 | else | |
69 | err = -EBUSY; | |
70 | if (err > 0) { | |
71 | wdt.id = err; | |
72 | wdt_expires = expires; | |
73 | err = 0; | |
74 | } else | |
75 | BUG_ON(!err); | |
76 | ||
77 | spin_unlock(&wdt_lock); | |
78 | ||
79 | return err; | |
80 | } | |
81 | ||
82 | static int xen_wdt_stop(void) | |
83 | { | |
84 | int err = 0; | |
85 | ||
86 | spin_lock(&wdt_lock); | |
87 | ||
88 | wdt.timeout = 0; | |
89 | if (wdt.id) | |
90 | err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt); | |
91 | if (!err) | |
92 | wdt.id = 0; | |
93 | ||
94 | spin_unlock(&wdt_lock); | |
95 | ||
96 | return err; | |
97 | } | |
98 | ||
99 | static int xen_wdt_kick(void) | |
100 | { | |
101 | __kernel_time_t expires; | |
102 | int err; | |
103 | ||
104 | spin_lock(&wdt_lock); | |
105 | ||
106 | expires = set_timeout(); | |
107 | if (wdt.id) | |
108 | err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt); | |
109 | else | |
110 | err = -ENXIO; | |
111 | if (!err) | |
112 | wdt_expires = expires; | |
113 | ||
114 | spin_unlock(&wdt_lock); | |
115 | ||
116 | return err; | |
117 | } | |
118 | ||
119 | static int xen_wdt_open(struct inode *inode, struct file *file) | |
120 | { | |
121 | int err; | |
122 | ||
123 | /* /dev/watchdog can only be opened once */ | |
124 | if (xchg(&is_active, true)) | |
125 | return -EBUSY; | |
126 | ||
127 | err = xen_wdt_start(); | |
128 | if (err == -EBUSY) | |
129 | err = xen_wdt_kick(); | |
130 | return err ?: nonseekable_open(inode, file); | |
131 | } | |
132 | ||
133 | static int xen_wdt_release(struct inode *inode, struct file *file) | |
134 | { | |
135 | if (expect_release) | |
136 | xen_wdt_stop(); | |
137 | else { | |
27c766aa | 138 | pr_crit("unexpected close, not stopping watchdog!\n"); |
066d6c7f JB |
139 | xen_wdt_kick(); |
140 | } | |
141 | is_active = false; | |
142 | expect_release = false; | |
143 | return 0; | |
144 | } | |
145 | ||
146 | static ssize_t xen_wdt_write(struct file *file, const char __user *data, | |
147 | size_t len, loff_t *ppos) | |
148 | { | |
149 | /* See if we got the magic character 'V' and reload the timer */ | |
150 | if (len) { | |
151 | if (!nowayout) { | |
152 | size_t i; | |
153 | ||
154 | /* in case it was set long ago */ | |
155 | expect_release = false; | |
156 | ||
157 | /* scan to see whether or not we got the magic | |
158 | character */ | |
159 | for (i = 0; i != len; i++) { | |
160 | char c; | |
161 | if (get_user(c, data + i)) | |
162 | return -EFAULT; | |
163 | if (c == 'V') | |
164 | expect_release = true; | |
165 | } | |
166 | } | |
167 | ||
168 | /* someone wrote to us, we should reload the timer */ | |
169 | xen_wdt_kick(); | |
170 | } | |
171 | return len; | |
172 | } | |
173 | ||
174 | static long xen_wdt_ioctl(struct file *file, unsigned int cmd, | |
175 | unsigned long arg) | |
176 | { | |
177 | int new_options, retval = -EINVAL; | |
178 | int new_timeout; | |
179 | int __user *argp = (void __user *)arg; | |
180 | static const struct watchdog_info ident = { | |
181 | .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, | |
182 | .firmware_version = 0, | |
183 | .identity = DRV_NAME, | |
184 | }; | |
185 | ||
186 | switch (cmd) { | |
187 | case WDIOC_GETSUPPORT: | |
188 | return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; | |
189 | ||
190 | case WDIOC_GETSTATUS: | |
191 | case WDIOC_GETBOOTSTATUS: | |
192 | return put_user(0, argp); | |
193 | ||
194 | case WDIOC_SETOPTIONS: | |
195 | if (get_user(new_options, argp)) | |
196 | return -EFAULT; | |
197 | ||
198 | if (new_options & WDIOS_DISABLECARD) | |
199 | retval = xen_wdt_stop(); | |
200 | if (new_options & WDIOS_ENABLECARD) { | |
201 | retval = xen_wdt_start(); | |
202 | if (retval == -EBUSY) | |
203 | retval = xen_wdt_kick(); | |
204 | } | |
205 | return retval; | |
206 | ||
207 | case WDIOC_KEEPALIVE: | |
208 | xen_wdt_kick(); | |
209 | return 0; | |
210 | ||
211 | case WDIOC_SETTIMEOUT: | |
212 | if (get_user(new_timeout, argp)) | |
213 | return -EFAULT; | |
214 | if (!new_timeout) | |
215 | return -EINVAL; | |
216 | timeout = new_timeout; | |
217 | xen_wdt_kick(); | |
218 | /* fall through */ | |
219 | case WDIOC_GETTIMEOUT: | |
220 | return put_user(timeout, argp); | |
221 | ||
222 | case WDIOC_GETTIMELEFT: | |
223 | retval = wdt_expires - ktime_to_timespec(ktime_get()).tv_sec; | |
224 | return put_user(retval, argp); | |
225 | } | |
226 | ||
227 | return -ENOTTY; | |
228 | } | |
229 | ||
230 | static const struct file_operations xen_wdt_fops = { | |
231 | .owner = THIS_MODULE, | |
232 | .llseek = no_llseek, | |
233 | .write = xen_wdt_write, | |
234 | .unlocked_ioctl = xen_wdt_ioctl, | |
235 | .open = xen_wdt_open, | |
236 | .release = xen_wdt_release, | |
237 | }; | |
238 | ||
239 | static struct miscdevice xen_wdt_miscdev = { | |
240 | .minor = WATCHDOG_MINOR, | |
241 | .name = "watchdog", | |
242 | .fops = &xen_wdt_fops, | |
243 | }; | |
244 | ||
245 | static int __devinit xen_wdt_probe(struct platform_device *dev) | |
246 | { | |
247 | struct sched_watchdog wd = { .id = ~0 }; | |
248 | int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd); | |
249 | ||
250 | switch (ret) { | |
251 | case -EINVAL: | |
252 | if (!timeout) { | |
253 | timeout = WATCHDOG_TIMEOUT; | |
27c766aa | 254 | pr_info("timeout value invalid, using %d\n", timeout); |
066d6c7f JB |
255 | } |
256 | ||
257 | ret = misc_register(&xen_wdt_miscdev); | |
258 | if (ret) { | |
27c766aa | 259 | pr_err("cannot register miscdev on minor=%d (%d)\n", |
066d6c7f JB |
260 | WATCHDOG_MINOR, ret); |
261 | break; | |
262 | } | |
263 | ||
27c766aa JP |
264 | pr_info("initialized (timeout=%ds, nowayout=%d)\n", |
265 | timeout, nowayout); | |
066d6c7f JB |
266 | break; |
267 | ||
268 | case -ENOSYS: | |
27c766aa | 269 | pr_info("not supported\n"); |
066d6c7f JB |
270 | ret = -ENODEV; |
271 | break; | |
272 | ||
273 | default: | |
27c766aa | 274 | pr_info("bogus return value %d\n", ret); |
066d6c7f JB |
275 | break; |
276 | } | |
277 | ||
278 | return ret; | |
279 | } | |
280 | ||
281 | static int __devexit xen_wdt_remove(struct platform_device *dev) | |
282 | { | |
283 | /* Stop the timer before we leave */ | |
284 | if (!nowayout) | |
285 | xen_wdt_stop(); | |
286 | ||
287 | misc_deregister(&xen_wdt_miscdev); | |
288 | ||
289 | return 0; | |
290 | } | |
291 | ||
292 | static void xen_wdt_shutdown(struct platform_device *dev) | |
293 | { | |
294 | xen_wdt_stop(); | |
295 | } | |
296 | ||
297 | static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state) | |
298 | { | |
299 | return xen_wdt_stop(); | |
300 | } | |
301 | ||
302 | static int xen_wdt_resume(struct platform_device *dev) | |
303 | { | |
304 | return xen_wdt_start(); | |
305 | } | |
306 | ||
307 | static struct platform_driver xen_wdt_driver = { | |
308 | .probe = xen_wdt_probe, | |
309 | .remove = __devexit_p(xen_wdt_remove), | |
310 | .shutdown = xen_wdt_shutdown, | |
311 | .suspend = xen_wdt_suspend, | |
312 | .resume = xen_wdt_resume, | |
313 | .driver = { | |
314 | .owner = THIS_MODULE, | |
315 | .name = DRV_NAME, | |
316 | }, | |
317 | }; | |
318 | ||
319 | static int __init xen_wdt_init_module(void) | |
320 | { | |
321 | int err; | |
322 | ||
323 | if (!xen_domain()) | |
324 | return -ENODEV; | |
325 | ||
27c766aa | 326 | pr_info("Xen WatchDog Timer Driver v%s\n", DRV_VERSION); |
066d6c7f JB |
327 | |
328 | err = platform_driver_register(&xen_wdt_driver); | |
329 | if (err) | |
330 | return err; | |
331 | ||
332 | platform_device = platform_device_register_simple(DRV_NAME, | |
333 | -1, NULL, 0); | |
334 | if (IS_ERR(platform_device)) { | |
335 | err = PTR_ERR(platform_device); | |
336 | platform_driver_unregister(&xen_wdt_driver); | |
337 | } | |
338 | ||
339 | return err; | |
340 | } | |
341 | ||
342 | static void __exit xen_wdt_cleanup_module(void) | |
343 | { | |
344 | platform_device_unregister(platform_device); | |
345 | platform_driver_unregister(&xen_wdt_driver); | |
27c766aa | 346 | pr_info("module unloaded\n"); |
066d6c7f JB |
347 | } |
348 | ||
349 | module_init(xen_wdt_init_module); | |
350 | module_exit(xen_wdt_cleanup_module); | |
351 | ||
352 | MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>"); | |
353 | MODULE_DESCRIPTION("Xen WatchDog Timer Driver"); | |
354 | MODULE_VERSION(DRV_VERSION); | |
355 | MODULE_LICENSE("GPL"); | |
356 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |