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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 | { | |
38c484fa JB |
135 | int err = 0; |
136 | ||
066d6c7f | 137 | if (expect_release) |
38c484fa | 138 | err = xen_wdt_stop(); |
066d6c7f | 139 | else { |
27c766aa | 140 | pr_crit("unexpected close, not stopping watchdog!\n"); |
066d6c7f JB |
141 | xen_wdt_kick(); |
142 | } | |
38c484fa | 143 | is_active = err; |
066d6c7f | 144 | expect_release = false; |
38c484fa | 145 | return err; |
066d6c7f JB |
146 | } |
147 | ||
148 | static ssize_t xen_wdt_write(struct file *file, const char __user *data, | |
149 | size_t len, loff_t *ppos) | |
150 | { | |
151 | /* See if we got the magic character 'V' and reload the timer */ | |
152 | if (len) { | |
153 | if (!nowayout) { | |
154 | size_t i; | |
155 | ||
156 | /* in case it was set long ago */ | |
157 | expect_release = false; | |
158 | ||
159 | /* scan to see whether or not we got the magic | |
160 | character */ | |
161 | for (i = 0; i != len; i++) { | |
162 | char c; | |
163 | if (get_user(c, data + i)) | |
164 | return -EFAULT; | |
165 | if (c == 'V') | |
166 | expect_release = true; | |
167 | } | |
168 | } | |
169 | ||
170 | /* someone wrote to us, we should reload the timer */ | |
171 | xen_wdt_kick(); | |
172 | } | |
173 | return len; | |
174 | } | |
175 | ||
176 | static long xen_wdt_ioctl(struct file *file, unsigned int cmd, | |
177 | unsigned long arg) | |
178 | { | |
179 | int new_options, retval = -EINVAL; | |
180 | int new_timeout; | |
181 | int __user *argp = (void __user *)arg; | |
182 | static const struct watchdog_info ident = { | |
183 | .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, | |
184 | .firmware_version = 0, | |
185 | .identity = DRV_NAME, | |
186 | }; | |
187 | ||
188 | switch (cmd) { | |
189 | case WDIOC_GETSUPPORT: | |
190 | return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; | |
191 | ||
192 | case WDIOC_GETSTATUS: | |
193 | case WDIOC_GETBOOTSTATUS: | |
194 | return put_user(0, argp); | |
195 | ||
196 | case WDIOC_SETOPTIONS: | |
197 | if (get_user(new_options, argp)) | |
198 | return -EFAULT; | |
199 | ||
200 | if (new_options & WDIOS_DISABLECARD) | |
201 | retval = xen_wdt_stop(); | |
202 | if (new_options & WDIOS_ENABLECARD) { | |
203 | retval = xen_wdt_start(); | |
204 | if (retval == -EBUSY) | |
205 | retval = xen_wdt_kick(); | |
206 | } | |
207 | return retval; | |
208 | ||
209 | case WDIOC_KEEPALIVE: | |
210 | xen_wdt_kick(); | |
211 | return 0; | |
212 | ||
213 | case WDIOC_SETTIMEOUT: | |
214 | if (get_user(new_timeout, argp)) | |
215 | return -EFAULT; | |
216 | if (!new_timeout) | |
217 | return -EINVAL; | |
218 | timeout = new_timeout; | |
219 | xen_wdt_kick(); | |
220 | /* fall through */ | |
221 | case WDIOC_GETTIMEOUT: | |
222 | return put_user(timeout, argp); | |
223 | ||
224 | case WDIOC_GETTIMELEFT: | |
225 | retval = wdt_expires - ktime_to_timespec(ktime_get()).tv_sec; | |
226 | return put_user(retval, argp); | |
227 | } | |
228 | ||
229 | return -ENOTTY; | |
230 | } | |
231 | ||
232 | static const struct file_operations xen_wdt_fops = { | |
233 | .owner = THIS_MODULE, | |
234 | .llseek = no_llseek, | |
235 | .write = xen_wdt_write, | |
236 | .unlocked_ioctl = xen_wdt_ioctl, | |
237 | .open = xen_wdt_open, | |
238 | .release = xen_wdt_release, | |
239 | }; | |
240 | ||
241 | static struct miscdevice xen_wdt_miscdev = { | |
242 | .minor = WATCHDOG_MINOR, | |
243 | .name = "watchdog", | |
244 | .fops = &xen_wdt_fops, | |
245 | }; | |
246 | ||
2d991a16 | 247 | static int xen_wdt_probe(struct platform_device *dev) |
066d6c7f JB |
248 | { |
249 | struct sched_watchdog wd = { .id = ~0 }; | |
250 | int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd); | |
251 | ||
252 | switch (ret) { | |
253 | case -EINVAL: | |
254 | if (!timeout) { | |
255 | timeout = WATCHDOG_TIMEOUT; | |
27c766aa | 256 | pr_info("timeout value invalid, using %d\n", timeout); |
066d6c7f JB |
257 | } |
258 | ||
259 | ret = misc_register(&xen_wdt_miscdev); | |
260 | if (ret) { | |
27c766aa | 261 | pr_err("cannot register miscdev on minor=%d (%d)\n", |
066d6c7f JB |
262 | WATCHDOG_MINOR, ret); |
263 | break; | |
264 | } | |
265 | ||
27c766aa JP |
266 | pr_info("initialized (timeout=%ds, nowayout=%d)\n", |
267 | timeout, nowayout); | |
066d6c7f JB |
268 | break; |
269 | ||
270 | case -ENOSYS: | |
27c766aa | 271 | pr_info("not supported\n"); |
066d6c7f JB |
272 | ret = -ENODEV; |
273 | break; | |
274 | ||
275 | default: | |
27c766aa | 276 | pr_info("bogus return value %d\n", ret); |
066d6c7f JB |
277 | break; |
278 | } | |
279 | ||
280 | return ret; | |
281 | } | |
282 | ||
4b12b896 | 283 | static int xen_wdt_remove(struct platform_device *dev) |
066d6c7f JB |
284 | { |
285 | /* Stop the timer before we leave */ | |
286 | if (!nowayout) | |
287 | xen_wdt_stop(); | |
288 | ||
289 | misc_deregister(&xen_wdt_miscdev); | |
290 | ||
291 | return 0; | |
292 | } | |
293 | ||
294 | static void xen_wdt_shutdown(struct platform_device *dev) | |
295 | { | |
296 | xen_wdt_stop(); | |
297 | } | |
298 | ||
299 | static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state) | |
300 | { | |
83448bf7 JB |
301 | typeof(wdt.id) id = wdt.id; |
302 | int rc = xen_wdt_stop(); | |
303 | ||
304 | wdt.id = id; | |
305 | return rc; | |
066d6c7f JB |
306 | } |
307 | ||
308 | static int xen_wdt_resume(struct platform_device *dev) | |
309 | { | |
83448bf7 JB |
310 | if (!wdt.id) |
311 | return 0; | |
312 | wdt.id = 0; | |
066d6c7f JB |
313 | return xen_wdt_start(); |
314 | } | |
315 | ||
316 | static struct platform_driver xen_wdt_driver = { | |
317 | .probe = xen_wdt_probe, | |
82268714 | 318 | .remove = xen_wdt_remove, |
066d6c7f JB |
319 | .shutdown = xen_wdt_shutdown, |
320 | .suspend = xen_wdt_suspend, | |
321 | .resume = xen_wdt_resume, | |
322 | .driver = { | |
066d6c7f JB |
323 | .name = DRV_NAME, |
324 | }, | |
325 | }; | |
326 | ||
327 | static int __init xen_wdt_init_module(void) | |
328 | { | |
329 | int err; | |
330 | ||
331 | if (!xen_domain()) | |
332 | return -ENODEV; | |
333 | ||
27c766aa | 334 | pr_info("Xen WatchDog Timer Driver v%s\n", DRV_VERSION); |
066d6c7f JB |
335 | |
336 | err = platform_driver_register(&xen_wdt_driver); | |
337 | if (err) | |
338 | return err; | |
339 | ||
340 | platform_device = platform_device_register_simple(DRV_NAME, | |
341 | -1, NULL, 0); | |
342 | if (IS_ERR(platform_device)) { | |
343 | err = PTR_ERR(platform_device); | |
344 | platform_driver_unregister(&xen_wdt_driver); | |
345 | } | |
346 | ||
347 | return err; | |
348 | } | |
349 | ||
350 | static void __exit xen_wdt_cleanup_module(void) | |
351 | { | |
352 | platform_device_unregister(platform_device); | |
353 | platform_driver_unregister(&xen_wdt_driver); | |
27c766aa | 354 | pr_info("module unloaded\n"); |
066d6c7f JB |
355 | } |
356 | ||
357 | module_init(xen_wdt_init_module); | |
358 | module_exit(xen_wdt_cleanup_module); | |
359 | ||
360 | MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>"); | |
361 | MODULE_DESCRIPTION("Xen WatchDog Timer Driver"); | |
362 | MODULE_VERSION(DRV_VERSION); | |
363 | MODULE_LICENSE("GPL"); |