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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
12#define DRV_NAME "wdt"
13#define DRV_VERSION "0.01"
14#define PFX DRV_NAME ": "
15
16#include <linux/bug.h>
17#include <linux/errno.h>
18#include <linux/fs.h>
19#include <linux/hrtimer.h>
20#include <linux/kernel.h>
21#include <linux/ktime.h>
22#include <linux/init.h>
23#include <linux/miscdevice.h>
24#include <linux/module.h>
25#include <linux/moduleparam.h>
26#include <linux/platform_device.h>
27#include <linux/spinlock.h>
28#include <linux/uaccess.h>
29#include <linux/watchdog.h>
30#include <xen/xen.h>
31#include <asm/xen/hypercall.h>
32#include <xen/interface/sched.h>
33
34static struct platform_device *platform_device;
35static DEFINE_SPINLOCK(wdt_lock);
36static struct sched_watchdog wdt;
37static __kernel_time_t wdt_expires;
38static bool is_active, expect_release;
39
40#define WATCHDOG_TIMEOUT 60 /* in seconds */
41static unsigned int timeout = WATCHDOG_TIMEOUT;
42module_param(timeout, uint, S_IRUGO);
43MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
44 "(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
45
46static bool nowayout = WATCHDOG_NOWAYOUT;
47module_param(nowayout, bool, S_IRUGO);
48MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
49 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
50
51static inline __kernel_time_t set_timeout(void)
52{
53 wdt.timeout = timeout;
54 return ktime_to_timespec(ktime_get()).tv_sec + timeout;
55}
56
57static int xen_wdt_start(void)
58{
59 __kernel_time_t expires;
60 int err;
61
62 spin_lock(&wdt_lock);
63
64 expires = set_timeout();
65 if (!wdt.id)
66 err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
67 else
68 err = -EBUSY;
69 if (err > 0) {
70 wdt.id = err;
71 wdt_expires = expires;
72 err = 0;
73 } else
74 BUG_ON(!err);
75
76 spin_unlock(&wdt_lock);
77
78 return err;
79}
80
81static int xen_wdt_stop(void)
82{
83 int err = 0;
84
85 spin_lock(&wdt_lock);
86
87 wdt.timeout = 0;
88 if (wdt.id)
89 err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
90 if (!err)
91 wdt.id = 0;
92
93 spin_unlock(&wdt_lock);
94
95 return err;
96}
97
98static int xen_wdt_kick(void)
99{
100 __kernel_time_t expires;
101 int err;
102
103 spin_lock(&wdt_lock);
104
105 expires = set_timeout();
106 if (wdt.id)
107 err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
108 else
109 err = -ENXIO;
110 if (!err)
111 wdt_expires = expires;
112
113 spin_unlock(&wdt_lock);
114
115 return err;
116}
117
118static int xen_wdt_open(struct inode *inode, struct file *file)
119{
120 int err;
121
122 /* /dev/watchdog can only be opened once */
123 if (xchg(&is_active, true))
124 return -EBUSY;
125
126 err = xen_wdt_start();
127 if (err == -EBUSY)
128 err = xen_wdt_kick();
129 return err ?: nonseekable_open(inode, file);
130}
131
132static int xen_wdt_release(struct inode *inode, struct file *file)
133{
134 if (expect_release)
135 xen_wdt_stop();
136 else {
137 printk(KERN_CRIT PFX
138 "unexpected close, not stopping watchdog!\n");
139 xen_wdt_kick();
140 }
141 is_active = false;
142 expect_release = false;
143 return 0;
144}
145
146static 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
174static 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
230static 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
239static struct miscdevice xen_wdt_miscdev = {
240 .minor = WATCHDOG_MINOR,
241 .name = "watchdog",
242 .fops = &xen_wdt_fops,
243};
244
245static 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;
254 printk(KERN_INFO PFX
255 "timeout value invalid, using %d\n", timeout);
256 }
257
258 ret = misc_register(&xen_wdt_miscdev);
259 if (ret) {
260 printk(KERN_ERR PFX
261 "cannot register miscdev on minor=%d (%d)\n",
262 WATCHDOG_MINOR, ret);
263 break;
264 }
265
266 printk(KERN_INFO PFX
267 "initialized (timeout=%ds, nowayout=%d)\n",
268 timeout, nowayout);
269 break;
270
271 case -ENOSYS:
272 printk(KERN_INFO PFX "not supported\n");
273 ret = -ENODEV;
274 break;
275
276 default:
277 printk(KERN_INFO PFX "bogus return value %d\n", ret);
278 break;
279 }
280
281 return ret;
282}
283
284static int __devexit xen_wdt_remove(struct platform_device *dev)
285{
286 /* Stop the timer before we leave */
287 if (!nowayout)
288 xen_wdt_stop();
289
290 misc_deregister(&xen_wdt_miscdev);
291
292 return 0;
293}
294
295static void xen_wdt_shutdown(struct platform_device *dev)
296{
297 xen_wdt_stop();
298}
299
300static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
301{
302 return xen_wdt_stop();
303}
304
305static int xen_wdt_resume(struct platform_device *dev)
306{
307 return xen_wdt_start();
308}
309
310static struct platform_driver xen_wdt_driver = {
311 .probe = xen_wdt_probe,
312 .remove = __devexit_p(xen_wdt_remove),
313 .shutdown = xen_wdt_shutdown,
314 .suspend = xen_wdt_suspend,
315 .resume = xen_wdt_resume,
316 .driver = {
317 .owner = THIS_MODULE,
318 .name = DRV_NAME,
319 },
320};
321
322static int __init xen_wdt_init_module(void)
323{
324 int err;
325
326 if (!xen_domain())
327 return -ENODEV;
328
329 printk(KERN_INFO PFX "Xen WatchDog Timer Driver v%s\n", DRV_VERSION);
330
331 err = platform_driver_register(&xen_wdt_driver);
332 if (err)
333 return err;
334
335 platform_device = platform_device_register_simple(DRV_NAME,
336 -1, NULL, 0);
337 if (IS_ERR(platform_device)) {
338 err = PTR_ERR(platform_device);
339 platform_driver_unregister(&xen_wdt_driver);
340 }
341
342 return err;
343}
344
345static void __exit xen_wdt_cleanup_module(void)
346{
347 platform_device_unregister(platform_device);
348 platform_driver_unregister(&xen_wdt_driver);
349 printk(KERN_INFO PFX "module unloaded\n");
350}
351
352module_init(xen_wdt_init_module);
353module_exit(xen_wdt_cleanup_module);
354
355MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>");
356MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
357MODULE_VERSION(DRV_VERSION);
358MODULE_LICENSE("GPL");
359MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
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
12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14#define DRV_NAME "wdt"
15#define DRV_VERSION "0.01"
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
35static struct platform_device *platform_device;
36static DEFINE_SPINLOCK(wdt_lock);
37static struct sched_watchdog wdt;
38static __kernel_time_t wdt_expires;
39static bool is_active, expect_release;
40
41#define WATCHDOG_TIMEOUT 60 /* in seconds */
42static unsigned int timeout = WATCHDOG_TIMEOUT;
43module_param(timeout, uint, S_IRUGO);
44MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
45 "(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
46
47static bool nowayout = WATCHDOG_NOWAYOUT;
48module_param(nowayout, bool, S_IRUGO);
49MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
50 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
51
52static inline __kernel_time_t set_timeout(void)
53{
54 wdt.timeout = timeout;
55 return ktime_to_timespec(ktime_get()).tv_sec + timeout;
56}
57
58static 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
82static 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
99static 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
119static 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
133static int xen_wdt_release(struct inode *inode, struct file *file)
134{
135 int err = 0;
136
137 if (expect_release)
138 err = xen_wdt_stop();
139 else {
140 pr_crit("unexpected close, not stopping watchdog!\n");
141 xen_wdt_kick();
142 }
143 is_active = err;
144 expect_release = false;
145 return err;
146}
147
148static 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
176static 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
232static 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
241static struct miscdevice xen_wdt_miscdev = {
242 .minor = WATCHDOG_MINOR,
243 .name = "watchdog",
244 .fops = &xen_wdt_fops,
245};
246
247static int xen_wdt_probe(struct platform_device *dev)
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;
256 pr_info("timeout value invalid, using %d\n", timeout);
257 }
258
259 ret = misc_register(&xen_wdt_miscdev);
260 if (ret) {
261 pr_err("cannot register miscdev on minor=%d (%d)\n",
262 WATCHDOG_MINOR, ret);
263 break;
264 }
265
266 pr_info("initialized (timeout=%ds, nowayout=%d)\n",
267 timeout, nowayout);
268 break;
269
270 case -ENOSYS:
271 pr_info("not supported\n");
272 ret = -ENODEV;
273 break;
274
275 default:
276 pr_info("bogus return value %d\n", ret);
277 break;
278 }
279
280 return ret;
281}
282
283static int xen_wdt_remove(struct platform_device *dev)
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
294static void xen_wdt_shutdown(struct platform_device *dev)
295{
296 xen_wdt_stop();
297}
298
299static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
300{
301 typeof(wdt.id) id = wdt.id;
302 int rc = xen_wdt_stop();
303
304 wdt.id = id;
305 return rc;
306}
307
308static int xen_wdt_resume(struct platform_device *dev)
309{
310 if (!wdt.id)
311 return 0;
312 wdt.id = 0;
313 return xen_wdt_start();
314}
315
316static struct platform_driver xen_wdt_driver = {
317 .probe = xen_wdt_probe,
318 .remove = xen_wdt_remove,
319 .shutdown = xen_wdt_shutdown,
320 .suspend = xen_wdt_suspend,
321 .resume = xen_wdt_resume,
322 .driver = {
323 .name = DRV_NAME,
324 },
325};
326
327static int __init xen_wdt_init_module(void)
328{
329 int err;
330
331 if (!xen_domain())
332 return -ENODEV;
333
334 pr_info("Xen WatchDog Timer Driver v%s\n", DRV_VERSION);
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
350static void __exit xen_wdt_cleanup_module(void)
351{
352 platform_device_unregister(platform_device);
353 platform_driver_unregister(&xen_wdt_driver);
354 pr_info("module unloaded\n");
355}
356
357module_init(xen_wdt_init_module);
358module_exit(xen_wdt_cleanup_module);
359
360MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>");
361MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
362MODULE_VERSION(DRV_VERSION);
363MODULE_LICENSE("GPL");