Merge branch 'kvm-updates/2.6.39' of git://git.kernel.org/pub/scm/virt/kvm/kvm
[pandora-kernel.git] / drivers / watchdog / xen_wdt.c
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
34 static struct platform_device *platform_device;
35 static DEFINE_SPINLOCK(wdt_lock);
36 static struct sched_watchdog wdt;
37 static __kernel_time_t wdt_expires;
38 static bool is_active, expect_release;
39
40 #define WATCHDOG_TIMEOUT 60 /* in seconds */
41 static unsigned int timeout = WATCHDOG_TIMEOUT;
42 module_param(timeout, uint, S_IRUGO);
43 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
44         "(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
45
46 static bool nowayout = WATCHDOG_NOWAYOUT;
47 module_param(nowayout, bool, S_IRUGO);
48 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
49         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
50
51 static inline __kernel_time_t set_timeout(void)
52 {
53         wdt.timeout = timeout;
54         return ktime_to_timespec(ktime_get()).tv_sec + timeout;
55 }
56
57 static 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
81 static 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
98 static 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
118 static 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
132 static 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
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;
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
284 static 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
295 static void xen_wdt_shutdown(struct platform_device *dev)
296 {
297         xen_wdt_stop();
298 }
299
300 static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
301 {
302         return xen_wdt_stop();
303 }
304
305 static int xen_wdt_resume(struct platform_device *dev)
306 {
307         return xen_wdt_start();
308 }
309
310 static 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
322 static 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
345 static 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
352 module_init(xen_wdt_init_module);
353 module_exit(xen_wdt_cleanup_module);
354
355 MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>");
356 MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
357 MODULE_VERSION(DRV_VERSION);
358 MODULE_LICENSE("GPL");
359 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);