Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target...
[linux-btrfs-devel.git] / drivers / watchdog / xen_wdt.c
blob49bd9d3955624fb367e3558ce71fa68e8b8b7596
1 /*
2 * Xen Watchdog Driver
4 * (c) Copyright 2010 Novell, Inc.
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.
12 #define DRV_NAME "wdt"
13 #define DRV_VERSION "0.01"
14 #define PFX DRV_NAME ": "
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>
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;
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) ")");
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) ")");
51 static inline __kernel_time_t set_timeout(void)
53 wdt.timeout = timeout;
54 return ktime_to_timespec(ktime_get()).tv_sec + timeout;
57 static int xen_wdt_start(void)
59 __kernel_time_t expires;
60 int err;
62 spin_lock(&wdt_lock);
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);
76 spin_unlock(&wdt_lock);
78 return err;
81 static int xen_wdt_stop(void)
83 int err = 0;
85 spin_lock(&wdt_lock);
87 wdt.timeout = 0;
88 if (wdt.id)
89 err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
90 if (!err)
91 wdt.id = 0;
93 spin_unlock(&wdt_lock);
95 return err;
98 static int xen_wdt_kick(void)
100 __kernel_time_t expires;
101 int err;
103 spin_lock(&wdt_lock);
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;
113 spin_unlock(&wdt_lock);
115 return err;
118 static int xen_wdt_open(struct inode *inode, struct file *file)
120 int err;
122 /* /dev/watchdog can only be opened once */
123 if (xchg(&is_active, true))
124 return -EBUSY;
126 err = xen_wdt_start();
127 if (err == -EBUSY)
128 err = xen_wdt_kick();
129 return err ?: nonseekable_open(inode, file);
132 static int xen_wdt_release(struct inode *inode, struct file *file)
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();
141 is_active = false;
142 expect_release = false;
143 return 0;
146 static ssize_t xen_wdt_write(struct file *file, const char __user *data,
147 size_t len, loff_t *ppos)
149 /* See if we got the magic character 'V' and reload the timer */
150 if (len) {
151 if (!nowayout) {
152 size_t i;
154 /* in case it was set long ago */
155 expect_release = false;
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;
168 /* someone wrote to us, we should reload the timer */
169 xen_wdt_kick();
171 return len;
174 static long xen_wdt_ioctl(struct file *file, unsigned int cmd,
175 unsigned long arg)
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,
186 switch (cmd) {
187 case WDIOC_GETSUPPORT:
188 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
190 case WDIOC_GETSTATUS:
191 case WDIOC_GETBOOTSTATUS:
192 return put_user(0, argp);
194 case WDIOC_SETOPTIONS:
195 if (get_user(new_options, argp))
196 return -EFAULT;
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();
205 return retval;
207 case WDIOC_KEEPALIVE:
208 xen_wdt_kick();
209 return 0;
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);
222 case WDIOC_GETTIMELEFT:
223 retval = wdt_expires - ktime_to_timespec(ktime_get()).tv_sec;
224 return put_user(retval, argp);
227 return -ENOTTY;
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,
239 static struct miscdevice xen_wdt_miscdev = {
240 .minor = WATCHDOG_MINOR,
241 .name = "watchdog",
242 .fops = &xen_wdt_fops,
245 static int __devinit xen_wdt_probe(struct platform_device *dev)
247 struct sched_watchdog wd = { .id = ~0 };
248 int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
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);
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;
266 printk(KERN_INFO PFX
267 "initialized (timeout=%ds, nowayout=%d)\n",
268 timeout, nowayout);
269 break;
271 case -ENOSYS:
272 printk(KERN_INFO PFX "not supported\n");
273 ret = -ENODEV;
274 break;
276 default:
277 printk(KERN_INFO PFX "bogus return value %d\n", ret);
278 break;
281 return ret;
284 static int __devexit xen_wdt_remove(struct platform_device *dev)
286 /* Stop the timer before we leave */
287 if (!nowayout)
288 xen_wdt_stop();
290 misc_deregister(&xen_wdt_miscdev);
292 return 0;
295 static void xen_wdt_shutdown(struct platform_device *dev)
297 xen_wdt_stop();
300 static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
302 return xen_wdt_stop();
305 static int xen_wdt_resume(struct platform_device *dev)
307 return xen_wdt_start();
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,
322 static int __init xen_wdt_init_module(void)
324 int err;
326 if (!xen_domain())
327 return -ENODEV;
329 printk(KERN_INFO PFX "Xen WatchDog Timer Driver v%s\n", DRV_VERSION);
331 err = platform_driver_register(&xen_wdt_driver);
332 if (err)
333 return err;
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);
342 return err;
345 static void __exit xen_wdt_cleanup_module(void)
347 platform_device_unregister(platform_device);
348 platform_driver_unregister(&xen_wdt_driver);
349 printk(KERN_INFO PFX "module unloaded\n");
352 module_init(xen_wdt_init_module);
353 module_exit(xen_wdt_cleanup_module);
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);