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1da177e4 LT |
1 | /* |
2 | * drivers/char/watchdog/shwdt.c | |
3 | * | |
4 | * Watchdog driver for integrated watchdog in the SuperH processors. | |
5 | * | |
6 | * Copyright (C) 2001, 2002, 2003 Paul Mundt <lethal@linux-sh.org> | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify it | |
9 | * under the terms of the GNU General Public License as published by the | |
10 | * Free Software Foundation; either version 2 of the License, or (at your | |
11 | * option) any later version. | |
12 | * | |
13 | * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com> | |
14 | * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT | |
15 | * | |
16 | * 19-Apr-2002 Rob Radez <rob@osinvestor.com> | |
17 | * Added expect close support, made emulated timeout runtime changeable | |
18 | * general cleanups, add some ioctls | |
19 | */ | |
1da177e4 LT |
20 | #include <linux/module.h> |
21 | #include <linux/moduleparam.h> | |
22 | #include <linux/init.h> | |
23 | #include <linux/types.h> | |
24 | #include <linux/miscdevice.h> | |
25 | #include <linux/watchdog.h> | |
26 | #include <linux/reboot.h> | |
27 | #include <linux/notifier.h> | |
28 | #include <linux/ioport.h> | |
29 | #include <linux/fs.h> | |
30 | ||
31 | #include <asm/io.h> | |
32 | #include <asm/uaccess.h> | |
33 | #include <asm/watchdog.h> | |
34 | ||
35 | #define PFX "shwdt: " | |
36 | ||
37 | /* | |
38 | * Default clock division ratio is 5.25 msecs. For an additional table of | |
39 | * values, consult the asm-sh/watchdog.h. Overload this at module load | |
40 | * time. | |
41 | * | |
42 | * In order for this to work reliably we need to have HZ set to 1000 or | |
43 | * something quite higher than 100 (or we need a proper high-res timer | |
44 | * implementation that will deal with this properly), otherwise the 10ms | |
45 | * resolution of a jiffy is enough to trigger the overflow. For things like | |
46 | * the SH-4 and SH-5, this isn't necessarily that big of a problem, though | |
47 | * for the SH-2 and SH-3, this isn't recommended unless the WDT is absolutely | |
48 | * necssary. | |
49 | * | |
50 | * As a result of this timing problem, the only modes that are particularly | |
51 | * feasible are the 4096 and the 2048 divisors, which yeild 5.25 and 2.62ms | |
52 | * overflow periods respectively. | |
53 | * | |
54 | * Also, since we can't really expect userspace to be responsive enough | |
55 | * before the overflow happens, we maintain two seperate timers .. One in | |
56 | * the kernel for clearing out WOVF every 2ms or so (again, this depends on | |
57 | * HZ == 1000), and another for monitoring userspace writes to the WDT device. | |
58 | * | |
59 | * As such, we currently use a configurable heartbeat interval which defaults | |
60 | * to 30s. In this case, the userspace daemon is only responsible for periodic | |
61 | * writes to the device before the next heartbeat is scheduled. If the daemon | |
62 | * misses its deadline, the kernel timer will allow the WDT to overflow. | |
63 | */ | |
64 | static int clock_division_ratio = WTCSR_CKS_4096; | |
65 | ||
66 | #define next_ping_period(cks) msecs_to_jiffies(cks - 4) | |
67 | ||
68 | static unsigned long shwdt_is_open; | |
69 | static struct watchdog_info sh_wdt_info; | |
70 | static char shwdt_expect_close; | |
71 | static struct timer_list timer; | |
72 | static unsigned long next_heartbeat; | |
73 | ||
74 | #define WATCHDOG_HEARTBEAT 30 /* 30 sec default heartbeat */ | |
75 | static int heartbeat = WATCHDOG_HEARTBEAT; /* in seconds */ | |
76 | ||
4bfdf378 | 77 | static int nowayout = WATCHDOG_NOWAYOUT; |
1da177e4 LT |
78 | |
79 | /** | |
80 | * sh_wdt_start - Start the Watchdog | |
81 | * | |
82 | * Starts the watchdog. | |
83 | */ | |
84 | static void sh_wdt_start(void) | |
85 | { | |
86 | __u8 csr; | |
87 | ||
88 | next_heartbeat = jiffies + (heartbeat * HZ); | |
89 | mod_timer(&timer, next_ping_period(clock_division_ratio)); | |
90 | ||
91 | csr = sh_wdt_read_csr(); | |
92 | csr |= WTCSR_WT | clock_division_ratio; | |
93 | sh_wdt_write_csr(csr); | |
94 | ||
95 | sh_wdt_write_cnt(0); | |
96 | ||
97 | /* | |
98 | * These processors have a bit of an inconsistent initialization | |
99 | * process.. starting with SH-3, RSTS was moved to WTCSR, and the | |
100 | * RSTCSR register was removed. | |
101 | * | |
102 | * On the SH-2 however, in addition with bits being in different | |
103 | * locations, we must deal with RSTCSR outright.. | |
104 | */ | |
105 | csr = sh_wdt_read_csr(); | |
106 | csr |= WTCSR_TME; | |
107 | csr &= ~WTCSR_RSTS; | |
108 | sh_wdt_write_csr(csr); | |
109 | ||
110 | #ifdef CONFIG_CPU_SH2 | |
111 | /* | |
112 | * Whoever came up with the RSTCSR semantics must've been smoking | |
113 | * some of the good stuff, since in addition to the WTCSR/WTCNT write | |
114 | * brain-damage, it's managed to fuck things up one step further.. | |
115 | * | |
116 | * If we need to clear the WOVF bit, the upper byte has to be 0xa5.. | |
117 | * but if we want to touch RSTE or RSTS, the upper byte has to be | |
118 | * 0x5a.. | |
119 | */ | |
120 | csr = sh_wdt_read_rstcsr(); | |
121 | csr &= ~RSTCSR_RSTS; | |
122 | sh_wdt_write_rstcsr(csr); | |
123 | #endif | |
124 | } | |
125 | ||
126 | /** | |
127 | * sh_wdt_stop - Stop the Watchdog | |
1da177e4 LT |
128 | * Stops the watchdog. |
129 | */ | |
130 | static void sh_wdt_stop(void) | |
131 | { | |
132 | __u8 csr; | |
133 | ||
134 | del_timer(&timer); | |
135 | ||
136 | csr = sh_wdt_read_csr(); | |
137 | csr &= ~WTCSR_TME; | |
138 | sh_wdt_write_csr(csr); | |
139 | } | |
140 | ||
141 | /** | |
142 | * sh_wdt_keepalive - Keep the Userspace Watchdog Alive | |
1da177e4 LT |
143 | * The Userspace watchdog got a KeepAlive: schedule the next heartbeat. |
144 | */ | |
e4c2cfee | 145 | static inline void sh_wdt_keepalive(void) |
1da177e4 LT |
146 | { |
147 | next_heartbeat = jiffies + (heartbeat * HZ); | |
148 | } | |
149 | ||
150 | /** | |
151 | * sh_wdt_set_heartbeat - Set the Userspace Watchdog heartbeat | |
1da177e4 LT |
152 | * Set the Userspace Watchdog heartbeat |
153 | */ | |
154 | static int sh_wdt_set_heartbeat(int t) | |
155 | { | |
e4c2cfee | 156 | if (unlikely((t < 1) || (t > 3600))) /* arbitrary upper limit */ |
1da177e4 LT |
157 | return -EINVAL; |
158 | ||
159 | heartbeat = t; | |
160 | return 0; | |
161 | } | |
162 | ||
163 | /** | |
164 | * sh_wdt_ping - Ping the Watchdog | |
1da177e4 LT |
165 | * @data: Unused |
166 | * | |
167 | * Clears overflow bit, resets timer counter. | |
168 | */ | |
169 | static void sh_wdt_ping(unsigned long data) | |
170 | { | |
171 | if (time_before(jiffies, next_heartbeat)) { | |
172 | __u8 csr; | |
173 | ||
174 | csr = sh_wdt_read_csr(); | |
175 | csr &= ~WTCSR_IOVF; | |
176 | sh_wdt_write_csr(csr); | |
177 | ||
178 | sh_wdt_write_cnt(0); | |
179 | ||
180 | mod_timer(&timer, next_ping_period(clock_division_ratio)); | |
e4c2cfee PM |
181 | } else |
182 | printk(KERN_WARNING PFX "Heartbeat lost! Will not ping " | |
183 | "the watchdog\n"); | |
1da177e4 LT |
184 | } |
185 | ||
186 | /** | |
187 | * sh_wdt_open - Open the Device | |
1da177e4 LT |
188 | * @inode: inode of device |
189 | * @file: file handle of device | |
190 | * | |
191 | * Watchdog device is opened and started. | |
192 | */ | |
193 | static int sh_wdt_open(struct inode *inode, struct file *file) | |
194 | { | |
195 | if (test_and_set_bit(0, &shwdt_is_open)) | |
196 | return -EBUSY; | |
197 | if (nowayout) | |
198 | __module_get(THIS_MODULE); | |
199 | ||
200 | sh_wdt_start(); | |
201 | ||
202 | return nonseekable_open(inode, file); | |
203 | } | |
204 | ||
205 | /** | |
206 | * sh_wdt_close - Close the Device | |
1da177e4 LT |
207 | * @inode: inode of device |
208 | * @file: file handle of device | |
209 | * | |
210 | * Watchdog device is closed and stopped. | |
211 | */ | |
212 | static int sh_wdt_close(struct inode *inode, struct file *file) | |
213 | { | |
214 | if (shwdt_expect_close == 42) { | |
215 | sh_wdt_stop(); | |
216 | } else { | |
e4c2cfee PM |
217 | printk(KERN_CRIT PFX "Unexpected close, not " |
218 | "stopping watchdog!\n"); | |
1da177e4 LT |
219 | sh_wdt_keepalive(); |
220 | } | |
221 | ||
222 | clear_bit(0, &shwdt_is_open); | |
223 | shwdt_expect_close = 0; | |
224 | ||
225 | return 0; | |
226 | } | |
227 | ||
228 | /** | |
229 | * sh_wdt_write - Write to Device | |
1da177e4 LT |
230 | * @file: file handle of device |
231 | * @buf: buffer to write | |
232 | * @count: length of buffer | |
233 | * @ppos: offset | |
234 | * | |
235 | * Pings the watchdog on write. | |
236 | */ | |
237 | static ssize_t sh_wdt_write(struct file *file, const char *buf, | |
238 | size_t count, loff_t *ppos) | |
239 | { | |
240 | if (count) { | |
241 | if (!nowayout) { | |
242 | size_t i; | |
243 | ||
244 | shwdt_expect_close = 0; | |
245 | ||
246 | for (i = 0; i != count; i++) { | |
247 | char c; | |
248 | if (get_user(c, buf + i)) | |
249 | return -EFAULT; | |
250 | if (c == 'V') | |
251 | shwdt_expect_close = 42; | |
252 | } | |
253 | } | |
254 | sh_wdt_keepalive(); | |
255 | } | |
256 | ||
257 | return count; | |
258 | } | |
259 | ||
260 | /** | |
261 | * sh_wdt_ioctl - Query Device | |
1da177e4 LT |
262 | * @inode: inode of device |
263 | * @file: file handle of device | |
264 | * @cmd: watchdog command | |
265 | * @arg: argument | |
266 | * | |
267 | * Query basic information from the device or ping it, as outlined by the | |
268 | * watchdog API. | |
269 | */ | |
270 | static int sh_wdt_ioctl(struct inode *inode, struct file *file, | |
271 | unsigned int cmd, unsigned long arg) | |
272 | { | |
273 | int new_heartbeat; | |
274 | int options, retval = -EINVAL; | |
275 | ||
276 | switch (cmd) { | |
277 | case WDIOC_GETSUPPORT: | |
278 | return copy_to_user((struct watchdog_info *)arg, | |
279 | &sh_wdt_info, | |
280 | sizeof(sh_wdt_info)) ? -EFAULT : 0; | |
281 | case WDIOC_GETSTATUS: | |
282 | case WDIOC_GETBOOTSTATUS: | |
283 | return put_user(0, (int *)arg); | |
284 | case WDIOC_KEEPALIVE: | |
285 | sh_wdt_keepalive(); | |
286 | return 0; | |
287 | case WDIOC_SETTIMEOUT: | |
288 | if (get_user(new_heartbeat, (int *)arg)) | |
289 | return -EFAULT; | |
290 | ||
291 | if (sh_wdt_set_heartbeat(new_heartbeat)) | |
292 | return -EINVAL; | |
293 | ||
294 | sh_wdt_keepalive(); | |
295 | /* Fall */ | |
296 | case WDIOC_GETTIMEOUT: | |
297 | return put_user(heartbeat, (int *)arg); | |
298 | case WDIOC_SETOPTIONS: | |
299 | if (get_user(options, (int *)arg)) | |
300 | return -EFAULT; | |
301 | ||
302 | if (options & WDIOS_DISABLECARD) { | |
303 | sh_wdt_stop(); | |
304 | retval = 0; | |
305 | } | |
306 | ||
307 | if (options & WDIOS_ENABLECARD) { | |
308 | sh_wdt_start(); | |
309 | retval = 0; | |
310 | } | |
311 | ||
312 | return retval; | |
313 | default: | |
314 | return -ENOIOCTLCMD; | |
315 | } | |
316 | ||
317 | return 0; | |
318 | } | |
319 | ||
320 | /** | |
321 | * sh_wdt_notify_sys - Notifier Handler | |
1da177e4 LT |
322 | * @this: notifier block |
323 | * @code: notifier event | |
324 | * @unused: unused | |
325 | * | |
326 | * Handles specific events, such as turning off the watchdog during a | |
327 | * shutdown event. | |
328 | */ | |
329 | static int sh_wdt_notify_sys(struct notifier_block *this, | |
330 | unsigned long code, void *unused) | |
331 | { | |
e4c2cfee | 332 | if (code == SYS_DOWN || code == SYS_HALT) |
1da177e4 | 333 | sh_wdt_stop(); |
1da177e4 LT |
334 | |
335 | return NOTIFY_DONE; | |
336 | } | |
337 | ||
62322d25 | 338 | static const struct file_operations sh_wdt_fops = { |
1da177e4 LT |
339 | .owner = THIS_MODULE, |
340 | .llseek = no_llseek, | |
341 | .write = sh_wdt_write, | |
342 | .ioctl = sh_wdt_ioctl, | |
343 | .open = sh_wdt_open, | |
344 | .release = sh_wdt_close, | |
345 | }; | |
346 | ||
347 | static struct watchdog_info sh_wdt_info = { | |
e4c2cfee PM |
348 | .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | |
349 | WDIOF_MAGICCLOSE, | |
1da177e4 LT |
350 | .firmware_version = 1, |
351 | .identity = "SH WDT", | |
352 | }; | |
353 | ||
354 | static struct notifier_block sh_wdt_notifier = { | |
355 | .notifier_call = sh_wdt_notify_sys, | |
356 | }; | |
357 | ||
358 | static struct miscdevice sh_wdt_miscdev = { | |
359 | .minor = WATCHDOG_MINOR, | |
360 | .name = "watchdog", | |
361 | .fops = &sh_wdt_fops, | |
362 | }; | |
363 | ||
364 | /** | |
365 | * sh_wdt_init - Initialize module | |
1da177e4 LT |
366 | * Registers the device and notifier handler. Actual device |
367 | * initialization is handled by sh_wdt_open(). | |
368 | */ | |
369 | static int __init sh_wdt_init(void) | |
370 | { | |
371 | int rc; | |
372 | ||
373 | if ((clock_division_ratio < 0x5) || (clock_division_ratio > 0x7)) { | |
374 | clock_division_ratio = WTCSR_CKS_4096; | |
e4c2cfee PM |
375 | printk(KERN_INFO PFX "clock_division_ratio value must " |
376 | "be 0x5<=x<=0x7, using %d\n", clock_division_ratio); | |
1da177e4 LT |
377 | } |
378 | ||
e4c2cfee PM |
379 | rc = sh_wdt_set_heartbeat(heartbeat); |
380 | if (unlikely(rc)) { | |
1da177e4 | 381 | heartbeat = WATCHDOG_HEARTBEAT; |
e4c2cfee PM |
382 | printk(KERN_INFO PFX "heartbeat value must " |
383 | "be 1<=x<=3600, using %d\n", heartbeat); | |
1da177e4 LT |
384 | } |
385 | ||
386 | init_timer(&timer); | |
387 | timer.function = sh_wdt_ping; | |
388 | timer.data = 0; | |
389 | ||
390 | rc = register_reboot_notifier(&sh_wdt_notifier); | |
e4c2cfee PM |
391 | if (unlikely(rc)) { |
392 | printk(KERN_ERR PFX "Can't register reboot notifier (err=%d)\n", | |
393 | rc); | |
1da177e4 LT |
394 | return rc; |
395 | } | |
396 | ||
397 | rc = misc_register(&sh_wdt_miscdev); | |
e4c2cfee PM |
398 | if (unlikely(rc)) { |
399 | printk(KERN_ERR PFX "Can't register miscdev on " | |
400 | "minor=%d (err=%d)\n", sh_wdt_miscdev.minor, rc); | |
1da177e4 LT |
401 | unregister_reboot_notifier(&sh_wdt_notifier); |
402 | return rc; | |
403 | } | |
404 | ||
405 | printk(KERN_INFO PFX "initialized. heartbeat=%d sec (nowayout=%d)\n", | |
406 | heartbeat, nowayout); | |
407 | ||
408 | return 0; | |
409 | } | |
410 | ||
411 | /** | |
412 | * sh_wdt_exit - Deinitialize module | |
1da177e4 LT |
413 | * Unregisters the device and notifier handler. Actual device |
414 | * deinitialization is handled by sh_wdt_close(). | |
415 | */ | |
416 | static void __exit sh_wdt_exit(void) | |
417 | { | |
418 | misc_deregister(&sh_wdt_miscdev); | |
419 | unregister_reboot_notifier(&sh_wdt_notifier); | |
420 | } | |
421 | ||
422 | MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>"); | |
423 | MODULE_DESCRIPTION("SuperH watchdog driver"); | |
424 | MODULE_LICENSE("GPL"); | |
425 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); | |
426 | ||
427 | module_param(clock_division_ratio, int, 0); | |
e4c2cfee | 428 | MODULE_PARM_DESC(clock_division_ratio, "Clock division ratio. Valid ranges are from 0x5 (1.31ms) to 0x7 (5.25ms). (default=" __MODULE_STRING(clock_division_ratio) ")"); |
1da177e4 LT |
429 | |
430 | module_param(heartbeat, int, 0); | |
431 | MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (1<=heartbeat<=3600, default=" __MODULE_STRING(WATCHDOG_HEARTBEAT) ")"); | |
432 | ||
433 | module_param(nowayout, int, 0); | |
e4c2cfee | 434 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
1da177e4 LT |
435 | |
436 | module_init(sh_wdt_init); | |
437 | module_exit(sh_wdt_exit); |