Commit | Line | Data |
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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> | |
f118420b | 30 | #include <linux/mm.h> |
1da177e4 LT |
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 | |
ee0fc097 | 55 | * before the overflow happens, we maintain two separate timers .. One in |
1da177e4 LT |
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 | ||
82eb7c50 JS |
68 | static void sh_wdt_ping(unsigned long data); |
69 | ||
1da177e4 LT |
70 | static unsigned long shwdt_is_open; |
71 | static struct watchdog_info sh_wdt_info; | |
72 | static char shwdt_expect_close; | |
82eb7c50 | 73 | static DEFINE_TIMER(timer, sh_wdt_ping, 0, 0); |
1da177e4 LT |
74 | static unsigned long next_heartbeat; |
75 | ||
76 | #define WATCHDOG_HEARTBEAT 30 /* 30 sec default heartbeat */ | |
77 | static int heartbeat = WATCHDOG_HEARTBEAT; /* in seconds */ | |
78 | ||
4bfdf378 | 79 | static int nowayout = WATCHDOG_NOWAYOUT; |
1da177e4 LT |
80 | |
81 | /** | |
82 | * sh_wdt_start - Start the Watchdog | |
83 | * | |
84 | * Starts the watchdog. | |
85 | */ | |
86 | static void sh_wdt_start(void) | |
87 | { | |
88 | __u8 csr; | |
89 | ||
90 | next_heartbeat = jiffies + (heartbeat * HZ); | |
91 | mod_timer(&timer, next_ping_period(clock_division_ratio)); | |
92 | ||
93 | csr = sh_wdt_read_csr(); | |
94 | csr |= WTCSR_WT | clock_division_ratio; | |
95 | sh_wdt_write_csr(csr); | |
96 | ||
97 | sh_wdt_write_cnt(0); | |
98 | ||
99 | /* | |
100 | * These processors have a bit of an inconsistent initialization | |
101 | * process.. starting with SH-3, RSTS was moved to WTCSR, and the | |
102 | * RSTCSR register was removed. | |
103 | * | |
104 | * On the SH-2 however, in addition with bits being in different | |
105 | * locations, we must deal with RSTCSR outright.. | |
106 | */ | |
107 | csr = sh_wdt_read_csr(); | |
108 | csr |= WTCSR_TME; | |
109 | csr &= ~WTCSR_RSTS; | |
110 | sh_wdt_write_csr(csr); | |
111 | ||
112 | #ifdef CONFIG_CPU_SH2 | |
113 | /* | |
114 | * Whoever came up with the RSTCSR semantics must've been smoking | |
115 | * some of the good stuff, since in addition to the WTCSR/WTCNT write | |
116 | * brain-damage, it's managed to fuck things up one step further.. | |
117 | * | |
118 | * If we need to clear the WOVF bit, the upper byte has to be 0xa5.. | |
119 | * but if we want to touch RSTE or RSTS, the upper byte has to be | |
120 | * 0x5a.. | |
121 | */ | |
122 | csr = sh_wdt_read_rstcsr(); | |
123 | csr &= ~RSTCSR_RSTS; | |
124 | sh_wdt_write_rstcsr(csr); | |
125 | #endif | |
126 | } | |
127 | ||
128 | /** | |
129 | * sh_wdt_stop - Stop the Watchdog | |
1da177e4 LT |
130 | * Stops the watchdog. |
131 | */ | |
132 | static void sh_wdt_stop(void) | |
133 | { | |
134 | __u8 csr; | |
135 | ||
136 | del_timer(&timer); | |
137 | ||
138 | csr = sh_wdt_read_csr(); | |
139 | csr &= ~WTCSR_TME; | |
140 | sh_wdt_write_csr(csr); | |
141 | } | |
142 | ||
143 | /** | |
144 | * sh_wdt_keepalive - Keep the Userspace Watchdog Alive | |
1da177e4 LT |
145 | * The Userspace watchdog got a KeepAlive: schedule the next heartbeat. |
146 | */ | |
e4c2cfee | 147 | static inline void sh_wdt_keepalive(void) |
1da177e4 LT |
148 | { |
149 | next_heartbeat = jiffies + (heartbeat * HZ); | |
150 | } | |
151 | ||
152 | /** | |
153 | * sh_wdt_set_heartbeat - Set the Userspace Watchdog heartbeat | |
1da177e4 LT |
154 | * Set the Userspace Watchdog heartbeat |
155 | */ | |
156 | static int sh_wdt_set_heartbeat(int t) | |
157 | { | |
e4c2cfee | 158 | if (unlikely((t < 1) || (t > 3600))) /* arbitrary upper limit */ |
1da177e4 LT |
159 | return -EINVAL; |
160 | ||
161 | heartbeat = t; | |
162 | return 0; | |
163 | } | |
164 | ||
165 | /** | |
166 | * sh_wdt_ping - Ping the Watchdog | |
1da177e4 LT |
167 | * @data: Unused |
168 | * | |
169 | * Clears overflow bit, resets timer counter. | |
170 | */ | |
171 | static void sh_wdt_ping(unsigned long data) | |
172 | { | |
173 | if (time_before(jiffies, next_heartbeat)) { | |
174 | __u8 csr; | |
175 | ||
176 | csr = sh_wdt_read_csr(); | |
177 | csr &= ~WTCSR_IOVF; | |
178 | sh_wdt_write_csr(csr); | |
179 | ||
180 | sh_wdt_write_cnt(0); | |
181 | ||
182 | mod_timer(&timer, next_ping_period(clock_division_ratio)); | |
e4c2cfee PM |
183 | } else |
184 | printk(KERN_WARNING PFX "Heartbeat lost! Will not ping " | |
185 | "the watchdog\n"); | |
1da177e4 LT |
186 | } |
187 | ||
188 | /** | |
189 | * sh_wdt_open - Open the Device | |
1da177e4 LT |
190 | * @inode: inode of device |
191 | * @file: file handle of device | |
192 | * | |
193 | * Watchdog device is opened and started. | |
194 | */ | |
195 | static int sh_wdt_open(struct inode *inode, struct file *file) | |
196 | { | |
197 | if (test_and_set_bit(0, &shwdt_is_open)) | |
198 | return -EBUSY; | |
199 | if (nowayout) | |
200 | __module_get(THIS_MODULE); | |
201 | ||
202 | sh_wdt_start(); | |
203 | ||
204 | return nonseekable_open(inode, file); | |
205 | } | |
206 | ||
207 | /** | |
208 | * sh_wdt_close - Close the Device | |
1da177e4 LT |
209 | * @inode: inode of device |
210 | * @file: file handle of device | |
211 | * | |
212 | * Watchdog device is closed and stopped. | |
213 | */ | |
214 | static int sh_wdt_close(struct inode *inode, struct file *file) | |
215 | { | |
216 | if (shwdt_expect_close == 42) { | |
217 | sh_wdt_stop(); | |
218 | } else { | |
e4c2cfee PM |
219 | printk(KERN_CRIT PFX "Unexpected close, not " |
220 | "stopping watchdog!\n"); | |
1da177e4 LT |
221 | sh_wdt_keepalive(); |
222 | } | |
223 | ||
224 | clear_bit(0, &shwdt_is_open); | |
225 | shwdt_expect_close = 0; | |
226 | ||
227 | return 0; | |
228 | } | |
229 | ||
230 | /** | |
231 | * sh_wdt_write - Write to Device | |
1da177e4 LT |
232 | * @file: file handle of device |
233 | * @buf: buffer to write | |
234 | * @count: length of buffer | |
235 | * @ppos: offset | |
236 | * | |
237 | * Pings the watchdog on write. | |
238 | */ | |
239 | static ssize_t sh_wdt_write(struct file *file, const char *buf, | |
240 | size_t count, loff_t *ppos) | |
241 | { | |
242 | if (count) { | |
243 | if (!nowayout) { | |
244 | size_t i; | |
245 | ||
246 | shwdt_expect_close = 0; | |
247 | ||
248 | for (i = 0; i != count; i++) { | |
249 | char c; | |
250 | if (get_user(c, buf + i)) | |
251 | return -EFAULT; | |
252 | if (c == 'V') | |
253 | shwdt_expect_close = 42; | |
254 | } | |
255 | } | |
256 | sh_wdt_keepalive(); | |
257 | } | |
258 | ||
259 | return count; | |
260 | } | |
261 | ||
f118420b PM |
262 | /** |
263 | * sh_wdt_mmap - map WDT/CPG registers into userspace | |
264 | * @file: file structure for the device | |
265 | * @vma: VMA to map the registers into | |
266 | * | |
267 | * A simple mmap() implementation for the corner cases where the counter | |
268 | * needs to be mapped in userspace directly. Due to the relatively small | |
269 | * size of the area, neighbouring registers not necessarily tied to the | |
270 | * CPG will also be accessible through the register page, so this remains | |
271 | * configurable for users that really know what they're doing. | |
272 | * | |
273 | * Additionaly, the register page maps in the CPG register base relative | |
274 | * to the nearest page-aligned boundary, which requires that userspace do | |
275 | * the appropriate CPU subtype math for calculating the page offset for | |
276 | * the counter value. | |
277 | */ | |
278 | static int sh_wdt_mmap(struct file *file, struct vm_area_struct *vma) | |
279 | { | |
280 | int ret = -ENOSYS; | |
281 | ||
282 | #ifdef CONFIG_SH_WDT_MMAP | |
283 | unsigned long addr; | |
284 | ||
285 | /* Only support the simple cases where we map in a register page. */ | |
286 | if (((vma->vm_end - vma->vm_start) != PAGE_SIZE) || vma->vm_pgoff) | |
287 | return -EINVAL; | |
288 | ||
289 | /* | |
290 | * Pick WTCNT as the start, it's usually the first register after the | |
291 | * FRQCR, and neither one are generally page-aligned out of the box. | |
292 | */ | |
293 | addr = WTCNT & ~(PAGE_SIZE - 1); | |
294 | ||
295 | vma->vm_flags |= VM_IO; | |
296 | vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); | |
297 | ||
298 | if (io_remap_pfn_range(vma, vma->vm_start, addr >> PAGE_SHIFT, | |
299 | PAGE_SIZE, vma->vm_page_prot)) { | |
300 | printk(KERN_ERR PFX "%s: io_remap_pfn_range failed\n", | |
301 | __FUNCTION__); | |
302 | return -EAGAIN; | |
303 | } | |
304 | ||
305 | ret = 0; | |
306 | #endif | |
307 | ||
308 | return ret; | |
309 | } | |
310 | ||
1da177e4 LT |
311 | /** |
312 | * sh_wdt_ioctl - Query Device | |
1da177e4 LT |
313 | * @inode: inode of device |
314 | * @file: file handle of device | |
315 | * @cmd: watchdog command | |
316 | * @arg: argument | |
317 | * | |
318 | * Query basic information from the device or ping it, as outlined by the | |
319 | * watchdog API. | |
320 | */ | |
321 | static int sh_wdt_ioctl(struct inode *inode, struct file *file, | |
322 | unsigned int cmd, unsigned long arg) | |
323 | { | |
324 | int new_heartbeat; | |
325 | int options, retval = -EINVAL; | |
326 | ||
327 | switch (cmd) { | |
328 | case WDIOC_GETSUPPORT: | |
329 | return copy_to_user((struct watchdog_info *)arg, | |
330 | &sh_wdt_info, | |
331 | sizeof(sh_wdt_info)) ? -EFAULT : 0; | |
332 | case WDIOC_GETSTATUS: | |
333 | case WDIOC_GETBOOTSTATUS: | |
334 | return put_user(0, (int *)arg); | |
335 | case WDIOC_KEEPALIVE: | |
336 | sh_wdt_keepalive(); | |
337 | return 0; | |
338 | case WDIOC_SETTIMEOUT: | |
339 | if (get_user(new_heartbeat, (int *)arg)) | |
340 | return -EFAULT; | |
341 | ||
342 | if (sh_wdt_set_heartbeat(new_heartbeat)) | |
343 | return -EINVAL; | |
344 | ||
345 | sh_wdt_keepalive(); | |
346 | /* Fall */ | |
347 | case WDIOC_GETTIMEOUT: | |
348 | return put_user(heartbeat, (int *)arg); | |
349 | case WDIOC_SETOPTIONS: | |
350 | if (get_user(options, (int *)arg)) | |
351 | return -EFAULT; | |
352 | ||
353 | if (options & WDIOS_DISABLECARD) { | |
354 | sh_wdt_stop(); | |
355 | retval = 0; | |
356 | } | |
357 | ||
358 | if (options & WDIOS_ENABLECARD) { | |
359 | sh_wdt_start(); | |
360 | retval = 0; | |
361 | } | |
362 | ||
363 | return retval; | |
364 | default: | |
795b89d2 | 365 | return -ENOTTY; |
1da177e4 LT |
366 | } |
367 | ||
368 | return 0; | |
369 | } | |
370 | ||
371 | /** | |
372 | * sh_wdt_notify_sys - Notifier Handler | |
1da177e4 LT |
373 | * @this: notifier block |
374 | * @code: notifier event | |
375 | * @unused: unused | |
376 | * | |
377 | * Handles specific events, such as turning off the watchdog during a | |
378 | * shutdown event. | |
379 | */ | |
380 | static int sh_wdt_notify_sys(struct notifier_block *this, | |
381 | unsigned long code, void *unused) | |
382 | { | |
e4c2cfee | 383 | if (code == SYS_DOWN || code == SYS_HALT) |
1da177e4 | 384 | sh_wdt_stop(); |
1da177e4 LT |
385 | |
386 | return NOTIFY_DONE; | |
387 | } | |
388 | ||
62322d25 | 389 | static const struct file_operations sh_wdt_fops = { |
1da177e4 LT |
390 | .owner = THIS_MODULE, |
391 | .llseek = no_llseek, | |
392 | .write = sh_wdt_write, | |
393 | .ioctl = sh_wdt_ioctl, | |
394 | .open = sh_wdt_open, | |
395 | .release = sh_wdt_close, | |
f118420b | 396 | .mmap = sh_wdt_mmap, |
1da177e4 LT |
397 | }; |
398 | ||
399 | static struct watchdog_info sh_wdt_info = { | |
e4c2cfee PM |
400 | .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | |
401 | WDIOF_MAGICCLOSE, | |
1da177e4 LT |
402 | .firmware_version = 1, |
403 | .identity = "SH WDT", | |
404 | }; | |
405 | ||
406 | static struct notifier_block sh_wdt_notifier = { | |
407 | .notifier_call = sh_wdt_notify_sys, | |
408 | }; | |
409 | ||
410 | static struct miscdevice sh_wdt_miscdev = { | |
411 | .minor = WATCHDOG_MINOR, | |
412 | .name = "watchdog", | |
413 | .fops = &sh_wdt_fops, | |
414 | }; | |
415 | ||
416 | /** | |
417 | * sh_wdt_init - Initialize module | |
1da177e4 LT |
418 | * Registers the device and notifier handler. Actual device |
419 | * initialization is handled by sh_wdt_open(). | |
420 | */ | |
421 | static int __init sh_wdt_init(void) | |
422 | { | |
423 | int rc; | |
424 | ||
425 | if ((clock_division_ratio < 0x5) || (clock_division_ratio > 0x7)) { | |
426 | clock_division_ratio = WTCSR_CKS_4096; | |
e4c2cfee PM |
427 | printk(KERN_INFO PFX "clock_division_ratio value must " |
428 | "be 0x5<=x<=0x7, using %d\n", clock_division_ratio); | |
1da177e4 LT |
429 | } |
430 | ||
e4c2cfee PM |
431 | rc = sh_wdt_set_heartbeat(heartbeat); |
432 | if (unlikely(rc)) { | |
1da177e4 | 433 | heartbeat = WATCHDOG_HEARTBEAT; |
e4c2cfee PM |
434 | printk(KERN_INFO PFX "heartbeat value must " |
435 | "be 1<=x<=3600, using %d\n", heartbeat); | |
1da177e4 LT |
436 | } |
437 | ||
1da177e4 | 438 | rc = register_reboot_notifier(&sh_wdt_notifier); |
e4c2cfee PM |
439 | if (unlikely(rc)) { |
440 | printk(KERN_ERR PFX "Can't register reboot notifier (err=%d)\n", | |
441 | rc); | |
1da177e4 LT |
442 | return rc; |
443 | } | |
444 | ||
445 | rc = misc_register(&sh_wdt_miscdev); | |
e4c2cfee PM |
446 | if (unlikely(rc)) { |
447 | printk(KERN_ERR PFX "Can't register miscdev on " | |
448 | "minor=%d (err=%d)\n", sh_wdt_miscdev.minor, rc); | |
1da177e4 LT |
449 | unregister_reboot_notifier(&sh_wdt_notifier); |
450 | return rc; | |
451 | } | |
452 | ||
453 | printk(KERN_INFO PFX "initialized. heartbeat=%d sec (nowayout=%d)\n", | |
454 | heartbeat, nowayout); | |
455 | ||
456 | return 0; | |
457 | } | |
458 | ||
459 | /** | |
460 | * sh_wdt_exit - Deinitialize module | |
1da177e4 LT |
461 | * Unregisters the device and notifier handler. Actual device |
462 | * deinitialization is handled by sh_wdt_close(). | |
463 | */ | |
464 | static void __exit sh_wdt_exit(void) | |
465 | { | |
466 | misc_deregister(&sh_wdt_miscdev); | |
467 | unregister_reboot_notifier(&sh_wdt_notifier); | |
468 | } | |
469 | ||
470 | MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>"); | |
471 | MODULE_DESCRIPTION("SuperH watchdog driver"); | |
472 | MODULE_LICENSE("GPL"); | |
473 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); | |
474 | ||
475 | module_param(clock_division_ratio, int, 0); | |
e4c2cfee | 476 | 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 |
477 | |
478 | module_param(heartbeat, int, 0); | |
479 | MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (1<=heartbeat<=3600, default=" __MODULE_STRING(WATCHDOG_HEARTBEAT) ")"); | |
480 | ||
481 | module_param(nowayout, int, 0); | |
e4c2cfee | 482 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
1da177e4 LT |
483 | |
484 | module_init(sh_wdt_init); | |
485 | module_exit(sh_wdt_exit); |