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1e6d320f BW |
1 | /* |
2 | * Blackfin On-Chip Watchdog Driver | |
3 | * Supports BF53[123]/BF53[467]/BF54[2489]/BF561 | |
4 | * | |
5 | * Originally based on softdog.c | |
6 | * Copyright 2006-2007 Analog Devices Inc. | |
7 | * Copyright 2006-2007 Michele d'Amico | |
8 | * Copyright 1996 Alan Cox <alan@redhat.com> | |
9 | * | |
10 | * Enter bugs at http://blackfin.uclinux.org/ | |
11 | * | |
12 | * Licensed under the GPL-2 or later. | |
13 | */ | |
14 | ||
15 | #include <linux/platform_device.h> | |
16 | #include <linux/module.h> | |
17 | #include <linux/moduleparam.h> | |
18 | #include <linux/types.h> | |
19 | #include <linux/timer.h> | |
20 | #include <linux/miscdevice.h> | |
21 | #include <linux/watchdog.h> | |
22 | #include <linux/fs.h> | |
23 | #include <linux/notifier.h> | |
24 | #include <linux/reboot.h> | |
25 | #include <linux/init.h> | |
26 | #include <linux/interrupt.h> | |
27 | #include <asm/blackfin.h> | |
28 | #include <asm/uaccess.h> | |
29 | ||
30 | #define stamp(fmt, args...) pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args) | |
31 | #define stampit() stamp("here i am") | |
32 | ||
33 | #define WATCHDOG_NAME "bfin-wdt" | |
34 | #define PFX WATCHDOG_NAME ": " | |
35 | ||
36 | /* The BF561 has two watchdogs (one per core), but since Linux | |
37 | * only runs on core A, we'll just work with that one. | |
38 | */ | |
39 | #ifdef BF561_FAMILY | |
40 | # define bfin_read_WDOG_CTL() bfin_read_WDOGA_CTL() | |
41 | # define bfin_read_WDOG_CNT() bfin_read_WDOGA_CNT() | |
42 | # define bfin_read_WDOG_STAT() bfin_read_WDOGA_STAT() | |
43 | # define bfin_write_WDOG_CTL(x) bfin_write_WDOGA_CTL(x) | |
44 | # define bfin_write_WDOG_CNT(x) bfin_write_WDOGA_CNT(x) | |
45 | # define bfin_write_WDOG_STAT(x) bfin_write_WDOGA_STAT(x) | |
46 | #endif | |
47 | ||
48 | /* Bit in SWRST that indicates boot caused by watchdog */ | |
49 | #define SWRST_RESET_WDOG 0x4000 | |
50 | ||
51 | /* Bit in WDOG_CTL that indicates watchdog has expired (WDR0) */ | |
52 | #define WDOG_EXPIRED 0x8000 | |
53 | ||
54 | /* Masks for WDEV field in WDOG_CTL register */ | |
55 | #define ICTL_RESET 0x0 | |
56 | #define ICTL_NMI 0x2 | |
57 | #define ICTL_GPI 0x4 | |
58 | #define ICTL_NONE 0x6 | |
59 | #define ICTL_MASK 0x6 | |
60 | ||
61 | /* Masks for WDEN field in WDOG_CTL register */ | |
62 | #define WDEN_MASK 0x0FF0 | |
63 | #define WDEN_ENABLE 0x0000 | |
64 | #define WDEN_DISABLE 0x0AD0 | |
65 | ||
66 | /* some defaults */ | |
67 | #define WATCHDOG_TIMEOUT 20 | |
68 | ||
69 | static unsigned int timeout = WATCHDOG_TIMEOUT; | |
70 | static int nowayout = WATCHDOG_NOWAYOUT; | |
71 | static struct watchdog_info bfin_wdt_info; | |
72 | static unsigned long open_check; | |
73 | static char expect_close; | |
bf6350a3 | 74 | static DEFINE_SPINLOCK(bfin_wdt_spinlock); |
1e6d320f BW |
75 | |
76 | /** | |
77 | * bfin_wdt_keepalive - Keep the Userspace Watchdog Alive | |
78 | * | |
79 | * The Userspace watchdog got a KeepAlive: schedule the next timeout. | |
80 | */ | |
81 | static int bfin_wdt_keepalive(void) | |
82 | { | |
83 | stampit(); | |
84 | bfin_write_WDOG_STAT(0); | |
85 | return 0; | |
86 | } | |
87 | ||
88 | /** | |
89 | * bfin_wdt_stop - Stop the Watchdog | |
90 | * | |
91 | * Stops the on-chip watchdog. | |
92 | */ | |
93 | static int bfin_wdt_stop(void) | |
94 | { | |
95 | stampit(); | |
96 | bfin_write_WDOG_CTL(WDEN_DISABLE); | |
97 | return 0; | |
98 | } | |
99 | ||
100 | /** | |
101 | * bfin_wdt_start - Start the Watchdog | |
102 | * | |
103 | * Starts the on-chip watchdog. Automatically loads WDOG_CNT | |
104 | * into WDOG_STAT for us. | |
105 | */ | |
106 | static int bfin_wdt_start(void) | |
107 | { | |
108 | stampit(); | |
109 | bfin_write_WDOG_CTL(WDEN_ENABLE | ICTL_RESET); | |
110 | return 0; | |
111 | } | |
112 | ||
113 | /** | |
114 | * bfin_wdt_running - Check Watchdog status | |
115 | * | |
116 | * See if the watchdog is running. | |
117 | */ | |
118 | static int bfin_wdt_running(void) | |
119 | { | |
120 | stampit(); | |
121 | return ((bfin_read_WDOG_CTL() & WDEN_MASK) != WDEN_DISABLE); | |
122 | } | |
123 | ||
124 | /** | |
125 | * bfin_wdt_set_timeout - Set the Userspace Watchdog timeout | |
126 | * @t: new timeout value (in seconds) | |
127 | * | |
128 | * Translate the specified timeout in seconds into System Clock | |
129 | * terms which is what the on-chip Watchdog requires. | |
130 | */ | |
131 | static int bfin_wdt_set_timeout(unsigned long t) | |
132 | { | |
133 | u32 cnt; | |
134 | unsigned long flags; | |
135 | ||
136 | stampit(); | |
137 | ||
138 | cnt = t * get_sclk(); | |
139 | if (cnt < get_sclk()) { | |
140 | printk(KERN_WARNING PFX "timeout value is too large\n"); | |
141 | return -EINVAL; | |
142 | } | |
143 | ||
144 | spin_lock_irqsave(&bfin_wdt_spinlock, flags); | |
145 | { | |
146 | int run = bfin_wdt_running(); | |
147 | bfin_wdt_stop(); | |
148 | bfin_write_WDOG_CNT(cnt); | |
149 | if (run) bfin_wdt_start(); | |
150 | } | |
151 | spin_unlock_irqrestore(&bfin_wdt_spinlock, flags); | |
152 | ||
153 | timeout = t; | |
154 | ||
155 | return 0; | |
156 | } | |
157 | ||
158 | /** | |
159 | * bfin_wdt_open - Open the Device | |
160 | * @inode: inode of device | |
161 | * @file: file handle of device | |
162 | * | |
163 | * Watchdog device is opened and started. | |
164 | */ | |
165 | static int bfin_wdt_open(struct inode *inode, struct file *file) | |
166 | { | |
167 | stampit(); | |
168 | ||
169 | if (test_and_set_bit(0, &open_check)) | |
170 | return -EBUSY; | |
171 | ||
172 | if (nowayout) | |
173 | __module_get(THIS_MODULE); | |
174 | ||
175 | bfin_wdt_keepalive(); | |
176 | bfin_wdt_start(); | |
177 | ||
178 | return nonseekable_open(inode, file); | |
179 | } | |
180 | ||
181 | /** | |
182 | * bfin_wdt_close - Close the Device | |
183 | * @inode: inode of device | |
184 | * @file: file handle of device | |
185 | * | |
186 | * Watchdog device is closed and stopped. | |
187 | */ | |
188 | static int bfin_wdt_release(struct inode *inode, struct file *file) | |
189 | { | |
190 | stampit(); | |
191 | ||
192 | if (expect_close == 42) { | |
193 | bfin_wdt_stop(); | |
194 | } else { | |
195 | printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n"); | |
196 | bfin_wdt_keepalive(); | |
197 | } | |
198 | ||
199 | expect_close = 0; | |
200 | clear_bit(0, &open_check); | |
201 | ||
202 | return 0; | |
203 | } | |
204 | ||
205 | /** | |
206 | * bfin_wdt_write - Write to Device | |
207 | * @file: file handle of device | |
208 | * @buf: buffer to write | |
209 | * @count: length of buffer | |
210 | * @ppos: offset | |
211 | * | |
212 | * Pings the watchdog on write. | |
213 | */ | |
214 | static ssize_t bfin_wdt_write(struct file *file, const char __user *data, | |
215 | size_t len, loff_t *ppos) | |
216 | { | |
217 | stampit(); | |
218 | ||
219 | if (len) { | |
220 | if (!nowayout) { | |
221 | size_t i; | |
222 | ||
223 | /* In case it was set long ago */ | |
224 | expect_close = 0; | |
225 | ||
226 | for (i = 0; i != len; i++) { | |
227 | char c; | |
228 | if (get_user(c, data + i)) | |
229 | return -EFAULT; | |
230 | if (c == 'V') | |
231 | expect_close = 42; | |
232 | } | |
233 | } | |
234 | bfin_wdt_keepalive(); | |
235 | } | |
236 | ||
237 | return len; | |
238 | } | |
239 | ||
240 | /** | |
241 | * bfin_wdt_ioctl - Query Device | |
242 | * @inode: inode of device | |
243 | * @file: file handle of device | |
244 | * @cmd: watchdog command | |
245 | * @arg: argument | |
246 | * | |
247 | * Query basic information from the device or ping it, as outlined by the | |
248 | * watchdog API. | |
249 | */ | |
250 | static int bfin_wdt_ioctl(struct inode *inode, struct file *file, | |
251 | unsigned int cmd, unsigned long arg) | |
252 | { | |
253 | void __user *argp = (void __user *)arg; | |
254 | int __user *p = argp; | |
255 | ||
256 | stampit(); | |
257 | ||
258 | switch (cmd) { | |
259 | default: | |
260 | return -ENOTTY; | |
261 | ||
262 | case WDIOC_GETSUPPORT: | |
263 | if (copy_to_user(argp, &bfin_wdt_info, sizeof(bfin_wdt_info))) | |
264 | return -EFAULT; | |
265 | else | |
266 | return 0; | |
267 | ||
268 | case WDIOC_GETSTATUS: | |
269 | case WDIOC_GETBOOTSTATUS: | |
270 | return put_user(!!(_bfin_swrst & SWRST_RESET_WDOG), p); | |
271 | ||
272 | case WDIOC_KEEPALIVE: | |
273 | bfin_wdt_keepalive(); | |
274 | return 0; | |
275 | ||
276 | case WDIOC_SETTIMEOUT: { | |
277 | int new_timeout; | |
278 | ||
279 | if (get_user(new_timeout, p)) | |
280 | return -EFAULT; | |
281 | ||
282 | if (bfin_wdt_set_timeout(new_timeout)) | |
283 | return -EINVAL; | |
284 | } | |
285 | /* Fall */ | |
286 | case WDIOC_GETTIMEOUT: | |
287 | return put_user(timeout, p); | |
288 | ||
289 | case WDIOC_SETOPTIONS: { | |
290 | unsigned long flags; | |
291 | int options, ret = -EINVAL; | |
292 | ||
293 | if (get_user(options, p)) | |
294 | return -EFAULT; | |
295 | ||
296 | spin_lock_irqsave(&bfin_wdt_spinlock, flags); | |
297 | ||
298 | if (options & WDIOS_DISABLECARD) { | |
299 | bfin_wdt_stop(); | |
300 | ret = 0; | |
301 | } | |
302 | ||
303 | if (options & WDIOS_ENABLECARD) { | |
304 | bfin_wdt_start(); | |
305 | ret = 0; | |
306 | } | |
307 | ||
308 | spin_unlock_irqrestore(&bfin_wdt_spinlock, flags); | |
309 | ||
310 | return ret; | |
311 | } | |
312 | } | |
313 | } | |
314 | ||
315 | /** | |
316 | * bfin_wdt_notify_sys - Notifier Handler | |
317 | * @this: notifier block | |
318 | * @code: notifier event | |
319 | * @unused: unused | |
320 | * | |
321 | * Handles specific events, such as turning off the watchdog during a | |
322 | * shutdown event. | |
323 | */ | |
324 | static int bfin_wdt_notify_sys(struct notifier_block *this, unsigned long code, | |
325 | void *unused) | |
326 | { | |
327 | stampit(); | |
328 | ||
329 | if (code == SYS_DOWN || code == SYS_HALT) | |
330 | bfin_wdt_stop(); | |
331 | ||
332 | return NOTIFY_DONE; | |
333 | } | |
334 | ||
335 | #ifdef CONFIG_PM | |
336 | static int state_before_suspend; | |
337 | ||
338 | /** | |
339 | * bfin_wdt_suspend - suspend the watchdog | |
340 | * @pdev: device being suspended | |
341 | * @state: requested suspend state | |
342 | * | |
343 | * Remember if the watchdog was running and stop it. | |
344 | * TODO: is this even right? Doesn't seem to be any | |
345 | * standard in the watchdog world ... | |
346 | */ | |
347 | static int bfin_wdt_suspend(struct platform_device *pdev, pm_message_t state) | |
348 | { | |
349 | stampit(); | |
350 | ||
351 | state_before_suspend = bfin_wdt_running(); | |
352 | bfin_wdt_stop(); | |
353 | ||
354 | return 0; | |
355 | } | |
356 | ||
357 | /** | |
358 | * bfin_wdt_resume - resume the watchdog | |
359 | * @pdev: device being resumed | |
360 | * | |
361 | * If the watchdog was running, turn it back on. | |
362 | */ | |
363 | static int bfin_wdt_resume(struct platform_device *pdev) | |
364 | { | |
365 | stampit(); | |
366 | ||
367 | if (state_before_suspend) { | |
368 | bfin_wdt_set_timeout(timeout); | |
369 | bfin_wdt_start(); | |
370 | } | |
371 | ||
372 | return 0; | |
373 | } | |
374 | #else | |
375 | # define bfin_wdt_suspend NULL | |
376 | # define bfin_wdt_resume NULL | |
377 | #endif | |
378 | ||
379 | static struct platform_device bfin_wdt_device = { | |
380 | .name = WATCHDOG_NAME, | |
381 | .id = -1, | |
382 | }; | |
383 | ||
384 | static struct platform_driver bfin_wdt_driver = { | |
385 | .driver = { | |
386 | .name = WATCHDOG_NAME, | |
387 | .owner = THIS_MODULE, | |
388 | }, | |
389 | .suspend = bfin_wdt_suspend, | |
390 | .resume = bfin_wdt_resume, | |
391 | }; | |
392 | ||
b47a166e | 393 | static const struct file_operations bfin_wdt_fops = { |
1e6d320f BW |
394 | .owner = THIS_MODULE, |
395 | .llseek = no_llseek, | |
396 | .write = bfin_wdt_write, | |
397 | .ioctl = bfin_wdt_ioctl, | |
398 | .open = bfin_wdt_open, | |
399 | .release = bfin_wdt_release, | |
400 | }; | |
401 | ||
402 | static struct miscdevice bfin_wdt_miscdev = { | |
403 | .minor = WATCHDOG_MINOR, | |
404 | .name = "watchdog", | |
405 | .fops = &bfin_wdt_fops, | |
406 | }; | |
407 | ||
408 | static struct watchdog_info bfin_wdt_info = { | |
409 | .identity = "Blackfin Watchdog", | |
410 | .options = WDIOF_SETTIMEOUT | | |
411 | WDIOF_KEEPALIVEPING | | |
412 | WDIOF_MAGICCLOSE, | |
413 | }; | |
414 | ||
415 | static struct notifier_block bfin_wdt_notifier = { | |
416 | .notifier_call = bfin_wdt_notify_sys, | |
417 | }; | |
418 | ||
419 | /** | |
420 | * bfin_wdt_init - Initialize module | |
421 | * | |
422 | * Registers the device and notifier handler. Actual device | |
423 | * initialization is handled by bfin_wdt_open(). | |
424 | */ | |
425 | static int __init bfin_wdt_init(void) | |
426 | { | |
427 | int ret; | |
428 | ||
429 | stampit(); | |
430 | ||
431 | /* Check that the timeout value is within range */ | |
432 | if (bfin_wdt_set_timeout(timeout)) | |
433 | return -EINVAL; | |
434 | ||
435 | /* Since this is an on-chip device and needs no board-specific | |
436 | * resources, we'll handle all the platform device stuff here. | |
437 | */ | |
438 | ret = platform_device_register(&bfin_wdt_device); | |
439 | if (ret) | |
440 | return ret; | |
441 | ||
442 | ret = platform_driver_probe(&bfin_wdt_driver, NULL); | |
443 | if (ret) | |
444 | return ret; | |
445 | ||
446 | ret = register_reboot_notifier(&bfin_wdt_notifier); | |
447 | if (ret) { | |
448 | printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n", ret); | |
449 | return ret; | |
450 | } | |
451 | ||
452 | ret = misc_register(&bfin_wdt_miscdev); | |
453 | if (ret) { | |
454 | printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n", | |
455 | WATCHDOG_MINOR, ret); | |
456 | unregister_reboot_notifier(&bfin_wdt_notifier); | |
457 | return ret; | |
458 | } | |
459 | ||
460 | printk(KERN_INFO PFX "initialized: timeout=%d sec (nowayout=%d)\n", | |
461 | timeout, nowayout); | |
462 | ||
463 | return 0; | |
464 | } | |
465 | ||
466 | /** | |
467 | * bfin_wdt_exit - Deinitialize module | |
468 | * | |
469 | * Unregisters the device and notifier handler. Actual device | |
470 | * deinitialization is handled by bfin_wdt_close(). | |
471 | */ | |
472 | static void __exit bfin_wdt_exit(void) | |
473 | { | |
474 | misc_deregister(&bfin_wdt_miscdev); | |
475 | unregister_reboot_notifier(&bfin_wdt_notifier); | |
476 | } | |
477 | ||
478 | module_init(bfin_wdt_init); | |
479 | module_exit(bfin_wdt_exit); | |
480 | ||
481 | MODULE_AUTHOR("Michele d'Amico, Mike Frysinger <vapier@gentoo.org>"); | |
482 | MODULE_DESCRIPTION("Blackfin Watchdog Device Driver"); | |
483 | MODULE_LICENSE("GPL"); | |
484 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); | |
485 | ||
486 | module_param(timeout, uint, 0); | |
487 | MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=((2^32)/SCLK), default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); | |
488 | ||
489 | module_param(nowayout, int, 0); | |
490 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |