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1 | /* |
2 | * Blackfin On-Chip Watchdog Driver |
3 | * |
4 | * Originally based on softdog.c |
5 | * Copyright 2006-2010 Analog Devices Inc. |
6 | * Copyright 2006-2007 Michele d'Amico |
7 | * Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk> |
8 | * |
9 | * Enter bugs at http://blackfin.uclinux.org/ |
10 | * |
11 | * Licensed under the GPL-2 or later. |
12 | */ |
13 | |
14 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
15 | |
16 | #include <linux/platform_device.h> |
17 | #include <linux/module.h> |
18 | #include <linux/moduleparam.h> |
19 | #include <linux/types.h> |
20 | #include <linux/timer.h> |
21 | #include <linux/miscdevice.h> |
22 | #include <linux/watchdog.h> |
23 | #include <linux/fs.h> |
24 | #include <linux/init.h> |
25 | #include <linux/interrupt.h> |
26 | #include <linux/uaccess.h> |
27 | #include <asm/blackfin.h> |
28 | #include <asm/bfin_watchdog.h> |
29 | |
30 | #define stamp(fmt, args...) \ |
31 | pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args) |
32 | #define stampit() stamp("here i am") |
33 | |
34 | #define WATCHDOG_NAME "bfin-wdt" |
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 | /* some defaults */ |
49 | #define WATCHDOG_TIMEOUT 20 |
50 | |
51 | static unsigned int timeout = WATCHDOG_TIMEOUT; |
52 | static bool nowayout = WATCHDOG_NOWAYOUT; |
53 | static const struct watchdog_info bfin_wdt_info; |
54 | static unsigned long open_check; |
55 | static char expect_close; |
56 | static DEFINE_SPINLOCK(bfin_wdt_spinlock); |
57 | |
58 | /** |
59 | * bfin_wdt_keepalive - Keep the Userspace Watchdog Alive |
60 | * |
61 | * The Userspace watchdog got a KeepAlive: schedule the next timeout. |
62 | */ |
63 | static int bfin_wdt_keepalive(void) |
64 | { |
65 | stampit(); |
66 | bfin_write_WDOG_STAT(0); |
67 | return 0; |
68 | } |
69 | |
70 | /** |
71 | * bfin_wdt_stop - Stop the Watchdog |
72 | * |
73 | * Stops the on-chip watchdog. |
74 | */ |
75 | static int bfin_wdt_stop(void) |
76 | { |
77 | stampit(); |
78 | bfin_write_WDOG_CTL(WDEN_DISABLE); |
79 | return 0; |
80 | } |
81 | |
82 | /** |
83 | * bfin_wdt_start - Start the Watchdog |
84 | * |
85 | * Starts the on-chip watchdog. Automatically loads WDOG_CNT |
86 | * into WDOG_STAT for us. |
87 | */ |
88 | static int bfin_wdt_start(void) |
89 | { |
90 | stampit(); |
91 | bfin_write_WDOG_CTL(WDEN_ENABLE | ICTL_RESET); |
92 | return 0; |
93 | } |
94 | |
95 | /** |
96 | * bfin_wdt_running - Check Watchdog status |
97 | * |
98 | * See if the watchdog is running. |
99 | */ |
100 | static int bfin_wdt_running(void) |
101 | { |
102 | stampit(); |
103 | return ((bfin_read_WDOG_CTL() & WDEN_MASK) != WDEN_DISABLE); |
104 | } |
105 | |
106 | /** |
107 | * bfin_wdt_set_timeout - Set the Userspace Watchdog timeout |
108 | * @t: new timeout value (in seconds) |
109 | * |
110 | * Translate the specified timeout in seconds into System Clock |
111 | * terms which is what the on-chip Watchdog requires. |
112 | */ |
113 | static int bfin_wdt_set_timeout(unsigned long t) |
114 | { |
115 | u32 cnt, max_t, sclk; |
116 | unsigned long flags; |
117 | |
118 | sclk = get_sclk(); |
119 | max_t = -1 / sclk; |
120 | cnt = t * sclk; |
121 | stamp("maxtimeout=%us newtimeout=%lus (cnt=%#x)", max_t, t, cnt); |
122 | |
123 | if (t > max_t) { |
124 | pr_warn("timeout value is too large\n"); |
125 | return -EINVAL; |
126 | } |
127 | |
128 | spin_lock_irqsave(&bfin_wdt_spinlock, flags); |
129 | { |
130 | int run = bfin_wdt_running(); |
131 | bfin_wdt_stop(); |
132 | bfin_write_WDOG_CNT(cnt); |
133 | if (run) |
134 | bfin_wdt_start(); |
135 | } |
136 | spin_unlock_irqrestore(&bfin_wdt_spinlock, flags); |
137 | |
138 | timeout = t; |
139 | |
140 | return 0; |
141 | } |
142 | |
143 | /** |
144 | * bfin_wdt_open - Open the Device |
145 | * @inode: inode of device |
146 | * @file: file handle of device |
147 | * |
148 | * Watchdog device is opened and started. |
149 | */ |
150 | static int bfin_wdt_open(struct inode *inode, struct file *file) |
151 | { |
152 | stampit(); |
153 | |
154 | if (test_and_set_bit(0, &open_check)) |
155 | return -EBUSY; |
156 | |
157 | if (nowayout) |
158 | __module_get(THIS_MODULE); |
159 | |
160 | bfin_wdt_keepalive(); |
161 | bfin_wdt_start(); |
162 | |
163 | return nonseekable_open(inode, file); |
164 | } |
165 | |
166 | /** |
167 | * bfin_wdt_close - Close the Device |
168 | * @inode: inode of device |
169 | * @file: file handle of device |
170 | * |
171 | * Watchdog device is closed and stopped. |
172 | */ |
173 | static int bfin_wdt_release(struct inode *inode, struct file *file) |
174 | { |
175 | stampit(); |
176 | |
177 | if (expect_close == 42) |
178 | bfin_wdt_stop(); |
179 | else { |
180 | pr_crit("Unexpected close, not stopping watchdog!\n"); |
181 | bfin_wdt_keepalive(); |
182 | } |
183 | expect_close = 0; |
184 | clear_bit(0, &open_check); |
185 | return 0; |
186 | } |
187 | |
188 | /** |
189 | * bfin_wdt_write - Write to Device |
190 | * @file: file handle of device |
191 | * @buf: buffer to write |
192 | * @count: length of buffer |
193 | * @ppos: offset |
194 | * |
195 | * Pings the watchdog on write. |
196 | */ |
197 | static ssize_t bfin_wdt_write(struct file *file, const char __user *data, |
198 | size_t len, loff_t *ppos) |
199 | { |
200 | stampit(); |
201 | |
202 | if (len) { |
203 | if (!nowayout) { |
204 | size_t i; |
205 | |
206 | /* In case it was set long ago */ |
207 | expect_close = 0; |
208 | |
209 | for (i = 0; i != len; i++) { |
210 | char c; |
211 | if (get_user(c, data + i)) |
212 | return -EFAULT; |
213 | if (c == 'V') |
214 | expect_close = 42; |
215 | } |
216 | } |
217 | bfin_wdt_keepalive(); |
218 | } |
219 | |
220 | return len; |
221 | } |
222 | |
223 | /** |
224 | * bfin_wdt_ioctl - Query Device |
225 | * @file: file handle of device |
226 | * @cmd: watchdog command |
227 | * @arg: argument |
228 | * |
229 | * Query basic information from the device or ping it, as outlined by the |
230 | * watchdog API. |
231 | */ |
232 | static long bfin_wdt_ioctl(struct file *file, |
233 | unsigned int cmd, unsigned long arg) |
234 | { |
235 | void __user *argp = (void __user *)arg; |
236 | int __user *p = argp; |
237 | |
238 | stampit(); |
239 | |
240 | switch (cmd) { |
241 | case WDIOC_GETSUPPORT: |
242 | if (copy_to_user(argp, &bfin_wdt_info, sizeof(bfin_wdt_info))) |
243 | return -EFAULT; |
244 | else |
245 | return 0; |
246 | case WDIOC_GETSTATUS: |
247 | case WDIOC_GETBOOTSTATUS: |
248 | return put_user(!!(_bfin_swrst & SWRST_RESET_WDOG), p); |
249 | case WDIOC_SETOPTIONS: { |
250 | unsigned long flags; |
251 | int options, ret = -EINVAL; |
252 | |
253 | if (get_user(options, p)) |
254 | return -EFAULT; |
255 | |
256 | spin_lock_irqsave(&bfin_wdt_spinlock, flags); |
257 | if (options & WDIOS_DISABLECARD) { |
258 | bfin_wdt_stop(); |
259 | ret = 0; |
260 | } |
261 | if (options & WDIOS_ENABLECARD) { |
262 | bfin_wdt_start(); |
263 | ret = 0; |
264 | } |
265 | spin_unlock_irqrestore(&bfin_wdt_spinlock, flags); |
266 | return ret; |
267 | } |
268 | case WDIOC_KEEPALIVE: |
269 | bfin_wdt_keepalive(); |
270 | return 0; |
271 | case WDIOC_SETTIMEOUT: { |
272 | int new_timeout; |
273 | |
274 | if (get_user(new_timeout, p)) |
275 | return -EFAULT; |
276 | if (bfin_wdt_set_timeout(new_timeout)) |
277 | return -EINVAL; |
278 | } |
279 | /* Fall */ |
280 | case WDIOC_GETTIMEOUT: |
281 | return put_user(timeout, p); |
282 | default: |
283 | return -ENOTTY; |
284 | } |
285 | } |
286 | |
287 | #ifdef CONFIG_PM |
288 | static int state_before_suspend; |
289 | |
290 | /** |
291 | * bfin_wdt_suspend - suspend the watchdog |
292 | * @pdev: device being suspended |
293 | * @state: requested suspend state |
294 | * |
295 | * Remember if the watchdog was running and stop it. |
296 | * TODO: is this even right? Doesn't seem to be any |
297 | * standard in the watchdog world ... |
298 | */ |
299 | static int bfin_wdt_suspend(struct platform_device *pdev, pm_message_t state) |
300 | { |
301 | stampit(); |
302 | |
303 | state_before_suspend = bfin_wdt_running(); |
304 | bfin_wdt_stop(); |
305 | |
306 | return 0; |
307 | } |
308 | |
309 | /** |
310 | * bfin_wdt_resume - resume the watchdog |
311 | * @pdev: device being resumed |
312 | * |
313 | * If the watchdog was running, turn it back on. |
314 | */ |
315 | static int bfin_wdt_resume(struct platform_device *pdev) |
316 | { |
317 | stampit(); |
318 | |
319 | if (state_before_suspend) { |
320 | bfin_wdt_set_timeout(timeout); |
321 | bfin_wdt_start(); |
322 | } |
323 | |
324 | return 0; |
325 | } |
326 | #else |
327 | # define bfin_wdt_suspend NULL |
328 | # define bfin_wdt_resume NULL |
329 | #endif |
330 | |
331 | static const struct file_operations bfin_wdt_fops = { |
332 | .owner = THIS_MODULE, |
333 | .llseek = no_llseek, |
334 | .write = bfin_wdt_write, |
335 | .unlocked_ioctl = bfin_wdt_ioctl, |
336 | .open = bfin_wdt_open, |
337 | .release = bfin_wdt_release, |
338 | }; |
339 | |
340 | static struct miscdevice bfin_wdt_miscdev = { |
341 | .minor = WATCHDOG_MINOR, |
342 | .name = "watchdog", |
343 | .fops = &bfin_wdt_fops, |
344 | }; |
345 | |
346 | static const struct watchdog_info bfin_wdt_info = { |
347 | .identity = "Blackfin Watchdog", |
348 | .options = WDIOF_SETTIMEOUT | |
349 | WDIOF_KEEPALIVEPING | |
350 | WDIOF_MAGICCLOSE, |
351 | }; |
352 | |
353 | /** |
354 | * bfin_wdt_probe - Initialize module |
355 | * |
356 | * Registers the misc device. Actual device |
357 | * initialization is handled by bfin_wdt_open(). |
358 | */ |
359 | static int bfin_wdt_probe(struct platform_device *pdev) |
360 | { |
361 | int ret; |
362 | |
363 | ret = misc_register(&bfin_wdt_miscdev); |
364 | if (ret) { |
365 | pr_err("cannot register miscdev on minor=%d (err=%d)\n", |
366 | WATCHDOG_MINOR, ret); |
367 | return ret; |
368 | } |
369 | |
370 | pr_info("initialized: timeout=%d sec (nowayout=%d)\n", |
371 | timeout, nowayout); |
372 | |
373 | return 0; |
374 | } |
375 | |
376 | /** |
377 | * bfin_wdt_remove - Initialize module |
378 | * |
379 | * Unregisters the misc device. Actual device |
380 | * deinitialization is handled by bfin_wdt_close(). |
381 | */ |
382 | static int bfin_wdt_remove(struct platform_device *pdev) |
383 | { |
384 | misc_deregister(&bfin_wdt_miscdev); |
385 | return 0; |
386 | } |
387 | |
388 | /** |
389 | * bfin_wdt_shutdown - Soft Shutdown Handler |
390 | * |
391 | * Handles the soft shutdown event. |
392 | */ |
393 | static void bfin_wdt_shutdown(struct platform_device *pdev) |
394 | { |
395 | stampit(); |
396 | |
397 | bfin_wdt_stop(); |
398 | } |
399 | |
400 | static struct platform_device *bfin_wdt_device; |
401 | |
402 | static struct platform_driver bfin_wdt_driver = { |
403 | .probe = bfin_wdt_probe, |
404 | .remove = bfin_wdt_remove, |
405 | .shutdown = bfin_wdt_shutdown, |
406 | .suspend = bfin_wdt_suspend, |
407 | .resume = bfin_wdt_resume, |
408 | .driver = { |
409 | .name = WATCHDOG_NAME, |
410 | .owner = THIS_MODULE, |
411 | }, |
412 | }; |
413 | |
414 | /** |
415 | * bfin_wdt_init - Initialize module |
416 | * |
417 | * Checks the module params and registers the platform device & driver. |
418 | * Real work is in the platform probe function. |
419 | */ |
420 | static int __init bfin_wdt_init(void) |
421 | { |
422 | int ret; |
423 | |
424 | stampit(); |
425 | |
426 | /* Check that the timeout value is within range */ |
427 | if (bfin_wdt_set_timeout(timeout)) |
428 | return -EINVAL; |
429 | |
430 | /* Since this is an on-chip device and needs no board-specific |
431 | * resources, we'll handle all the platform device stuff here. |
432 | */ |
433 | ret = platform_driver_register(&bfin_wdt_driver); |
434 | if (ret) { |
435 | pr_err("unable to register driver\n"); |
436 | return ret; |
437 | } |
438 | |
439 | bfin_wdt_device = platform_device_register_simple(WATCHDOG_NAME, |
440 | -1, NULL, 0); |
441 | if (IS_ERR(bfin_wdt_device)) { |
442 | pr_err("unable to register device\n"); |
443 | platform_driver_unregister(&bfin_wdt_driver); |
444 | return PTR_ERR(bfin_wdt_device); |
445 | } |
446 | |
447 | return 0; |
448 | } |
449 | |
450 | /** |
451 | * bfin_wdt_exit - Deinitialize module |
452 | * |
453 | * Back out the platform device & driver steps. Real work is in the |
454 | * platform remove function. |
455 | */ |
456 | static void __exit bfin_wdt_exit(void) |
457 | { |
458 | platform_device_unregister(bfin_wdt_device); |
459 | platform_driver_unregister(&bfin_wdt_driver); |
460 | } |
461 | |
462 | module_init(bfin_wdt_init); |
463 | module_exit(bfin_wdt_exit); |
464 | |
465 | MODULE_AUTHOR("Michele d'Amico, Mike Frysinger <vapier@gentoo.org>"); |
466 | MODULE_DESCRIPTION("Blackfin Watchdog Device Driver"); |
467 | MODULE_LICENSE("GPL"); |
468 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |
469 | |
470 | module_param(timeout, uint, 0); |
471 | MODULE_PARM_DESC(timeout, |
472 | "Watchdog timeout in seconds. (1<=timeout<=((2^32)/SCLK), default=" |
473 | __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); |
474 | |
475 | module_param(nowayout, bool, 0); |
476 | MODULE_PARM_DESC(nowayout, |
477 | "Watchdog cannot be stopped once started (default=" |
478 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
479 |
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