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 */
bfin_wdt_keepalive(void)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 */
bfin_wdt_stop(void)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 */
bfin_wdt_start(void)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 */
bfin_wdt_running(void)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 */
bfin_wdt_set_timeout(unsigned long t)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 */
bfin_wdt_open(struct inode * inode,struct file * file)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 */
bfin_wdt_release(struct inode * inode,struct file * file)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 */
bfin_wdt_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)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 */
bfin_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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 */
bfin_wdt_suspend(struct platform_device * pdev,pm_message_t state)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 */
bfin_wdt_resume(struct platform_device * pdev)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 */
bfin_wdt_probe(struct platform_device * pdev)359 static int __devinit 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 */
bfin_wdt_remove(struct platform_device * pdev)382 static int __devexit 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 */
bfin_wdt_shutdown(struct platform_device * pdev)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 = __devexit_p(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 */
bfin_wdt_init(void)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 */
bfin_wdt_exit(void)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