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