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Bryan Wu1e6d3202007-07-15 02:50:02 +08001/*
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")
Mike Frysinger93539b12008-03-27 11:53:32 -070032#define pr_devinit(fmt, args...) ({ static const __devinitconst char __fmt[] = fmt; printk(__fmt, ## args); })
33#define pr_init(fmt, args...) ({ static const __initconst char __fmt[] = fmt; printk(__fmt, ## args); })
Bryan Wu1e6d3202007-07-15 02:50:02 +080034
35#define WATCHDOG_NAME "bfin-wdt"
36#define PFX WATCHDOG_NAME ": "
37
38/* The BF561 has two watchdogs (one per core), but since Linux
39 * only runs on core A, we'll just work with that one.
40 */
41#ifdef BF561_FAMILY
42# define bfin_read_WDOG_CTL() bfin_read_WDOGA_CTL()
43# define bfin_read_WDOG_CNT() bfin_read_WDOGA_CNT()
44# define bfin_read_WDOG_STAT() bfin_read_WDOGA_STAT()
45# define bfin_write_WDOG_CTL(x) bfin_write_WDOGA_CTL(x)
46# define bfin_write_WDOG_CNT(x) bfin_write_WDOGA_CNT(x)
47# define bfin_write_WDOG_STAT(x) bfin_write_WDOGA_STAT(x)
48#endif
49
50/* Bit in SWRST that indicates boot caused by watchdog */
51#define SWRST_RESET_WDOG 0x4000
52
53/* Bit in WDOG_CTL that indicates watchdog has expired (WDR0) */
54#define WDOG_EXPIRED 0x8000
55
56/* Masks for WDEV field in WDOG_CTL register */
57#define ICTL_RESET 0x0
58#define ICTL_NMI 0x2
59#define ICTL_GPI 0x4
60#define ICTL_NONE 0x6
61#define ICTL_MASK 0x6
62
63/* Masks for WDEN field in WDOG_CTL register */
64#define WDEN_MASK 0x0FF0
65#define WDEN_ENABLE 0x0000
66#define WDEN_DISABLE 0x0AD0
67
68/* some defaults */
69#define WATCHDOG_TIMEOUT 20
70
71static unsigned int timeout = WATCHDOG_TIMEOUT;
72static int nowayout = WATCHDOG_NOWAYOUT;
73static struct watchdog_info bfin_wdt_info;
74static unsigned long open_check;
75static char expect_close;
Jiri Slabybf6350a2007-11-10 05:58:44 +010076static DEFINE_SPINLOCK(bfin_wdt_spinlock);
Bryan Wu1e6d3202007-07-15 02:50:02 +080077
78/**
79 * bfin_wdt_keepalive - Keep the Userspace Watchdog Alive
80 *
81 * The Userspace watchdog got a KeepAlive: schedule the next timeout.
82 */
83static int bfin_wdt_keepalive(void)
84{
85 stampit();
86 bfin_write_WDOG_STAT(0);
87 return 0;
88}
89
90/**
91 * bfin_wdt_stop - Stop the Watchdog
92 *
93 * Stops the on-chip watchdog.
94 */
95static int bfin_wdt_stop(void)
96{
97 stampit();
98 bfin_write_WDOG_CTL(WDEN_DISABLE);
99 return 0;
100}
101
102/**
103 * bfin_wdt_start - Start the Watchdog
104 *
105 * Starts the on-chip watchdog. Automatically loads WDOG_CNT
106 * into WDOG_STAT for us.
107 */
108static int bfin_wdt_start(void)
109{
110 stampit();
111 bfin_write_WDOG_CTL(WDEN_ENABLE | ICTL_RESET);
112 return 0;
113}
114
115/**
116 * bfin_wdt_running - Check Watchdog status
117 *
118 * See if the watchdog is running.
119 */
120static int bfin_wdt_running(void)
121{
122 stampit();
123 return ((bfin_read_WDOG_CTL() & WDEN_MASK) != WDEN_DISABLE);
124}
125
126/**
127 * bfin_wdt_set_timeout - Set the Userspace Watchdog timeout
128 * @t: new timeout value (in seconds)
129 *
130 * Translate the specified timeout in seconds into System Clock
131 * terms which is what the on-chip Watchdog requires.
132 */
133static int bfin_wdt_set_timeout(unsigned long t)
134{
135 u32 cnt;
136 unsigned long flags;
137
138 stampit();
139
140 cnt = t * get_sclk();
141 if (cnt < get_sclk()) {
142 printk(KERN_WARNING PFX "timeout value is too large\n");
143 return -EINVAL;
144 }
145
146 spin_lock_irqsave(&bfin_wdt_spinlock, flags);
147 {
148 int run = bfin_wdt_running();
149 bfin_wdt_stop();
150 bfin_write_WDOG_CNT(cnt);
151 if (run) bfin_wdt_start();
152 }
153 spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
154
155 timeout = t;
156
157 return 0;
158}
159
160/**
161 * bfin_wdt_open - Open the Device
162 * @inode: inode of device
163 * @file: file handle of device
164 *
165 * Watchdog device is opened and started.
166 */
167static int bfin_wdt_open(struct inode *inode, struct file *file)
168{
169 stampit();
170
171 if (test_and_set_bit(0, &open_check))
172 return -EBUSY;
173
174 if (nowayout)
175 __module_get(THIS_MODULE);
176
177 bfin_wdt_keepalive();
178 bfin_wdt_start();
179
180 return nonseekable_open(inode, file);
181}
182
183/**
184 * bfin_wdt_close - Close the Device
185 * @inode: inode of device
186 * @file: file handle of device
187 *
188 * Watchdog device is closed and stopped.
189 */
190static int bfin_wdt_release(struct inode *inode, struct file *file)
191{
192 stampit();
193
194 if (expect_close == 42) {
195 bfin_wdt_stop();
196 } else {
197 printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
198 bfin_wdt_keepalive();
199 }
200
201 expect_close = 0;
202 clear_bit(0, &open_check);
203
204 return 0;
205}
206
207/**
208 * bfin_wdt_write - Write to Device
209 * @file: file handle of device
210 * @buf: buffer to write
211 * @count: length of buffer
212 * @ppos: offset
213 *
214 * Pings the watchdog on write.
215 */
216static ssize_t bfin_wdt_write(struct file *file, const char __user *data,
217 size_t len, loff_t *ppos)
218{
219 stampit();
220
221 if (len) {
222 if (!nowayout) {
223 size_t i;
224
225 /* In case it was set long ago */
226 expect_close = 0;
227
228 for (i = 0; i != len; i++) {
229 char c;
230 if (get_user(c, data + i))
231 return -EFAULT;
232 if (c == 'V')
233 expect_close = 42;
234 }
235 }
236 bfin_wdt_keepalive();
237 }
238
239 return len;
240}
241
242/**
243 * bfin_wdt_ioctl - Query Device
244 * @inode: inode of device
245 * @file: file handle of device
246 * @cmd: watchdog command
247 * @arg: argument
248 *
249 * Query basic information from the device or ping it, as outlined by the
250 * watchdog API.
251 */
252static int bfin_wdt_ioctl(struct inode *inode, struct file *file,
253 unsigned int cmd, unsigned long arg)
254{
255 void __user *argp = (void __user *)arg;
256 int __user *p = argp;
257
258 stampit();
259
260 switch (cmd) {
261 default:
262 return -ENOTTY;
263
264 case WDIOC_GETSUPPORT:
265 if (copy_to_user(argp, &bfin_wdt_info, sizeof(bfin_wdt_info)))
266 return -EFAULT;
267 else
268 return 0;
269
270 case WDIOC_GETSTATUS:
271 case WDIOC_GETBOOTSTATUS:
272 return put_user(!!(_bfin_swrst & SWRST_RESET_WDOG), p);
273
274 case WDIOC_KEEPALIVE:
275 bfin_wdt_keepalive();
276 return 0;
277
278 case WDIOC_SETTIMEOUT: {
279 int new_timeout;
280
281 if (get_user(new_timeout, p))
282 return -EFAULT;
283
284 if (bfin_wdt_set_timeout(new_timeout))
285 return -EINVAL;
286 }
287 /* Fall */
288 case WDIOC_GETTIMEOUT:
289 return put_user(timeout, p);
290
291 case WDIOC_SETOPTIONS: {
292 unsigned long flags;
293 int options, ret = -EINVAL;
294
295 if (get_user(options, p))
296 return -EFAULT;
297
298 spin_lock_irqsave(&bfin_wdt_spinlock, flags);
299
300 if (options & WDIOS_DISABLECARD) {
301 bfin_wdt_stop();
302 ret = 0;
303 }
304
305 if (options & WDIOS_ENABLECARD) {
306 bfin_wdt_start();
307 ret = 0;
308 }
309
310 spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
311
312 return ret;
313 }
314 }
315}
316
317/**
318 * bfin_wdt_notify_sys - Notifier Handler
319 * @this: notifier block
320 * @code: notifier event
321 * @unused: unused
322 *
323 * Handles specific events, such as turning off the watchdog during a
324 * shutdown event.
325 */
326static int bfin_wdt_notify_sys(struct notifier_block *this, unsigned long code,
327 void *unused)
328{
329 stampit();
330
331 if (code == SYS_DOWN || code == SYS_HALT)
332 bfin_wdt_stop();
333
334 return NOTIFY_DONE;
335}
336
337#ifdef CONFIG_PM
338static int state_before_suspend;
339
340/**
341 * bfin_wdt_suspend - suspend the watchdog
342 * @pdev: device being suspended
343 * @state: requested suspend state
344 *
345 * Remember if the watchdog was running and stop it.
346 * TODO: is this even right? Doesn't seem to be any
347 * standard in the watchdog world ...
348 */
349static int bfin_wdt_suspend(struct platform_device *pdev, pm_message_t state)
350{
351 stampit();
352
353 state_before_suspend = bfin_wdt_running();
354 bfin_wdt_stop();
355
356 return 0;
357}
358
359/**
360 * bfin_wdt_resume - resume the watchdog
361 * @pdev: device being resumed
362 *
363 * If the watchdog was running, turn it back on.
364 */
365static int bfin_wdt_resume(struct platform_device *pdev)
366{
367 stampit();
368
369 if (state_before_suspend) {
370 bfin_wdt_set_timeout(timeout);
371 bfin_wdt_start();
372 }
373
374 return 0;
375}
376#else
377# define bfin_wdt_suspend NULL
378# define bfin_wdt_resume NULL
379#endif
380
Jan Engelhardtb47a1662008-01-22 20:48:10 +0100381static const struct file_operations bfin_wdt_fops = {
Bryan Wu1e6d3202007-07-15 02:50:02 +0800382 .owner = THIS_MODULE,
383 .llseek = no_llseek,
384 .write = bfin_wdt_write,
385 .ioctl = bfin_wdt_ioctl,
386 .open = bfin_wdt_open,
387 .release = bfin_wdt_release,
388};
389
390static struct miscdevice bfin_wdt_miscdev = {
391 .minor = WATCHDOG_MINOR,
392 .name = "watchdog",
393 .fops = &bfin_wdt_fops,
394};
395
396static struct watchdog_info bfin_wdt_info = {
397 .identity = "Blackfin Watchdog",
398 .options = WDIOF_SETTIMEOUT |
399 WDIOF_KEEPALIVEPING |
400 WDIOF_MAGICCLOSE,
401};
402
403static struct notifier_block bfin_wdt_notifier = {
404 .notifier_call = bfin_wdt_notify_sys,
405};
406
407/**
Mike Frysinger93539b12008-03-27 11:53:32 -0700408 * bfin_wdt_probe - Initialize module
409 *
410 * Registers the misc device and notifier handler. Actual device
411 * initialization is handled by bfin_wdt_open().
412 */
413static int __devinit bfin_wdt_probe(struct platform_device *pdev)
414{
415 int ret;
416
417 ret = register_reboot_notifier(&bfin_wdt_notifier);
418 if (ret) {
419 pr_devinit(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n", ret);
420 return ret;
421 }
422
423 ret = misc_register(&bfin_wdt_miscdev);
424 if (ret) {
425 pr_devinit(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
426 WATCHDOG_MINOR, ret);
427 unregister_reboot_notifier(&bfin_wdt_notifier);
428 return ret;
429 }
430
431 pr_devinit(KERN_INFO PFX "initialized: timeout=%d sec (nowayout=%d)\n",
432 timeout, nowayout);
433
434 return 0;
435}
436
437/**
438 * bfin_wdt_remove - Initialize module
439 *
440 * Unregisters the misc device and notifier handler. Actual device
441 * deinitialization is handled by bfin_wdt_close().
442 */
443static int __devexit bfin_wdt_remove(struct platform_device *pdev)
444{
445 misc_deregister(&bfin_wdt_miscdev);
446 unregister_reboot_notifier(&bfin_wdt_notifier);
447 return 0;
448}
449
450static struct platform_device *bfin_wdt_device;
451
452static struct platform_driver bfin_wdt_driver = {
453 .probe = bfin_wdt_probe,
454 .remove = __devexit_p(bfin_wdt_remove),
455 .suspend = bfin_wdt_suspend,
456 .resume = bfin_wdt_resume,
457 .driver = {
458 .name = WATCHDOG_NAME,
459 .owner = THIS_MODULE,
460 },
461};
462
463/**
Bryan Wu1e6d3202007-07-15 02:50:02 +0800464 * bfin_wdt_init - Initialize module
465 *
Mike Frysinger93539b12008-03-27 11:53:32 -0700466 * Checks the module params and registers the platform device & driver.
467 * Real work is in the platform probe function.
Bryan Wu1e6d3202007-07-15 02:50:02 +0800468 */
469static int __init bfin_wdt_init(void)
470{
471 int ret;
472
473 stampit();
474
475 /* Check that the timeout value is within range */
476 if (bfin_wdt_set_timeout(timeout))
477 return -EINVAL;
478
479 /* Since this is an on-chip device and needs no board-specific
480 * resources, we'll handle all the platform device stuff here.
481 */
Mike Frysinger93539b12008-03-27 11:53:32 -0700482 ret = platform_driver_register(&bfin_wdt_driver);
Bryan Wu1e6d3202007-07-15 02:50:02 +0800483 if (ret) {
Mike Frysinger93539b12008-03-27 11:53:32 -0700484 pr_init(KERN_ERR PFX "unable to register driver\n");
Bryan Wu1e6d3202007-07-15 02:50:02 +0800485 return ret;
486 }
487
Mike Frysinger93539b12008-03-27 11:53:32 -0700488 bfin_wdt_device = platform_device_register_simple(WATCHDOG_NAME, -1, NULL, 0);
489 if (IS_ERR(bfin_wdt_device)) {
490 pr_init(KERN_ERR PFX "unable to register device\n");
491 platform_driver_unregister(&bfin_wdt_driver);
492 return PTR_ERR(bfin_wdt_device);
Bryan Wu1e6d3202007-07-15 02:50:02 +0800493 }
494
Bryan Wu1e6d3202007-07-15 02:50:02 +0800495 return 0;
496}
497
498/**
499 * bfin_wdt_exit - Deinitialize module
500 *
Mike Frysinger93539b12008-03-27 11:53:32 -0700501 * Back out the platform device & driver steps. Real work is in the
502 * platform remove function.
Bryan Wu1e6d3202007-07-15 02:50:02 +0800503 */
504static void __exit bfin_wdt_exit(void)
505{
Mike Frysinger93539b12008-03-27 11:53:32 -0700506 platform_device_unregister(bfin_wdt_device);
507 platform_driver_unregister(&bfin_wdt_driver);
Bryan Wu1e6d3202007-07-15 02:50:02 +0800508}
509
510module_init(bfin_wdt_init);
511module_exit(bfin_wdt_exit);
512
513MODULE_AUTHOR("Michele d'Amico, Mike Frysinger <vapier@gentoo.org>");
514MODULE_DESCRIPTION("Blackfin Watchdog Device Driver");
515MODULE_LICENSE("GPL");
516MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
517
518module_param(timeout, uint, 0);
519MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=((2^32)/SCLK), default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
520
521module_param(nowayout, int, 0);
522MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");