Merge branch 'mini2440-dev-unlikely' into mini2440-dev
[linux-2.6/mini2440.git] / drivers / watchdog / bfin_wdt.c
blobc7b3f9df2317387401961450f9746ed093a97e27
1 /*
2 * Blackfin On-Chip Watchdog Driver
3 * Supports BF53[123]/BF53[467]/BF54[2489]/BF561
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@lxorguk.ukuu.org.uk>
10 * Enter bugs at http://blackfin.uclinux.org/
12 * Licensed under the GPL-2 or later.
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 <linux/uaccess.h>
28 #include <asm/blackfin.h>
30 #define stamp(fmt, args...) \
31 pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args)
32 #define stampit() stamp("here i am")
33 #define pr_devinit(fmt, args...) \
34 ({ static const __devinitconst char __fmt[] = fmt; \
35 printk(__fmt, ## args); })
36 #define pr_init(fmt, args...) \
37 ({ static const __initconst char __fmt[] = fmt; \
38 printk(__fmt, ## args); })
40 #define WATCHDOG_NAME "bfin-wdt"
41 #define PFX WATCHDOG_NAME ": "
43 /* The BF561 has two watchdogs (one per core), but since Linux
44 * only runs on core A, we'll just work with that one.
46 #ifdef BF561_FAMILY
47 # define bfin_read_WDOG_CTL() bfin_read_WDOGA_CTL()
48 # define bfin_read_WDOG_CNT() bfin_read_WDOGA_CNT()
49 # define bfin_read_WDOG_STAT() bfin_read_WDOGA_STAT()
50 # define bfin_write_WDOG_CTL(x) bfin_write_WDOGA_CTL(x)
51 # define bfin_write_WDOG_CNT(x) bfin_write_WDOGA_CNT(x)
52 # define bfin_write_WDOG_STAT(x) bfin_write_WDOGA_STAT(x)
53 #endif
55 /* Bit in SWRST that indicates boot caused by watchdog */
56 #define SWRST_RESET_WDOG 0x4000
58 /* Bit in WDOG_CTL that indicates watchdog has expired (WDR0) */
59 #define WDOG_EXPIRED 0x8000
61 /* Masks for WDEV field in WDOG_CTL register */
62 #define ICTL_RESET 0x0
63 #define ICTL_NMI 0x2
64 #define ICTL_GPI 0x4
65 #define ICTL_NONE 0x6
66 #define ICTL_MASK 0x6
68 /* Masks for WDEN field in WDOG_CTL register */
69 #define WDEN_MASK 0x0FF0
70 #define WDEN_ENABLE 0x0000
71 #define WDEN_DISABLE 0x0AD0
73 /* some defaults */
74 #define WATCHDOG_TIMEOUT 20
76 static unsigned int timeout = WATCHDOG_TIMEOUT;
77 static int nowayout = WATCHDOG_NOWAYOUT;
78 static struct watchdog_info bfin_wdt_info;
79 static unsigned long open_check;
80 static char expect_close;
81 static DEFINE_SPINLOCK(bfin_wdt_spinlock);
83 /**
84 * bfin_wdt_keepalive - Keep the Userspace Watchdog Alive
86 * The Userspace watchdog got a KeepAlive: schedule the next timeout.
88 static int bfin_wdt_keepalive(void)
90 stampit();
91 bfin_write_WDOG_STAT(0);
92 return 0;
95 /**
96 * bfin_wdt_stop - Stop the Watchdog
98 * Stops the on-chip watchdog.
100 static int bfin_wdt_stop(void)
102 stampit();
103 bfin_write_WDOG_CTL(WDEN_DISABLE);
104 return 0;
108 * bfin_wdt_start - Start the Watchdog
110 * Starts the on-chip watchdog. Automatically loads WDOG_CNT
111 * into WDOG_STAT for us.
113 static int bfin_wdt_start(void)
115 stampit();
116 bfin_write_WDOG_CTL(WDEN_ENABLE | ICTL_RESET);
117 return 0;
121 * bfin_wdt_running - Check Watchdog status
123 * See if the watchdog is running.
125 static int bfin_wdt_running(void)
127 stampit();
128 return ((bfin_read_WDOG_CTL() & WDEN_MASK) != WDEN_DISABLE);
132 * bfin_wdt_set_timeout - Set the Userspace Watchdog timeout
133 * @t: new timeout value (in seconds)
135 * Translate the specified timeout in seconds into System Clock
136 * terms which is what the on-chip Watchdog requires.
138 static int bfin_wdt_set_timeout(unsigned long t)
140 u32 cnt;
141 unsigned long flags;
143 stampit();
145 cnt = t * get_sclk();
146 if (cnt < get_sclk()) {
147 printk(KERN_WARNING PFX "timeout value is too large\n");
148 return -EINVAL;
151 spin_lock_irqsave(&bfin_wdt_spinlock, flags);
153 int run = bfin_wdt_running();
154 bfin_wdt_stop();
155 bfin_write_WDOG_CNT(cnt);
156 if (run)
157 bfin_wdt_start();
159 spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
161 timeout = t;
163 return 0;
167 * bfin_wdt_open - Open the Device
168 * @inode: inode of device
169 * @file: file handle of device
171 * Watchdog device is opened and started.
173 static int bfin_wdt_open(struct inode *inode, struct file *file)
175 stampit();
177 if (test_and_set_bit(0, &open_check))
178 return -EBUSY;
180 if (nowayout)
181 __module_get(THIS_MODULE);
183 bfin_wdt_keepalive();
184 bfin_wdt_start();
186 return nonseekable_open(inode, file);
190 * bfin_wdt_close - Close the Device
191 * @inode: inode of device
192 * @file: file handle of device
194 * Watchdog device is closed and stopped.
196 static int bfin_wdt_release(struct inode *inode, struct file *file)
198 stampit();
200 if (expect_close == 42)
201 bfin_wdt_stop();
202 else {
203 printk(KERN_CRIT PFX
204 "Unexpected close, not stopping watchdog!\n");
205 bfin_wdt_keepalive();
207 expect_close = 0;
208 clear_bit(0, &open_check);
209 return 0;
213 * bfin_wdt_write - Write to Device
214 * @file: file handle of device
215 * @buf: buffer to write
216 * @count: length of buffer
217 * @ppos: offset
219 * Pings the watchdog on write.
221 static ssize_t bfin_wdt_write(struct file *file, const char __user *data,
222 size_t len, loff_t *ppos)
224 stampit();
226 if (len) {
227 if (!nowayout) {
228 size_t i;
230 /* In case it was set long ago */
231 expect_close = 0;
233 for (i = 0; i != len; i++) {
234 char c;
235 if (get_user(c, data + i))
236 return -EFAULT;
237 if (c == 'V')
238 expect_close = 42;
241 bfin_wdt_keepalive();
244 return len;
248 * bfin_wdt_ioctl - Query Device
249 * @file: file handle of device
250 * @cmd: watchdog command
251 * @arg: argument
253 * Query basic information from the device or ping it, as outlined by the
254 * watchdog API.
256 static long bfin_wdt_ioctl(struct file *file,
257 unsigned int cmd, unsigned long arg)
259 void __user *argp = (void __user *)arg;
260 int __user *p = argp;
262 stampit();
264 switch (cmd) {
265 case WDIOC_GETSUPPORT:
266 if (copy_to_user(argp, &bfin_wdt_info, sizeof(bfin_wdt_info)))
267 return -EFAULT;
268 else
269 return 0;
270 case WDIOC_GETSTATUS:
271 case WDIOC_GETBOOTSTATUS:
272 return put_user(!!(_bfin_swrst & SWRST_RESET_WDOG), p);
273 case WDIOC_SETOPTIONS: {
274 unsigned long flags;
275 int options, ret = -EINVAL;
277 if (get_user(options, p))
278 return -EFAULT;
280 spin_lock_irqsave(&bfin_wdt_spinlock, flags);
281 if (options & WDIOS_DISABLECARD) {
282 bfin_wdt_stop();
283 ret = 0;
285 if (options & WDIOS_ENABLECARD) {
286 bfin_wdt_start();
287 ret = 0;
289 spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
290 return ret;
292 case WDIOC_KEEPALIVE:
293 bfin_wdt_keepalive();
294 return 0;
295 case WDIOC_SETTIMEOUT: {
296 int new_timeout;
298 if (get_user(new_timeout, p))
299 return -EFAULT;
300 if (bfin_wdt_set_timeout(new_timeout))
301 return -EINVAL;
303 /* Fall */
304 case WDIOC_GETTIMEOUT:
305 return put_user(timeout, p);
306 default:
307 return -ENOTTY;
312 * bfin_wdt_notify_sys - Notifier Handler
313 * @this: notifier block
314 * @code: notifier event
315 * @unused: unused
317 * Handles specific events, such as turning off the watchdog during a
318 * shutdown event.
320 static int bfin_wdt_notify_sys(struct notifier_block *this,
321 unsigned long code, void *unused)
323 stampit();
325 if (code == SYS_DOWN || code == SYS_HALT)
326 bfin_wdt_stop();
328 return NOTIFY_DONE;
331 #ifdef CONFIG_PM
332 static int state_before_suspend;
335 * bfin_wdt_suspend - suspend the watchdog
336 * @pdev: device being suspended
337 * @state: requested suspend state
339 * Remember if the watchdog was running and stop it.
340 * TODO: is this even right? Doesn't seem to be any
341 * standard in the watchdog world ...
343 static int bfin_wdt_suspend(struct platform_device *pdev, pm_message_t state)
345 stampit();
347 state_before_suspend = bfin_wdt_running();
348 bfin_wdt_stop();
350 return 0;
354 * bfin_wdt_resume - resume the watchdog
355 * @pdev: device being resumed
357 * If the watchdog was running, turn it back on.
359 static int bfin_wdt_resume(struct platform_device *pdev)
361 stampit();
363 if (state_before_suspend) {
364 bfin_wdt_set_timeout(timeout);
365 bfin_wdt_start();
368 return 0;
370 #else
371 # define bfin_wdt_suspend NULL
372 # define bfin_wdt_resume NULL
373 #endif
375 static const struct file_operations bfin_wdt_fops = {
376 .owner = THIS_MODULE,
377 .llseek = no_llseek,
378 .write = bfin_wdt_write,
379 .unlocked_ioctl = bfin_wdt_ioctl,
380 .open = bfin_wdt_open,
381 .release = bfin_wdt_release,
384 static struct miscdevice bfin_wdt_miscdev = {
385 .minor = WATCHDOG_MINOR,
386 .name = "watchdog",
387 .fops = &bfin_wdt_fops,
390 static struct watchdog_info bfin_wdt_info = {
391 .identity = "Blackfin Watchdog",
392 .options = WDIOF_SETTIMEOUT |
393 WDIOF_KEEPALIVEPING |
394 WDIOF_MAGICCLOSE,
397 static struct notifier_block bfin_wdt_notifier = {
398 .notifier_call = bfin_wdt_notify_sys,
402 * bfin_wdt_probe - Initialize module
404 * Registers the misc device and notifier handler. Actual device
405 * initialization is handled by bfin_wdt_open().
407 static int __devinit bfin_wdt_probe(struct platform_device *pdev)
409 int ret;
411 ret = register_reboot_notifier(&bfin_wdt_notifier);
412 if (ret) {
413 pr_devinit(KERN_ERR PFX
414 "cannot register reboot notifier (err=%d)\n", ret);
415 return ret;
418 ret = misc_register(&bfin_wdt_miscdev);
419 if (ret) {
420 pr_devinit(KERN_ERR PFX
421 "cannot register miscdev on minor=%d (err=%d)\n",
422 WATCHDOG_MINOR, ret);
423 unregister_reboot_notifier(&bfin_wdt_notifier);
424 return ret;
427 pr_devinit(KERN_INFO PFX "initialized: timeout=%d sec (nowayout=%d)\n",
428 timeout, nowayout);
430 return 0;
434 * bfin_wdt_remove - Initialize module
436 * Unregisters the misc device and notifier handler. Actual device
437 * deinitialization is handled by bfin_wdt_close().
439 static int __devexit bfin_wdt_remove(struct platform_device *pdev)
441 misc_deregister(&bfin_wdt_miscdev);
442 unregister_reboot_notifier(&bfin_wdt_notifier);
443 return 0;
446 static struct platform_device *bfin_wdt_device;
448 static struct platform_driver bfin_wdt_driver = {
449 .probe = bfin_wdt_probe,
450 .remove = __devexit_p(bfin_wdt_remove),
451 .suspend = bfin_wdt_suspend,
452 .resume = bfin_wdt_resume,
453 .driver = {
454 .name = WATCHDOG_NAME,
455 .owner = THIS_MODULE,
460 * bfin_wdt_init - Initialize module
462 * Checks the module params and registers the platform device & driver.
463 * Real work is in the platform probe function.
465 static int __init bfin_wdt_init(void)
467 int ret;
469 stampit();
471 /* Check that the timeout value is within range */
472 if (bfin_wdt_set_timeout(timeout))
473 return -EINVAL;
475 /* Since this is an on-chip device and needs no board-specific
476 * resources, we'll handle all the platform device stuff here.
478 ret = platform_driver_register(&bfin_wdt_driver);
479 if (ret) {
480 pr_init(KERN_ERR PFX "unable to register driver\n");
481 return ret;
484 bfin_wdt_device = platform_device_register_simple(WATCHDOG_NAME,
485 -1, NULL, 0);
486 if (IS_ERR(bfin_wdt_device)) {
487 pr_init(KERN_ERR PFX "unable to register device\n");
488 platform_driver_unregister(&bfin_wdt_driver);
489 return PTR_ERR(bfin_wdt_device);
492 return 0;
496 * bfin_wdt_exit - Deinitialize module
498 * Back out the platform device & driver steps. Real work is in the
499 * platform remove function.
501 static void __exit bfin_wdt_exit(void)
503 platform_device_unregister(bfin_wdt_device);
504 platform_driver_unregister(&bfin_wdt_driver);
507 module_init(bfin_wdt_init);
508 module_exit(bfin_wdt_exit);
510 MODULE_AUTHOR("Michele d'Amico, Mike Frysinger <vapier@gentoo.org>");
511 MODULE_DESCRIPTION("Blackfin Watchdog Device Driver");
512 MODULE_LICENSE("GPL");
513 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
515 module_param(timeout, uint, 0);
516 MODULE_PARM_DESC(timeout,
517 "Watchdog timeout in seconds. (1<=timeout<=((2^32)/SCLK), default="
518 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
520 module_param(nowayout, int, 0);
521 MODULE_PARM_DESC(nowayout,
522 "Watchdog cannot be stopped once started (default="
523 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");