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/drivers/watchdog/sbc60xxwdt.c

https://bitbucket.org/cyanogenmod/android_kernel_asus_tf300t
C | 398 lines | 245 code | 50 blank | 103 comment | 42 complexity | 352075dd2bf82e5404d5a88008fa1f70 MD5 | raw file
Possible License(s): LGPL-2.0, AGPL-1.0, GPL-2.0
  1/*
  2 *	60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x
  3 *
  4 *	Based on acquirewdt.c by Alan Cox.
  5 *
  6 *	This program is free software; you can redistribute it and/or
  7 *	modify it under the terms of the GNU General Public License
  8 *	as published by the Free Software Foundation; either version
  9 *	2 of the License, or (at your option) any later version.
 10 *
 11 *	The author does NOT admit liability nor provide warranty for
 12 *	any of this software. This material is provided "AS-IS" in
 13 *	the hope that it may be useful for others.
 14 *
 15 *	(c) Copyright 2000    Jakob Oestergaard <jakob@unthought.net>
 16 *
 17 *           12/4 - 2000      [Initial revision]
 18 *           25/4 - 2000      Added /dev/watchdog support
 19 *           09/5 - 2001      [smj@oro.net] fixed fop_write to "return 1"
 20 *					on success
 21 *           12/4 - 2002      [rob@osinvestor.com] eliminate fop_read
 22 *                            fix possible wdt_is_open race
 23 *                            add CONFIG_WATCHDOG_NOWAYOUT support
 24 *                            remove lock_kernel/unlock_kernel pairs
 25 *                            added KERN_* to printk's
 26 *                            got rid of extraneous comments
 27 *                            changed watchdog_info to correctly reflect what
 28 *			      the driver offers
 29 *			      added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,
 30 *			      WDIOC_SETTIMEOUT, WDIOC_GETTIMEOUT, and
 31 *			      WDIOC_SETOPTIONS ioctls
 32 *           09/8 - 2003      [wim@iguana.be] cleanup of trailing spaces
 33 *                            use module_param
 34 *                            made timeout (the emulated heartbeat) a
 35 *			      module_param
 36 *                            made the keepalive ping an internal subroutine
 37 *                            made wdt_stop and wdt_start module params
 38 *                            added extra printk's for startup problems
 39 *                            added MODULE_AUTHOR and MODULE_DESCRIPTION info
 40 *
 41 *
 42 *  This WDT driver is different from the other Linux WDT
 43 *  drivers in the following ways:
 44 *  *)  The driver will ping the watchdog by itself, because this
 45 *      particular WDT has a very short timeout (one second) and it
 46 *      would be insane to count on any userspace daemon always
 47 *      getting scheduled within that time frame.
 48 *
 49 */
 50
 51#include <linux/module.h>
 52#include <linux/moduleparam.h>
 53#include <linux/types.h>
 54#include <linux/timer.h>
 55#include <linux/jiffies.h>
 56#include <linux/miscdevice.h>
 57#include <linux/watchdog.h>
 58#include <linux/fs.h>
 59#include <linux/ioport.h>
 60#include <linux/notifier.h>
 61#include <linux/reboot.h>
 62#include <linux/init.h>
 63#include <linux/io.h>
 64#include <linux/uaccess.h>
 65
 66#include <asm/system.h>
 67
 68#define OUR_NAME "sbc60xxwdt"
 69#define PFX OUR_NAME ": "
 70
 71/*
 72 * You must set these - The driver cannot probe for the settings
 73 */
 74
 75static int wdt_stop = 0x45;
 76module_param(wdt_stop, int, 0);
 77MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
 78
 79static int wdt_start = 0x443;
 80module_param(wdt_start, int, 0);
 81MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)");
 82
 83/*
 84 * The 60xx board can use watchdog timeout values from one second
 85 * to several minutes.  The default is one second, so if we reset
 86 * the watchdog every ~250ms we should be safe.
 87 */
 88
 89#define WDT_INTERVAL (HZ/4+1)
 90
 91/*
 92 * We must not require too good response from the userspace daemon.
 93 * Here we require the userspace daemon to send us a heartbeat
 94 * char to /dev/watchdog every 30 seconds.
 95 * If the daemon pulses us every 25 seconds, we can still afford
 96 * a 5 second scheduling delay on the (high priority) daemon. That
 97 * should be sufficient for a box under any load.
 98 */
 99
100#define WATCHDOG_TIMEOUT 30		/* 30 sec default timeout */
101static int timeout = WATCHDOG_TIMEOUT;	/* in seconds, multiplied by HZ to
102					   get seconds to wait for a ping */
103module_param(timeout, int, 0);
104MODULE_PARM_DESC(timeout,
105	"Watchdog timeout in seconds. (1<=timeout<=3600, default="
106				__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
107
108static int nowayout = WATCHDOG_NOWAYOUT;
109module_param(nowayout, int, 0);
110MODULE_PARM_DESC(nowayout,
111	"Watchdog cannot be stopped once started (default="
112				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
113
114static void wdt_timer_ping(unsigned long);
115static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
116static unsigned long next_heartbeat;
117static unsigned long wdt_is_open;
118static char wdt_expect_close;
119
120/*
121 *	Whack the dog
122 */
123
124static void wdt_timer_ping(unsigned long data)
125{
126	/* If we got a heartbeat pulse within the WDT_US_INTERVAL
127	 * we agree to ping the WDT
128	 */
129	if (time_before(jiffies, next_heartbeat)) {
130		/* Ping the WDT by reading from wdt_start */
131		inb_p(wdt_start);
132		/* Re-set the timer interval */
133		mod_timer(&timer, jiffies + WDT_INTERVAL);
134	} else
135		printk(KERN_WARNING PFX
136			"Heartbeat lost! Will not ping the watchdog\n");
137}
138
139/*
140 * Utility routines
141 */
142
143static void wdt_startup(void)
144{
145	next_heartbeat = jiffies + (timeout * HZ);
146
147	/* Start the timer */
148	mod_timer(&timer, jiffies + WDT_INTERVAL);
149	printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
150}
151
152static void wdt_turnoff(void)
153{
154	/* Stop the timer */
155	del_timer(&timer);
156	inb_p(wdt_stop);
157	printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
158}
159
160static void wdt_keepalive(void)
161{
162	/* user land ping */
163	next_heartbeat = jiffies + (timeout * HZ);
164}
165
166/*
167 * /dev/watchdog handling
168 */
169
170static ssize_t fop_write(struct file *file, const char __user *buf,
171						size_t count, loff_t *ppos)
172{
173	/* See if we got the magic character 'V' and reload the timer */
174	if (count) {
175		if (!nowayout) {
176			size_t ofs;
177
178			/* note: just in case someone wrote the
179			   magic character five months ago... */
180			wdt_expect_close = 0;
181
182			/* scan to see whether or not we got the
183			   magic character */
184			for (ofs = 0; ofs != count; ofs++) {
185				char c;
186				if (get_user(c, buf + ofs))
187					return -EFAULT;
188				if (c == 'V')
189					wdt_expect_close = 42;
190			}
191		}
192
193		/* Well, anyhow someone wrote to us, we should
194		   return that favour */
195		wdt_keepalive();
196	}
197	return count;
198}
199
200static int fop_open(struct inode *inode, struct file *file)
201{
202	/* Just in case we're already talking to someone... */
203	if (test_and_set_bit(0, &wdt_is_open))
204		return -EBUSY;
205
206	if (nowayout)
207		__module_get(THIS_MODULE);
208
209	/* Good, fire up the show */
210	wdt_startup();
211	return nonseekable_open(inode, file);
212}
213
214static int fop_close(struct inode *inode, struct file *file)
215{
216	if (wdt_expect_close == 42)
217		wdt_turnoff();
218	else {
219		del_timer(&timer);
220		printk(KERN_CRIT PFX
221		  "device file closed unexpectedly. Will not stop the WDT!\n");
222	}
223	clear_bit(0, &wdt_is_open);
224	wdt_expect_close = 0;
225	return 0;
226}
227
228static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
229{
230	void __user *argp = (void __user *)arg;
231	int __user *p = argp;
232	static const struct watchdog_info ident = {
233		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
234							WDIOF_MAGICCLOSE,
235		.firmware_version = 1,
236		.identity = "SBC60xx",
237	};
238
239	switch (cmd) {
240	case WDIOC_GETSUPPORT:
241		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
242	case WDIOC_GETSTATUS:
243	case WDIOC_GETBOOTSTATUS:
244		return put_user(0, p);
245	case WDIOC_SETOPTIONS:
246	{
247		int new_options, retval = -EINVAL;
248		if (get_user(new_options, p))
249			return -EFAULT;
250		if (new_options & WDIOS_DISABLECARD) {
251			wdt_turnoff();
252			retval = 0;
253		}
254		if (new_options & WDIOS_ENABLECARD) {
255			wdt_startup();
256			retval = 0;
257		}
258		return retval;
259	}
260	case WDIOC_KEEPALIVE:
261		wdt_keepalive();
262		return 0;
263	case WDIOC_SETTIMEOUT:
264	{
265		int new_timeout;
266		if (get_user(new_timeout, p))
267			return -EFAULT;
268		/* arbitrary upper limit */
269		if (new_timeout < 1 || new_timeout > 3600)
270			return -EINVAL;
271
272		timeout = new_timeout;
273		wdt_keepalive();
274		/* Fall through */
275	}
276	case WDIOC_GETTIMEOUT:
277		return put_user(timeout, p);
278	default:
279		return -ENOTTY;
280	}
281}
282
283static const struct file_operations wdt_fops = {
284	.owner		= THIS_MODULE,
285	.llseek		= no_llseek,
286	.write		= fop_write,
287	.open		= fop_open,
288	.release	= fop_close,
289	.unlocked_ioctl	= fop_ioctl,
290};
291
292static struct miscdevice wdt_miscdev = {
293	.minor = WATCHDOG_MINOR,
294	.name = "watchdog",
295	.fops = &wdt_fops,
296};
297
298/*
299 *	Notifier for system down
300 */
301
302static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
303	void *unused)
304{
305	if (code == SYS_DOWN || code == SYS_HALT)
306		wdt_turnoff();
307	return NOTIFY_DONE;
308}
309
310/*
311 *	The WDT needs to learn about soft shutdowns in order to
312 *	turn the timebomb registers off.
313 */
314
315static struct notifier_block wdt_notifier = {
316	.notifier_call = wdt_notify_sys,
317};
318
319static void __exit sbc60xxwdt_unload(void)
320{
321	wdt_turnoff();
322
323	/* Deregister */
324	misc_deregister(&wdt_miscdev);
325
326	unregister_reboot_notifier(&wdt_notifier);
327	if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
328		release_region(wdt_stop, 1);
329	release_region(wdt_start, 1);
330}
331
332static int __init sbc60xxwdt_init(void)
333{
334	int rc = -EBUSY;
335
336	if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
337		timeout = WATCHDOG_TIMEOUT;
338		printk(KERN_INFO PFX
339			"timeout value must be 1 <= x <= 3600, using %d\n",
340								timeout);
341	}
342
343	if (!request_region(wdt_start, 1, "SBC 60XX WDT")) {
344		printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
345			wdt_start);
346		rc = -EIO;
347		goto err_out;
348	}
349
350	/* We cannot reserve 0x45 - the kernel already has! */
351	if (wdt_stop != 0x45 && wdt_stop != wdt_start) {
352		if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) {
353			printk(KERN_ERR PFX
354				"I/O address 0x%04x already in use\n",
355							wdt_stop);
356			rc = -EIO;
357			goto err_out_region1;
358		}
359	}
360
361	rc = register_reboot_notifier(&wdt_notifier);
362	if (rc) {
363		printk(KERN_ERR PFX
364			"cannot register reboot notifier (err=%d)\n", rc);
365		goto err_out_region2;
366	}
367
368	rc = misc_register(&wdt_miscdev);
369	if (rc) {
370		printk(KERN_ERR PFX
371			"cannot register miscdev on minor=%d (err=%d)\n",
372						wdt_miscdev.minor, rc);
373		goto err_out_reboot;
374	}
375	printk(KERN_INFO PFX
376		"WDT driver for 60XX single board computer initialised. "
377		"timeout=%d sec (nowayout=%d)\n", timeout, nowayout);
378
379	return 0;
380
381err_out_reboot:
382	unregister_reboot_notifier(&wdt_notifier);
383err_out_region2:
384	if (wdt_stop != 0x45 && wdt_stop != wdt_start)
385		release_region(wdt_stop, 1);
386err_out_region1:
387	release_region(wdt_start, 1);
388err_out:
389	return rc;
390}
391
392module_init(sbc60xxwdt_init);
393module_exit(sbc60xxwdt_unload);
394
395MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
396MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
397MODULE_LICENSE("GPL");
398MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);