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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * AMD Elan SC520 processor Watchdog Timer driver
3 *
Wim Van Sebroeck143a2e52009-03-18 08:35:09 +00004 * Based on acquirewdt.c by Alan Cox,
5 * and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
Linus Torvalds1da177e2005-04-16 15:20:36 -07006 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 *
12 * The authors do NOT admit liability nor provide warranty for
13 * any of this software. This material is provided "AS-IS" in
Wim Van Sebroeck143a2e52009-03-18 08:35:09 +000014 * the hope that it may be useful for others.
Linus Torvalds1da177e2005-04-16 15:20:36 -070015 *
16 * (c) Copyright 2001 Scott Jennings <linuxdrivers@oro.net>
17 * 9/27 - 2001 [Initial release]
18 *
19 * Additional fixes Alan Cox
20 * - Fixed formatting
21 * - Removed debug printks
22 * - Fixed SMP built kernel deadlock
23 * - Switched to private locks not lock_kernel
24 * - Used ioremap/writew/readw
25 * - Added NOWAYOUT support
26 * 4/12 - 2002 Changes by Rob Radez <rob@osinvestor.com>
27 * - Change comments
28 * - Eliminate fop_llseek
29 * - Change CONFIG_WATCHDOG_NOWAYOUT semantics
30 * - Add KERN_* tags to printks
31 * - fix possible wdt_is_open race
32 * - Report proper capabilities in watchdog_info
33 * - Add WDIOC_{GETSTATUS, GETBOOTSTATUS, SETTIMEOUT,
34 * GETTIMEOUT, SETOPTIONS} ioctls
35 * 09/8 - 2003 Changes by Wim Van Sebroeck <wim@iguana.be>
36 * - cleanup of trailing spaces
37 * - added extra printk's for startup problems
38 * - use module_param
39 * - made timeout (the emulated heartbeat) a module_param
40 * - made the keepalive ping an internal subroutine
41 * 3/27 - 2004 Changes by Sean Young <sean@mess.org>
42 * - set MMCR_BASE to 0xfffef000
43 * - CBAR does not need to be read
44 * - removed debugging printks
45 *
46 * This WDT driver is different from most other Linux WDT
47 * drivers in that the driver will ping the watchdog by itself,
48 * because this particular WDT has a very short timeout (1.6
49 * seconds) and it would be insane to count on any userspace
50 * daemon always getting scheduled within that time frame.
51 *
52 * This driver uses memory mapped IO, and spinlock.
53 */
54
55#include <linux/module.h>
56#include <linux/moduleparam.h>
57#include <linux/types.h>
58#include <linux/timer.h>
59#include <linux/miscdevice.h>
60#include <linux/watchdog.h>
61#include <linux/fs.h>
62#include <linux/ioport.h>
63#include <linux/notifier.h>
64#include <linux/reboot.h>
65#include <linux/init.h>
Tim Schmielau4e57b682005-10-30 15:03:48 -080066#include <linux/jiffies.h>
Alan Coxff948062008-05-19 14:08:44 +010067#include <linux/io.h>
68#include <linux/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070069
Linus Torvalds1da177e2005-04-16 15:20:36 -070070#include <asm/system.h>
71
72#define OUR_NAME "sc520_wdt"
73#define PFX OUR_NAME ": "
74
75/*
76 * The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7)
77 *
78 * 0: 492us 2: 1.01s 4: 4.03s 6: 16.22s
79 * 1: 503ms 3: 2.01s 5: 8.05s 7: 32.21s
80 *
81 * We will program the SC520 watchdog for a timeout of 2.01s.
82 * If we reset the watchdog every ~250ms we should be safe.
83 */
84
85#define WDT_INTERVAL (HZ/4+1)
86
87/*
88 * We must not require too good response from the userspace daemon.
89 * Here we require the userspace daemon to send us a heartbeat
90 * char to /dev/watchdog every 30 seconds.
91 */
92
93#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
Alan Coxff948062008-05-19 14:08:44 +010094/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
95static int timeout = WATCHDOG_TIMEOUT;
Linus Torvalds1da177e2005-04-16 15:20:36 -070096module_param(timeout, int, 0);
Alan Coxff948062008-05-19 14:08:44 +010097MODULE_PARM_DESC(timeout,
98 "Watchdog timeout in seconds. (1 <= timeout <= 3600, default="
99 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100
Andrey Panin4bfdf372005-07-27 11:43:58 -0700101static int nowayout = WATCHDOG_NOWAYOUT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102module_param(nowayout, int, 0);
Alan Coxff948062008-05-19 14:08:44 +0100103MODULE_PARM_DESC(nowayout,
104 "Watchdog cannot be stopped once started (default="
105 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106
107/*
108 * AMD Elan SC520 - Watchdog Timer Registers
109 */
110#define MMCR_BASE 0xfffef000 /* The default base address */
111#define OFFS_WDTMRCTL 0xCB0 /* Watchdog Timer Control Register */
112
113/* WDT Control Register bit definitions */
114#define WDT_EXP_SEL_01 0x0001 /* [01] Time-out = 496 us (with 33 Mhz clk). */
115#define WDT_EXP_SEL_02 0x0002 /* [02] Time-out = 508 ms (with 33 Mhz clk). */
116#define WDT_EXP_SEL_03 0x0004 /* [03] Time-out = 1.02 s (with 33 Mhz clk). */
117#define WDT_EXP_SEL_04 0x0008 /* [04] Time-out = 2.03 s (with 33 Mhz clk). */
118#define WDT_EXP_SEL_05 0x0010 /* [05] Time-out = 4.07 s (with 33 Mhz clk). */
119#define WDT_EXP_SEL_06 0x0020 /* [06] Time-out = 8.13 s (with 33 Mhz clk). */
120#define WDT_EXP_SEL_07 0x0040 /* [07] Time-out = 16.27s (with 33 Mhz clk). */
121#define WDT_EXP_SEL_08 0x0080 /* [08] Time-out = 32.54s (with 33 Mhz clk). */
122#define WDT_IRQ_FLG 0x1000 /* [12] Interrupt Request Flag */
123#define WDT_WRST_ENB 0x4000 /* [14] Watchdog Timer Reset Enable */
124#define WDT_ENB 0x8000 /* [15] Watchdog Timer Enable */
125
126static __u16 __iomem *wdtmrctl;
127
128static void wdt_timer_ping(unsigned long);
Jiri Slaby82eb7c52007-02-08 18:39:36 +0100129static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130static unsigned long next_heartbeat;
131static unsigned long wdt_is_open;
132static char wdt_expect_close;
Alexey Dobriyanc7dfd0c2007-11-01 16:27:08 -0700133static DEFINE_SPINLOCK(wdt_spinlock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134
135/*
136 * Whack the dog
137 */
138
139static void wdt_timer_ping(unsigned long data)
140{
141 /* If we got a heartbeat pulse within the WDT_US_INTERVAL
142 * we agree to ping the WDT
143 */
Alan Coxff948062008-05-19 14:08:44 +0100144 if (time_before(jiffies, next_heartbeat)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145 /* Ping the WDT */
146 spin_lock(&wdt_spinlock);
147 writew(0xAAAA, wdtmrctl);
148 writew(0x5555, wdtmrctl);
149 spin_unlock(&wdt_spinlock);
150
151 /* Re-set the timer interval */
Jiri Slaby82eb7c52007-02-08 18:39:36 +0100152 mod_timer(&timer, jiffies + WDT_INTERVAL);
Alan Coxff948062008-05-19 14:08:44 +0100153 } else
154 printk(KERN_WARNING PFX
155 "Heartbeat lost! Will not ping the watchdog\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156}
157
158/*
159 * Utility routines
160 */
161
162static void wdt_config(int writeval)
163{
164 __u16 dummy;
165 unsigned long flags;
166
167 /* buy some time (ping) */
168 spin_lock_irqsave(&wdt_spinlock, flags);
Alan Coxff948062008-05-19 14:08:44 +0100169 dummy = readw(wdtmrctl); /* ensure write synchronization */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170 writew(0xAAAA, wdtmrctl);
171 writew(0x5555, wdtmrctl);
172 /* unlock WDT = make WDT configuration register writable one time */
173 writew(0x3333, wdtmrctl);
174 writew(0xCCCC, wdtmrctl);
175 /* write WDT configuration register */
176 writew(writeval, wdtmrctl);
177 spin_unlock_irqrestore(&wdt_spinlock, flags);
178}
179
180static int wdt_startup(void)
181{
182 next_heartbeat = jiffies + (timeout * HZ);
183
184 /* Start the timer */
Jiri Slaby82eb7c52007-02-08 18:39:36 +0100185 mod_timer(&timer, jiffies + WDT_INTERVAL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186
187 /* Start the watchdog */
188 wdt_config(WDT_ENB | WDT_WRST_ENB | WDT_EXP_SEL_04);
189
190 printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
191 return 0;
192}
193
194static int wdt_turnoff(void)
195{
196 /* Stop the timer */
197 del_timer(&timer);
198
199 /* Stop the watchdog */
200 wdt_config(0);
201
202 printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
203 return 0;
204}
205
206static int wdt_keepalive(void)
207{
208 /* user land ping */
209 next_heartbeat = jiffies + (timeout * HZ);
210 return 0;
211}
212
213static int wdt_set_heartbeat(int t)
214{
215 if ((t < 1) || (t > 3600)) /* arbitrary upper limit */
216 return -EINVAL;
217
218 timeout = t;
219 return 0;
220}
221
222/*
223 * /dev/watchdog handling
224 */
225
Alan Coxff948062008-05-19 14:08:44 +0100226static ssize_t fop_write(struct file *file, const char __user *buf,
227 size_t count, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228{
229 /* See if we got the magic character 'V' and reload the timer */
Alan Coxff948062008-05-19 14:08:44 +0100230 if (count) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231 if (!nowayout) {
232 size_t ofs;
233
234 /* note: just in case someone wrote the magic character
235 * five months ago... */
236 wdt_expect_close = 0;
237
238 /* now scan */
Alan Coxff948062008-05-19 14:08:44 +0100239 for (ofs = 0; ofs != count; ofs++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 char c;
241 if (get_user(c, buf + ofs))
242 return -EFAULT;
Alan Coxff948062008-05-19 14:08:44 +0100243 if (c == 'V')
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244 wdt_expect_close = 42;
245 }
246 }
247
Alan Coxff948062008-05-19 14:08:44 +0100248 /* Well, anyhow someone wrote to us, we should
249 return that favour */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250 wdt_keepalive();
251 }
252 return count;
253}
254
Alan Coxff948062008-05-19 14:08:44 +0100255static int fop_open(struct inode *inode, struct file *file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 /* Just in case we're already talking to someone... */
Alan Coxff948062008-05-19 14:08:44 +0100258 if (test_and_set_bit(0, &wdt_is_open))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259 return -EBUSY;
260 if (nowayout)
261 __module_get(THIS_MODULE);
262
263 /* Good, fire up the show */
264 wdt_startup();
Wim Van Sebroeck6abe78b2007-07-24 21:38:37 +0000265 return nonseekable_open(inode, file);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266}
267
Alan Coxff948062008-05-19 14:08:44 +0100268static int fop_close(struct inode *inode, struct file *file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269{
Alan Coxff948062008-05-19 14:08:44 +0100270 if (wdt_expect_close == 42)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 wdt_turnoff();
Alan Coxff948062008-05-19 14:08:44 +0100272 else {
273 printk(KERN_CRIT PFX
274 "Unexpected close, not stopping watchdog!\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275 wdt_keepalive();
276 }
277 clear_bit(0, &wdt_is_open);
278 wdt_expect_close = 0;
279 return 0;
280}
281
Alan Cox9b748ed2008-05-19 14:08:49 +0100282static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283{
284 void __user *argp = (void __user *)arg;
285 int __user *p = argp;
Alan Coxff948062008-05-19 14:08:44 +0100286 static const struct watchdog_info ident = {
287 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
288 | WDIOF_MAGICCLOSE,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 .firmware_version = 1,
290 .identity = "SC520",
291 };
292
Wim Van Sebroeck5eb82492008-07-17 18:08:47 +0000293 switch (cmd) {
Alan Coxff948062008-05-19 14:08:44 +0100294 case WDIOC_GETSUPPORT:
295 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
296 case WDIOC_GETSTATUS:
297 case WDIOC_GETBOOTSTATUS:
298 return put_user(0, p);
Alan Coxff948062008-05-19 14:08:44 +0100299 case WDIOC_SETOPTIONS:
300 {
301 int new_options, retval = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302
Alan Coxff948062008-05-19 14:08:44 +0100303 if (get_user(new_options, p))
304 return -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305
Alan Coxff948062008-05-19 14:08:44 +0100306 if (new_options & WDIOS_DISABLECARD) {
307 wdt_turnoff();
308 retval = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310
Alan Coxff948062008-05-19 14:08:44 +0100311 if (new_options & WDIOS_ENABLECARD) {
312 wdt_startup();
313 retval = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314 }
Alan Coxff948062008-05-19 14:08:44 +0100315
316 return retval;
317 }
Wim Van Sebroeck0c060902008-07-18 11:41:17 +0000318 case WDIOC_KEEPALIVE:
319 wdt_keepalive();
320 return 0;
Alan Coxff948062008-05-19 14:08:44 +0100321 case WDIOC_SETTIMEOUT:
322 {
323 int new_timeout;
324
325 if (get_user(new_timeout, p))
326 return -EFAULT;
327
328 if (wdt_set_heartbeat(new_timeout))
329 return -EINVAL;
330
331 wdt_keepalive();
332 /* Fall through */
333 }
334 case WDIOC_GETTIMEOUT:
335 return put_user(timeout, p);
Wim Van Sebroeck0c060902008-07-18 11:41:17 +0000336 default:
337 return -ENOTTY;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338 }
339}
340
Arjan van de Ven62322d22006-07-03 00:24:21 -0700341static const struct file_operations wdt_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 .owner = THIS_MODULE,
343 .llseek = no_llseek,
344 .write = fop_write,
345 .open = fop_open,
346 .release = fop_close,
Alan Cox9b748ed2008-05-19 14:08:49 +0100347 .unlocked_ioctl = fop_ioctl,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348};
349
350static struct miscdevice wdt_miscdev = {
351 .minor = WATCHDOG_MINOR,
352 .name = "watchdog",
353 .fops = &wdt_fops,
354};
355
356/*
357 * Notifier for system down
358 */
359
360static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
361 void *unused)
362{
Alan Coxff948062008-05-19 14:08:44 +0100363 if (code == SYS_DOWN || code == SYS_HALT)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 wdt_turnoff();
365 return NOTIFY_DONE;
366}
367
368/*
369 * The WDT needs to learn about soft shutdowns in order to
370 * turn the timebomb registers off.
371 */
372
373static struct notifier_block wdt_notifier = {
374 .notifier_call = wdt_notify_sys,
375};
376
377static void __exit sc520_wdt_unload(void)
378{
379 if (!nowayout)
380 wdt_turnoff();
381
382 /* Deregister */
383 misc_deregister(&wdt_miscdev);
384 unregister_reboot_notifier(&wdt_notifier);
385 iounmap(wdtmrctl);
386}
387
388static int __init sc520_wdt_init(void)
389{
390 int rc = -EBUSY;
391
Alan Coxff948062008-05-19 14:08:44 +0100392 /* Check that the timeout value is within it's range ;
393 if not reset to the default */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 if (wdt_set_heartbeat(timeout)) {
395 wdt_set_heartbeat(WATCHDOG_TIMEOUT);
Alan Coxff948062008-05-19 14:08:44 +0100396 printk(KERN_INFO PFX
397 "timeout value must be 1 <= timeout <= 3600, using %d\n",
398 WATCHDOG_TIMEOUT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399 }
400
401 wdtmrctl = ioremap((unsigned long)(MMCR_BASE + OFFS_WDTMRCTL), 2);
402 if (!wdtmrctl) {
403 printk(KERN_ERR PFX "Unable to remap memory\n");
404 rc = -ENOMEM;
405 goto err_out_region2;
406 }
407
408 rc = register_reboot_notifier(&wdt_notifier);
409 if (rc) {
Alan Coxff948062008-05-19 14:08:44 +0100410 printk(KERN_ERR PFX
411 "cannot register reboot notifier (err=%d)\n", rc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 goto err_out_ioremap;
413 }
414
415 rc = misc_register(&wdt_miscdev);
416 if (rc) {
Alan Coxff948062008-05-19 14:08:44 +0100417 printk(KERN_ERR PFX
418 "cannot register miscdev on minor=%d (err=%d)\n",
419 WATCHDOG_MINOR, rc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420 goto err_out_notifier;
421 }
422
Alan Coxff948062008-05-19 14:08:44 +0100423 printk(KERN_INFO PFX
424 "WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n",
425 timeout, nowayout);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426
427 return 0;
428
429err_out_notifier:
430 unregister_reboot_notifier(&wdt_notifier);
431err_out_ioremap:
432 iounmap(wdtmrctl);
433err_out_region2:
434 return rc;
435}
436
437module_init(sc520_wdt_init);
438module_exit(sc520_wdt_unload);
439
440MODULE_AUTHOR("Scott and Bill Jennings");
Wim Van Sebroeck143a2e52009-03-18 08:35:09 +0000441MODULE_DESCRIPTION(
442 "Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443MODULE_LICENSE("GPL");
444MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);