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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
Joe Perches27c766a2012-02-15 15:06:19 -080055#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
56
Linus Torvalds1da177e2005-04-16 15:20:36 -070057#include <linux/module.h>
58#include <linux/moduleparam.h>
59#include <linux/types.h>
60#include <linux/timer.h>
61#include <linux/miscdevice.h>
62#include <linux/watchdog.h>
63#include <linux/fs.h>
64#include <linux/ioport.h>
65#include <linux/notifier.h>
66#include <linux/reboot.h>
67#include <linux/init.h>
Tim Schmielau4e57b682005-10-30 15:03:48 -080068#include <linux/jiffies.h>
Alan Coxff948062008-05-19 14:08:44 +010069#include <linux/io.h>
70#include <linux/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070071
Linus Torvalds1da177e2005-04-16 15:20:36 -070072
Linus Torvalds1da177e2005-04-16 15:20:36 -070073/*
74 * The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7)
75 *
76 * 0: 492us 2: 1.01s 4: 4.03s 6: 16.22s
77 * 1: 503ms 3: 2.01s 5: 8.05s 7: 32.21s
78 *
79 * We will program the SC520 watchdog for a timeout of 2.01s.
80 * If we reset the watchdog every ~250ms we should be safe.
81 */
82
83#define WDT_INTERVAL (HZ/4+1)
84
85/*
86 * We must not require too good response from the userspace daemon.
87 * Here we require the userspace daemon to send us a heartbeat
88 * char to /dev/watchdog every 30 seconds.
89 */
90
91#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
Alan Coxff948062008-05-19 14:08:44 +010092/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
93static int timeout = WATCHDOG_TIMEOUT;
Linus Torvalds1da177e2005-04-16 15:20:36 -070094module_param(timeout, int, 0);
Alan Coxff948062008-05-19 14:08:44 +010095MODULE_PARM_DESC(timeout,
96 "Watchdog timeout in seconds. (1 <= timeout <= 3600, default="
97 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
Linus Torvalds1da177e2005-04-16 15:20:36 -070098
Wim Van Sebroeck86a1e182012-03-05 16:51:11 +010099static bool nowayout = WATCHDOG_NOWAYOUT;
100module_param(nowayout, bool, 0);
Alan Coxff948062008-05-19 14:08:44 +0100101MODULE_PARM_DESC(nowayout,
102 "Watchdog cannot be stopped once started (default="
103 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104
105/*
106 * AMD Elan SC520 - Watchdog Timer Registers
107 */
108#define MMCR_BASE 0xfffef000 /* The default base address */
109#define OFFS_WDTMRCTL 0xCB0 /* Watchdog Timer Control Register */
110
111/* WDT Control Register bit definitions */
112#define WDT_EXP_SEL_01 0x0001 /* [01] Time-out = 496 us (with 33 Mhz clk). */
113#define WDT_EXP_SEL_02 0x0002 /* [02] Time-out = 508 ms (with 33 Mhz clk). */
114#define WDT_EXP_SEL_03 0x0004 /* [03] Time-out = 1.02 s (with 33 Mhz clk). */
115#define WDT_EXP_SEL_04 0x0008 /* [04] Time-out = 2.03 s (with 33 Mhz clk). */
116#define WDT_EXP_SEL_05 0x0010 /* [05] Time-out = 4.07 s (with 33 Mhz clk). */
117#define WDT_EXP_SEL_06 0x0020 /* [06] Time-out = 8.13 s (with 33 Mhz clk). */
118#define WDT_EXP_SEL_07 0x0040 /* [07] Time-out = 16.27s (with 33 Mhz clk). */
119#define WDT_EXP_SEL_08 0x0080 /* [08] Time-out = 32.54s (with 33 Mhz clk). */
120#define WDT_IRQ_FLG 0x1000 /* [12] Interrupt Request Flag */
121#define WDT_WRST_ENB 0x4000 /* [14] Watchdog Timer Reset Enable */
122#define WDT_ENB 0x8000 /* [15] Watchdog Timer Enable */
123
124static __u16 __iomem *wdtmrctl;
125
126static void wdt_timer_ping(unsigned long);
Jiri Slaby82eb7c52007-02-08 18:39:36 +0100127static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128static unsigned long next_heartbeat;
129static unsigned long wdt_is_open;
130static char wdt_expect_close;
Alexey Dobriyanc7dfd0c2007-11-01 16:27:08 -0700131static DEFINE_SPINLOCK(wdt_spinlock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132
133/*
134 * Whack the dog
135 */
136
137static void wdt_timer_ping(unsigned long data)
138{
139 /* If we got a heartbeat pulse within the WDT_US_INTERVAL
140 * we agree to ping the WDT
141 */
Alan Coxff948062008-05-19 14:08:44 +0100142 if (time_before(jiffies, next_heartbeat)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 /* Ping the WDT */
144 spin_lock(&wdt_spinlock);
145 writew(0xAAAA, wdtmrctl);
146 writew(0x5555, wdtmrctl);
147 spin_unlock(&wdt_spinlock);
148
149 /* Re-set the timer interval */
Jiri Slaby82eb7c52007-02-08 18:39:36 +0100150 mod_timer(&timer, jiffies + WDT_INTERVAL);
Alan Coxff948062008-05-19 14:08:44 +0100151 } else
Joe Perches27c766a2012-02-15 15:06:19 -0800152 pr_warn("Heartbeat lost! Will not ping the watchdog\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153}
154
155/*
156 * Utility routines
157 */
158
159static void wdt_config(int writeval)
160{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 unsigned long flags;
162
163 /* buy some time (ping) */
164 spin_lock_irqsave(&wdt_spinlock, flags);
Alexander Shiyana9ba8372014-02-15 13:22:49 +0400165 readw(wdtmrctl); /* ensure write synchronization */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 writew(0xAAAA, wdtmrctl);
167 writew(0x5555, wdtmrctl);
168 /* unlock WDT = make WDT configuration register writable one time */
169 writew(0x3333, wdtmrctl);
170 writew(0xCCCC, wdtmrctl);
171 /* write WDT configuration register */
172 writew(writeval, wdtmrctl);
173 spin_unlock_irqrestore(&wdt_spinlock, flags);
174}
175
176static int wdt_startup(void)
177{
178 next_heartbeat = jiffies + (timeout * HZ);
179
180 /* Start the timer */
Jiri Slaby82eb7c52007-02-08 18:39:36 +0100181 mod_timer(&timer, jiffies + WDT_INTERVAL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182
183 /* Start the watchdog */
184 wdt_config(WDT_ENB | WDT_WRST_ENB | WDT_EXP_SEL_04);
185
Joe Perches27c766a2012-02-15 15:06:19 -0800186 pr_info("Watchdog timer is now enabled\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 return 0;
188}
189
190static int wdt_turnoff(void)
191{
192 /* Stop the timer */
193 del_timer(&timer);
194
195 /* Stop the watchdog */
196 wdt_config(0);
197
Joe Perches27c766a2012-02-15 15:06:19 -0800198 pr_info("Watchdog timer is now disabled...\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199 return 0;
200}
201
202static int wdt_keepalive(void)
203{
204 /* user land ping */
205 next_heartbeat = jiffies + (timeout * HZ);
206 return 0;
207}
208
209static int wdt_set_heartbeat(int t)
210{
211 if ((t < 1) || (t > 3600)) /* arbitrary upper limit */
212 return -EINVAL;
213
214 timeout = t;
215 return 0;
216}
217
218/*
219 * /dev/watchdog handling
220 */
221
Alan Coxff948062008-05-19 14:08:44 +0100222static ssize_t fop_write(struct file *file, const char __user *buf,
223 size_t count, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224{
225 /* See if we got the magic character 'V' and reload the timer */
Alan Coxff948062008-05-19 14:08:44 +0100226 if (count) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 if (!nowayout) {
228 size_t ofs;
229
230 /* note: just in case someone wrote the magic character
231 * five months ago... */
232 wdt_expect_close = 0;
233
234 /* now scan */
Alan Coxff948062008-05-19 14:08:44 +0100235 for (ofs = 0; ofs != count; ofs++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236 char c;
237 if (get_user(c, buf + ofs))
238 return -EFAULT;
Alan Coxff948062008-05-19 14:08:44 +0100239 if (c == 'V')
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 wdt_expect_close = 42;
241 }
242 }
243
Alan Coxff948062008-05-19 14:08:44 +0100244 /* Well, anyhow someone wrote to us, we should
245 return that favour */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246 wdt_keepalive();
247 }
248 return count;
249}
250
Alan Coxff948062008-05-19 14:08:44 +0100251static int fop_open(struct inode *inode, struct file *file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253 /* Just in case we're already talking to someone... */
Alan Coxff948062008-05-19 14:08:44 +0100254 if (test_and_set_bit(0, &wdt_is_open))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255 return -EBUSY;
256 if (nowayout)
257 __module_get(THIS_MODULE);
258
259 /* Good, fire up the show */
260 wdt_startup();
Wim Van Sebroeck6abe78b2007-07-24 21:38:37 +0000261 return nonseekable_open(inode, file);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262}
263
Alan Coxff948062008-05-19 14:08:44 +0100264static int fop_close(struct inode *inode, struct file *file)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265{
Alan Coxff948062008-05-19 14:08:44 +0100266 if (wdt_expect_close == 42)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 wdt_turnoff();
Alan Coxff948062008-05-19 14:08:44 +0100268 else {
Joe Perches27c766a2012-02-15 15:06:19 -0800269 pr_crit("Unexpected close, not stopping watchdog!\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270 wdt_keepalive();
271 }
272 clear_bit(0, &wdt_is_open);
273 wdt_expect_close = 0;
274 return 0;
275}
276
Alan Cox9b748ed2008-05-19 14:08:49 +0100277static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278{
279 void __user *argp = (void __user *)arg;
280 int __user *p = argp;
Alan Coxff948062008-05-19 14:08:44 +0100281 static const struct watchdog_info ident = {
282 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
283 | WDIOF_MAGICCLOSE,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 .firmware_version = 1,
285 .identity = "SC520",
286 };
287
Wim Van Sebroeck5eb82492008-07-17 18:08:47 +0000288 switch (cmd) {
Alan Coxff948062008-05-19 14:08:44 +0100289 case WDIOC_GETSUPPORT:
290 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
291 case WDIOC_GETSTATUS:
292 case WDIOC_GETBOOTSTATUS:
293 return put_user(0, p);
Alan Coxff948062008-05-19 14:08:44 +0100294 case WDIOC_SETOPTIONS:
295 {
296 int new_options, retval = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297
Alan Coxff948062008-05-19 14:08:44 +0100298 if (get_user(new_options, p))
299 return -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300
Alan Coxff948062008-05-19 14:08:44 +0100301 if (new_options & WDIOS_DISABLECARD) {
302 wdt_turnoff();
303 retval = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305
Alan Coxff948062008-05-19 14:08:44 +0100306 if (new_options & WDIOS_ENABLECARD) {
307 wdt_startup();
308 retval = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309 }
Alan Coxff948062008-05-19 14:08:44 +0100310
311 return retval;
312 }
Wim Van Sebroeck0c06090c2008-07-18 11:41:17 +0000313 case WDIOC_KEEPALIVE:
314 wdt_keepalive();
315 return 0;
Alan Coxff948062008-05-19 14:08:44 +0100316 case WDIOC_SETTIMEOUT:
317 {
318 int new_timeout;
319
320 if (get_user(new_timeout, p))
321 return -EFAULT;
322
323 if (wdt_set_heartbeat(new_timeout))
324 return -EINVAL;
325
326 wdt_keepalive();
327 /* Fall through */
328 }
329 case WDIOC_GETTIMEOUT:
330 return put_user(timeout, p);
Wim Van Sebroeck0c06090c2008-07-18 11:41:17 +0000331 default:
332 return -ENOTTY;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 }
334}
335
Arjan van de Ven62322d22006-07-03 00:24:21 -0700336static const struct file_operations wdt_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 .owner = THIS_MODULE,
338 .llseek = no_llseek,
339 .write = fop_write,
340 .open = fop_open,
341 .release = fop_close,
Alan Cox9b748ed2008-05-19 14:08:49 +0100342 .unlocked_ioctl = fop_ioctl,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343};
344
345static struct miscdevice wdt_miscdev = {
346 .minor = WATCHDOG_MINOR,
347 .name = "watchdog",
348 .fops = &wdt_fops,
349};
350
351/*
352 * Notifier for system down
353 */
354
355static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
356 void *unused)
357{
Alan Coxff948062008-05-19 14:08:44 +0100358 if (code == SYS_DOWN || code == SYS_HALT)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 wdt_turnoff();
360 return NOTIFY_DONE;
361}
362
363/*
364 * The WDT needs to learn about soft shutdowns in order to
365 * turn the timebomb registers off.
366 */
367
368static struct notifier_block wdt_notifier = {
369 .notifier_call = wdt_notify_sys,
370};
371
372static void __exit sc520_wdt_unload(void)
373{
374 if (!nowayout)
375 wdt_turnoff();
376
377 /* Deregister */
378 misc_deregister(&wdt_miscdev);
379 unregister_reboot_notifier(&wdt_notifier);
380 iounmap(wdtmrctl);
381}
382
383static int __init sc520_wdt_init(void)
384{
385 int rc = -EBUSY;
386
Alan Coxff948062008-05-19 14:08:44 +0100387 /* Check that the timeout value is within it's range ;
388 if not reset to the default */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 if (wdt_set_heartbeat(timeout)) {
390 wdt_set_heartbeat(WATCHDOG_TIMEOUT);
Joe Perches27c766a2012-02-15 15:06:19 -0800391 pr_info("timeout value must be 1 <= timeout <= 3600, using %d\n",
392 WATCHDOG_TIMEOUT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393 }
394
Sean Youngcef153a2011-08-23 22:30:09 +0100395 wdtmrctl = ioremap(MMCR_BASE + OFFS_WDTMRCTL, 2);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396 if (!wdtmrctl) {
Joe Perches27c766a2012-02-15 15:06:19 -0800397 pr_err("Unable to remap memory\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398 rc = -ENOMEM;
399 goto err_out_region2;
400 }
401
402 rc = register_reboot_notifier(&wdt_notifier);
403 if (rc) {
Joe Perches27c766a2012-02-15 15:06:19 -0800404 pr_err("cannot register reboot notifier (err=%d)\n", rc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 goto err_out_ioremap;
406 }
407
408 rc = misc_register(&wdt_miscdev);
409 if (rc) {
Joe Perches27c766a2012-02-15 15:06:19 -0800410 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
411 WATCHDOG_MINOR, rc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 goto err_out_notifier;
413 }
414
Joe Perches27c766a2012-02-15 15:06:19 -0800415 pr_info("WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n",
416 timeout, nowayout);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417
418 return 0;
419
420err_out_notifier:
421 unregister_reboot_notifier(&wdt_notifier);
422err_out_ioremap:
423 iounmap(wdtmrctl);
424err_out_region2:
425 return rc;
426}
427
428module_init(sc520_wdt_init);
429module_exit(sc520_wdt_unload);
430
431MODULE_AUTHOR("Scott and Bill Jennings");
Wim Van Sebroeck143a2e52009-03-18 08:35:09 +0000432MODULE_DESCRIPTION(
433 "Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434MODULE_LICENSE("GPL");