2 * AMD Elan SC520 processor Watchdog Timer driver
4 * Based on acquirewdt.c by Alan Cox,
5 * and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
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.
12 * The authors do NOT admit liability nor provide warranty for
13 * any of this software. This material is provided "AS-IS" in
14 * the hope that it may be useful for others.
16 * (c) Copyright 2001 Scott Jennings <linuxdrivers@oro.net>
17 * 9/27 - 2001 [Initial release]
19 * Additional fixes Alan Cox
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>
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
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
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.
52 * This driver uses memory mapped IO, and spinlock.
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>
62 #include <linux/ioport.h>
63 #include <linux/notifier.h>
64 #include <linux/reboot.h>
65 #include <linux/init.h>
66 #include <linux/jiffies.h>
69 #include <asm/uaccess.h>
70 #include <asm/system.h>
72 #define OUR_NAME "sc520_wdt"
73 #define PFX OUR_NAME ": "
76 * The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7)
78 * 0: 492us 2: 1.01s 4: 4.03s 6: 16.22s
79 * 1: 503ms 3: 2.01s 5: 8.05s 7: 32.21s
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.
85 #define WDT_INTERVAL (HZ/4+1)
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.
93 #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
94 static int timeout
= WATCHDOG_TIMEOUT
; /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
95 module_param(timeout
, int, 0);
96 MODULE_PARM_DESC(timeout
, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT
) ")");
98 static int nowayout
= WATCHDOG_NOWAYOUT
;
99 module_param(nowayout
, int, 0);
100 MODULE_PARM_DESC(nowayout
, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT
) ")");
103 * AMD Elan SC520 - Watchdog Timer Registers
105 #define MMCR_BASE 0xfffef000 /* The default base address */
106 #define OFFS_WDTMRCTL 0xCB0 /* Watchdog Timer Control Register */
108 /* WDT Control Register bit definitions */
109 #define WDT_EXP_SEL_01 0x0001 /* [01] Time-out = 496 us (with 33 Mhz clk). */
110 #define WDT_EXP_SEL_02 0x0002 /* [02] Time-out = 508 ms (with 33 Mhz clk). */
111 #define WDT_EXP_SEL_03 0x0004 /* [03] Time-out = 1.02 s (with 33 Mhz clk). */
112 #define WDT_EXP_SEL_04 0x0008 /* [04] Time-out = 2.03 s (with 33 Mhz clk). */
113 #define WDT_EXP_SEL_05 0x0010 /* [05] Time-out = 4.07 s (with 33 Mhz clk). */
114 #define WDT_EXP_SEL_06 0x0020 /* [06] Time-out = 8.13 s (with 33 Mhz clk). */
115 #define WDT_EXP_SEL_07 0x0040 /* [07] Time-out = 16.27s (with 33 Mhz clk). */
116 #define WDT_EXP_SEL_08 0x0080 /* [08] Time-out = 32.54s (with 33 Mhz clk). */
117 #define WDT_IRQ_FLG 0x1000 /* [12] Interrupt Request Flag */
118 #define WDT_WRST_ENB 0x4000 /* [14] Watchdog Timer Reset Enable */
119 #define WDT_ENB 0x8000 /* [15] Watchdog Timer Enable */
121 static __u16 __iomem
*wdtmrctl
;
123 static void wdt_timer_ping(unsigned long);
124 static DEFINE_TIMER(timer
, wdt_timer_ping
, 0, 0);
125 static unsigned long next_heartbeat
;
126 static unsigned long wdt_is_open
;
127 static char wdt_expect_close
;
128 static spinlock_t wdt_spinlock
;
134 static void wdt_timer_ping(unsigned long data
)
136 /* If we got a heartbeat pulse within the WDT_US_INTERVAL
137 * we agree to ping the WDT
139 if(time_before(jiffies
, next_heartbeat
))
142 spin_lock(&wdt_spinlock
);
143 writew(0xAAAA, wdtmrctl
);
144 writew(0x5555, wdtmrctl
);
145 spin_unlock(&wdt_spinlock
);
147 /* Re-set the timer interval */
148 mod_timer(&timer
, jiffies
+ WDT_INTERVAL
);
150 printk(KERN_WARNING PFX
"Heartbeat lost! Will not ping the watchdog\n");
158 static void wdt_config(int writeval
)
163 /* buy some time (ping) */
164 spin_lock_irqsave(&wdt_spinlock
, flags
);
165 dummy
=readw(wdtmrctl
); /* ensure write synchronization */
166 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
);
176 static int wdt_startup(void)
178 next_heartbeat
= jiffies
+ (timeout
* HZ
);
180 /* Start the timer */
181 mod_timer(&timer
, jiffies
+ WDT_INTERVAL
);
183 /* Start the watchdog */
184 wdt_config(WDT_ENB
| WDT_WRST_ENB
| WDT_EXP_SEL_04
);
186 printk(KERN_INFO PFX
"Watchdog timer is now enabled.\n");
190 static int wdt_turnoff(void)
195 /* Stop the watchdog */
198 printk(KERN_INFO PFX
"Watchdog timer is now disabled...\n");
202 static int wdt_keepalive(void)
205 next_heartbeat
= jiffies
+ (timeout
* HZ
);
209 static int wdt_set_heartbeat(int t
)
211 if ((t
< 1) || (t
> 3600)) /* arbitrary upper limit */
219 * /dev/watchdog handling
222 static ssize_t
fop_write(struct file
* file
, const char __user
* buf
, size_t count
, loff_t
* ppos
)
224 /* See if we got the magic character 'V' and reload the timer */
229 /* note: just in case someone wrote the magic character
230 * five months ago... */
231 wdt_expect_close
= 0;
234 for(ofs
= 0; ofs
!= count
; ofs
++) {
236 if (get_user(c
, buf
+ ofs
))
239 wdt_expect_close
= 42;
243 /* Well, anyhow someone wrote to us, we should return that favour */
249 static int fop_open(struct inode
* inode
, struct file
* file
)
251 /* Just in case we're already talking to someone... */
252 if(test_and_set_bit(0, &wdt_is_open
))
255 __module_get(THIS_MODULE
);
257 /* Good, fire up the show */
259 return nonseekable_open(inode
, file
);
262 static int fop_close(struct inode
* inode
, struct file
* file
)
264 if(wdt_expect_close
== 42) {
267 printk(KERN_CRIT PFX
"Unexpected close, not stopping watchdog!\n");
270 clear_bit(0, &wdt_is_open
);
271 wdt_expect_close
= 0;
275 static int fop_ioctl(struct inode
*inode
, struct file
*file
, unsigned int cmd
,
278 void __user
*argp
= (void __user
*)arg
;
279 int __user
*p
= argp
;
280 static struct watchdog_info ident
= {
281 .options
= WDIOF_KEEPALIVEPING
| WDIOF_SETTIMEOUT
| WDIOF_MAGICCLOSE
,
282 .firmware_version
= 1,
290 case WDIOC_GETSUPPORT
:
291 return copy_to_user(argp
, &ident
, sizeof(ident
))?-EFAULT
:0;
292 case WDIOC_GETSTATUS
:
293 case WDIOC_GETBOOTSTATUS
:
294 return put_user(0, p
);
295 case WDIOC_KEEPALIVE
:
298 case WDIOC_SETOPTIONS
:
300 int new_options
, retval
= -EINVAL
;
302 if(get_user(new_options
, p
))
305 if(new_options
& WDIOS_DISABLECARD
) {
310 if(new_options
& WDIOS_ENABLECARD
) {
317 case WDIOC_SETTIMEOUT
:
321 if(get_user(new_timeout
, p
))
324 if(wdt_set_heartbeat(new_timeout
))
330 case WDIOC_GETTIMEOUT
:
331 return put_user(timeout
, p
);
335 static const struct file_operations wdt_fops
= {
336 .owner
= THIS_MODULE
,
340 .release
= fop_close
,
344 static struct miscdevice wdt_miscdev
= {
345 .minor
= WATCHDOG_MINOR
,
351 * Notifier for system down
354 static int wdt_notify_sys(struct notifier_block
*this, unsigned long code
,
357 if(code
==SYS_DOWN
|| code
==SYS_HALT
)
363 * The WDT needs to learn about soft shutdowns in order to
364 * turn the timebomb registers off.
367 static struct notifier_block wdt_notifier
= {
368 .notifier_call
= wdt_notify_sys
,
371 static void __exit
sc520_wdt_unload(void)
377 misc_deregister(&wdt_miscdev
);
378 unregister_reboot_notifier(&wdt_notifier
);
382 static int __init
sc520_wdt_init(void)
386 spin_lock_init(&wdt_spinlock
);
388 /* Check that the timeout value is within it's range ; if not reset to the default */
389 if (wdt_set_heartbeat(timeout
)) {
390 wdt_set_heartbeat(WATCHDOG_TIMEOUT
);
391 printk(KERN_INFO PFX
"timeout value must be 1<=timeout<=3600, using %d\n",
395 wdtmrctl
= ioremap((unsigned long)(MMCR_BASE
+ OFFS_WDTMRCTL
), 2);
397 printk(KERN_ERR PFX
"Unable to remap memory\n");
399 goto err_out_region2
;
402 rc
= register_reboot_notifier(&wdt_notifier
);
404 printk(KERN_ERR PFX
"cannot register reboot notifier (err=%d)\n",
406 goto err_out_ioremap
;
409 rc
= misc_register(&wdt_miscdev
);
411 printk(KERN_ERR PFX
"cannot register miscdev on minor=%d (err=%d)\n",
413 goto err_out_notifier
;
416 printk(KERN_INFO PFX
"WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n",
422 unregister_reboot_notifier(&wdt_notifier
);
429 module_init(sc520_wdt_init
);
430 module_exit(sc520_wdt_unload
);
432 MODULE_AUTHOR("Scott and Bill Jennings");
433 MODULE_DESCRIPTION("Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor");
434 MODULE_LICENSE("GPL");
435 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR
);