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1da177e4 LT |
1 | /* |
2 | * AMD Elan SC520 processor Watchdog Timer driver | |
3 | * | |
4 | * Based on acquirewdt.c by Alan Cox, | |
5 | * and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net> | |
6 | * | |
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 | |
14 | * the hope that it may be useful for others. | |
15 | * | |
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> | |
4e57b681 | 66 | #include <linux/jiffies.h> |
1da177e4 LT |
67 | |
68 | #include <asm/io.h> | |
69 | #include <asm/uaccess.h> | |
70 | #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 */ | |
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) ")"); | |
97 | ||
4bfdf378 | 98 | static int nowayout = WATCHDOG_NOWAYOUT; |
1da177e4 LT |
99 | module_param(nowayout, int, 0); |
100 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)"); | |
101 | ||
102 | /* | |
103 | * AMD Elan SC520 - Watchdog Timer Registers | |
104 | */ | |
105 | #define MMCR_BASE 0xfffef000 /* The default base address */ | |
106 | #define OFFS_WDTMRCTL 0xCB0 /* Watchdog Timer Control Register */ | |
107 | ||
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 */ | |
120 | ||
121 | static __u16 __iomem *wdtmrctl; | |
122 | ||
123 | static void wdt_timer_ping(unsigned long); | |
124 | static struct timer_list timer; | |
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; | |
129 | ||
130 | /* | |
131 | * Whack the dog | |
132 | */ | |
133 | ||
134 | static void wdt_timer_ping(unsigned long data) | |
135 | { | |
136 | /* If we got a heartbeat pulse within the WDT_US_INTERVAL | |
137 | * we agree to ping the WDT | |
138 | */ | |
139 | if(time_before(jiffies, next_heartbeat)) | |
140 | { | |
141 | /* Ping the WDT */ | |
142 | spin_lock(&wdt_spinlock); | |
143 | writew(0xAAAA, wdtmrctl); | |
144 | writew(0x5555, wdtmrctl); | |
145 | spin_unlock(&wdt_spinlock); | |
146 | ||
147 | /* Re-set the timer interval */ | |
148 | timer.expires = jiffies + WDT_INTERVAL; | |
149 | add_timer(&timer); | |
150 | } else { | |
151 | printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n"); | |
152 | } | |
153 | } | |
154 | ||
155 | /* | |
156 | * Utility routines | |
157 | */ | |
158 | ||
159 | static void wdt_config(int writeval) | |
160 | { | |
161 | __u16 dummy; | |
162 | unsigned long flags; | |
163 | ||
164 | /* buy some time (ping) */ | |
165 | spin_lock_irqsave(&wdt_spinlock, flags); | |
166 | dummy=readw(wdtmrctl); /* ensure write synchronization */ | |
167 | writew(0xAAAA, wdtmrctl); | |
168 | writew(0x5555, wdtmrctl); | |
169 | /* unlock WDT = make WDT configuration register writable one time */ | |
170 | writew(0x3333, wdtmrctl); | |
171 | writew(0xCCCC, wdtmrctl); | |
172 | /* write WDT configuration register */ | |
173 | writew(writeval, wdtmrctl); | |
174 | spin_unlock_irqrestore(&wdt_spinlock, flags); | |
175 | } | |
176 | ||
177 | static int wdt_startup(void) | |
178 | { | |
179 | next_heartbeat = jiffies + (timeout * HZ); | |
180 | ||
181 | /* Start the timer */ | |
182 | timer.expires = jiffies + WDT_INTERVAL; | |
183 | add_timer(&timer); | |
184 | ||
185 | /* Start the watchdog */ | |
186 | wdt_config(WDT_ENB | WDT_WRST_ENB | WDT_EXP_SEL_04); | |
187 | ||
188 | printk(KERN_INFO PFX "Watchdog timer is now enabled.\n"); | |
189 | return 0; | |
190 | } | |
191 | ||
192 | static int wdt_turnoff(void) | |
193 | { | |
194 | /* Stop the timer */ | |
195 | del_timer(&timer); | |
196 | ||
197 | /* Stop the watchdog */ | |
198 | wdt_config(0); | |
199 | ||
200 | printk(KERN_INFO PFX "Watchdog timer is now disabled...\n"); | |
201 | return 0; | |
202 | } | |
203 | ||
204 | static int wdt_keepalive(void) | |
205 | { | |
206 | /* user land ping */ | |
207 | next_heartbeat = jiffies + (timeout * HZ); | |
208 | return 0; | |
209 | } | |
210 | ||
211 | static int wdt_set_heartbeat(int t) | |
212 | { | |
213 | if ((t < 1) || (t > 3600)) /* arbitrary upper limit */ | |
214 | return -EINVAL; | |
215 | ||
216 | timeout = t; | |
217 | return 0; | |
218 | } | |
219 | ||
220 | /* | |
221 | * /dev/watchdog handling | |
222 | */ | |
223 | ||
224 | static ssize_t fop_write(struct file * file, const char __user * buf, size_t count, loff_t * ppos) | |
225 | { | |
226 | /* See if we got the magic character 'V' and reload the timer */ | |
227 | if(count) { | |
228 | if (!nowayout) { | |
229 | size_t ofs; | |
230 | ||
231 | /* note: just in case someone wrote the magic character | |
232 | * five months ago... */ | |
233 | wdt_expect_close = 0; | |
234 | ||
235 | /* now scan */ | |
236 | for(ofs = 0; ofs != count; ofs++) { | |
237 | char c; | |
238 | if (get_user(c, buf + ofs)) | |
239 | return -EFAULT; | |
240 | if(c == 'V') | |
241 | wdt_expect_close = 42; | |
242 | } | |
243 | } | |
244 | ||
245 | /* Well, anyhow someone wrote to us, we should return that favour */ | |
246 | wdt_keepalive(); | |
247 | } | |
248 | return count; | |
249 | } | |
250 | ||
251 | static int fop_open(struct inode * inode, struct file * file) | |
252 | { | |
253 | nonseekable_open(inode, file); | |
254 | ||
255 | /* Just in case we're already talking to someone... */ | |
256 | if(test_and_set_bit(0, &wdt_is_open)) | |
257 | return -EBUSY; | |
258 | if (nowayout) | |
259 | __module_get(THIS_MODULE); | |
260 | ||
261 | /* Good, fire up the show */ | |
262 | wdt_startup(); | |
263 | return 0; | |
264 | } | |
265 | ||
266 | static int fop_close(struct inode * inode, struct file * file) | |
267 | { | |
268 | if(wdt_expect_close == 42) { | |
269 | wdt_turnoff(); | |
270 | } else { | |
271 | printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n"); | |
272 | wdt_keepalive(); | |
273 | } | |
274 | clear_bit(0, &wdt_is_open); | |
275 | wdt_expect_close = 0; | |
276 | return 0; | |
277 | } | |
278 | ||
279 | static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd, | |
280 | unsigned long arg) | |
281 | { | |
282 | void __user *argp = (void __user *)arg; | |
283 | int __user *p = argp; | |
284 | static struct watchdog_info ident = { | |
285 | .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, | |
286 | .firmware_version = 1, | |
287 | .identity = "SC520", | |
288 | }; | |
289 | ||
290 | switch(cmd) | |
291 | { | |
292 | default: | |
293 | return -ENOIOCTLCMD; | |
294 | 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); | |
299 | case WDIOC_KEEPALIVE: | |
300 | wdt_keepalive(); | |
301 | return 0; | |
302 | case WDIOC_SETOPTIONS: | |
303 | { | |
304 | int new_options, retval = -EINVAL; | |
305 | ||
306 | if(get_user(new_options, p)) | |
307 | return -EFAULT; | |
308 | ||
309 | if(new_options & WDIOS_DISABLECARD) { | |
310 | wdt_turnoff(); | |
311 | retval = 0; | |
312 | } | |
313 | ||
314 | if(new_options & WDIOS_ENABLECARD) { | |
315 | wdt_startup(); | |
316 | retval = 0; | |
317 | } | |
318 | ||
319 | return retval; | |
320 | } | |
321 | 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); | |
336 | } | |
337 | } | |
338 | ||
62322d25 | 339 | static const struct file_operations wdt_fops = { |
1da177e4 LT |
340 | .owner = THIS_MODULE, |
341 | .llseek = no_llseek, | |
342 | .write = fop_write, | |
343 | .open = fop_open, | |
344 | .release = fop_close, | |
345 | .ioctl = fop_ioctl, | |
346 | }; | |
347 | ||
348 | static struct miscdevice wdt_miscdev = { | |
349 | .minor = WATCHDOG_MINOR, | |
350 | .name = "watchdog", | |
351 | .fops = &wdt_fops, | |
352 | }; | |
353 | ||
354 | /* | |
355 | * Notifier for system down | |
356 | */ | |
357 | ||
358 | static int wdt_notify_sys(struct notifier_block *this, unsigned long code, | |
359 | void *unused) | |
360 | { | |
361 | if(code==SYS_DOWN || code==SYS_HALT) | |
362 | wdt_turnoff(); | |
363 | return NOTIFY_DONE; | |
364 | } | |
365 | ||
366 | /* | |
367 | * The WDT needs to learn about soft shutdowns in order to | |
368 | * turn the timebomb registers off. | |
369 | */ | |
370 | ||
371 | static struct notifier_block wdt_notifier = { | |
372 | .notifier_call = wdt_notify_sys, | |
373 | }; | |
374 | ||
375 | static void __exit sc520_wdt_unload(void) | |
376 | { | |
377 | if (!nowayout) | |
378 | wdt_turnoff(); | |
379 | ||
380 | /* Deregister */ | |
381 | misc_deregister(&wdt_miscdev); | |
382 | unregister_reboot_notifier(&wdt_notifier); | |
383 | iounmap(wdtmrctl); | |
384 | } | |
385 | ||
386 | static int __init sc520_wdt_init(void) | |
387 | { | |
388 | int rc = -EBUSY; | |
389 | ||
390 | spin_lock_init(&wdt_spinlock); | |
391 | ||
392 | init_timer(&timer); | |
393 | timer.function = wdt_timer_ping; | |
394 | timer.data = 0; | |
395 | ||
396 | /* Check that the timeout value is within it's range ; if not reset to the default */ | |
397 | if (wdt_set_heartbeat(timeout)) { | |
398 | wdt_set_heartbeat(WATCHDOG_TIMEOUT); | |
399 | printk(KERN_INFO PFX "timeout value must be 1<=timeout<=3600, using %d\n", | |
400 | WATCHDOG_TIMEOUT); | |
401 | } | |
402 | ||
403 | wdtmrctl = ioremap((unsigned long)(MMCR_BASE + OFFS_WDTMRCTL), 2); | |
404 | if (!wdtmrctl) { | |
405 | printk(KERN_ERR PFX "Unable to remap memory\n"); | |
406 | rc = -ENOMEM; | |
407 | goto err_out_region2; | |
408 | } | |
409 | ||
410 | rc = register_reboot_notifier(&wdt_notifier); | |
411 | if (rc) { | |
412 | printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n", | |
413 | rc); | |
414 | goto err_out_ioremap; | |
415 | } | |
416 | ||
417 | rc = misc_register(&wdt_miscdev); | |
418 | if (rc) { | |
419 | printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n", | |
420 | WATCHDOG_MINOR, rc); | |
421 | goto err_out_notifier; | |
422 | } | |
423 | ||
424 | printk(KERN_INFO PFX "WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n", | |
425 | timeout,nowayout); | |
426 | ||
427 | return 0; | |
428 | ||
429 | err_out_notifier: | |
430 | unregister_reboot_notifier(&wdt_notifier); | |
431 | err_out_ioremap: | |
432 | iounmap(wdtmrctl); | |
433 | err_out_region2: | |
434 | return rc; | |
435 | } | |
436 | ||
437 | module_init(sc520_wdt_init); | |
438 | module_exit(sc520_wdt_unload); | |
439 | ||
440 | MODULE_AUTHOR("Scott and Bill Jennings"); | |
441 | MODULE_DESCRIPTION("Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor"); | |
442 | MODULE_LICENSE("GPL"); | |
443 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |