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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 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
56 | |
57 | #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> |
68 | #include <linux/jiffies.h> |
69 | #include <linux/io.h> |
70 | #include <linux/uaccess.h> |
71 | |
72 | |
73 | /* |
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 */ |
92 | /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */ |
93 | static int timeout = WATCHDOG_TIMEOUT; |
94 | module_param(timeout, int, 0); |
95 | MODULE_PARM_DESC(timeout, |
96 | "Watchdog timeout in seconds. (1 <= timeout <= 3600, default=" |
97 | __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); |
98 | |
99 | static bool nowayout = WATCHDOG_NOWAYOUT; |
100 | module_param(nowayout, bool, 0); |
101 | MODULE_PARM_DESC(nowayout, |
102 | "Watchdog cannot be stopped once started (default=" |
103 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
104 | |
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 | |
124 | static __u16 __iomem *wdtmrctl; |
125 | |
126 | static void wdt_timer_ping(unsigned long); |
127 | static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0); |
128 | static unsigned long next_heartbeat; |
129 | static unsigned long wdt_is_open; |
130 | static char wdt_expect_close; |
131 | static DEFINE_SPINLOCK(wdt_spinlock); |
132 | |
133 | /* |
134 | * Whack the dog |
135 | */ |
136 | |
137 | static 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 | */ |
142 | if (time_before(jiffies, next_heartbeat)) { |
143 | /* 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 */ |
150 | mod_timer(&timer, jiffies + WDT_INTERVAL); |
151 | } else |
152 | pr_warn("Heartbeat lost! Will not ping the watchdog\n"); |
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 | mod_timer(&timer, jiffies + WDT_INTERVAL); |
183 | |
184 | /* Start the watchdog */ |
185 | wdt_config(WDT_ENB | WDT_WRST_ENB | WDT_EXP_SEL_04); |
186 | |
187 | pr_info("Watchdog timer is now enabled\n"); |
188 | return 0; |
189 | } |
190 | |
191 | static int wdt_turnoff(void) |
192 | { |
193 | /* Stop the timer */ |
194 | del_timer(&timer); |
195 | |
196 | /* Stop the watchdog */ |
197 | wdt_config(0); |
198 | |
199 | pr_info("Watchdog timer is now disabled...\n"); |
200 | return 0; |
201 | } |
202 | |
203 | static int wdt_keepalive(void) |
204 | { |
205 | /* user land ping */ |
206 | next_heartbeat = jiffies + (timeout * HZ); |
207 | return 0; |
208 | } |
209 | |
210 | static int wdt_set_heartbeat(int t) |
211 | { |
212 | if ((t < 1) || (t > 3600)) /* arbitrary upper limit */ |
213 | return -EINVAL; |
214 | |
215 | timeout = t; |
216 | return 0; |
217 | } |
218 | |
219 | /* |
220 | * /dev/watchdog handling |
221 | */ |
222 | |
223 | static ssize_t fop_write(struct file *file, const char __user *buf, |
224 | 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 |
246 | return that favour */ |
247 | wdt_keepalive(); |
248 | } |
249 | return count; |
250 | } |
251 | |
252 | static int fop_open(struct inode *inode, struct file *file) |
253 | { |
254 | /* Just in case we're already talking to someone... */ |
255 | if (test_and_set_bit(0, &wdt_is_open)) |
256 | return -EBUSY; |
257 | if (nowayout) |
258 | __module_get(THIS_MODULE); |
259 | |
260 | /* Good, fire up the show */ |
261 | wdt_startup(); |
262 | return nonseekable_open(inode, file); |
263 | } |
264 | |
265 | static int fop_close(struct inode *inode, struct file *file) |
266 | { |
267 | if (wdt_expect_close == 42) |
268 | wdt_turnoff(); |
269 | else { |
270 | pr_crit("Unexpected close, not stopping watchdog!\n"); |
271 | wdt_keepalive(); |
272 | } |
273 | clear_bit(0, &wdt_is_open); |
274 | wdt_expect_close = 0; |
275 | return 0; |
276 | } |
277 | |
278 | static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg) |
279 | { |
280 | void __user *argp = (void __user *)arg; |
281 | int __user *p = argp; |
282 | static const struct watchdog_info ident = { |
283 | .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
284 | | WDIOF_MAGICCLOSE, |
285 | .firmware_version = 1, |
286 | .identity = "SC520", |
287 | }; |
288 | |
289 | switch (cmd) { |
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_SETOPTIONS: |
296 | { |
297 | int new_options, retval = -EINVAL; |
298 | |
299 | if (get_user(new_options, p)) |
300 | return -EFAULT; |
301 | |
302 | if (new_options & WDIOS_DISABLECARD) { |
303 | wdt_turnoff(); |
304 | retval = 0; |
305 | } |
306 | |
307 | if (new_options & WDIOS_ENABLECARD) { |
308 | wdt_startup(); |
309 | retval = 0; |
310 | } |
311 | |
312 | return retval; |
313 | } |
314 | case WDIOC_KEEPALIVE: |
315 | wdt_keepalive(); |
316 | return 0; |
317 | case WDIOC_SETTIMEOUT: |
318 | { |
319 | int new_timeout; |
320 | |
321 | if (get_user(new_timeout, p)) |
322 | return -EFAULT; |
323 | |
324 | if (wdt_set_heartbeat(new_timeout)) |
325 | return -EINVAL; |
326 | |
327 | wdt_keepalive(); |
328 | /* Fall through */ |
329 | } |
330 | case WDIOC_GETTIMEOUT: |
331 | return put_user(timeout, p); |
332 | default: |
333 | return -ENOTTY; |
334 | } |
335 | } |
336 | |
337 | static const struct file_operations wdt_fops = { |
338 | .owner = THIS_MODULE, |
339 | .llseek = no_llseek, |
340 | .write = fop_write, |
341 | .open = fop_open, |
342 | .release = fop_close, |
343 | .unlocked_ioctl = fop_ioctl, |
344 | }; |
345 | |
346 | static struct miscdevice wdt_miscdev = { |
347 | .minor = WATCHDOG_MINOR, |
348 | .name = "watchdog", |
349 | .fops = &wdt_fops, |
350 | }; |
351 | |
352 | /* |
353 | * Notifier for system down |
354 | */ |
355 | |
356 | static int wdt_notify_sys(struct notifier_block *this, unsigned long code, |
357 | void *unused) |
358 | { |
359 | if (code == SYS_DOWN || code == SYS_HALT) |
360 | wdt_turnoff(); |
361 | return NOTIFY_DONE; |
362 | } |
363 | |
364 | /* |
365 | * The WDT needs to learn about soft shutdowns in order to |
366 | * turn the timebomb registers off. |
367 | */ |
368 | |
369 | static struct notifier_block wdt_notifier = { |
370 | .notifier_call = wdt_notify_sys, |
371 | }; |
372 | |
373 | static void __exit sc520_wdt_unload(void) |
374 | { |
375 | if (!nowayout) |
376 | wdt_turnoff(); |
377 | |
378 | /* Deregister */ |
379 | misc_deregister(&wdt_miscdev); |
380 | unregister_reboot_notifier(&wdt_notifier); |
381 | iounmap(wdtmrctl); |
382 | } |
383 | |
384 | static int __init sc520_wdt_init(void) |
385 | { |
386 | int rc = -EBUSY; |
387 | |
388 | /* Check that the timeout value is within it's range ; |
389 | if not reset to the default */ |
390 | if (wdt_set_heartbeat(timeout)) { |
391 | wdt_set_heartbeat(WATCHDOG_TIMEOUT); |
392 | pr_info("timeout value must be 1 <= timeout <= 3600, using %d\n", |
393 | WATCHDOG_TIMEOUT); |
394 | } |
395 | |
396 | wdtmrctl = ioremap(MMCR_BASE + OFFS_WDTMRCTL, 2); |
397 | if (!wdtmrctl) { |
398 | pr_err("Unable to remap memory\n"); |
399 | rc = -ENOMEM; |
400 | goto err_out_region2; |
401 | } |
402 | |
403 | rc = register_reboot_notifier(&wdt_notifier); |
404 | if (rc) { |
405 | pr_err("cannot register reboot notifier (err=%d)\n", rc); |
406 | goto err_out_ioremap; |
407 | } |
408 | |
409 | rc = misc_register(&wdt_miscdev); |
410 | if (rc) { |
411 | pr_err("cannot register miscdev on minor=%d (err=%d)\n", |
412 | WATCHDOG_MINOR, rc); |
413 | goto err_out_notifier; |
414 | } |
415 | |
416 | pr_info("WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n", |
417 | timeout, nowayout); |
418 | |
419 | return 0; |
420 | |
421 | err_out_notifier: |
422 | unregister_reboot_notifier(&wdt_notifier); |
423 | err_out_ioremap: |
424 | iounmap(wdtmrctl); |
425 | err_out_region2: |
426 | return rc; |
427 | } |
428 | |
429 | module_init(sc520_wdt_init); |
430 | module_exit(sc520_wdt_unload); |
431 | |
432 | MODULE_AUTHOR("Scott and Bill Jennings"); |
433 | MODULE_DESCRIPTION( |
434 | "Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor"); |
435 | MODULE_LICENSE("GPL"); |
436 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |
437 |
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