Commit | Line | Data |
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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
1da177e4 LT |
2 | /* |
3 | * AMD Elan SC520 processor Watchdog Timer driver | |
4 | * | |
143a2e54 WVS |
5 | * Based on acquirewdt.c by Alan Cox, |
6 | * and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net> | |
1da177e4 | 7 | * |
1da177e4 LT |
8 | * The authors do NOT admit liability nor provide warranty for |
9 | * any of this software. This material is provided "AS-IS" in | |
143a2e54 | 10 | * the hope that it may be useful for others. |
1da177e4 LT |
11 | * |
12 | * (c) Copyright 2001 Scott Jennings <linuxdrivers@oro.net> | |
13 | * 9/27 - 2001 [Initial release] | |
14 | * | |
15 | * Additional fixes Alan Cox | |
16 | * - Fixed formatting | |
17 | * - Removed debug printks | |
18 | * - Fixed SMP built kernel deadlock | |
19 | * - Switched to private locks not lock_kernel | |
20 | * - Used ioremap/writew/readw | |
21 | * - Added NOWAYOUT support | |
22 | * 4/12 - 2002 Changes by Rob Radez <rob@osinvestor.com> | |
23 | * - Change comments | |
24 | * - Eliminate fop_llseek | |
25 | * - Change CONFIG_WATCHDOG_NOWAYOUT semantics | |
26 | * - Add KERN_* tags to printks | |
27 | * - fix possible wdt_is_open race | |
28 | * - Report proper capabilities in watchdog_info | |
29 | * - Add WDIOC_{GETSTATUS, GETBOOTSTATUS, SETTIMEOUT, | |
30 | * GETTIMEOUT, SETOPTIONS} ioctls | |
31 | * 09/8 - 2003 Changes by Wim Van Sebroeck <wim@iguana.be> | |
32 | * - cleanup of trailing spaces | |
33 | * - added extra printk's for startup problems | |
34 | * - use module_param | |
35 | * - made timeout (the emulated heartbeat) a module_param | |
36 | * - made the keepalive ping an internal subroutine | |
37 | * 3/27 - 2004 Changes by Sean Young <sean@mess.org> | |
38 | * - set MMCR_BASE to 0xfffef000 | |
39 | * - CBAR does not need to be read | |
40 | * - removed debugging printks | |
41 | * | |
42 | * This WDT driver is different from most other Linux WDT | |
43 | * drivers in that the driver will ping the watchdog by itself, | |
44 | * because this particular WDT has a very short timeout (1.6 | |
45 | * seconds) and it would be insane to count on any userspace | |
46 | * daemon always getting scheduled within that time frame. | |
47 | * | |
48 | * This driver uses memory mapped IO, and spinlock. | |
49 | */ | |
50 | ||
27c766aa JP |
51 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
52 | ||
1da177e4 LT |
53 | #include <linux/module.h> |
54 | #include <linux/moduleparam.h> | |
55 | #include <linux/types.h> | |
56 | #include <linux/timer.h> | |
57 | #include <linux/miscdevice.h> | |
58 | #include <linux/watchdog.h> | |
59 | #include <linux/fs.h> | |
60 | #include <linux/ioport.h> | |
61 | #include <linux/notifier.h> | |
62 | #include <linux/reboot.h> | |
63 | #include <linux/init.h> | |
4e57b681 | 64 | #include <linux/jiffies.h> |
ff948060 AC |
65 | #include <linux/io.h> |
66 | #include <linux/uaccess.h> | |
1da177e4 | 67 | |
1da177e4 | 68 | |
1da177e4 LT |
69 | /* |
70 | * The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7) | |
71 | * | |
72 | * 0: 492us 2: 1.01s 4: 4.03s 6: 16.22s | |
73 | * 1: 503ms 3: 2.01s 5: 8.05s 7: 32.21s | |
74 | * | |
75 | * We will program the SC520 watchdog for a timeout of 2.01s. | |
76 | * If we reset the watchdog every ~250ms we should be safe. | |
77 | */ | |
78 | ||
79 | #define WDT_INTERVAL (HZ/4+1) | |
80 | ||
81 | /* | |
82 | * We must not require too good response from the userspace daemon. | |
83 | * Here we require the userspace daemon to send us a heartbeat | |
84 | * char to /dev/watchdog every 30 seconds. | |
85 | */ | |
86 | ||
87 | #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */ | |
ff948060 AC |
88 | /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */ |
89 | static int timeout = WATCHDOG_TIMEOUT; | |
1da177e4 | 90 | module_param(timeout, int, 0); |
ff948060 AC |
91 | MODULE_PARM_DESC(timeout, |
92 | "Watchdog timeout in seconds. (1 <= timeout <= 3600, default=" | |
93 | __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); | |
1da177e4 | 94 | |
86a1e189 WVS |
95 | static bool nowayout = WATCHDOG_NOWAYOUT; |
96 | module_param(nowayout, bool, 0); | |
ff948060 AC |
97 | MODULE_PARM_DESC(nowayout, |
98 | "Watchdog cannot be stopped once started (default=" | |
99 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); | |
1da177e4 LT |
100 | |
101 | /* | |
102 | * AMD Elan SC520 - Watchdog Timer Registers | |
103 | */ | |
104 | #define MMCR_BASE 0xfffef000 /* The default base address */ | |
105 | #define OFFS_WDTMRCTL 0xCB0 /* Watchdog Timer Control Register */ | |
106 | ||
107 | /* WDT Control Register bit definitions */ | |
108 | #define WDT_EXP_SEL_01 0x0001 /* [01] Time-out = 496 us (with 33 Mhz clk). */ | |
109 | #define WDT_EXP_SEL_02 0x0002 /* [02] Time-out = 508 ms (with 33 Mhz clk). */ | |
110 | #define WDT_EXP_SEL_03 0x0004 /* [03] Time-out = 1.02 s (with 33 Mhz clk). */ | |
111 | #define WDT_EXP_SEL_04 0x0008 /* [04] Time-out = 2.03 s (with 33 Mhz clk). */ | |
112 | #define WDT_EXP_SEL_05 0x0010 /* [05] Time-out = 4.07 s (with 33 Mhz clk). */ | |
113 | #define WDT_EXP_SEL_06 0x0020 /* [06] Time-out = 8.13 s (with 33 Mhz clk). */ | |
114 | #define WDT_EXP_SEL_07 0x0040 /* [07] Time-out = 16.27s (with 33 Mhz clk). */ | |
115 | #define WDT_EXP_SEL_08 0x0080 /* [08] Time-out = 32.54s (with 33 Mhz clk). */ | |
116 | #define WDT_IRQ_FLG 0x1000 /* [12] Interrupt Request Flag */ | |
117 | #define WDT_WRST_ENB 0x4000 /* [14] Watchdog Timer Reset Enable */ | |
118 | #define WDT_ENB 0x8000 /* [15] Watchdog Timer Enable */ | |
119 | ||
120 | static __u16 __iomem *wdtmrctl; | |
121 | ||
24ed960a | 122 | static void wdt_timer_ping(struct timer_list *); |
1d27e3e2 | 123 | static DEFINE_TIMER(timer, wdt_timer_ping); |
1da177e4 LT |
124 | static unsigned long next_heartbeat; |
125 | static unsigned long wdt_is_open; | |
126 | static char wdt_expect_close; | |
c7dfd0cc | 127 | static DEFINE_SPINLOCK(wdt_spinlock); |
1da177e4 LT |
128 | |
129 | /* | |
130 | * Whack the dog | |
131 | */ | |
132 | ||
24ed960a | 133 | static void wdt_timer_ping(struct timer_list *unused) |
1da177e4 LT |
134 | { |
135 | /* If we got a heartbeat pulse within the WDT_US_INTERVAL | |
136 | * we agree to ping the WDT | |
137 | */ | |
ff948060 | 138 | if (time_before(jiffies, next_heartbeat)) { |
1da177e4 LT |
139 | /* Ping the WDT */ |
140 | spin_lock(&wdt_spinlock); | |
141 | writew(0xAAAA, wdtmrctl); | |
142 | writew(0x5555, wdtmrctl); | |
143 | spin_unlock(&wdt_spinlock); | |
144 | ||
145 | /* Re-set the timer interval */ | |
82eb7c50 | 146 | mod_timer(&timer, jiffies + WDT_INTERVAL); |
ff948060 | 147 | } else |
27c766aa | 148 | pr_warn("Heartbeat lost! Will not ping the watchdog\n"); |
1da177e4 LT |
149 | } |
150 | ||
151 | /* | |
152 | * Utility routines | |
153 | */ | |
154 | ||
155 | static void wdt_config(int writeval) | |
156 | { | |
1da177e4 LT |
157 | unsigned long flags; |
158 | ||
159 | /* buy some time (ping) */ | |
160 | spin_lock_irqsave(&wdt_spinlock, flags); | |
a9ba8376 | 161 | readw(wdtmrctl); /* ensure write synchronization */ |
1da177e4 LT |
162 | writew(0xAAAA, wdtmrctl); |
163 | writew(0x5555, wdtmrctl); | |
164 | /* unlock WDT = make WDT configuration register writable one time */ | |
165 | writew(0x3333, wdtmrctl); | |
166 | writew(0xCCCC, wdtmrctl); | |
167 | /* write WDT configuration register */ | |
168 | writew(writeval, wdtmrctl); | |
169 | spin_unlock_irqrestore(&wdt_spinlock, flags); | |
170 | } | |
171 | ||
172 | static int wdt_startup(void) | |
173 | { | |
174 | next_heartbeat = jiffies + (timeout * HZ); | |
175 | ||
176 | /* Start the timer */ | |
82eb7c50 | 177 | mod_timer(&timer, jiffies + WDT_INTERVAL); |
1da177e4 LT |
178 | |
179 | /* Start the watchdog */ | |
180 | wdt_config(WDT_ENB | WDT_WRST_ENB | WDT_EXP_SEL_04); | |
181 | ||
27c766aa | 182 | pr_info("Watchdog timer is now enabled\n"); |
1da177e4 LT |
183 | return 0; |
184 | } | |
185 | ||
186 | static int wdt_turnoff(void) | |
187 | { | |
188 | /* Stop the timer */ | |
189 | del_timer(&timer); | |
190 | ||
191 | /* Stop the watchdog */ | |
192 | wdt_config(0); | |
193 | ||
27c766aa | 194 | pr_info("Watchdog timer is now disabled...\n"); |
1da177e4 LT |
195 | return 0; |
196 | } | |
197 | ||
198 | static int wdt_keepalive(void) | |
199 | { | |
200 | /* user land ping */ | |
201 | next_heartbeat = jiffies + (timeout * HZ); | |
202 | return 0; | |
203 | } | |
204 | ||
205 | static int wdt_set_heartbeat(int t) | |
206 | { | |
207 | if ((t < 1) || (t > 3600)) /* arbitrary upper limit */ | |
208 | return -EINVAL; | |
209 | ||
210 | timeout = t; | |
211 | return 0; | |
212 | } | |
213 | ||
214 | /* | |
215 | * /dev/watchdog handling | |
216 | */ | |
217 | ||
ff948060 AC |
218 | static ssize_t fop_write(struct file *file, const char __user *buf, |
219 | size_t count, loff_t *ppos) | |
1da177e4 LT |
220 | { |
221 | /* See if we got the magic character 'V' and reload the timer */ | |
ff948060 | 222 | if (count) { |
1da177e4 LT |
223 | if (!nowayout) { |
224 | size_t ofs; | |
225 | ||
226 | /* note: just in case someone wrote the magic character | |
227 | * five months ago... */ | |
228 | wdt_expect_close = 0; | |
229 | ||
230 | /* now scan */ | |
ff948060 | 231 | for (ofs = 0; ofs != count; ofs++) { |
1da177e4 LT |
232 | char c; |
233 | if (get_user(c, buf + ofs)) | |
234 | return -EFAULT; | |
ff948060 | 235 | if (c == 'V') |
1da177e4 LT |
236 | wdt_expect_close = 42; |
237 | } | |
238 | } | |
239 | ||
ff948060 AC |
240 | /* Well, anyhow someone wrote to us, we should |
241 | return that favour */ | |
1da177e4 LT |
242 | wdt_keepalive(); |
243 | } | |
244 | return count; | |
245 | } | |
246 | ||
ff948060 | 247 | static int fop_open(struct inode *inode, struct file *file) |
1da177e4 | 248 | { |
1da177e4 | 249 | /* Just in case we're already talking to someone... */ |
ff948060 | 250 | if (test_and_set_bit(0, &wdt_is_open)) |
1da177e4 LT |
251 | return -EBUSY; |
252 | if (nowayout) | |
253 | __module_get(THIS_MODULE); | |
254 | ||
255 | /* Good, fire up the show */ | |
256 | wdt_startup(); | |
c5bf68fe | 257 | return stream_open(inode, file); |
1da177e4 LT |
258 | } |
259 | ||
ff948060 | 260 | static int fop_close(struct inode *inode, struct file *file) |
1da177e4 | 261 | { |
ff948060 | 262 | if (wdt_expect_close == 42) |
1da177e4 | 263 | wdt_turnoff(); |
ff948060 | 264 | else { |
27c766aa | 265 | pr_crit("Unexpected close, not stopping watchdog!\n"); |
1da177e4 LT |
266 | wdt_keepalive(); |
267 | } | |
268 | clear_bit(0, &wdt_is_open); | |
269 | wdt_expect_close = 0; | |
270 | return 0; | |
271 | } | |
272 | ||
9b748ed0 | 273 | static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg) |
1da177e4 LT |
274 | { |
275 | void __user *argp = (void __user *)arg; | |
276 | int __user *p = argp; | |
ff948060 AC |
277 | static const struct watchdog_info ident = { |
278 | .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | |
279 | | WDIOF_MAGICCLOSE, | |
1da177e4 LT |
280 | .firmware_version = 1, |
281 | .identity = "SC520", | |
282 | }; | |
283 | ||
5eb82498 | 284 | switch (cmd) { |
ff948060 AC |
285 | case WDIOC_GETSUPPORT: |
286 | return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; | |
287 | case WDIOC_GETSTATUS: | |
288 | case WDIOC_GETBOOTSTATUS: | |
289 | return put_user(0, p); | |
ff948060 AC |
290 | case WDIOC_SETOPTIONS: |
291 | { | |
292 | int new_options, retval = -EINVAL; | |
1da177e4 | 293 | |
ff948060 AC |
294 | if (get_user(new_options, p)) |
295 | return -EFAULT; | |
296 | ||
297 | if (new_options & WDIOS_DISABLECARD) { | |
298 | wdt_turnoff(); | |
299 | retval = 0; | |
300 | } | |
1da177e4 | 301 | |
ff948060 AC |
302 | if (new_options & WDIOS_ENABLECARD) { |
303 | wdt_startup(); | |
304 | retval = 0; | |
1da177e4 | 305 | } |
1da177e4 | 306 | |
ff948060 AC |
307 | return retval; |
308 | } | |
0c06090c WVS |
309 | case WDIOC_KEEPALIVE: |
310 | wdt_keepalive(); | |
311 | return 0; | |
ff948060 AC |
312 | case WDIOC_SETTIMEOUT: |
313 | { | |
314 | int new_timeout; | |
1da177e4 | 315 | |
ff948060 AC |
316 | if (get_user(new_timeout, p)) |
317 | return -EFAULT; | |
1da177e4 | 318 | |
ff948060 AC |
319 | if (wdt_set_heartbeat(new_timeout)) |
320 | return -EINVAL; | |
321 | ||
322 | wdt_keepalive(); | |
ff948060 | 323 | } |
e70d3547 | 324 | /* Fall through */ |
ff948060 AC |
325 | case WDIOC_GETTIMEOUT: |
326 | return put_user(timeout, p); | |
0c06090c WVS |
327 | default: |
328 | return -ENOTTY; | |
1da177e4 LT |
329 | } |
330 | } | |
331 | ||
62322d25 | 332 | static const struct file_operations wdt_fops = { |
1da177e4 LT |
333 | .owner = THIS_MODULE, |
334 | .llseek = no_llseek, | |
335 | .write = fop_write, | |
336 | .open = fop_open, | |
337 | .release = fop_close, | |
9b748ed0 | 338 | .unlocked_ioctl = fop_ioctl, |
1da177e4 LT |
339 | }; |
340 | ||
341 | static struct miscdevice wdt_miscdev = { | |
342 | .minor = WATCHDOG_MINOR, | |
343 | .name = "watchdog", | |
344 | .fops = &wdt_fops, | |
345 | }; | |
346 | ||
347 | /* | |
348 | * Notifier for system down | |
349 | */ | |
350 | ||
351 | static int wdt_notify_sys(struct notifier_block *this, unsigned long code, | |
352 | void *unused) | |
353 | { | |
ff948060 | 354 | if (code == SYS_DOWN || code == SYS_HALT) |
1da177e4 LT |
355 | wdt_turnoff(); |
356 | return NOTIFY_DONE; | |
357 | } | |
358 | ||
359 | /* | |
360 | * The WDT needs to learn about soft shutdowns in order to | |
361 | * turn the timebomb registers off. | |
362 | */ | |
363 | ||
364 | static struct notifier_block wdt_notifier = { | |
365 | .notifier_call = wdt_notify_sys, | |
366 | }; | |
367 | ||
368 | static void __exit sc520_wdt_unload(void) | |
369 | { | |
370 | if (!nowayout) | |
371 | wdt_turnoff(); | |
372 | ||
373 | /* Deregister */ | |
374 | misc_deregister(&wdt_miscdev); | |
375 | unregister_reboot_notifier(&wdt_notifier); | |
376 | iounmap(wdtmrctl); | |
377 | } | |
378 | ||
379 | static int __init sc520_wdt_init(void) | |
380 | { | |
381 | int rc = -EBUSY; | |
382 | ||
ff948060 AC |
383 | /* Check that the timeout value is within it's range ; |
384 | if not reset to the default */ | |
1da177e4 LT |
385 | if (wdt_set_heartbeat(timeout)) { |
386 | wdt_set_heartbeat(WATCHDOG_TIMEOUT); | |
27c766aa JP |
387 | pr_info("timeout value must be 1 <= timeout <= 3600, using %d\n", |
388 | WATCHDOG_TIMEOUT); | |
1da177e4 LT |
389 | } |
390 | ||
cef153a8 | 391 | wdtmrctl = ioremap(MMCR_BASE + OFFS_WDTMRCTL, 2); |
1da177e4 | 392 | if (!wdtmrctl) { |
27c766aa | 393 | pr_err("Unable to remap memory\n"); |
1da177e4 LT |
394 | rc = -ENOMEM; |
395 | goto err_out_region2; | |
396 | } | |
397 | ||
398 | rc = register_reboot_notifier(&wdt_notifier); | |
399 | if (rc) { | |
27c766aa | 400 | pr_err("cannot register reboot notifier (err=%d)\n", rc); |
1da177e4 LT |
401 | goto err_out_ioremap; |
402 | } | |
403 | ||
404 | rc = misc_register(&wdt_miscdev); | |
405 | if (rc) { | |
27c766aa JP |
406 | pr_err("cannot register miscdev on minor=%d (err=%d)\n", |
407 | WATCHDOG_MINOR, rc); | |
1da177e4 LT |
408 | goto err_out_notifier; |
409 | } | |
410 | ||
27c766aa JP |
411 | pr_info("WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n", |
412 | timeout, nowayout); | |
1da177e4 LT |
413 | |
414 | return 0; | |
415 | ||
416 | err_out_notifier: | |
417 | unregister_reboot_notifier(&wdt_notifier); | |
418 | err_out_ioremap: | |
419 | iounmap(wdtmrctl); | |
420 | err_out_region2: | |
421 | return rc; | |
422 | } | |
423 | ||
424 | module_init(sc520_wdt_init); | |
425 | module_exit(sc520_wdt_unload); | |
426 | ||
427 | MODULE_AUTHOR("Scott and Bill Jennings"); | |
143a2e54 WVS |
428 | MODULE_DESCRIPTION( |
429 | "Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor"); | |
1da177e4 | 430 | MODULE_LICENSE("GPL"); |