1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * ALi M7101 PMU Computer Watchdog Timer driver
4 *
5 * Based on w83877f_wdt.c by Scott Jennings <linuxdrivers@oro.net>
6 * and the Cobalt kernel WDT timer driver by Tim Hockin
7 * <thockin@cobaltnet.com>
8 *
9 * (c)2002 Steve Hill <steve@navaho.co.uk>
10 *
11 * This WDT driver is different from most other Linux WDT
12 * drivers in that the driver will ping the watchdog by itself,
13 * because this particular WDT has a very short timeout (1.6
14 * seconds) and it would be insane to count on any userspace
15 * daemon always getting scheduled within that time frame.
16 *
17 * Additions:
18 * Aug 23, 2004 - Added use_gpio module parameter for use on revision a1d PMUs
19 * found on very old cobalt hardware.
20 * -- Mike Waychison <michael.waychison@sun.com>
21 */
22
23 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
24
25 #include <linux/module.h>
26 #include <linux/moduleparam.h>
27 #include <linux/types.h>
28 #include <linux/timer.h>
29 #include <linux/miscdevice.h>
30 #include <linux/watchdog.h>
31 #include <linux/ioport.h>
32 #include <linux/notifier.h>
33 #include <linux/reboot.h>
34 #include <linux/init.h>
35 #include <linux/fs.h>
36 #include <linux/pci.h>
37 #include <linux/io.h>
38 #include <linux/uaccess.h>
39
40
41 #define WDT_ENABLE 0x9C
42 #define WDT_DISABLE 0x8C
43
44 #define ALI_7101_WDT 0x92
45 #define ALI_7101_GPIO 0x7D
46 #define ALI_7101_GPIO_O 0x7E
47 #define ALI_WDT_ARM 0x01
48
49 /*
50 * We're going to use a 1 second timeout.
51 * If we reset the watchdog every ~250ms we should be safe. */
52
53 #define WDT_INTERVAL (HZ/4+1)
54
55 /*
56 * We must not require too good response from the userspace daemon.
57 * Here we require the userspace daemon to send us a heartbeat
58 * char to /dev/watchdog every 30 seconds.
59 */
60
61 #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
62 /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
63 static int timeout = WATCHDOG_TIMEOUT;
64 module_param(timeout, int, 0);
65 MODULE_PARM_DESC(timeout,
66 "Watchdog timeout in seconds. (1<=timeout<=3600, default="
67 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
68
69 static int use_gpio; /* Use the pic (for a1d revision alim7101) */
70 module_param(use_gpio, int, 0);
71 MODULE_PARM_DESC(use_gpio,
72 "Use the gpio watchdog (required by old cobalt boards).");
73
74 static void wdt_timer_ping(struct timer_list *);
75 static DEFINE_TIMER(timer, wdt_timer_ping);
76 static unsigned long next_heartbeat;
77 static unsigned long wdt_is_open;
78 static char wdt_expect_close;
79 static struct pci_dev *alim7101_pmu;
80
81 static bool nowayout = WATCHDOG_NOWAYOUT;
82 module_param(nowayout, bool, 0);
83 MODULE_PARM_DESC(nowayout,
84 "Watchdog cannot be stopped once started (default="
85 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
86
87 /*
88 * Whack the dog
89 */
90
wdt_timer_ping(struct timer_list * unused)91 static void wdt_timer_ping(struct timer_list *unused)
92 {
93 /* If we got a heartbeat pulse within the WDT_US_INTERVAL
94 * we agree to ping the WDT
95 */
96 char tmp;
97
98 if (time_before(jiffies, next_heartbeat)) {
99 /* Ping the WDT (this is actually a disarm/arm sequence) */
100 pci_read_config_byte(alim7101_pmu, 0x92, &tmp);
101 pci_write_config_byte(alim7101_pmu,
102 ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
103 pci_write_config_byte(alim7101_pmu,
104 ALI_7101_WDT, (tmp | ALI_WDT_ARM));
105 if (use_gpio) {
106 pci_read_config_byte(alim7101_pmu,
107 ALI_7101_GPIO_O, &tmp);
108 pci_write_config_byte(alim7101_pmu,
109 ALI_7101_GPIO_O, tmp | 0x20);
110 pci_write_config_byte(alim7101_pmu,
111 ALI_7101_GPIO_O, tmp & ~0x20);
112 }
113 } else {
114 pr_warn("Heartbeat lost! Will not ping the watchdog\n");
115 }
116 /* Re-set the timer interval */
117 mod_timer(&timer, jiffies + WDT_INTERVAL);
118 }
119
120 /*
121 * Utility routines
122 */
123
wdt_change(int writeval)124 static void wdt_change(int writeval)
125 {
126 char tmp;
127
128 pci_read_config_byte(alim7101_pmu, ALI_7101_WDT, &tmp);
129 if (writeval == WDT_ENABLE) {
130 pci_write_config_byte(alim7101_pmu,
131 ALI_7101_WDT, (tmp | ALI_WDT_ARM));
132 if (use_gpio) {
133 pci_read_config_byte(alim7101_pmu,
134 ALI_7101_GPIO_O, &tmp);
135 pci_write_config_byte(alim7101_pmu,
136 ALI_7101_GPIO_O, tmp & ~0x20);
137 }
138
139 } else {
140 pci_write_config_byte(alim7101_pmu,
141 ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
142 if (use_gpio) {
143 pci_read_config_byte(alim7101_pmu,
144 ALI_7101_GPIO_O, &tmp);
145 pci_write_config_byte(alim7101_pmu,
146 ALI_7101_GPIO_O, tmp | 0x20);
147 }
148 }
149 }
150
wdt_startup(void)151 static void wdt_startup(void)
152 {
153 next_heartbeat = jiffies + (timeout * HZ);
154
155 /* We must enable before we kick off the timer in case the timer
156 occurs as we ping it */
157
158 wdt_change(WDT_ENABLE);
159
160 /* Start the timer */
161 mod_timer(&timer, jiffies + WDT_INTERVAL);
162
163 pr_info("Watchdog timer is now enabled\n");
164 }
165
wdt_turnoff(void)166 static void wdt_turnoff(void)
167 {
168 /* Stop the timer */
169 del_timer_sync(&timer);
170 wdt_change(WDT_DISABLE);
171 pr_info("Watchdog timer is now disabled...\n");
172 }
173
wdt_keepalive(void)174 static void wdt_keepalive(void)
175 {
176 /* user land ping */
177 next_heartbeat = jiffies + (timeout * HZ);
178 }
179
180 /*
181 * /dev/watchdog handling
182 */
183
fop_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)184 static ssize_t fop_write(struct file *file, const char __user *buf,
185 size_t count, loff_t *ppos)
186 {
187 /* See if we got the magic character 'V' and reload the timer */
188 if (count) {
189 if (!nowayout) {
190 size_t ofs;
191
192 /* note: just in case someone wrote the magic character
193 * five months ago... */
194 wdt_expect_close = 0;
195
196 /* now scan */
197 for (ofs = 0; ofs != count; ofs++) {
198 char c;
199 if (get_user(c, buf + ofs))
200 return -EFAULT;
201 if (c == 'V')
202 wdt_expect_close = 42;
203 }
204 }
205 /* someone wrote to us, we should restart timer */
206 wdt_keepalive();
207 }
208 return count;
209 }
210
fop_open(struct inode * inode,struct file * file)211 static int fop_open(struct inode *inode, struct file *file)
212 {
213 /* Just in case we're already talking to someone... */
214 if (test_and_set_bit(0, &wdt_is_open))
215 return -EBUSY;
216 /* Good, fire up the show */
217 wdt_startup();
218 return stream_open(inode, file);
219 }
220
fop_close(struct inode * inode,struct file * file)221 static int fop_close(struct inode *inode, struct file *file)
222 {
223 if (wdt_expect_close == 42)
224 wdt_turnoff();
225 else {
226 /* wim: shouldn't there be a: del_timer(&timer); */
227 pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
228 }
229 clear_bit(0, &wdt_is_open);
230 wdt_expect_close = 0;
231 return 0;
232 }
233
fop_ioctl(struct file * file,unsigned int cmd,unsigned long arg)234 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
235 {
236 void __user *argp = (void __user *)arg;
237 int __user *p = argp;
238 static const struct watchdog_info ident = {
239 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
240 | WDIOF_MAGICCLOSE,
241 .firmware_version = 1,
242 .identity = "ALiM7101",
243 };
244
245 switch (cmd) {
246 case WDIOC_GETSUPPORT:
247 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
248 case WDIOC_GETSTATUS:
249 case WDIOC_GETBOOTSTATUS:
250 return put_user(0, p);
251 case WDIOC_SETOPTIONS:
252 {
253 int new_options, retval = -EINVAL;
254
255 if (get_user(new_options, p))
256 return -EFAULT;
257 if (new_options & WDIOS_DISABLECARD) {
258 wdt_turnoff();
259 retval = 0;
260 }
261 if (new_options & WDIOS_ENABLECARD) {
262 wdt_startup();
263 retval = 0;
264 }
265 return retval;
266 }
267 case WDIOC_KEEPALIVE:
268 wdt_keepalive();
269 return 0;
270 case WDIOC_SETTIMEOUT:
271 {
272 int new_timeout;
273
274 if (get_user(new_timeout, p))
275 return -EFAULT;
276 /* arbitrary upper limit */
277 if (new_timeout < 1 || new_timeout > 3600)
278 return -EINVAL;
279 timeout = new_timeout;
280 wdt_keepalive();
281 }
282 fallthrough;
283 case WDIOC_GETTIMEOUT:
284 return put_user(timeout, p);
285 default:
286 return -ENOTTY;
287 }
288 }
289
290 static const struct file_operations wdt_fops = {
291 .owner = THIS_MODULE,
292 .write = fop_write,
293 .open = fop_open,
294 .release = fop_close,
295 .unlocked_ioctl = fop_ioctl,
296 .compat_ioctl = compat_ptr_ioctl,
297 };
298
299 static struct miscdevice wdt_miscdev = {
300 .minor = WATCHDOG_MINOR,
301 .name = "watchdog",
302 .fops = &wdt_fops,
303 };
304
wdt_restart_handle(struct notifier_block * this,unsigned long mode,void * cmd)305 static int wdt_restart_handle(struct notifier_block *this, unsigned long mode,
306 void *cmd)
307 {
308 /*
309 * Cobalt devices have no way of rebooting themselves other
310 * than getting the watchdog to pull reset, so we restart the
311 * watchdog on reboot with no heartbeat.
312 */
313 wdt_change(WDT_ENABLE);
314
315 /* loop until the watchdog fires */
316 while (true)
317 ;
318
319 return NOTIFY_DONE;
320 }
321
322 static struct notifier_block wdt_restart_handler = {
323 .notifier_call = wdt_restart_handle,
324 .priority = 128,
325 };
326
327 /*
328 * Notifier for system down
329 */
330
wdt_notify_sys(struct notifier_block * this,unsigned long code,void * unused)331 static int wdt_notify_sys(struct notifier_block *this,
332 unsigned long code, void *unused)
333 {
334 if (code == SYS_DOWN || code == SYS_HALT)
335 wdt_turnoff();
336
337 return NOTIFY_DONE;
338 }
339
340 /*
341 * The WDT needs to learn about soft shutdowns in order to
342 * turn the timebomb registers off.
343 */
344
345 static struct notifier_block wdt_notifier = {
346 .notifier_call = wdt_notify_sys,
347 };
348
alim7101_wdt_unload(void)349 static void __exit alim7101_wdt_unload(void)
350 {
351 wdt_turnoff();
352 /* Deregister */
353 misc_deregister(&wdt_miscdev);
354 unregister_reboot_notifier(&wdt_notifier);
355 unregister_restart_handler(&wdt_restart_handler);
356 pci_dev_put(alim7101_pmu);
357 }
358
alim7101_wdt_init(void)359 static int __init alim7101_wdt_init(void)
360 {
361 int rc = -EBUSY;
362 struct pci_dev *ali1543_south;
363 char tmp;
364
365 pr_info("Steve Hill <steve@navaho.co.uk>\n");
366 alim7101_pmu = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101,
367 NULL);
368 if (!alim7101_pmu) {
369 pr_info("ALi M7101 PMU not present - WDT not set\n");
370 return -EBUSY;
371 }
372
373 /* Set the WDT in the PMU to 1 second */
374 pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, 0x02);
375
376 ali1543_south = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533,
377 NULL);
378 if (!ali1543_south) {
379 pr_info("ALi 1543 South-Bridge not present - WDT not set\n");
380 goto err_out;
381 }
382 pci_read_config_byte(ali1543_south, 0x5e, &tmp);
383 pci_dev_put(ali1543_south);
384 if ((tmp & 0x1e) == 0x00) {
385 if (!use_gpio) {
386 pr_info("Detected old alim7101 revision 'a1d'. If this is a cobalt board, set the 'use_gpio' module parameter.\n");
387 goto err_out;
388 }
389 nowayout = 1;
390 } else if ((tmp & 0x1e) != 0x12 && (tmp & 0x1e) != 0x00) {
391 pr_info("ALi 1543 South-Bridge does not have the correct revision number (???1001?) - WDT not set\n");
392 goto err_out;
393 }
394
395 if (timeout < 1 || timeout > 3600) {
396 /* arbitrary upper limit */
397 timeout = WATCHDOG_TIMEOUT;
398 pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
399 timeout);
400 }
401
402 rc = register_reboot_notifier(&wdt_notifier);
403 if (rc) {
404 pr_err("cannot register reboot notifier (err=%d)\n", rc);
405 goto err_out;
406 }
407
408 rc = register_restart_handler(&wdt_restart_handler);
409 if (rc) {
410 pr_err("cannot register restart handler (err=%d)\n", rc);
411 goto err_out_reboot;
412 }
413
414 rc = misc_register(&wdt_miscdev);
415 if (rc) {
416 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
417 wdt_miscdev.minor, rc);
418 goto err_out_restart;
419 }
420
421 if (nowayout)
422 __module_get(THIS_MODULE);
423
424 pr_info("WDT driver for ALi M7101 initialised. timeout=%d sec (nowayout=%d)\n",
425 timeout, nowayout);
426 return 0;
427
428 err_out_restart:
429 unregister_restart_handler(&wdt_restart_handler);
430 err_out_reboot:
431 unregister_reboot_notifier(&wdt_notifier);
432 err_out:
433 pci_dev_put(alim7101_pmu);
434 return rc;
435 }
436
437 module_init(alim7101_wdt_init);
438 module_exit(alim7101_wdt_unload);
439
440 static const struct pci_device_id alim7101_pci_tbl[] __used = {
441 { PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533) },
442 { PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101) },
443 { }
444 };
445
446 MODULE_DEVICE_TABLE(pci, alim7101_pci_tbl);
447
448 MODULE_AUTHOR("Steve Hill");
449 MODULE_DESCRIPTION("ALi M7101 PMU Computer Watchdog Timer driver");
450 MODULE_LICENSE("GPL");
451