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 
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 
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 
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 
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 
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 
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 
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 
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 
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 	.llseek		=	no_llseek,
293 	.write		=	fop_write,
294 	.open		=	fop_open,
295 	.release	=	fop_close,
296 	.unlocked_ioctl	=	fop_ioctl,
297 	.compat_ioctl	= 	compat_ptr_ioctl,
298 };
299 
300 static struct miscdevice wdt_miscdev = {
301 	.minor	=	WATCHDOG_MINOR,
302 	.name	=	"watchdog",
303 	.fops	=	&wdt_fops,
304 };
305 
306 static int wdt_restart_handle(struct notifier_block *this, unsigned long mode,
307 			      void *cmd)
308 {
309 	/*
310 	 * Cobalt devices have no way of rebooting themselves other
311 	 * than getting the watchdog to pull reset, so we restart the
312 	 * watchdog on reboot with no heartbeat.
313 	 */
314 	wdt_change(WDT_ENABLE);
315 
316 	/* loop until the watchdog fires */
317 	while (true)
318 		;
319 
320 	return NOTIFY_DONE;
321 }
322 
323 static struct notifier_block wdt_restart_handler = {
324 	.notifier_call = wdt_restart_handle,
325 	.priority = 128,
326 };
327 
328 /*
329  *	Notifier for system down
330  */
331 
332 static int wdt_notify_sys(struct notifier_block *this,
333 					unsigned long code, void *unused)
334 {
335 	if (code == SYS_DOWN || code == SYS_HALT)
336 		wdt_turnoff();
337 
338 	return NOTIFY_DONE;
339 }
340 
341 /*
342  *	The WDT needs to learn about soft shutdowns in order to
343  *	turn the timebomb registers off.
344  */
345 
346 static struct notifier_block wdt_notifier = {
347 	.notifier_call = wdt_notify_sys,
348 };
349 
350 static void __exit alim7101_wdt_unload(void)
351 {
352 	wdt_turnoff();
353 	/* Deregister */
354 	misc_deregister(&wdt_miscdev);
355 	unregister_reboot_notifier(&wdt_notifier);
356 	unregister_restart_handler(&wdt_restart_handler);
357 	pci_dev_put(alim7101_pmu);
358 }
359 
360 static int __init alim7101_wdt_init(void)
361 {
362 	int rc = -EBUSY;
363 	struct pci_dev *ali1543_south;
364 	char tmp;
365 
366 	pr_info("Steve Hill <steve@navaho.co.uk>\n");
367 	alim7101_pmu = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101,
368 		NULL);
369 	if (!alim7101_pmu) {
370 		pr_info("ALi M7101 PMU not present - WDT not set\n");
371 		return -EBUSY;
372 	}
373 
374 	/* Set the WDT in the PMU to 1 second */
375 	pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, 0x02);
376 
377 	ali1543_south = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533,
378 		NULL);
379 	if (!ali1543_south) {
380 		pr_info("ALi 1543 South-Bridge not present - WDT not set\n");
381 		goto err_out;
382 	}
383 	pci_read_config_byte(ali1543_south, 0x5e, &tmp);
384 	pci_dev_put(ali1543_south);
385 	if ((tmp & 0x1e) == 0x00) {
386 		if (!use_gpio) {
387 			pr_info("Detected old alim7101 revision 'a1d'.  If this is a cobalt board, set the 'use_gpio' module parameter.\n");
388 			goto err_out;
389 		}
390 		nowayout = 1;
391 	} else if ((tmp & 0x1e) != 0x12 && (tmp & 0x1e) != 0x00) {
392 		pr_info("ALi 1543 South-Bridge does not have the correct revision number (???1001?) - WDT not set\n");
393 		goto err_out;
394 	}
395 
396 	if (timeout < 1 || timeout > 3600) {
397 		/* arbitrary upper limit */
398 		timeout = WATCHDOG_TIMEOUT;
399 		pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
400 			timeout);
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;
407 	}
408 
409 	rc = register_restart_handler(&wdt_restart_handler);
410 	if (rc) {
411 		pr_err("cannot register restart handler (err=%d)\n", rc);
412 		goto err_out_reboot;
413 	}
414 
415 	rc = misc_register(&wdt_miscdev);
416 	if (rc) {
417 		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
418 		       wdt_miscdev.minor, rc);
419 		goto err_out_restart;
420 	}
421 
422 	if (nowayout)
423 		__module_get(THIS_MODULE);
424 
425 	pr_info("WDT driver for ALi M7101 initialised. timeout=%d sec (nowayout=%d)\n",
426 		timeout, nowayout);
427 	return 0;
428 
429 err_out_restart:
430 	unregister_restart_handler(&wdt_restart_handler);
431 err_out_reboot:
432 	unregister_reboot_notifier(&wdt_notifier);
433 err_out:
434 	pci_dev_put(alim7101_pmu);
435 	return rc;
436 }
437 
438 module_init(alim7101_wdt_init);
439 module_exit(alim7101_wdt_unload);
440 
441 static const struct pci_device_id alim7101_pci_tbl[] __used = {
442 	{ PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533) },
443 	{ PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101) },
444 	{ }
445 };
446 
447 MODULE_DEVICE_TABLE(pci, alim7101_pci_tbl);
448 
449 MODULE_AUTHOR("Steve Hill");
450 MODULE_DESCRIPTION("ALi M7101 PMU Computer Watchdog Timer driver");
451 MODULE_LICENSE("GPL");
452