1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *	Eurotech CPU-1220/1410/1420 on board WDT driver
4  *
5  *	(c) Copyright 2001 Ascensit <support@ascensit.com>
6  *	(c) Copyright 2001 Rodolfo Giometti <giometti@ascensit.com>
7  *	(c) Copyright 2002 Rob Radez <rob@osinvestor.com>
8  *
9  *	Based on wdt.c.
10  *	Original copyright messages:
11  *
12  *	(c) Copyright 1996-1997 Alan Cox <alan@lxorguk.ukuu.org.uk>,
13  *						All Rights Reserved.
14  *
15  *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
16  *	warranty for any of this software. This material is provided
17  *	"AS-IS" and at no charge.
18  *
19  *	(c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>*
20  */
21 
22 /* Changelog:
23  *
24  * 2001 - Rodolfo Giometti
25  *	Initial release
26  *
27  * 2002/04/25 - Rob Radez
28  *	clean up #includes
29  *	clean up locking
30  *	make __setup param unique
31  *	proper options in watchdog_info
32  *	add WDIOC_GETSTATUS and WDIOC_SETOPTIONS ioctls
33  *	add expect_close support
34  *
35  * 2002.05.30 - Joel Becker <joel.becker@oracle.com>
36  *	Added Matt Domsch's nowayout module option.
37  */
38 
39 /*
40  *	The eurotech CPU-1220/1410/1420's watchdog is a part
41  *	of the on-board SUPER I/O device SMSC FDC 37B782.
42  */
43 
44 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
45 
46 #include <linux/interrupt.h>
47 #include <linux/module.h>
48 #include <linux/moduleparam.h>
49 #include <linux/types.h>
50 #include <linux/miscdevice.h>
51 #include <linux/watchdog.h>
52 #include <linux/fs.h>
53 #include <linux/ioport.h>
54 #include <linux/notifier.h>
55 #include <linux/reboot.h>
56 #include <linux/init.h>
57 #include <linux/io.h>
58 #include <linux/uaccess.h>
59 
60 
61 static unsigned long eurwdt_is_open;
62 static int eurwdt_timeout;
63 static char eur_expect_close;
64 static DEFINE_SPINLOCK(eurwdt_lock);
65 
66 /*
67  * You must set these - there is no sane way to probe for this board.
68  */
69 
70 static int io = 0x3f0;
71 static int irq = 10;
72 static char *ev = "int";
73 
74 #define WDT_TIMEOUT		60                /* 1 minute */
75 
76 static bool nowayout = WATCHDOG_NOWAYOUT;
77 module_param(nowayout, bool, 0);
78 MODULE_PARM_DESC(nowayout,
79 		"Watchdog cannot be stopped once started (default="
80 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
81 
82 /*
83  * Some symbolic names
84  */
85 
86 #define WDT_CTRL_REG		0x30
87 #define WDT_OUTPIN_CFG		0xe2
88 #define WDT_EVENT_INT		0x00
89 #define WDT_EVENT_REBOOT	0x08
90 #define WDT_UNIT_SEL		0xf1
91 #define WDT_UNIT_SECS		0x80
92 #define WDT_TIMEOUT_VAL		0xf2
93 #define WDT_TIMER_CFG		0xf3
94 
95 
96 module_param_hw(io, int, ioport, 0);
97 MODULE_PARM_DESC(io, "Eurotech WDT io port (default=0x3f0)");
98 module_param_hw(irq, int, irq, 0);
99 MODULE_PARM_DESC(irq, "Eurotech WDT irq (default=10)");
100 module_param(ev, charp, 0);
101 MODULE_PARM_DESC(ev, "Eurotech WDT event type (default is `int')");
102 
103 
104 /*
105  * Programming support
106  */
107 
108 static inline void eurwdt_write_reg(u8 index, u8 data)
109 {
110 	outb(index, io);
111 	outb(data, io+1);
112 }
113 
114 static inline void eurwdt_lock_chip(void)
115 {
116 	outb(0xaa, io);
117 }
118 
119 static inline void eurwdt_unlock_chip(void)
120 {
121 	outb(0x55, io);
122 	eurwdt_write_reg(0x07, 0x08);	/* set the logical device */
123 }
124 
125 static inline void eurwdt_set_timeout(int timeout)
126 {
127 	eurwdt_write_reg(WDT_TIMEOUT_VAL, (u8) timeout);
128 }
129 
130 static inline void eurwdt_disable_timer(void)
131 {
132 	eurwdt_set_timeout(0);
133 }
134 
135 static void eurwdt_activate_timer(void)
136 {
137 	eurwdt_disable_timer();
138 	eurwdt_write_reg(WDT_CTRL_REG, 0x01);	/* activate the WDT */
139 	eurwdt_write_reg(WDT_OUTPIN_CFG,
140 		!strcmp("int", ev) ? WDT_EVENT_INT : WDT_EVENT_REBOOT);
141 
142 	/* Setting interrupt line */
143 	if (irq == 2 || irq > 15 || irq < 0) {
144 		pr_err("invalid irq number\n");
145 		irq = 0;	/* if invalid we disable interrupt */
146 	}
147 	if (irq == 0)
148 		pr_info("interrupt disabled\n");
149 
150 	eurwdt_write_reg(WDT_TIMER_CFG, irq << 4);
151 
152 	eurwdt_write_reg(WDT_UNIT_SEL, WDT_UNIT_SECS);	/* we use seconds */
153 	eurwdt_set_timeout(0);	/* the default timeout */
154 }
155 
156 
157 /*
158  * Kernel methods.
159  */
160 
161 static irqreturn_t eurwdt_interrupt(int irq, void *dev_id)
162 {
163 	pr_crit("timeout WDT timeout\n");
164 
165 #ifdef ONLY_TESTING
166 	pr_crit("Would Reboot\n");
167 #else
168 	pr_crit("Initiating system reboot\n");
169 	emergency_restart();
170 #endif
171 	return IRQ_HANDLED;
172 }
173 
174 
175 /**
176  * eurwdt_ping:
177  *
178  * Reload counter one with the watchdog timeout.
179  */
180 
181 static void eurwdt_ping(void)
182 {
183 	/* Write the watchdog default value */
184 	eurwdt_set_timeout(eurwdt_timeout);
185 }
186 
187 /**
188  * eurwdt_write:
189  * @file: file handle to the watchdog
190  * @buf: buffer to write (unused as data does not matter here
191  * @count: count of bytes
192  * @ppos: pointer to the position to write. No seeks allowed
193  *
194  * A write to a watchdog device is defined as a keepalive signal. Any
195  * write of data will do, as we we don't define content meaning.
196  */
197 
198 static ssize_t eurwdt_write(struct file *file, const char __user *buf,
199 size_t count, loff_t *ppos)
200 {
201 	if (count) {
202 		if (!nowayout) {
203 			size_t i;
204 
205 			eur_expect_close = 0;
206 
207 			for (i = 0; i != count; i++) {
208 				char c;
209 				if (get_user(c, buf + i))
210 					return -EFAULT;
211 				if (c == 'V')
212 					eur_expect_close = 42;
213 			}
214 		}
215 		spin_lock(&eurwdt_lock);
216 		eurwdt_ping();	/* the default timeout */
217 		spin_unlock(&eurwdt_lock);
218 	}
219 	return count;
220 }
221 
222 /**
223  * eurwdt_ioctl:
224  * @file: file handle to the device
225  * @cmd: watchdog command
226  * @arg: argument pointer
227  *
228  * The watchdog API defines a common set of functions for all watchdogs
229  * according to their available features.
230  */
231 
232 static long eurwdt_ioctl(struct file *file,
233 					unsigned int cmd, unsigned long arg)
234 {
235 	void __user *argp = (void __user *)arg;
236 	int __user *p = argp;
237 	static const struct watchdog_info ident = {
238 		.options	  = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
239 							| WDIOF_MAGICCLOSE,
240 		.firmware_version = 1,
241 		.identity	  = "WDT Eurotech CPU-1220/1410",
242 	};
243 
244 	int time;
245 	int options, retval = -EINVAL;
246 
247 	switch (cmd) {
248 	case WDIOC_GETSUPPORT:
249 		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
250 
251 	case WDIOC_GETSTATUS:
252 	case WDIOC_GETBOOTSTATUS:
253 		return put_user(0, p);
254 
255 	case WDIOC_SETOPTIONS:
256 		if (get_user(options, p))
257 			return -EFAULT;
258 		spin_lock(&eurwdt_lock);
259 		if (options & WDIOS_DISABLECARD) {
260 			eurwdt_disable_timer();
261 			retval = 0;
262 		}
263 		if (options & WDIOS_ENABLECARD) {
264 			eurwdt_activate_timer();
265 			eurwdt_ping();
266 			retval = 0;
267 		}
268 		spin_unlock(&eurwdt_lock);
269 		return retval;
270 
271 	case WDIOC_KEEPALIVE:
272 		spin_lock(&eurwdt_lock);
273 		eurwdt_ping();
274 		spin_unlock(&eurwdt_lock);
275 		return 0;
276 
277 	case WDIOC_SETTIMEOUT:
278 		if (copy_from_user(&time, p, sizeof(int)))
279 			return -EFAULT;
280 
281 		/* Sanity check */
282 		if (time < 0 || time > 255)
283 			return -EINVAL;
284 
285 		spin_lock(&eurwdt_lock);
286 		eurwdt_timeout = time;
287 		eurwdt_set_timeout(time);
288 		spin_unlock(&eurwdt_lock);
289 		/* fall through */
290 
291 	case WDIOC_GETTIMEOUT:
292 		return put_user(eurwdt_timeout, p);
293 
294 	default:
295 		return -ENOTTY;
296 	}
297 }
298 
299 /**
300  * eurwdt_open:
301  * @inode: inode of device
302  * @file: file handle to device
303  *
304  * The misc device has been opened. The watchdog device is single
305  * open and on opening we load the counter.
306  */
307 
308 static int eurwdt_open(struct inode *inode, struct file *file)
309 {
310 	if (test_and_set_bit(0, &eurwdt_is_open))
311 		return -EBUSY;
312 	eurwdt_timeout = WDT_TIMEOUT;	/* initial timeout */
313 	/* Activate the WDT */
314 	eurwdt_activate_timer();
315 	return stream_open(inode, file);
316 }
317 
318 /**
319  * eurwdt_release:
320  * @inode: inode to board
321  * @file: file handle to board
322  *
323  * The watchdog has a configurable API. There is a religious dispute
324  * between people who want their watchdog to be able to shut down and
325  * those who want to be sure if the watchdog manager dies the machine
326  * reboots. In the former case we disable the counters, in the latter
327  * case you have to open it again very soon.
328  */
329 
330 static int eurwdt_release(struct inode *inode, struct file *file)
331 {
332 	if (eur_expect_close == 42)
333 		eurwdt_disable_timer();
334 	else {
335 		pr_crit("Unexpected close, not stopping watchdog!\n");
336 		eurwdt_ping();
337 	}
338 	clear_bit(0, &eurwdt_is_open);
339 	eur_expect_close = 0;
340 	return 0;
341 }
342 
343 /**
344  * eurwdt_notify_sys:
345  * @this: our notifier block
346  * @code: the event being reported
347  * @unused: unused
348  *
349  * Our notifier is called on system shutdowns. We want to turn the card
350  * off at reboot otherwise the machine will reboot again during memory
351  * test or worse yet during the following fsck. This would suck, in fact
352  * trust me - if it happens it does suck.
353  */
354 
355 static int eurwdt_notify_sys(struct notifier_block *this, unsigned long code,
356 	void *unused)
357 {
358 	if (code == SYS_DOWN || code == SYS_HALT)
359 		eurwdt_disable_timer();	/* Turn the card off */
360 
361 	return NOTIFY_DONE;
362 }
363 
364 /*
365  * Kernel Interfaces
366  */
367 
368 
369 static const struct file_operations eurwdt_fops = {
370 	.owner		= THIS_MODULE,
371 	.llseek		= no_llseek,
372 	.write		= eurwdt_write,
373 	.unlocked_ioctl	= eurwdt_ioctl,
374 	.open		= eurwdt_open,
375 	.release	= eurwdt_release,
376 };
377 
378 static struct miscdevice eurwdt_miscdev = {
379 	.minor	= WATCHDOG_MINOR,
380 	.name	= "watchdog",
381 	.fops	= &eurwdt_fops,
382 };
383 
384 /*
385  * The WDT card needs to learn about soft shutdowns in order to
386  * turn the timebomb registers off.
387  */
388 
389 static struct notifier_block eurwdt_notifier = {
390 	.notifier_call = eurwdt_notify_sys,
391 };
392 
393 /**
394  * cleanup_module:
395  *
396  * Unload the watchdog. You cannot do this with any file handles open.
397  * If your watchdog is set to continue ticking on close and you unload
398  * it, well it keeps ticking. We won't get the interrupt but the board
399  * will not touch PC memory so all is fine. You just have to load a new
400  * module in 60 seconds or reboot.
401  */
402 
403 static void __exit eurwdt_exit(void)
404 {
405 	eurwdt_lock_chip();
406 
407 	misc_deregister(&eurwdt_miscdev);
408 
409 	unregister_reboot_notifier(&eurwdt_notifier);
410 	release_region(io, 2);
411 	free_irq(irq, NULL);
412 }
413 
414 /**
415  * eurwdt_init:
416  *
417  * Set up the WDT watchdog board. After grabbing the resources
418  * we require we need also to unlock the device.
419  * The open() function will actually kick the board off.
420  */
421 
422 static int __init eurwdt_init(void)
423 {
424 	int ret;
425 
426 	ret = request_irq(irq, eurwdt_interrupt, 0, "eurwdt", NULL);
427 	if (ret) {
428 		pr_err("IRQ %d is not free\n", irq);
429 		goto out;
430 	}
431 
432 	if (!request_region(io, 2, "eurwdt")) {
433 		pr_err("IO %X is not free\n", io);
434 		ret = -EBUSY;
435 		goto outirq;
436 	}
437 
438 	ret = register_reboot_notifier(&eurwdt_notifier);
439 	if (ret) {
440 		pr_err("can't register reboot notifier (err=%d)\n", ret);
441 		goto outreg;
442 	}
443 
444 	ret = misc_register(&eurwdt_miscdev);
445 	if (ret) {
446 		pr_err("can't misc_register on minor=%d\n", WATCHDOG_MINOR);
447 		goto outreboot;
448 	}
449 
450 	eurwdt_unlock_chip();
451 
452 	ret = 0;
453 	pr_info("Eurotech WDT driver 0.01 at %X (Interrupt %d) - timeout event: %s\n",
454 		io, irq, (!strcmp("int", ev) ? "int" : "reboot"));
455 
456 out:
457 	return ret;
458 
459 outreboot:
460 	unregister_reboot_notifier(&eurwdt_notifier);
461 
462 outreg:
463 	release_region(io, 2);
464 
465 outirq:
466 	free_irq(irq, NULL);
467 	goto out;
468 }
469 
470 module_init(eurwdt_init);
471 module_exit(eurwdt_exit);
472 
473 MODULE_AUTHOR("Rodolfo Giometti");
474 MODULE_DESCRIPTION("Driver for Eurotech CPU-1220/1410 on board watchdog");
475 MODULE_LICENSE("GPL");
476