1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *      NS pc87413-wdt Watchdog Timer driver for Linux 2.6.x.x
4  *
5  *      This code is based on wdt.c with original copyright.
6  *
7  *      (C) Copyright 2006 Sven Anders, <anders@anduras.de>
8  *                     and Marcus Junker, <junker@anduras.de>
9  *
10  *      Neither Sven Anders, Marcus Junker nor ANDURAS AG
11  *      admit liability nor provide warranty for any of this software.
12  *      This material is provided "AS-IS" and at no charge.
13  *
14  *      Release 1.1
15  */
16 
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18 
19 #include <linux/module.h>
20 #include <linux/types.h>
21 #include <linux/miscdevice.h>
22 #include <linux/watchdog.h>
23 #include <linux/ioport.h>
24 #include <linux/delay.h>
25 #include <linux/notifier.h>
26 #include <linux/fs.h>
27 #include <linux/reboot.h>
28 #include <linux/init.h>
29 #include <linux/spinlock.h>
30 #include <linux/moduleparam.h>
31 #include <linux/io.h>
32 #include <linux/uaccess.h>
33 
34 
35 /* #define DEBUG 1 */
36 
37 #define DEFAULT_TIMEOUT     1		/* 1 minute */
38 #define MAX_TIMEOUT         255
39 
40 #define VERSION             "1.1"
41 #define MODNAME             "pc87413 WDT"
42 #define DPFX                MODNAME " - DEBUG: "
43 
44 #define WDT_INDEX_IO_PORT   (io+0)	/* I/O port base (index register) */
45 #define WDT_DATA_IO_PORT    (WDT_INDEX_IO_PORT+1)
46 #define SWC_LDN             0x04
47 #define SIOCFG2             0x22	/* Serial IO register */
48 #define WDCTL               0x10	/* Watchdog-Timer-Control-Register */
49 #define WDTO                0x11	/* Watchdog timeout register */
50 #define WDCFG               0x12	/* Watchdog config register */
51 
52 #define IO_DEFAULT	0x2E		/* Address used on Portwell Boards */
53 
54 static int io = IO_DEFAULT;
55 static int swc_base_addr = -1;
56 
57 static int timeout = DEFAULT_TIMEOUT;	/* timeout value */
58 static unsigned long timer_enabled;	/* is the timer enabled? */
59 
60 static char expect_close;		/* is the close expected? */
61 
62 static DEFINE_SPINLOCK(io_lock);	/* to guard us from io races */
63 
64 static bool nowayout = WATCHDOG_NOWAYOUT;
65 
66 /* -- Low level function ----------------------------------------*/
67 
68 /* Select pins for Watchdog output */
69 
70 static inline void pc87413_select_wdt_out(void)
71 {
72 	unsigned int cr_data = 0;
73 
74 	/* Step 1: Select multiple pin,pin55,as WDT output */
75 
76 	outb_p(SIOCFG2, WDT_INDEX_IO_PORT);
77 
78 	cr_data = inb(WDT_DATA_IO_PORT);
79 
80 	cr_data |= 0x80; /* Set Bit7 to 1*/
81 	outb_p(SIOCFG2, WDT_INDEX_IO_PORT);
82 
83 	outb_p(cr_data, WDT_DATA_IO_PORT);
84 
85 #ifdef DEBUG
86 	pr_info(DPFX
87 		"Select multiple pin,pin55,as WDT output: Bit7 to 1: %d\n",
88 								cr_data);
89 #endif
90 }
91 
92 /* Enable SWC functions */
93 
94 static inline void pc87413_enable_swc(void)
95 {
96 	unsigned int cr_data = 0;
97 
98 	/* Step 2: Enable SWC functions */
99 
100 	outb_p(0x07, WDT_INDEX_IO_PORT);	/* Point SWC_LDN (LDN=4) */
101 	outb_p(SWC_LDN, WDT_DATA_IO_PORT);
102 
103 	outb_p(0x30, WDT_INDEX_IO_PORT);	/* Read Index 0x30 First */
104 	cr_data = inb(WDT_DATA_IO_PORT);
105 	cr_data |= 0x01;			/* Set Bit0 to 1 */
106 	outb_p(0x30, WDT_INDEX_IO_PORT);
107 	outb_p(cr_data, WDT_DATA_IO_PORT);	/* Index0x30_bit0P1 */
108 
109 #ifdef DEBUG
110 	pr_info(DPFX "pc87413 - Enable SWC functions\n");
111 #endif
112 }
113 
114 /* Read SWC I/O base address */
115 
116 static void pc87413_get_swc_base_addr(void)
117 {
118 	unsigned char addr_l, addr_h = 0;
119 
120 	/* Step 3: Read SWC I/O Base Address */
121 
122 	outb_p(0x60, WDT_INDEX_IO_PORT);	/* Read Index 0x60 */
123 	addr_h = inb(WDT_DATA_IO_PORT);
124 
125 	outb_p(0x61, WDT_INDEX_IO_PORT);	/* Read Index 0x61 */
126 
127 	addr_l = inb(WDT_DATA_IO_PORT);
128 
129 	swc_base_addr = (addr_h << 8) + addr_l;
130 #ifdef DEBUG
131 	pr_info(DPFX
132 		"Read SWC I/O Base Address: low %d, high %d, res %d\n",
133 						addr_l, addr_h, swc_base_addr);
134 #endif
135 }
136 
137 /* Select Bank 3 of SWC */
138 
139 static inline void pc87413_swc_bank3(void)
140 {
141 	/* Step 4: Select Bank3 of SWC */
142 	outb_p(inb(swc_base_addr + 0x0f) | 0x03, swc_base_addr + 0x0f);
143 #ifdef DEBUG
144 	pr_info(DPFX "Select Bank3 of SWC\n");
145 #endif
146 }
147 
148 /* Set watchdog timeout to x minutes */
149 
150 static inline void pc87413_programm_wdto(char pc87413_time)
151 {
152 	/* Step 5: Programm WDTO, Twd. */
153 	outb_p(pc87413_time, swc_base_addr + WDTO);
154 #ifdef DEBUG
155 	pr_info(DPFX "Set WDTO to %d minutes\n", pc87413_time);
156 #endif
157 }
158 
159 /* Enable WDEN */
160 
161 static inline void pc87413_enable_wden(void)
162 {
163 	/* Step 6: Enable WDEN */
164 	outb_p(inb(swc_base_addr + WDCTL) | 0x01, swc_base_addr + WDCTL);
165 #ifdef DEBUG
166 	pr_info(DPFX "Enable WDEN\n");
167 #endif
168 }
169 
170 /* Enable SW_WD_TREN */
171 static inline void pc87413_enable_sw_wd_tren(void)
172 {
173 	/* Enable SW_WD_TREN */
174 	outb_p(inb(swc_base_addr + WDCFG) | 0x80, swc_base_addr + WDCFG);
175 #ifdef DEBUG
176 	pr_info(DPFX "Enable SW_WD_TREN\n");
177 #endif
178 }
179 
180 /* Disable SW_WD_TREN */
181 
182 static inline void pc87413_disable_sw_wd_tren(void)
183 {
184 	/* Disable SW_WD_TREN */
185 	outb_p(inb(swc_base_addr + WDCFG) & 0x7f, swc_base_addr + WDCFG);
186 #ifdef DEBUG
187 	pr_info(DPFX "pc87413 - Disable SW_WD_TREN\n");
188 #endif
189 }
190 
191 /* Enable SW_WD_TRG */
192 
193 static inline void pc87413_enable_sw_wd_trg(void)
194 {
195 	/* Enable SW_WD_TRG */
196 	outb_p(inb(swc_base_addr + WDCTL) | 0x80, swc_base_addr + WDCTL);
197 #ifdef DEBUG
198 	pr_info(DPFX "pc87413 - Enable SW_WD_TRG\n");
199 #endif
200 }
201 
202 /* Disable SW_WD_TRG */
203 
204 static inline void pc87413_disable_sw_wd_trg(void)
205 {
206 	/* Disable SW_WD_TRG */
207 	outb_p(inb(swc_base_addr + WDCTL) & 0x7f, swc_base_addr + WDCTL);
208 #ifdef DEBUG
209 	pr_info(DPFX "Disable SW_WD_TRG\n");
210 #endif
211 }
212 
213 /* -- Higher level functions ------------------------------------*/
214 
215 /* Enable the watchdog */
216 
217 static void pc87413_enable(void)
218 {
219 	spin_lock(&io_lock);
220 
221 	pc87413_swc_bank3();
222 	pc87413_programm_wdto(timeout);
223 	pc87413_enable_wden();
224 	pc87413_enable_sw_wd_tren();
225 	pc87413_enable_sw_wd_trg();
226 
227 	spin_unlock(&io_lock);
228 }
229 
230 /* Disable the watchdog */
231 
232 static void pc87413_disable(void)
233 {
234 	spin_lock(&io_lock);
235 
236 	pc87413_swc_bank3();
237 	pc87413_disable_sw_wd_tren();
238 	pc87413_disable_sw_wd_trg();
239 	pc87413_programm_wdto(0);
240 
241 	spin_unlock(&io_lock);
242 }
243 
244 /* Refresh the watchdog */
245 
246 static void pc87413_refresh(void)
247 {
248 	spin_lock(&io_lock);
249 
250 	pc87413_swc_bank3();
251 	pc87413_disable_sw_wd_tren();
252 	pc87413_disable_sw_wd_trg();
253 	pc87413_programm_wdto(timeout);
254 	pc87413_enable_wden();
255 	pc87413_enable_sw_wd_tren();
256 	pc87413_enable_sw_wd_trg();
257 
258 	spin_unlock(&io_lock);
259 }
260 
261 /* -- File operations -------------------------------------------*/
262 
263 /**
264  *	pc87413_open:
265  *	@inode: inode of device
266  *	@file: file handle to device
267  *
268  */
269 
270 static int pc87413_open(struct inode *inode, struct file *file)
271 {
272 	/* /dev/watchdog can only be opened once */
273 
274 	if (test_and_set_bit(0, &timer_enabled))
275 		return -EBUSY;
276 
277 	if (nowayout)
278 		__module_get(THIS_MODULE);
279 
280 	/* Reload and activate timer */
281 	pc87413_refresh();
282 
283 	pr_info("Watchdog enabled. Timeout set to %d minute(s).\n", timeout);
284 
285 	return stream_open(inode, file);
286 }
287 
288 /**
289  *	pc87413_release:
290  *	@inode: inode to board
291  *	@file: file handle to board
292  *
293  *	The watchdog has a configurable API. There is a religious dispute
294  *	between people who want their watchdog to be able to shut down and
295  *	those who want to be sure if the watchdog manager dies the machine
296  *	reboots. In the former case we disable the counters, in the latter
297  *	case you have to open it again very soon.
298  */
299 
300 static int pc87413_release(struct inode *inode, struct file *file)
301 {
302 	/* Shut off the timer. */
303 
304 	if (expect_close == 42) {
305 		pc87413_disable();
306 		pr_info("Watchdog disabled, sleeping again...\n");
307 	} else {
308 		pr_crit("Unexpected close, not stopping watchdog!\n");
309 		pc87413_refresh();
310 	}
311 	clear_bit(0, &timer_enabled);
312 	expect_close = 0;
313 	return 0;
314 }
315 
316 /**
317  *	pc87413_status:
318  *
319  *      return, if the watchdog is enabled (timeout is set...)
320  */
321 
322 
323 static int pc87413_status(void)
324 {
325 	  return 0; /* currently not supported */
326 }
327 
328 /**
329  *	pc87413_write:
330  *	@file: file handle to the watchdog
331  *	@data: data buffer to write
332  *	@len: length in bytes
333  *	@ppos: pointer to the position to write. No seeks allowed
334  *
335  *	A write to a watchdog device is defined as a keepalive signal. Any
336  *	write of data will do, as we we don't define content meaning.
337  */
338 
339 static ssize_t pc87413_write(struct file *file, const char __user *data,
340 			     size_t len, loff_t *ppos)
341 {
342 	/* See if we got the magic character 'V' and reload the timer */
343 	if (len) {
344 		if (!nowayout) {
345 			size_t i;
346 
347 			/* reset expect flag */
348 			expect_close = 0;
349 
350 			/* scan to see whether or not we got the
351 			   magic character */
352 			for (i = 0; i != len; i++) {
353 				char c;
354 				if (get_user(c, data + i))
355 					return -EFAULT;
356 				if (c == 'V')
357 					expect_close = 42;
358 			}
359 		}
360 
361 		/* someone wrote to us, we should reload the timer */
362 		pc87413_refresh();
363 	}
364 	return len;
365 }
366 
367 /**
368  *	pc87413_ioctl:
369  *	@file: file handle to the device
370  *	@cmd: watchdog command
371  *	@arg: argument pointer
372  *
373  *	The watchdog API defines a common set of functions for all watchdogs
374  *	according to their available features. We only actually usefully support
375  *	querying capabilities and current status.
376  */
377 
378 static long pc87413_ioctl(struct file *file, unsigned int cmd,
379 						unsigned long arg)
380 {
381 	int new_timeout;
382 
383 	union {
384 		struct watchdog_info __user *ident;
385 		int __user *i;
386 	} uarg;
387 
388 	static const struct watchdog_info ident = {
389 		.options          = WDIOF_KEEPALIVEPING |
390 				    WDIOF_SETTIMEOUT |
391 				    WDIOF_MAGICCLOSE,
392 		.firmware_version = 1,
393 		.identity         = "PC87413(HF/F) watchdog",
394 	};
395 
396 	uarg.i = (int __user *)arg;
397 
398 	switch (cmd) {
399 	case WDIOC_GETSUPPORT:
400 		return copy_to_user(uarg.ident, &ident,
401 					sizeof(ident)) ? -EFAULT : 0;
402 	case WDIOC_GETSTATUS:
403 		return put_user(pc87413_status(), uarg.i);
404 	case WDIOC_GETBOOTSTATUS:
405 		return put_user(0, uarg.i);
406 	case WDIOC_SETOPTIONS:
407 	{
408 		int options, retval = -EINVAL;
409 		if (get_user(options, uarg.i))
410 			return -EFAULT;
411 		if (options & WDIOS_DISABLECARD) {
412 			pc87413_disable();
413 			retval = 0;
414 		}
415 		if (options & WDIOS_ENABLECARD) {
416 			pc87413_enable();
417 			retval = 0;
418 		}
419 		return retval;
420 	}
421 	case WDIOC_KEEPALIVE:
422 		pc87413_refresh();
423 #ifdef DEBUG
424 		pr_info(DPFX "keepalive\n");
425 #endif
426 		return 0;
427 	case WDIOC_SETTIMEOUT:
428 		if (get_user(new_timeout, uarg.i))
429 			return -EFAULT;
430 		/* the API states this is given in secs */
431 		new_timeout /= 60;
432 		if (new_timeout < 0 || new_timeout > MAX_TIMEOUT)
433 			return -EINVAL;
434 		timeout = new_timeout;
435 		pc87413_refresh();
436 		fallthrough;	/* and return the new timeout */
437 	case WDIOC_GETTIMEOUT:
438 		new_timeout = timeout * 60;
439 		return put_user(new_timeout, uarg.i);
440 	default:
441 		return -ENOTTY;
442 	}
443 }
444 
445 /* -- Notifier functions -----------------------------------------*/
446 
447 /**
448  *	pc87413_notify_sys:
449  *	@this: our notifier block
450  *	@code: the event being reported
451  *	@unused: unused
452  *
453  *	Our notifier is called on system shutdowns. We want to turn the card
454  *	off at reboot otherwise the machine will reboot again during memory
455  *	test or worse yet during the following fsck. This would suck, in fact
456  *	trust me - if it happens it does suck.
457  */
458 
459 static int pc87413_notify_sys(struct notifier_block *this,
460 			      unsigned long code,
461 			      void *unused)
462 {
463 	if (code == SYS_DOWN || code == SYS_HALT)
464 		/* Turn the card off */
465 		pc87413_disable();
466 	return NOTIFY_DONE;
467 }
468 
469 /* -- Module's structures ---------------------------------------*/
470 
471 static const struct file_operations pc87413_fops = {
472 	.owner		= THIS_MODULE,
473 	.llseek		= no_llseek,
474 	.write		= pc87413_write,
475 	.unlocked_ioctl	= pc87413_ioctl,
476 	.compat_ioctl	= compat_ptr_ioctl,
477 	.open		= pc87413_open,
478 	.release	= pc87413_release,
479 };
480 
481 static struct notifier_block pc87413_notifier = {
482 	.notifier_call  = pc87413_notify_sys,
483 };
484 
485 static struct miscdevice pc87413_miscdev = {
486 	.minor          = WATCHDOG_MINOR,
487 	.name           = "watchdog",
488 	.fops           = &pc87413_fops,
489 };
490 
491 /* -- Module init functions -------------------------------------*/
492 
493 /**
494  *	pc87413_init: module's "constructor"
495  *
496  *	Set up the WDT watchdog board. All we have to do is grab the
497  *	resources we require and bitch if anyone beat us to them.
498  *	The open() function will actually kick the board off.
499  */
500 
501 static int __init pc87413_init(void)
502 {
503 	int ret;
504 
505 	pr_info("Version " VERSION " at io 0x%X\n",
506 							WDT_INDEX_IO_PORT);
507 
508 	if (!request_muxed_region(io, 2, MODNAME))
509 		return -EBUSY;
510 
511 	ret = register_reboot_notifier(&pc87413_notifier);
512 	if (ret != 0)
513 		pr_err("cannot register reboot notifier (err=%d)\n", ret);
514 
515 	ret = misc_register(&pc87413_miscdev);
516 	if (ret != 0) {
517 		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
518 		       WATCHDOG_MINOR, ret);
519 		goto reboot_unreg;
520 	}
521 	pr_info("initialized. timeout=%d min\n", timeout);
522 
523 	pc87413_select_wdt_out();
524 	pc87413_enable_swc();
525 	pc87413_get_swc_base_addr();
526 
527 	if (!request_region(swc_base_addr, 0x20, MODNAME)) {
528 		pr_err("cannot request SWC region at 0x%x\n", swc_base_addr);
529 		ret = -EBUSY;
530 		goto misc_unreg;
531 	}
532 
533 	pc87413_enable();
534 
535 	release_region(io, 2);
536 	return 0;
537 
538 misc_unreg:
539 	misc_deregister(&pc87413_miscdev);
540 reboot_unreg:
541 	unregister_reboot_notifier(&pc87413_notifier);
542 	release_region(io, 2);
543 	return ret;
544 }
545 
546 /**
547  *	pc87413_exit: module's "destructor"
548  *
549  *	Unload the watchdog. You cannot do this with any file handles open.
550  *	If your watchdog is set to continue ticking on close and you unload
551  *	it, well it keeps ticking. We won't get the interrupt but the board
552  *	will not touch PC memory so all is fine. You just have to load a new
553  *	module in 60 seconds or reboot.
554  */
555 
556 static void __exit pc87413_exit(void)
557 {
558 	/* Stop the timer before we leave */
559 	if (!nowayout) {
560 		pc87413_disable();
561 		pr_info("Watchdog disabled\n");
562 	}
563 
564 	misc_deregister(&pc87413_miscdev);
565 	unregister_reboot_notifier(&pc87413_notifier);
566 	release_region(swc_base_addr, 0x20);
567 
568 	pr_info("watchdog component driver removed\n");
569 }
570 
571 module_init(pc87413_init);
572 module_exit(pc87413_exit);
573 
574 MODULE_AUTHOR("Sven Anders <anders@anduras.de>");
575 MODULE_AUTHOR("Marcus Junker <junker@anduras.de>");
576 MODULE_DESCRIPTION("PC87413 WDT driver");
577 MODULE_LICENSE("GPL");
578 
579 module_param_hw(io, int, ioport, 0);
580 MODULE_PARM_DESC(io, MODNAME " I/O port (default: "
581 					__MODULE_STRING(IO_DEFAULT) ").");
582 
583 module_param(timeout, int, 0);
584 MODULE_PARM_DESC(timeout,
585 		"Watchdog timeout in minutes (default="
586 				__MODULE_STRING(DEFAULT_TIMEOUT) ").");
587 
588 module_param(nowayout, bool, 0);
589 MODULE_PARM_DESC(nowayout,
590 		"Watchdog cannot be stopped once started (default="
591 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
592 
593