1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *	SMsC 37B787 Watchdog Timer driver for Linux 2.6.x.x
4 *
5 *	Based on acquirewdt.c by Alan Cox <alan@lxorguk.ukuu.org.uk>
6 *	and some other existing drivers
7 *
8 *	The authors do NOT admit liability nor provide warranty for
9 *	any of this software. This material is provided "AS-IS" in
10 *	the hope that it may be useful for others.
11 *
12 *	(C) Copyright 2003-2006  Sven Anders <anders@anduras.de>
13 *
14 *  History:
15 *	2003 - Created version 1.0 for Linux 2.4.x.
16 *	2006 - Ported to Linux 2.6, added nowayout and MAGICCLOSE
17 *	       features. Released version 1.1
18 *
19 *  Theory of operation:
20 *
21 *	A Watchdog Timer (WDT) is a hardware circuit that can
22 *	reset the computer system in case of a software fault.
23 *	You probably knew that already.
24 *
25 *	Usually a userspace daemon will notify the kernel WDT driver
26 *	via the /dev/watchdog special device file that userspace is
27 *	still alive, at regular intervals.  When such a notification
28 *	occurs, the driver will usually tell the hardware watchdog
29 *	that everything is in order, and that the watchdog should wait
30 *	for yet another little while to reset the system.
31 *	If userspace fails (RAM error, kernel bug, whatever), the
32 *	notifications cease to occur, and the hardware watchdog will
33 *	reset the system (causing a reboot) after the timeout occurs.
34 *
35 * Create device with:
36 *  mknod /dev/watchdog c 10 130
37 *
38 * For an example userspace keep-alive daemon, see:
39 *   Documentation/watchdog/wdt.rst
40 */
41
42#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
43
44#include <linux/module.h>
45#include <linux/moduleparam.h>
46#include <linux/types.h>
47#include <linux/miscdevice.h>
48#include <linux/watchdog.h>
49#include <linux/delay.h>
50#include <linux/fs.h>
51#include <linux/ioport.h>
52#include <linux/notifier.h>
53#include <linux/reboot.h>
54#include <linux/init.h>
55#include <linux/spinlock.h>
56#include <linux/io.h>
57#include <linux/uaccess.h>
58
59
60/* enable support for minutes as units? */
61/* (does not always work correctly, so disabled by default!) */
62#define SMSC_SUPPORT_MINUTES
63#undef SMSC_SUPPORT_MINUTES
64
65#define MAX_TIMEOUT     255
66
67#define UNIT_SECOND     0
68#define UNIT_MINUTE     1
69
70#define VERSION		"1.1"
71
72#define IOPORT		0x3F0
73#define IOPORT_SIZE     2
74#define IODEV_NO	8
75
76static int unit = UNIT_SECOND;	/* timer's unit */
77static int timeout = 60;	/* timeout value: default is 60 "units" */
78static unsigned long timer_enabled;   /* is the timer enabled? */
79
80static char expect_close;       /* is the close expected? */
81
82static DEFINE_SPINLOCK(io_lock);/* to guard the watchdog from io races */
83
84static bool nowayout = WATCHDOG_NOWAYOUT;
85
86/* -- Low level function ----------------------------------------*/
87
88/* unlock the IO chip */
89
90static inline void open_io_config(void)
91{
92	outb(0x55, IOPORT);
93	mdelay(1);
94	outb(0x55, IOPORT);
95}
96
97/* lock the IO chip */
98static inline void close_io_config(void)
99{
100	outb(0xAA, IOPORT);
101}
102
103/* select the IO device */
104static inline void select_io_device(unsigned char devno)
105{
106	outb(0x07, IOPORT);
107	outb(devno, IOPORT+1);
108}
109
110/* write to the control register */
111static inline void write_io_cr(unsigned char reg, unsigned char data)
112{
113	outb(reg, IOPORT);
114	outb(data, IOPORT+1);
115}
116
117/* read from the control register */
118static inline char read_io_cr(unsigned char reg)
119{
120	outb(reg, IOPORT);
121	return inb(IOPORT+1);
122}
123
124/* -- Medium level functions ------------------------------------*/
125
126static inline void gpio_bit12(unsigned char reg)
127{
128	/* -- General Purpose I/O Bit 1.2 --
129	 * Bit 0,   In/Out: 0 = Output, 1 = Input
130	 * Bit 1,   Polarity: 0 = No Invert, 1 = Invert
131	 * Bit 2,   Group Enable Intr.: 0 = Disable, 1 = Enable
132	 * Bit 3/4, Function select: 00 = GPI/O, 01 = WDT, 10 = P17,
133	 *                           11 = Either Edge Triggered Intr. 2
134	 * Bit 5/6  (Reserved)
135	 * Bit 7,   Output Type: 0 = Push Pull Bit, 1 = Open Drain
136	 */
137	write_io_cr(0xE2, reg);
138}
139
140static inline void gpio_bit13(unsigned char reg)
141{
142	/* -- General Purpose I/O Bit 1.3 --
143	 * Bit 0,  In/Out: 0 = Output, 1 = Input
144	 * Bit 1,  Polarity: 0 = No Invert, 1 = Invert
145	 * Bit 2,  Group Enable Intr.: 0 = Disable, 1 = Enable
146	 * Bit 3,  Function select: 0 = GPI/O, 1 = LED
147	 * Bit 4-6 (Reserved)
148	 * Bit 7,  Output Type: 0 = Push Pull Bit, 1 = Open Drain
149	 */
150	write_io_cr(0xE3, reg);
151}
152
153static inline void wdt_timer_units(unsigned char new_units)
154{
155	/* -- Watchdog timer units --
156	 * Bit 0-6 (Reserved)
157	 * Bit 7,  WDT Time-out Value Units Select
158	 *         (0 = Minutes, 1 = Seconds)
159	 */
160	write_io_cr(0xF1, new_units);
161}
162
163static inline void wdt_timeout_value(unsigned char new_timeout)
164{
165	/* -- Watchdog Timer Time-out Value --
166	 * Bit 0-7 Binary coded units (0=Disabled, 1..255)
167	 */
168	write_io_cr(0xF2, new_timeout);
169}
170
171static inline void wdt_timer_conf(unsigned char conf)
172{
173	/* -- Watchdog timer configuration --
174	 * Bit 0   Joystick enable: 0* = No Reset, 1 = Reset WDT upon
175	 *							Gameport I/O
176	 * Bit 1   Keyboard enable: 0* = No Reset, 1 = Reset WDT upon KBD Intr.
177	 * Bit 2   Mouse enable: 0* = No Reset, 1 = Reset WDT upon Mouse Intr
178	 * Bit 3   Reset the timer
179	 *         (Wrong in SMsC documentation? Given as: PowerLED Timout
180	 *							Enabled)
181	 * Bit 4-7 WDT Interrupt Mapping: (0000* = Disabled,
182	 *            0001=IRQ1, 0010=(Invalid), 0011=IRQ3 to 1111=IRQ15)
183	 */
184	write_io_cr(0xF3, conf);
185}
186
187static inline void wdt_timer_ctrl(unsigned char reg)
188{
189	/* -- Watchdog timer control --
190	 * Bit 0   Status Bit: 0 = Timer counting, 1 = Timeout occurred
191	 * Bit 1   Power LED Toggle: 0 = Disable Toggle, 1 = Toggle at 1 Hz
192	 * Bit 2   Force Timeout: 1 = Forces WD timeout event (self-cleaning)
193	 * Bit 3   P20 Force Timeout enabled:
194	 *          0 = P20 activity does not generate the WD timeout event
195	 *          1 = P20 Allows rising edge of P20, from the keyboard
196	 *              controller, to force the WD timeout event.
197	 * Bit 4   (Reserved)
198	 * -- Soft power management --
199	 * Bit 5   Stop Counter: 1 = Stop software power down counter
200	 *            set via register 0xB8, (self-cleaning)
201	 *            (Upon read: 0 = Counter running, 1 = Counter stopped)
202	 * Bit 6   Restart Counter: 1 = Restart software power down counter
203	 *            set via register 0xB8, (self-cleaning)
204	 * Bit 7   SPOFF: 1 = Force software power down (self-cleaning)
205	 */
206	write_io_cr(0xF4, reg);
207}
208
209/* -- Higher level functions ------------------------------------*/
210
211/* initialize watchdog */
212
213static void wb_smsc_wdt_initialize(void)
214{
215	unsigned char old;
216
217	spin_lock(&io_lock);
218	open_io_config();
219	select_io_device(IODEV_NO);
220
221	/* enable the watchdog */
222	gpio_bit13(0x08);  /* Select pin 80 = LED not GPIO */
223	gpio_bit12(0x0A);  /* Set pin 79 = WDT not
224			      GPIO/Output/Polarity=Invert */
225	/* disable the timeout */
226	wdt_timeout_value(0);
227
228	/* reset control register */
229	wdt_timer_ctrl(0x00);
230
231	/* reset configuration register */
232	wdt_timer_conf(0x00);
233
234	/* read old (timer units) register */
235	old = read_io_cr(0xF1) & 0x7F;
236	if (unit == UNIT_SECOND)
237		old |= 0x80;	/* set to seconds */
238
239	/* set the watchdog timer units */
240	wdt_timer_units(old);
241
242	close_io_config();
243	spin_unlock(&io_lock);
244}
245
246/* shutdown the watchdog */
247
248static void wb_smsc_wdt_shutdown(void)
249{
250	spin_lock(&io_lock);
251	open_io_config();
252	select_io_device(IODEV_NO);
253
254	/* disable the watchdog */
255	gpio_bit13(0x09);
256	gpio_bit12(0x09);
257
258	/* reset watchdog config register */
259	wdt_timer_conf(0x00);
260
261	/* reset watchdog control register */
262	wdt_timer_ctrl(0x00);
263
264	/* disable timeout */
265	wdt_timeout_value(0x00);
266
267	close_io_config();
268	spin_unlock(&io_lock);
269}
270
271/* set timeout => enable watchdog */
272
273static void wb_smsc_wdt_set_timeout(unsigned char new_timeout)
274{
275	spin_lock(&io_lock);
276	open_io_config();
277	select_io_device(IODEV_NO);
278
279	/* set Power LED to blink, if we enable the timeout */
280	wdt_timer_ctrl((new_timeout == 0) ? 0x00 : 0x02);
281
282	/* set timeout value */
283	wdt_timeout_value(new_timeout);
284
285	close_io_config();
286	spin_unlock(&io_lock);
287}
288
289/* get timeout */
290
291static unsigned char wb_smsc_wdt_get_timeout(void)
292{
293	unsigned char set_timeout;
294
295	spin_lock(&io_lock);
296	open_io_config();
297	select_io_device(IODEV_NO);
298	set_timeout = read_io_cr(0xF2);
299	close_io_config();
300	spin_unlock(&io_lock);
301
302	return set_timeout;
303}
304
305/* disable watchdog */
306
307static void wb_smsc_wdt_disable(void)
308{
309	/* set the timeout to 0 to disable the watchdog */
310	wb_smsc_wdt_set_timeout(0);
311}
312
313/* enable watchdog by setting the current timeout */
314
315static void wb_smsc_wdt_enable(void)
316{
317	/* set the current timeout... */
318	wb_smsc_wdt_set_timeout(timeout);
319}
320
321/* reset the timer */
322
323static void wb_smsc_wdt_reset_timer(void)
324{
325	spin_lock(&io_lock);
326	open_io_config();
327	select_io_device(IODEV_NO);
328
329	/* reset the timer */
330	wdt_timeout_value(timeout);
331	wdt_timer_conf(0x08);
332
333	close_io_config();
334	spin_unlock(&io_lock);
335}
336
337/* return, if the watchdog is enabled (timeout is set...) */
338
339static int wb_smsc_wdt_status(void)
340{
341	return (wb_smsc_wdt_get_timeout() == 0) ? 0 : WDIOF_KEEPALIVEPING;
342}
343
344
345/* -- File operations -------------------------------------------*/
346
347/* open => enable watchdog and set initial timeout */
348
349static int wb_smsc_wdt_open(struct inode *inode, struct file *file)
350{
351	/* /dev/watchdog can only be opened once */
352
353	if (test_and_set_bit(0, &timer_enabled))
354		return -EBUSY;
355
356	if (nowayout)
357		__module_get(THIS_MODULE);
358
359	/* Reload and activate timer */
360	wb_smsc_wdt_enable();
361
362	pr_info("Watchdog enabled. Timeout set to %d %s\n",
363		timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)");
364
365	return stream_open(inode, file);
366}
367
368/* close => shut off the timer */
369
370static int wb_smsc_wdt_release(struct inode *inode, struct file *file)
371{
372	/* Shut off the timer. */
373
374	if (expect_close == 42) {
375		wb_smsc_wdt_disable();
376		pr_info("Watchdog disabled, sleeping again...\n");
377	} else {
378		pr_crit("Unexpected close, not stopping watchdog!\n");
379		wb_smsc_wdt_reset_timer();
380	}
381
382	clear_bit(0, &timer_enabled);
383	expect_close = 0;
384	return 0;
385}
386
387/* write => update the timer to keep the machine alive */
388
389static ssize_t wb_smsc_wdt_write(struct file *file, const char __user *data,
390				 size_t len, loff_t *ppos)
391{
392	/* See if we got the magic character 'V' and reload the timer */
393	if (len) {
394		if (!nowayout) {
395			size_t i;
396
397			/* reset expect flag */
398			expect_close = 0;
399
400			/* scan to see whether or not we got the
401			   magic character */
402			for (i = 0; i != len; i++) {
403				char c;
404				if (get_user(c, data + i))
405					return -EFAULT;
406				if (c == 'V')
407					expect_close = 42;
408			}
409		}
410
411		/* someone wrote to us, we should reload the timer */
412		wb_smsc_wdt_reset_timer();
413	}
414	return len;
415}
416
417/* ioctl => control interface */
418
419static long wb_smsc_wdt_ioctl(struct file *file,
420					unsigned int cmd, unsigned long arg)
421{
422	int new_timeout;
423
424	union {
425		struct watchdog_info __user *ident;
426		int __user *i;
427	} uarg;
428
429	static const struct watchdog_info ident = {
430		.options =		WDIOF_KEEPALIVEPING |
431					WDIOF_SETTIMEOUT |
432					WDIOF_MAGICCLOSE,
433		.firmware_version =	0,
434		.identity =		"SMsC 37B787 Watchdog",
435	};
436
437	uarg.i = (int __user *)arg;
438
439	switch (cmd) {
440	case WDIOC_GETSUPPORT:
441		return copy_to_user(uarg.ident, &ident, sizeof(ident))
442								? -EFAULT : 0;
443	case WDIOC_GETSTATUS:
444		return put_user(wb_smsc_wdt_status(), uarg.i);
445	case WDIOC_GETBOOTSTATUS:
446		return put_user(0, uarg.i);
447	case WDIOC_SETOPTIONS:
448	{
449		int options, retval = -EINVAL;
450
451		if (get_user(options, uarg.i))
452			return -EFAULT;
453
454		if (options & WDIOS_DISABLECARD) {
455			wb_smsc_wdt_disable();
456			retval = 0;
457		}
458		if (options & WDIOS_ENABLECARD) {
459			wb_smsc_wdt_enable();
460			retval = 0;
461		}
462		return retval;
463	}
464	case WDIOC_KEEPALIVE:
465		wb_smsc_wdt_reset_timer();
466		return 0;
467	case WDIOC_SETTIMEOUT:
468		if (get_user(new_timeout, uarg.i))
469			return -EFAULT;
470		/* the API states this is given in secs */
471		if (unit == UNIT_MINUTE)
472			new_timeout /= 60;
473		if (new_timeout < 0 || new_timeout > MAX_TIMEOUT)
474			return -EINVAL;
475		timeout = new_timeout;
476		wb_smsc_wdt_set_timeout(timeout);
477		fallthrough;	/* and return the new timeout */
478	case WDIOC_GETTIMEOUT:
479		new_timeout = timeout;
480		if (unit == UNIT_MINUTE)
481			new_timeout *= 60;
482		return put_user(new_timeout, uarg.i);
483	default:
484		return -ENOTTY;
485	}
486}
487
488/* -- Notifier funtions -----------------------------------------*/
489
490static int wb_smsc_wdt_notify_sys(struct notifier_block *this,
491					unsigned long code, void *unused)
492{
493	if (code == SYS_DOWN || code == SYS_HALT) {
494		/* set timeout to 0, to avoid possible race-condition */
495		timeout = 0;
496		wb_smsc_wdt_disable();
497	}
498	return NOTIFY_DONE;
499}
500
501/* -- Module's structures ---------------------------------------*/
502
503static const struct file_operations wb_smsc_wdt_fops = {
504	.owner	  = THIS_MODULE,
505	.llseek		= no_llseek,
506	.write		= wb_smsc_wdt_write,
507	.unlocked_ioctl	= wb_smsc_wdt_ioctl,
508	.compat_ioctl	= compat_ptr_ioctl,
509	.open		= wb_smsc_wdt_open,
510	.release	= wb_smsc_wdt_release,
511};
512
513static struct notifier_block wb_smsc_wdt_notifier = {
514	.notifier_call  = wb_smsc_wdt_notify_sys,
515};
516
517static struct miscdevice wb_smsc_wdt_miscdev = {
518	.minor		= WATCHDOG_MINOR,
519	.name		= "watchdog",
520	.fops		= &wb_smsc_wdt_fops,
521};
522
523/* -- Module init functions -------------------------------------*/
524
525/* module's "constructor" */
526
527static int __init wb_smsc_wdt_init(void)
528{
529	int ret;
530
531	pr_info("SMsC 37B787 watchdog component driver "
532		VERSION " initialising...\n");
533
534	if (!request_region(IOPORT, IOPORT_SIZE, "SMsC 37B787 watchdog")) {
535		pr_err("Unable to register IO port %#x\n", IOPORT);
536		ret = -EBUSY;
537		goto out_pnp;
538	}
539
540	/* set new maximum, if it's too big */
541	if (timeout > MAX_TIMEOUT)
542		timeout = MAX_TIMEOUT;
543
544	/* init the watchdog timer */
545	wb_smsc_wdt_initialize();
546
547	ret = register_reboot_notifier(&wb_smsc_wdt_notifier);
548	if (ret) {
549		pr_err("Unable to register reboot notifier err = %d\n", ret);
550		goto out_io;
551	}
552
553	ret = misc_register(&wb_smsc_wdt_miscdev);
554	if (ret) {
555		pr_err("Unable to register miscdev on minor %d\n",
556		       WATCHDOG_MINOR);
557		goto out_rbt;
558	}
559
560	/* output info */
561	pr_info("Timeout set to %d %s\n",
562		timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)");
563	pr_info("Watchdog initialized and sleeping (nowayout=%d)...\n",
564		nowayout);
565out_clean:
566	return ret;
567
568out_rbt:
569	unregister_reboot_notifier(&wb_smsc_wdt_notifier);
570
571out_io:
572	release_region(IOPORT, IOPORT_SIZE);
573
574out_pnp:
575	goto out_clean;
576}
577
578/* module's "destructor" */
579
580static void __exit wb_smsc_wdt_exit(void)
581{
582	/* Stop the timer before we leave */
583	if (!nowayout) {
584		wb_smsc_wdt_shutdown();
585		pr_info("Watchdog disabled\n");
586	}
587
588	misc_deregister(&wb_smsc_wdt_miscdev);
589	unregister_reboot_notifier(&wb_smsc_wdt_notifier);
590	release_region(IOPORT, IOPORT_SIZE);
591
592	pr_info("SMsC 37B787 watchdog component driver removed\n");
593}
594
595module_init(wb_smsc_wdt_init);
596module_exit(wb_smsc_wdt_exit);
597
598MODULE_AUTHOR("Sven Anders <anders@anduras.de>");
599MODULE_DESCRIPTION("Driver for SMsC 37B787 watchdog component (Version "
600								VERSION ")");
601MODULE_LICENSE("GPL");
602
603#ifdef SMSC_SUPPORT_MINUTES
604module_param(unit, int, 0);
605MODULE_PARM_DESC(unit,
606		"set unit to use, 0=seconds or 1=minutes, default is 0");
607#endif
608
609module_param(timeout, int, 0);
610MODULE_PARM_DESC(timeout, "range is 1-255 units, default is 60");
611
612module_param(nowayout, bool, 0);
613MODULE_PARM_DESC(nowayout,
614		"Watchdog cannot be stopped once started (default="
615				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
616