1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *	IT8712F "Smart Guardian" Watchdog support
4 *
5 *	Copyright (c) 2006-2007 Jorge Boncompte - DTI2 <jorge@dti2.net>
6 *
7 *	Based on info and code taken from:
8 *
9 *	drivers/char/watchdog/scx200_wdt.c
10 *	drivers/hwmon/it87.c
11 *	IT8712F EC-LPC I/O Preliminary Specification 0.8.2
12 *	IT8712F EC-LPC I/O Preliminary Specification 0.9.3
13 *
14 *	The author(s) of this software shall not be held liable for damages
15 *	of any nature resulting due to the use of this software. This
16 *	software is provided AS-IS with no warranties.
17 */
18
19#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21#include <linux/module.h>
22#include <linux/moduleparam.h>
23#include <linux/init.h>
24#include <linux/miscdevice.h>
25#include <linux/watchdog.h>
26#include <linux/notifier.h>
27#include <linux/reboot.h>
28#include <linux/fs.h>
29#include <linux/spinlock.h>
30#include <linux/uaccess.h>
31#include <linux/io.h>
32#include <linux/ioport.h>
33
34#define NAME "it8712f_wdt"
35
36MODULE_AUTHOR("Jorge Boncompte - DTI2 <jorge@dti2.net>");
37MODULE_DESCRIPTION("IT8712F Watchdog Driver");
38MODULE_LICENSE("GPL");
39
40static int max_units = 255;
41static int margin = 60;		/* in seconds */
42module_param(margin, int, 0);
43MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
44
45static bool nowayout = WATCHDOG_NOWAYOUT;
46module_param(nowayout, bool, 0);
47MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
48
49static unsigned long wdt_open;
50static unsigned expect_close;
51static unsigned char revision;
52
53/* Dog Food address - We use the game port address */
54static unsigned short address;
55
56#define	REG		0x2e	/* The register to read/write */
57#define	VAL		0x2f	/* The value to read/write */
58
59#define	LDN		0x07	/* Register: Logical device select */
60#define	DEVID		0x20	/* Register: Device ID */
61#define	DEVREV		0x22	/* Register: Device Revision */
62#define ACT_REG		0x30	/* LDN Register: Activation */
63#define BASE_REG	0x60	/* LDN Register: Base address */
64
65#define IT8712F_DEVID	0x8712
66
67#define LDN_GPIO	0x07	/* GPIO and Watch Dog Timer */
68#define LDN_GAME	0x09	/* Game Port */
69
70#define WDT_CONTROL	0x71	/* WDT Register: Control */
71#define WDT_CONFIG	0x72	/* WDT Register: Configuration */
72#define WDT_TIMEOUT	0x73	/* WDT Register: Timeout Value */
73
74#define WDT_RESET_GAME	0x10	/* Reset timer on read or write to game port */
75#define WDT_RESET_KBD	0x20	/* Reset timer on keyboard interrupt */
76#define WDT_RESET_MOUSE	0x40	/* Reset timer on mouse interrupt */
77#define WDT_RESET_CIR	0x80	/* Reset timer on consumer IR interrupt */
78
79#define WDT_UNIT_SEC	0x80	/* If 0 in MINUTES */
80
81#define WDT_OUT_PWROK	0x10	/* Pulse PWROK on timeout */
82#define WDT_OUT_KRST	0x40	/* Pulse reset on timeout */
83
84static int wdt_control_reg = WDT_RESET_GAME;
85module_param(wdt_control_reg, int, 0);
86MODULE_PARM_DESC(wdt_control_reg, "Value to write to watchdog control "
87		"register. The default WDT_RESET_GAME resets the timer on "
88		"game port reads that this driver generates. You can also "
89		"use KBD, MOUSE or CIR if you have some external way to "
90		"generate those interrupts.");
91
92static int superio_inb(int reg)
93{
94	outb(reg, REG);
95	return inb(VAL);
96}
97
98static void superio_outb(int val, int reg)
99{
100	outb(reg, REG);
101	outb(val, VAL);
102}
103
104static int superio_inw(int reg)
105{
106	int val;
107	outb(reg++, REG);
108	val = inb(VAL) << 8;
109	outb(reg, REG);
110	val |= inb(VAL);
111	return val;
112}
113
114static inline void superio_select(int ldn)
115{
116	outb(LDN, REG);
117	outb(ldn, VAL);
118}
119
120static inline int superio_enter(void)
121{
122	/*
123	 * Try to reserve REG and REG + 1 for exclusive access.
124	 */
125	if (!request_muxed_region(REG, 2, NAME))
126		return -EBUSY;
127
128	outb(0x87, REG);
129	outb(0x01, REG);
130	outb(0x55, REG);
131	outb(0x55, REG);
132	return 0;
133}
134
135static inline void superio_exit(void)
136{
137	outb(0x02, REG);
138	outb(0x02, VAL);
139	release_region(REG, 2);
140}
141
142static inline void it8712f_wdt_ping(void)
143{
144	if (wdt_control_reg & WDT_RESET_GAME)
145		inb(address);
146}
147
148static void it8712f_wdt_update_margin(void)
149{
150	int config = WDT_OUT_KRST | WDT_OUT_PWROK;
151	int units = margin;
152
153	/* Switch to minutes precision if the configured margin
154	 * value does not fit within the register width.
155	 */
156	if (units <= max_units) {
157		config |= WDT_UNIT_SEC; /* else UNIT is MINUTES */
158		pr_info("timer margin %d seconds\n", units);
159	} else {
160		units /= 60;
161		pr_info("timer margin %d minutes\n", units);
162	}
163	superio_outb(config, WDT_CONFIG);
164
165	if (revision >= 0x08)
166		superio_outb(units >> 8, WDT_TIMEOUT + 1);
167	superio_outb(units, WDT_TIMEOUT);
168}
169
170static int it8712f_wdt_get_status(void)
171{
172	if (superio_inb(WDT_CONTROL) & 0x01)
173		return WDIOF_CARDRESET;
174	else
175		return 0;
176}
177
178static int it8712f_wdt_enable(void)
179{
180	int ret = superio_enter();
181	if (ret)
182		return ret;
183
184	pr_debug("enabling watchdog timer\n");
185	superio_select(LDN_GPIO);
186
187	superio_outb(wdt_control_reg, WDT_CONTROL);
188
189	it8712f_wdt_update_margin();
190
191	superio_exit();
192
193	it8712f_wdt_ping();
194
195	return 0;
196}
197
198static int it8712f_wdt_disable(void)
199{
200	int ret = superio_enter();
201	if (ret)
202		return ret;
203
204	pr_debug("disabling watchdog timer\n");
205	superio_select(LDN_GPIO);
206
207	superio_outb(0, WDT_CONFIG);
208	superio_outb(0, WDT_CONTROL);
209	if (revision >= 0x08)
210		superio_outb(0, WDT_TIMEOUT + 1);
211	superio_outb(0, WDT_TIMEOUT);
212
213	superio_exit();
214	return 0;
215}
216
217static int it8712f_wdt_notify(struct notifier_block *this,
218		    unsigned long code, void *unused)
219{
220	if (code == SYS_HALT || code == SYS_POWER_OFF)
221		if (!nowayout)
222			it8712f_wdt_disable();
223
224	return NOTIFY_DONE;
225}
226
227static struct notifier_block it8712f_wdt_notifier = {
228	.notifier_call = it8712f_wdt_notify,
229};
230
231static ssize_t it8712f_wdt_write(struct file *file, const char __user *data,
232					size_t len, loff_t *ppos)
233{
234	/* check for a magic close character */
235	if (len) {
236		size_t i;
237
238		it8712f_wdt_ping();
239
240		expect_close = 0;
241		for (i = 0; i < len; ++i) {
242			char c;
243			if (get_user(c, data + i))
244				return -EFAULT;
245			if (c == 'V')
246				expect_close = 42;
247		}
248	}
249
250	return len;
251}
252
253static long it8712f_wdt_ioctl(struct file *file, unsigned int cmd,
254							unsigned long arg)
255{
256	void __user *argp = (void __user *)arg;
257	int __user *p = argp;
258	static const struct watchdog_info ident = {
259		.identity = "IT8712F Watchdog",
260		.firmware_version = 1,
261		.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
262						WDIOF_MAGICCLOSE,
263	};
264	int value;
265	int ret;
266
267	switch (cmd) {
268	case WDIOC_GETSUPPORT:
269		if (copy_to_user(argp, &ident, sizeof(ident)))
270			return -EFAULT;
271		return 0;
272	case WDIOC_GETSTATUS:
273		ret = superio_enter();
274		if (ret)
275			return ret;
276		superio_select(LDN_GPIO);
277
278		value = it8712f_wdt_get_status();
279
280		superio_exit();
281
282		return put_user(value, p);
283	case WDIOC_GETBOOTSTATUS:
284		return put_user(0, p);
285	case WDIOC_KEEPALIVE:
286		it8712f_wdt_ping();
287		return 0;
288	case WDIOC_SETTIMEOUT:
289		if (get_user(value, p))
290			return -EFAULT;
291		if (value < 1)
292			return -EINVAL;
293		if (value > (max_units * 60))
294			return -EINVAL;
295		margin = value;
296		ret = superio_enter();
297		if (ret)
298			return ret;
299		superio_select(LDN_GPIO);
300
301		it8712f_wdt_update_margin();
302
303		superio_exit();
304		it8712f_wdt_ping();
305		fallthrough;
306	case WDIOC_GETTIMEOUT:
307		if (put_user(margin, p))
308			return -EFAULT;
309		return 0;
310	default:
311		return -ENOTTY;
312	}
313}
314
315static int it8712f_wdt_open(struct inode *inode, struct file *file)
316{
317	int ret;
318	/* only allow one at a time */
319	if (test_and_set_bit(0, &wdt_open))
320		return -EBUSY;
321
322	ret = it8712f_wdt_enable();
323	if (ret)
324		return ret;
325	return stream_open(inode, file);
326}
327
328static int it8712f_wdt_release(struct inode *inode, struct file *file)
329{
330	if (expect_close != 42) {
331		pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
332	} else if (!nowayout) {
333		if (it8712f_wdt_disable())
334			pr_warn("Watchdog disable failed\n");
335	}
336	expect_close = 0;
337	clear_bit(0, &wdt_open);
338
339	return 0;
340}
341
342static const struct file_operations it8712f_wdt_fops = {
343	.owner = THIS_MODULE,
344	.llseek = no_llseek,
345	.write = it8712f_wdt_write,
346	.unlocked_ioctl = it8712f_wdt_ioctl,
347	.compat_ioctl = compat_ptr_ioctl,
348	.open = it8712f_wdt_open,
349	.release = it8712f_wdt_release,
350};
351
352static struct miscdevice it8712f_wdt_miscdev = {
353	.minor = WATCHDOG_MINOR,
354	.name = "watchdog",
355	.fops = &it8712f_wdt_fops,
356};
357
358static int __init it8712f_wdt_find(unsigned short *address)
359{
360	int err = -ENODEV;
361	int chip_type;
362	int ret = superio_enter();
363	if (ret)
364		return ret;
365
366	chip_type = superio_inw(DEVID);
367	if (chip_type != IT8712F_DEVID)
368		goto exit;
369
370	superio_select(LDN_GAME);
371	superio_outb(1, ACT_REG);
372	if (!(superio_inb(ACT_REG) & 0x01)) {
373		pr_err("Device not activated, skipping\n");
374		goto exit;
375	}
376
377	*address = superio_inw(BASE_REG);
378	if (*address == 0) {
379		pr_err("Base address not set, skipping\n");
380		goto exit;
381	}
382
383	err = 0;
384	revision = superio_inb(DEVREV) & 0x0f;
385
386	/* Later revisions have 16-bit values per datasheet 0.9.1 */
387	if (revision >= 0x08)
388		max_units = 65535;
389
390	if (margin > (max_units * 60))
391		margin = (max_units * 60);
392
393	pr_info("Found IT%04xF chip revision %d - using DogFood address 0x%x\n",
394		chip_type, revision, *address);
395
396exit:
397	superio_exit();
398	return err;
399}
400
401static int __init it8712f_wdt_init(void)
402{
403	int err = 0;
404
405	if (it8712f_wdt_find(&address))
406		return -ENODEV;
407
408	if (!request_region(address, 1, "IT8712F Watchdog")) {
409		pr_warn("watchdog I/O region busy\n");
410		return -EBUSY;
411	}
412
413	err = it8712f_wdt_disable();
414	if (err) {
415		pr_err("unable to disable watchdog timer\n");
416		goto out;
417	}
418
419	err = register_reboot_notifier(&it8712f_wdt_notifier);
420	if (err) {
421		pr_err("unable to register reboot notifier\n");
422		goto out;
423	}
424
425	err = misc_register(&it8712f_wdt_miscdev);
426	if (err) {
427		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
428		       WATCHDOG_MINOR, err);
429		goto reboot_out;
430	}
431
432	return 0;
433
434
435reboot_out:
436	unregister_reboot_notifier(&it8712f_wdt_notifier);
437out:
438	release_region(address, 1);
439	return err;
440}
441
442static void __exit it8712f_wdt_exit(void)
443{
444	misc_deregister(&it8712f_wdt_miscdev);
445	unregister_reboot_notifier(&it8712f_wdt_notifier);
446	release_region(address, 1);
447}
448
449module_init(it8712f_wdt_init);
450module_exit(it8712f_wdt_exit);
451