1/*
2 *	IT8712F "Smart Guardian" Watchdog support
3 *
4 *	Copyright (c) 2006-2007 Jorge Boncompte - DTI2 <jorge@dti2.net>
5 *
6 *	Based on info and code taken from:
7 *
8 *	drivers/char/watchdog/scx200_wdt.c
9 *	drivers/hwmon/it87.c
10 *	IT8712F EC-LPC I/O Preliminary Specification 0.8.2
11 *	IT8712F EC-LPC I/O Preliminary Specification 0.9.3
12 *
13 *	This program is free software; you can redistribute it and/or
14 *	modify it under the terms of the GNU General Public License as
15 *	published by the Free Software Foundation; either version 2 of the
16 *	License, or (at your option) any later version.
17 *
18 *	The author(s) of this software shall not be held liable for damages
19 *	of any nature resulting due to the use of this software. This
20 *	software is provided AS-IS with no warranties.
21 */
22
23#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
24
25#include <linux/module.h>
26#include <linux/moduleparam.h>
27#include <linux/init.h>
28#include <linux/miscdevice.h>
29#include <linux/watchdog.h>
30#include <linux/notifier.h>
31#include <linux/reboot.h>
32#include <linux/fs.h>
33#include <linux/spinlock.h>
34#include <linux/uaccess.h>
35#include <linux/io.h>
36#include <linux/ioport.h>
37
38#define DEBUG
39#define NAME "it8712f_wdt"
40
41MODULE_AUTHOR("Jorge Boncompte - DTI2 <jorge@dti2.net>");
42MODULE_DESCRIPTION("IT8712F Watchdog Driver");
43MODULE_LICENSE("GPL");
44
45static int max_units = 255;
46static int margin = 60;		/* in seconds */
47module_param(margin, int, 0);
48MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
49
50static bool nowayout = WATCHDOG_NOWAYOUT;
51module_param(nowayout, bool, 0);
52MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
53
54static unsigned long wdt_open;
55static unsigned expect_close;
56static unsigned char revision;
57
58/* Dog Food address - We use the game port address */
59static unsigned short address;
60
61#define	REG		0x2e	/* The register to read/write */
62#define	VAL		0x2f	/* The value to read/write */
63
64#define	LDN		0x07	/* Register: Logical device select */
65#define	DEVID		0x20	/* Register: Device ID */
66#define	DEVREV		0x22	/* Register: Device Revision */
67#define ACT_REG		0x30	/* LDN Register: Activation */
68#define BASE_REG	0x60	/* LDN Register: Base address */
69
70#define IT8712F_DEVID	0x8712
71
72#define LDN_GPIO	0x07	/* GPIO and Watch Dog Timer */
73#define LDN_GAME	0x09	/* Game Port */
74
75#define WDT_CONTROL	0x71	/* WDT Register: Control */
76#define WDT_CONFIG	0x72	/* WDT Register: Configuration */
77#define WDT_TIMEOUT	0x73	/* WDT Register: Timeout Value */
78
79#define WDT_RESET_GAME	0x10	/* Reset timer on read or write to game port */
80#define WDT_RESET_KBD	0x20	/* Reset timer on keyboard interrupt */
81#define WDT_RESET_MOUSE	0x40	/* Reset timer on mouse interrupt */
82#define WDT_RESET_CIR	0x80	/* Reset timer on consumer IR interrupt */
83
84#define WDT_UNIT_SEC	0x80	/* If 0 in MINUTES */
85
86#define WDT_OUT_PWROK	0x10	/* Pulse PWROK on timeout */
87#define WDT_OUT_KRST	0x40	/* Pulse reset on timeout */
88
89static int wdt_control_reg = WDT_RESET_GAME;
90module_param(wdt_control_reg, int, 0);
91MODULE_PARM_DESC(wdt_control_reg, "Value to write to watchdog control "
92		"register. The default WDT_RESET_GAME resets the timer on "
93		"game port reads that this driver generates. You can also "
94		"use KBD, MOUSE or CIR if you have some external way to "
95		"generate those interrupts.");
96
97static int superio_inb(int reg)
98{
99	outb(reg, REG);
100	return inb(VAL);
101}
102
103static void superio_outb(int val, int reg)
104{
105	outb(reg, REG);
106	outb(val, VAL);
107}
108
109static int superio_inw(int reg)
110{
111	int val;
112	outb(reg++, REG);
113	val = inb(VAL) << 8;
114	outb(reg, REG);
115	val |= inb(VAL);
116	return val;
117}
118
119static inline void superio_select(int ldn)
120{
121	outb(LDN, REG);
122	outb(ldn, VAL);
123}
124
125static inline int superio_enter(void)
126{
127	/*
128	 * Try to reserve REG and REG + 1 for exclusive access.
129	 */
130	if (!request_muxed_region(REG, 2, NAME))
131		return -EBUSY;
132
133	outb(0x87, REG);
134	outb(0x01, REG);
135	outb(0x55, REG);
136	outb(0x55, REG);
137	return 0;
138}
139
140static inline void superio_exit(void)
141{
142	outb(0x02, REG);
143	outb(0x02, VAL);
144	release_region(REG, 2);
145}
146
147static inline void it8712f_wdt_ping(void)
148{
149	if (wdt_control_reg & WDT_RESET_GAME)
150		inb(address);
151}
152
153static void it8712f_wdt_update_margin(void)
154{
155	int config = WDT_OUT_KRST | WDT_OUT_PWROK;
156	int units = margin;
157
158	/* Switch to minutes precision if the configured margin
159	 * value does not fit within the register width.
160	 */
161	if (units <= max_units) {
162		config |= WDT_UNIT_SEC; /* else UNIT is MINUTES */
163		pr_info("timer margin %d seconds\n", units);
164	} else {
165		units /= 60;
166		pr_info("timer margin %d minutes\n", units);
167	}
168	superio_outb(config, WDT_CONFIG);
169
170	if (revision >= 0x08)
171		superio_outb(units >> 8, WDT_TIMEOUT + 1);
172	superio_outb(units, WDT_TIMEOUT);
173}
174
175static int it8712f_wdt_get_status(void)
176{
177	if (superio_inb(WDT_CONTROL) & 0x01)
178		return WDIOF_CARDRESET;
179	else
180		return 0;
181}
182
183static int it8712f_wdt_enable(void)
184{
185	int ret = superio_enter();
186	if (ret)
187		return ret;
188
189	pr_debug("enabling watchdog timer\n");
190	superio_select(LDN_GPIO);
191
192	superio_outb(wdt_control_reg, WDT_CONTROL);
193
194	it8712f_wdt_update_margin();
195
196	superio_exit();
197
198	it8712f_wdt_ping();
199
200	return 0;
201}
202
203static int it8712f_wdt_disable(void)
204{
205	int ret = superio_enter();
206	if (ret)
207		return ret;
208
209	pr_debug("disabling watchdog timer\n");
210	superio_select(LDN_GPIO);
211
212	superio_outb(0, WDT_CONFIG);
213	superio_outb(0, WDT_CONTROL);
214	if (revision >= 0x08)
215		superio_outb(0, WDT_TIMEOUT + 1);
216	superio_outb(0, WDT_TIMEOUT);
217
218	superio_exit();
219	return 0;
220}
221
222static int it8712f_wdt_notify(struct notifier_block *this,
223		    unsigned long code, void *unused)
224{
225	if (code == SYS_HALT || code == SYS_POWER_OFF)
226		if (!nowayout)
227			it8712f_wdt_disable();
228
229	return NOTIFY_DONE;
230}
231
232static struct notifier_block it8712f_wdt_notifier = {
233	.notifier_call = it8712f_wdt_notify,
234};
235
236static ssize_t it8712f_wdt_write(struct file *file, const char __user *data,
237					size_t len, loff_t *ppos)
238{
239	/* check for a magic close character */
240	if (len) {
241		size_t i;
242
243		it8712f_wdt_ping();
244
245		expect_close = 0;
246		for (i = 0; i < len; ++i) {
247			char c;
248			if (get_user(c, data + i))
249				return -EFAULT;
250			if (c == 'V')
251				expect_close = 42;
252		}
253	}
254
255	return len;
256}
257
258static long it8712f_wdt_ioctl(struct file *file, unsigned int cmd,
259							unsigned long arg)
260{
261	void __user *argp = (void __user *)arg;
262	int __user *p = argp;
263	static const struct watchdog_info ident = {
264		.identity = "IT8712F Watchdog",
265		.firmware_version = 1,
266		.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
267						WDIOF_MAGICCLOSE,
268	};
269	int value;
270	int ret;
271
272	switch (cmd) {
273	case WDIOC_GETSUPPORT:
274		if (copy_to_user(argp, &ident, sizeof(ident)))
275			return -EFAULT;
276		return 0;
277	case WDIOC_GETSTATUS:
278		ret = superio_enter();
279		if (ret)
280			return ret;
281		superio_select(LDN_GPIO);
282
283		value = it8712f_wdt_get_status();
284
285		superio_exit();
286
287		return put_user(value, p);
288	case WDIOC_GETBOOTSTATUS:
289		return put_user(0, p);
290	case WDIOC_KEEPALIVE:
291		it8712f_wdt_ping();
292		return 0;
293	case WDIOC_SETTIMEOUT:
294		if (get_user(value, p))
295			return -EFAULT;
296		if (value < 1)
297			return -EINVAL;
298		if (value > (max_units * 60))
299			return -EINVAL;
300		margin = value;
301		ret = superio_enter();
302		if (ret)
303			return ret;
304		superio_select(LDN_GPIO);
305
306		it8712f_wdt_update_margin();
307
308		superio_exit();
309		it8712f_wdt_ping();
310		/* Fall through */
311	case WDIOC_GETTIMEOUT:
312		if (put_user(margin, p))
313			return -EFAULT;
314		return 0;
315	default:
316		return -ENOTTY;
317	}
318}
319
320static int it8712f_wdt_open(struct inode *inode, struct file *file)
321{
322	int ret;
323	/* only allow one at a time */
324	if (test_and_set_bit(0, &wdt_open))
325		return -EBUSY;
326
327	ret = it8712f_wdt_enable();
328	if (ret)
329		return ret;
330	return nonseekable_open(inode, file);
331}
332
333static int it8712f_wdt_release(struct inode *inode, struct file *file)
334{
335	if (expect_close != 42) {
336		pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
337	} else if (!nowayout) {
338		if (it8712f_wdt_disable())
339			pr_warn("Watchdog disable failed\n");
340	}
341	expect_close = 0;
342	clear_bit(0, &wdt_open);
343
344	return 0;
345}
346
347static const struct file_operations it8712f_wdt_fops = {
348	.owner = THIS_MODULE,
349	.llseek = no_llseek,
350	.write = it8712f_wdt_write,
351	.unlocked_ioctl = it8712f_wdt_ioctl,
352	.open = it8712f_wdt_open,
353	.release = it8712f_wdt_release,
354};
355
356static struct miscdevice it8712f_wdt_miscdev = {
357	.minor = WATCHDOG_MINOR,
358	.name = "watchdog",
359	.fops = &it8712f_wdt_fops,
360};
361
362static int __init it8712f_wdt_find(unsigned short *address)
363{
364	int err = -ENODEV;
365	int chip_type;
366	int ret = superio_enter();
367	if (ret)
368		return ret;
369
370	chip_type = superio_inw(DEVID);
371	if (chip_type != IT8712F_DEVID)
372		goto exit;
373
374	superio_select(LDN_GAME);
375	superio_outb(1, ACT_REG);
376	if (!(superio_inb(ACT_REG) & 0x01)) {
377		pr_err("Device not activated, skipping\n");
378		goto exit;
379	}
380
381	*address = superio_inw(BASE_REG);
382	if (*address == 0) {
383		pr_err("Base address not set, skipping\n");
384		goto exit;
385	}
386
387	err = 0;
388	revision = superio_inb(DEVREV) & 0x0f;
389
390	/* Later revisions have 16-bit values per datasheet 0.9.1 */
391	if (revision >= 0x08)
392		max_units = 65535;
393
394	if (margin > (max_units * 60))
395		margin = (max_units * 60);
396
397	pr_info("Found IT%04xF chip revision %d - using DogFood address 0x%x\n",
398		chip_type, revision, *address);
399
400exit:
401	superio_exit();
402	return err;
403}
404
405static int __init it8712f_wdt_init(void)
406{
407	int err = 0;
408
409	if (it8712f_wdt_find(&address))
410		return -ENODEV;
411
412	if (!request_region(address, 1, "IT8712F Watchdog")) {
413		pr_warn("watchdog I/O region busy\n");
414		return -EBUSY;
415	}
416
417	err = it8712f_wdt_disable();
418	if (err) {
419		pr_err("unable to disable watchdog timer\n");
420		goto out;
421	}
422
423	err = register_reboot_notifier(&it8712f_wdt_notifier);
424	if (err) {
425		pr_err("unable to register reboot notifier\n");
426		goto out;
427	}
428
429	err = misc_register(&it8712f_wdt_miscdev);
430	if (err) {
431		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
432		       WATCHDOG_MINOR, err);
433		goto reboot_out;
434	}
435
436	return 0;
437
438
439reboot_out:
440	unregister_reboot_notifier(&it8712f_wdt_notifier);
441out:
442	release_region(address, 1);
443	return err;
444}
445
446static void __exit it8712f_wdt_exit(void)
447{
448	misc_deregister(&it8712f_wdt_miscdev);
449	unregister_reboot_notifier(&it8712f_wdt_notifier);
450	release_region(address, 1);
451}
452
453module_init(it8712f_wdt_init);
454module_exit(it8712f_wdt_exit);
455