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 
41 MODULE_AUTHOR("Jorge Boncompte - DTI2 <jorge@dti2.net>");
42 MODULE_DESCRIPTION("IT8712F Watchdog Driver");
43 MODULE_LICENSE("GPL");
44 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
45 
46 static int max_units = 255;
47 static int margin = 60;		/* in seconds */
48 module_param(margin, int, 0);
49 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
50 
51 static bool nowayout = WATCHDOG_NOWAYOUT;
52 module_param(nowayout, bool, 0);
53 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
54 
55 static unsigned long wdt_open;
56 static unsigned expect_close;
57 static unsigned char revision;
58 
59 /* Dog Food address - We use the game port address */
60 static unsigned short address;
61 
62 #define	REG		0x2e	/* The register to read/write */
63 #define	VAL		0x2f	/* The value to read/write */
64 
65 #define	LDN		0x07	/* Register: Logical device select */
66 #define	DEVID		0x20	/* Register: Device ID */
67 #define	DEVREV		0x22	/* Register: Device Revision */
68 #define ACT_REG		0x30	/* LDN Register: Activation */
69 #define BASE_REG	0x60	/* LDN Register: Base address */
70 
71 #define IT8712F_DEVID	0x8712
72 
73 #define LDN_GPIO	0x07	/* GPIO and Watch Dog Timer */
74 #define LDN_GAME	0x09	/* Game Port */
75 
76 #define WDT_CONTROL	0x71	/* WDT Register: Control */
77 #define WDT_CONFIG	0x72	/* WDT Register: Configuration */
78 #define WDT_TIMEOUT	0x73	/* WDT Register: Timeout Value */
79 
80 #define WDT_RESET_GAME	0x10	/* Reset timer on read or write to game port */
81 #define WDT_RESET_KBD	0x20	/* Reset timer on keyboard interrupt */
82 #define WDT_RESET_MOUSE	0x40	/* Reset timer on mouse interrupt */
83 #define WDT_RESET_CIR	0x80	/* Reset timer on consumer IR interrupt */
84 
85 #define WDT_UNIT_SEC	0x80	/* If 0 in MINUTES */
86 
87 #define WDT_OUT_PWROK	0x10	/* Pulse PWROK on timeout */
88 #define WDT_OUT_KRST	0x40	/* Pulse reset on timeout */
89 
90 static int wdt_control_reg = WDT_RESET_GAME;
91 module_param(wdt_control_reg, int, 0);
92 MODULE_PARM_DESC(wdt_control_reg, "Value to write to watchdog control "
93 		"register. The default WDT_RESET_GAME resets the timer on "
94 		"game port reads that this driver generates. You can also "
95 		"use KBD, MOUSE or CIR if you have some external way to "
96 		"generate those interrupts.");
97 
98 static int superio_inb(int reg)
99 {
100 	outb(reg, REG);
101 	return inb(VAL);
102 }
103 
104 static void superio_outb(int val, int reg)
105 {
106 	outb(reg, REG);
107 	outb(val, VAL);
108 }
109 
110 static int superio_inw(int reg)
111 {
112 	int val;
113 	outb(reg++, REG);
114 	val = inb(VAL) << 8;
115 	outb(reg, REG);
116 	val |= inb(VAL);
117 	return val;
118 }
119 
120 static inline void superio_select(int ldn)
121 {
122 	outb(LDN, REG);
123 	outb(ldn, VAL);
124 }
125 
126 static inline int superio_enter(void)
127 {
128 	/*
129 	 * Try to reserve REG and REG + 1 for exclusive access.
130 	 */
131 	if (!request_muxed_region(REG, 2, NAME))
132 		return -EBUSY;
133 
134 	outb(0x87, REG);
135 	outb(0x01, REG);
136 	outb(0x55, REG);
137 	outb(0x55, REG);
138 	return 0;
139 }
140 
141 static inline void superio_exit(void)
142 {
143 	outb(0x02, REG);
144 	outb(0x02, VAL);
145 	release_region(REG, 2);
146 }
147 
148 static inline void it8712f_wdt_ping(void)
149 {
150 	if (wdt_control_reg & WDT_RESET_GAME)
151 		inb(address);
152 }
153 
154 static void it8712f_wdt_update_margin(void)
155 {
156 	int config = WDT_OUT_KRST | WDT_OUT_PWROK;
157 	int units = margin;
158 
159 	/* Switch to minutes precision if the configured margin
160 	 * value does not fit within the register width.
161 	 */
162 	if (units <= max_units) {
163 		config |= WDT_UNIT_SEC; /* else UNIT is MINUTES */
164 		pr_info("timer margin %d seconds\n", units);
165 	} else {
166 		units /= 60;
167 		pr_info("timer margin %d minutes\n", units);
168 	}
169 	superio_outb(config, WDT_CONFIG);
170 
171 	if (revision >= 0x08)
172 		superio_outb(units >> 8, WDT_TIMEOUT + 1);
173 	superio_outb(units, WDT_TIMEOUT);
174 }
175 
176 static int it8712f_wdt_get_status(void)
177 {
178 	if (superio_inb(WDT_CONTROL) & 0x01)
179 		return WDIOF_CARDRESET;
180 	else
181 		return 0;
182 }
183 
184 static int it8712f_wdt_enable(void)
185 {
186 	int ret = superio_enter();
187 	if (ret)
188 		return ret;
189 
190 	pr_debug("enabling watchdog timer\n");
191 	superio_select(LDN_GPIO);
192 
193 	superio_outb(wdt_control_reg, WDT_CONTROL);
194 
195 	it8712f_wdt_update_margin();
196 
197 	superio_exit();
198 
199 	it8712f_wdt_ping();
200 
201 	return 0;
202 }
203 
204 static int it8712f_wdt_disable(void)
205 {
206 	int ret = superio_enter();
207 	if (ret)
208 		return ret;
209 
210 	pr_debug("disabling watchdog timer\n");
211 	superio_select(LDN_GPIO);
212 
213 	superio_outb(0, WDT_CONFIG);
214 	superio_outb(0, WDT_CONTROL);
215 	if (revision >= 0x08)
216 		superio_outb(0, WDT_TIMEOUT + 1);
217 	superio_outb(0, WDT_TIMEOUT);
218 
219 	superio_exit();
220 	return 0;
221 }
222 
223 static int it8712f_wdt_notify(struct notifier_block *this,
224 		    unsigned long code, void *unused)
225 {
226 	if (code == SYS_HALT || code == SYS_POWER_OFF)
227 		if (!nowayout)
228 			it8712f_wdt_disable();
229 
230 	return NOTIFY_DONE;
231 }
232 
233 static struct notifier_block it8712f_wdt_notifier = {
234 	.notifier_call = it8712f_wdt_notify,
235 };
236 
237 static ssize_t it8712f_wdt_write(struct file *file, const char __user *data,
238 					size_t len, loff_t *ppos)
239 {
240 	/* check for a magic close character */
241 	if (len) {
242 		size_t i;
243 
244 		it8712f_wdt_ping();
245 
246 		expect_close = 0;
247 		for (i = 0; i < len; ++i) {
248 			char c;
249 			if (get_user(c, data + i))
250 				return -EFAULT;
251 			if (c == 'V')
252 				expect_close = 42;
253 		}
254 	}
255 
256 	return len;
257 }
258 
259 static long it8712f_wdt_ioctl(struct file *file, unsigned int cmd,
260 							unsigned long arg)
261 {
262 	void __user *argp = (void __user *)arg;
263 	int __user *p = argp;
264 	static const struct watchdog_info ident = {
265 		.identity = "IT8712F Watchdog",
266 		.firmware_version = 1,
267 		.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
268 						WDIOF_MAGICCLOSE,
269 	};
270 	int value;
271 	int ret;
272 
273 	switch (cmd) {
274 	case WDIOC_GETSUPPORT:
275 		if (copy_to_user(argp, &ident, sizeof(ident)))
276 			return -EFAULT;
277 		return 0;
278 	case WDIOC_GETSTATUS:
279 		ret = superio_enter();
280 		if (ret)
281 			return ret;
282 		superio_select(LDN_GPIO);
283 
284 		value = it8712f_wdt_get_status();
285 
286 		superio_exit();
287 
288 		return put_user(value, p);
289 	case WDIOC_GETBOOTSTATUS:
290 		return put_user(0, p);
291 	case WDIOC_KEEPALIVE:
292 		it8712f_wdt_ping();
293 		return 0;
294 	case WDIOC_SETTIMEOUT:
295 		if (get_user(value, p))
296 			return -EFAULT;
297 		if (value < 1)
298 			return -EINVAL;
299 		if (value > (max_units * 60))
300 			return -EINVAL;
301 		margin = value;
302 		ret = superio_enter();
303 		if (ret)
304 			return ret;
305 		superio_select(LDN_GPIO);
306 
307 		it8712f_wdt_update_margin();
308 
309 		superio_exit();
310 		it8712f_wdt_ping();
311 		/* Fall through */
312 	case WDIOC_GETTIMEOUT:
313 		if (put_user(margin, p))
314 			return -EFAULT;
315 		return 0;
316 	default:
317 		return -ENOTTY;
318 	}
319 }
320 
321 static int it8712f_wdt_open(struct inode *inode, struct file *file)
322 {
323 	int ret;
324 	/* only allow one at a time */
325 	if (test_and_set_bit(0, &wdt_open))
326 		return -EBUSY;
327 
328 	ret = it8712f_wdt_enable();
329 	if (ret)
330 		return ret;
331 	return nonseekable_open(inode, file);
332 }
333 
334 static int it8712f_wdt_release(struct inode *inode, struct file *file)
335 {
336 	if (expect_close != 42) {
337 		pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
338 	} else if (!nowayout) {
339 		if (it8712f_wdt_disable())
340 			pr_warn("Watchdog disable failed\n");
341 	}
342 	expect_close = 0;
343 	clear_bit(0, &wdt_open);
344 
345 	return 0;
346 }
347 
348 static const struct file_operations it8712f_wdt_fops = {
349 	.owner = THIS_MODULE,
350 	.llseek = no_llseek,
351 	.write = it8712f_wdt_write,
352 	.unlocked_ioctl = it8712f_wdt_ioctl,
353 	.open = it8712f_wdt_open,
354 	.release = it8712f_wdt_release,
355 };
356 
357 static struct miscdevice it8712f_wdt_miscdev = {
358 	.minor = WATCHDOG_MINOR,
359 	.name = "watchdog",
360 	.fops = &it8712f_wdt_fops,
361 };
362 
363 static int __init it8712f_wdt_find(unsigned short *address)
364 {
365 	int err = -ENODEV;
366 	int chip_type;
367 	int ret = superio_enter();
368 	if (ret)
369 		return ret;
370 
371 	chip_type = superio_inw(DEVID);
372 	if (chip_type != IT8712F_DEVID)
373 		goto exit;
374 
375 	superio_select(LDN_GAME);
376 	superio_outb(1, ACT_REG);
377 	if (!(superio_inb(ACT_REG) & 0x01)) {
378 		pr_err("Device not activated, skipping\n");
379 		goto exit;
380 	}
381 
382 	*address = superio_inw(BASE_REG);
383 	if (*address == 0) {
384 		pr_err("Base address not set, skipping\n");
385 		goto exit;
386 	}
387 
388 	err = 0;
389 	revision = superio_inb(DEVREV) & 0x0f;
390 
391 	/* Later revisions have 16-bit values per datasheet 0.9.1 */
392 	if (revision >= 0x08)
393 		max_units = 65535;
394 
395 	if (margin > (max_units * 60))
396 		margin = (max_units * 60);
397 
398 	pr_info("Found IT%04xF chip revision %d - using DogFood address 0x%x\n",
399 		chip_type, revision, *address);
400 
401 exit:
402 	superio_exit();
403 	return err;
404 }
405 
406 static int __init it8712f_wdt_init(void)
407 {
408 	int err = 0;
409 
410 	if (it8712f_wdt_find(&address))
411 		return -ENODEV;
412 
413 	if (!request_region(address, 1, "IT8712F Watchdog")) {
414 		pr_warn("watchdog I/O region busy\n");
415 		return -EBUSY;
416 	}
417 
418 	err = it8712f_wdt_disable();
419 	if (err) {
420 		pr_err("unable to disable watchdog timer\n");
421 		goto out;
422 	}
423 
424 	err = register_reboot_notifier(&it8712f_wdt_notifier);
425 	if (err) {
426 		pr_err("unable to register reboot notifier\n");
427 		goto out;
428 	}
429 
430 	err = misc_register(&it8712f_wdt_miscdev);
431 	if (err) {
432 		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
433 		       WATCHDOG_MINOR, err);
434 		goto reboot_out;
435 	}
436 
437 	return 0;
438 
439 
440 reboot_out:
441 	unregister_reboot_notifier(&it8712f_wdt_notifier);
442 out:
443 	release_region(address, 1);
444 	return err;
445 }
446 
447 static void __exit it8712f_wdt_exit(void)
448 {
449 	misc_deregister(&it8712f_wdt_miscdev);
450 	unregister_reboot_notifier(&it8712f_wdt_notifier);
451 	release_region(address, 1);
452 }
453 
454 module_init(it8712f_wdt_init);
455 module_exit(it8712f_wdt_exit);
456