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 #include <linux/module.h>
24 #include <linux/moduleparam.h>
25 #include <linux/init.h>
26 #include <linux/miscdevice.h>
27 #include <linux/watchdog.h>
28 #include <linux/notifier.h>
29 #include <linux/reboot.h>
30 #include <linux/fs.h>
31 #include <linux/spinlock.h>
32 #include <linux/uaccess.h>
33 #include <linux/io.h>
34 #include <linux/ioport.h>
35 
36 #define NAME "it8712f_wdt"
37 
38 MODULE_AUTHOR("Jorge Boncompte - DTI2 <jorge@dti2.net>");
39 MODULE_DESCRIPTION("IT8712F Watchdog Driver");
40 MODULE_LICENSE("GPL");
41 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
42 
43 static int max_units = 255;
44 static int margin = 60;		/* in seconds */
45 module_param(margin, int, 0);
46 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
47 
48 static int nowayout = WATCHDOG_NOWAYOUT;
49 module_param(nowayout, int, 0);
50 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
51 
52 static unsigned long wdt_open;
53 static unsigned expect_close;
54 static unsigned char revision;
55 
56 /* Dog Food address - We use the game port address */
57 static unsigned short address;
58 
59 #define	REG		0x2e	/* The register to read/write */
60 #define	VAL		0x2f	/* The value to read/write */
61 
62 #define	LDN		0x07	/* Register: Logical device select */
63 #define	DEVID		0x20	/* Register: Device ID */
64 #define	DEVREV		0x22	/* Register: Device Revision */
65 #define ACT_REG		0x30	/* LDN Register: Activation */
66 #define BASE_REG	0x60	/* LDN Register: Base address */
67 
68 #define IT8712F_DEVID	0x8712
69 
70 #define LDN_GPIO	0x07	/* GPIO and Watch Dog Timer */
71 #define LDN_GAME	0x09	/* Game Port */
72 
73 #define WDT_CONTROL	0x71	/* WDT Register: Control */
74 #define WDT_CONFIG	0x72	/* WDT Register: Configuration */
75 #define WDT_TIMEOUT	0x73	/* WDT Register: Timeout Value */
76 
77 #define WDT_RESET_GAME	0x10	/* Reset timer on read or write to game port */
78 #define WDT_RESET_KBD	0x20	/* Reset timer on keyboard interrupt */
79 #define WDT_RESET_MOUSE	0x40	/* Reset timer on mouse interrupt */
80 #define WDT_RESET_CIR	0x80	/* Reset timer on consumer IR interrupt */
81 
82 #define WDT_UNIT_SEC	0x80	/* If 0 in MINUTES */
83 
84 #define WDT_OUT_PWROK	0x10	/* Pulse PWROK on timeout */
85 #define WDT_OUT_KRST	0x40	/* Pulse reset on timeout */
86 
87 static int wdt_control_reg = WDT_RESET_GAME;
88 module_param(wdt_control_reg, int, 0);
89 MODULE_PARM_DESC(wdt_control_reg, "Value to write to watchdog control "
90 		"register. The default WDT_RESET_GAME resets the timer on "
91 		"game port reads that this driver generates. You can also "
92 		"use KBD, MOUSE or CIR if you have some external way to "
93 		"generate those interrupts.");
94 
95 static int superio_inb(int reg)
96 {
97 	outb(reg, REG);
98 	return inb(VAL);
99 }
100 
101 static void superio_outb(int val, int reg)
102 {
103 	outb(reg, REG);
104 	outb(val, VAL);
105 }
106 
107 static int superio_inw(int reg)
108 {
109 	int val;
110 	outb(reg++, REG);
111 	val = inb(VAL) << 8;
112 	outb(reg, REG);
113 	val |= inb(VAL);
114 	return val;
115 }
116 
117 static inline void superio_select(int ldn)
118 {
119 	outb(LDN, REG);
120 	outb(ldn, VAL);
121 }
122 
123 static inline int superio_enter(void)
124 {
125 	/*
126 	 * Try to reserve REG and REG + 1 for exclusive access.
127 	 */
128 	if (!request_muxed_region(REG, 2, NAME))
129 		return -EBUSY;
130 
131 	outb(0x87, REG);
132 	outb(0x01, REG);
133 	outb(0x55, REG);
134 	outb(0x55, REG);
135 	return 0;
136 }
137 
138 static inline void superio_exit(void)
139 {
140 	outb(0x02, REG);
141 	outb(0x02, VAL);
142 	release_region(REG, 2);
143 }
144 
145 static inline void it8712f_wdt_ping(void)
146 {
147 	if (wdt_control_reg & WDT_RESET_GAME)
148 		inb(address);
149 }
150 
151 static void it8712f_wdt_update_margin(void)
152 {
153 	int config = WDT_OUT_KRST | WDT_OUT_PWROK;
154 	int units = margin;
155 
156 	/* Switch to minutes precision if the configured margin
157 	 * value does not fit within the register width.
158 	 */
159 	if (units <= max_units) {
160 		config |= WDT_UNIT_SEC; /* else UNIT is MINUTES */
161 		printk(KERN_INFO NAME ": timer margin %d seconds\n", units);
162 	} else {
163 		units /= 60;
164 		printk(KERN_INFO NAME ": timer margin %d minutes\n", units);
165 	}
166 	superio_outb(config, WDT_CONFIG);
167 
168 	if (revision >= 0x08)
169 		superio_outb(units >> 8, WDT_TIMEOUT + 1);
170 	superio_outb(units, WDT_TIMEOUT);
171 }
172 
173 static int it8712f_wdt_get_status(void)
174 {
175 	if (superio_inb(WDT_CONTROL) & 0x01)
176 		return WDIOF_CARDRESET;
177 	else
178 		return 0;
179 }
180 
181 static int it8712f_wdt_enable(void)
182 {
183 	int ret = superio_enter();
184 	if (ret)
185 		return ret;
186 
187 	printk(KERN_DEBUG NAME ": enabling watchdog timer\n");
188 	superio_select(LDN_GPIO);
189 
190 	superio_outb(wdt_control_reg, WDT_CONTROL);
191 
192 	it8712f_wdt_update_margin();
193 
194 	superio_exit();
195 
196 	it8712f_wdt_ping();
197 
198 	return 0;
199 }
200 
201 static int it8712f_wdt_disable(void)
202 {
203 	int ret = superio_enter();
204 	if (ret)
205 		return ret;
206 
207 	printk(KERN_DEBUG NAME ": disabling watchdog timer\n");
208 	superio_select(LDN_GPIO);
209 
210 	superio_outb(0, WDT_CONFIG);
211 	superio_outb(0, WDT_CONTROL);
212 	if (revision >= 0x08)
213 		superio_outb(0, WDT_TIMEOUT + 1);
214 	superio_outb(0, WDT_TIMEOUT);
215 
216 	superio_exit();
217 	return 0;
218 }
219 
220 static int it8712f_wdt_notify(struct notifier_block *this,
221 		    unsigned long code, void *unused)
222 {
223 	if (code == SYS_HALT || code == SYS_POWER_OFF)
224 		if (!nowayout)
225 			it8712f_wdt_disable();
226 
227 	return NOTIFY_DONE;
228 }
229 
230 static struct notifier_block it8712f_wdt_notifier = {
231 	.notifier_call = it8712f_wdt_notify,
232 };
233 
234 static ssize_t it8712f_wdt_write(struct file *file, const char __user *data,
235 					size_t len, loff_t *ppos)
236 {
237 	/* check for a magic close character */
238 	if (len) {
239 		size_t i;
240 
241 		it8712f_wdt_ping();
242 
243 		expect_close = 0;
244 		for (i = 0; i < len; ++i) {
245 			char c;
246 			if (get_user(c, data + i))
247 				return -EFAULT;
248 			if (c == 'V')
249 				expect_close = 42;
250 		}
251 	}
252 
253 	return len;
254 }
255 
256 static long it8712f_wdt_ioctl(struct file *file, unsigned int cmd,
257 							unsigned long arg)
258 {
259 	void __user *argp = (void __user *)arg;
260 	int __user *p = argp;
261 	static const struct watchdog_info ident = {
262 		.identity = "IT8712F Watchdog",
263 		.firmware_version = 1,
264 		.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
265 						WDIOF_MAGICCLOSE,
266 	};
267 	int value;
268 	int ret;
269 
270 	switch (cmd) {
271 	case WDIOC_GETSUPPORT:
272 		if (copy_to_user(argp, &ident, sizeof(ident)))
273 			return -EFAULT;
274 		return 0;
275 	case WDIOC_GETSTATUS:
276 		ret = superio_enter();
277 		if (ret)
278 			return ret;
279 		superio_select(LDN_GPIO);
280 
281 		value = it8712f_wdt_get_status();
282 
283 		superio_exit();
284 
285 		return put_user(value, p);
286 	case WDIOC_GETBOOTSTATUS:
287 		return put_user(0, p);
288 	case WDIOC_KEEPALIVE:
289 		it8712f_wdt_ping();
290 		return 0;
291 	case WDIOC_SETTIMEOUT:
292 		if (get_user(value, p))
293 			return -EFAULT;
294 		if (value < 1)
295 			return -EINVAL;
296 		if (value > (max_units * 60))
297 			return -EINVAL;
298 		margin = value;
299 		ret = superio_enter();
300 		if (ret)
301 			return ret;
302 		superio_select(LDN_GPIO);
303 
304 		it8712f_wdt_update_margin();
305 
306 		superio_exit();
307 		it8712f_wdt_ping();
308 		/* Fall through */
309 	case WDIOC_GETTIMEOUT:
310 		if (put_user(margin, p))
311 			return -EFAULT;
312 		return 0;
313 	default:
314 		return -ENOTTY;
315 	}
316 }
317 
318 static int it8712f_wdt_open(struct inode *inode, struct file *file)
319 {
320 	int ret;
321 	/* only allow one at a time */
322 	if (test_and_set_bit(0, &wdt_open))
323 		return -EBUSY;
324 
325 	ret = it8712f_wdt_enable();
326 	if (ret)
327 		return ret;
328 	return nonseekable_open(inode, file);
329 }
330 
331 static int it8712f_wdt_release(struct inode *inode, struct file *file)
332 {
333 	if (expect_close != 42) {
334 		printk(KERN_WARNING NAME
335 			": watchdog device closed unexpectedly, will not"
336 			" disable the watchdog timer\n");
337 	} else if (!nowayout) {
338 		if (it8712f_wdt_disable())
339 			printk(KERN_WARNING NAME "Watchdog disable failed\n");
340 	}
341 	expect_close = 0;
342 	clear_bit(0, &wdt_open);
343 
344 	return 0;
345 }
346 
347 static 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 
356 static struct miscdevice it8712f_wdt_miscdev = {
357 	.minor = WATCHDOG_MINOR,
358 	.name = "watchdog",
359 	.fops = &it8712f_wdt_fops,
360 };
361 
362 static 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 		printk(KERN_ERR NAME ": Device not activated, skipping\n");
378 		goto exit;
379 	}
380 
381 	*address = superio_inw(BASE_REG);
382 	if (*address == 0) {
383 		printk(KERN_ERR NAME ": 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 	printk(KERN_INFO NAME ": Found IT%04xF chip revision %d - "
398 		"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 		printk(KERN_WARNING NAME ": watchdog I/O region busy\n");
415 		return -EBUSY;
416 	}
417 
418 	err = it8712f_wdt_disable();
419 	if (err) {
420 		printk(KERN_ERR NAME ": unable to disable watchdog timer.\n");
421 		goto out;
422 	}
423 
424 	err = register_reboot_notifier(&it8712f_wdt_notifier);
425 	if (err) {
426 		printk(KERN_ERR NAME ": unable to register reboot notifier\n");
427 		goto out;
428 	}
429 
430 	err = misc_register(&it8712f_wdt_miscdev);
431 	if (err) {
432 		printk(KERN_ERR NAME
433 			": cannot register miscdev on minor=%d (err=%d)\n",
434 			WATCHDOG_MINOR, err);
435 		goto reboot_out;
436 	}
437 
438 	return 0;
439 
440 
441 reboot_out:
442 	unregister_reboot_notifier(&it8712f_wdt_notifier);
443 out:
444 	release_region(address, 1);
445 	return err;
446 }
447 
448 static void __exit it8712f_wdt_exit(void)
449 {
450 	misc_deregister(&it8712f_wdt_miscdev);
451 	unregister_reboot_notifier(&it8712f_wdt_notifier);
452 	release_region(address, 1);
453 }
454 
455 module_init(it8712f_wdt_init);
456 module_exit(it8712f_wdt_exit);
457