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/pci.h>
32 #include <linux/spinlock.h>
33 
34 #include <asm/uaccess.h>
35 #include <asm/io.h>
36 
37 #define NAME "it8712f_wdt"
38 
39 MODULE_AUTHOR("Jorge Boncompte - DTI2 <jorge@dti2.net>");
40 MODULE_DESCRIPTION("IT8712F Watchdog Driver");
41 MODULE_LICENSE("GPL");
42 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
43 
44 static int max_units = 255;
45 static int margin = 60;		/* in seconds */
46 module_param(margin, int, 0);
47 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
48 
49 static int nowayout = WATCHDOG_NOWAYOUT;
50 module_param(nowayout, int, 0);
51 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
52 
53 static struct semaphore it8712f_wdt_sem;
54 static unsigned expect_close;
55 static spinlock_t io_lock;
56 static unsigned char revision;
57 
58 /* Dog Food address - We use the game port address */
59 static 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
80 #define WDT_RESET_KBD	0x20
81 #define WDT_RESET_MOUSE	0x40
82 #define WDT_RESET_CIR	0x80
83 
84 #define WDT_UNIT_SEC	0x80	/* If 0 in MINUTES */
85 
86 #define WDT_OUT_PWROK	0x10
87 #define WDT_OUT_KRST	0x40
88 
89 static int
90 superio_inb(int reg)
91 {
92 	outb(reg, REG);
93 	return inb(VAL);
94 }
95 
96 static void
97 superio_outb(int val, int reg)
98 {
99 	outb(reg, REG);
100 	outb(val, VAL);
101 }
102 
103 static int
104 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 
114 static inline void
115 superio_select(int ldn)
116 {
117 	outb(LDN, REG);
118 	outb(ldn, VAL);
119 }
120 
121 static inline void
122 superio_enter(void)
123 {
124 	spin_lock(&io_lock);
125 	outb(0x87, REG);
126 	outb(0x01, REG);
127 	outb(0x55, REG);
128 	outb(0x55, REG);
129 }
130 
131 static inline void
132 superio_exit(void)
133 {
134 	outb(0x02, REG);
135 	outb(0x02, VAL);
136 	spin_unlock(&io_lock);
137 }
138 
139 static inline void
140 it8712f_wdt_ping(void)
141 {
142 	inb(address);
143 }
144 
145 static void
146 it8712f_wdt_update_margin(void)
147 {
148 	int config = WDT_OUT_KRST | WDT_OUT_PWROK;
149 	int units = margin;
150 
151 	/* Switch to minutes precision if the configured margin
152 	 * value does not fit within the register width.
153 	 */
154 	if (units <= max_units) {
155 		config |= WDT_UNIT_SEC; /* else UNIT is MINUTES */
156 		printk(KERN_INFO NAME ": timer margin %d seconds\n", units);
157 	} else {
158 		units /= 60;
159 		printk(KERN_INFO NAME ": timer margin %d minutes\n", units);
160 	}
161 	superio_outb(config, WDT_CONFIG);
162 
163 	if (revision >= 0x08)
164 		superio_outb(units >> 8, WDT_TIMEOUT + 1);
165 	superio_outb(units, WDT_TIMEOUT);
166 }
167 
168 static int
169 it8712f_wdt_get_status(void)
170 {
171 	if (superio_inb(WDT_CONTROL) & 0x01)
172 		return WDIOF_CARDRESET;
173 	else
174 		return 0;
175 }
176 
177 static void
178 it8712f_wdt_enable(void)
179 {
180 	printk(KERN_DEBUG NAME ": enabling watchdog timer\n");
181 	superio_enter();
182 	superio_select(LDN_GPIO);
183 
184 	superio_outb(WDT_RESET_GAME, WDT_CONTROL);
185 
186 	it8712f_wdt_update_margin();
187 
188 	superio_exit();
189 
190 	it8712f_wdt_ping();
191 }
192 
193 static void
194 it8712f_wdt_disable(void)
195 {
196 	printk(KERN_DEBUG NAME ": disabling watchdog timer\n");
197 
198 	superio_enter();
199 	superio_select(LDN_GPIO);
200 
201 	superio_outb(0, WDT_CONFIG);
202 	superio_outb(0, WDT_CONTROL);
203 	if (revision >= 0x08)
204 		superio_outb(0, WDT_TIMEOUT + 1);
205 	superio_outb(0, WDT_TIMEOUT);
206 
207 	superio_exit();
208 }
209 
210 static int
211 it8712f_wdt_notify(struct notifier_block *this,
212 		    unsigned long code, void *unused)
213 {
214 	if (code == SYS_HALT || code == SYS_POWER_OFF)
215 		if (!nowayout)
216 			it8712f_wdt_disable();
217 
218 	return NOTIFY_DONE;
219 }
220 
221 static struct notifier_block it8712f_wdt_notifier = {
222 	.notifier_call = it8712f_wdt_notify,
223 };
224 
225 static ssize_t
226 it8712f_wdt_write(struct file *file, const char __user *data,
227 	size_t len, loff_t *ppos)
228 {
229 	/* check for a magic close character */
230 	if (len) {
231 		size_t i;
232 
233 		it8712f_wdt_ping();
234 
235 		expect_close = 0;
236 		for (i = 0; i < len; ++i) {
237 			char c;
238 			if (get_user(c, data+i))
239 				return -EFAULT;
240 			if (c == 'V')
241 				expect_close = 42;
242 		}
243 	}
244 
245 	return len;
246 }
247 
248 static int
249 it8712f_wdt_ioctl(struct inode *inode, struct file *file,
250 	unsigned int cmd, unsigned long arg)
251 {
252 	void __user *argp = (void __user *)arg;
253 	int __user *p = argp;
254 	static struct watchdog_info ident = {
255 		.identity = "IT8712F Watchdog",
256 		.firmware_version = 1,
257 		.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
258 	};
259 	int value;
260 
261 	switch (cmd) {
262 	default:
263 		return -ENOTTY;
264 	case WDIOC_GETSUPPORT:
265 		if (copy_to_user(argp, &ident, sizeof(ident)))
266 			return -EFAULT;
267 		return 0;
268 	case WDIOC_GETSTATUS:
269 		superio_enter();
270 		superio_select(LDN_GPIO);
271 
272 		value = it8712f_wdt_get_status();
273 
274 		superio_exit();
275 
276 		return put_user(value, p);
277 	case WDIOC_GETBOOTSTATUS:
278 		return put_user(0, p);
279 	case WDIOC_KEEPALIVE:
280 		it8712f_wdt_ping();
281 		return 0;
282 	case WDIOC_SETTIMEOUT:
283 		if (get_user(value, p))
284 			return -EFAULT;
285 		if (value < 1)
286 			return -EINVAL;
287 		if (value > (max_units * 60))
288 			return -EINVAL;
289 		margin = value;
290 		superio_enter();
291 		superio_select(LDN_GPIO);
292 
293 		it8712f_wdt_update_margin();
294 
295 		superio_exit();
296 		it8712f_wdt_ping();
297 		/* Fall through */
298 	case WDIOC_GETTIMEOUT:
299 		if (put_user(margin, p))
300 			return -EFAULT;
301 		return 0;
302 	}
303 }
304 
305 static int
306 it8712f_wdt_open(struct inode *inode, struct file *file)
307 {
308 	/* only allow one at a time */
309 	if (down_trylock(&it8712f_wdt_sem))
310 		return -EBUSY;
311 	it8712f_wdt_enable();
312 
313 	return nonseekable_open(inode, file);
314 }
315 
316 static int
317 it8712f_wdt_release(struct inode *inode, struct file *file)
318 {
319 	if (expect_close != 42) {
320 		printk(KERN_WARNING NAME
321 			": watchdog device closed unexpectedly, will not"
322 			" disable the watchdog timer\n");
323 	} else if (!nowayout) {
324 		it8712f_wdt_disable();
325 	}
326 	expect_close = 0;
327 	up(&it8712f_wdt_sem);
328 
329 	return 0;
330 }
331 
332 static const struct file_operations it8712f_wdt_fops = {
333 	.owner = THIS_MODULE,
334 	.llseek = no_llseek,
335 	.write = it8712f_wdt_write,
336 	.ioctl = it8712f_wdt_ioctl,
337 	.open = it8712f_wdt_open,
338 	.release = it8712f_wdt_release,
339 };
340 
341 static struct miscdevice it8712f_wdt_miscdev = {
342 	.minor = WATCHDOG_MINOR,
343 	.name = "watchdog",
344 	.fops = &it8712f_wdt_fops,
345 };
346 
347 static int __init
348 it8712f_wdt_find(unsigned short *address)
349 {
350 	int err = -ENODEV;
351 	int chip_type;
352 
353 	superio_enter();
354 	chip_type = superio_inw(DEVID);
355 	if (chip_type != IT8712F_DEVID)
356 		goto exit;
357 
358 	superio_select(LDN_GAME);
359 	superio_outb(1, ACT_REG);
360 	if (!(superio_inb(ACT_REG) & 0x01)) {
361 		printk(KERN_ERR NAME ": Device not activated, skipping\n");
362 		goto exit;
363 	}
364 
365 	*address = superio_inw(BASE_REG);
366 	if (*address == 0) {
367 		printk(KERN_ERR NAME ": Base address not set, skipping\n");
368 		goto exit;
369 	}
370 
371 	err = 0;
372 	revision = superio_inb(DEVREV) & 0x0f;
373 
374 	/* Later revisions have 16-bit values per datasheet 0.9.1 */
375 	if (revision >= 0x08)
376 		max_units = 65535;
377 
378 	if (margin > (max_units * 60))
379 		margin = (max_units * 60);
380 
381 	printk(KERN_INFO NAME ": Found IT%04xF chip revision %d - "
382 		"using DogFood address 0x%x\n",
383 		chip_type, revision, *address);
384 
385 exit:
386 	superio_exit();
387 	return err;
388 }
389 
390 static int __init
391 it8712f_wdt_init(void)
392 {
393 	int err = 0;
394 
395 	spin_lock_init(&io_lock);
396 
397 	if (it8712f_wdt_find(&address))
398 		return -ENODEV;
399 
400 	if (!request_region(address, 1, "IT8712F Watchdog")) {
401 		printk(KERN_WARNING NAME ": watchdog I/O region busy\n");
402 		return -EBUSY;
403 	}
404 
405 	it8712f_wdt_disable();
406 
407 	sema_init(&it8712f_wdt_sem, 1);
408 
409 	err = register_reboot_notifier(&it8712f_wdt_notifier);
410 	if (err) {
411 		printk(KERN_ERR NAME ": unable to register reboot notifier\n");
412 		goto out;
413 	}
414 
415 	err = misc_register(&it8712f_wdt_miscdev);
416 	if (err) {
417 		printk(KERN_ERR NAME
418 			": cannot register miscdev on minor=%d (err=%d)\n",
419 			WATCHDOG_MINOR, err);
420 		goto reboot_out;
421 	}
422 
423 	return 0;
424 
425 
426 reboot_out:
427 	unregister_reboot_notifier(&it8712f_wdt_notifier);
428 out:
429 	release_region(address, 1);
430 	return err;
431 }
432 
433 static void __exit
434 it8712f_wdt_exit(void)
435 {
436 	misc_deregister(&it8712f_wdt_miscdev);
437 	unregister_reboot_notifier(&it8712f_wdt_notifier);
438 	release_region(address, 1);
439 }
440 
441 module_init(it8712f_wdt_init);
442 module_exit(it8712f_wdt_exit);
443