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(value: reg, REG);
95 return inb(VAL);
96}
97
98static void superio_outb(int val, int reg)
99{
100 outb(value: reg, REG);
101 outb(value: val, VAL);
102}
103
104static int superio_inw(int reg)
105{
106 int val;
107 outb(value: reg++, REG);
108 val = inb(VAL) << 8;
109 outb(value: 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(value: 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(value: 0x87, REG);
129 outb(value: 0x01, REG);
130 outb(value: 0x55, REG);
131 outb(value: 0x55, REG);
132 return 0;
133}
134
135static inline void superio_exit(void)
136{
137 outb(value: 0x02, REG);
138 outb(value: 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(port: 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(val: config, WDT_CONFIG);
164
165 if (revision >= 0x08)
166 superio_outb(val: units >> 8, WDT_TIMEOUT + 1);
167 superio_outb(val: 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(val: 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(val: 0, WDT_CONFIG);
208 superio_outb(val: 0, WDT_CONTROL);
209 if (revision >= 0x08)
210 superio_outb(val: 0, WDT_TIMEOUT + 1);
211 superio_outb(val: 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(to: argp, from: &ident, n: 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(nr: 0, addr: &wdt_open))
320 return -EBUSY;
321
322 ret = it8712f_wdt_enable();
323 if (ret)
324 return ret;
325 return stream_open(inode, filp: 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(nr: 0, addr: &wdt_open);
338
339 return 0;
340}
341
342static const struct file_operations it8712f_wdt_fops = {
343 .owner = THIS_MODULE,
344 .write = it8712f_wdt_write,
345 .unlocked_ioctl = it8712f_wdt_ioctl,
346 .compat_ioctl = compat_ptr_ioctl,
347 .open = it8712f_wdt_open,
348 .release = it8712f_wdt_release,
349};
350
351static struct miscdevice it8712f_wdt_miscdev = {
352 .minor = WATCHDOG_MINOR,
353 .name = "watchdog",
354 .fops = &it8712f_wdt_fops,
355};
356
357static int __init it8712f_wdt_find(unsigned short *address)
358{
359 int err = -ENODEV;
360 int chip_type;
361 int ret = superio_enter();
362 if (ret)
363 return ret;
364
365 chip_type = superio_inw(DEVID);
366 if (chip_type != IT8712F_DEVID)
367 goto exit;
368
369 superio_select(LDN_GAME);
370 superio_outb(val: 1, ACT_REG);
371 if (!(superio_inb(ACT_REG) & 0x01)) {
372 pr_err("Device not activated, skipping\n");
373 goto exit;
374 }
375
376 *address = superio_inw(BASE_REG);
377 if (*address == 0) {
378 pr_err("Base address not set, skipping\n");
379 goto exit;
380 }
381
382 err = 0;
383 revision = superio_inb(DEVREV) & 0x0f;
384
385 /* Later revisions have 16-bit values per datasheet 0.9.1 */
386 if (revision >= 0x08)
387 max_units = 65535;
388
389 if (margin > (max_units * 60))
390 margin = (max_units * 60);
391
392 pr_info("Found IT%04xF chip revision %d - using DogFood address 0x%x\n",
393 chip_type, revision, *address);
394
395exit:
396 superio_exit();
397 return err;
398}
399
400static int __init it8712f_wdt_init(void)
401{
402 int err = 0;
403
404 if (it8712f_wdt_find(address: &address))
405 return -ENODEV;
406
407 if (!request_region(address, 1, "IT8712F Watchdog")) {
408 pr_warn("watchdog I/O region busy\n");
409 return -EBUSY;
410 }
411
412 err = it8712f_wdt_disable();
413 if (err) {
414 pr_err("unable to disable watchdog timer\n");
415 goto out;
416 }
417
418 err = register_reboot_notifier(&it8712f_wdt_notifier);
419 if (err) {
420 pr_err("unable to register reboot notifier\n");
421 goto out;
422 }
423
424 err = misc_register(misc: &it8712f_wdt_miscdev);
425 if (err) {
426 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
427 WATCHDOG_MINOR, err);
428 goto reboot_out;
429 }
430
431 return 0;
432
433
434reboot_out:
435 unregister_reboot_notifier(&it8712f_wdt_notifier);
436out:
437 release_region(address, 1);
438 return err;
439}
440
441static void __exit it8712f_wdt_exit(void)
442{
443 misc_deregister(misc: &it8712f_wdt_miscdev);
444 unregister_reboot_notifier(&it8712f_wdt_notifier);
445 release_region(address, 1);
446}
447
448module_init(it8712f_wdt_init);
449module_exit(it8712f_wdt_exit);
450

source code of linux/drivers/watchdog/it8712f_wdt.c