xref: /openbmc/linux/drivers/watchdog/it87_wdt.c (revision f5ad1c74) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *	Watchdog Timer Driver
4  *	   for ITE IT87xx Environment Control - Low Pin Count Input / Output
5  *
6  *	(c) Copyright 2007  Oliver Schuster <olivers137@aol.com>
7  *
8  *	Based on softdog.c	by Alan Cox,
9  *		 83977f_wdt.c	by Jose Goncalves,
10  *		 it87.c		by Chris Gauthron, Jean Delvare
11  *
12  *	Data-sheets: Publicly available at the ITE website
13  *		    http://www.ite.com.tw/
14  *
15  *	Support of the watchdog timers, which are available on
16  *	IT8607, IT8620, IT8622, IT8625, IT8628, IT8655, IT8665, IT8686,
17  *	IT8702, IT8712, IT8716, IT8718, IT8720, IT8721, IT8726, IT8728,
18  *	IT8772, IT8783 and IT8784.
19  */
20 
21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
22 
23 #include <linux/init.h>
24 #include <linux/io.h>
25 #include <linux/kernel.h>
26 #include <linux/module.h>
27 #include <linux/moduleparam.h>
28 #include <linux/types.h>
29 #include <linux/watchdog.h>
30 
31 #define WATCHDOG_NAME		"IT87 WDT"
32 
33 /* Defaults for Module Parameter */
34 #define DEFAULT_TIMEOUT		60
35 #define DEFAULT_TESTMODE	0
36 #define DEFAULT_NOWAYOUT	WATCHDOG_NOWAYOUT
37 
38 /* IO Ports */
39 #define REG		0x2e
40 #define VAL		0x2f
41 
42 /* Logical device Numbers LDN */
43 #define GPIO		0x07
44 
45 /* Configuration Registers and Functions */
46 #define LDNREG		0x07
47 #define CHIPID		0x20
48 #define CHIPREV		0x22
49 
50 /* Chip Id numbers */
51 #define NO_DEV_ID	0xffff
52 #define IT8607_ID	0x8607
53 #define IT8620_ID	0x8620
54 #define IT8622_ID	0x8622
55 #define IT8625_ID	0x8625
56 #define IT8628_ID	0x8628
57 #define IT8655_ID	0x8655
58 #define IT8665_ID	0x8665
59 #define IT8686_ID	0x8686
60 #define IT8702_ID	0x8702
61 #define IT8705_ID	0x8705
62 #define IT8712_ID	0x8712
63 #define IT8716_ID	0x8716
64 #define IT8718_ID	0x8718
65 #define IT8720_ID	0x8720
66 #define IT8721_ID	0x8721
67 #define IT8726_ID	0x8726	/* the data sheet suggest wrongly 0x8716 */
68 #define IT8728_ID	0x8728
69 #define IT8772_ID	0x8772
70 #define IT8783_ID	0x8783
71 #define IT8784_ID	0x8784
72 #define IT8786_ID	0x8786
73 
74 /* GPIO Configuration Registers LDN=0x07 */
75 #define WDTCTRL		0x71
76 #define WDTCFG		0x72
77 #define WDTVALLSB	0x73
78 #define WDTVALMSB	0x74
79 
80 /* GPIO Bits WDTCFG */
81 #define WDT_TOV1	0x80
82 #define WDT_KRST	0x40
83 #define WDT_TOVE	0x20
84 #define WDT_PWROK	0x10 /* not in it8721 */
85 #define WDT_INT_MASK	0x0f
86 
87 static unsigned int max_units, chip_type;
88 
89 static unsigned int timeout = DEFAULT_TIMEOUT;
90 static int testmode = DEFAULT_TESTMODE;
91 static bool nowayout = DEFAULT_NOWAYOUT;
92 
93 module_param(timeout, int, 0);
94 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds, default="
95 		__MODULE_STRING(DEFAULT_TIMEOUT));
96 module_param(testmode, int, 0);
97 MODULE_PARM_DESC(testmode, "Watchdog test mode (1 = no reboot), default="
98 		__MODULE_STRING(DEFAULT_TESTMODE));
99 module_param(nowayout, bool, 0);
100 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started, default="
101 		__MODULE_STRING(WATCHDOG_NOWAYOUT));
102 
103 /* Superio Chip */
104 
105 static inline int superio_enter(void)
106 {
107 	/*
108 	 * Try to reserve REG and REG + 1 for exclusive access.
109 	 */
110 	if (!request_muxed_region(REG, 2, WATCHDOG_NAME))
111 		return -EBUSY;
112 
113 	outb(0x87, REG);
114 	outb(0x01, REG);
115 	outb(0x55, REG);
116 	outb(0x55, REG);
117 	return 0;
118 }
119 
120 static inline void superio_exit(void)
121 {
122 	outb(0x02, REG);
123 	outb(0x02, VAL);
124 	release_region(REG, 2);
125 }
126 
127 static inline void superio_select(int ldn)
128 {
129 	outb(LDNREG, REG);
130 	outb(ldn, VAL);
131 }
132 
133 static inline int superio_inb(int reg)
134 {
135 	outb(reg, REG);
136 	return inb(VAL);
137 }
138 
139 static inline void superio_outb(int val, int reg)
140 {
141 	outb(reg, REG);
142 	outb(val, VAL);
143 }
144 
145 static inline int superio_inw(int reg)
146 {
147 	int val;
148 	outb(reg++, REG);
149 	val = inb(VAL) << 8;
150 	outb(reg, REG);
151 	val |= inb(VAL);
152 	return val;
153 }
154 
155 static inline void superio_outw(int val, int reg)
156 {
157 	outb(reg++, REG);
158 	outb(val >> 8, VAL);
159 	outb(reg, REG);
160 	outb(val, VAL);
161 }
162 
163 /* Internal function, should be called after superio_select(GPIO) */
164 static void _wdt_update_timeout(unsigned int t)
165 {
166 	unsigned char cfg = WDT_KRST;
167 
168 	if (testmode)
169 		cfg = 0;
170 
171 	if (t <= max_units)
172 		cfg |= WDT_TOV1;
173 	else
174 		t /= 60;
175 
176 	if (chip_type != IT8721_ID)
177 		cfg |= WDT_PWROK;
178 
179 	superio_outb(cfg, WDTCFG);
180 	superio_outb(t, WDTVALLSB);
181 	if (max_units > 255)
182 		superio_outb(t >> 8, WDTVALMSB);
183 }
184 
185 static int wdt_update_timeout(unsigned int t)
186 {
187 	int ret;
188 
189 	ret = superio_enter();
190 	if (ret)
191 		return ret;
192 
193 	superio_select(GPIO);
194 	_wdt_update_timeout(t);
195 	superio_exit();
196 
197 	return 0;
198 }
199 
200 static int wdt_round_time(int t)
201 {
202 	t += 59;
203 	t -= t % 60;
204 	return t;
205 }
206 
207 /* watchdog timer handling */
208 
209 static int wdt_start(struct watchdog_device *wdd)
210 {
211 	return wdt_update_timeout(wdd->timeout);
212 }
213 
214 static int wdt_stop(struct watchdog_device *wdd)
215 {
216 	return wdt_update_timeout(0);
217 }
218 
219 /**
220  *	wdt_set_timeout - set a new timeout value with watchdog ioctl
221  *	@t: timeout value in seconds
222  *
223  *	The hardware device has a 8 or 16 bit watchdog timer (depends on
224  *	chip version) that can be configured to count seconds or minutes.
225  *
226  *	Used within WDIOC_SETTIMEOUT watchdog device ioctl.
227  */
228 
229 static int wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
230 {
231 	int ret = 0;
232 
233 	if (t > max_units)
234 		t = wdt_round_time(t);
235 
236 	wdd->timeout = t;
237 
238 	if (watchdog_hw_running(wdd))
239 		ret = wdt_update_timeout(t);
240 
241 	return ret;
242 }
243 
244 static const struct watchdog_info ident = {
245 	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
246 	.firmware_version = 1,
247 	.identity = WATCHDOG_NAME,
248 };
249 
250 static const struct watchdog_ops wdt_ops = {
251 	.owner = THIS_MODULE,
252 	.start = wdt_start,
253 	.stop = wdt_stop,
254 	.set_timeout = wdt_set_timeout,
255 };
256 
257 static struct watchdog_device wdt_dev = {
258 	.info = &ident,
259 	.ops = &wdt_ops,
260 	.min_timeout = 1,
261 };
262 
263 static int __init it87_wdt_init(void)
264 {
265 	u8  chip_rev;
266 	int rc;
267 
268 	rc = superio_enter();
269 	if (rc)
270 		return rc;
271 
272 	chip_type = superio_inw(CHIPID);
273 	chip_rev  = superio_inb(CHIPREV) & 0x0f;
274 	superio_exit();
275 
276 	switch (chip_type) {
277 	case IT8702_ID:
278 		max_units = 255;
279 		break;
280 	case IT8712_ID:
281 		max_units = (chip_rev < 8) ? 255 : 65535;
282 		break;
283 	case IT8716_ID:
284 	case IT8726_ID:
285 		max_units = 65535;
286 		break;
287 	case IT8607_ID:
288 	case IT8620_ID:
289 	case IT8622_ID:
290 	case IT8625_ID:
291 	case IT8628_ID:
292 	case IT8655_ID:
293 	case IT8665_ID:
294 	case IT8686_ID:
295 	case IT8718_ID:
296 	case IT8720_ID:
297 	case IT8721_ID:
298 	case IT8728_ID:
299 	case IT8772_ID:
300 	case IT8783_ID:
301 	case IT8784_ID:
302 	case IT8786_ID:
303 		max_units = 65535;
304 		break;
305 	case IT8705_ID:
306 		pr_err("Unsupported Chip found, Chip %04x Revision %02x\n",
307 		       chip_type, chip_rev);
308 		return -ENODEV;
309 	case NO_DEV_ID:
310 		pr_err("no device\n");
311 		return -ENODEV;
312 	default:
313 		pr_err("Unknown Chip found, Chip %04x Revision %04x\n",
314 		       chip_type, chip_rev);
315 		return -ENODEV;
316 	}
317 
318 	rc = superio_enter();
319 	if (rc)
320 		return rc;
321 
322 	superio_select(GPIO);
323 	superio_outb(WDT_TOV1, WDTCFG);
324 	superio_outb(0x00, WDTCTRL);
325 	superio_exit();
326 
327 	if (timeout < 1 || timeout > max_units * 60) {
328 		timeout = DEFAULT_TIMEOUT;
329 		pr_warn("Timeout value out of range, use default %d sec\n",
330 			DEFAULT_TIMEOUT);
331 	}
332 
333 	if (timeout > max_units)
334 		timeout = wdt_round_time(timeout);
335 
336 	wdt_dev.timeout = timeout;
337 	wdt_dev.max_timeout = max_units * 60;
338 
339 	watchdog_stop_on_reboot(&wdt_dev);
340 	rc = watchdog_register_device(&wdt_dev);
341 	if (rc) {
342 		pr_err("Cannot register watchdog device (err=%d)\n", rc);
343 		return rc;
344 	}
345 
346 	pr_info("Chip IT%04x revision %d initialized. timeout=%d sec (nowayout=%d testmode=%d)\n",
347 		chip_type, chip_rev, timeout, nowayout, testmode);
348 
349 	return 0;
350 }
351 
352 static void __exit it87_wdt_exit(void)
353 {
354 	watchdog_unregister_device(&wdt_dev);
355 }
356 
357 module_init(it87_wdt_init);
358 module_exit(it87_wdt_exit);
359 
360 MODULE_AUTHOR("Oliver Schuster");
361 MODULE_DESCRIPTION("Hardware Watchdog Device Driver for IT87xx EC-LPC I/O");
362 MODULE_LICENSE("GPL");
363