1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Watchdog Timer Driver
4 * for ITE IT87xx Environment Control - Low Pin Count Input / Output
6 * (c) Copyright 2007 Oliver Schuster <olivers137@aol.com>
8 * Based on softdog.c by Alan Cox,
9 * 83977f_wdt.c by Jose Goncalves,
10 * it87.c by Chris Gauthron, Jean Delvare
12 * Data-sheets: Publicly available at the ITE website
13 * http://www.ite.com.tw/
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,
21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
23 #include <linux/init.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>
31 #define WATCHDOG_NAME "IT87 WDT"
33 /* Defaults for Module Parameter */
34 #define DEFAULT_TIMEOUT 60
35 #define DEFAULT_TESTMODE 0
36 #define DEFAULT_NOWAYOUT WATCHDOG_NOWAYOUT
42 /* Logical device Numbers LDN */
45 /* Configuration Registers and Functions */
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 IT8783_ID 0x8783
70 #define IT8786_ID 0x8786
72 /* GPIO Configuration Registers LDN=0x07 */
75 #define WDTVALLSB 0x73
76 #define WDTVALMSB 0x74
78 /* GPIO Bits WDTCFG */
82 #define WDT_PWROK 0x10 /* not in it8721 */
83 #define WDT_INT_MASK 0x0f
85 static unsigned int max_units, chip_type;
87 static unsigned int timeout = DEFAULT_TIMEOUT;
88 static int testmode = DEFAULT_TESTMODE;
89 static bool nowayout = DEFAULT_NOWAYOUT;
91 module_param(timeout, int, 0);
92 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds, default="
93 __MODULE_STRING(DEFAULT_TIMEOUT));
94 module_param(testmode, int, 0);
95 MODULE_PARM_DESC(testmode, "Watchdog test mode (1 = no reboot), default="
96 __MODULE_STRING(DEFAULT_TESTMODE));
97 module_param(nowayout, bool, 0);
98 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started, default="
99 __MODULE_STRING(WATCHDOG_NOWAYOUT));
103 static inline int superio_enter(void)
106 * Try to reserve REG and REG + 1 for exclusive access.
108 if (!request_muxed_region(REG, 2, WATCHDOG_NAME))
118 static inline void superio_exit(void)
122 release_region(REG, 2);
125 static inline void superio_select(int ldn)
131 static inline int superio_inb(int reg)
137 static inline void superio_outb(int val, int reg)
143 static inline int superio_inw(int reg)
153 static inline void superio_outw(int val, int reg)
161 /* Internal function, should be called after superio_select(GPIO) */
162 static void _wdt_update_timeout(unsigned int t)
164 unsigned char cfg = WDT_KRST;
174 if (chip_type != IT8721_ID)
177 superio_outb(cfg, WDTCFG);
178 superio_outb(t, WDTVALLSB);
180 superio_outb(t >> 8, WDTVALMSB);
183 static int wdt_update_timeout(unsigned int t)
187 ret = superio_enter();
191 superio_select(GPIO);
192 _wdt_update_timeout(t);
198 static int wdt_round_time(int t)
205 /* watchdog timer handling */
207 static int wdt_start(struct watchdog_device *wdd)
209 return wdt_update_timeout(wdd->timeout);
212 static int wdt_stop(struct watchdog_device *wdd)
214 return wdt_update_timeout(0);
218 * wdt_set_timeout - set a new timeout value with watchdog ioctl
219 * @t: timeout value in seconds
221 * The hardware device has a 8 or 16 bit watchdog timer (depends on
222 * chip version) that can be configured to count seconds or minutes.
224 * Used within WDIOC_SETTIMEOUT watchdog device ioctl.
227 static int wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
232 t = wdt_round_time(t);
236 if (watchdog_hw_running(wdd))
237 ret = wdt_update_timeout(t);
242 static const struct watchdog_info ident = {
243 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
244 .firmware_version = 1,
245 .identity = WATCHDOG_NAME,
248 static const struct watchdog_ops wdt_ops = {
249 .owner = THIS_MODULE,
252 .set_timeout = wdt_set_timeout,
255 static struct watchdog_device wdt_dev = {
261 static int __init it87_wdt_init(void)
266 rc = superio_enter();
270 chip_type = superio_inw(CHIPID);
271 chip_rev = superio_inb(CHIPREV) & 0x0f;
279 max_units = (chip_rev < 8) ? 255 : 65535;
302 pr_err("Unsupported Chip found, Chip %04x Revision %02x\n",
303 chip_type, chip_rev);
306 pr_err("no device\n");
309 pr_err("Unknown Chip found, Chip %04x Revision %04x\n",
310 chip_type, chip_rev);
314 rc = superio_enter();
318 superio_select(GPIO);
319 superio_outb(WDT_TOV1, WDTCFG);
320 superio_outb(0x00, WDTCTRL);
323 if (timeout < 1 || timeout > max_units * 60) {
324 timeout = DEFAULT_TIMEOUT;
325 pr_warn("Timeout value out of range, use default %d sec\n",
329 if (timeout > max_units)
330 timeout = wdt_round_time(timeout);
332 wdt_dev.timeout = timeout;
333 wdt_dev.max_timeout = max_units * 60;
335 watchdog_stop_on_reboot(&wdt_dev);
336 rc = watchdog_register_device(&wdt_dev);
338 pr_err("Cannot register watchdog device (err=%d)\n", rc);
342 pr_info("Chip IT%04x revision %d initialized. timeout=%d sec (nowayout=%d testmode=%d)\n",
343 chip_type, chip_rev, timeout, nowayout, testmode);
348 static void __exit it87_wdt_exit(void)
350 watchdog_unregister_device(&wdt_dev);
353 module_init(it87_wdt_init);
354 module_exit(it87_wdt_exit);
356 MODULE_AUTHOR("Oliver Schuster");
357 MODULE_DESCRIPTION("Hardware Watchdog Device Driver for IT87xx EC-LPC I/O");
358 MODULE_LICENSE("GPL");