drivers/watchdog/it8712f_wdt.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  IT8712F "Smart Guardian" Watchdog support
0004  *
0005  *  Copyright (c) 2006-2007 Jorge Boncompte - DTI2 <jorge@dti2.net>
0006  *
0007  *  Based on info and code taken from:
0008  *
0009  *  drivers/char/watchdog/scx200_wdt.c
0010  *  drivers/hwmon/it87.c
0011  *  IT8712F EC-LPC I/O Preliminary Specification 0.8.2
0012  *  IT8712F EC-LPC I/O Preliminary Specification 0.9.3
0013  *
0014  *  The author(s) of this software shall not be held liable for damages
0015  *  of any nature resulting due to the use of this software. This
0016  *  software is provided AS-IS with no warranties.
0017  */
0018
0019 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0020
0021 #include <linux/module.h>
0022 #include <linux/moduleparam.h>
0023 #include <linux/init.h>
0024 #include <linux/miscdevice.h>
0025 #include <linux/watchdog.h>
0026 #include <linux/notifier.h>
0027 #include <linux/reboot.h>
0028 #include <linux/fs.h>
0029 #include <linux/spinlock.h>
0030 #include <linux/uaccess.h>
0031 #include <linux/io.h>
0032 #include <linux/ioport.h>
0033
0034 #define NAME "it8712f_wdt"
0035
0036 MODULE_AUTHOR("Jorge Boncompte - DTI2 <jorge@dti2.net>");
0037 MODULE_DESCRIPTION("IT8712F Watchdog Driver");
0038 MODULE_LICENSE("GPL");
0039
0040 static int max_units = 255;
0041 static int margin = 60;     /* in seconds */
0042 module_param(margin, int, 0);
0043 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
0044
0045 static bool nowayout = WATCHDOG_NOWAYOUT;
0046 module_param(nowayout, bool, 0);
0047 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
0048
0049 static unsigned long wdt_open;
0050 static unsigned expect_close;
0051 static unsigned char revision;
0052
0053 /* Dog Food address - We use the game port address */
0054 static unsigned short address;
0055
0056 #define REG     0x2e    /* The register to read/write */
0057 #define VAL     0x2f    /* The value to read/write */
0058
0059 #define LDN     0x07    /* Register: Logical device select */
0060 #define DEVID       0x20    /* Register: Device ID */
0061 #define DEVREV      0x22    /* Register: Device Revision */
0062 #define ACT_REG     0x30    /* LDN Register: Activation */
0063 #define BASE_REG    0x60    /* LDN Register: Base address */
0064
0065 #define IT8712F_DEVID   0x8712
0066
0067 #define LDN_GPIO    0x07    /* GPIO and Watch Dog Timer */
0068 #define LDN_GAME    0x09    /* Game Port */
0069
0070 #define WDT_CONTROL 0x71    /* WDT Register: Control */
0071 #define WDT_CONFIG  0x72    /* WDT Register: Configuration */
0072 #define WDT_TIMEOUT 0x73    /* WDT Register: Timeout Value */
0073
0074 #define WDT_RESET_GAME  0x10    /* Reset timer on read or write to game port */
0075 #define WDT_RESET_KBD   0x20    /* Reset timer on keyboard interrupt */
0076 #define WDT_RESET_MOUSE 0x40    /* Reset timer on mouse interrupt */
0077 #define WDT_RESET_CIR   0x80    /* Reset timer on consumer IR interrupt */
0078
0079 #define WDT_UNIT_SEC    0x80    /* If 0 in MINUTES */
0080
0081 #define WDT_OUT_PWROK   0x10    /* Pulse PWROK on timeout */
0082 #define WDT_OUT_KRST    0x40    /* Pulse reset on timeout */
0083
0084 static int wdt_control_reg = WDT_RESET_GAME;
0085 module_param(wdt_control_reg, int, 0);
0086 MODULE_PARM_DESC(wdt_control_reg, "Value to write to watchdog control "
0087         "register. The default WDT_RESET_GAME resets the timer on "
0088         "game port reads that this driver generates. You can also "
0089         "use KBD, MOUSE or CIR if you have some external way to "
0090         "generate those interrupts.");
0091
0092 static int superio_inb(int reg)
0093 {
0094     outb(reg, REG);
0095     return inb(VAL);
0096 }
0097
0098 static void superio_outb(int val, int reg)
0099 {
0100     outb(reg, REG);
0101     outb(val, VAL);
0102 }
0103
0104 static int superio_inw(int reg)
0105 {
0106     int val;
0107     outb(reg++, REG);
0108     val = inb(VAL) << 8;
0109     outb(reg, REG);
0110     val |= inb(VAL);
0111     return val;
0112 }
0113
0114 static inline void superio_select(int ldn)
0115 {
0116     outb(LDN, REG);
0117     outb(ldn, VAL);
0118 }
0119
0120 static inline int superio_enter(void)
0121 {
0122     /*
0123      * Try to reserve REG and REG + 1 for exclusive access.
0124      */
0125     if (!request_muxed_region(REG, 2, NAME))
0126         return -EBUSY;
0127
0128     outb(0x87, REG);
0129     outb(0x01, REG);
0130     outb(0x55, REG);
0131     outb(0x55, REG);
0132     return 0;
0133 }
0134
0135 static inline void superio_exit(void)
0136 {
0137     outb(0x02, REG);
0138     outb(0x02, VAL);
0139     release_region(REG, 2);
0140 }
0141
0142 static inline void it8712f_wdt_ping(void)
0143 {
0144     if (wdt_control_reg & WDT_RESET_GAME)
0145         inb(address);
0146 }
0147
0148 static void it8712f_wdt_update_margin(void)
0149 {
0150     int config = WDT_OUT_KRST | WDT_OUT_PWROK;
0151     int units = margin;
0152
0153     /* Switch to minutes precision if the configured margin
0154      * value does not fit within the register width.
0155      */
0156     if (units <= max_units) {
0157         config |= WDT_UNIT_SEC; /* else UNIT is MINUTES */
0158         pr_info("timer margin %d seconds\n", units);
0159     } else {
0160         units /= 60;
0161         pr_info("timer margin %d minutes\n", units);
0162     }
0163     superio_outb(config, WDT_CONFIG);
0164
0165     if (revision >= 0x08)
0166         superio_outb(units >> 8, WDT_TIMEOUT + 1);
0167     superio_outb(units, WDT_TIMEOUT);
0168 }
0169
0170 static int it8712f_wdt_get_status(void)
0171 {
0172     if (superio_inb(WDT_CONTROL) & 0x01)
0173         return WDIOF_CARDRESET;
0174     else
0175         return 0;
0176 }
0177
0178 static int it8712f_wdt_enable(void)
0179 {
0180     int ret = superio_enter();
0181     if (ret)
0182         return ret;
0183
0184     pr_debug("enabling watchdog timer\n");
0185     superio_select(LDN_GPIO);
0186
0187     superio_outb(wdt_control_reg, WDT_CONTROL);
0188
0189     it8712f_wdt_update_margin();
0190
0191     superio_exit();
0192
0193     it8712f_wdt_ping();
0194
0195     return 0;
0196 }
0197
0198 static int it8712f_wdt_disable(void)
0199 {
0200     int ret = superio_enter();
0201     if (ret)
0202         return ret;
0203
0204     pr_debug("disabling watchdog timer\n");
0205     superio_select(LDN_GPIO);
0206
0207     superio_outb(0, WDT_CONFIG);
0208     superio_outb(0, WDT_CONTROL);
0209     if (revision >= 0x08)
0210         superio_outb(0, WDT_TIMEOUT + 1);
0211     superio_outb(0, WDT_TIMEOUT);
0212
0213     superio_exit();
0214     return 0;
0215 }
0216
0217 static int it8712f_wdt_notify(struct notifier_block *this,
0218             unsigned long code, void *unused)
0219 {
0220     if (code == SYS_HALT || code == SYS_POWER_OFF)
0221         if (!nowayout)
0222             it8712f_wdt_disable();
0223
0224     return NOTIFY_DONE;
0225 }
0226
0227 static struct notifier_block it8712f_wdt_notifier = {
0228     .notifier_call = it8712f_wdt_notify,
0229 };
0230
0231 static ssize_t it8712f_wdt_write(struct file *file, const char __user *data,
0232                     size_t len, loff_t *ppos)
0233 {
0234     /* check for a magic close character */
0235     if (len) {
0236         size_t i;
0237
0238         it8712f_wdt_ping();
0239
0240         expect_close = 0;
0241         for (i = 0; i < len; ++i) {
0242             char c;
0243             if (get_user(c, data + i))
0244                 return -EFAULT;
0245             if (c == 'V')
0246                 expect_close = 42;
0247         }
0248     }
0249
0250     return len;
0251 }
0252
0253 static long it8712f_wdt_ioctl(struct file *file, unsigned int cmd,
0254                             unsigned long arg)
0255 {
0256     void __user *argp = (void __user *)arg;
0257     int __user *p = argp;
0258     static const struct watchdog_info ident = {
0259         .identity = "IT8712F Watchdog",
0260         .firmware_version = 1,
0261         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
0262                         WDIOF_MAGICCLOSE,
0263     };
0264     int value;
0265     int ret;
0266
0267     switch (cmd) {
0268     case WDIOC_GETSUPPORT:
0269         if (copy_to_user(argp, &ident, sizeof(ident)))
0270             return -EFAULT;
0271         return 0;
0272     case WDIOC_GETSTATUS:
0273         ret = superio_enter();
0274         if (ret)
0275             return ret;
0276         superio_select(LDN_GPIO);
0277
0278         value = it8712f_wdt_get_status();
0279
0280         superio_exit();
0281
0282         return put_user(value, p);
0283     case WDIOC_GETBOOTSTATUS:
0284         return put_user(0, p);
0285     case WDIOC_KEEPALIVE:
0286         it8712f_wdt_ping();
0287         return 0;
0288     case WDIOC_SETTIMEOUT:
0289         if (get_user(value, p))
0290             return -EFAULT;
0291         if (value < 1)
0292             return -EINVAL;
0293         if (value > (max_units * 60))
0294             return -EINVAL;
0295         margin = value;
0296         ret = superio_enter();
0297         if (ret)
0298             return ret;
0299         superio_select(LDN_GPIO);
0300
0301         it8712f_wdt_update_margin();
0302
0303         superio_exit();
0304         it8712f_wdt_ping();
0305         fallthrough;
0306     case WDIOC_GETTIMEOUT:
0307         if (put_user(margin, p))
0308             return -EFAULT;
0309         return 0;
0310     default:
0311         return -ENOTTY;
0312     }
0313 }
0314
0315 static int it8712f_wdt_open(struct inode *inode, struct file *file)
0316 {
0317     int ret;
0318     /* only allow one at a time */
0319     if (test_and_set_bit(0, &wdt_open))
0320         return -EBUSY;
0321
0322     ret = it8712f_wdt_enable();
0323     if (ret)
0324         return ret;
0325     return stream_open(inode, file);
0326 }
0327
0328 static int it8712f_wdt_release(struct inode *inode, struct file *file)
0329 {
0330     if (expect_close != 42) {
0331         pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
0332     } else if (!nowayout) {
0333         if (it8712f_wdt_disable())
0334             pr_warn("Watchdog disable failed\n");
0335     }
0336     expect_close = 0;
0337     clear_bit(0, &wdt_open);
0338
0339     return 0;
0340 }
0341
0342 static const struct file_operations it8712f_wdt_fops = {
0343     .owner = THIS_MODULE,
0344     .llseek = no_llseek,
0345     .write = it8712f_wdt_write,
0346     .unlocked_ioctl = it8712f_wdt_ioctl,
0347     .compat_ioctl = compat_ptr_ioctl,
0348     .open = it8712f_wdt_open,
0349     .release = it8712f_wdt_release,
0350 };
0351
0352 static struct miscdevice it8712f_wdt_miscdev = {
0353     .minor = WATCHDOG_MINOR,
0354     .name = "watchdog",
0355     .fops = &it8712f_wdt_fops,
0356 };
0357
0358 static int __init it8712f_wdt_find(unsigned short *address)
0359 {
0360     int err = -ENODEV;
0361     int chip_type;
0362     int ret = superio_enter();
0363     if (ret)
0364         return ret;
0365
0366     chip_type = superio_inw(DEVID);
0367     if (chip_type != IT8712F_DEVID)
0368         goto exit;
0369
0370     superio_select(LDN_GAME);
0371     superio_outb(1, ACT_REG);
0372     if (!(superio_inb(ACT_REG) & 0x01)) {
0373         pr_err("Device not activated, skipping\n");
0374         goto exit;
0375     }
0376
0377     *address = superio_inw(BASE_REG);
0378     if (*address == 0) {
0379         pr_err("Base address not set, skipping\n");
0380         goto exit;
0381     }
0382
0383     err = 0;
0384     revision = superio_inb(DEVREV) & 0x0f;
0385
0386     /* Later revisions have 16-bit values per datasheet 0.9.1 */
0387     if (revision >= 0x08)
0388         max_units = 65535;
0389
0390     if (margin > (max_units * 60))
0391         margin = (max_units * 60);
0392
0393     pr_info("Found IT%04xF chip revision %d - using DogFood address 0x%x\n",
0394         chip_type, revision, *address);
0395
0396 exit:
0397     superio_exit();
0398     return err;
0399 }
0400
0401 static int __init it8712f_wdt_init(void)
0402 {
0403     int err = 0;
0404
0405     if (it8712f_wdt_find(&address))
0406         return -ENODEV;
0407
0408     if (!request_region(address, 1, "IT8712F Watchdog")) {
0409         pr_warn("watchdog I/O region busy\n");
0410         return -EBUSY;
0411     }
0412
0413     err = it8712f_wdt_disable();
0414     if (err) {
0415         pr_err("unable to disable watchdog timer\n");
0416         goto out;
0417     }
0418
0419     err = register_reboot_notifier(&it8712f_wdt_notifier);
0420     if (err) {
0421         pr_err("unable to register reboot notifier\n");
0422         goto out;
0423     }
0424
0425     err = misc_register(&it8712f_wdt_miscdev);
0426     if (err) {
0427         pr_err("cannot register miscdev on minor=%d (err=%d)\n",
0428                WATCHDOG_MINOR, err);
0429         goto reboot_out;
0430     }
0431
0432     return 0;
0433
0434
0435 reboot_out:
0436     unregister_reboot_notifier(&it8712f_wdt_notifier);
0437 out:
0438     release_region(address, 1);
0439     return err;
0440 }
0441
0442 static void __exit it8712f_wdt_exit(void)
0443 {
0444     misc_deregister(&it8712f_wdt_miscdev);
0445     unregister_reboot_notifier(&it8712f_wdt_notifier);
0446     release_region(address, 1);
0447 }
0448
0449 module_init(it8712f_wdt_init);
0450 module_exit(it8712f_wdt_exit);