drivers/watchdog/it8712f_wdt.c

   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 DEBUG
  35 #define NAME "it8712f_wdt"
  36
  37 MODULE_AUTHOR("Jorge Boncompte - DTI2 <jorge@dti2.net>");
  38 MODULE_DESCRIPTION("IT8712F Watchdog Driver");
  39 MODULE_LICENSE("GPL");
  40
  41 static int max_units = 255;
  42 static int margin = 60;         /* in seconds */
  43 module_param(margin, int, 0);
  44 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
  45
  46 static bool nowayout = WATCHDOG_NOWAYOUT;
  47 module_param(nowayout, bool, 0);
  48 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
  49
  50 static unsigned long wdt_open;
  51 static unsigned expect_close;
  52 static unsigned char revision;
  53
  54 /* Dog Food address - We use the game port address */
  55 static unsigned short address;
  56
  57 #define REG             0x2e    /* The register to read/write */
  58 #define VAL             0x2f    /* The value to read/write */
  59
  60 #define LDN             0x07    /* Register: Logical device select */
  61 #define DEVID           0x20    /* Register: Device ID */
  62 #define DEVREV          0x22    /* Register: Device Revision */
  63 #define ACT_REG         0x30    /* LDN Register: Activation */
  64 #define BASE_REG        0x60    /* LDN Register: Base address */
  65
  66 #define IT8712F_DEVID   0x8712
  67
  68 #define LDN_GPIO        0x07    /* GPIO and Watch Dog Timer */
  69 #define LDN_GAME        0x09    /* Game Port */
  70
  71 #define WDT_CONTROL     0x71    /* WDT Register: Control */
  72 #define WDT_CONFIG      0x72    /* WDT Register: Configuration */
  73 #define WDT_TIMEOUT     0x73    /* WDT Register: Timeout Value */
  74
  75 #define WDT_RESET_GAME  0x10    /* Reset timer on read or write to game port */
  76 #define WDT_RESET_KBD   0x20    /* Reset timer on keyboard interrupt */
  77 #define WDT_RESET_MOUSE 0x40    /* Reset timer on mouse interrupt */
  78 #define WDT_RESET_CIR   0x80    /* Reset timer on consumer IR interrupt */
  79
  80 #define WDT_UNIT_SEC    0x80    /* If 0 in MINUTES */
  81
  82 #define WDT_OUT_PWROK   0x10    /* Pulse PWROK on timeout */
  83 #define WDT_OUT_KRST    0x40    /* Pulse reset on timeout */
  84
  85 static int wdt_control_reg = WDT_RESET_GAME;
  86 module_param(wdt_control_reg, int, 0);
  87 MODULE_PARM_DESC(wdt_control_reg, "Value to write to watchdog control "
  88                 "register. The default WDT_RESET_GAME resets the timer on "
  89                 "game port reads that this driver generates. You can also "
  90                 "use KBD, MOUSE or CIR if you have some external way to "
  91                 "generate those interrupts.");
  92
  93 static int superio_inb(int reg)
  94 {
  95         outb(reg, REG);
  96         return inb(VAL);
  97 }
  98
  99 static void superio_outb(int val, int reg)
 100 {
 101         outb(reg, REG);
 102         outb(val, VAL);
 103 }
 104
 105 static int superio_inw(int reg)
 106 {
 107         int val;
 108         outb(reg++, REG);
 109         val = inb(VAL) << 8;
 110         outb(reg, REG);
 111         val |= inb(VAL);
 112         return val;
 113 }
 114
 115 static inline void superio_select(int ldn)
 116 {
 117         outb(LDN, REG);
 118         outb(ldn, VAL);
 119 }
 120
 121 static inline int superio_enter(void)
 122 {
 123         /*
 124          * Try to reserve REG and REG + 1 for exclusive access.
 125          */
 126         if (!request_muxed_region(REG, 2, NAME))
 127                 return -EBUSY;
 128
 129         outb(0x87, REG);
 130         outb(0x01, REG);
 131         outb(0x55, REG);
 132         outb(0x55, REG);
 133         return 0;
 134 }
 135
 136 static inline void superio_exit(void)
 137 {
 138         outb(0x02, REG);
 139         outb(0x02, VAL);
 140         release_region(REG, 2);
 141 }
 142
 143 static inline void it8712f_wdt_ping(void)
 144 {
 145         if (wdt_control_reg & WDT_RESET_GAME)
 146                 inb(address);
 147 }
 148
 149 static void it8712f_wdt_update_margin(void)
 150 {
 151         int config = WDT_OUT_KRST | WDT_OUT_PWROK;
 152         int units = margin;
 153
 154         /* Switch to minutes precision if the configured margin
 155          * value does not fit within the register width.
 156          */
 157         if (units <= max_units) {
 158                 config |= WDT_UNIT_SEC; /* else UNIT is MINUTES */
 159                 pr_info("timer margin %d seconds\n", units);
 160         } else {
 161                 units /= 60;
 162                 pr_info("timer margin %d minutes\n", units);
 163         }
 164         superio_outb(config, WDT_CONFIG);
 165
 166         if (revision >= 0x08)
 167                 superio_outb(units >> 8, WDT_TIMEOUT + 1);
 168         superio_outb(units, WDT_TIMEOUT);
 169 }
 170
 171 static int it8712f_wdt_get_status(void)
 172 {
 173         if (superio_inb(WDT_CONTROL) & 0x01)
 174                 return WDIOF_CARDRESET;
 175         else
 176                 return 0;
 177 }
 178
 179 static int it8712f_wdt_enable(void)
 180 {
 181         int ret = superio_enter();
 182         if (ret)
 183                 return ret;
 184
 185         pr_debug("enabling watchdog timer\n");
 186         superio_select(LDN_GPIO);
 187
 188         superio_outb(wdt_control_reg, WDT_CONTROL);
 189
 190         it8712f_wdt_update_margin();
 191
 192         superio_exit();
 193
 194         it8712f_wdt_ping();
 195
 196         return 0;
 197 }
 198
 199 static int it8712f_wdt_disable(void)
 200 {
 201         int ret = superio_enter();
 202         if (ret)
 203                 return ret;
 204
 205         pr_debug("disabling watchdog timer\n");
 206         superio_select(LDN_GPIO);
 207
 208         superio_outb(0, WDT_CONFIG);
 209         superio_outb(0, WDT_CONTROL);
 210         if (revision >= 0x08)
 211                 superio_outb(0, WDT_TIMEOUT + 1);
 212         superio_outb(0, WDT_TIMEOUT);
 213
 214         superio_exit();
 215         return 0;
 216 }
 217
 218 static int it8712f_wdt_notify(struct notifier_block *this,
 219                     unsigned long code, void *unused)
 220 {
 221         if (code == SYS_HALT || code == SYS_POWER_OFF)
 222                 if (!nowayout)
 223                         it8712f_wdt_disable();
 224
 225         return NOTIFY_DONE;
 226 }
 227
 228 static struct notifier_block it8712f_wdt_notifier = {
 229         .notifier_call = it8712f_wdt_notify,
 230 };
 231
 232 static ssize_t it8712f_wdt_write(struct file *file, const char __user *data,
 233                                         size_t len, loff_t *ppos)
 234 {
 235         /* check for a magic close character */
 236         if (len) {
 237                 size_t i;
 238
 239                 it8712f_wdt_ping();
 240
 241                 expect_close = 0;
 242                 for (i = 0; i < len; ++i) {
 243                         char c;
 244                         if (get_user(c, data + i))
 245                                 return -EFAULT;
 246                         if (c == 'V')
 247                                 expect_close = 42;
 248                 }
 249         }
 250
 251         return len;
 252 }
 253
 254 static long it8712f_wdt_ioctl(struct file *file, unsigned int cmd,
 255                                                         unsigned long arg)
 256 {
 257         void __user *argp = (void __user *)arg;
 258         int __user *p = argp;
 259         static const struct watchdog_info ident = {
 260                 .identity = "IT8712F Watchdog",
 261                 .firmware_version = 1,
 262                 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 263                                                 WDIOF_MAGICCLOSE,
 264         };
 265         int value;
 266         int ret;
 267
 268         switch (cmd) {
 269         case WDIOC_GETSUPPORT:
 270                 if (copy_to_user(argp, &ident, sizeof(ident)))
 271                         return -EFAULT;
 272                 return 0;
 273         case WDIOC_GETSTATUS:
 274                 ret = superio_enter();
 275                 if (ret)
 276                         return ret;
 277                 superio_select(LDN_GPIO);
 278
 279                 value = it8712f_wdt_get_status();
 280
 281                 superio_exit();
 282
 283                 return put_user(value, p);
 284         case WDIOC_GETBOOTSTATUS:
 285                 return put_user(0, p);
 286         case WDIOC_KEEPALIVE:
 287                 it8712f_wdt_ping();
 288                 return 0;
 289         case WDIOC_SETTIMEOUT:
 290                 if (get_user(value, p))
 291                         return -EFAULT;
 292                 if (value < 1)
 293                         return -EINVAL;
 294                 if (value > (max_units * 60))
 295                         return -EINVAL;
 296                 margin = value;
 297                 ret = superio_enter();
 298                 if (ret)
 299                         return ret;
 300                 superio_select(LDN_GPIO);
 301
 302                 it8712f_wdt_update_margin();
 303
 304                 superio_exit();
 305                 it8712f_wdt_ping();
 306                 fallthrough;
 307         case WDIOC_GETTIMEOUT:
 308                 if (put_user(margin, p))
 309                         return -EFAULT;
 310                 return 0;
 311         default:
 312                 return -ENOTTY;
 313         }
 314 }
 315
 316 static int it8712f_wdt_open(struct inode *inode, struct file *file)
 317 {
 318         int ret;
 319         /* only allow one at a time */
 320         if (test_and_set_bit(0, &wdt_open))
 321                 return -EBUSY;
 322
 323         ret = it8712f_wdt_enable();
 324         if (ret)
 325                 return ret;
 326         return stream_open(inode, file);
 327 }
 328
 329 static int it8712f_wdt_release(struct inode *inode, struct file *file)
 330 {
 331         if (expect_close != 42) {
 332                 pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
 333         } else if (!nowayout) {
 334                 if (it8712f_wdt_disable())
 335                         pr_warn("Watchdog disable failed\n");
 336         }
 337         expect_close = 0;
 338         clear_bit(0, &wdt_open);
 339
 340         return 0;
 341 }
 342
 343 static const struct file_operations it8712f_wdt_fops = {
 344         .owner = THIS_MODULE,
 345         .llseek = no_llseek,
 346         .write = it8712f_wdt_write,
 347         .unlocked_ioctl = it8712f_wdt_ioctl,
 348         .compat_ioctl = compat_ptr_ioctl,
 349         .open = it8712f_wdt_open,
 350         .release = it8712f_wdt_release,
 351 };
 352
 353 static struct miscdevice it8712f_wdt_miscdev = {
 354         .minor = WATCHDOG_MINOR,
 355         .name = "watchdog",
 356         .fops = &it8712f_wdt_fops,
 357 };
 358
 359 static int __init it8712f_wdt_find(unsigned short *address)
 360 {
 361         int err = -ENODEV;
 362         int chip_type;
 363         int ret = superio_enter();
 364         if (ret)
 365                 return ret;
 366
 367         chip_type = superio_inw(DEVID);
 368         if (chip_type != IT8712F_DEVID)
 369                 goto exit;
 370
 371         superio_select(LDN_GAME);
 372         superio_outb(1, ACT_REG);
 373         if (!(superio_inb(ACT_REG) & 0x01)) {
 374                 pr_err("Device not activated, skipping\n");
 375                 goto exit;
 376         }
 377
 378         *address = superio_inw(BASE_REG);
 379         if (*address == 0) {
 380                 pr_err("Base address not set, skipping\n");
 381                 goto exit;
 382         }
 383
 384         err = 0;
 385         revision = superio_inb(DEVREV) & 0x0f;
 386
 387         /* Later revisions have 16-bit values per datasheet 0.9.1 */
 388         if (revision >= 0x08)
 389                 max_units = 65535;
 390
 391         if (margin > (max_units * 60))
 392                 margin = (max_units * 60);
 393
 394         pr_info("Found IT%04xF chip revision %d - using DogFood address 0x%x\n",
 395                 chip_type, revision, *address);
 396
 397 exit:
 398         superio_exit();
 399         return err;
 400 }
 401
 402 static int __init it8712f_wdt_init(void)
 403 {
 404         int err = 0;
 405
 406         if (it8712f_wdt_find(&address))
 407                 return -ENODEV;
 408
 409         if (!request_region(address, 1, "IT8712F Watchdog")) {
 410                 pr_warn("watchdog I/O region busy\n");
 411                 return -EBUSY;
 412         }
 413
 414         err = it8712f_wdt_disable();
 415         if (err) {
 416                 pr_err("unable to disable watchdog timer\n");
 417                 goto out;
 418         }
 419
 420         err = register_reboot_notifier(&it8712f_wdt_notifier);
 421         if (err) {
 422                 pr_err("unable to register reboot notifier\n");
 423                 goto out;
 424         }
 425
 426         err = misc_register(&it8712f_wdt_miscdev);
 427         if (err) {
 428                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 429                        WATCHDOG_MINOR, err);
 430                 goto reboot_out;
 431         }
 432
 433         return 0;
 434
 435
 436 reboot_out:
 437         unregister_reboot_notifier(&it8712f_wdt_notifier);
 438 out:
 439         release_region(address, 1);
 440         return err;
 441 }
 442
 443 static void __exit it8712f_wdt_exit(void)
 444 {
 445         misc_deregister(&it8712f_wdt_miscdev);
 446         unregister_reboot_notifier(&it8712f_wdt_notifier);
 447         release_region(address, 1);
 448 }
 449
 450 module_init(it8712f_wdt_init);
 451 module_exit(it8712f_wdt_exit);