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 NAME "it8712f_wdt"
  35
  36 MODULE_AUTHOR("Jorge Boncompte - DTI2 <jorge@dti2.net>");
  37 MODULE_DESCRIPTION("IT8712F Watchdog Driver");
  38 MODULE_LICENSE("GPL");
  39
  40 static int max_units = 255;
  41 static int margin = 60;         /* in seconds */
  42 module_param(margin, int, 0);
  43 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
  44
  45 static bool nowayout = WATCHDOG_NOWAYOUT;
  46 module_param(nowayout, bool, 0);
  47 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
  48
  49 static unsigned long wdt_open;
  50 static unsigned expect_close;
  51 static unsigned char revision;
  52
  53 /* Dog Food address - We use the game port address */
  54 static 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
  84 static int wdt_control_reg = WDT_RESET_GAME;
  85 module_param(wdt_control_reg, int, 0);
  86 MODULE_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
  92 static int superio_inb(int reg)
  93 {
  94         outb(reg, REG);
  95         return inb(VAL);
  96 }
  97
  98 static void superio_outb(int val, int reg)
  99 {
 100         outb(reg, REG);
 101         outb(val, VAL);
 102 }
 103
 104 static int superio_inw(int reg)
 105 {
 106         int val;
 107         outb(reg++, REG);
 108         val = inb(VAL) << 8;
 109         outb(reg, REG);
 110         val |= inb(VAL);
 111         return val;
 112 }
 113
 114 static inline void superio_select(int ldn)
 115 {
 116         outb(LDN, REG);
 117         outb(ldn, VAL);
 118 }
 119
 120 static 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(0x87, REG);
 129         outb(0x01, REG);
 130         outb(0x55, REG);
 131         outb(0x55, REG);
 132         return 0;
 133 }
 134
 135 static inline void superio_exit(void)
 136 {
 137         outb(0x02, REG);
 138         outb(0x02, VAL);
 139         release_region(REG, 2);
 140 }
 141
 142 static inline void it8712f_wdt_ping(void)
 143 {
 144         if (wdt_control_reg & WDT_RESET_GAME)
 145                 inb(address);
 146 }
 147
 148 static 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(config, WDT_CONFIG);
 164
 165         if (revision >= 0x08)
 166                 superio_outb(units >> 8, WDT_TIMEOUT + 1);
 167         superio_outb(units, WDT_TIMEOUT);
 168 }
 169
 170 static 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
 178 static 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(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
 198 static 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(0, WDT_CONFIG);
 208         superio_outb(0, WDT_CONTROL);
 209         if (revision >= 0x08)
 210                 superio_outb(0, WDT_TIMEOUT + 1);
 211         superio_outb(0, WDT_TIMEOUT);
 212
 213         superio_exit();
 214         return 0;
 215 }
 216
 217 static 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
 227 static struct notifier_block it8712f_wdt_notifier = {
 228         .notifier_call = it8712f_wdt_notify,
 229 };
 230
 231 static 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
 253 static 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(argp, &ident, 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
 315 static 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(0, &wdt_open))
 320                 return -EBUSY;
 321
 322         ret = it8712f_wdt_enable();
 323         if (ret)
 324                 return ret;
 325         return stream_open(inode, file);
 326 }
 327
 328 static 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(0, &wdt_open);
 338
 339         return 0;
 340 }
 341
 342 static 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
 351 static struct miscdevice it8712f_wdt_miscdev = {
 352         .minor = WATCHDOG_MINOR,
 353         .name = "watchdog",
 354         .fops = &it8712f_wdt_fops,
 355 };
 356
 357 static 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(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
 395 exit:
 396         superio_exit();
 397         return err;
 398 }
 399
 400 static int __init it8712f_wdt_init(void)
 401 {
 402         int err = 0;
 403
 404         if (it8712f_wdt_find(&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(&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
 434 reboot_out:
 435         unregister_reboot_notifier(&it8712f_wdt_notifier);
 436 out:
 437         release_region(address, 1);
 438         return err;
 439 }
 440
 441 static void __exit it8712f_wdt_exit(void)
 442 {
 443         misc_deregister(&it8712f_wdt_miscdev);
 444         unregister_reboot_notifier(&it8712f_wdt_notifier);
 445         release_region(address, 1);
 446 }
 447
 448 module_init(it8712f_wdt_init);
 449 module_exit(it8712f_wdt_exit);