drivers/watchdog/sbc8360.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *      SBC8360 Watchdog driver
   4  *
   5  *      (c) Copyright 2005 Webcon, Inc.
   6  *
   7  *      Based on ib700wdt.c, which is based on advantechwdt.c which is based
   8  *      on acquirewdt.c which is based on wdt.c.
   9  *
  10  *      (c) Copyright 2001 Charles Howes <chowes@vsol.net>
  11  *
  12  *      Based on advantechwdt.c which is based on acquirewdt.c which
  13  *      is based on wdt.c.
  14  *
  15  *      (c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
  16  *
  17  *      Based on acquirewdt.c which is based on wdt.c.
  18  *      Original copyright messages:
  19  *
  20  *      (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
  21  *                                              All Rights Reserved.
  22  *
  23  *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  24  *      warranty for any of this software. This material is provided
  25  *      "AS-IS" and at no charge.
  26  *
  27  *      (c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
  28  *
  29  *      14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
  30  *           Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
  31  *           Added timeout module option to override default
  32  *
  33  */
  34
  35 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  36
  37 #include <linux/module.h>
  38 #include <linux/types.h>
  39 #include <linux/miscdevice.h>
  40 #include <linux/watchdog.h>
  41 #include <linux/ioport.h>
  42 #include <linux/delay.h>
  43 #include <linux/notifier.h>
  44 #include <linux/fs.h>
  45 #include <linux/reboot.h>
  46 #include <linux/init.h>
  47 #include <linux/spinlock.h>
  48 #include <linux/moduleparam.h>
  49 #include <linux/io.h>
  50 #include <linux/uaccess.h>
  51
  52
  53 static unsigned long sbc8360_is_open;
  54 static char expect_close;
  55
  56 /*
  57  *
  58  * Watchdog Timer Configuration
  59  *
  60  * The function of the watchdog timer is to reset the system automatically
  61  * and is defined at I/O port 0120H and 0121H.  To enable the watchdog timer
  62  * and allow the system to reset, write appropriate values from the table
  63  * below to I/O port 0120H and 0121H.  To disable the timer, write a zero
  64  * value to I/O port 0121H for the system to stop the watchdog function.
  65  *
  66  * The following describes how the timer should be programmed (according to
  67  * the vendor documentation)
  68  *
  69  * Enabling Watchdog:
  70  * MOV AX,000AH (enable, phase I)
  71  * MOV DX,0120H
  72  * OUT DX,AX
  73  * MOV AX,000BH (enable, phase II)
  74  * MOV DX,0120H
  75  * OUT DX,AX
  76  * MOV AX,000nH (set multiplier n, from 1-4)
  77  * MOV DX,0120H
  78  * OUT DX,AX
  79  * MOV AX,000mH (set base timer m, from 0-F)
  80  * MOV DX,0121H
  81  * OUT DX,AX
  82  *
  83  * Reset timer:
  84  * MOV AX,000mH (same as set base timer, above)
  85  * MOV DX,0121H
  86  * OUT DX,AX
  87  *
  88  * Disabling Watchdog:
  89  * MOV AX,0000H (a zero value)
  90  * MOV DX,0120H
  91  * OUT DX,AX
  92  *
  93  * Watchdog timeout configuration values:
  94  *              N
  95  *      M |     1       2       3       4
  96  *      --|----------------------------------
  97  *      0 |     0.5s    5s      50s     100s
  98  *      1 |     1s      10s     100s    200s
  99  *      2 |     1.5s    15s     150s    300s
 100  *      3 |     2s      20s     200s    400s
 101  *      4 |     2.5s    25s     250s    500s
 102  *      5 |     3s      30s     300s    600s
 103  *      6 |     3.5s    35s     350s    700s
 104  *      7 |     4s      40s     400s    800s
 105  *      8 |     4.5s    45s     450s    900s
 106  *      9 |     5s      50s     500s    1000s
 107  *      A |     5.5s    55s     550s    1100s
 108  *      B |     6s      60s     600s    1200s
 109  *      C |     6.5s    65s     650s    1300s
 110  *      D |     7s      70s     700s    1400s
 111  *      E |     7.5s    75s     750s    1500s
 112  *      F |     8s      80s     800s    1600s
 113  *
 114  * Another way to say the same things is:
 115  *  For N=1, Timeout = (M+1) * 0.5s
 116  *  For N=2, Timeout = (M+1) * 5s
 117  *  For N=3, Timeout = (M+1) * 50s
 118  *  For N=4, Timeout = (M+1) * 100s
 119  *
 120  */
 121
 122 static int wd_times[64][2] = {
 123         {0, 1},                 /* 0  = 0.5s */
 124         {1, 1},                 /* 1  = 1s   */
 125         {2, 1},                 /* 2  = 1.5s */
 126         {3, 1},                 /* 3  = 2s   */
 127         {4, 1},                 /* 4  = 2.5s */
 128         {5, 1},                 /* 5  = 3s   */
 129         {6, 1},                 /* 6  = 3.5s */
 130         {7, 1},                 /* 7  = 4s   */
 131         {8, 1},                 /* 8  = 4.5s */
 132         {9, 1},                 /* 9  = 5s   */
 133         {0xA, 1},               /* 10 = 5.5s */
 134         {0xB, 1},               /* 11 = 6s   */
 135         {0xC, 1},               /* 12 = 6.5s */
 136         {0xD, 1},               /* 13 = 7s   */
 137         {0xE, 1},               /* 14 = 7.5s */
 138         {0xF, 1},               /* 15 = 8s   */
 139         {0, 2},                 /* 16 = 5s  */
 140         {1, 2},                 /* 17 = 10s */
 141         {2, 2},                 /* 18 = 15s */
 142         {3, 2},                 /* 19 = 20s */
 143         {4, 2},                 /* 20 = 25s */
 144         {5, 2},                 /* 21 = 30s */
 145         {6, 2},                 /* 22 = 35s */
 146         {7, 2},                 /* 23 = 40s */
 147         {8, 2},                 /* 24 = 45s */
 148         {9, 2},                 /* 25 = 50s */
 149         {0xA, 2},               /* 26 = 55s */
 150         {0xB, 2},               /* 27 = 60s */
 151         {0xC, 2},               /* 28 = 65s */
 152         {0xD, 2},               /* 29 = 70s */
 153         {0xE, 2},               /* 30 = 75s */
 154         {0xF, 2},               /* 31 = 80s */
 155         {0, 3},                 /* 32 = 50s  */
 156         {1, 3},                 /* 33 = 100s */
 157         {2, 3},                 /* 34 = 150s */
 158         {3, 3},                 /* 35 = 200s */
 159         {4, 3},                 /* 36 = 250s */
 160         {5, 3},                 /* 37 = 300s */
 161         {6, 3},                 /* 38 = 350s */
 162         {7, 3},                 /* 39 = 400s */
 163         {8, 3},                 /* 40 = 450s */
 164         {9, 3},                 /* 41 = 500s */
 165         {0xA, 3},               /* 42 = 550s */
 166         {0xB, 3},               /* 43 = 600s */
 167         {0xC, 3},               /* 44 = 650s */
 168         {0xD, 3},               /* 45 = 700s */
 169         {0xE, 3},               /* 46 = 750s */
 170         {0xF, 3},               /* 47 = 800s */
 171         {0, 4},                 /* 48 = 100s */
 172         {1, 4},                 /* 49 = 200s */
 173         {2, 4},                 /* 50 = 300s */
 174         {3, 4},                 /* 51 = 400s */
 175         {4, 4},                 /* 52 = 500s */
 176         {5, 4},                 /* 53 = 600s */
 177         {6, 4},                 /* 54 = 700s */
 178         {7, 4},                 /* 55 = 800s */
 179         {8, 4},                 /* 56 = 900s */
 180         {9, 4},                 /* 57 = 1000s */
 181         {0xA, 4},               /* 58 = 1100s */
 182         {0xB, 4},               /* 59 = 1200s */
 183         {0xC, 4},               /* 60 = 1300s */
 184         {0xD, 4},               /* 61 = 1400s */
 185         {0xE, 4},               /* 62 = 1500s */
 186         {0xF, 4}                /* 63 = 1600s */
 187 };
 188
 189 #define SBC8360_ENABLE 0x120
 190 #define SBC8360_BASETIME 0x121
 191
 192 static int timeout = 27;
 193 static int wd_margin = 0xB;
 194 static int wd_multiplier = 2;
 195 static bool nowayout = WATCHDOG_NOWAYOUT;
 196
 197 module_param(timeout, int, 0);
 198 MODULE_PARM_DESC(timeout, "Index into timeout table (0-63) (default=27 (60s))");
 199 module_param(nowayout, bool, 0);
 200 MODULE_PARM_DESC(nowayout,
 201                  "Watchdog cannot be stopped once started (default="
 202                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 203
 204 /*
 205  *      Kernel methods.
 206  */
 207
 208 /* Activate and pre-configure watchdog */
 209 static void sbc8360_activate(void)
 210 {
 211         /* Enable the watchdog */
 212         outb(0x0A, SBC8360_ENABLE);
 213         msleep_interruptible(100);
 214         outb(0x0B, SBC8360_ENABLE);
 215         msleep_interruptible(100);
 216         /* Set timeout multiplier */
 217         outb(wd_multiplier, SBC8360_ENABLE);
 218         msleep_interruptible(100);
 219         /* Nothing happens until first sbc8360_ping() */
 220 }
 221
 222 /* Kernel pings watchdog */
 223 static void sbc8360_ping(void)
 224 {
 225         /* Write the base timer register */
 226         outb(wd_margin, SBC8360_BASETIME);
 227 }
 228
 229 /* stop watchdog */
 230 static void sbc8360_stop(void)
 231 {
 232         /* De-activate the watchdog */
 233         outb(0, SBC8360_ENABLE);
 234 }
 235
 236 /* Userspace pings kernel driver, or requests clean close */
 237 static ssize_t sbc8360_write(struct file *file, const char __user *buf,
 238                              size_t count, loff_t *ppos)
 239 {
 240         if (count) {
 241                 if (!nowayout) {
 242                         size_t i;
 243
 244                         /* In case it was set long ago */
 245                         expect_close = 0;
 246
 247                         for (i = 0; i != count; i++) {
 248                                 char c;
 249                                 if (get_user(c, buf + i))
 250                                         return -EFAULT;
 251                                 if (c == 'V')
 252                                         expect_close = 42;
 253                         }
 254                 }
 255                 sbc8360_ping();
 256         }
 257         return count;
 258 }
 259
 260 static int sbc8360_open(struct inode *inode, struct file *file)
 261 {
 262         if (test_and_set_bit(0, &sbc8360_is_open))
 263                 return -EBUSY;
 264         if (nowayout)
 265                 __module_get(THIS_MODULE);
 266
 267         /* Activate and ping once to start the countdown */
 268         sbc8360_activate();
 269         sbc8360_ping();
 270         return stream_open(inode, file);
 271 }
 272
 273 static int sbc8360_close(struct inode *inode, struct file *file)
 274 {
 275         if (expect_close == 42)
 276                 sbc8360_stop();
 277         else
 278                 pr_crit("SBC8360 device closed unexpectedly.  SBC8360 will not stop!\n");
 279
 280         clear_bit(0, &sbc8360_is_open);
 281         expect_close = 0;
 282         return 0;
 283 }
 284
 285 /*
 286  *      Notifier for system down
 287  */
 288
 289 static int sbc8360_notify_sys(struct notifier_block *this, unsigned long code,
 290                               void *unused)
 291 {
 292         if (code == SYS_DOWN || code == SYS_HALT)
 293                 sbc8360_stop(); /* Disable the SBC8360 Watchdog */
 294
 295         return NOTIFY_DONE;
 296 }
 297
 298 /*
 299  *      Kernel Interfaces
 300  */
 301
 302 static const struct file_operations sbc8360_fops = {
 303         .owner = THIS_MODULE,
 304         .llseek = no_llseek,
 305         .write = sbc8360_write,
 306         .open = sbc8360_open,
 307         .release = sbc8360_close,
 308 };
 309
 310 static struct miscdevice sbc8360_miscdev = {
 311         .minor = WATCHDOG_MINOR,
 312         .name = "watchdog",
 313         .fops = &sbc8360_fops,
 314 };
 315
 316 /*
 317  *      The SBC8360 needs to learn about soft shutdowns in order to
 318  *      turn the timebomb registers off.
 319  */
 320
 321 static struct notifier_block sbc8360_notifier = {
 322         .notifier_call = sbc8360_notify_sys,
 323 };
 324
 325 static int __init sbc8360_init(void)
 326 {
 327         int res;
 328         unsigned long int mseconds = 60000;
 329
 330         if (timeout < 0 || timeout > 63) {
 331                 pr_err("Invalid timeout index (must be 0-63)\n");
 332                 res = -EINVAL;
 333                 goto out;
 334         }
 335
 336         if (!request_region(SBC8360_ENABLE, 1, "SBC8360")) {
 337                 pr_err("ENABLE method I/O %X is not available\n",
 338                        SBC8360_ENABLE);
 339                 res = -EIO;
 340                 goto out;
 341         }
 342         if (!request_region(SBC8360_BASETIME, 1, "SBC8360")) {
 343                 pr_err("BASETIME method I/O %X is not available\n",
 344                        SBC8360_BASETIME);
 345                 res = -EIO;
 346                 goto out_nobasetimereg;
 347         }
 348
 349         res = register_reboot_notifier(&sbc8360_notifier);
 350         if (res) {
 351                 pr_err("Failed to register reboot notifier\n");
 352                 goto out_noreboot;
 353         }
 354
 355         res = misc_register(&sbc8360_miscdev);
 356         if (res) {
 357                 pr_err("failed to register misc device\n");
 358                 goto out_nomisc;
 359         }
 360
 361         wd_margin = wd_times[timeout][0];
 362         wd_multiplier = wd_times[timeout][1];
 363
 364         if (wd_multiplier == 1)
 365                 mseconds = (wd_margin + 1) * 500;
 366         else if (wd_multiplier == 2)
 367                 mseconds = (wd_margin + 1) * 5000;
 368         else if (wd_multiplier == 3)
 369                 mseconds = (wd_margin + 1) * 50000;
 370         else if (wd_multiplier == 4)
 371                 mseconds = (wd_margin + 1) * 100000;
 372
 373         /* My kingdom for the ability to print "0.5 seconds" in the kernel! */
 374         pr_info("Timeout set at %ld ms\n", mseconds);
 375
 376         return 0;
 377
 378 out_nomisc:
 379         unregister_reboot_notifier(&sbc8360_notifier);
 380 out_noreboot:
 381         release_region(SBC8360_BASETIME, 1);
 382 out_nobasetimereg:
 383         release_region(SBC8360_ENABLE, 1);
 384 out:
 385         return res;
 386 }
 387
 388 static void __exit sbc8360_exit(void)
 389 {
 390         misc_deregister(&sbc8360_miscdev);
 391         unregister_reboot_notifier(&sbc8360_notifier);
 392         release_region(SBC8360_ENABLE, 1);
 393         release_region(SBC8360_BASETIME, 1);
 394 }
 395
 396 module_init(sbc8360_init);
 397 module_exit(sbc8360_exit);
 398
 399 MODULE_AUTHOR("Ian E. Morgan <imorgan@webcon.ca>");
 400 MODULE_DESCRIPTION("SBC8360 watchdog driver");
 401 MODULE_LICENSE("GPL");
 402 MODULE_VERSION("1.01");
 403
 404 /* end of sbc8360.c */