drivers/watchdog/ib700wdt.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *      IB700 Single Board Computer WDT driver
   4  *
   5  *      (c) Copyright 2001 Charles Howes <chowes@vsol.net>
   6  *
   7  *      Based on advantechwdt.c which is based on acquirewdt.c which
   8  *      is based on wdt.c.
   9  *
  10  *      (c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
  11  *
  12  *      Based on acquirewdt.c which is based on wdt.c.
  13  *      Original copyright messages:
  14  *
  15  *      (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
  16  *                                              All Rights Reserved.
  17  *
  18  *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  19  *      warranty for any of this software. This material is provided
  20  *      "AS-IS" and at no charge.
  21  *
  22  *      (c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
  23  *
  24  *      14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
  25  *           Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
  26  *           Added timeout module option to override default
  27  *
  28  */
  29
  30 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  31
  32 #include <linux/module.h>
  33 #include <linux/types.h>
  34 #include <linux/miscdevice.h>
  35 #include <linux/watchdog.h>
  36 #include <linux/ioport.h>
  37 #include <linux/fs.h>
  38 #include <linux/init.h>
  39 #include <linux/spinlock.h>
  40 #include <linux/moduleparam.h>
  41 #include <linux/platform_device.h>
  42 #include <linux/io.h>
  43 #include <linux/uaccess.h>
  44
  45
  46 static struct platform_device *ibwdt_platform_device;
  47 static unsigned long ibwdt_is_open;
  48 static DEFINE_SPINLOCK(ibwdt_lock);
  49 static char expect_close;
  50
  51 /* Module information */
  52 #define DRV_NAME "ib700wdt"
  53
  54 /*
  55  *
  56  * Watchdog Timer Configuration
  57  *
  58  * The function of the watchdog timer is to reset the system
  59  * automatically and is defined at I/O port 0443H.  To enable the
  60  * watchdog timer and allow the system to reset, write I/O port 0443H.
  61  * To disable the timer, write I/O port 0441H for the system to stop the
  62  * watchdog function.  The timer has a tolerance of 20% for its
  63  * intervals.
  64  *
  65  * The following describes how the timer should be programmed.
  66  *
  67  * Enabling Watchdog:
  68  * MOV AX,000FH (Choose the values from 0 to F)
  69  * MOV DX,0443H
  70  * OUT DX,AX
  71  *
  72  * Disabling Watchdog:
  73  * MOV AX,000FH (Any value is fine.)
  74  * MOV DX,0441H
  75  * OUT DX,AX
  76  *
  77  * Watchdog timer control table:
  78  * Level   Value  Time/sec | Level Value Time/sec
  79  *   1       F       0     |   9     7      16
  80  *   2       E       2     |   10    6      18
  81  *   3       D       4     |   11    5      20
  82  *   4       C       6     |   12    4      22
  83  *   5       B       8     |   13    3      24
  84  *   6       A       10    |   14    2      26
  85  *   7       9       12    |   15    1      28
  86  *   8       8       14    |   16    0      30
  87  *
  88  */
  89
  90 #define WDT_STOP 0x441
  91 #define WDT_START 0x443
  92
  93 /* Default timeout */
  94 #define WATCHDOG_TIMEOUT 30             /* 30 seconds +/- 20% */
  95 static int timeout = WATCHDOG_TIMEOUT;  /* in seconds */
  96 module_param(timeout, int, 0);
  97 MODULE_PARM_DESC(timeout,
  98         "Watchdog timeout in seconds. 0<= timeout <=30, default="
  99                 __MODULE_STRING(WATCHDOG_TIMEOUT) ".");
 100
 101 static bool nowayout = WATCHDOG_NOWAYOUT;
 102 module_param(nowayout, bool, 0);
 103 MODULE_PARM_DESC(nowayout,
 104                 "Watchdog cannot be stopped once started (default="
 105                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 106
 107
 108 /*
 109  *      Watchdog Operations
 110  */
 111
 112 static void ibwdt_ping(void)
 113 {
 114         int wd_margin = 15 - ((timeout + 1) / 2);
 115
 116         spin_lock(&ibwdt_lock);
 117
 118         /* Write a watchdog value */
 119         outb_p(wd_margin, WDT_START);
 120
 121         spin_unlock(&ibwdt_lock);
 122 }
 123
 124 static void ibwdt_disable(void)
 125 {
 126         spin_lock(&ibwdt_lock);
 127         outb_p(0, WDT_STOP);
 128         spin_unlock(&ibwdt_lock);
 129 }
 130
 131 static int ibwdt_set_heartbeat(int t)
 132 {
 133         if (t < 0 || t > 30)
 134                 return -EINVAL;
 135
 136         timeout = t;
 137         return 0;
 138 }
 139
 140 /*
 141  *      /dev/watchdog handling
 142  */
 143
 144 static ssize_t ibwdt_write(struct file *file, const char __user *buf,
 145                                                 size_t count, loff_t *ppos)
 146 {
 147         if (count) {
 148                 if (!nowayout) {
 149                         size_t i;
 150
 151                         /* In case it was set long ago */
 152                         expect_close = 0;
 153
 154                         for (i = 0; i != count; i++) {
 155                                 char c;
 156                                 if (get_user(c, buf + i))
 157                                         return -EFAULT;
 158                                 if (c == 'V')
 159                                         expect_close = 42;
 160                         }
 161                 }
 162                 ibwdt_ping();
 163         }
 164         return count;
 165 }
 166
 167 static long ibwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 168 {
 169         int new_margin;
 170         void __user *argp = (void __user *)arg;
 171         int __user *p = argp;
 172
 173         static const struct watchdog_info ident = {
 174                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
 175                                                         | WDIOF_MAGICCLOSE,
 176                 .firmware_version = 1,
 177                 .identity = "IB700 WDT",
 178         };
 179
 180         switch (cmd) {
 181         case WDIOC_GETSUPPORT:
 182                 if (copy_to_user(argp, &ident, sizeof(ident)))
 183                         return -EFAULT;
 184                 break;
 185
 186         case WDIOC_GETSTATUS:
 187         case WDIOC_GETBOOTSTATUS:
 188                 return put_user(0, p);
 189
 190         case WDIOC_SETOPTIONS:
 191         {
 192                 int options, retval = -EINVAL;
 193
 194                 if (get_user(options, p))
 195                         return -EFAULT;
 196
 197                 if (options & WDIOS_DISABLECARD) {
 198                         ibwdt_disable();
 199                         retval = 0;
 200                 }
 201                 if (options & WDIOS_ENABLECARD) {
 202                         ibwdt_ping();
 203                         retval = 0;
 204                 }
 205                 return retval;
 206         }
 207         case WDIOC_KEEPALIVE:
 208                 ibwdt_ping();
 209                 break;
 210
 211         case WDIOC_SETTIMEOUT:
 212                 if (get_user(new_margin, p))
 213                         return -EFAULT;
 214                 if (ibwdt_set_heartbeat(new_margin))
 215                         return -EINVAL;
 216                 ibwdt_ping();
 217                 fallthrough;
 218
 219         case WDIOC_GETTIMEOUT:
 220                 return put_user(timeout, p);
 221
 222         default:
 223                 return -ENOTTY;
 224         }
 225         return 0;
 226 }
 227
 228 static int ibwdt_open(struct inode *inode, struct file *file)
 229 {
 230         if (test_and_set_bit(0, &ibwdt_is_open))
 231                 return -EBUSY;
 232         if (nowayout)
 233                 __module_get(THIS_MODULE);
 234
 235         /* Activate */
 236         ibwdt_ping();
 237         return stream_open(inode, file);
 238 }
 239
 240 static int ibwdt_close(struct inode *inode, struct file *file)
 241 {
 242         if (expect_close == 42) {
 243                 ibwdt_disable();
 244         } else {
 245                 pr_crit("WDT device closed unexpectedly.  WDT will not stop!\n");
 246                 ibwdt_ping();
 247         }
 248         clear_bit(0, &ibwdt_is_open);
 249         expect_close = 0;
 250         return 0;
 251 }
 252
 253 /*
 254  *      Kernel Interfaces
 255  */
 256
 257 static const struct file_operations ibwdt_fops = {
 258         .owner          = THIS_MODULE,
 259         .llseek         = no_llseek,
 260         .write          = ibwdt_write,
 261         .unlocked_ioctl = ibwdt_ioctl,
 262         .compat_ioctl   = compat_ptr_ioctl,
 263         .open           = ibwdt_open,
 264         .release        = ibwdt_close,
 265 };
 266
 267 static struct miscdevice ibwdt_miscdev = {
 268         .minor = WATCHDOG_MINOR,
 269         .name = "watchdog",
 270         .fops = &ibwdt_fops,
 271 };
 272
 273 /*
 274  *      Init & exit routines
 275  */
 276
 277 static int __init ibwdt_probe(struct platform_device *dev)
 278 {
 279         int res;
 280
 281 #if WDT_START != WDT_STOP
 282         if (!request_region(WDT_STOP, 1, "IB700 WDT")) {
 283                 pr_err("STOP method I/O %X is not available\n", WDT_STOP);
 284                 res = -EIO;
 285                 goto out_nostopreg;
 286         }
 287 #endif
 288
 289         if (!request_region(WDT_START, 1, "IB700 WDT")) {
 290                 pr_err("START method I/O %X is not available\n", WDT_START);
 291                 res = -EIO;
 292                 goto out_nostartreg;
 293         }
 294
 295         /* Check that the heartbeat value is within it's range ;
 296          * if not reset to the default */
 297         if (ibwdt_set_heartbeat(timeout)) {
 298                 ibwdt_set_heartbeat(WATCHDOG_TIMEOUT);
 299                 pr_info("timeout value must be 0<=x<=30, using %d\n", timeout);
 300         }
 301
 302         res = misc_register(&ibwdt_miscdev);
 303         if (res) {
 304                 pr_err("failed to register misc device\n");
 305                 goto out_nomisc;
 306         }
 307         return 0;
 308
 309 out_nomisc:
 310         release_region(WDT_START, 1);
 311 out_nostartreg:
 312 #if WDT_START != WDT_STOP
 313         release_region(WDT_STOP, 1);
 314 #endif
 315 out_nostopreg:
 316         return res;
 317 }
 318
 319 static int ibwdt_remove(struct platform_device *dev)
 320 {
 321         misc_deregister(&ibwdt_miscdev);
 322         release_region(WDT_START, 1);
 323 #if WDT_START != WDT_STOP
 324         release_region(WDT_STOP, 1);
 325 #endif
 326         return 0;
 327 }
 328
 329 static void ibwdt_shutdown(struct platform_device *dev)
 330 {
 331         /* Turn the WDT off if we have a soft shutdown */
 332         ibwdt_disable();
 333 }
 334
 335 static struct platform_driver ibwdt_driver = {
 336         .remove         = ibwdt_remove,
 337         .shutdown       = ibwdt_shutdown,
 338         .driver         = {
 339                 .name   = DRV_NAME,
 340         },
 341 };
 342
 343 static int __init ibwdt_init(void)
 344 {
 345         int err;
 346
 347         pr_info("WDT driver for IB700 single board computer initialising\n");
 348
 349         ibwdt_platform_device = platform_device_register_simple(DRV_NAME,
 350                                                                 -1, NULL, 0);
 351         if (IS_ERR(ibwdt_platform_device))
 352                 return PTR_ERR(ibwdt_platform_device);
 353
 354         err = platform_driver_probe(&ibwdt_driver, ibwdt_probe);
 355         if (err)
 356                 goto unreg_platform_device;
 357
 358         return 0;
 359
 360 unreg_platform_device:
 361         platform_device_unregister(ibwdt_platform_device);
 362         return err;
 363 }
 364
 365 static void __exit ibwdt_exit(void)
 366 {
 367         platform_device_unregister(ibwdt_platform_device);
 368         platform_driver_unregister(&ibwdt_driver);
 369         pr_info("Watchdog Module Unloaded\n");
 370 }
 371
 372 module_init(ibwdt_init);
 373 module_exit(ibwdt_exit);
 374
 375 MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
 376 MODULE_DESCRIPTION("IB700 SBC watchdog driver");
 377 MODULE_LICENSE("GPL");
 378
 379 /* end of ib700wdt.c */