linux/drivers/watchdog/ib700wdt.c
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   1/*
   2 *      IB700 Single Board Computer WDT driver
   3 *
   4 *      (c) Copyright 2001 Charles Howes <chowes@vsol.net>
   5 *
   6 *      Based on advantechwdt.c which is based on acquirewdt.c which
   7 *      is based on wdt.c.
   8 *
   9 *      (c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
  10 *
  11 *      Based on acquirewdt.c which is based on wdt.c.
  12 *      Original copyright messages:
  13 *
  14 *      (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
  15 *                                              All Rights Reserved.
  16 *
  17 *      This program is free software; you can redistribute it and/or
  18 *      modify it under the terms of the GNU General Public License
  19 *      as published by the Free Software Foundation; either version
  20 *      2 of the License, or (at your option) any later version.
  21 *
  22 *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  23 *      warranty for any of this software. This material is provided
  24 *      "AS-IS" and at no charge.
  25 *
  26 *      (c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
  27 *
  28 *      14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
  29 *           Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
  30 *           Added timeout module option to override default
  31 *
  32 */
  33
  34#include <linux/module.h>
  35#include <linux/types.h>
  36#include <linux/miscdevice.h>
  37#include <linux/watchdog.h>
  38#include <linux/ioport.h>
  39#include <linux/fs.h>
  40#include <linux/init.h>
  41#include <linux/spinlock.h>
  42#include <linux/moduleparam.h>
  43#include <linux/platform_device.h>
  44#include <linux/io.h>
  45#include <linux/uaccess.h>
  46
  47#include <asm/system.h>
  48
  49static struct platform_device *ibwdt_platform_device;
  50static unsigned long ibwdt_is_open;
  51static DEFINE_SPINLOCK(ibwdt_lock);
  52static char expect_close;
  53
  54/* Module information */
  55#define DRV_NAME "ib700wdt"
  56#define PFX DRV_NAME ": "
  57
  58/*
  59 *
  60 * Watchdog Timer Configuration
  61 *
  62 * The function of the watchdog timer is to reset the system
  63 * automatically and is defined at I/O port 0443H.  To enable the
  64 * watchdog timer and allow the system to reset, write I/O port 0443H.
  65 * To disable the timer, write I/O port 0441H for the system to stop the
  66 * watchdog function.  The timer has a tolerance of 20% for its
  67 * intervals.
  68 *
  69 * The following describes how the timer should be programmed.
  70 *
  71 * Enabling Watchdog:
  72 * MOV AX,000FH (Choose the values from 0 to F)
  73 * MOV DX,0443H
  74 * OUT DX,AX
  75 *
  76 * Disabling Watchdog:
  77 * MOV AX,000FH (Any value is fine.)
  78 * MOV DX,0441H
  79 * OUT DX,AX
  80 *
  81 * Watchdog timer control table:
  82 * Level   Value  Time/sec | Level Value Time/sec
  83 *   1       F       0     |   9     7      16
  84 *   2       E       2     |   10    6      18
  85 *   3       D       4     |   11    5      20
  86 *   4       C       6     |   12    4      22
  87 *   5       B       8     |   13    3      24
  88 *   6       A       10    |   14    2      26
  89 *   7       9       12    |   15    1      28
  90 *   8       8       14    |   16    0      30
  91 *
  92 */
  93
  94static int wd_times[] = {
  95        30,     /* 0x0 */
  96        28,     /* 0x1 */
  97        26,     /* 0x2 */
  98        24,     /* 0x3 */
  99        22,     /* 0x4 */
 100        20,     /* 0x5 */
 101        18,     /* 0x6 */
 102        16,     /* 0x7 */
 103        14,     /* 0x8 */
 104        12,     /* 0x9 */
 105        10,     /* 0xA */
 106        8,      /* 0xB */
 107        6,      /* 0xC */
 108        4,      /* 0xD */
 109        2,      /* 0xE */
 110        0,      /* 0xF */
 111};
 112
 113#define WDT_STOP 0x441
 114#define WDT_START 0x443
 115
 116/* Default timeout */
 117#define WD_TIMO 0               /* 30 seconds +/- 20%, from table */
 118
 119static int wd_margin = WD_TIMO;
 120
 121static int nowayout = WATCHDOG_NOWAYOUT;
 122module_param(nowayout, int, 0);
 123MODULE_PARM_DESC(nowayout,
 124                "Watchdog cannot be stopped once started (default="
 125                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 126
 127
 128/*
 129 *      Watchdog Operations
 130 */
 131
 132static void ibwdt_ping(void)
 133{
 134        spin_lock(&ibwdt_lock);
 135
 136        /* Write a watchdog value */
 137        outb_p(wd_margin, WDT_START);
 138
 139        spin_unlock(&ibwdt_lock);
 140}
 141
 142static void ibwdt_disable(void)
 143{
 144        spin_lock(&ibwdt_lock);
 145        outb_p(0, WDT_STOP);
 146        spin_unlock(&ibwdt_lock);
 147}
 148
 149static int ibwdt_set_heartbeat(int t)
 150{
 151        int i;
 152
 153        if ((t < 0) || (t > 30))
 154                return -EINVAL;
 155
 156        for (i = 0x0F; i > -1; i--)
 157                if (wd_times[i] >= t)
 158                        break;
 159        wd_margin = i;
 160        return 0;
 161}
 162
 163/*
 164 *      /dev/watchdog handling
 165 */
 166
 167static ssize_t ibwdt_write(struct file *file, const char __user *buf,
 168                                                size_t count, loff_t *ppos)
 169{
 170        if (count) {
 171                if (!nowayout) {
 172                        size_t i;
 173
 174                        /* In case it was set long ago */
 175                        expect_close = 0;
 176
 177                        for (i = 0; i != count; i++) {
 178                                char c;
 179                                if (get_user(c, buf + i))
 180                                        return -EFAULT;
 181                                if (c == 'V')
 182                                        expect_close = 42;
 183                        }
 184                }
 185                ibwdt_ping();
 186        }
 187        return count;
 188}
 189
 190static long ibwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 191{
 192        int new_margin;
 193        void __user *argp = (void __user *)arg;
 194        int __user *p = argp;
 195
 196        static struct watchdog_info ident = {
 197                .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
 198                                                        | WDIOF_MAGICCLOSE,
 199                .firmware_version = 1,
 200                .identity = "IB700 WDT",
 201        };
 202
 203        switch (cmd) {
 204        case WDIOC_GETSUPPORT:
 205                if (copy_to_user(argp, &ident, sizeof(ident)))
 206                        return -EFAULT;
 207                break;
 208
 209        case WDIOC_GETSTATUS:
 210        case WDIOC_GETBOOTSTATUS:
 211                return put_user(0, p);
 212
 213        case WDIOC_SETOPTIONS:
 214        {
 215                int options, retval = -EINVAL;
 216
 217                if (get_user(options, p))
 218                        return -EFAULT;
 219
 220                if (options & WDIOS_DISABLECARD) {
 221                        ibwdt_disable();
 222                        retval = 0;
 223                }
 224                if (options & WDIOS_ENABLECARD) {
 225                        ibwdt_ping();
 226                        retval = 0;
 227                }
 228                return retval;
 229        }
 230        case WDIOC_KEEPALIVE:
 231                ibwdt_ping();
 232                break;
 233
 234        case WDIOC_SETTIMEOUT:
 235                if (get_user(new_margin, p))
 236                        return -EFAULT;
 237                if (ibwdt_set_heartbeat(new_margin))
 238                        return -EINVAL;
 239                ibwdt_ping();
 240                /* Fall */
 241
 242        case WDIOC_GETTIMEOUT:
 243                return put_user(wd_times[wd_margin], p);
 244
 245        default:
 246                return -ENOTTY;
 247        }
 248        return 0;
 249}
 250
 251static int ibwdt_open(struct inode *inode, struct file *file)
 252{
 253        if (test_and_set_bit(0, &ibwdt_is_open))
 254                return -EBUSY;
 255        if (nowayout)
 256                __module_get(THIS_MODULE);
 257
 258        /* Activate */
 259        ibwdt_ping();
 260        return nonseekable_open(inode, file);
 261}
 262
 263static int ibwdt_close(struct inode *inode, struct file *file)
 264{
 265        if (expect_close == 42) {
 266                ibwdt_disable();
 267        } else {
 268                printk(KERN_CRIT PFX
 269                     "WDT device closed unexpectedly.  WDT will not stop!\n");
 270                ibwdt_ping();
 271        }
 272        clear_bit(0, &ibwdt_is_open);
 273        expect_close = 0;
 274        return 0;
 275}
 276
 277/*
 278 *      Kernel Interfaces
 279 */
 280
 281static const struct file_operations ibwdt_fops = {
 282        .owner          = THIS_MODULE,
 283        .llseek         = no_llseek,
 284        .write          = ibwdt_write,
 285        .unlocked_ioctl = ibwdt_ioctl,
 286        .open           = ibwdt_open,
 287        .release        = ibwdt_close,
 288};
 289
 290static struct miscdevice ibwdt_miscdev = {
 291        .minor = WATCHDOG_MINOR,
 292        .name = "watchdog",
 293        .fops = &ibwdt_fops,
 294};
 295
 296/*
 297 *      Init & exit routines
 298 */
 299
 300static int __devinit ibwdt_probe(struct platform_device *dev)
 301{
 302        int res;
 303
 304#if WDT_START != WDT_STOP
 305        if (!request_region(WDT_STOP, 1, "IB700 WDT")) {
 306                printk(KERN_ERR PFX "STOP method I/O %X is not available.\n",
 307                                                                WDT_STOP);
 308                res = -EIO;
 309                goto out_nostopreg;
 310        }
 311#endif
 312
 313        if (!request_region(WDT_START, 1, "IB700 WDT")) {
 314                printk(KERN_ERR PFX "START method I/O %X is not available.\n",
 315                                                                WDT_START);
 316                res = -EIO;
 317                goto out_nostartreg;
 318        }
 319
 320        res = misc_register(&ibwdt_miscdev);
 321        if (res) {
 322                printk(KERN_ERR PFX "failed to register misc device\n");
 323                goto out_nomisc;
 324        }
 325        return 0;
 326
 327out_nomisc:
 328        release_region(WDT_START, 1);
 329out_nostartreg:
 330#if WDT_START != WDT_STOP
 331        release_region(WDT_STOP, 1);
 332#endif
 333out_nostopreg:
 334        return res;
 335}
 336
 337static int __devexit ibwdt_remove(struct platform_device *dev)
 338{
 339        misc_deregister(&ibwdt_miscdev);
 340        release_region(WDT_START, 1);
 341#if WDT_START != WDT_STOP
 342        release_region(WDT_STOP, 1);
 343#endif
 344        return 0;
 345}
 346
 347static void ibwdt_shutdown(struct platform_device *dev)
 348{
 349        /* Turn the WDT off if we have a soft shutdown */
 350        ibwdt_disable();
 351}
 352
 353static struct platform_driver ibwdt_driver = {
 354        .probe          = ibwdt_probe,
 355        .remove         = __devexit_p(ibwdt_remove),
 356        .shutdown       = ibwdt_shutdown,
 357        .driver         = {
 358                .owner  = THIS_MODULE,
 359                .name   = DRV_NAME,
 360        },
 361};
 362
 363static int __init ibwdt_init(void)
 364{
 365        int err;
 366
 367        printk(KERN_INFO PFX
 368                "WDT driver for IB700 single board computer initialising.\n");
 369
 370        err = platform_driver_register(&ibwdt_driver);
 371        if (err)
 372                return err;
 373
 374        ibwdt_platform_device = platform_device_register_simple(DRV_NAME,
 375                                                                -1, NULL, 0);
 376        if (IS_ERR(ibwdt_platform_device)) {
 377                err = PTR_ERR(ibwdt_platform_device);
 378                goto unreg_platform_driver;
 379        }
 380
 381        return 0;
 382
 383unreg_platform_driver:
 384        platform_driver_unregister(&ibwdt_driver);
 385        return err;
 386}
 387
 388static void __exit ibwdt_exit(void)
 389{
 390        platform_device_unregister(ibwdt_platform_device);
 391        platform_driver_unregister(&ibwdt_driver);
 392        printk(KERN_INFO PFX "Watchdog Module Unloaded.\n");
 393}
 394
 395module_init(ibwdt_init);
 396module_exit(ibwdt_exit);
 397
 398MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
 399MODULE_DESCRIPTION("IB700 SBC watchdog driver");
 400MODULE_LICENSE("GPL");
 401MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 402
 403/* end of ib700wdt.c */
 404