LXR linux/drivers/watchdog/machzwd.c

   1/*
   2 *  MachZ ZF-Logic Watchdog Timer driver for Linux
   3 *
   4 *
   5 *  This program is free software; you can redistribute it and/or
   6 *  modify it under the terms of the GNU General Public License
   7 *  as published by the Free Software Foundation; either version
   8 *  2 of the License, or (at your option) any later version.
   9 *
  10 *  The author does NOT admit liability nor provide warranty for
  11 *  any of this software. This material is provided "AS-IS" in
  12 *  the hope that it may be useful for others.
  13 *
  14 *  Author: Fernando Fuganti <fuganti@conectiva.com.br>
  15 *
  16 *  Based on sbc60xxwdt.c by Jakob Oestergaard
  17 *
  18 *
  19 *  We have two timers (wd#1, wd#2) driven by a 32 KHz clock with the
  20 *  following periods:
  21 *      wd#1 - 2 seconds;
  22 *      wd#2 - 7.2 ms;
  23 *  After the expiration of wd#1, it can generate a NMI, SCI, SMI, or
  24 *  a system RESET and it starts wd#2 that unconditionaly will RESET
  25 *  the system when the counter reaches zero.
  26 *
  27 *  14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
  28 *      Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
  29 */
  30
  31#include <linux/module.h>
  32#include <linux/moduleparam.h>
  33#include <linux/types.h>
  34#include <linux/timer.h>
  35#include <linux/jiffies.h>
  36#include <linux/miscdevice.h>
  37#include <linux/watchdog.h>
  38#include <linux/fs.h>
  39#include <linux/ioport.h>
  40#include <linux/notifier.h>
  41#include <linux/reboot.h>
  42#include <linux/init.h>
  43#include <linux/io.h>
  44#include <linux/uaccess.h>
  45
  46#include <asm/system.h>
  47
  48/* ports */
  49#define ZF_IOBASE       0x218
  50#define INDEX           0x218
  51#define DATA_B          0x219
  52#define DATA_W          0x21A
  53#define DATA_D          0x21A
  54
  55/* indexes */                   /* size */
  56#define ZFL_VERSION     0x02    /* 16   */
  57#define CONTROL         0x10    /* 16   */
  58#define STATUS          0x12    /* 8    */
  59#define COUNTER_1       0x0C    /* 16   */
  60#define COUNTER_2       0x0E    /* 8    */
  61#define PULSE_LEN       0x0F    /* 8    */
  62
  63/* controls */
  64#define ENABLE_WD1      0x0001
  65#define ENABLE_WD2      0x0002
  66#define RESET_WD1       0x0010
  67#define RESET_WD2       0x0020
  68#define GEN_SCI         0x0100
  69#define GEN_NMI         0x0200
  70#define GEN_SMI         0x0400
  71#define GEN_RESET       0x0800
  72
  73
  74/* utilities */
  75
  76#define WD1     0
  77#define WD2     1
  78
  79#define zf_writew(port, data)  { outb(port, INDEX); outw(data, DATA_W); }
  80#define zf_writeb(port, data)  { outb(port, INDEX); outb(data, DATA_B); }
  81#define zf_get_ZFL_version()   zf_readw(ZFL_VERSION)
  82
  83
  84static unsigned short zf_readw(unsigned char port)
  85{
  86        outb(port, INDEX);
  87        return inw(DATA_W);
  88}
  89
  90
  91MODULE_AUTHOR("Fernando Fuganti <fuganti@conectiva.com.br>");
  92MODULE_DESCRIPTION("MachZ ZF-Logic Watchdog driver");
  93MODULE_LICENSE("GPL");
  94MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  95
  96static int nowayout = WATCHDOG_NOWAYOUT;
  97module_param(nowayout, int, 0);
  98MODULE_PARM_DESC(nowayout,
  99                "Watchdog cannot be stopped once started (default="
 100                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 101
 102#define PFX "machzwd"
 103
 104static struct watchdog_info zf_info = {
 105        .options                = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 106        .firmware_version       = 1,
 107        .identity               = "ZF-Logic watchdog",
 108};
 109
 110
 111/*
 112 * action refers to action taken when watchdog resets
 113 * 0 = GEN_RESET
 114 * 1 = GEN_SMI
 115 * 2 = GEN_NMI
 116 * 3 = GEN_SCI
 117 * defaults to GEN_RESET (0)
 118 */
 119static int action;
 120module_param(action, int, 0);
 121MODULE_PARM_DESC(action, "after watchdog resets, generate: 0 = RESET(*)  1 = SMI  2 = NMI  3 = SCI");
 122
 123static void zf_ping(unsigned long data);
 124
 125static int zf_action = GEN_RESET;
 126static unsigned long zf_is_open;
 127static char zf_expect_close;
 128static DEFINE_SPINLOCK(zf_port_lock);
 129static DEFINE_TIMER(zf_timer, zf_ping, 0, 0);
 130static unsigned long next_heartbeat;
 131
 132
 133/* timeout for user land heart beat (10 seconds) */
 134#define ZF_USER_TIMEO (HZ*10)
 135
 136/* timeout for hardware watchdog (~500ms) */
 137#define ZF_HW_TIMEO (HZ/2)
 138
 139/* number of ticks on WD#1 (driven by a 32KHz clock, 2s) */
 140#define ZF_CTIMEOUT 0xffff
 141
 142#ifndef ZF_DEBUG
 143#       define dprintk(format, args...)
 144#else
 145#       define dprintk(format, args...) printk(KERN_DEBUG PFX ":%s:%d: " format, __func__, __LINE__ , ## args)
 146#endif
 147
 148
 149static inline void zf_set_status(unsigned char new)
 150{
 151        zf_writeb(STATUS, new);
 152}
 153
 154
 155/* CONTROL register functions */
 156
 157static inline unsigned short zf_get_control(void)
 158{
 159        return zf_readw(CONTROL);
 160}
 161
 162static inline void zf_set_control(unsigned short new)
 163{
 164        zf_writew(CONTROL, new);
 165}
 166
 167
 168/* WD#? counter functions */
 169/*
 170 *      Just set counter value
 171 */
 172
 173static inline void zf_set_timer(unsigned short new, unsigned char n)
 174{
 175        switch (n) {
 176        case WD1:
 177                zf_writew(COUNTER_1, new);
 178        case WD2:
 179                zf_writeb(COUNTER_2, new > 0xff ? 0xff : new);
 180        default:
 181                return;
 182        }
 183}
 184
 185/*
 186 * stop hardware timer
 187 */
 188static void zf_timer_off(void)
 189{
 190        unsigned int ctrl_reg = 0;
 191        unsigned long flags;
 192
 193        /* stop internal ping */
 194        del_timer_sync(&zf_timer);
 195
 196        spin_lock_irqsave(&zf_port_lock, flags);
 197        /* stop watchdog timer */
 198        ctrl_reg = zf_get_control();
 199        ctrl_reg |= (ENABLE_WD1|ENABLE_WD2);    /* disable wd1 and wd2 */
 200        ctrl_reg &= ~(ENABLE_WD1|ENABLE_WD2);
 201        zf_set_control(ctrl_reg);
 202        spin_unlock_irqrestore(&zf_port_lock, flags);
 203
 204        printk(KERN_INFO PFX ": Watchdog timer is now disabled\n");
 205}
 206
 207
 208/*
 209 * start hardware timer
 210 */
 211static void zf_timer_on(void)
 212{
 213        unsigned int ctrl_reg = 0;
 214        unsigned long flags;
 215
 216        spin_lock_irqsave(&zf_port_lock, flags);
 217
 218        zf_writeb(PULSE_LEN, 0xff);
 219
 220        zf_set_timer(ZF_CTIMEOUT, WD1);
 221
 222        /* user land ping */
 223        next_heartbeat = jiffies + ZF_USER_TIMEO;
 224
 225        /* start the timer for internal ping */
 226        mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
 227
 228        /* start watchdog timer */
 229        ctrl_reg = zf_get_control();
 230        ctrl_reg |= (ENABLE_WD1|zf_action);
 231        zf_set_control(ctrl_reg);
 232        spin_unlock_irqrestore(&zf_port_lock, flags);
 233
 234        printk(KERN_INFO PFX ": Watchdog timer is now enabled\n");
 235}
 236
 237
 238static void zf_ping(unsigned long data)
 239{
 240        unsigned int ctrl_reg = 0;
 241        unsigned long flags;
 242
 243        zf_writeb(COUNTER_2, 0xff);
 244
 245        if (time_before(jiffies, next_heartbeat)) {
 246                dprintk("time_before: %ld\n", next_heartbeat - jiffies);
 247                /*
 248                 * reset event is activated by transition from 0 to 1 on
 249                 * RESET_WD1 bit and we assume that it is already zero...
 250                 */
 251
 252                spin_lock_irqsave(&zf_port_lock, flags);
 253                ctrl_reg = zf_get_control();
 254                ctrl_reg |= RESET_WD1;
 255                zf_set_control(ctrl_reg);
 256
 257                /* ...and nothing changes until here */
 258                ctrl_reg &= ~(RESET_WD1);
 259                zf_set_control(ctrl_reg);
 260                spin_unlock_irqrestore(&zf_port_lock, flags);
 261
 262                mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
 263        } else
 264                printk(KERN_CRIT PFX ": I will reset your machine\n");
 265}
 266
 267static ssize_t zf_write(struct file *file, const char __user *buf, size_t count,
 268                                                                loff_t *ppos)
 269{
 270        /* See if we got the magic character */
 271        if (count) {
 272                /*
 273                 * no need to check for close confirmation
 274                 * no way to disable watchdog ;)
 275                 */
 276                if (!nowayout) {
 277                        size_t ofs;
 278                        /*
 279                         * note: just in case someone wrote the magic character
 280                         * five months ago...
 281                         */
 282                        zf_expect_close = 0;
 283
 284                        /* now scan */
 285                        for (ofs = 0; ofs != count; ofs++) {
 286                                char c;
 287                                if (get_user(c, buf + ofs))
 288                                        return -EFAULT;
 289                                if (c == 'V') {
 290                                        zf_expect_close = 42;
 291                                        dprintk("zf_expect_close = 42\n");
 292                                }
 293                        }
 294                }
 295
 296                /*
 297                 * Well, anyhow someone wrote to us,
 298                 * we should return that favour
 299                 */
 300                next_heartbeat = jiffies + ZF_USER_TIMEO;
 301                dprintk("user ping at %ld\n", jiffies);
 302        }
 303        return count;
 304}
 305
 306static long zf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 307{
 308        void __user *argp = (void __user *)arg;
 309        int __user *p = argp;
 310        switch (cmd) {
 311        case WDIOC_GETSUPPORT:
 312                if (copy_to_user(argp, &zf_info, sizeof(zf_info)))
 313                        return -EFAULT;
 314                break;
 315        case WDIOC_GETSTATUS:
 316        case WDIOC_GETBOOTSTATUS:
 317                return put_user(0, p);
 318        case WDIOC_KEEPALIVE:
 319                zf_ping(0);
 320                break;
 321        default:
 322                return -ENOTTY;
 323        }
 324        return 0;
 325}
 326
 327static int zf_open(struct inode *inode, struct file *file)
 328{
 329        if (test_and_set_bit(0, &zf_is_open))
 330                return -EBUSY;
 331        if (nowayout)
 332                __module_get(THIS_MODULE);
 333        zf_timer_on();
 334        return nonseekable_open(inode, file);
 335}
 336
 337static int zf_close(struct inode *inode, struct file *file)
 338{
 339        if (zf_expect_close == 42)
 340                zf_timer_off();
 341        else {
 342                del_timer(&zf_timer);
 343                printk(KERN_ERR PFX ": device file closed unexpectedly. Will not stop the WDT!\n");
 344        }
 345        clear_bit(0, &zf_is_open);
 346        zf_expect_close = 0;
 347        return 0;
 348}
 349
 350/*
 351 * Notifier for system down
 352 */
 353
 354static int zf_notify_sys(struct notifier_block *this, unsigned long code,
 355                                                                void *unused)
 356{
 357        if (code == SYS_DOWN || code == SYS_HALT)
 358                zf_timer_off();
 359        return NOTIFY_DONE;
 360}
 361
 362static const struct file_operations zf_fops = {
 363        .owner          = THIS_MODULE,
 364        .llseek         = no_llseek,
 365        .write          = zf_write,
 366        .unlocked_ioctl = zf_ioctl,
 367        .open           = zf_open,
 368        .release        = zf_close,
 369};
 370
 371static struct miscdevice zf_miscdev = {
 372        .minor = WATCHDOG_MINOR,
 373        .name = "watchdog",
 374        .fops = &zf_fops,
 375};
 376
 377
 378/*
 379 * The device needs to learn about soft shutdowns in order to
 380 * turn the timebomb registers off.
 381 */
 382static struct notifier_block zf_notifier = {
 383        .notifier_call = zf_notify_sys,
 384};
 385
 386static void __init zf_show_action(int act)
 387{
 388        char *str[] = { "RESET", "SMI", "NMI", "SCI" };
 389
 390        printk(KERN_INFO PFX ": Watchdog using action = %s\n", str[act]);
 391}
 392
 393static int __init zf_init(void)
 394{
 395        int ret;
 396
 397        printk(KERN_INFO PFX
 398                ": MachZ ZF-Logic Watchdog driver initializing.\n");
 399
 400        ret = zf_get_ZFL_version();
 401        if (!ret || ret == 0xffff) {
 402                printk(KERN_WARNING PFX ": no ZF-Logic found\n");
 403                return -ENODEV;
 404        }
 405
 406        if (action <= 3 && action >= 0)
 407                zf_action = zf_action >> action;
 408        else
 409                action = 0;
 410
 411        zf_show_action(action);
 412
 413        if (!request_region(ZF_IOBASE, 3, "MachZ ZFL WDT")) {
 414                printk(KERN_ERR "cannot reserve I/O ports at %d\n",
 415                                                        ZF_IOBASE);
 416                ret = -EBUSY;
 417                goto no_region;
 418        }
 419
 420        ret = register_reboot_notifier(&zf_notifier);
 421        if (ret) {
 422                printk(KERN_ERR "can't register reboot notifier (err=%d)\n",
 423                                                                        ret);
 424                goto no_reboot;
 425        }
 426
 427        ret = misc_register(&zf_miscdev);
 428        if (ret) {
 429                printk(KERN_ERR "can't misc_register on minor=%d\n",
 430                                                        WATCHDOG_MINOR);
 431                goto no_misc;
 432        }
 433
 434        zf_set_status(0);
 435        zf_set_control(0);
 436
 437        return 0;
 438
 439no_misc:
 440        unregister_reboot_notifier(&zf_notifier);
 441no_reboot:
 442        release_region(ZF_IOBASE, 3);
 443no_region:
 444        return ret;
 445}
 446
 447
 448static void __exit zf_exit(void)
 449{
 450        zf_timer_off();
 451
 452        misc_deregister(&zf_miscdev);
 453        unregister_reboot_notifier(&zf_notifier);
 454        release_region(ZF_IOBASE, 3);
 455}
 456
 457module_init(zf_init);
 458module_exit(zf_exit);
 459