drivers/watchdog/sc520_wdt.c

   1 /*
   2  *      AMD Elan SC520 processor Watchdog Timer driver
   3  *
   4  *      Based on acquirewdt.c by Alan Cox,
   5  *           and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
   6  *
   7  *      This program is free software; you can redistribute it and/or
   8  *      modify it under the terms of the GNU General Public License
   9  *      as published by the Free Software Foundation; either version
  10  *      2 of the License, or (at your option) any later version.
  11  *
  12  *      The authors do NOT admit liability nor provide warranty for
  13  *      any of this software. This material is provided "AS-IS" in
  14  *      the hope that it may be useful for others.
  15  *
  16  *      (c) Copyright 2001    Scott Jennings <linuxdrivers@oro.net>
  17  *           9/27 - 2001      [Initial release]
  18  *
  19  *      Additional fixes Alan Cox
  20  *      -       Fixed formatting
  21  *      -       Removed debug printks
  22  *      -       Fixed SMP built kernel deadlock
  23  *      -       Switched to private locks not lock_kernel
  24  *      -       Used ioremap/writew/readw
  25  *      -       Added NOWAYOUT support
  26  *      4/12 - 2002 Changes by Rob Radez <rob@osinvestor.com>
  27  *      -       Change comments
  28  *      -       Eliminate fop_llseek
  29  *      -       Change CONFIG_WATCHDOG_NOWAYOUT semantics
  30  *      -       Add KERN_* tags to printks
  31  *      -       fix possible wdt_is_open race
  32  *      -       Report proper capabilities in watchdog_info
  33  *      -       Add WDIOC_{GETSTATUS, GETBOOTSTATUS, SETTIMEOUT,
  34  *              GETTIMEOUT, SETOPTIONS} ioctls
  35  *      09/8 - 2003 Changes by Wim Van Sebroeck <wim@iguana.be>
  36  *      -       cleanup of trailing spaces
  37  *      -       added extra printk's for startup problems
  38  *      -       use module_param
  39  *      -       made timeout (the emulated heartbeat) a module_param
  40  *      -       made the keepalive ping an internal subroutine
  41  *      3/27 - 2004 Changes by Sean Young <sean@mess.org>
  42  *      -       set MMCR_BASE to 0xfffef000
  43  *      -       CBAR does not need to be read
  44  *      -       removed debugging printks
  45  *
  46  *  This WDT driver is different from most other Linux WDT
  47  *  drivers in that the driver will ping the watchdog by itself,
  48  *  because this particular WDT has a very short timeout (1.6
  49  *  seconds) and it would be insane to count on any userspace
  50  *  daemon always getting scheduled within that time frame.
  51  *
  52  *  This driver uses memory mapped IO, and spinlock.
  53  */
  54
  55 #include <linux/module.h>
  56 #include <linux/moduleparam.h>
  57 #include <linux/types.h>
  58 #include <linux/timer.h>
  59 #include <linux/miscdevice.h>
  60 #include <linux/watchdog.h>
  61 #include <linux/fs.h>
  62 #include <linux/ioport.h>
  63 #include <linux/notifier.h>
  64 #include <linux/reboot.h>
  65 #include <linux/init.h>
  66 #include <linux/jiffies.h>
  67 #include <linux/io.h>
  68 #include <linux/uaccess.h>
  69
  70
  71 #define OUR_NAME "sc520_wdt"
  72 #define PFX OUR_NAME ": "
  73
  74 /*
  75  * The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7)
  76  *
  77  *   0: 492us    2: 1.01s    4: 4.03s   6: 16.22s
  78  *   1: 503ms    3: 2.01s    5: 8.05s   7: 32.21s
  79  *
  80  * We will program the SC520 watchdog for a timeout of 2.01s.
  81  * If we reset the watchdog every ~250ms we should be safe.
  82  */
  83
  84 #define WDT_INTERVAL (HZ/4+1)
  85
  86 /*
  87  * We must not require too good response from the userspace daemon.
  88  * Here we require the userspace daemon to send us a heartbeat
  89  * char to /dev/watchdog every 30 seconds.
  90  */
  91
  92 #define WATCHDOG_TIMEOUT 30             /* 30 sec default timeout */
  93 /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
  94 static int timeout = WATCHDOG_TIMEOUT;
  95 module_param(timeout, int, 0);
  96 MODULE_PARM_DESC(timeout,
  97         "Watchdog timeout in seconds. (1 <= timeout <= 3600, default="
  98                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  99
 100 static int nowayout = WATCHDOG_NOWAYOUT;
 101 module_param(nowayout, int, 0);
 102 MODULE_PARM_DESC(nowayout,
 103                 "Watchdog cannot be stopped once started (default="
 104                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 105
 106 /*
 107  * AMD Elan SC520 - Watchdog Timer Registers
 108  */
 109 #define MMCR_BASE       0xfffef000      /* The default base address */
 110 #define OFFS_WDTMRCTL   0xCB0   /* Watchdog Timer Control Register */
 111
 112 /* WDT Control Register bit definitions */
 113 #define WDT_EXP_SEL_01  0x0001  /* [01] Time-out = 496 us (with 33 Mhz clk). */
 114 #define WDT_EXP_SEL_02  0x0002  /* [02] Time-out = 508 ms (with 33 Mhz clk). */
 115 #define WDT_EXP_SEL_03  0x0004  /* [03] Time-out = 1.02 s (with 33 Mhz clk). */
 116 #define WDT_EXP_SEL_04  0x0008  /* [04] Time-out = 2.03 s (with 33 Mhz clk). */
 117 #define WDT_EXP_SEL_05  0x0010  /* [05] Time-out = 4.07 s (with 33 Mhz clk). */
 118 #define WDT_EXP_SEL_06  0x0020  /* [06] Time-out = 8.13 s (with 33 Mhz clk). */
 119 #define WDT_EXP_SEL_07  0x0040  /* [07] Time-out = 16.27s (with 33 Mhz clk). */
 120 #define WDT_EXP_SEL_08  0x0080  /* [08] Time-out = 32.54s (with 33 Mhz clk). */
 121 #define WDT_IRQ_FLG     0x1000  /* [12] Interrupt Request Flag */
 122 #define WDT_WRST_ENB    0x4000  /* [14] Watchdog Timer Reset Enable */
 123 #define WDT_ENB         0x8000  /* [15] Watchdog Timer Enable */
 124
 125 static __u16 __iomem *wdtmrctl;
 126
 127 static void wdt_timer_ping(unsigned long);
 128 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
 129 static unsigned long next_heartbeat;
 130 static unsigned long wdt_is_open;
 131 static char wdt_expect_close;
 132 static DEFINE_SPINLOCK(wdt_spinlock);
 133
 134 /*
 135  *      Whack the dog
 136  */
 137
 138 static void wdt_timer_ping(unsigned long data)
 139 {
 140         /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 141          * we agree to ping the WDT
 142          */
 143         if (time_before(jiffies, next_heartbeat)) {
 144                 /* Ping the WDT */
 145                 spin_lock(&wdt_spinlock);
 146                 writew(0xAAAA, wdtmrctl);
 147                 writew(0x5555, wdtmrctl);
 148                 spin_unlock(&wdt_spinlock);
 149
 150                 /* Re-set the timer interval */
 151                 mod_timer(&timer, jiffies + WDT_INTERVAL);
 152         } else
 153                 printk(KERN_WARNING PFX
 154                         "Heartbeat lost! Will not ping the watchdog\n");
 155 }
 156
 157 /*
 158  *      Utility routines
 159  */
 160
 161 static void wdt_config(int writeval)
 162 {
 163         __u16 dummy;
 164         unsigned long flags;
 165
 166         /* buy some time (ping) */
 167         spin_lock_irqsave(&wdt_spinlock, flags);
 168         dummy = readw(wdtmrctl);        /* ensure write synchronization */
 169         writew(0xAAAA, wdtmrctl);
 170         writew(0x5555, wdtmrctl);
 171         /* unlock WDT = make WDT configuration register writable one time */
 172         writew(0x3333, wdtmrctl);
 173         writew(0xCCCC, wdtmrctl);
 174         /* write WDT configuration register */
 175         writew(writeval, wdtmrctl);
 176         spin_unlock_irqrestore(&wdt_spinlock, flags);
 177 }
 178
 179 static int wdt_startup(void)
 180 {
 181         next_heartbeat = jiffies + (timeout * HZ);
 182
 183         /* Start the timer */
 184         mod_timer(&timer, jiffies + WDT_INTERVAL);
 185
 186         /* Start the watchdog */
 187         wdt_config(WDT_ENB | WDT_WRST_ENB | WDT_EXP_SEL_04);
 188
 189         printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
 190         return 0;
 191 }
 192
 193 static int wdt_turnoff(void)
 194 {
 195         /* Stop the timer */
 196         del_timer(&timer);
 197
 198         /* Stop the watchdog */
 199         wdt_config(0);
 200
 201         printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
 202         return 0;
 203 }
 204
 205 static int wdt_keepalive(void)
 206 {
 207         /* user land ping */
 208         next_heartbeat = jiffies + (timeout * HZ);
 209         return 0;
 210 }
 211
 212 static int wdt_set_heartbeat(int t)
 213 {
 214         if ((t < 1) || (t > 3600))      /* arbitrary upper limit */
 215                 return -EINVAL;
 216
 217         timeout = t;
 218         return 0;
 219 }
 220
 221 /*
 222  *      /dev/watchdog handling
 223  */
 224
 225 static ssize_t fop_write(struct file *file, const char __user *buf,
 226                                                 size_t count, loff_t *ppos)
 227 {
 228         /* See if we got the magic character 'V' and reload the timer */
 229         if (count) {
 230                 if (!nowayout) {
 231                         size_t ofs;
 232
 233                         /* note: just in case someone wrote the magic character
 234                          * five months ago... */
 235                         wdt_expect_close = 0;
 236
 237                         /* now scan */
 238                         for (ofs = 0; ofs != count; ofs++) {
 239                                 char c;
 240                                 if (get_user(c, buf + ofs))
 241                                         return -EFAULT;
 242                                 if (c == 'V')
 243                                         wdt_expect_close = 42;
 244                         }
 245                 }
 246
 247                 /* Well, anyhow someone wrote to us, we should
 248                    return that favour */
 249                 wdt_keepalive();
 250         }
 251         return count;
 252 }
 253
 254 static int fop_open(struct inode *inode, struct file *file)
 255 {
 256         /* Just in case we're already talking to someone... */
 257         if (test_and_set_bit(0, &wdt_is_open))
 258                 return -EBUSY;
 259         if (nowayout)
 260                 __module_get(THIS_MODULE);
 261
 262         /* Good, fire up the show */
 263         wdt_startup();
 264         return nonseekable_open(inode, file);
 265 }
 266
 267 static int fop_close(struct inode *inode, struct file *file)
 268 {
 269         if (wdt_expect_close == 42)
 270                 wdt_turnoff();
 271         else {
 272                 printk(KERN_CRIT PFX
 273                         "Unexpected close, not stopping watchdog!\n");
 274                 wdt_keepalive();
 275         }
 276         clear_bit(0, &wdt_is_open);
 277         wdt_expect_close = 0;
 278         return 0;
 279 }
 280
 281 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 282 {
 283         void __user *argp = (void __user *)arg;
 284         int __user *p = argp;
 285         static const struct watchdog_info ident = {
 286                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
 287                                                         | WDIOF_MAGICCLOSE,
 288                 .firmware_version = 1,
 289                 .identity = "SC520",
 290         };
 291
 292         switch (cmd) {
 293         case WDIOC_GETSUPPORT:
 294                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 295         case WDIOC_GETSTATUS:
 296         case WDIOC_GETBOOTSTATUS:
 297                 return put_user(0, p);
 298         case WDIOC_SETOPTIONS:
 299         {
 300                 int new_options, retval = -EINVAL;
 301
 302                 if (get_user(new_options, p))
 303                         return -EFAULT;
 304
 305                 if (new_options & WDIOS_DISABLECARD) {
 306                         wdt_turnoff();
 307                         retval = 0;
 308                 }
 309
 310                 if (new_options & WDIOS_ENABLECARD) {
 311                         wdt_startup();
 312                         retval = 0;
 313                 }
 314
 315                 return retval;
 316         }
 317         case WDIOC_KEEPALIVE:
 318                 wdt_keepalive();
 319                 return 0;
 320         case WDIOC_SETTIMEOUT:
 321         {
 322                 int new_timeout;
 323
 324                 if (get_user(new_timeout, p))
 325                         return -EFAULT;
 326
 327                 if (wdt_set_heartbeat(new_timeout))
 328                         return -EINVAL;
 329
 330                 wdt_keepalive();
 331                 /* Fall through */
 332         }
 333         case WDIOC_GETTIMEOUT:
 334                 return put_user(timeout, p);
 335         default:
 336                 return -ENOTTY;
 337         }
 338 }
 339
 340 static const struct file_operations wdt_fops = {
 341         .owner          = THIS_MODULE,
 342         .llseek         = no_llseek,
 343         .write          = fop_write,
 344         .open           = fop_open,
 345         .release        = fop_close,
 346         .unlocked_ioctl = fop_ioctl,
 347 };
 348
 349 static struct miscdevice wdt_miscdev = {
 350         .minor  = WATCHDOG_MINOR,
 351         .name   = "watchdog",
 352         .fops   = &wdt_fops,
 353 };
 354
 355 /*
 356  *      Notifier for system down
 357  */
 358
 359 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 360         void *unused)
 361 {
 362         if (code == SYS_DOWN || code == SYS_HALT)
 363                 wdt_turnoff();
 364         return NOTIFY_DONE;
 365 }
 366
 367 /*
 368  *      The WDT needs to learn about soft shutdowns in order to
 369  *      turn the timebomb registers off.
 370  */
 371
 372 static struct notifier_block wdt_notifier = {
 373         .notifier_call = wdt_notify_sys,
 374 };
 375
 376 static void __exit sc520_wdt_unload(void)
 377 {
 378         if (!nowayout)
 379                 wdt_turnoff();
 380
 381         /* Deregister */
 382         misc_deregister(&wdt_miscdev);
 383         unregister_reboot_notifier(&wdt_notifier);
 384         iounmap(wdtmrctl);
 385 }
 386
 387 static int __init sc520_wdt_init(void)
 388 {
 389         int rc = -EBUSY;
 390
 391         /* Check that the timeout value is within it's range ;
 392            if not reset to the default */
 393         if (wdt_set_heartbeat(timeout)) {
 394                 wdt_set_heartbeat(WATCHDOG_TIMEOUT);
 395                 printk(KERN_INFO PFX
 396                     "timeout value must be 1 <= timeout <= 3600, using %d\n",
 397                                                         WATCHDOG_TIMEOUT);
 398         }
 399
 400         wdtmrctl = ioremap(MMCR_BASE + OFFS_WDTMRCTL, 2);
 401         if (!wdtmrctl) {
 402                 printk(KERN_ERR PFX "Unable to remap memory\n");
 403                 rc = -ENOMEM;
 404                 goto err_out_region2;
 405         }
 406
 407         rc = register_reboot_notifier(&wdt_notifier);
 408         if (rc) {
 409                 printk(KERN_ERR PFX
 410                         "cannot register reboot notifier (err=%d)\n", rc);
 411                 goto err_out_ioremap;
 412         }
 413
 414         rc = misc_register(&wdt_miscdev);
 415         if (rc) {
 416                 printk(KERN_ERR PFX
 417                         "cannot register miscdev on minor=%d (err=%d)\n",
 418                                                         WATCHDOG_MINOR, rc);
 419                 goto err_out_notifier;
 420         }
 421
 422         printk(KERN_INFO PFX
 423            "WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n",
 424                                                         timeout, nowayout);
 425
 426         return 0;
 427
 428 err_out_notifier:
 429         unregister_reboot_notifier(&wdt_notifier);
 430 err_out_ioremap:
 431         iounmap(wdtmrctl);
 432 err_out_region2:
 433         return rc;
 434 }
 435
 436 module_init(sc520_wdt_init);
 437 module_exit(sc520_wdt_unload);
 438
 439 MODULE_AUTHOR("Scott and Bill Jennings");
 440 MODULE_DESCRIPTION(
 441         "Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor");
 442 MODULE_LICENSE("GPL");
 443 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);