drivers/watchdog/bfin_wdt.c

   1 /*
   2  * Blackfin On-Chip Watchdog Driver
   3  *  Supports BF53[123]/BF53[467]/BF54[2489]/BF561
   4  *
   5  * Originally based on softdog.c
   6  * Copyright 2006-2007 Analog Devices Inc.
   7  * Copyright 2006-2007 Michele d'Amico
   8  * Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>
   9  *
  10  * Enter bugs at http://blackfin.uclinux.org/
  11  *
  12  * Licensed under the GPL-2 or later.
  13  */
  14
  15 #include <linux/platform_device.h>
  16 #include <linux/module.h>
  17 #include <linux/moduleparam.h>
  18 #include <linux/types.h>
  19 #include <linux/timer.h>
  20 #include <linux/miscdevice.h>
  21 #include <linux/watchdog.h>
  22 #include <linux/fs.h>
  23 #include <linux/notifier.h>
  24 #include <linux/reboot.h>
  25 #include <linux/init.h>
  26 #include <linux/interrupt.h>
  27 #include <linux/uaccess.h>
  28 #include <asm/blackfin.h>
  29
  30 #define stamp(fmt, args...) \
  31         pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args)
  32 #define stampit() stamp("here i am")
  33 #define pr_devinit(fmt, args...) \
  34         ({ static const __devinitconst char __fmt[] = fmt; \
  35         printk(__fmt, ## args); })
  36 #define pr_init(fmt, args...) \
  37         ({ static const __initconst char __fmt[] = fmt; \
  38         printk(__fmt, ## args); })
  39
  40 #define WATCHDOG_NAME "bfin-wdt"
  41 #define PFX WATCHDOG_NAME ": "
  42
  43 /* The BF561 has two watchdogs (one per core), but since Linux
  44  * only runs on core A, we'll just work with that one.
  45  */
  46 #ifdef BF561_FAMILY
  47 # define bfin_read_WDOG_CTL()    bfin_read_WDOGA_CTL()
  48 # define bfin_read_WDOG_CNT()    bfin_read_WDOGA_CNT()
  49 # define bfin_read_WDOG_STAT()   bfin_read_WDOGA_STAT()
  50 # define bfin_write_WDOG_CTL(x)  bfin_write_WDOGA_CTL(x)
  51 # define bfin_write_WDOG_CNT(x)  bfin_write_WDOGA_CNT(x)
  52 # define bfin_write_WDOG_STAT(x) bfin_write_WDOGA_STAT(x)
  53 #endif
  54
  55 /* Bit in SWRST that indicates boot caused by watchdog */
  56 #define SWRST_RESET_WDOG 0x4000
  57
  58 /* Bit in WDOG_CTL that indicates watchdog has expired (WDR0) */
  59 #define WDOG_EXPIRED 0x8000
  60
  61 /* Masks for WDEV field in WDOG_CTL register */
  62 #define ICTL_RESET   0x0
  63 #define ICTL_NMI     0x2
  64 #define ICTL_GPI     0x4
  65 #define ICTL_NONE    0x6
  66 #define ICTL_MASK    0x6
  67
  68 /* Masks for WDEN field in WDOG_CTL register */
  69 #define WDEN_MASK    0x0FF0
  70 #define WDEN_ENABLE  0x0000
  71 #define WDEN_DISABLE 0x0AD0
  72
  73 /* some defaults */
  74 #define WATCHDOG_TIMEOUT 20
  75
  76 static unsigned int timeout = WATCHDOG_TIMEOUT;
  77 static int nowayout = WATCHDOG_NOWAYOUT;
  78 static struct watchdog_info bfin_wdt_info;
  79 static unsigned long open_check;
  80 static char expect_close;
  81 static DEFINE_SPINLOCK(bfin_wdt_spinlock);
  82
  83 /**
  84  *      bfin_wdt_keepalive - Keep the Userspace Watchdog Alive
  85  *
  86  *      The Userspace watchdog got a KeepAlive: schedule the next timeout.
  87  */
  88 static int bfin_wdt_keepalive(void)
  89 {
  90         stampit();
  91         bfin_write_WDOG_STAT(0);
  92         return 0;
  93 }
  94
  95 /**
  96  *      bfin_wdt_stop - Stop the Watchdog
  97  *
  98  *      Stops the on-chip watchdog.
  99  */
 100 static int bfin_wdt_stop(void)
 101 {
 102         stampit();
 103         bfin_write_WDOG_CTL(WDEN_DISABLE);
 104         return 0;
 105 }
 106
 107 /**
 108  *      bfin_wdt_start - Start the Watchdog
 109  *
 110  *      Starts the on-chip watchdog.  Automatically loads WDOG_CNT
 111  *      into WDOG_STAT for us.
 112  */
 113 static int bfin_wdt_start(void)
 114 {
 115         stampit();
 116         bfin_write_WDOG_CTL(WDEN_ENABLE | ICTL_RESET);
 117         return 0;
 118 }
 119
 120 /**
 121  *      bfin_wdt_running - Check Watchdog status
 122  *
 123  *      See if the watchdog is running.
 124  */
 125 static int bfin_wdt_running(void)
 126 {
 127         stampit();
 128         return ((bfin_read_WDOG_CTL() & WDEN_MASK) != WDEN_DISABLE);
 129 }
 130
 131 /**
 132  *      bfin_wdt_set_timeout - Set the Userspace Watchdog timeout
 133  *      @t: new timeout value (in seconds)
 134  *
 135  *      Translate the specified timeout in seconds into System Clock
 136  *      terms which is what the on-chip Watchdog requires.
 137  */
 138 static int bfin_wdt_set_timeout(unsigned long t)
 139 {
 140         u32 cnt;
 141         unsigned long flags;
 142
 143         stampit();
 144
 145         cnt = t * get_sclk();
 146         if (cnt < get_sclk()) {
 147                 printk(KERN_WARNING PFX "timeout value is too large\n");
 148                 return -EINVAL;
 149         }
 150
 151         spin_lock_irqsave(&bfin_wdt_spinlock, flags);
 152         {
 153                 int run = bfin_wdt_running();
 154                 bfin_wdt_stop();
 155                 bfin_write_WDOG_CNT(cnt);
 156                 if (run)
 157                         bfin_wdt_start();
 158         }
 159         spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
 160
 161         timeout = t;
 162
 163         return 0;
 164 }
 165
 166 /**
 167  *      bfin_wdt_open - Open the Device
 168  *      @inode: inode of device
 169  *      @file: file handle of device
 170  *
 171  *      Watchdog device is opened and started.
 172  */
 173 static int bfin_wdt_open(struct inode *inode, struct file *file)
 174 {
 175         stampit();
 176
 177         if (test_and_set_bit(0, &open_check))
 178                 return -EBUSY;
 179
 180         if (nowayout)
 181                 __module_get(THIS_MODULE);
 182
 183         bfin_wdt_keepalive();
 184         bfin_wdt_start();
 185
 186         return nonseekable_open(inode, file);
 187 }
 188
 189 /**
 190  *      bfin_wdt_close - Close the Device
 191  *      @inode: inode of device
 192  *      @file: file handle of device
 193  *
 194  *      Watchdog device is closed and stopped.
 195  */
 196 static int bfin_wdt_release(struct inode *inode, struct file *file)
 197 {
 198         stampit();
 199
 200         if (expect_close == 42)
 201                 bfin_wdt_stop();
 202         else {
 203                 printk(KERN_CRIT PFX
 204                         "Unexpected close, not stopping watchdog!\n");
 205                 bfin_wdt_keepalive();
 206         }
 207         expect_close = 0;
 208         clear_bit(0, &open_check);
 209         return 0;
 210 }
 211
 212 /**
 213  *      bfin_wdt_write - Write to Device
 214  *      @file: file handle of device
 215  *      @buf: buffer to write
 216  *      @count: length of buffer
 217  *      @ppos: offset
 218  *
 219  *      Pings the watchdog on write.
 220  */
 221 static ssize_t bfin_wdt_write(struct file *file, const char __user *data,
 222                                                 size_t len, loff_t *ppos)
 223 {
 224         stampit();
 225
 226         if (len) {
 227                 if (!nowayout) {
 228                         size_t i;
 229
 230                         /* In case it was set long ago */
 231                         expect_close = 0;
 232
 233                         for (i = 0; i != len; i++) {
 234                                 char c;
 235                                 if (get_user(c, data + i))
 236                                         return -EFAULT;
 237                                 if (c == 'V')
 238                                         expect_close = 42;
 239                         }
 240                 }
 241                 bfin_wdt_keepalive();
 242         }
 243
 244         return len;
 245 }
 246
 247 /**
 248  *      bfin_wdt_ioctl - Query Device
 249  *      @file: file handle of device
 250  *      @cmd: watchdog command
 251  *      @arg: argument
 252  *
 253  *      Query basic information from the device or ping it, as outlined by the
 254  *      watchdog API.
 255  */
 256 static long bfin_wdt_ioctl(struct file *file,
 257                                 unsigned int cmd, unsigned long arg)
 258 {
 259         void __user *argp = (void __user *)arg;
 260         int __user *p = argp;
 261
 262         stampit();
 263
 264         switch (cmd) {
 265         case WDIOC_GETSUPPORT:
 266                 if (copy_to_user(argp, &bfin_wdt_info, sizeof(bfin_wdt_info)))
 267                         return -EFAULT;
 268                 else
 269                         return 0;
 270         case WDIOC_GETSTATUS:
 271         case WDIOC_GETBOOTSTATUS:
 272                 return put_user(!!(_bfin_swrst & SWRST_RESET_WDOG), p);
 273         case WDIOC_SETOPTIONS: {
 274                 unsigned long flags;
 275                 int options, ret = -EINVAL;
 276
 277                 if (get_user(options, p))
 278                         return -EFAULT;
 279
 280                 spin_lock_irqsave(&bfin_wdt_spinlock, flags);
 281                 if (options & WDIOS_DISABLECARD) {
 282                         bfin_wdt_stop();
 283                         ret = 0;
 284                 }
 285                 if (options & WDIOS_ENABLECARD) {
 286                         bfin_wdt_start();
 287                         ret = 0;
 288                 }
 289                 spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
 290                 return ret;
 291         }
 292         case WDIOC_KEEPALIVE:
 293                 bfin_wdt_keepalive();
 294                 return 0;
 295         case WDIOC_SETTIMEOUT: {
 296                 int new_timeout;
 297
 298                 if (get_user(new_timeout, p))
 299                         return -EFAULT;
 300                 if (bfin_wdt_set_timeout(new_timeout))
 301                         return -EINVAL;
 302         }
 303         /* Fall */
 304         case WDIOC_GETTIMEOUT:
 305                 return put_user(timeout, p);
 306         default:
 307                 return -ENOTTY;
 308         }
 309 }
 310
 311 /**
 312  *      bfin_wdt_notify_sys - Notifier Handler
 313  *      @this: notifier block
 314  *      @code: notifier event
 315  *      @unused: unused
 316  *
 317  *      Handles specific events, such as turning off the watchdog during a
 318  *      shutdown event.
 319  */
 320 static int bfin_wdt_notify_sys(struct notifier_block *this,
 321                                         unsigned long code, void *unused)
 322 {
 323         stampit();
 324
 325         if (code == SYS_DOWN || code == SYS_HALT)
 326                 bfin_wdt_stop();
 327
 328         return NOTIFY_DONE;
 329 }
 330
 331 #ifdef CONFIG_PM
 332 static int state_before_suspend;
 333
 334 /**
 335  *      bfin_wdt_suspend - suspend the watchdog
 336  *      @pdev: device being suspended
 337  *      @state: requested suspend state
 338  *
 339  *      Remember if the watchdog was running and stop it.
 340  *      TODO: is this even right?  Doesn't seem to be any
 341  *            standard in the watchdog world ...
 342  */
 343 static int bfin_wdt_suspend(struct platform_device *pdev, pm_message_t state)
 344 {
 345         stampit();
 346
 347         state_before_suspend = bfin_wdt_running();
 348         bfin_wdt_stop();
 349
 350         return 0;
 351 }
 352
 353 /**
 354  *      bfin_wdt_resume - resume the watchdog
 355  *      @pdev: device being resumed
 356  *
 357  *      If the watchdog was running, turn it back on.
 358  */
 359 static int bfin_wdt_resume(struct platform_device *pdev)
 360 {
 361         stampit();
 362
 363         if (state_before_suspend) {
 364                 bfin_wdt_set_timeout(timeout);
 365                 bfin_wdt_start();
 366         }
 367
 368         return 0;
 369 }
 370 #else
 371 # define bfin_wdt_suspend NULL
 372 # define bfin_wdt_resume NULL
 373 #endif
 374
 375 static const struct file_operations bfin_wdt_fops = {
 376         .owner          = THIS_MODULE,
 377         .llseek         = no_llseek,
 378         .write          = bfin_wdt_write,
 379         .unlocked_ioctl = bfin_wdt_ioctl,
 380         .open           = bfin_wdt_open,
 381         .release        = bfin_wdt_release,
 382 };
 383
 384 static struct miscdevice bfin_wdt_miscdev = {
 385         .minor    = WATCHDOG_MINOR,
 386         .name     = "watchdog",
 387         .fops     = &bfin_wdt_fops,
 388 };
 389
 390 static struct watchdog_info bfin_wdt_info = {
 391         .identity = "Blackfin Watchdog",
 392         .options  = WDIOF_SETTIMEOUT |
 393                     WDIOF_KEEPALIVEPING |
 394                     WDIOF_MAGICCLOSE,
 395 };
 396
 397 static struct notifier_block bfin_wdt_notifier = {
 398         .notifier_call = bfin_wdt_notify_sys,
 399 };
 400
 401 /**
 402  *      bfin_wdt_probe - Initialize module
 403  *
 404  *      Registers the misc device and notifier handler.  Actual device
 405  *      initialization is handled by bfin_wdt_open().
 406  */
 407 static int __devinit bfin_wdt_probe(struct platform_device *pdev)
 408 {
 409         int ret;
 410
 411         ret = register_reboot_notifier(&bfin_wdt_notifier);
 412         if (ret) {
 413                 pr_devinit(KERN_ERR PFX
 414                         "cannot register reboot notifier (err=%d)\n", ret);
 415                 return ret;
 416         }
 417
 418         ret = misc_register(&bfin_wdt_miscdev);
 419         if (ret) {
 420                 pr_devinit(KERN_ERR PFX
 421                         "cannot register miscdev on minor=%d (err=%d)\n",
 422                                 WATCHDOG_MINOR, ret);
 423                 unregister_reboot_notifier(&bfin_wdt_notifier);
 424                 return ret;
 425         }
 426
 427         pr_devinit(KERN_INFO PFX "initialized: timeout=%d sec (nowayout=%d)\n",
 428                timeout, nowayout);
 429
 430         return 0;
 431 }
 432
 433 /**
 434  *      bfin_wdt_remove - Initialize module
 435  *
 436  *      Unregisters the misc device and notifier handler.  Actual device
 437  *      deinitialization is handled by bfin_wdt_close().
 438  */
 439 static int __devexit bfin_wdt_remove(struct platform_device *pdev)
 440 {
 441         misc_deregister(&bfin_wdt_miscdev);
 442         unregister_reboot_notifier(&bfin_wdt_notifier);
 443         return 0;
 444 }
 445
 446 static struct platform_device *bfin_wdt_device;
 447
 448 static struct platform_driver bfin_wdt_driver = {
 449         .probe     = bfin_wdt_probe,
 450         .remove    = __devexit_p(bfin_wdt_remove),
 451         .suspend   = bfin_wdt_suspend,
 452         .resume    = bfin_wdt_resume,
 453         .driver    = {
 454                 .name  = WATCHDOG_NAME,
 455                 .owner = THIS_MODULE,
 456         },
 457 };
 458
 459 /**
 460  *      bfin_wdt_init - Initialize module
 461  *
 462  *      Checks the module params and registers the platform device & driver.
 463  *      Real work is in the platform probe function.
 464  */
 465 static int __init bfin_wdt_init(void)
 466 {
 467         int ret;
 468
 469         stampit();
 470
 471         /* Check that the timeout value is within range */
 472         if (bfin_wdt_set_timeout(timeout))
 473                 return -EINVAL;
 474
 475         /* Since this is an on-chip device and needs no board-specific
 476          * resources, we'll handle all the platform device stuff here.
 477          */
 478         ret = platform_driver_register(&bfin_wdt_driver);
 479         if (ret) {
 480                 pr_init(KERN_ERR PFX "unable to register driver\n");
 481                 return ret;
 482         }
 483
 484         bfin_wdt_device = platform_device_register_simple(WATCHDOG_NAME,
 485                                                                 -1, NULL, 0);
 486         if (IS_ERR(bfin_wdt_device)) {
 487                 pr_init(KERN_ERR PFX "unable to register device\n");
 488                 platform_driver_unregister(&bfin_wdt_driver);
 489                 return PTR_ERR(bfin_wdt_device);
 490         }
 491
 492         return 0;
 493 }
 494
 495 /**
 496  *      bfin_wdt_exit - Deinitialize module
 497  *
 498  *      Back out the platform device & driver steps.  Real work is in the
 499  *      platform remove function.
 500  */
 501 static void __exit bfin_wdt_exit(void)
 502 {
 503         platform_device_unregister(bfin_wdt_device);
 504         platform_driver_unregister(&bfin_wdt_driver);
 505 }
 506
 507 module_init(bfin_wdt_init);
 508 module_exit(bfin_wdt_exit);
 509
 510 MODULE_AUTHOR("Michele d'Amico, Mike Frysinger <vapier@gentoo.org>");
 511 MODULE_DESCRIPTION("Blackfin Watchdog Device Driver");
 512 MODULE_LICENSE("GPL");
 513 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 514
 515 module_param(timeout, uint, 0);
 516 MODULE_PARM_DESC(timeout,
 517         "Watchdog timeout in seconds. (1<=timeout<=((2^32)/SCLK), default="
 518                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 519
 520 module_param(nowayout, int, 0);
 521 MODULE_PARM_DESC(nowayout,
 522         "Watchdog cannot be stopped once started (default="
 523                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");