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