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 <asm/blackfin.h>
  28 #include <asm/uaccess.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) bfin_wdt_start();
 152         }
 153         spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
 154
 155         timeout = t;
 156
 157         return 0;
 158 }
 159
 160 /**
 161  *      bfin_wdt_open - Open the Device
 162  *      @inode: inode of device
 163  *      @file: file handle of device
 164  *
 165  *      Watchdog device is opened and started.
 166  */
 167 static int bfin_wdt_open(struct inode *inode, struct file *file)
 168 {
 169         stampit();
 170
 171         if (test_and_set_bit(0, &open_check))
 172                 return -EBUSY;
 173
 174         if (nowayout)
 175                 __module_get(THIS_MODULE);
 176
 177         bfin_wdt_keepalive();
 178         bfin_wdt_start();
 179
 180         return nonseekable_open(inode, file);
 181 }
 182
 183 /**
 184  *      bfin_wdt_close - Close the Device
 185  *      @inode: inode of device
 186  *      @file: file handle of device
 187  *
 188  *      Watchdog device is closed and stopped.
 189  */
 190 static int bfin_wdt_release(struct inode *inode, struct file *file)
 191 {
 192         stampit();
 193
 194         if (expect_close == 42) {
 195                 bfin_wdt_stop();
 196         } else {
 197                 printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
 198                 bfin_wdt_keepalive();
 199         }
 200
 201         expect_close = 0;
 202         clear_bit(0, &open_check);
 203
 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  *      @inode: inode of device
 245  *      @file: file handle of device
 246  *      @cmd: watchdog command
 247  *      @arg: argument
 248  *
 249  *      Query basic information from the device or ping it, as outlined by the
 250  *      watchdog API.
 251  */
 252 static int bfin_wdt_ioctl(struct inode *inode, struct file *file,
 253                           unsigned int cmd, unsigned long arg)
 254 {
 255         void __user *argp = (void __user *)arg;
 256         int __user *p = argp;
 257
 258         stampit();
 259
 260         switch (cmd) {
 261                 default:
 262                         return -ENOTTY;
 263
 264                 case WDIOC_GETSUPPORT:
 265                         if (copy_to_user(argp, &bfin_wdt_info, sizeof(bfin_wdt_info)))
 266                                 return -EFAULT;
 267                         else
 268                                 return 0;
 269
 270                 case WDIOC_GETSTATUS:
 271                 case WDIOC_GETBOOTSTATUS:
 272                         return put_user(!!(_bfin_swrst & SWRST_RESET_WDOG), p);
 273
 274                 case WDIOC_KEEPALIVE:
 275                         bfin_wdt_keepalive();
 276                         return 0;
 277
 278                 case WDIOC_SETTIMEOUT: {
 279                         int new_timeout;
 280
 281                         if (get_user(new_timeout, p))
 282                                 return -EFAULT;
 283
 284                         if (bfin_wdt_set_timeout(new_timeout))
 285                                 return -EINVAL;
 286                 }
 287                         /* Fall */
 288                 case WDIOC_GETTIMEOUT:
 289                         return put_user(timeout, p);
 290
 291                 case WDIOC_SETOPTIONS: {
 292                         unsigned long flags;
 293                         int options, ret = -EINVAL;
 294
 295                         if (get_user(options, p))
 296                                 return -EFAULT;
 297
 298                         spin_lock_irqsave(&bfin_wdt_spinlock, flags);
 299
 300                         if (options & WDIOS_DISABLECARD) {
 301                                 bfin_wdt_stop();
 302                                 ret = 0;
 303                         }
 304
 305                         if (options & WDIOS_ENABLECARD) {
 306                                 bfin_wdt_start();
 307                                 ret = 0;
 308                         }
 309
 310                         spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
 311
 312                         return ret;
 313                 }
 314         }
 315 }
 316
 317 /**
 318  *      bfin_wdt_notify_sys - Notifier Handler
 319  *      @this: notifier block
 320  *      @code: notifier event
 321  *      @unused: unused
 322  *
 323  *      Handles specific events, such as turning off the watchdog during a
 324  *      shutdown event.
 325  */
 326 static int bfin_wdt_notify_sys(struct notifier_block *this, unsigned long code,
 327                                void *unused)
 328 {
 329         stampit();
 330
 331         if (code == SYS_DOWN || code == SYS_HALT)
 332                 bfin_wdt_stop();
 333
 334         return NOTIFY_DONE;
 335 }
 336
 337 #ifdef CONFIG_PM
 338 static int state_before_suspend;
 339
 340 /**
 341  *      bfin_wdt_suspend - suspend the watchdog
 342  *      @pdev: device being suspended
 343  *      @state: requested suspend state
 344  *
 345  *      Remember if the watchdog was running and stop it.
 346  *      TODO: is this even right?  Doesn't seem to be any
 347  *            standard in the watchdog world ...
 348  */
 349 static int bfin_wdt_suspend(struct platform_device *pdev, pm_message_t state)
 350 {
 351         stampit();
 352
 353         state_before_suspend = bfin_wdt_running();
 354         bfin_wdt_stop();
 355
 356         return 0;
 357 }
 358
 359 /**
 360  *      bfin_wdt_resume - resume the watchdog
 361  *      @pdev: device being resumed
 362  *
 363  *      If the watchdog was running, turn it back on.
 364  */
 365 static int bfin_wdt_resume(struct platform_device *pdev)
 366 {
 367         stampit();
 368
 369         if (state_before_suspend) {
 370                 bfin_wdt_set_timeout(timeout);
 371                 bfin_wdt_start();
 372         }
 373
 374         return 0;
 375 }
 376 #else
 377 # define bfin_wdt_suspend NULL
 378 # define bfin_wdt_resume NULL
 379 #endif
 380
 381 static const struct file_operations bfin_wdt_fops = {
 382         .owner    = THIS_MODULE,
 383         .llseek   = no_llseek,
 384         .write    = bfin_wdt_write,
 385         .ioctl    = bfin_wdt_ioctl,
 386         .open     = bfin_wdt_open,
 387         .release  = bfin_wdt_release,
 388 };
 389
 390 static struct miscdevice bfin_wdt_miscdev = {
 391         .minor    = WATCHDOG_MINOR,
 392         .name     = "watchdog",
 393         .fops     = &bfin_wdt_fops,
 394 };
 395
 396 static struct watchdog_info bfin_wdt_info = {
 397         .identity = "Blackfin Watchdog",
 398         .options  = WDIOF_SETTIMEOUT |
 399                     WDIOF_KEEPALIVEPING |
 400                     WDIOF_MAGICCLOSE,
 401 };
 402
 403 static struct notifier_block bfin_wdt_notifier = {
 404         .notifier_call = bfin_wdt_notify_sys,
 405 };
 406
 407 /**
 408  *      bfin_wdt_probe - Initialize module
 409  *
 410  *      Registers the misc device and notifier handler.  Actual device
 411  *      initialization is handled by bfin_wdt_open().
 412  */
 413 static int __devinit bfin_wdt_probe(struct platform_device *pdev)
 414 {
 415         int ret;
 416
 417         ret = register_reboot_notifier(&bfin_wdt_notifier);
 418         if (ret) {
 419                 pr_devinit(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n", ret);
 420                 return ret;
 421         }
 422
 423         ret = misc_register(&bfin_wdt_miscdev);
 424         if (ret) {
 425                 pr_devinit(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
 426                        WATCHDOG_MINOR, ret);
 427                 unregister_reboot_notifier(&bfin_wdt_notifier);
 428                 return ret;
 429         }
 430
 431         pr_devinit(KERN_INFO PFX "initialized: timeout=%d sec (nowayout=%d)\n",
 432                timeout, nowayout);
 433
 434         return 0;
 435 }
 436
 437 /**
 438  *      bfin_wdt_remove - Initialize module
 439  *
 440  *      Unregisters the misc device and notifier handler.  Actual device
 441  *      deinitialization is handled by bfin_wdt_close().
 442  */
 443 static int __devexit bfin_wdt_remove(struct platform_device *pdev)
 444 {
 445         misc_deregister(&bfin_wdt_miscdev);
 446         unregister_reboot_notifier(&bfin_wdt_notifier);
 447         return 0;
 448 }
 449
 450 static struct platform_device *bfin_wdt_device;
 451
 452 static struct platform_driver bfin_wdt_driver = {
 453         .probe     = bfin_wdt_probe,
 454         .remove    = __devexit_p(bfin_wdt_remove),
 455         .suspend   = bfin_wdt_suspend,
 456         .resume    = bfin_wdt_resume,
 457         .driver    = {
 458                 .name  = WATCHDOG_NAME,
 459                 .owner = THIS_MODULE,
 460         },
 461 };
 462
 463 /**
 464  *      bfin_wdt_init - Initialize module
 465  *
 466  *      Checks the module params and registers the platform device & driver.
 467  *      Real work is in the platform probe function.
 468  */
 469 static int __init bfin_wdt_init(void)
 470 {
 471         int ret;
 472
 473         stampit();
 474
 475         /* Check that the timeout value is within range */
 476         if (bfin_wdt_set_timeout(timeout))
 477                 return -EINVAL;
 478
 479         /* Since this is an on-chip device and needs no board-specific
 480          * resources, we'll handle all the platform device stuff here.
 481          */
 482         ret = platform_driver_register(&bfin_wdt_driver);
 483         if (ret) {
 484                 pr_init(KERN_ERR PFX "unable to register driver\n");
 485                 return ret;
 486         }
 487
 488         bfin_wdt_device = platform_device_register_simple(WATCHDOG_NAME, -1, NULL, 0);
 489         if (IS_ERR(bfin_wdt_device)) {
 490                 pr_init(KERN_ERR PFX "unable to register device\n");
 491                 platform_driver_unregister(&bfin_wdt_driver);
 492                 return PTR_ERR(bfin_wdt_device);
 493         }
 494
 495         return 0;
 496 }
 497
 498 /**
 499  *      bfin_wdt_exit - Deinitialize module
 500  *
 501  *      Back out the platform device & driver steps.  Real work is in the
 502  *      platform remove function.
 503  */
 504 static void __exit bfin_wdt_exit(void)
 505 {
 506         platform_device_unregister(bfin_wdt_device);
 507         platform_driver_unregister(&bfin_wdt_driver);
 508 }
 509
 510 module_init(bfin_wdt_init);
 511 module_exit(bfin_wdt_exit);
 512
 513 MODULE_AUTHOR("Michele d'Amico, Mike Frysinger <vapier@gentoo.org>");
 514 MODULE_DESCRIPTION("Blackfin Watchdog Device Driver");
 515 MODULE_LICENSE("GPL");
 516 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 517
 518 module_param(timeout, uint, 0);
 519 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=((2^32)/SCLK), default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 520
 521 module_param(nowayout, int, 0);
 522 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");