drivers/watchdog/bfin_wdt.c

   1 /*
   2  * Blackfin On-Chip Watchdog Driver
   3  *
   4  * Originally based on softdog.c
   5  * Copyright 2006-2010 Analog Devices Inc.
   6  * Copyright 2006-2007 Michele d'Amico
   7  * Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>
   8  *
   9  * Enter bugs at http://blackfin.uclinux.org/
  10  *
  11  * Licensed under the GPL-2 or later.
  12  */
  13
  14 #include <linux/platform_device.h>
  15 #include <linux/module.h>
  16 #include <linux/moduleparam.h>
  17 #include <linux/types.h>
  18 #include <linux/timer.h>
  19 #include <linux/miscdevice.h>
  20 #include <linux/watchdog.h>
  21 #include <linux/fs.h>
  22 #include <linux/init.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/uaccess.h>
  25 #include <asm/blackfin.h>
  26
  27 #define stamp(fmt, args...) \
  28         pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args)
  29 #define stampit() stamp("here i am")
  30 #define pr_devinit(fmt, args...) \
  31         ({ static const __devinitconst char __fmt[] = fmt; \
  32         printk(__fmt, ## args); })
  33 #define pr_init(fmt, args...) \
  34         ({ static const __initconst char __fmt[] = fmt; \
  35         printk(__fmt, ## args); })
  36
  37 #define WATCHDOG_NAME "bfin-wdt"
  38 #define PFX WATCHDOG_NAME ": "
  39
  40 /* The BF561 has two watchdogs (one per core), but since Linux
  41  * only runs on core A, we'll just work with that one.
  42  */
  43 #ifdef BF561_FAMILY
  44 # define bfin_read_WDOG_CTL()    bfin_read_WDOGA_CTL()
  45 # define bfin_read_WDOG_CNT()    bfin_read_WDOGA_CNT()
  46 # define bfin_read_WDOG_STAT()   bfin_read_WDOGA_STAT()
  47 # define bfin_write_WDOG_CTL(x)  bfin_write_WDOGA_CTL(x)
  48 # define bfin_write_WDOG_CNT(x)  bfin_write_WDOGA_CNT(x)
  49 # define bfin_write_WDOG_STAT(x) bfin_write_WDOGA_STAT(x)
  50 #endif
  51
  52 /* Bit in SWRST that indicates boot caused by watchdog */
  53 #define SWRST_RESET_WDOG 0x4000
  54
  55 /* Bit in WDOG_CTL that indicates watchdog has expired (WDR0) */
  56 #define WDOG_EXPIRED 0x8000
  57
  58 /* Masks for WDEV field in WDOG_CTL register */
  59 #define ICTL_RESET   0x0
  60 #define ICTL_NMI     0x2
  61 #define ICTL_GPI     0x4
  62 #define ICTL_NONE    0x6
  63 #define ICTL_MASK    0x6
  64
  65 /* Masks for WDEN field in WDOG_CTL register */
  66 #define WDEN_MASK    0x0FF0
  67 #define WDEN_ENABLE  0x0000
  68 #define WDEN_DISABLE 0x0AD0
  69
  70 /* some defaults */
  71 #define WATCHDOG_TIMEOUT 20
  72
  73 static unsigned int timeout = WATCHDOG_TIMEOUT;
  74 static int nowayout = WATCHDOG_NOWAYOUT;
  75 static const struct watchdog_info bfin_wdt_info;
  76 static unsigned long open_check;
  77 static char expect_close;
  78 static DEFINE_SPINLOCK(bfin_wdt_spinlock);
  79
  80 /**
  81  *      bfin_wdt_keepalive - Keep the Userspace Watchdog Alive
  82  *
  83  *      The Userspace watchdog got a KeepAlive: schedule the next timeout.
  84  */
  85 static int bfin_wdt_keepalive(void)
  86 {
  87         stampit();
  88         bfin_write_WDOG_STAT(0);
  89         return 0;
  90 }
  91
  92 /**
  93  *      bfin_wdt_stop - Stop the Watchdog
  94  *
  95  *      Stops the on-chip watchdog.
  96  */
  97 static int bfin_wdt_stop(void)
  98 {
  99         stampit();
 100         bfin_write_WDOG_CTL(WDEN_DISABLE);
 101         return 0;
 102 }
 103
 104 /**
 105  *      bfin_wdt_start - Start the Watchdog
 106  *
 107  *      Starts the on-chip watchdog.  Automatically loads WDOG_CNT
 108  *      into WDOG_STAT for us.
 109  */
 110 static int bfin_wdt_start(void)
 111 {
 112         stampit();
 113         bfin_write_WDOG_CTL(WDEN_ENABLE | ICTL_RESET);
 114         return 0;
 115 }
 116
 117 /**
 118  *      bfin_wdt_running - Check Watchdog status
 119  *
 120  *      See if the watchdog is running.
 121  */
 122 static int bfin_wdt_running(void)
 123 {
 124         stampit();
 125         return ((bfin_read_WDOG_CTL() & WDEN_MASK) != WDEN_DISABLE);
 126 }
 127
 128 /**
 129  *      bfin_wdt_set_timeout - Set the Userspace Watchdog timeout
 130  *      @t: new timeout value (in seconds)
 131  *
 132  *      Translate the specified timeout in seconds into System Clock
 133  *      terms which is what the on-chip Watchdog requires.
 134  */
 135 static int bfin_wdt_set_timeout(unsigned long t)
 136 {
 137         u32 cnt, max_t, sclk;
 138         unsigned long flags;
 139
 140         sclk = get_sclk();
 141         max_t = -1 / sclk;
 142         cnt = t * sclk;
 143         stamp("maxtimeout=%us newtimeout=%lus (cnt=%#x)", max_t, t, cnt);
 144
 145         if (t > max_t) {
 146                 printk(KERN_WARNING PFX "timeout value is too large\n");
 147                 return -EINVAL;
 148         }
 149
 150         spin_lock_irqsave(&bfin_wdt_spinlock, flags);
 151         {
 152                 int run = bfin_wdt_running();
 153                 bfin_wdt_stop();
 154                 bfin_write_WDOG_CNT(cnt);
 155                 if (run)
 156                         bfin_wdt_start();
 157         }
 158         spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
 159
 160         timeout = t;
 161
 162         return 0;
 163 }
 164
 165 /**
 166  *      bfin_wdt_open - Open the Device
 167  *      @inode: inode of device
 168  *      @file: file handle of device
 169  *
 170  *      Watchdog device is opened and started.
 171  */
 172 static int bfin_wdt_open(struct inode *inode, struct file *file)
 173 {
 174         stampit();
 175
 176         if (test_and_set_bit(0, &open_check))
 177                 return -EBUSY;
 178
 179         if (nowayout)
 180                 __module_get(THIS_MODULE);
 181
 182         bfin_wdt_keepalive();
 183         bfin_wdt_start();
 184
 185         return nonseekable_open(inode, file);
 186 }
 187
 188 /**
 189  *      bfin_wdt_close - Close the Device
 190  *      @inode: inode of device
 191  *      @file: file handle of device
 192  *
 193  *      Watchdog device is closed and stopped.
 194  */
 195 static int bfin_wdt_release(struct inode *inode, struct file *file)
 196 {
 197         stampit();
 198
 199         if (expect_close == 42)
 200                 bfin_wdt_stop();
 201         else {
 202                 printk(KERN_CRIT PFX
 203                         "Unexpected close, not stopping watchdog!\n");
 204                 bfin_wdt_keepalive();
 205         }
 206         expect_close = 0;
 207         clear_bit(0, &open_check);
 208         return 0;
 209 }
 210
 211 /**
 212  *      bfin_wdt_write - Write to Device
 213  *      @file: file handle of device
 214  *      @buf: buffer to write
 215  *      @count: length of buffer
 216  *      @ppos: offset
 217  *
 218  *      Pings the watchdog on write.
 219  */
 220 static ssize_t bfin_wdt_write(struct file *file, const char __user *data,
 221                                                 size_t len, loff_t *ppos)
 222 {
 223         stampit();
 224
 225         if (len) {
 226                 if (!nowayout) {
 227                         size_t i;
 228
 229                         /* In case it was set long ago */
 230                         expect_close = 0;
 231
 232                         for (i = 0; i != len; i++) {
 233                                 char c;
 234                                 if (get_user(c, data + i))
 235                                         return -EFAULT;
 236                                 if (c == 'V')
 237                                         expect_close = 42;
 238                         }
 239                 }
 240                 bfin_wdt_keepalive();
 241         }
 242
 243         return len;
 244 }
 245
 246 /**
 247  *      bfin_wdt_ioctl - Query Device
 248  *      @file: file handle of device
 249  *      @cmd: watchdog command
 250  *      @arg: argument
 251  *
 252  *      Query basic information from the device or ping it, as outlined by the
 253  *      watchdog API.
 254  */
 255 static long bfin_wdt_ioctl(struct file *file,
 256                                 unsigned int cmd, unsigned long arg)
 257 {
 258         void __user *argp = (void __user *)arg;
 259         int __user *p = argp;
 260
 261         stampit();
 262
 263         switch (cmd) {
 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         case WDIOC_GETSTATUS:
 270         case WDIOC_GETBOOTSTATUS:
 271                 return put_user(!!(_bfin_swrst & SWRST_RESET_WDOG), p);
 272         case WDIOC_SETOPTIONS: {
 273                 unsigned long flags;
 274                 int options, ret = -EINVAL;
 275
 276                 if (get_user(options, p))
 277                         return -EFAULT;
 278
 279                 spin_lock_irqsave(&bfin_wdt_spinlock, flags);
 280                 if (options & WDIOS_DISABLECARD) {
 281                         bfin_wdt_stop();
 282                         ret = 0;
 283                 }
 284                 if (options & WDIOS_ENABLECARD) {
 285                         bfin_wdt_start();
 286                         ret = 0;
 287                 }
 288                 spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
 289                 return ret;
 290         }
 291         case WDIOC_KEEPALIVE:
 292                 bfin_wdt_keepalive();
 293                 return 0;
 294         case WDIOC_SETTIMEOUT: {
 295                 int new_timeout;
 296
 297                 if (get_user(new_timeout, p))
 298                         return -EFAULT;
 299                 if (bfin_wdt_set_timeout(new_timeout))
 300                         return -EINVAL;
 301         }
 302         /* Fall */
 303         case WDIOC_GETTIMEOUT:
 304                 return put_user(timeout, p);
 305         default:
 306                 return -ENOTTY;
 307         }
 308 }
 309
 310 #ifdef CONFIG_PM
 311 static int state_before_suspend;
 312
 313 /**
 314  *      bfin_wdt_suspend - suspend the watchdog
 315  *      @pdev: device being suspended
 316  *      @state: requested suspend state
 317  *
 318  *      Remember if the watchdog was running and stop it.
 319  *      TODO: is this even right?  Doesn't seem to be any
 320  *            standard in the watchdog world ...
 321  */
 322 static int bfin_wdt_suspend(struct platform_device *pdev, pm_message_t state)
 323 {
 324         stampit();
 325
 326         state_before_suspend = bfin_wdt_running();
 327         bfin_wdt_stop();
 328
 329         return 0;
 330 }
 331
 332 /**
 333  *      bfin_wdt_resume - resume the watchdog
 334  *      @pdev: device being resumed
 335  *
 336  *      If the watchdog was running, turn it back on.
 337  */
 338 static int bfin_wdt_resume(struct platform_device *pdev)
 339 {
 340         stampit();
 341
 342         if (state_before_suspend) {
 343                 bfin_wdt_set_timeout(timeout);
 344                 bfin_wdt_start();
 345         }
 346
 347         return 0;
 348 }
 349 #else
 350 # define bfin_wdt_suspend NULL
 351 # define bfin_wdt_resume NULL
 352 #endif
 353
 354 static const struct file_operations bfin_wdt_fops = {
 355         .owner          = THIS_MODULE,
 356         .llseek         = no_llseek,
 357         .write          = bfin_wdt_write,
 358         .unlocked_ioctl = bfin_wdt_ioctl,
 359         .open           = bfin_wdt_open,
 360         .release        = bfin_wdt_release,
 361 };
 362
 363 static struct miscdevice bfin_wdt_miscdev = {
 364         .minor    = WATCHDOG_MINOR,
 365         .name     = "watchdog",
 366         .fops     = &bfin_wdt_fops,
 367 };
 368
 369 static const struct watchdog_info bfin_wdt_info = {
 370         .identity = "Blackfin Watchdog",
 371         .options  = WDIOF_SETTIMEOUT |
 372                     WDIOF_KEEPALIVEPING |
 373                     WDIOF_MAGICCLOSE,
 374 };
 375
 376 /**
 377  *      bfin_wdt_probe - Initialize module
 378  *
 379  *      Registers the misc device.  Actual device
 380  *      initialization is handled by bfin_wdt_open().
 381  */
 382 static int __devinit bfin_wdt_probe(struct platform_device *pdev)
 383 {
 384         int ret;
 385
 386         ret = misc_register(&bfin_wdt_miscdev);
 387         if (ret) {
 388                 pr_devinit(KERN_ERR PFX
 389                         "cannot register miscdev on minor=%d (err=%d)\n",
 390                                 WATCHDOG_MINOR, ret);
 391                 return ret;
 392         }
 393
 394         pr_devinit(KERN_INFO PFX "initialized: timeout=%d sec (nowayout=%d)\n",
 395                timeout, nowayout);
 396
 397         return 0;
 398 }
 399
 400 /**
 401  *      bfin_wdt_remove - Initialize module
 402  *
 403  *      Unregisters the misc device.  Actual device
 404  *      deinitialization is handled by bfin_wdt_close().
 405  */
 406 static int __devexit bfin_wdt_remove(struct platform_device *pdev)
 407 {
 408         misc_deregister(&bfin_wdt_miscdev);
 409         return 0;
 410 }
 411
 412 /**
 413  *      bfin_wdt_shutdown - Soft Shutdown Handler
 414  *
 415  *      Handles the soft shutdown event.
 416  */
 417 static void bfin_wdt_shutdown(struct platform_device *pdev)
 418 {
 419         stampit();
 420
 421         bfin_wdt_stop();
 422 }
 423
 424 static struct platform_device *bfin_wdt_device;
 425
 426 static struct platform_driver bfin_wdt_driver = {
 427         .probe     = bfin_wdt_probe,
 428         .remove    = __devexit_p(bfin_wdt_remove),
 429         .shutdown  = bfin_wdt_shutdown,
 430         .suspend   = bfin_wdt_suspend,
 431         .resume    = bfin_wdt_resume,
 432         .driver    = {
 433                 .name  = WATCHDOG_NAME,
 434                 .owner = THIS_MODULE,
 435         },
 436 };
 437
 438 /**
 439  *      bfin_wdt_init - Initialize module
 440  *
 441  *      Checks the module params and registers the platform device & driver.
 442  *      Real work is in the platform probe function.
 443  */
 444 static int __init bfin_wdt_init(void)
 445 {
 446         int ret;
 447
 448         stampit();
 449
 450         /* Check that the timeout value is within range */
 451         if (bfin_wdt_set_timeout(timeout))
 452                 return -EINVAL;
 453
 454         /* Since this is an on-chip device and needs no board-specific
 455          * resources, we'll handle all the platform device stuff here.
 456          */
 457         ret = platform_driver_register(&bfin_wdt_driver);
 458         if (ret) {
 459                 pr_init(KERN_ERR PFX "unable to register driver\n");
 460                 return ret;
 461         }
 462
 463         bfin_wdt_device = platform_device_register_simple(WATCHDOG_NAME,
 464                                                                 -1, NULL, 0);
 465         if (IS_ERR(bfin_wdt_device)) {
 466                 pr_init(KERN_ERR PFX "unable to register device\n");
 467                 platform_driver_unregister(&bfin_wdt_driver);
 468                 return PTR_ERR(bfin_wdt_device);
 469         }
 470
 471         return 0;
 472 }
 473
 474 /**
 475  *      bfin_wdt_exit - Deinitialize module
 476  *
 477  *      Back out the platform device & driver steps.  Real work is in the
 478  *      platform remove function.
 479  */
 480 static void __exit bfin_wdt_exit(void)
 481 {
 482         platform_device_unregister(bfin_wdt_device);
 483         platform_driver_unregister(&bfin_wdt_driver);
 484 }
 485
 486 module_init(bfin_wdt_init);
 487 module_exit(bfin_wdt_exit);
 488
 489 MODULE_AUTHOR("Michele d'Amico, Mike Frysinger <vapier@gentoo.org>");
 490 MODULE_DESCRIPTION("Blackfin Watchdog Device Driver");
 491 MODULE_LICENSE("GPL");
 492 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 493
 494 module_param(timeout, uint, 0);
 495 MODULE_PARM_DESC(timeout,
 496         "Watchdog timeout in seconds. (1<=timeout<=((2^32)/SCLK), default="
 497                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 498
 499 module_param(nowayout, int, 0);
 500 MODULE_PARM_DESC(nowayout,
 501         "Watchdog cannot be stopped once started (default="
 502                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");