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