drivers/watchdog/mpcore_wdt.c

   1 /*
   2  *      Watchdog driver for the mpcore watchdog timer
   3  *
   4  *      (c) Copyright 2004 ARM Limited
   5  *
   6  *      Based on the SoftDog driver:
   7  *      (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
   8  *                                              All Rights Reserved.
   9  *
  10  *      This program is free software; you can redistribute it and/or
  11  *      modify it under the terms of the GNU General Public License
  12  *      as published by the Free Software Foundation; either version
  13  *      2 of the License, or (at your option) any later version.
  14  *
  15  *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  16  *      warranty for any of this software. This material is provided
  17  *      "AS-IS" and at no charge.
  18  *
  19  *      (c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
  20  *
  21  */
  22 #include <linux/module.h>
  23 #include <linux/moduleparam.h>
  24 #include <linux/types.h>
  25 #include <linux/miscdevice.h>
  26 #include <linux/watchdog.h>
  27 #include <linux/fs.h>
  28 #include <linux/reboot.h>
  29 #include <linux/init.h>
  30 #include <linux/interrupt.h>
  31 #include <linux/platform_device.h>
  32 #include <linux/uaccess.h>
  33
  34 #include <asm/hardware/arm_twd.h>
  35
  36 struct mpcore_wdt {
  37         unsigned long   timer_alive;
  38         struct device   *dev;
  39         void __iomem    *base;
  40         int             irq;
  41         unsigned int    perturb;
  42         char            expect_close;
  43 };
  44
  45 static struct platform_device *mpcore_wdt_dev;
  46 extern unsigned int mpcore_timer_rate;
  47
  48 #define TIMER_MARGIN    60
  49 static int mpcore_margin = TIMER_MARGIN;
  50 module_param(mpcore_margin, int, 0);
  51 MODULE_PARM_DESC(mpcore_margin,
  52         "MPcore timer margin in seconds. (0 < mpcore_margin < 65536, default="
  53                                 __MODULE_STRING(TIMER_MARGIN) ")");
  54
  55 static int nowayout = WATCHDOG_NOWAYOUT;
  56 module_param(nowayout, int, 0);
  57 MODULE_PARM_DESC(nowayout,
  58         "Watchdog cannot be stopped once started (default="
  59                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  60
  61 #define ONLY_TESTING    0
  62 static int mpcore_noboot = ONLY_TESTING;
  63 module_param(mpcore_noboot, int, 0);
  64 MODULE_PARM_DESC(mpcore_noboot, "MPcore watchdog action, set to 1 to ignore reboots, 0 to reboot (default=" __MODULE_STRING(ONLY_TESTING) ")");
  65
  66 /*
  67  *      This is the interrupt handler.  Note that we only use this
  68  *      in testing mode, so don't actually do a reboot here.
  69  */
  70 static irqreturn_t mpcore_wdt_fire(int irq, void *arg)
  71 {
  72         struct mpcore_wdt *wdt = arg;
  73
  74         /* Check it really was our interrupt */
  75         if (readl(wdt->base + TWD_WDOG_INTSTAT)) {
  76                 dev_printk(KERN_CRIT, wdt->dev,
  77                                         "Triggered - Reboot ignored.\n");
  78                 /* Clear the interrupt on the watchdog */
  79                 writel(1, wdt->base + TWD_WDOG_INTSTAT);
  80                 return IRQ_HANDLED;
  81         }
  82         return IRQ_NONE;
  83 }
  84
  85 /*
  86  *      mpcore_wdt_keepalive - reload the timer
  87  *
  88  *      Note that the spec says a DIFFERENT value must be written to the reload
  89  *      register each time.  The "perturb" variable deals with this by adding 1
  90  *      to the count every other time the function is called.
  91  */
  92 static void mpcore_wdt_keepalive(struct mpcore_wdt *wdt)
  93 {
  94         unsigned int count;
  95
  96         /* Assume prescale is set to 256 */
  97         count = (mpcore_timer_rate / 256) * mpcore_margin;
  98
  99         /* Reload the counter */
 100         spin_lock(&wdt_lock);
 101         writel(count + wdt->perturb, wdt->base + TWD_WDOG_LOAD);
 102         wdt->perturb = wdt->perturb ? 0 : 1;
 103         spin_unlock(&wdt_lock);
 104 }
 105
 106 static void mpcore_wdt_stop(struct mpcore_wdt *wdt)
 107 {
 108         spin_lock(&wdt_lock);
 109         writel(0x12345678, wdt->base + TWD_WDOG_DISABLE);
 110         writel(0x87654321, wdt->base + TWD_WDOG_DISABLE);
 111         writel(0x0, wdt->base + TWD_WDOG_CONTROL);
 112         spin_unlock(&wdt_lock);
 113 }
 114
 115 static void mpcore_wdt_start(struct mpcore_wdt *wdt)
 116 {
 117         dev_printk(KERN_INFO, wdt->dev, "enabling watchdog.\n");
 118
 119         spin_lock(&wdt_lock);
 120         /* This loads the count register but does NOT start the count yet */
 121         mpcore_wdt_keepalive(wdt);
 122
 123         if (mpcore_noboot) {
 124                 /* Enable watchdog - prescale=256, watchdog mode=0, enable=1 */
 125                 writel(0x0000FF01, wdt->base + TWD_WDOG_CONTROL);
 126         } else {
 127                 /* Enable watchdog - prescale=256, watchdog mode=1, enable=1 */
 128                 writel(0x0000FF09, wdt->base + TWD_WDOG_CONTROL);
 129         }
 130         spin_unlock(&wdt_lock);
 131 }
 132
 133 static int mpcore_wdt_set_heartbeat(int t)
 134 {
 135         if (t < 0x0001 || t > 0xFFFF)
 136                 return -EINVAL;
 137
 138         mpcore_margin = t;
 139         return 0;
 140 }
 141
 142 /*
 143  *      /dev/watchdog handling
 144  */
 145 static int mpcore_wdt_open(struct inode *inode, struct file *file)
 146 {
 147         struct mpcore_wdt *wdt = platform_get_drvdata(mpcore_wdt_dev);
 148
 149         if (test_and_set_bit(0, &wdt->timer_alive))
 150                 return -EBUSY;
 151
 152         if (nowayout)
 153                 __module_get(THIS_MODULE);
 154
 155         file->private_data = wdt;
 156
 157         /*
 158          *      Activate timer
 159          */
 160         mpcore_wdt_start(wdt);
 161
 162         return nonseekable_open(inode, file);
 163 }
 164
 165 static int mpcore_wdt_release(struct inode *inode, struct file *file)
 166 {
 167         struct mpcore_wdt *wdt = file->private_data;
 168
 169         /*
 170          *      Shut off the timer.
 171          *      Lock it in if it's a module and we set nowayout
 172          */
 173         if (wdt->expect_close == 42)
 174                 mpcore_wdt_stop(wdt);
 175         else {
 176                 dev_printk(KERN_CRIT, wdt->dev,
 177                                 "unexpected close, not stopping watchdog!\n");
 178                 mpcore_wdt_keepalive(wdt);
 179         }
 180         clear_bit(0, &wdt->timer_alive);
 181         wdt->expect_close = 0;
 182         return 0;
 183 }
 184
 185 static ssize_t mpcore_wdt_write(struct file *file, const char *data,
 186                                                 size_t len, loff_t *ppos)
 187 {
 188         struct mpcore_wdt *wdt = file->private_data;
 189
 190         /*
 191          *      Refresh the timer.
 192          */
 193         if (len) {
 194                 if (!nowayout) {
 195                         size_t i;
 196
 197                         /* In case it was set long ago */
 198                         wdt->expect_close = 0;
 199
 200                         for (i = 0; i != len; i++) {
 201                                 char c;
 202
 203                                 if (get_user(c, data + i))
 204                                         return -EFAULT;
 205                                 if (c == 'V')
 206                                         wdt->expect_close = 42;
 207                         }
 208                 }
 209                 mpcore_wdt_keepalive(wdt);
 210         }
 211         return len;
 212 }
 213
 214 static struct watchdog_info ident = {
 215         .options                = WDIOF_SETTIMEOUT |
 216                                   WDIOF_KEEPALIVEPING |
 217                                   WDIOF_MAGICCLOSE,
 218         .identity               = "MPcore Watchdog",
 219 };
 220
 221 static long mpcore_wdt_ioctl(struct file *file, unsigned int cmd,
 222                                                         unsigned long arg)
 223 {
 224         struct mpcore_wdt *wdt = file->private_data;
 225         int ret;
 226         union {
 227                 struct watchdog_info ident;
 228                 int i;
 229         } uarg;
 230
 231         if (_IOC_DIR(cmd) && _IOC_SIZE(cmd) > sizeof(uarg))
 232                 return -ENOTTY;
 233
 234         if (_IOC_DIR(cmd) & _IOC_WRITE) {
 235                 ret = copy_from_user(&uarg, (void __user *)arg, _IOC_SIZE(cmd));
 236                 if (ret)
 237                         return -EFAULT;
 238         }
 239
 240         switch (cmd) {
 241         case WDIOC_GETSUPPORT:
 242                 uarg.ident = ident;
 243                 ret = 0;
 244                 break;
 245
 246         case WDIOC_GETSTATUS:
 247         case WDIOC_GETBOOTSTATUS:
 248                 uarg.i = 0;
 249                 ret = 0;
 250                 break;
 251
 252         case WDIOC_SETOPTIONS:
 253                 ret = -EINVAL;
 254                 if (uarg.i & WDIOS_DISABLECARD) {
 255                         mpcore_wdt_stop(wdt);
 256                         ret = 0;
 257                 }
 258                 if (uarg.i & WDIOS_ENABLECARD) {
 259                         mpcore_wdt_start(wdt);
 260                         ret = 0;
 261                 }
 262                 break;
 263
 264         case WDIOC_KEEPALIVE:
 265                 mpcore_wdt_keepalive(wdt);
 266                 ret = 0;
 267                 break;
 268
 269         case WDIOC_SETTIMEOUT:
 270                 ret = mpcore_wdt_set_heartbeat(uarg.i);
 271                 if (ret)
 272                         break;
 273
 274                 mpcore_wdt_keepalive(wdt);
 275                 /* Fall */
 276         case WDIOC_GETTIMEOUT:
 277                 uarg.i = mpcore_margin;
 278                 ret = 0;
 279                 break;
 280
 281         default:
 282                 return -ENOTTY;
 283         }
 284
 285         if (ret == 0 && _IOC_DIR(cmd) & _IOC_READ) {
 286                 ret = copy_to_user((void __user *)arg, &uarg, _IOC_SIZE(cmd));
 287                 if (ret)
 288                         ret = -EFAULT;
 289         }
 290         return ret;
 291 }
 292
 293 /*
 294  *      System shutdown handler.  Turn off the watchdog if we're
 295  *      restarting or halting the system.
 296  */
 297 static void mpcore_wdt_shutdown(struct platform_device *dev)
 298 {
 299         struct mpcore_wdt *wdt = platform_get_drvdata(dev);
 300
 301         if (system_state == SYSTEM_RESTART || system_state == SYSTEM_HALT)
 302                 mpcore_wdt_stop(wdt);
 303 }
 304
 305 /*
 306  *      Kernel Interfaces
 307  */
 308 static const struct file_operations mpcore_wdt_fops = {
 309         .owner          = THIS_MODULE,
 310         .llseek         = no_llseek,
 311         .write          = mpcore_wdt_write,
 312         .unlocked_ioctl = mpcore_wdt_ioctl,
 313         .open           = mpcore_wdt_open,
 314         .release        = mpcore_wdt_release,
 315 };
 316
 317 static struct miscdevice mpcore_wdt_miscdev = {
 318         .minor          = WATCHDOG_MINOR,
 319         .name           = "watchdog",
 320         .fops           = &mpcore_wdt_fops,
 321 };
 322
 323 static int __devinit mpcore_wdt_probe(struct platform_device *dev)
 324 {
 325         struct mpcore_wdt *wdt;
 326         struct resource *res;
 327         int ret;
 328
 329         /* We only accept one device, and it must have an id of -1 */
 330         if (dev->id != -1)
 331                 return -ENODEV;
 332
 333         res = platform_get_resource(dev, IORESOURCE_MEM, 0);
 334         if (!res) {
 335                 ret = -ENODEV;
 336                 goto err_out;
 337         }
 338
 339         wdt = kzalloc(sizeof(struct mpcore_wdt), GFP_KERNEL);
 340         if (!wdt) {
 341                 ret = -ENOMEM;
 342                 goto err_out;
 343         }
 344
 345         wdt->dev = &dev->dev;
 346         wdt->irq = platform_get_irq(dev, 0);
 347         if (wdt->irq < 0) {
 348                 ret = -ENXIO;
 349                 goto err_free;
 350         }
 351         wdt->base = ioremap(res->start, res->end - res->start + 1);
 352         if (!wdt->base) {
 353                 ret = -ENOMEM;
 354                 goto err_free;
 355         }
 356
 357         mpcore_wdt_miscdev.parent = &dev->dev;
 358         ret = misc_register(&mpcore_wdt_miscdev);
 359         if (ret) {
 360                 dev_printk(KERN_ERR, _dev,
 361                         "cannot register miscdev on minor=%d (err=%d)\n",
 362                                                         WATCHDOG_MINOR, ret);
 363                 goto err_misc;
 364         }
 365
 366         ret = request_irq(wdt->irq, mpcore_wdt_fire, IRQF_DISABLED,
 367                                                         "mpcore_wdt", wdt);
 368         if (ret) {
 369                 dev_printk(KERN_ERR, _dev,
 370                         "cannot register IRQ%d for watchdog\n", wdt->irq);
 371                 goto err_irq;
 372         }
 373
 374         mpcore_wdt_stop(wdt);
 375         platform_set_drvdata(&dev->dev, wdt);
 376         mpcore_wdt_dev = dev;
 377
 378         return 0;
 379
 380 err_irq:
 381         misc_deregister(&mpcore_wdt_miscdev);
 382 err_misc:
 383         iounmap(wdt->base);
 384 err_free:
 385         kfree(wdt);
 386 err_out:
 387         return ret;
 388 }
 389
 390 static int __devexit mpcore_wdt_remove(struct platform_device *dev)
 391 {
 392         struct mpcore_wdt *wdt = platform_get_drvdata(dev);
 393
 394         platform_set_drvdata(dev, NULL);
 395
 396         misc_deregister(&mpcore_wdt_miscdev);
 397
 398         mpcore_wdt_dev = NULL;
 399
 400         free_irq(wdt->irq, wdt);
 401         iounmap(wdt->base);
 402         kfree(wdt);
 403         return 0;
 404 }
 405
 406 /* work with hotplug and coldplug */
 407 MODULE_ALIAS("platform:mpcore_wdt");
 408
 409 static struct platform_driver mpcore_wdt_driver = {
 410         .probe          = mpcore_wdt_probe,
 411         .remove         = __devexit_p(mpcore_wdt_remove),
 412         .shutdown       = mpcore_wdt_shutdown,
 413         .driver         = {
 414                 .owner  = THIS_MODULE,
 415                 .name   = "mpcore_wdt",
 416         },
 417 };
 418
 419 static char banner[] __initdata = KERN_INFO "MPcore Watchdog Timer: 0.1. mpcore_noboot=%d mpcore_margin=%d sec (nowayout= %d)\n";
 420
 421 static int __init mpcore_wdt_init(void)
 422 {
 423         /*
 424          * Check that the margin value is within it's range;
 425          * if not reset to the default
 426          */
 427         if (mpcore_wdt_set_heartbeat(mpcore_margin)) {
 428                 mpcore_wdt_set_heartbeat(TIMER_MARGIN);
 429                 printk(KERN_INFO "mpcore_margin value must be 0 < mpcore_margin < 65536, using %d\n",
 430                         TIMER_MARGIN);
 431         }
 432
 433         printk(banner, mpcore_noboot, mpcore_margin, nowayout);
 434
 435         return platform_driver_register(&mpcore_wdt_driver);
 436 }
 437
 438 static void __exit mpcore_wdt_exit(void)
 439 {
 440         platform_driver_unregister(&mpcore_wdt_driver);
 441 }
 442
 443 module_init(mpcore_wdt_init);
 444 module_exit(mpcore_wdt_exit);
 445
 446 MODULE_AUTHOR("ARM Limited");
 447 MODULE_DESCRIPTION("MPcore Watchdog Device Driver");
 448 MODULE_LICENSE("GPL");
 449 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);