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 #include <linux/slab.h>
  34 #include <linux/io.h>
  35
  36 #include <asm/smp_twd.h>
  37
  38 struct mpcore_wdt {
  39         unsigned long   timer_alive;
  40         struct device   *dev;
  41         void __iomem    *base;
  42         int             irq;
  43         unsigned int    perturb;
  44         char            expect_close;
  45 };
  46
  47 static struct platform_device *mpcore_wdt_dev;
  48 static DEFINE_SPINLOCK(wdt_lock);
  49
  50 #define TIMER_MARGIN    60
  51 static int mpcore_margin = TIMER_MARGIN;
  52 module_param(mpcore_margin, int, 0);
  53 MODULE_PARM_DESC(mpcore_margin,
  54         "MPcore timer margin in seconds. (0 < mpcore_margin < 65536, default="
  55                                 __MODULE_STRING(TIMER_MARGIN) ")");
  56
  57 static int nowayout = WATCHDOG_NOWAYOUT;
  58 module_param(nowayout, int, 0);
  59 MODULE_PARM_DESC(nowayout,
  60         "Watchdog cannot be stopped once started (default="
  61                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  62
  63 #define ONLY_TESTING    0
  64 static int mpcore_noboot = ONLY_TESTING;
  65 module_param(mpcore_noboot, int, 0);
  66 MODULE_PARM_DESC(mpcore_noboot, "MPcore watchdog action, "
  67         "set to 1 to ignore reboots, 0 to reboot (default="
  68                                         __MODULE_STRING(ONLY_TESTING) ")");
  69
  70 /*
  71  *      This is the interrupt handler.  Note that we only use this
  72  *      in testing mode, so don't actually do a reboot here.
  73  */
  74 static irqreturn_t mpcore_wdt_fire(int irq, void *arg)
  75 {
  76         struct mpcore_wdt *wdt = arg;
  77
  78         /* Check it really was our interrupt */
  79         if (readl(wdt->base + TWD_WDOG_INTSTAT)) {
  80                 dev_printk(KERN_CRIT, wdt->dev,
  81                                         "Triggered - Reboot ignored.\n");
  82                 /* Clear the interrupt on the watchdog */
  83                 writel(1, wdt->base + TWD_WDOG_INTSTAT);
  84                 return IRQ_HANDLED;
  85         }
  86         return IRQ_NONE;
  87 }
  88
  89 /*
  90  *      mpcore_wdt_keepalive - reload the timer
  91  *
  92  *      Note that the spec says a DIFFERENT value must be written to the reload
  93  *      register each time.  The "perturb" variable deals with this by adding 1
  94  *      to the count every other time the function is called.
  95  */
  96 static void mpcore_wdt_keepalive(struct mpcore_wdt *wdt)
  97 {
  98         unsigned long count;
  99
 100         spin_lock(&wdt_lock);
 101         /* Assume prescale is set to 256 */
 102         count =  __raw_readl(wdt->base + TWD_WDOG_COUNTER);
 103         count = (0xFFFFFFFFU - count) * (HZ / 5);
 104         count = (count / 256) * mpcore_margin;
 105
 106         /* Reload the counter */
 107         writel(count + wdt->perturb, wdt->base + TWD_WDOG_LOAD);
 108         wdt->perturb = wdt->perturb ? 0 : 1;
 109         spin_unlock(&wdt_lock);
 110 }
 111
 112 static void mpcore_wdt_stop(struct mpcore_wdt *wdt)
 113 {
 114         spin_lock(&wdt_lock);
 115         writel(0x12345678, wdt->base + TWD_WDOG_DISABLE);
 116         writel(0x87654321, wdt->base + TWD_WDOG_DISABLE);
 117         writel(0x0, wdt->base + TWD_WDOG_CONTROL);
 118         spin_unlock(&wdt_lock);
 119 }
 120
 121 static void mpcore_wdt_start(struct mpcore_wdt *wdt)
 122 {
 123         dev_printk(KERN_INFO, wdt->dev, "enabling watchdog.\n");
 124
 125         /* This loads the count register but does NOT start the count yet */
 126         mpcore_wdt_keepalive(wdt);
 127
 128         if (mpcore_noboot) {
 129                 /* Enable watchdog - prescale=256, watchdog mode=0, enable=1 */
 130                 writel(0x0000FF01, wdt->base + TWD_WDOG_CONTROL);
 131         } else {
 132                 /* Enable watchdog - prescale=256, watchdog mode=1, enable=1 */
 133                 writel(0x0000FF09, wdt->base + TWD_WDOG_CONTROL);
 134         }
 135 }
 136
 137 static int mpcore_wdt_set_heartbeat(int t)
 138 {
 139         if (t < 0x0001 || t > 0xFFFF)
 140                 return -EINVAL;
 141
 142         mpcore_margin = t;
 143         return 0;
 144 }
 145
 146 /*
 147  *      /dev/watchdog handling
 148  */
 149 static int mpcore_wdt_open(struct inode *inode, struct file *file)
 150 {
 151         struct mpcore_wdt *wdt = platform_get_drvdata(mpcore_wdt_dev);
 152
 153         if (test_and_set_bit(0, &wdt->timer_alive))
 154                 return -EBUSY;
 155
 156         if (nowayout)
 157                 __module_get(THIS_MODULE);
 158
 159         file->private_data = wdt;
 160
 161         /*
 162          *      Activate timer
 163          */
 164         mpcore_wdt_start(wdt);
 165
 166         return nonseekable_open(inode, file);
 167 }
 168
 169 static int mpcore_wdt_release(struct inode *inode, struct file *file)
 170 {
 171         struct mpcore_wdt *wdt = file->private_data;
 172
 173         /*
 174          *      Shut off the timer.
 175          *      Lock it in if it's a module and we set nowayout
 176          */
 177         if (wdt->expect_close == 42)
 178                 mpcore_wdt_stop(wdt);
 179         else {
 180                 dev_printk(KERN_CRIT, wdt->dev,
 181                                 "unexpected close, not stopping watchdog!\n");
 182                 mpcore_wdt_keepalive(wdt);
 183         }
 184         clear_bit(0, &wdt->timer_alive);
 185         wdt->expect_close = 0;
 186         return 0;
 187 }
 188
 189 static ssize_t mpcore_wdt_write(struct file *file, const char *data,
 190                                                 size_t len, loff_t *ppos)
 191 {
 192         struct mpcore_wdt *wdt = file->private_data;
 193
 194         /*
 195          *      Refresh the timer.
 196          */
 197         if (len) {
 198                 if (!nowayout) {
 199                         size_t i;
 200
 201                         /* In case it was set long ago */
 202                         wdt->expect_close = 0;
 203
 204                         for (i = 0; i != len; i++) {
 205                                 char c;
 206
 207                                 if (get_user(c, data + i))
 208                                         return -EFAULT;
 209                                 if (c == 'V')
 210                                         wdt->expect_close = 42;
 211                         }
 212                 }
 213                 mpcore_wdt_keepalive(wdt);
 214         }
 215         return len;
 216 }
 217
 218 static const struct watchdog_info ident = {
 219         .options                = WDIOF_SETTIMEOUT |
 220                                   WDIOF_KEEPALIVEPING |
 221                                   WDIOF_MAGICCLOSE,
 222         .identity               = "MPcore Watchdog",
 223 };
 224
 225 static long mpcore_wdt_ioctl(struct file *file, unsigned int cmd,
 226                                                         unsigned long arg)
 227 {
 228         struct mpcore_wdt *wdt = file->private_data;
 229         int ret;
 230         union {
 231                 struct watchdog_info ident;
 232                 int i;
 233         } uarg;
 234
 235         if (_IOC_DIR(cmd) && _IOC_SIZE(cmd) > sizeof(uarg))
 236                 return -ENOTTY;
 237
 238         if (_IOC_DIR(cmd) & _IOC_WRITE) {
 239                 ret = copy_from_user(&uarg, (void __user *)arg, _IOC_SIZE(cmd));
 240                 if (ret)
 241                         return -EFAULT;
 242         }
 243
 244         switch (cmd) {
 245         case WDIOC_GETSUPPORT:
 246                 uarg.ident = ident;
 247                 ret = 0;
 248                 break;
 249
 250         case WDIOC_GETSTATUS:
 251         case WDIOC_GETBOOTSTATUS:
 252                 uarg.i = 0;
 253                 ret = 0;
 254                 break;
 255
 256         case WDIOC_SETOPTIONS:
 257                 ret = -EINVAL;
 258                 if (uarg.i & WDIOS_DISABLECARD) {
 259                         mpcore_wdt_stop(wdt);
 260                         ret = 0;
 261                 }
 262                 if (uarg.i & WDIOS_ENABLECARD) {
 263                         mpcore_wdt_start(wdt);
 264                         ret = 0;
 265                 }
 266                 break;
 267
 268         case WDIOC_KEEPALIVE:
 269                 mpcore_wdt_keepalive(wdt);
 270                 ret = 0;
 271                 break;
 272
 273         case WDIOC_SETTIMEOUT:
 274                 ret = mpcore_wdt_set_heartbeat(uarg.i);
 275                 if (ret)
 276                         break;
 277
 278                 mpcore_wdt_keepalive(wdt);
 279                 /* Fall */
 280         case WDIOC_GETTIMEOUT:
 281                 uarg.i = mpcore_margin;
 282                 ret = 0;
 283                 break;
 284
 285         default:
 286                 return -ENOTTY;
 287         }
 288
 289         if (ret == 0 && _IOC_DIR(cmd) & _IOC_READ) {
 290                 ret = copy_to_user((void __user *)arg, &uarg, _IOC_SIZE(cmd));
 291                 if (ret)
 292                         ret = -EFAULT;
 293         }
 294         return ret;
 295 }
 296
 297 /*
 298  *      System shutdown handler.  Turn off the watchdog if we're
 299  *      restarting or halting the system.
 300  */
 301 static void mpcore_wdt_shutdown(struct platform_device *dev)
 302 {
 303         struct mpcore_wdt *wdt = platform_get_drvdata(dev);
 304
 305         if (system_state == SYSTEM_RESTART || system_state == SYSTEM_HALT)
 306                 mpcore_wdt_stop(wdt);
 307 }
 308
 309 /*
 310  *      Kernel Interfaces
 311  */
 312 static const struct file_operations mpcore_wdt_fops = {
 313         .owner          = THIS_MODULE,
 314         .llseek         = no_llseek,
 315         .write          = mpcore_wdt_write,
 316         .unlocked_ioctl = mpcore_wdt_ioctl,
 317         .open           = mpcore_wdt_open,
 318         .release        = mpcore_wdt_release,
 319 };
 320
 321 static struct miscdevice mpcore_wdt_miscdev = {
 322         .minor          = WATCHDOG_MINOR,
 323         .name           = "watchdog",
 324         .fops           = &mpcore_wdt_fops,
 325 };
 326
 327 static int __devinit mpcore_wdt_probe(struct platform_device *dev)
 328 {
 329         struct mpcore_wdt *wdt;
 330         struct resource *res;
 331         int ret;
 332
 333         /* We only accept one device, and it must have an id of -1 */
 334         if (dev->id != -1)
 335                 return -ENODEV;
 336
 337         res = platform_get_resource(dev, IORESOURCE_MEM, 0);
 338         if (!res) {
 339                 ret = -ENODEV;
 340                 goto err_out;
 341         }
 342
 343         wdt = kzalloc(sizeof(struct mpcore_wdt), GFP_KERNEL);
 344         if (!wdt) {
 345                 ret = -ENOMEM;
 346                 goto err_out;
 347         }
 348
 349         wdt->dev = &dev->dev;
 350         wdt->irq = platform_get_irq(dev, 0);
 351         if (wdt->irq < 0) {
 352                 ret = -ENXIO;
 353                 goto err_free;
 354         }
 355         wdt->base = ioremap(res->start, resource_size(res));
 356         if (!wdt->base) {
 357                 ret = -ENOMEM;
 358                 goto err_free;
 359         }
 360
 361         mpcore_wdt_miscdev.parent = &dev->dev;
 362         ret = misc_register(&mpcore_wdt_miscdev);
 363         if (ret) {
 364                 dev_printk(KERN_ERR, wdt->dev,
 365                         "cannot register miscdev on minor=%d (err=%d)\n",
 366                                                         WATCHDOG_MINOR, ret);
 367                 goto err_misc;
 368         }
 369
 370         ret = request_irq(wdt->irq, mpcore_wdt_fire, IRQF_DISABLED,
 371                                                         "mpcore_wdt", wdt);
 372         if (ret) {
 373                 dev_printk(KERN_ERR, wdt->dev,
 374                         "cannot register IRQ%d for watchdog\n", wdt->irq);
 375                 goto err_irq;
 376         }
 377
 378         mpcore_wdt_stop(wdt);
 379         platform_set_drvdata(dev, wdt);
 380         mpcore_wdt_dev = dev;
 381
 382         return 0;
 383
 384 err_irq:
 385         misc_deregister(&mpcore_wdt_miscdev);
 386 err_misc:
 387         iounmap(wdt->base);
 388 err_free:
 389         kfree(wdt);
 390 err_out:
 391         return ret;
 392 }
 393
 394 static int __devexit mpcore_wdt_remove(struct platform_device *dev)
 395 {
 396         struct mpcore_wdt *wdt = platform_get_drvdata(dev);
 397
 398         platform_set_drvdata(dev, NULL);
 399
 400         misc_deregister(&mpcore_wdt_miscdev);
 401
 402         mpcore_wdt_dev = NULL;
 403
 404         free_irq(wdt->irq, wdt);
 405         iounmap(wdt->base);
 406         kfree(wdt);
 407         return 0;
 408 }
 409
 410 /* work with hotplug and coldplug */
 411 MODULE_ALIAS("platform:mpcore_wdt");
 412
 413 static struct platform_driver mpcore_wdt_driver = {
 414         .probe          = mpcore_wdt_probe,
 415         .remove         = __devexit_p(mpcore_wdt_remove),
 416         .shutdown       = mpcore_wdt_shutdown,
 417         .driver         = {
 418                 .owner  = THIS_MODULE,
 419                 .name   = "mpcore_wdt",
 420         },
 421 };
 422
 423 static char banner[] __initdata = KERN_INFO "MPcore Watchdog Timer: 0.1. "
 424                 "mpcore_noboot=%d mpcore_margin=%d sec (nowayout= %d)\n";
 425
 426 static int __init mpcore_wdt_init(void)
 427 {
 428         /*
 429          * Check that the margin value is within it's range;
 430          * if not reset to the default
 431          */
 432         if (mpcore_wdt_set_heartbeat(mpcore_margin)) {
 433                 mpcore_wdt_set_heartbeat(TIMER_MARGIN);
 434                 printk(KERN_INFO "mpcore_margin value must be 0 < mpcore_margin < 65536, using %d\n",
 435                         TIMER_MARGIN);
 436         }
 437
 438         printk(banner, mpcore_noboot, mpcore_margin, nowayout);
 439
 440         return platform_driver_register(&mpcore_wdt_driver);
 441 }
 442
 443 static void __exit mpcore_wdt_exit(void)
 444 {
 445         platform_driver_unregister(&mpcore_wdt_driver);
 446 }
 447
 448 module_init(mpcore_wdt_init);
 449 module_exit(mpcore_wdt_exit);
 450
 451 MODULE_AUTHOR("ARM Limited");
 452 MODULE_DESCRIPTION("MPcore Watchdog Device Driver");
 453 MODULE_LICENSE("GPL");
 454 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);