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