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