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