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