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
  23 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  24
  25 #include <linux/module.h>
  26 #include <linux/moduleparam.h>
  27 #include <linux/types.h>
  28 #include <linux/miscdevice.h>
  29 #include <linux/watchdog.h>
  30 #include <linux/fs.h>
  31 #include <linux/reboot.h>
  32 #include <linux/init.h>
  33 #include <linux/interrupt.h>
  34 #include <linux/platform_device.h>
  35 #include <linux/uaccess.h>
  36 #include <linux/slab.h>
  37 #include <linux/io.h>
  38
  39 #include <asm/smp_twd.h>
  40
  41 struct mpcore_wdt {
  42         unsigned long   timer_alive;
  43         struct device   *dev;
  44         void __iomem    *base;
  45         int             irq;
  46         unsigned int    perturb;
  47         char            expect_close;
  48 };
  49
  50 static struct platform_device *mpcore_wdt_pdev;
  51 static DEFINE_SPINLOCK(wdt_lock);
  52
  53 #define TIMER_MARGIN    60
  54 static int mpcore_margin = TIMER_MARGIN;
  55 module_param(mpcore_margin, int, 0);
  56 MODULE_PARM_DESC(mpcore_margin,
  57         "MPcore timer margin in seconds. (0 < mpcore_margin < 65536, default="
  58                                 __MODULE_STRING(TIMER_MARGIN) ")");
  59
  60 static bool nowayout = WATCHDOG_NOWAYOUT;
  61 module_param(nowayout, bool, 0);
  62 MODULE_PARM_DESC(nowayout,
  63         "Watchdog cannot be stopped once started (default="
  64                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  65
  66 #define ONLY_TESTING    0
  67 static int mpcore_noboot = ONLY_TESTING;
  68 module_param(mpcore_noboot, int, 0);
  69 MODULE_PARM_DESC(mpcore_noboot, "MPcore watchdog action, "
  70         "set to 1 to ignore reboots, 0 to reboot (default="
  71                                         __MODULE_STRING(ONLY_TESTING) ")");
  72
  73 /*
  74  *      This is the interrupt handler.  Note that we only use this
  75  *      in testing mode, so don't actually do a reboot here.
  76  */
  77 static irqreturn_t mpcore_wdt_fire(int irq, void *arg)
  78 {
  79         struct mpcore_wdt *wdt = arg;
  80
  81         /* Check it really was our interrupt */
  82         if (readl(wdt->base + TWD_WDOG_INTSTAT)) {
  83                 dev_crit(wdt->dev, "Triggered - Reboot ignored\n");
  84                 /* Clear the interrupt on the watchdog */
  85                 writel(1, wdt->base + TWD_WDOG_INTSTAT);
  86                 return IRQ_HANDLED;
  87         }
  88         return IRQ_NONE;
  89 }
  90
  91 /*
  92  *      mpcore_wdt_keepalive - reload the timer
  93  *
  94  *      Note that the spec says a DIFFERENT value must be written to the reload
  95  *      register each time.  The "perturb" variable deals with this by adding 1
  96  *      to the count every other time the function is called.
  97  */
  98 static void mpcore_wdt_keepalive(struct mpcore_wdt *wdt)
  99 {
 100         unsigned long count;
 101
 102         spin_lock(&wdt_lock);
 103         /* Assume prescale is set to 256 */
 104         count =  __raw_readl(wdt->base + TWD_WDOG_COUNTER);
 105         count = (0xFFFFFFFFU - count) * (HZ / 5);
 106         count = (count / 256) * mpcore_margin;
 107
 108         /* Reload the counter */
 109         writel(count + wdt->perturb, wdt->base + TWD_WDOG_LOAD);
 110         wdt->perturb = wdt->perturb ? 0 : 1;
 111         spin_unlock(&wdt_lock);
 112 }
 113
 114 static void mpcore_wdt_stop(struct mpcore_wdt *wdt)
 115 {
 116         spin_lock(&wdt_lock);
 117         writel(0x12345678, wdt->base + TWD_WDOG_DISABLE);
 118         writel(0x87654321, wdt->base + TWD_WDOG_DISABLE);
 119         writel(0x0, wdt->base + TWD_WDOG_CONTROL);
 120         spin_unlock(&wdt_lock);
 121 }
 122
 123 static void mpcore_wdt_start(struct mpcore_wdt *wdt)
 124 {
 125         dev_info(wdt->dev, "enabling watchdog\n");
 126
 127         /* This loads the count register but does NOT start the count yet */
 128         mpcore_wdt_keepalive(wdt);
 129
 130         if (mpcore_noboot) {
 131                 /* Enable watchdog - prescale=256, watchdog mode=0, enable=1 */
 132                 writel(0x0000FF01, wdt->base + TWD_WDOG_CONTROL);
 133         } else {
 134                 /* Enable watchdog - prescale=256, watchdog mode=1, enable=1 */
 135                 writel(0x0000FF09, wdt->base + TWD_WDOG_CONTROL);
 136         }
 137 }
 138
 139 static int mpcore_wdt_set_heartbeat(int t)
 140 {
 141         if (t < 0x0001 || t > 0xFFFF)
 142                 return -EINVAL;
 143
 144         mpcore_margin = t;
 145         return 0;
 146 }
 147
 148 /*
 149  *      /dev/watchdog handling
 150  */
 151 static int mpcore_wdt_open(struct inode *inode, struct file *file)
 152 {
 153         struct mpcore_wdt *wdt = platform_get_drvdata(mpcore_wdt_pdev);
 154
 155         if (test_and_set_bit(0, &wdt->timer_alive))
 156                 return -EBUSY;
 157
 158         if (nowayout)
 159                 __module_get(THIS_MODULE);
 160
 161         file->private_data = wdt;
 162
 163         /*
 164          *      Activate timer
 165          */
 166         mpcore_wdt_start(wdt);
 167
 168         return nonseekable_open(inode, file);
 169 }
 170
 171 static int mpcore_wdt_release(struct inode *inode, struct file *file)
 172 {
 173         struct mpcore_wdt *wdt = file->private_data;
 174
 175         /*
 176          *      Shut off the timer.
 177          *      Lock it in if it's a module and we set nowayout
 178          */
 179         if (wdt->expect_close == 42)
 180                 mpcore_wdt_stop(wdt);
 181         else {
 182                 dev_crit(wdt->dev,
 183                          "unexpected close, not stopping watchdog!\n");
 184                 mpcore_wdt_keepalive(wdt);
 185         }
 186         clear_bit(0, &wdt->timer_alive);
 187         wdt->expect_close = 0;
 188         return 0;
 189 }
 190
 191 static ssize_t mpcore_wdt_write(struct file *file, const char *data,
 192                                                 size_t len, loff_t *ppos)
 193 {
 194         struct mpcore_wdt *wdt = file->private_data;
 195
 196         /*
 197          *      Refresh the timer.
 198          */
 199         if (len) {
 200                 if (!nowayout) {
 201                         size_t i;
 202
 203                         /* In case it was set long ago */
 204                         wdt->expect_close = 0;
 205
 206                         for (i = 0; i != len; i++) {
 207                                 char c;
 208
 209                                 if (get_user(c, data + i))
 210                                         return -EFAULT;
 211                                 if (c == 'V')
 212                                         wdt->expect_close = 42;
 213                         }
 214                 }
 215                 mpcore_wdt_keepalive(wdt);
 216         }
 217         return len;
 218 }
 219
 220 static const struct watchdog_info ident = {
 221         .options                = WDIOF_SETTIMEOUT |
 222                                   WDIOF_KEEPALIVEPING |
 223                                   WDIOF_MAGICCLOSE,
 224         .identity               = "MPcore Watchdog",
 225 };
 226
 227 static long mpcore_wdt_ioctl(struct file *file, unsigned int cmd,
 228                                                         unsigned long arg)
 229 {
 230         struct mpcore_wdt *wdt = file->private_data;
 231         int ret;
 232         union {
 233                 struct watchdog_info ident;
 234                 int i;
 235         } uarg;
 236
 237         if (_IOC_DIR(cmd) && _IOC_SIZE(cmd) > sizeof(uarg))
 238                 return -ENOTTY;
 239
 240         if (_IOC_DIR(cmd) & _IOC_WRITE) {
 241                 ret = copy_from_user(&uarg, (void __user *)arg, _IOC_SIZE(cmd));
 242                 if (ret)
 243                         return -EFAULT;
 244         }
 245
 246         switch (cmd) {
 247         case WDIOC_GETSUPPORT:
 248                 uarg.ident = ident;
 249                 ret = 0;
 250                 break;
 251
 252         case WDIOC_GETSTATUS:
 253         case WDIOC_GETBOOTSTATUS:
 254                 uarg.i = 0;
 255                 ret = 0;
 256                 break;
 257
 258         case WDIOC_SETOPTIONS:
 259                 ret = -EINVAL;
 260                 if (uarg.i & WDIOS_DISABLECARD) {
 261                         mpcore_wdt_stop(wdt);
 262                         ret = 0;
 263                 }
 264                 if (uarg.i & WDIOS_ENABLECARD) {
 265                         mpcore_wdt_start(wdt);
 266                         ret = 0;
 267                 }
 268                 break;
 269
 270         case WDIOC_KEEPALIVE:
 271                 mpcore_wdt_keepalive(wdt);
 272                 ret = 0;
 273                 break;
 274
 275         case WDIOC_SETTIMEOUT:
 276                 ret = mpcore_wdt_set_heartbeat(uarg.i);
 277                 if (ret)
 278                         break;
 279
 280                 mpcore_wdt_keepalive(wdt);
 281                 /* Fall */
 282         case WDIOC_GETTIMEOUT:
 283                 uarg.i = mpcore_margin;
 284                 ret = 0;
 285                 break;
 286
 287         default:
 288                 return -ENOTTY;
 289         }
 290
 291         if (ret == 0 && _IOC_DIR(cmd) & _IOC_READ) {
 292                 ret = copy_to_user((void __user *)arg, &uarg, _IOC_SIZE(cmd));
 293                 if (ret)
 294                         ret = -EFAULT;
 295         }
 296         return ret;
 297 }
 298
 299 /*
 300  *      System shutdown handler.  Turn off the watchdog if we're
 301  *      restarting or halting the system.
 302  */
 303 static void mpcore_wdt_shutdown(struct platform_device *pdev)
 304 {
 305         struct mpcore_wdt *wdt = platform_get_drvdata(pdev);
 306
 307         if (system_state == SYSTEM_RESTART || system_state == SYSTEM_HALT)
 308                 mpcore_wdt_stop(wdt);
 309 }
 310
 311 /*
 312  *      Kernel Interfaces
 313  */
 314 static const struct file_operations mpcore_wdt_fops = {
 315         .owner          = THIS_MODULE,
 316         .llseek         = no_llseek,
 317         .write          = mpcore_wdt_write,
 318         .unlocked_ioctl = mpcore_wdt_ioctl,
 319         .open           = mpcore_wdt_open,
 320         .release        = mpcore_wdt_release,
 321 };
 322
 323 static struct miscdevice mpcore_wdt_miscdev = {
 324         .minor          = WATCHDOG_MINOR,
 325         .name           = "watchdog",
 326         .fops           = &mpcore_wdt_fops,
 327 };
 328
 329 static int mpcore_wdt_probe(struct platform_device *pdev)
 330 {
 331         struct mpcore_wdt *wdt;
 332         struct resource *res;
 333         int ret;
 334
 335         /* We only accept one device, and it must have an id of -1 */
 336         if (pdev->id != -1)
 337                 return -ENODEV;
 338
 339         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 340         if (!res)
 341                 return -ENODEV;
 342
 343         wdt = devm_kzalloc(&pdev->dev, sizeof(struct mpcore_wdt), GFP_KERNEL);
 344         if (!wdt)
 345                 return -ENOMEM;
 346
 347         wdt->dev = &pdev->dev;
 348         wdt->irq = platform_get_irq(pdev, 0);
 349         if (wdt->irq >= 0) {
 350                 ret = devm_request_irq(wdt->dev, wdt->irq, mpcore_wdt_fire, 0,
 351                                 "mpcore_wdt", wdt);
 352                 if (ret) {
 353                         dev_err(wdt->dev,
 354                                 "cannot register IRQ%d for watchdog\n",
 355                                 wdt->irq);
 356                         return ret;
 357                 }
 358         }
 359
 360         wdt->base = devm_ioremap(wdt->dev, res->start, resource_size(res));
 361         if (!wdt->base)
 362                 return -ENOMEM;
 363
 364         mpcore_wdt_miscdev.parent = &pdev->dev;
 365         ret = misc_register(&mpcore_wdt_miscdev);
 366         if (ret) {
 367                 dev_err(wdt->dev,
 368                         "cannot register miscdev on minor=%d (err=%d)\n",
 369                         WATCHDOG_MINOR, ret);
 370                 return ret;
 371         }
 372
 373         mpcore_wdt_stop(wdt);
 374         platform_set_drvdata(pdev, wdt);
 375         mpcore_wdt_pdev = pdev;
 376
 377         return 0;
 378 }
 379
 380 static int mpcore_wdt_remove(struct platform_device *pdev)
 381 {
 382         platform_set_drvdata(pdev, NULL);
 383
 384         misc_deregister(&mpcore_wdt_miscdev);
 385
 386         mpcore_wdt_pdev = NULL;
 387
 388         return 0;
 389 }
 390
 391 #ifdef CONFIG_PM
 392 static int mpcore_wdt_suspend(struct platform_device *pdev, pm_message_t msg)
 393 {
 394         struct mpcore_wdt *wdt = platform_get_drvdata(pdev);
 395         mpcore_wdt_stop(wdt);           /* Turn the WDT off */
 396         return 0;
 397 }
 398
 399 static int mpcore_wdt_resume(struct platform_device *pdev)
 400 {
 401         struct mpcore_wdt *wdt = platform_get_drvdata(pdev);
 402         /* re-activate timer */
 403         if (test_bit(0, &wdt->timer_alive))
 404                 mpcore_wdt_start(wdt);
 405         return 0;
 406 }
 407 #else
 408 #define mpcore_wdt_suspend      NULL
 409 #define mpcore_wdt_resume       NULL
 410 #endif
 411
 412 /* work with hotplug and coldplug */
 413 MODULE_ALIAS("platform:mpcore_wdt");
 414
 415 static struct platform_driver mpcore_wdt_driver = {
 416         .probe          = mpcore_wdt_probe,
 417         .remove         = mpcore_wdt_remove,
 418         .suspend        = mpcore_wdt_suspend,
 419         .resume         = mpcore_wdt_resume,
 420         .shutdown       = mpcore_wdt_shutdown,
 421         .driver         = {
 422                 .owner  = THIS_MODULE,
 423                 .name   = "mpcore_wdt",
 424         },
 425 };
 426
 427 static int __init mpcore_wdt_init(void)
 428 {
 429         /*
 430          * Check that the margin value is within it's range;
 431          * if not reset to the default
 432          */
 433         if (mpcore_wdt_set_heartbeat(mpcore_margin)) {
 434                 mpcore_wdt_set_heartbeat(TIMER_MARGIN);
 435                 pr_info("mpcore_margin value must be 0 < mpcore_margin < 65536, using %d\n",
 436                         TIMER_MARGIN);
 437         }
 438
 439         pr_info("MPcore Watchdog Timer: 0.1. mpcore_noboot=%d mpcore_margin=%d sec (nowayout= %d)\n",
 440                 mpcore_noboot, mpcore_margin, nowayout);
 441
 442         return platform_driver_register(&mpcore_wdt_driver);
 443 }
 444
 445 static void __exit mpcore_wdt_exit(void)
 446 {
 447         platform_driver_unregister(&mpcore_wdt_driver);
 448 }
 449
 450 module_init(mpcore_wdt_init);
 451 module_exit(mpcore_wdt_exit);
 452
 453 MODULE_AUTHOR("ARM Limited");
 454 MODULE_DESCRIPTION("MPcore Watchdog Device Driver");
 455 MODULE_LICENSE("GPL");
 456 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);