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