drivers/watchdog/shwdt.c

   1 /*
   2  * drivers/watchdog/shwdt.c
   3  *
   4  * Watchdog driver for integrated watchdog in the SuperH processors.
   5  *
   6  * Copyright (C) 2001 - 2010  Paul Mundt <lethal@linux-sh.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU General Public License as published by the
  10  * Free Software Foundation; either version 2 of the License, or (at your
  11  * option) any later version.
  12  *
  13  * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
  14  *     Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
  15  *
  16  * 19-Apr-2002 Rob Radez <rob@osinvestor.com>
  17  *     Added expect close support, made emulated timeout runtime changeable
  18  *     general cleanups, add some ioctls
  19  */
  20
  21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  22
  23 #include <linux/module.h>
  24 #include <linux/moduleparam.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/init.h>
  27 #include <linux/types.h>
  28 #include <linux/miscdevice.h>
  29 #include <linux/watchdog.h>
  30 #include <linux/reboot.h>
  31 #include <linux/notifier.h>
  32 #include <linux/ioport.h>
  33 #include <linux/fs.h>
  34 #include <linux/mm.h>
  35 #include <linux/slab.h>
  36 #include <linux/io.h>
  37 #include <linux/uaccess.h>
  38 #include <asm/watchdog.h>
  39
  40 #define DRV_NAME "sh-wdt"
  41
  42 /*
  43  * Default clock division ratio is 5.25 msecs. For an additional table of
  44  * values, consult the asm-sh/watchdog.h. Overload this at module load
  45  * time.
  46  *
  47  * In order for this to work reliably we need to have HZ set to 1000 or
  48  * something quite higher than 100 (or we need a proper high-res timer
  49  * implementation that will deal with this properly), otherwise the 10ms
  50  * resolution of a jiffy is enough to trigger the overflow. For things like
  51  * the SH-4 and SH-5, this isn't necessarily that big of a problem, though
  52  * for the SH-2 and SH-3, this isn't recommended unless the WDT is absolutely
  53  * necssary.
  54  *
  55  * As a result of this timing problem, the only modes that are particularly
  56  * feasible are the 4096 and the 2048 divisors, which yield 5.25 and 2.62ms
  57  * overflow periods respectively.
  58  *
  59  * Also, since we can't really expect userspace to be responsive enough
  60  * before the overflow happens, we maintain two separate timers .. One in
  61  * the kernel for clearing out WOVF every 2ms or so (again, this depends on
  62  * HZ == 1000), and another for monitoring userspace writes to the WDT device.
  63  *
  64  * As such, we currently use a configurable heartbeat interval which defaults
  65  * to 30s. In this case, the userspace daemon is only responsible for periodic
  66  * writes to the device before the next heartbeat is scheduled. If the daemon
  67  * misses its deadline, the kernel timer will allow the WDT to overflow.
  68  */
  69 static int clock_division_ratio = WTCSR_CKS_4096;
  70 #define next_ping_period(cks)   (jiffies + msecs_to_jiffies(cks - 4))
  71
  72 static const struct watchdog_info sh_wdt_info;
  73 static struct platform_device *sh_wdt_dev;
  74 static DEFINE_SPINLOCK(shwdt_lock);
  75
  76 #define WATCHDOG_HEARTBEAT 30                   /* 30 sec default heartbeat */
  77 static int heartbeat = WATCHDOG_HEARTBEAT;      /* in seconds */
  78 static bool nowayout = WATCHDOG_NOWAYOUT;
  79 static unsigned long next_heartbeat;
  80
  81 struct sh_wdt {
  82         void __iomem            *base;
  83         struct device           *dev;
  84
  85         struct timer_list       timer;
  86
  87         unsigned long           enabled;
  88         char                    expect_close;
  89 };
  90
  91 static void sh_wdt_start(struct sh_wdt *wdt)
  92 {
  93         unsigned long flags;
  94         u8 csr;
  95
  96         spin_lock_irqsave(&shwdt_lock, flags);
  97
  98         next_heartbeat = jiffies + (heartbeat * HZ);
  99         mod_timer(&wdt->timer, next_ping_period(clock_division_ratio));
 100
 101         csr = sh_wdt_read_csr();
 102         csr |= WTCSR_WT | clock_division_ratio;
 103         sh_wdt_write_csr(csr);
 104
 105         sh_wdt_write_cnt(0);
 106
 107         /*
 108          * These processors have a bit of an inconsistent initialization
 109          * process.. starting with SH-3, RSTS was moved to WTCSR, and the
 110          * RSTCSR register was removed.
 111          *
 112          * On the SH-2 however, in addition with bits being in different
 113          * locations, we must deal with RSTCSR outright..
 114          */
 115         csr = sh_wdt_read_csr();
 116         csr |= WTCSR_TME;
 117         csr &= ~WTCSR_RSTS;
 118         sh_wdt_write_csr(csr);
 119
 120 #ifdef CONFIG_CPU_SH2
 121         csr = sh_wdt_read_rstcsr();
 122         csr &= ~RSTCSR_RSTS;
 123         sh_wdt_write_rstcsr(csr);
 124 #endif
 125         spin_unlock_irqrestore(&shwdt_lock, flags);
 126 }
 127
 128 static void sh_wdt_stop(struct sh_wdt *wdt)
 129 {
 130         unsigned long flags;
 131         u8 csr;
 132
 133         spin_lock_irqsave(&shwdt_lock, flags);
 134
 135         del_timer(&wdt->timer);
 136
 137         csr = sh_wdt_read_csr();
 138         csr &= ~WTCSR_TME;
 139         sh_wdt_write_csr(csr);
 140
 141         spin_unlock_irqrestore(&shwdt_lock, flags);
 142 }
 143
 144 static inline void sh_wdt_keepalive(struct sh_wdt *wdt)
 145 {
 146         unsigned long flags;
 147
 148         spin_lock_irqsave(&shwdt_lock, flags);
 149         next_heartbeat = jiffies + (heartbeat * HZ);
 150         spin_unlock_irqrestore(&shwdt_lock, flags);
 151 }
 152
 153 static int sh_wdt_set_heartbeat(int t)
 154 {
 155         unsigned long flags;
 156
 157         if (unlikely(t < 1 || t > 3600)) /* arbitrary upper limit */
 158                 return -EINVAL;
 159
 160         spin_lock_irqsave(&shwdt_lock, flags);
 161         heartbeat = t;
 162         spin_unlock_irqrestore(&shwdt_lock, flags);
 163         return 0;
 164 }
 165
 166 static void sh_wdt_ping(unsigned long data)
 167 {
 168         struct sh_wdt *wdt = (struct sh_wdt *)data;
 169         unsigned long flags;
 170
 171         spin_lock_irqsave(&shwdt_lock, flags);
 172         if (time_before(jiffies, next_heartbeat)) {
 173                 u8 csr;
 174
 175                 csr = sh_wdt_read_csr();
 176                 csr &= ~WTCSR_IOVF;
 177                 sh_wdt_write_csr(csr);
 178
 179                 sh_wdt_write_cnt(0);
 180
 181                 mod_timer(&wdt->timer, next_ping_period(clock_division_ratio));
 182         } else
 183                 dev_warn(wdt->dev, "Heartbeat lost! Will not ping "
 184                          "the watchdog\n");
 185         spin_unlock_irqrestore(&shwdt_lock, flags);
 186 }
 187
 188 static int sh_wdt_open(struct inode *inode, struct file *file)
 189 {
 190         struct sh_wdt *wdt = platform_get_drvdata(sh_wdt_dev);
 191
 192         if (test_and_set_bit(0, &wdt->enabled))
 193                 return -EBUSY;
 194         if (nowayout)
 195                 __module_get(THIS_MODULE);
 196
 197         file->private_data = wdt;
 198
 199         sh_wdt_start(wdt);
 200
 201         return nonseekable_open(inode, file);
 202 }
 203
 204 static int sh_wdt_close(struct inode *inode, struct file *file)
 205 {
 206         struct sh_wdt *wdt = file->private_data;
 207
 208         if (wdt->expect_close == 42) {
 209                 sh_wdt_stop(wdt);
 210         } else {
 211                 dev_crit(wdt->dev, "Unexpected close, not "
 212                          "stopping watchdog!\n");
 213                 sh_wdt_keepalive(wdt);
 214         }
 215
 216         clear_bit(0, &wdt->enabled);
 217         wdt->expect_close = 0;
 218
 219         return 0;
 220 }
 221
 222 static ssize_t sh_wdt_write(struct file *file, const char *buf,
 223                             size_t count, loff_t *ppos)
 224 {
 225         struct sh_wdt *wdt = file->private_data;
 226
 227         if (count) {
 228                 if (!nowayout) {
 229                         size_t i;
 230
 231                         wdt->expect_close = 0;
 232
 233                         for (i = 0; i != count; i++) {
 234                                 char c;
 235                                 if (get_user(c, buf + i))
 236                                         return -EFAULT;
 237                                 if (c == 'V')
 238                                         wdt->expect_close = 42;
 239                         }
 240                 }
 241                 sh_wdt_keepalive(wdt);
 242         }
 243
 244         return count;
 245 }
 246
 247 static long sh_wdt_ioctl(struct file *file, unsigned int cmd,
 248                                                         unsigned long arg)
 249 {
 250         struct sh_wdt *wdt = file->private_data;
 251         int new_heartbeat;
 252         int options, retval = -EINVAL;
 253
 254         switch (cmd) {
 255         case WDIOC_GETSUPPORT:
 256                 return copy_to_user((struct watchdog_info *)arg,
 257                           &sh_wdt_info, sizeof(sh_wdt_info)) ? -EFAULT : 0;
 258         case WDIOC_GETSTATUS:
 259         case WDIOC_GETBOOTSTATUS:
 260                 return put_user(0, (int *)arg);
 261         case WDIOC_SETOPTIONS:
 262                 if (get_user(options, (int *)arg))
 263                         return -EFAULT;
 264
 265                 if (options & WDIOS_DISABLECARD) {
 266                         sh_wdt_stop(wdt);
 267                         retval = 0;
 268                 }
 269
 270                 if (options & WDIOS_ENABLECARD) {
 271                         sh_wdt_start(wdt);
 272                         retval = 0;
 273                 }
 274
 275                 return retval;
 276         case WDIOC_KEEPALIVE:
 277                 sh_wdt_keepalive(wdt);
 278                 return 0;
 279         case WDIOC_SETTIMEOUT:
 280                 if (get_user(new_heartbeat, (int *)arg))
 281                         return -EFAULT;
 282
 283                 if (sh_wdt_set_heartbeat(new_heartbeat))
 284                         return -EINVAL;
 285
 286                 sh_wdt_keepalive(wdt);
 287                 /* Fall */
 288         case WDIOC_GETTIMEOUT:
 289                 return put_user(heartbeat, (int *)arg);
 290         default:
 291                 return -ENOTTY;
 292         }
 293         return 0;
 294 }
 295
 296 static int sh_wdt_notify_sys(struct notifier_block *this,
 297                              unsigned long code, void *unused)
 298 {
 299         struct sh_wdt *wdt = platform_get_drvdata(sh_wdt_dev);
 300
 301         if (code == SYS_DOWN || code == SYS_HALT)
 302                 sh_wdt_stop(wdt);
 303
 304         return NOTIFY_DONE;
 305 }
 306
 307 static const struct file_operations sh_wdt_fops = {
 308         .owner          = THIS_MODULE,
 309         .llseek         = no_llseek,
 310         .write          = sh_wdt_write,
 311         .unlocked_ioctl = sh_wdt_ioctl,
 312         .open           = sh_wdt_open,
 313         .release        = sh_wdt_close,
 314 };
 315
 316 static const struct watchdog_info sh_wdt_info = {
 317         .options                = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 318                                   WDIOF_MAGICCLOSE,
 319         .firmware_version       = 1,
 320         .identity               = "SH WDT",
 321 };
 322
 323 static struct notifier_block sh_wdt_notifier = {
 324         .notifier_call          = sh_wdt_notify_sys,
 325 };
 326
 327 static struct miscdevice sh_wdt_miscdev = {
 328         .minor          = WATCHDOG_MINOR,
 329         .name           = "watchdog",
 330         .fops           = &sh_wdt_fops,
 331 };
 332
 333 static int __devinit sh_wdt_probe(struct platform_device *pdev)
 334 {
 335         struct sh_wdt *wdt;
 336         struct resource *res;
 337         int rc;
 338
 339         /*
 340          * As this driver only covers the global watchdog case, reject
 341          * any attempts to register per-CPU watchdogs.
 342          */
 343         if (pdev->id != -1)
 344                 return -EINVAL;
 345
 346         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 347         if (unlikely(!res))
 348                 return -EINVAL;
 349
 350         if (!devm_request_mem_region(&pdev->dev, res->start,
 351                                      resource_size(res), DRV_NAME))
 352                 return -EBUSY;
 353
 354         wdt = devm_kzalloc(&pdev->dev, sizeof(struct sh_wdt), GFP_KERNEL);
 355         if (unlikely(!wdt)) {
 356                 rc = -ENOMEM;
 357                 goto out_release;
 358         }
 359
 360         wdt->dev = &pdev->dev;
 361
 362         wdt->base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
 363         if (unlikely(!wdt->base)) {
 364                 rc = -ENXIO;
 365                 goto out_err;
 366         }
 367
 368         rc = register_reboot_notifier(&sh_wdt_notifier);
 369         if (unlikely(rc)) {
 370                 dev_err(&pdev->dev,
 371                         "Can't register reboot notifier (err=%d)\n", rc);
 372                 goto out_unmap;
 373         }
 374
 375         sh_wdt_miscdev.parent = wdt->dev;
 376
 377         rc = misc_register(&sh_wdt_miscdev);
 378         if (unlikely(rc)) {
 379                 dev_err(&pdev->dev,
 380                         "Can't register miscdev on minor=%d (err=%d)\n",
 381                                                 sh_wdt_miscdev.minor, rc);
 382                 goto out_unreg;
 383         }
 384
 385         init_timer(&wdt->timer);
 386         wdt->timer.function     = sh_wdt_ping;
 387         wdt->timer.data         = (unsigned long)wdt;
 388         wdt->timer.expires      = next_ping_period(clock_division_ratio);
 389
 390         platform_set_drvdata(pdev, wdt);
 391         sh_wdt_dev = pdev;
 392
 393         dev_info(&pdev->dev, "initialized.\n");
 394
 395         return 0;
 396
 397 out_unreg:
 398         unregister_reboot_notifier(&sh_wdt_notifier);
 399 out_unmap:
 400         devm_iounmap(&pdev->dev, wdt->base);
 401 out_err:
 402         devm_kfree(&pdev->dev, wdt);
 403 out_release:
 404         devm_release_mem_region(&pdev->dev, res->start, resource_size(res));
 405
 406         return rc;
 407 }
 408
 409 static int __devexit sh_wdt_remove(struct platform_device *pdev)
 410 {
 411         struct sh_wdt *wdt = platform_get_drvdata(pdev);
 412         struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 413
 414         platform_set_drvdata(pdev, NULL);
 415
 416         misc_deregister(&sh_wdt_miscdev);
 417
 418         sh_wdt_dev = NULL;
 419
 420         unregister_reboot_notifier(&sh_wdt_notifier);
 421         devm_release_mem_region(&pdev->dev, res->start, resource_size(res));
 422         devm_iounmap(&pdev->dev, wdt->base);
 423         devm_kfree(&pdev->dev, wdt);
 424
 425         return 0;
 426 }
 427
 428 static struct platform_driver sh_wdt_driver = {
 429         .driver         = {
 430                 .name   = DRV_NAME,
 431                 .owner  = THIS_MODULE,
 432         },
 433
 434         .probe  = sh_wdt_probe,
 435         .remove = __devexit_p(sh_wdt_remove),
 436 };
 437
 438 static int __init sh_wdt_init(void)
 439 {
 440         int rc;
 441
 442         if (unlikely(clock_division_ratio < 0x5 ||
 443                      clock_division_ratio > 0x7)) {
 444                 clock_division_ratio = WTCSR_CKS_4096;
 445
 446                 pr_info("divisor must be 0x5<=x<=0x7, using %d\n",
 447                         clock_division_ratio);
 448         }
 449
 450         rc = sh_wdt_set_heartbeat(heartbeat);
 451         if (unlikely(rc)) {
 452                 heartbeat = WATCHDOG_HEARTBEAT;
 453
 454                 pr_info("heartbeat value must be 1<=x<=3600, using %d\n",
 455                         heartbeat);
 456         }
 457
 458         pr_info("configured with heartbeat=%d sec (nowayout=%d)\n",
 459                 heartbeat, nowayout);
 460
 461         return platform_driver_register(&sh_wdt_driver);
 462 }
 463
 464 static void __exit sh_wdt_exit(void)
 465 {
 466         platform_driver_unregister(&sh_wdt_driver);
 467 }
 468 module_init(sh_wdt_init);
 469 module_exit(sh_wdt_exit);
 470
 471 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
 472 MODULE_DESCRIPTION("SuperH watchdog driver");
 473 MODULE_LICENSE("GPL");
 474 MODULE_ALIAS("platform:" DRV_NAME);
 475 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 476
 477 module_param(clock_division_ratio, int, 0);
 478 MODULE_PARM_DESC(clock_division_ratio,
 479         "Clock division ratio. Valid ranges are from 0x5 (1.31ms) "
 480         "to 0x7 (5.25ms). (default=" __MODULE_STRING(WTCSR_CKS_4096) ")");
 481
 482 module_param(heartbeat, int, 0);
 483 MODULE_PARM_DESC(heartbeat,
 484         "Watchdog heartbeat in seconds. (1 <= heartbeat <= 3600, default="
 485                                 __MODULE_STRING(WATCHDOG_HEARTBEAT) ")");
 486
 487 module_param(nowayout, bool, 0);
 488 MODULE_PARM_DESC(nowayout,
 489         "Watchdog cannot be stopped once started (default="
 490                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");