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