drivers/char/watchdog/s3c2410_wdt.c

   1 /* linux/drivers/char/watchdog/s3c2410_wdt.c
   2  *
   3  * Copyright (c) 2004 Simtec Electronics
   4  *      Ben Dooks <ben@simtec.co.uk>
   5  *
   6  * S3C2410 Watchdog Timer Support
   7  *
   8  * Based on, softdog.c by Alan Cox,
   9  *     (c) Copyright 1996 Alan Cox <alan@redhat.com>
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  24  *
  25  * Changelog:
  26  *      05-Oct-2004     BJD     Added semaphore init to stop crashes on open
  27  *                              Fixed tmr_count / wdt_count confusion
  28  *                              Added configurable debug
  29  *
  30  *      11-Jan-2005     BJD     Fixed divide-by-2 in timeout code
  31  *
  32  *      25-Jan-2005     DA      Added suspend/resume support
  33  *
  34  *      10-Mar-2005     LCVR    Changed S3C2410_VA to S3C24XX_VA
  35 */
  36
  37 #include <linux/module.h>
  38 #include <linux/moduleparam.h>
  39 #include <linux/config.h>
  40 #include <linux/types.h>
  41 #include <linux/timer.h>
  42 #include <linux/miscdevice.h>
  43 #include <linux/watchdog.h>
  44 #include <linux/fs.h>
  45 #include <linux/notifier.h>
  46 #include <linux/reboot.h>
  47 #include <linux/init.h>
  48 #include <linux/device.h>
  49 #include <linux/interrupt.h>
  50
  51 #include <asm/uaccess.h>
  52 #include <asm/io.h>
  53
  54 #include <asm/arch/map.h>
  55 #include <asm/hardware/clock.h>
  56
  57 #undef S3C24XX_VA_WATCHDOG
  58 #define S3C24XX_VA_WATCHDOG (0)
  59
  60 #include <asm/arch/regs-watchdog.h>
  61
  62 #define PFX "s3c2410-wdt: "
  63
  64 #define CONFIG_S3C2410_WATCHDOG_ATBOOT          (0)
  65 #define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME    (15)
  66
  67 static int nowayout = WATCHDOG_NOWAYOUT;
  68 static int tmr_margin   = CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME;
  69 static int tmr_atboot   = CONFIG_S3C2410_WATCHDOG_ATBOOT;
  70 static int soft_noboot  = 0;
  71 static int debug        = 0;
  72
  73 module_param(tmr_margin,  int, 0);
  74 module_param(tmr_atboot,  int, 0);
  75 module_param(nowayout,    int, 0);
  76 module_param(soft_noboot, int, 0);
  77 module_param(debug,       int, 0);
  78
  79 MODULE_PARM_DESC(tmr_margin, "Watchdog tmr_margin in seconds. default=" __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME) ")");
  80
  81 MODULE_PARM_DESC(tmr_atboot, "Watchdog is started at boot time if set to 1, default=" __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_ATBOOT));
  82
  83 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
  84
  85 MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)");
  86
  87 MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug, (default 0)");
  88
  89
  90 typedef enum close_state {
  91         CLOSE_STATE_NOT,
  92         CLOSE_STATE_ALLOW=0x4021
  93 } close_state_t;
  94
  95 static DECLARE_MUTEX(open_lock);
  96
  97 static struct resource  *wdt_mem;
  98 static struct resource  *wdt_irq;
  99 static struct clk       *wdt_clock;
 100 static void __iomem     *wdt_base;
 101 static unsigned int      wdt_count;
 102 static close_state_t     allow_close;
 103
 104 /* watchdog control routines */
 105
 106 #define DBG(msg...) do { \
 107         if (debug) \
 108                 printk(KERN_INFO msg); \
 109         } while(0)
 110
 111 /* functions */
 112
 113 static int s3c2410wdt_keepalive(void)
 114 {
 115         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 116         return 0;
 117 }
 118
 119 static int s3c2410wdt_stop(void)
 120 {
 121         unsigned long wtcon;
 122
 123         wtcon = readl(wdt_base + S3C2410_WTCON);
 124         wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
 125         writel(wtcon, wdt_base + S3C2410_WTCON);
 126
 127         return 0;
 128 }
 129
 130 static int s3c2410wdt_start(void)
 131 {
 132         unsigned long wtcon;
 133
 134         s3c2410wdt_stop();
 135
 136         wtcon = readl(wdt_base + S3C2410_WTCON);
 137         wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;
 138
 139         if (soft_noboot) {
 140                 wtcon |= S3C2410_WTCON_INTEN;
 141                 wtcon &= ~S3C2410_WTCON_RSTEN;
 142         } else {
 143                 wtcon &= ~S3C2410_WTCON_INTEN;
 144                 wtcon |= S3C2410_WTCON_RSTEN;
 145         }
 146
 147         DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
 148             __FUNCTION__, wdt_count, wtcon);
 149
 150         writel(wdt_count, wdt_base + S3C2410_WTDAT);
 151         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 152         writel(wtcon, wdt_base + S3C2410_WTCON);
 153
 154         return 0;
 155 }
 156
 157 static int s3c2410wdt_set_heartbeat(int timeout)
 158 {
 159         unsigned int freq = clk_get_rate(wdt_clock);
 160         unsigned int count;
 161         unsigned int divisor = 1;
 162         unsigned long wtcon;
 163
 164         if (timeout < 1)
 165                 return -EINVAL;
 166
 167         freq /= 128;
 168         count = timeout * freq;
 169
 170         DBG("%s: count=%d, timeout=%d, freq=%d\n",
 171             __FUNCTION__, count, timeout, freq);
 172
 173         /* if the count is bigger than the watchdog register,
 174            then work out what we need to do (and if) we can
 175            actually make this value
 176         */
 177
 178         if (count >= 0x10000) {
 179                 for (divisor = 1; divisor <= 0x100; divisor++) {
 180                         if ((count / divisor) < 0x10000)
 181                                 break;
 182                 }
 183
 184                 if ((count / divisor) >= 0x10000) {
 185                         printk(KERN_ERR PFX "timeout %d too big\n", timeout);
 186                         return -EINVAL;
 187                 }
 188         }
 189
 190         tmr_margin = timeout;
 191
 192         DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
 193             __FUNCTION__, timeout, divisor, count, count/divisor);
 194
 195         count /= divisor;
 196         wdt_count = count;
 197
 198         /* update the pre-scaler */
 199         wtcon = readl(wdt_base + S3C2410_WTCON);
 200         wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
 201         wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);
 202
 203         writel(count, wdt_base + S3C2410_WTDAT);
 204         writel(wtcon, wdt_base + S3C2410_WTCON);
 205
 206         return 0;
 207 }
 208
 209 /*
 210  *      /dev/watchdog handling
 211  */
 212
 213 static int s3c2410wdt_open(struct inode *inode, struct file *file)
 214 {
 215         if(down_trylock(&open_lock))
 216                 return -EBUSY;
 217
 218         if (nowayout) {
 219                 __module_get(THIS_MODULE);
 220         } else {
 221                 allow_close = CLOSE_STATE_ALLOW;
 222         }
 223
 224         /* start the timer */
 225         s3c2410wdt_start();
 226         return nonseekable_open(inode, file);
 227 }
 228
 229 static int s3c2410wdt_release(struct inode *inode, struct file *file)
 230 {
 231         /*
 232          *      Shut off the timer.
 233          *      Lock it in if it's a module and we set nowayout
 234          */
 235         if (allow_close == CLOSE_STATE_ALLOW) {
 236                 s3c2410wdt_stop();
 237         } else {
 238                 printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
 239                 s3c2410wdt_keepalive();
 240         }
 241
 242         allow_close = CLOSE_STATE_NOT;
 243         up(&open_lock);
 244         return 0;
 245 }
 246
 247 static ssize_t s3c2410wdt_write(struct file *file, const char __user *data,
 248                                 size_t len, loff_t *ppos)
 249 {
 250         /*
 251          *      Refresh the timer.
 252          */
 253         if(len) {
 254                 if (!nowayout) {
 255                         size_t i;
 256
 257                         /* In case it was set long ago */
 258                         allow_close = CLOSE_STATE_NOT;
 259
 260                         for (i = 0; i != len; i++) {
 261                                 char c;
 262
 263                                 if (get_user(c, data + i))
 264                                         return -EFAULT;
 265                                 if (c == 'V')
 266                                         allow_close = CLOSE_STATE_ALLOW;
 267                         }
 268                 }
 269
 270                 s3c2410wdt_keepalive();
 271         }
 272         return len;
 273 }
 274
 275 #define OPTIONS WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE
 276
 277 static struct watchdog_info s3c2410_wdt_ident = {
 278         .options          =     OPTIONS,
 279         .firmware_version =     0,
 280         .identity         =     "S3C2410 Watchdog",
 281 };
 282
 283
 284 static int s3c2410wdt_ioctl(struct inode *inode, struct file *file,
 285         unsigned int cmd, unsigned long arg)
 286 {
 287         void __user *argp = (void __user *)arg;
 288         int __user *p = argp;
 289         int new_margin;
 290
 291         switch (cmd) {
 292                 default:
 293                         return -ENOIOCTLCMD;
 294
 295                 case WDIOC_GETSUPPORT:
 296                         return copy_to_user(argp, &s3c2410_wdt_ident,
 297                                 sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0;
 298
 299                 case WDIOC_GETSTATUS:
 300                 case WDIOC_GETBOOTSTATUS:
 301                         return put_user(0, p);
 302
 303                 case WDIOC_KEEPALIVE:
 304                         s3c2410wdt_keepalive();
 305                         return 0;
 306
 307                 case WDIOC_SETTIMEOUT:
 308                         if (get_user(new_margin, p))
 309                                 return -EFAULT;
 310
 311                         if (s3c2410wdt_set_heartbeat(new_margin))
 312                                 return -EINVAL;
 313
 314                         s3c2410wdt_keepalive();
 315                         return put_user(tmr_margin, p);
 316
 317                 case WDIOC_GETTIMEOUT:
 318                         return put_user(tmr_margin, p);
 319         }
 320 }
 321
 322 /*
 323  *      Notifier for system down
 324  */
 325
 326 static int s3c2410wdt_notify_sys(struct notifier_block *this, unsigned long code,
 327                               void *unused)
 328 {
 329         if(code==SYS_DOWN || code==SYS_HALT) {
 330                 /* Turn the WDT off */
 331                 s3c2410wdt_stop();
 332         }
 333         return NOTIFY_DONE;
 334 }
 335
 336 /* kernel interface */
 337
 338 static struct file_operations s3c2410wdt_fops = {
 339         .owner          = THIS_MODULE,
 340         .llseek         = no_llseek,
 341         .write          = s3c2410wdt_write,
 342         .ioctl          = s3c2410wdt_ioctl,
 343         .open           = s3c2410wdt_open,
 344         .release        = s3c2410wdt_release,
 345 };
 346
 347 static struct miscdevice s3c2410wdt_miscdev = {
 348         .minor          = WATCHDOG_MINOR,
 349         .name           = "watchdog",
 350         .fops           = &s3c2410wdt_fops,
 351 };
 352
 353 static struct notifier_block s3c2410wdt_notifier = {
 354         .notifier_call  = s3c2410wdt_notify_sys,
 355 };
 356
 357 /* interrupt handler code */
 358
 359 static irqreturn_t s3c2410wdt_irq(int irqno, void *param,
 360                                   struct pt_regs *regs)
 361 {
 362         printk(KERN_INFO PFX "Watchdog timer expired!\n");
 363
 364         s3c2410wdt_keepalive();
 365         return IRQ_HANDLED;
 366 }
 367 /* device interface */
 368
 369 static int s3c2410wdt_probe(struct device *dev)
 370 {
 371         struct platform_device *pdev = to_platform_device(dev);
 372         struct resource *res;
 373         int started = 0;
 374         int ret;
 375         int size;
 376
 377         DBG("%s: probe=%p, device=%p\n", __FUNCTION__, pdev, dev);
 378
 379         /* get the memory region for the watchdog timer */
 380
 381         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 382         if (res == NULL) {
 383                 printk(KERN_INFO PFX "failed to get memory region resouce\n");
 384                 return -ENOENT;
 385         }
 386
 387         size = (res->end-res->start)+1;
 388         wdt_mem = request_mem_region(res->start, size, pdev->name);
 389         if (wdt_mem == NULL) {
 390                 printk(KERN_INFO PFX "failed to get memory region\n");
 391                 return -ENOENT;
 392         }
 393
 394         wdt_base = ioremap(res->start, size);
 395         if (wdt_base == 0) {
 396                 printk(KERN_INFO PFX "failed to ioremap() region\n");
 397                 return -EINVAL;
 398         }
 399
 400         DBG("probe: mapped wdt_base=%p\n", wdt_base);
 401
 402         res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 403         if (res == NULL) {
 404                 printk(KERN_INFO PFX "failed to get irq resource\n");
 405                 return -ENOENT;
 406         }
 407
 408         ret = request_irq(res->start, s3c2410wdt_irq, 0, pdev->name, dev);
 409         if (ret != 0) {
 410                 printk(KERN_INFO PFX "failed to install irq (%d)\n", ret);
 411                 return ret;
 412         }
 413
 414         wdt_clock = clk_get(dev, "watchdog");
 415         if (wdt_clock == NULL) {
 416                 printk(KERN_INFO PFX "failed to find watchdog clock source\n");
 417                 return -ENOENT;
 418         }
 419
 420         clk_use(wdt_clock);
 421         clk_enable(wdt_clock);
 422
 423         /* see if we can actually set the requested timer margin, and if
 424          * not, try the default value */
 425
 426         if (s3c2410wdt_set_heartbeat(tmr_margin)) {
 427                 started = s3c2410wdt_set_heartbeat(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 428
 429                 if (started == 0) {
 430                         printk(KERN_INFO PFX "tmr_margin value out of range, default %d used\n",
 431                                CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 432                 } else {
 433                         printk(KERN_INFO PFX "default timer value is out of range, cannot start\n");
 434                 }
 435         }
 436
 437         ret = register_reboot_notifier(&s3c2410wdt_notifier);
 438         if (ret) {
 439                 printk (KERN_ERR PFX "cannot register reboot notifier (%d)\n",
 440                         ret);
 441                 return ret;
 442         }
 443
 444         ret = misc_register(&s3c2410wdt_miscdev);
 445         if (ret) {
 446                 printk (KERN_ERR PFX "cannot register miscdev on minor=%d (%d)\n",
 447                         WATCHDOG_MINOR, ret);
 448                 unregister_reboot_notifier(&s3c2410wdt_notifier);
 449                 return ret;
 450         }
 451
 452         if (tmr_atboot && started == 0) {
 453                 printk(KERN_INFO PFX "Starting Watchdog Timer\n");
 454                 s3c2410wdt_start();
 455         }
 456
 457         return 0;
 458 }
 459
 460 static int s3c2410wdt_remove(struct device *dev)
 461 {
 462         if (wdt_mem != NULL) {
 463                 release_resource(wdt_mem);
 464                 kfree(wdt_mem);
 465                 wdt_mem = NULL;
 466         }
 467
 468         if (wdt_irq != NULL) {
 469                 free_irq(wdt_irq->start, dev);
 470                 wdt_irq = NULL;
 471         }
 472
 473         if (wdt_clock != NULL) {
 474                 clk_disable(wdt_clock);
 475                 clk_unuse(wdt_clock);
 476                 clk_put(wdt_clock);
 477                 wdt_clock = NULL;
 478         }
 479
 480         misc_deregister(&s3c2410wdt_miscdev);
 481         return 0;
 482 }
 483
 484 #ifdef CONFIG_PM
 485
 486 static unsigned long wtcon_save;
 487 static unsigned long wtdat_save;
 488
 489 static int s3c2410wdt_suspend(struct device *dev, u32 state, u32 level)
 490 {
 491         if (level == SUSPEND_POWER_DOWN) {
 492                 /* Save watchdog state, and turn it off. */
 493                 wtcon_save = readl(wdt_base + S3C2410_WTCON);
 494                 wtdat_save = readl(wdt_base + S3C2410_WTDAT);
 495
 496                 /* Note that WTCNT doesn't need to be saved. */
 497                 s3c2410wdt_stop();
 498         }
 499
 500         return 0;
 501 }
 502
 503 static int s3c2410wdt_resume(struct device *dev, u32 level)
 504 {
 505         if (level == RESUME_POWER_ON) {
 506                 /* Restore watchdog state. */
 507
 508                 writel(wtdat_save, wdt_base + S3C2410_WTDAT);
 509                 writel(wtdat_save, wdt_base + S3C2410_WTCNT); /* Reset count */
 510                 writel(wtcon_save, wdt_base + S3C2410_WTCON);
 511
 512                 printk(KERN_INFO PFX "watchdog %sabled\n",
 513                        (wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
 514         }
 515
 516         return 0;
 517 }
 518
 519 #else
 520 #define s3c2410wdt_suspend NULL
 521 #define s3c2410wdt_resume  NULL
 522 #endif /* CONFIG_PM */
 523
 524
 525 static struct device_driver s3c2410wdt_driver = {
 526         .name           = "s3c2410-wdt",
 527         .bus            = &platform_bus_type,
 528         .probe          = s3c2410wdt_probe,
 529         .remove         = s3c2410wdt_remove,
 530         .suspend        = s3c2410wdt_suspend,
 531         .resume         = s3c2410wdt_resume,
 532 };
 533
 534
 535 static char banner[] __initdata = KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n";
 536
 537 static int __init watchdog_init(void)
 538 {
 539         printk(banner);
 540         return driver_register(&s3c2410wdt_driver);
 541 }
 542
 543 static void __exit watchdog_exit(void)
 544 {
 545         driver_unregister(&s3c2410wdt_driver);
 546         unregister_reboot_notifier(&s3c2410wdt_notifier);
 547 }
 548
 549 module_init(watchdog_init);
 550 module_exit(watchdog_exit);
 551
 552 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "
 553               "Dimitry Andric <dimitry.andric@tomtom.com>");
 554 MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
 555 MODULE_LICENSE("GPL");
 556 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);