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   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  *                              Replaced reboot notifier with .shutdown method
  34  *
  35  *      10-Mar-2005     LCVR    Changed S3C2410_VA to S3C24XX_VA
  36 */
  37
  38 #include <linux/module.h>
  39 #include <linux/moduleparam.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/init.h>
  46 #include <linux/platform_device.h>
  47 #include <linux/interrupt.h>
  48 #include <linux/clk.h>
  49
  50 #include <asm/uaccess.h>
  51 #include <asm/io.h>
  52
  53 #include <asm/arch/map.h>
  54
  55 #undef S3C24XX_VA_WATCHDOG
  56 #define S3C24XX_VA_WATCHDOG (0)
  57
  58 #include <asm/arch/regs-watchdog.h>
  59
  60 #define PFX "s3c2410-wdt: "
  61
  62 #define CONFIG_S3C2410_WATCHDOG_ATBOOT          (0)
  63 #define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME    (15)
  64
  65 static int nowayout     = WATCHDOG_NOWAYOUT;
  66 static int tmr_margin   = CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME;
  67 static int tmr_atboot   = CONFIG_S3C2410_WATCHDOG_ATBOOT;
  68 static int soft_noboot  = 0;
  69 static int debug        = 0;
  70
  71 module_param(tmr_margin,  int, 0);
  72 module_param(tmr_atboot,  int, 0);
  73 module_param(nowayout,    int, 0);
  74 module_param(soft_noboot, int, 0);
  75 module_param(debug,       int, 0);
  76
  77 MODULE_PARM_DESC(tmr_margin, "Watchdog tmr_margin in seconds. default=" __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME) ")");
  78
  79 MODULE_PARM_DESC(tmr_atboot, "Watchdog is started at boot time if set to 1, default=" __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_ATBOOT));
  80
  81 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
  82
  83 MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)");
  84
  85 MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug, (default 0)");
  86
  87
  88 typedef enum close_state {
  89         CLOSE_STATE_NOT,
  90         CLOSE_STATE_ALLOW=0x4021
  91 } close_state_t;
  92
  93 static DECLARE_MUTEX(open_lock);
  94
  95 static struct resource  *wdt_mem;
  96 static struct resource  *wdt_irq;
  97 static struct clk       *wdt_clock;
  98 static void __iomem     *wdt_base;
  99 static unsigned int      wdt_count;
 100 static close_state_t     allow_close;
 101
 102 /* watchdog control routines */
 103
 104 #define DBG(msg...) do { \
 105         if (debug) \
 106                 printk(KERN_INFO msg); \
 107         } while(0)
 108
 109 /* functions */
 110
 111 static int s3c2410wdt_keepalive(void)
 112 {
 113         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 114         return 0;
 115 }
 116
 117 static int s3c2410wdt_stop(void)
 118 {
 119         unsigned long wtcon;
 120
 121         wtcon = readl(wdt_base + S3C2410_WTCON);
 122         wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
 123         writel(wtcon, wdt_base + S3C2410_WTCON);
 124
 125         return 0;
 126 }
 127
 128 static int s3c2410wdt_start(void)
 129 {
 130         unsigned long wtcon;
 131
 132         s3c2410wdt_stop();
 133
 134         wtcon = readl(wdt_base + S3C2410_WTCON);
 135         wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;
 136
 137         if (soft_noboot) {
 138                 wtcon |= S3C2410_WTCON_INTEN;
 139                 wtcon &= ~S3C2410_WTCON_RSTEN;
 140         } else {
 141                 wtcon &= ~S3C2410_WTCON_INTEN;
 142                 wtcon |= S3C2410_WTCON_RSTEN;
 143         }
 144
 145         DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
 146             __FUNCTION__, wdt_count, wtcon);
 147
 148         writel(wdt_count, wdt_base + S3C2410_WTDAT);
 149         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 150         writel(wtcon, wdt_base + S3C2410_WTCON);
 151
 152         return 0;
 153 }
 154
 155 static int s3c2410wdt_set_heartbeat(int timeout)
 156 {
 157         unsigned int freq = clk_get_rate(wdt_clock);
 158         unsigned int count;
 159         unsigned int divisor = 1;
 160         unsigned long wtcon;
 161
 162         if (timeout < 1)
 163                 return -EINVAL;
 164
 165         freq /= 128;
 166         count = timeout * freq;
 167
 168         DBG("%s: count=%d, timeout=%d, freq=%d\n",
 169             __FUNCTION__, count, timeout, freq);
 170
 171         /* if the count is bigger than the watchdog register,
 172            then work out what we need to do (and if) we can
 173            actually make this value
 174         */
 175
 176         if (count >= 0x10000) {
 177                 for (divisor = 1; divisor <= 0x100; divisor++) {
 178                         if ((count / divisor) < 0x10000)
 179                                 break;
 180                 }
 181
 182                 if ((count / divisor) >= 0x10000) {
 183                         printk(KERN_ERR PFX "timeout %d too big\n", timeout);
 184                         return -EINVAL;
 185                 }
 186         }
 187
 188         tmr_margin = timeout;
 189
 190         DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
 191             __FUNCTION__, timeout, divisor, count, count/divisor);
 192
 193         count /= divisor;
 194         wdt_count = count;
 195
 196         /* update the pre-scaler */
 197         wtcon = readl(wdt_base + S3C2410_WTCON);
 198         wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
 199         wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);
 200
 201         writel(count, wdt_base + S3C2410_WTDAT);
 202         writel(wtcon, wdt_base + S3C2410_WTCON);
 203
 204         return 0;
 205 }
 206
 207 /*
 208  *      /dev/watchdog handling
 209  */
 210
 211 static int s3c2410wdt_open(struct inode *inode, struct file *file)
 212 {
 213         if(down_trylock(&open_lock))
 214                 return -EBUSY;
 215
 216         if (nowayout)
 217                 __module_get(THIS_MODULE);
 218
 219         allow_close = CLOSE_STATE_NOT;
 220
 221         /* start the timer */
 222         s3c2410wdt_start();
 223         return nonseekable_open(inode, file);
 224 }
 225
 226 static int s3c2410wdt_release(struct inode *inode, struct file *file)
 227 {
 228         /*
 229          *      Shut off the timer.
 230          *      Lock it in if it's a module and we set nowayout
 231          */
 232
 233         if (allow_close == CLOSE_STATE_ALLOW) {
 234                 s3c2410wdt_stop();
 235         } else {
 236                 printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
 237                 s3c2410wdt_keepalive();
 238         }
 239
 240         allow_close = CLOSE_STATE_NOT;
 241         up(&open_lock);
 242         return 0;
 243 }
 244
 245 static ssize_t s3c2410wdt_write(struct file *file, const char __user *data,
 246                                 size_t len, loff_t *ppos)
 247 {
 248         /*
 249          *      Refresh the timer.
 250          */
 251         if(len) {
 252                 if (!nowayout) {
 253                         size_t i;
 254
 255                         /* In case it was set long ago */
 256                         allow_close = CLOSE_STATE_NOT;
 257
 258                         for (i = 0; i != len; i++) {
 259                                 char c;
 260
 261                                 if (get_user(c, data + i))
 262                                         return -EFAULT;
 263                                 if (c == 'V')
 264                                         allow_close = CLOSE_STATE_ALLOW;
 265                         }
 266                 }
 267
 268                 s3c2410wdt_keepalive();
 269         }
 270         return len;
 271 }
 272
 273 #define OPTIONS WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE
 274
 275 static struct watchdog_info s3c2410_wdt_ident = {
 276         .options          =     OPTIONS,
 277         .firmware_version =     0,
 278         .identity         =     "S3C2410 Watchdog",
 279 };
 280
 281
 282 static int s3c2410wdt_ioctl(struct inode *inode, struct file *file,
 283         unsigned int cmd, unsigned long arg)
 284 {
 285         void __user *argp = (void __user *)arg;
 286         int __user *p = argp;
 287         int new_margin;
 288
 289         switch (cmd) {
 290                 default:
 291                         return -ENOTTY;
 292
 293                 case WDIOC_GETSUPPORT:
 294                         return copy_to_user(argp, &s3c2410_wdt_ident,
 295                                 sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0;
 296
 297                 case WDIOC_GETSTATUS:
 298                 case WDIOC_GETBOOTSTATUS:
 299                         return put_user(0, p);
 300
 301                 case WDIOC_KEEPALIVE:
 302                         s3c2410wdt_keepalive();
 303                         return 0;
 304
 305                 case WDIOC_SETTIMEOUT:
 306                         if (get_user(new_margin, p))
 307                                 return -EFAULT;
 308
 309                         if (s3c2410wdt_set_heartbeat(new_margin))
 310                                 return -EINVAL;
 311
 312                         s3c2410wdt_keepalive();
 313                         return put_user(tmr_margin, p);
 314
 315                 case WDIOC_GETTIMEOUT:
 316                         return put_user(tmr_margin, p);
 317         }
 318 }
 319
 320 /* kernel interface */
 321
 322 static const struct file_operations s3c2410wdt_fops = {
 323         .owner          = THIS_MODULE,
 324         .llseek         = no_llseek,
 325         .write          = s3c2410wdt_write,
 326         .ioctl          = s3c2410wdt_ioctl,
 327         .open           = s3c2410wdt_open,
 328         .release        = s3c2410wdt_release,
 329 };
 330
 331 static struct miscdevice s3c2410wdt_miscdev = {
 332         .minor          = WATCHDOG_MINOR,
 333         .name           = "watchdog",
 334         .fops           = &s3c2410wdt_fops,
 335 };
 336
 337 /* interrupt handler code */
 338
 339 static irqreturn_t s3c2410wdt_irq(int irqno, void *param,
 340                                   struct pt_regs *regs)
 341 {
 342         printk(KERN_INFO PFX "Watchdog timer expired!\n");
 343
 344         s3c2410wdt_keepalive();
 345         return IRQ_HANDLED;
 346 }
 347 /* device interface */
 348
 349 static int s3c2410wdt_probe(struct platform_device *pdev)
 350 {
 351         struct resource *res;
 352         int started = 0;
 353         int ret;
 354         int size;
 355
 356         DBG("%s: probe=%p\n", __FUNCTION__, pdev);
 357
 358         /* get the memory region for the watchdog timer */
 359
 360         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 361         if (res == NULL) {
 362                 printk(KERN_INFO PFX "failed to get memory region resouce\n");
 363                 return -ENOENT;
 364         }
 365
 366         size = (res->end-res->start)+1;
 367         wdt_mem = request_mem_region(res->start, size, pdev->name);
 368         if (wdt_mem == NULL) {
 369                 printk(KERN_INFO PFX "failed to get memory region\n");
 370                 return -ENOENT;
 371         }
 372
 373         wdt_base = ioremap(res->start, size);
 374         if (wdt_base == 0) {
 375                 printk(KERN_INFO PFX "failed to ioremap() region\n");
 376                 return -EINVAL;
 377         }
 378
 379         DBG("probe: mapped wdt_base=%p\n", wdt_base);
 380
 381         res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 382         if (res == NULL) {
 383                 printk(KERN_INFO PFX "failed to get irq resource\n");
 384                 return -ENOENT;
 385         }
 386
 387         ret = request_irq(res->start, s3c2410wdt_irq, 0, pdev->name, pdev);
 388         if (ret != 0) {
 389                 printk(KERN_INFO PFX "failed to install irq (%d)\n", ret);
 390                 return ret;
 391         }
 392
 393         wdt_clock = clk_get(&pdev->dev, "watchdog");
 394         if (wdt_clock == NULL) {
 395                 printk(KERN_INFO PFX "failed to find watchdog clock source\n");
 396                 return -ENOENT;
 397         }
 398
 399         clk_enable(wdt_clock);
 400
 401         /* see if we can actually set the requested timer margin, and if
 402          * not, try the default value */
 403
 404         if (s3c2410wdt_set_heartbeat(tmr_margin)) {
 405                 started = s3c2410wdt_set_heartbeat(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 406
 407                 if (started == 0) {
 408                         printk(KERN_INFO PFX "tmr_margin value out of range, default %d used\n",
 409                                CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 410                 } else {
 411                         printk(KERN_INFO PFX "default timer value is out of range, cannot start\n");
 412                 }
 413         }
 414
 415         ret = misc_register(&s3c2410wdt_miscdev);
 416         if (ret) {
 417                 printk (KERN_ERR PFX "cannot register miscdev on minor=%d (%d)\n",
 418                         WATCHDOG_MINOR, ret);
 419                 return ret;
 420         }
 421
 422         if (tmr_atboot && started == 0) {
 423                 printk(KERN_INFO PFX "Starting Watchdog Timer\n");
 424                 s3c2410wdt_start();
 425         } else if (!tmr_atboot) {
 426                 /* if we're not enabling the watchdog, then ensure it is
 427                  * disabled if it has been left running from the bootloader
 428                  * or other source */
 429
 430                 s3c2410wdt_stop();
 431         }
 432
 433         return 0;
 434 }
 435
 436 static int s3c2410wdt_remove(struct platform_device *dev)
 437 {
 438         if (wdt_mem != NULL) {
 439                 release_resource(wdt_mem);
 440                 kfree(wdt_mem);
 441                 wdt_mem = NULL;
 442         }
 443
 444         if (wdt_irq != NULL) {
 445                 free_irq(wdt_irq->start, dev);
 446                 wdt_irq = NULL;
 447         }
 448
 449         if (wdt_clock != NULL) {
 450                 clk_disable(wdt_clock);
 451                 clk_put(wdt_clock);
 452                 wdt_clock = NULL;
 453         }
 454
 455         misc_deregister(&s3c2410wdt_miscdev);
 456         return 0;
 457 }
 458
 459 static void s3c2410wdt_shutdown(struct platform_device *dev)
 460 {
 461         s3c2410wdt_stop();
 462 }
 463
 464 #ifdef CONFIG_PM
 465
 466 static unsigned long wtcon_save;
 467 static unsigned long wtdat_save;
 468
 469 static int s3c2410wdt_suspend(struct platform_device *dev, pm_message_t state)
 470 {
 471         /* Save watchdog state, and turn it off. */
 472         wtcon_save = readl(wdt_base + S3C2410_WTCON);
 473         wtdat_save = readl(wdt_base + S3C2410_WTDAT);
 474
 475         /* Note that WTCNT doesn't need to be saved. */
 476         s3c2410wdt_stop();
 477
 478         return 0;
 479 }
 480
 481 static int s3c2410wdt_resume(struct platform_device *dev)
 482 {
 483         /* Restore watchdog state. */
 484
 485         writel(wtdat_save, wdt_base + S3C2410_WTDAT);
 486         writel(wtdat_save, wdt_base + S3C2410_WTCNT); /* Reset count */
 487         writel(wtcon_save, wdt_base + S3C2410_WTCON);
 488
 489         printk(KERN_INFO PFX "watchdog %sabled\n",
 490                (wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
 491
 492         return 0;
 493 }
 494
 495 #else
 496 #define s3c2410wdt_suspend NULL
 497 #define s3c2410wdt_resume  NULL
 498 #endif /* CONFIG_PM */
 499
 500
 501 static struct platform_driver s3c2410wdt_driver = {
 502         .probe          = s3c2410wdt_probe,
 503         .remove         = s3c2410wdt_remove,
 504         .shutdown       = s3c2410wdt_shutdown,
 505         .suspend        = s3c2410wdt_suspend,
 506         .resume         = s3c2410wdt_resume,
 507         .driver         = {
 508                 .owner  = THIS_MODULE,
 509                 .name   = "s3c2410-wdt",
 510         },
 511 };
 512
 513
 514 static char banner[] __initdata = KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n";
 515
 516 static int __init watchdog_init(void)
 517 {
 518         printk(banner);
 519         return platform_driver_register(&s3c2410wdt_driver);
 520 }
 521
 522 static void __exit watchdog_exit(void)
 523 {
 524         platform_driver_unregister(&s3c2410wdt_driver);
 525 }
 526
 527 module_init(watchdog_init);
 528 module_exit(watchdog_exit);
 529
 530 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "
 531               "Dimitry Andric <dimitry.andric@tomtom.com>");
 532 MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
 533 MODULE_LICENSE("GPL");
 534 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);