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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@lxorguk.ukuu.org.uk>
  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
  26 #include <linux/module.h>
  27 #include <linux/moduleparam.h>
  28 #include <linux/types.h>
  29 #include <linux/timer.h>
  30 #include <linux/miscdevice.h>
  31 #include <linux/watchdog.h>
  32 #include <linux/fs.h>
  33 #include <linux/init.h>
  34 #include <linux/platform_device.h>
  35 #include <linux/interrupt.h>
  36 #include <linux/clk.h>
  37 #include <linux/uaccess.h>
  38 #include <linux/io.h>
  39
  40 #include <mach/map.h>
  41
  42 #undef S3C_VA_WATCHDOG
  43 #define S3C_VA_WATCHDOG (0)
  44
  45 #include <plat/regs-watchdog.h>
  46
  47 #define PFX "s3c2410-wdt: "
  48
  49 #define CONFIG_S3C2410_WATCHDOG_ATBOOT          (0)
  50 #define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME    (15)
  51
  52 static int nowayout     = WATCHDOG_NOWAYOUT;
  53 static int tmr_margin   = CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME;
  54 static int tmr_atboot   = CONFIG_S3C2410_WATCHDOG_ATBOOT;
  55 static int soft_noboot;
  56 static int debug;
  57
  58 module_param(tmr_margin,  int, 0);
  59 module_param(tmr_atboot,  int, 0);
  60 module_param(nowayout,    int, 0);
  61 module_param(soft_noboot, int, 0);
  62 module_param(debug,       int, 0);
  63
  64 MODULE_PARM_DESC(tmr_margin, "Watchdog tmr_margin in seconds. default="
  65                 __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME) ")");
  66 MODULE_PARM_DESC(tmr_atboot,
  67                 "Watchdog is started at boot time if set to 1, default="
  68                         __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_ATBOOT));
  69 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  70                         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  71 MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, "
  72                         "0 to reboot (default depends on ONLY_TESTING)");
  73 MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug, (default 0)");
  74
  75 static unsigned long open_lock;
  76 static struct device    *wdt_dev;       /* platform device attached to */
  77 static struct resource  *wdt_mem;
  78 static struct resource  *wdt_irq;
  79 static struct clk       *wdt_clock;
  80 static void __iomem     *wdt_base;
  81 static unsigned int      wdt_count;
  82 static char              expect_close;
  83 static DEFINE_SPINLOCK(wdt_lock);
  84
  85 /* watchdog control routines */
  86
  87 #define DBG(msg...) do { \
  88         if (debug) \
  89                 printk(KERN_INFO msg); \
  90         } while (0)
  91
  92 /* functions */
  93
  94 static void s3c2410wdt_keepalive(void)
  95 {
  96         spin_lock(&wdt_lock);
  97         writel(wdt_count, wdt_base + S3C2410_WTCNT);
  98         spin_unlock(&wdt_lock);
  99 }
 100
 101 static void __s3c2410wdt_stop(void)
 102 {
 103         unsigned long wtcon;
 104
 105         wtcon = readl(wdt_base + S3C2410_WTCON);
 106         wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
 107         writel(wtcon, wdt_base + S3C2410_WTCON);
 108 }
 109
 110 static void s3c2410wdt_stop(void)
 111 {
 112         spin_lock(&wdt_lock);
 113         __s3c2410wdt_stop();
 114         spin_unlock(&wdt_lock);
 115 }
 116
 117 static void s3c2410wdt_start(void)
 118 {
 119         unsigned long wtcon;
 120
 121         spin_lock(&wdt_lock);
 122
 123         __s3c2410wdt_stop();
 124
 125         wtcon = readl(wdt_base + S3C2410_WTCON);
 126         wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;
 127
 128         if (soft_noboot) {
 129                 wtcon |= S3C2410_WTCON_INTEN;
 130                 wtcon &= ~S3C2410_WTCON_RSTEN;
 131         } else {
 132                 wtcon &= ~S3C2410_WTCON_INTEN;
 133                 wtcon |= S3C2410_WTCON_RSTEN;
 134         }
 135
 136         DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
 137             __func__, wdt_count, wtcon);
 138
 139         writel(wdt_count, wdt_base + S3C2410_WTDAT);
 140         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 141         writel(wtcon, wdt_base + S3C2410_WTCON);
 142         spin_unlock(&wdt_lock);
 143 }
 144
 145 static int s3c2410wdt_set_heartbeat(int timeout)
 146 {
 147         unsigned int freq = clk_get_rate(wdt_clock);
 148         unsigned int count;
 149         unsigned int divisor = 1;
 150         unsigned long wtcon;
 151
 152         if (timeout < 1)
 153                 return -EINVAL;
 154
 155         freq /= 128;
 156         count = timeout * freq;
 157
 158         DBG("%s: count=%d, timeout=%d, freq=%d\n",
 159             __func__, count, timeout, freq);
 160
 161         /* if the count is bigger than the watchdog register,
 162            then work out what we need to do (and if) we can
 163            actually make this value
 164         */
 165
 166         if (count >= 0x10000) {
 167                 for (divisor = 1; divisor <= 0x100; divisor++) {
 168                         if ((count / divisor) < 0x10000)
 169                                 break;
 170                 }
 171
 172                 if ((count / divisor) >= 0x10000) {
 173                         dev_err(wdt_dev, "timeout %d too big\n", timeout);
 174                         return -EINVAL;
 175                 }
 176         }
 177
 178         tmr_margin = timeout;
 179
 180         DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
 181             __func__, timeout, divisor, count, count/divisor);
 182
 183         count /= divisor;
 184         wdt_count = count;
 185
 186         /* update the pre-scaler */
 187         wtcon = readl(wdt_base + S3C2410_WTCON);
 188         wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
 189         wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);
 190
 191         writel(count, wdt_base + S3C2410_WTDAT);
 192         writel(wtcon, wdt_base + S3C2410_WTCON);
 193
 194         return 0;
 195 }
 196
 197 /*
 198  *      /dev/watchdog handling
 199  */
 200
 201 static int s3c2410wdt_open(struct inode *inode, struct file *file)
 202 {
 203         if (test_and_set_bit(0, &open_lock))
 204                 return -EBUSY;
 205
 206         if (nowayout)
 207                 __module_get(THIS_MODULE);
 208
 209         expect_close = 0;
 210
 211         /* start the timer */
 212         s3c2410wdt_start();
 213         return nonseekable_open(inode, file);
 214 }
 215
 216 static int s3c2410wdt_release(struct inode *inode, struct file *file)
 217 {
 218         /*
 219          *      Shut off the timer.
 220          *      Lock it in if it's a module and we set nowayout
 221          */
 222
 223         if (expect_close == 42)
 224                 s3c2410wdt_stop();
 225         else {
 226                 dev_err(wdt_dev, "Unexpected close, not stopping watchdog\n");
 227                 s3c2410wdt_keepalive();
 228         }
 229         expect_close = 0;
 230         clear_bit(0, &open_lock);
 231         return 0;
 232 }
 233
 234 static ssize_t s3c2410wdt_write(struct file *file, const char __user *data,
 235                                 size_t len, loff_t *ppos)
 236 {
 237         /*
 238          *      Refresh the timer.
 239          */
 240         if (len) {
 241                 if (!nowayout) {
 242                         size_t i;
 243
 244                         /* In case it was set long ago */
 245                         expect_close = 0;
 246
 247                         for (i = 0; i != len; i++) {
 248                                 char c;
 249
 250                                 if (get_user(c, data + i))
 251                                         return -EFAULT;
 252                                 if (c == 'V')
 253                                         expect_close = 42;
 254                         }
 255                 }
 256                 s3c2410wdt_keepalive();
 257         }
 258         return len;
 259 }
 260
 261 #define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
 262
 263 static const struct watchdog_info s3c2410_wdt_ident = {
 264         .options          =     OPTIONS,
 265         .firmware_version =     0,
 266         .identity         =     "S3C2410 Watchdog",
 267 };
 268
 269
 270 static long s3c2410wdt_ioctl(struct file *file, unsigned int cmd,
 271                                                         unsigned long arg)
 272 {
 273         void __user *argp = (void __user *)arg;
 274         int __user *p = argp;
 275         int new_margin;
 276
 277         switch (cmd) {
 278         case WDIOC_GETSUPPORT:
 279                 return copy_to_user(argp, &s3c2410_wdt_ident,
 280                         sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0;
 281         case WDIOC_GETSTATUS:
 282         case WDIOC_GETBOOTSTATUS:
 283                 return put_user(0, p);
 284         case WDIOC_KEEPALIVE:
 285                 s3c2410wdt_keepalive();
 286                 return 0;
 287         case WDIOC_SETTIMEOUT:
 288                 if (get_user(new_margin, p))
 289                         return -EFAULT;
 290                 if (s3c2410wdt_set_heartbeat(new_margin))
 291                         return -EINVAL;
 292                 s3c2410wdt_keepalive();
 293                 return put_user(tmr_margin, p);
 294         case WDIOC_GETTIMEOUT:
 295                 return put_user(tmr_margin, p);
 296         default:
 297                 return -ENOTTY;
 298         }
 299 }
 300
 301 /* kernel interface */
 302
 303 static const struct file_operations s3c2410wdt_fops = {
 304         .owner          = THIS_MODULE,
 305         .llseek         = no_llseek,
 306         .write          = s3c2410wdt_write,
 307         .unlocked_ioctl = s3c2410wdt_ioctl,
 308         .open           = s3c2410wdt_open,
 309         .release        = s3c2410wdt_release,
 310 };
 311
 312 static struct miscdevice s3c2410wdt_miscdev = {
 313         .minor          = WATCHDOG_MINOR,
 314         .name           = "watchdog",
 315         .fops           = &s3c2410wdt_fops,
 316 };
 317
 318 /* interrupt handler code */
 319
 320 static irqreturn_t s3c2410wdt_irq(int irqno, void *param)
 321 {
 322         dev_info(wdt_dev, "watchdog timer expired (irq)\n");
 323
 324         s3c2410wdt_keepalive();
 325         return IRQ_HANDLED;
 326 }
 327 /* device interface */
 328
 329 static int __devinit s3c2410wdt_probe(struct platform_device *pdev)
 330 {
 331         struct resource *res;
 332         struct device *dev;
 333         unsigned int wtcon;
 334         int started = 0;
 335         int ret;
 336         int size;
 337
 338         DBG("%s: probe=%p\n", __func__, pdev);
 339
 340         dev = &pdev->dev;
 341         wdt_dev = &pdev->dev;
 342
 343         /* get the memory region for the watchdog timer */
 344
 345         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 346         if (res == NULL) {
 347                 dev_err(dev, "no memory resource specified\n");
 348                 return -ENOENT;
 349         }
 350
 351         size = (res->end - res->start) + 1;
 352         wdt_mem = request_mem_region(res->start, size, pdev->name);
 353         if (wdt_mem == NULL) {
 354                 dev_err(dev, "failed to get memory region\n");
 355                 ret = -ENOENT;
 356                 goto err_req;
 357         }
 358
 359         wdt_base = ioremap(res->start, size);
 360         if (wdt_base == NULL) {
 361                 dev_err(dev, "failed to ioremap() region\n");
 362                 ret = -EINVAL;
 363                 goto err_req;
 364         }
 365
 366         DBG("probe: mapped wdt_base=%p\n", wdt_base);
 367
 368         wdt_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 369         if (wdt_irq == NULL) {
 370                 dev_err(dev, "no irq resource specified\n");
 371                 ret = -ENOENT;
 372                 goto err_map;
 373         }
 374
 375         ret = request_irq(wdt_irq->start, s3c2410wdt_irq, 0, pdev->name, pdev);
 376         if (ret != 0) {
 377                 dev_err(dev, "failed to install irq (%d)\n", ret);
 378                 goto err_map;
 379         }
 380
 381         wdt_clock = clk_get(&pdev->dev, "watchdog");
 382         if (IS_ERR(wdt_clock)) {
 383                 dev_err(dev, "failed to find watchdog clock source\n");
 384                 ret = PTR_ERR(wdt_clock);
 385                 goto err_irq;
 386         }
 387
 388         clk_enable(wdt_clock);
 389
 390         /* see if we can actually set the requested timer margin, and if
 391          * not, try the default value */
 392
 393         if (s3c2410wdt_set_heartbeat(tmr_margin)) {
 394                 started = s3c2410wdt_set_heartbeat(
 395                                         CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 396
 397                 if (started == 0)
 398                         dev_info(dev,
 399                            "tmr_margin value out of range, default %d used\n",
 400                                CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 401                 else
 402                         dev_info(dev, "default timer value is out of range, "
 403                                                         "cannot start\n");
 404         }
 405
 406         ret = misc_register(&s3c2410wdt_miscdev);
 407         if (ret) {
 408                 dev_err(dev, "cannot register miscdev on minor=%d (%d)\n",
 409                         WATCHDOG_MINOR, ret);
 410                 goto err_clk;
 411         }
 412
 413         if (tmr_atboot && started == 0) {
 414                 dev_info(dev, "starting watchdog timer\n");
 415                 s3c2410wdt_start();
 416         } else if (!tmr_atboot) {
 417                 /* if we're not enabling the watchdog, then ensure it is
 418                  * disabled if it has been left running from the bootloader
 419                  * or other source */
 420
 421                 s3c2410wdt_stop();
 422         }
 423
 424         /* print out a statement of readiness */
 425
 426         wtcon = readl(wdt_base + S3C2410_WTCON);
 427
 428         dev_info(dev, "watchdog %sactive, reset %sabled, irq %sabled\n",
 429                  (wtcon & S3C2410_WTCON_ENABLE) ?  "" : "in",
 430                  (wtcon & S3C2410_WTCON_RSTEN) ? "" : "dis",
 431                  (wtcon & S3C2410_WTCON_INTEN) ? "" : "en");
 432
 433         return 0;
 434
 435  err_clk:
 436         clk_disable(wdt_clock);
 437         clk_put(wdt_clock);
 438
 439  err_irq:
 440         free_irq(wdt_irq->start, pdev);
 441
 442  err_map:
 443         iounmap(wdt_base);
 444
 445  err_req:
 446         release_resource(wdt_mem);
 447         kfree(wdt_mem);
 448
 449         return ret;
 450 }
 451
 452 static int __devexit s3c2410wdt_remove(struct platform_device *dev)
 453 {
 454         release_resource(wdt_mem);
 455         kfree(wdt_mem);
 456         wdt_mem = NULL;
 457
 458         free_irq(wdt_irq->start, dev);
 459         wdt_irq = NULL;
 460
 461         clk_disable(wdt_clock);
 462         clk_put(wdt_clock);
 463         wdt_clock = NULL;
 464
 465         iounmap(wdt_base);
 466         misc_deregister(&s3c2410wdt_miscdev);
 467         return 0;
 468 }
 469
 470 static void s3c2410wdt_shutdown(struct platform_device *dev)
 471 {
 472         s3c2410wdt_stop();
 473 }
 474
 475 #ifdef CONFIG_PM
 476
 477 static unsigned long wtcon_save;
 478 static unsigned long wtdat_save;
 479
 480 static int s3c2410wdt_suspend(struct platform_device *dev, pm_message_t state)
 481 {
 482         /* Save watchdog state, and turn it off. */
 483         wtcon_save = readl(wdt_base + S3C2410_WTCON);
 484         wtdat_save = readl(wdt_base + S3C2410_WTDAT);
 485
 486         /* Note that WTCNT doesn't need to be saved. */
 487         s3c2410wdt_stop();
 488
 489         return 0;
 490 }
 491
 492 static int s3c2410wdt_resume(struct platform_device *dev)
 493 {
 494         /* Restore watchdog state. */
 495
 496         writel(wtdat_save, wdt_base + S3C2410_WTDAT);
 497         writel(wtdat_save, wdt_base + S3C2410_WTCNT); /* Reset count */
 498         writel(wtcon_save, wdt_base + S3C2410_WTCON);
 499
 500         printk(KERN_INFO PFX "watchdog %sabled\n",
 501                (wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
 502
 503         return 0;
 504 }
 505
 506 #else
 507 #define s3c2410wdt_suspend NULL
 508 #define s3c2410wdt_resume  NULL
 509 #endif /* CONFIG_PM */
 510
 511
 512 static struct platform_driver s3c2410wdt_driver = {
 513         .probe          = s3c2410wdt_probe,
 514         .remove         = __devexit_p(s3c2410wdt_remove),
 515         .shutdown       = s3c2410wdt_shutdown,
 516         .suspend        = s3c2410wdt_suspend,
 517         .resume         = s3c2410wdt_resume,
 518         .driver         = {
 519                 .owner  = THIS_MODULE,
 520                 .name   = "s3c2410-wdt",
 521         },
 522 };
 523
 524
 525 static char banner[] __initdata =
 526         KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n";
 527
 528 static int __init watchdog_init(void)
 529 {
 530         printk(banner);
 531         return platform_driver_register(&s3c2410wdt_driver);
 532 }
 533
 534 static void __exit watchdog_exit(void)
 535 {
 536         platform_driver_unregister(&s3c2410wdt_driver);
 537 }
 538
 539 module_init(watchdog_init);
 540 module_exit(watchdog_exit);
 541
 542 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "
 543               "Dimitry Andric <dimitry.andric@tomtom.com>");
 544 MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
 545 MODULE_LICENSE("GPL");
 546 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 547 MODULE_ALIAS("platform:s3c2410-wdt");