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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 #include <linux/uaccess.h>
  50 #include <linux/io.h>
  51
  52 #include <mach/map.h>
  53
  54 #undef S3C_VA_WATCHDOG
  55 #define S3C_VA_WATCHDOG (0)
  56
  57 #include <asm/plat-s3c/regs-watchdog.h>
  58
  59 #define PFX "s3c2410-wdt: "
  60
  61 #define CONFIG_S3C2410_WATCHDOG_ATBOOT          (0)
  62 #define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME    (15)
  63
  64 static int nowayout     = WATCHDOG_NOWAYOUT;
  65 static int tmr_margin   = CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME;
  66 static int tmr_atboot   = CONFIG_S3C2410_WATCHDOG_ATBOOT;
  67 static int soft_noboot;
  68 static int debug;
  69
  70 module_param(tmr_margin,  int, 0);
  71 module_param(tmr_atboot,  int, 0);
  72 module_param(nowayout,    int, 0);
  73 module_param(soft_noboot, int, 0);
  74 module_param(debug,       int, 0);
  75
  76 MODULE_PARM_DESC(tmr_margin, "Watchdog tmr_margin in seconds. default="
  77                 __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME) ")");
  78 MODULE_PARM_DESC(tmr_atboot,
  79                 "Watchdog is started at boot time if set to 1, default="
  80                         __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_ATBOOT));
  81 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  82                         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  83 MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)");
  84 MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug, (default 0)");
  85
  86
  87 typedef enum close_state {
  88         CLOSE_STATE_NOT,
  89         CLOSE_STATE_ALLOW = 0x4021
  90 } close_state_t;
  91
  92 static unsigned long open_lock;
  93 static struct device    *wdt_dev;       /* platform device attached to */
  94 static struct resource  *wdt_mem;
  95 static struct resource  *wdt_irq;
  96 static struct clk       *wdt_clock;
  97 static void __iomem     *wdt_base;
  98 static unsigned int      wdt_count;
  99 static close_state_t     allow_close;
 100 static DEFINE_SPINLOCK(wdt_lock);
 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 void s3c2410wdt_keepalive(void)
 112 {
 113         spin_lock(&wdt_lock);
 114         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 115         spin_unlock(&wdt_lock);
 116 }
 117
 118 static void __s3c2410wdt_stop(void)
 119 {
 120         unsigned long wtcon;
 121
 122         wtcon = readl(wdt_base + S3C2410_WTCON);
 123         wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
 124         writel(wtcon, wdt_base + S3C2410_WTCON);
 125 }
 126
 127 static void s3c2410wdt_stop(void)
 128 {
 129         spin_lock(&wdt_lock);
 130         __s3c2410wdt_stop();
 131         spin_unlock(&wdt_lock);
 132 }
 133
 134 static void s3c2410wdt_start(void)
 135 {
 136         unsigned long wtcon;
 137
 138         spin_lock(&wdt_lock);
 139
 140         __s3c2410wdt_stop();
 141
 142         wtcon = readl(wdt_base + S3C2410_WTCON);
 143         wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;
 144
 145         if (soft_noboot) {
 146                 wtcon |= S3C2410_WTCON_INTEN;
 147                 wtcon &= ~S3C2410_WTCON_RSTEN;
 148         } else {
 149                 wtcon &= ~S3C2410_WTCON_INTEN;
 150                 wtcon |= S3C2410_WTCON_RSTEN;
 151         }
 152
 153         DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
 154             __func__, wdt_count, wtcon);
 155
 156         writel(wdt_count, wdt_base + S3C2410_WTDAT);
 157         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 158         writel(wtcon, wdt_base + S3C2410_WTCON);
 159         spin_unlock(&wdt_lock);
 160 }
 161
 162 static int s3c2410wdt_set_heartbeat(int timeout)
 163 {
 164         unsigned int freq = clk_get_rate(wdt_clock);
 165         unsigned int count;
 166         unsigned int divisor = 1;
 167         unsigned long wtcon;
 168
 169         if (timeout < 1)
 170                 return -EINVAL;
 171
 172         freq /= 128;
 173         count = timeout * freq;
 174
 175         DBG("%s: count=%d, timeout=%d, freq=%d\n",
 176             __func__, count, timeout, freq);
 177
 178         /* if the count is bigger than the watchdog register,
 179            then work out what we need to do (and if) we can
 180            actually make this value
 181         */
 182
 183         if (count >= 0x10000) {
 184                 for (divisor = 1; divisor <= 0x100; divisor++) {
 185                         if ((count / divisor) < 0x10000)
 186                                 break;
 187                 }
 188
 189                 if ((count / divisor) >= 0x10000) {
 190                         dev_err(wdt_dev, "timeout %d too big\n", timeout);
 191                         return -EINVAL;
 192                 }
 193         }
 194
 195         tmr_margin = timeout;
 196
 197         DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
 198             __func__, timeout, divisor, count, count/divisor);
 199
 200         count /= divisor;
 201         wdt_count = count;
 202
 203         /* update the pre-scaler */
 204         wtcon = readl(wdt_base + S3C2410_WTCON);
 205         wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
 206         wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);
 207
 208         writel(count, wdt_base + S3C2410_WTDAT);
 209         writel(wtcon, wdt_base + S3C2410_WTCON);
 210
 211         return 0;
 212 }
 213
 214 /*
 215  *      /dev/watchdog handling
 216  */
 217
 218 static int s3c2410wdt_open(struct inode *inode, struct file *file)
 219 {
 220         if (test_and_set_bit(0, &open_lock))
 221                 return -EBUSY;
 222
 223         if (nowayout)
 224                 __module_get(THIS_MODULE);
 225
 226         allow_close = CLOSE_STATE_NOT;
 227
 228         /* start the timer */
 229         s3c2410wdt_start();
 230         return nonseekable_open(inode, file);
 231 }
 232
 233 static int s3c2410wdt_release(struct inode *inode, struct file *file)
 234 {
 235         /*
 236          *      Shut off the timer.
 237          *      Lock it in if it's a module and we set nowayout
 238          */
 239
 240         if (allow_close == CLOSE_STATE_ALLOW)
 241                 s3c2410wdt_stop();
 242         else {
 243                 dev_err(wdt_dev, "Unexpected close, not stopping watchdog\n");
 244                 s3c2410wdt_keepalive();
 245         }
 246         allow_close = CLOSE_STATE_NOT;
 247         clear_bit(0, &open_lock);
 248         return 0;
 249 }
 250
 251 static ssize_t s3c2410wdt_write(struct file *file, const char __user *data,
 252                                 size_t len, loff_t *ppos)
 253 {
 254         /*
 255          *      Refresh the timer.
 256          */
 257         if (len) {
 258                 if (!nowayout) {
 259                         size_t i;
 260
 261                         /* In case it was set long ago */
 262                         allow_close = CLOSE_STATE_NOT;
 263
 264                         for (i = 0; i != len; i++) {
 265                                 char c;
 266
 267                                 if (get_user(c, data + i))
 268                                         return -EFAULT;
 269                                 if (c == 'V')
 270                                         allow_close = CLOSE_STATE_ALLOW;
 271                         }
 272                 }
 273                 s3c2410wdt_keepalive();
 274         }
 275         return len;
 276 }
 277
 278 #define OPTIONS WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE
 279
 280 static const struct watchdog_info s3c2410_wdt_ident = {
 281         .options          =     OPTIONS,
 282         .firmware_version =     0,
 283         .identity         =     "S3C2410 Watchdog",
 284 };
 285
 286
 287 static long s3c2410wdt_ioctl(struct file *file, unsigned int cmd,
 288                                                         unsigned long arg)
 289 {
 290         void __user *argp = (void __user *)arg;
 291         int __user *p = argp;
 292         int new_margin;
 293
 294         switch (cmd) {
 295         case WDIOC_GETSUPPORT:
 296                 return copy_to_user(argp, &s3c2410_wdt_ident,
 297                         sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0;
 298         case WDIOC_GETSTATUS:
 299         case WDIOC_GETBOOTSTATUS:
 300                 return put_user(0, p);
 301         case WDIOC_KEEPALIVE:
 302                 s3c2410wdt_keepalive();
 303                 return 0;
 304         case WDIOC_SETTIMEOUT:
 305                 if (get_user(new_margin, p))
 306                         return -EFAULT;
 307                 if (s3c2410wdt_set_heartbeat(new_margin))
 308                         return -EINVAL;
 309                 s3c2410wdt_keepalive();
 310                 return put_user(tmr_margin, p);
 311         case WDIOC_GETTIMEOUT:
 312                 return put_user(tmr_margin, p);
 313         default:
 314                 return -ENOTTY;
 315         }
 316 }
 317
 318 /* kernel interface */
 319
 320 static const struct file_operations s3c2410wdt_fops = {
 321         .owner          = THIS_MODULE,
 322         .llseek         = no_llseek,
 323         .write          = s3c2410wdt_write,
 324         .unlocked_ioctl = s3c2410wdt_ioctl,
 325         .open           = s3c2410wdt_open,
 326         .release        = s3c2410wdt_release,
 327 };
 328
 329 static struct miscdevice s3c2410wdt_miscdev = {
 330         .minor          = WATCHDOG_MINOR,
 331         .name           = "watchdog",
 332         .fops           = &s3c2410wdt_fops,
 333 };
 334
 335 /* interrupt handler code */
 336
 337 static irqreturn_t s3c2410wdt_irq(int irqno, void *param)
 338 {
 339         dev_info(wdt_dev, "watchdog timer expired (irq)\n");
 340
 341         s3c2410wdt_keepalive();
 342         return IRQ_HANDLED;
 343 }
 344 /* device interface */
 345
 346 static int s3c2410wdt_probe(struct platform_device *pdev)
 347 {
 348         struct resource *res;
 349         struct device *dev;
 350         unsigned int wtcon;
 351         int started = 0;
 352         int ret;
 353         int size;
 354
 355         DBG("%s: probe=%p\n", __func__, pdev);
 356
 357         dev = &pdev->dev;
 358         wdt_dev = &pdev->dev;
 359
 360         /* get the memory region for the watchdog timer */
 361
 362         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 363         if (res == NULL) {
 364                 dev_err(dev, "no memory resource specified\n");
 365                 return -ENOENT;
 366         }
 367
 368         size = (res->end-res->start)+1;
 369         wdt_mem = request_mem_region(res->start, size, pdev->name);
 370         if (wdt_mem == NULL) {
 371                 dev_err(dev, "failed to get memory region\n");
 372                 ret = -ENOENT;
 373                 goto err_req;
 374         }
 375
 376         wdt_base = ioremap(res->start, size);
 377         if (wdt_base == 0) {
 378                 dev_err(dev, "failed to ioremap() region\n");
 379                 ret = -EINVAL;
 380                 goto err_req;
 381         }
 382
 383         DBG("probe: mapped wdt_base=%p\n", wdt_base);
 384
 385         wdt_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 386         if (wdt_irq == NULL) {
 387                 dev_err(dev, "no irq resource specified\n");
 388                 ret = -ENOENT;
 389                 goto err_map;
 390         }
 391
 392         ret = request_irq(wdt_irq->start, s3c2410wdt_irq, 0, pdev->name, pdev);
 393         if (ret != 0) {
 394                 dev_err(dev, "failed to install irq (%d)\n", ret);
 395                 goto err_map;
 396         }
 397
 398         wdt_clock = clk_get(&pdev->dev, "watchdog");
 399         if (IS_ERR(wdt_clock)) {
 400                 dev_err(dev, "failed to find watchdog clock source\n");
 401                 ret = PTR_ERR(wdt_clock);
 402                 goto err_irq;
 403         }
 404
 405         clk_enable(wdt_clock);
 406
 407         /* see if we can actually set the requested timer margin, and if
 408          * not, try the default value */
 409
 410         if (s3c2410wdt_set_heartbeat(tmr_margin)) {
 411                 started = s3c2410wdt_set_heartbeat(
 412                                         CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 413
 414                 if (started == 0)
 415                         dev_info(dev,
 416                            "tmr_margin value out of range, default %d used\n",
 417                                CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 418                 else
 419                         dev_info(dev, "default timer value is out of range, cannot start\n");
 420         }
 421
 422         ret = misc_register(&s3c2410wdt_miscdev);
 423         if (ret) {
 424                 dev_err(dev, "cannot register miscdev on minor=%d (%d)\n",
 425                         WATCHDOG_MINOR, ret);
 426                 goto err_clk;
 427         }
 428
 429         if (tmr_atboot && started == 0) {
 430                 dev_info(dev, "starting watchdog timer\n");
 431                 s3c2410wdt_start();
 432         } else if (!tmr_atboot) {
 433                 /* if we're not enabling the watchdog, then ensure it is
 434                  * disabled if it has been left running from the bootloader
 435                  * or other source */
 436
 437                 s3c2410wdt_stop();
 438         }
 439
 440         /* print out a statement of readiness */
 441
 442         wtcon = readl(wdt_base + S3C2410_WTCON);
 443
 444         dev_info(dev, "watchdog %sactive, reset %sabled, irq %sabled\n",
 445                  (wtcon & S3C2410_WTCON_ENABLE) ?  "" : "in",
 446                  (wtcon & S3C2410_WTCON_RSTEN) ? "" : "dis",
 447                  (wtcon & S3C2410_WTCON_INTEN) ? "" : "en");
 448
 449         return 0;
 450
 451  err_clk:
 452         clk_disable(wdt_clock);
 453         clk_put(wdt_clock);
 454
 455  err_irq:
 456         free_irq(wdt_irq->start, pdev);
 457
 458  err_map:
 459         iounmap(wdt_base);
 460
 461  err_req:
 462         release_resource(wdt_mem);
 463         kfree(wdt_mem);
 464
 465         return ret;
 466 }
 467
 468 static int s3c2410wdt_remove(struct platform_device *dev)
 469 {
 470         release_resource(wdt_mem);
 471         kfree(wdt_mem);
 472         wdt_mem = NULL;
 473
 474         free_irq(wdt_irq->start, dev);
 475         wdt_irq = NULL;
 476
 477         clk_disable(wdt_clock);
 478         clk_put(wdt_clock);
 479         wdt_clock = NULL;
 480
 481         iounmap(wdt_base);
 482         misc_deregister(&s3c2410wdt_miscdev);
 483         return 0;
 484 }
 485
 486 static void s3c2410wdt_shutdown(struct platform_device *dev)
 487 {
 488         s3c2410wdt_stop();
 489 }
 490
 491 #ifdef CONFIG_PM
 492
 493 static unsigned long wtcon_save;
 494 static unsigned long wtdat_save;
 495
 496 static int s3c2410wdt_suspend(struct platform_device *dev, pm_message_t state)
 497 {
 498         /* Save watchdog state, and turn it off. */
 499         wtcon_save = readl(wdt_base + S3C2410_WTCON);
 500         wtdat_save = readl(wdt_base + S3C2410_WTDAT);
 501
 502         /* Note that WTCNT doesn't need to be saved. */
 503         s3c2410wdt_stop();
 504
 505         return 0;
 506 }
 507
 508 static int s3c2410wdt_resume(struct platform_device *dev)
 509 {
 510         /* Restore watchdog state. */
 511
 512         writel(wtdat_save, wdt_base + S3C2410_WTDAT);
 513         writel(wtdat_save, wdt_base + S3C2410_WTCNT); /* Reset count */
 514         writel(wtcon_save, wdt_base + S3C2410_WTCON);
 515
 516         printk(KERN_INFO PFX "watchdog %sabled\n",
 517                (wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
 518
 519         return 0;
 520 }
 521
 522 #else
 523 #define s3c2410wdt_suspend NULL
 524 #define s3c2410wdt_resume  NULL
 525 #endif /* CONFIG_PM */
 526
 527
 528 static struct platform_driver s3c2410wdt_driver = {
 529         .probe          = s3c2410wdt_probe,
 530         .remove         = s3c2410wdt_remove,
 531         .shutdown       = s3c2410wdt_shutdown,
 532         .suspend        = s3c2410wdt_suspend,
 533         .resume         = s3c2410wdt_resume,
 534         .driver         = {
 535                 .owner  = THIS_MODULE,
 536                 .name   = "s3c2410-wdt",
 537         },
 538 };
 539
 540
 541 static char banner[] __initdata =
 542         KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n";
 543
 544 static int __init watchdog_init(void)
 545 {
 546         printk(banner);
 547         return platform_driver_register(&s3c2410wdt_driver);
 548 }
 549
 550 static void __exit watchdog_exit(void)
 551 {
 552         platform_driver_unregister(&s3c2410wdt_driver);
 553 }
 554
 555 module_init(watchdog_init);
 556 module_exit(watchdog_exit);
 557
 558 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "
 559               "Dimitry Andric <dimitry.andric@tomtom.com>");
 560 MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
 561 MODULE_LICENSE("GPL");
 562 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 563 MODULE_ALIAS("platform:s3c2410-wdt");