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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 <asm/plat-s3c/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, 0 to reboot (default depends on ONLY_TESTING)");
  72 MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug, (default 0)");
  73
  74
  75 typedef enum close_state {
  76         CLOSE_STATE_NOT,
  77         CLOSE_STATE_ALLOW = 0x4021
  78 } close_state_t;
  79
  80 static unsigned long open_lock;
  81 static struct device    *wdt_dev;       /* platform device attached to */
  82 static struct resource  *wdt_mem;
  83 static struct resource  *wdt_irq;
  84 static struct clk       *wdt_clock;
  85 static void __iomem     *wdt_base;
  86 static unsigned int      wdt_count;
  87 static close_state_t     allow_close;
  88 static DEFINE_SPINLOCK(wdt_lock);
  89
  90 /* watchdog control routines */
  91
  92 #define DBG(msg...) do { \
  93         if (debug) \
  94                 printk(KERN_INFO msg); \
  95         } while (0)
  96
  97 /* functions */
  98
  99 static void s3c2410wdt_keepalive(void)
 100 {
 101         spin_lock(&wdt_lock);
 102         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 103         spin_unlock(&wdt_lock);
 104 }
 105
 106 static void __s3c2410wdt_stop(void)
 107 {
 108         unsigned long wtcon;
 109
 110         wtcon = readl(wdt_base + S3C2410_WTCON);
 111         wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
 112         writel(wtcon, wdt_base + S3C2410_WTCON);
 113 }
 114
 115 static void s3c2410wdt_stop(void)
 116 {
 117         spin_lock(&wdt_lock);
 118         __s3c2410wdt_stop();
 119         spin_unlock(&wdt_lock);
 120 }
 121
 122 static void s3c2410wdt_start(void)
 123 {
 124         unsigned long wtcon;
 125
 126         spin_lock(&wdt_lock);
 127
 128         __s3c2410wdt_stop();
 129
 130         wtcon = readl(wdt_base + S3C2410_WTCON);
 131         wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;
 132
 133         if (soft_noboot) {
 134                 wtcon |= S3C2410_WTCON_INTEN;
 135                 wtcon &= ~S3C2410_WTCON_RSTEN;
 136         } else {
 137                 wtcon &= ~S3C2410_WTCON_INTEN;
 138                 wtcon |= S3C2410_WTCON_RSTEN;
 139         }
 140
 141         DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
 142             __func__, wdt_count, wtcon);
 143
 144         writel(wdt_count, wdt_base + S3C2410_WTDAT);
 145         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 146         writel(wtcon, wdt_base + S3C2410_WTCON);
 147         spin_unlock(&wdt_lock);
 148 }
 149
 150 static int s3c2410wdt_set_heartbeat(int timeout)
 151 {
 152         unsigned int freq = clk_get_rate(wdt_clock);
 153         unsigned int count;
 154         unsigned int divisor = 1;
 155         unsigned long wtcon;
 156
 157         if (timeout < 1)
 158                 return -EINVAL;
 159
 160         freq /= 128;
 161         count = timeout * freq;
 162
 163         DBG("%s: count=%d, timeout=%d, freq=%d\n",
 164             __func__, count, timeout, freq);
 165
 166         /* if the count is bigger than the watchdog register,
 167            then work out what we need to do (and if) we can
 168            actually make this value
 169         */
 170
 171         if (count >= 0x10000) {
 172                 for (divisor = 1; divisor <= 0x100; divisor++) {
 173                         if ((count / divisor) < 0x10000)
 174                                 break;
 175                 }
 176
 177                 if ((count / divisor) >= 0x10000) {
 178                         dev_err(wdt_dev, "timeout %d too big\n", timeout);
 179                         return -EINVAL;
 180                 }
 181         }
 182
 183         tmr_margin = timeout;
 184
 185         DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
 186             __func__, timeout, divisor, count, count/divisor);
 187
 188         count /= divisor;
 189         wdt_count = count;
 190
 191         /* update the pre-scaler */
 192         wtcon = readl(wdt_base + S3C2410_WTCON);
 193         wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
 194         wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);
 195
 196         writel(count, wdt_base + S3C2410_WTDAT);
 197         writel(wtcon, wdt_base + S3C2410_WTCON);
 198
 199         return 0;
 200 }
 201
 202 /*
 203  *      /dev/watchdog handling
 204  */
 205
 206 static int s3c2410wdt_open(struct inode *inode, struct file *file)
 207 {
 208         if (test_and_set_bit(0, &open_lock))
 209                 return -EBUSY;
 210
 211         if (nowayout)
 212                 __module_get(THIS_MODULE);
 213
 214         allow_close = CLOSE_STATE_NOT;
 215
 216         /* start the timer */
 217         s3c2410wdt_start();
 218         return nonseekable_open(inode, file);
 219 }
 220
 221 static int s3c2410wdt_release(struct inode *inode, struct file *file)
 222 {
 223         /*
 224          *      Shut off the timer.
 225          *      Lock it in if it's a module and we set nowayout
 226          */
 227
 228         if (allow_close == CLOSE_STATE_ALLOW)
 229                 s3c2410wdt_stop();
 230         else {
 231                 dev_err(wdt_dev, "Unexpected close, not stopping watchdog\n");
 232                 s3c2410wdt_keepalive();
 233         }
 234         allow_close = CLOSE_STATE_NOT;
 235         clear_bit(0, &open_lock);
 236         return 0;
 237 }
 238
 239 static ssize_t s3c2410wdt_write(struct file *file, const char __user *data,
 240                                 size_t len, loff_t *ppos)
 241 {
 242         /*
 243          *      Refresh the timer.
 244          */
 245         if (len) {
 246                 if (!nowayout) {
 247                         size_t i;
 248
 249                         /* In case it was set long ago */
 250                         allow_close = CLOSE_STATE_NOT;
 251
 252                         for (i = 0; i != len; i++) {
 253                                 char c;
 254
 255                                 if (get_user(c, data + i))
 256                                         return -EFAULT;
 257                                 if (c == 'V')
 258                                         allow_close = CLOSE_STATE_ALLOW;
 259                         }
 260                 }
 261                 s3c2410wdt_keepalive();
 262         }
 263         return len;
 264 }
 265
 266 #define OPTIONS WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE
 267
 268 static const struct watchdog_info s3c2410_wdt_ident = {
 269         .options          =     OPTIONS,
 270         .firmware_version =     0,
 271         .identity         =     "S3C2410 Watchdog",
 272 };
 273
 274
 275 static long s3c2410wdt_ioctl(struct file *file, unsigned int cmd,
 276                                                         unsigned long arg)
 277 {
 278         void __user *argp = (void __user *)arg;
 279         int __user *p = argp;
 280         int new_margin;
 281
 282         switch (cmd) {
 283         case WDIOC_GETSUPPORT:
 284                 return copy_to_user(argp, &s3c2410_wdt_ident,
 285                         sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0;
 286         case WDIOC_GETSTATUS:
 287         case WDIOC_GETBOOTSTATUS:
 288                 return put_user(0, p);
 289         case WDIOC_KEEPALIVE:
 290                 s3c2410wdt_keepalive();
 291                 return 0;
 292         case WDIOC_SETTIMEOUT:
 293                 if (get_user(new_margin, p))
 294                         return -EFAULT;
 295                 if (s3c2410wdt_set_heartbeat(new_margin))
 296                         return -EINVAL;
 297                 s3c2410wdt_keepalive();
 298                 return put_user(tmr_margin, p);
 299         case WDIOC_GETTIMEOUT:
 300                 return put_user(tmr_margin, p);
 301         default:
 302                 return -ENOTTY;
 303         }
 304 }
 305
 306 /* kernel interface */
 307
 308 static const struct file_operations s3c2410wdt_fops = {
 309         .owner          = THIS_MODULE,
 310         .llseek         = no_llseek,
 311         .write          = s3c2410wdt_write,
 312         .unlocked_ioctl = s3c2410wdt_ioctl,
 313         .open           = s3c2410wdt_open,
 314         .release        = s3c2410wdt_release,
 315 };
 316
 317 static struct miscdevice s3c2410wdt_miscdev = {
 318         .minor          = WATCHDOG_MINOR,
 319         .name           = "watchdog",
 320         .fops           = &s3c2410wdt_fops,
 321 };
 322
 323 /* interrupt handler code */
 324
 325 static irqreturn_t s3c2410wdt_irq(int irqno, void *param)
 326 {
 327         dev_info(wdt_dev, "watchdog timer expired (irq)\n");
 328
 329         s3c2410wdt_keepalive();
 330         return IRQ_HANDLED;
 331 }
 332 /* device interface */
 333
 334 static int s3c2410wdt_probe(struct platform_device *pdev)
 335 {
 336         struct resource *res;
 337         struct device *dev;
 338         unsigned int wtcon;
 339         int started = 0;
 340         int ret;
 341         int size;
 342
 343         DBG("%s: probe=%p\n", __func__, pdev);
 344
 345         dev = &pdev->dev;
 346         wdt_dev = &pdev->dev;
 347
 348         /* get the memory region for the watchdog timer */
 349
 350         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 351         if (res == NULL) {
 352                 dev_err(dev, "no memory resource specified\n");
 353                 return -ENOENT;
 354         }
 355
 356         size = (res->end - res->start) + 1;
 357         wdt_mem = request_mem_region(res->start, size, pdev->name);
 358         if (wdt_mem == NULL) {
 359                 dev_err(dev, "failed to get memory region\n");
 360                 ret = -ENOENT;
 361                 goto err_req;
 362         }
 363
 364         wdt_base = ioremap(res->start, size);
 365         if (wdt_base == NULL) {
 366                 dev_err(dev, "failed to ioremap() region\n");
 367                 ret = -EINVAL;
 368                 goto err_req;
 369         }
 370
 371         DBG("probe: mapped wdt_base=%p\n", wdt_base);
 372
 373         wdt_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 374         if (wdt_irq == NULL) {
 375                 dev_err(dev, "no irq resource specified\n");
 376                 ret = -ENOENT;
 377                 goto err_map;
 378         }
 379
 380         ret = request_irq(wdt_irq->start, s3c2410wdt_irq, 0, pdev->name, pdev);
 381         if (ret != 0) {
 382                 dev_err(dev, "failed to install irq (%d)\n", ret);
 383                 goto err_map;
 384         }
 385
 386         wdt_clock = clk_get(&pdev->dev, "watchdog");
 387         if (IS_ERR(wdt_clock)) {
 388                 dev_err(dev, "failed to find watchdog clock source\n");
 389                 ret = PTR_ERR(wdt_clock);
 390                 goto err_irq;
 391         }
 392
 393         clk_enable(wdt_clock);
 394
 395         /* see if we can actually set the requested timer margin, and if
 396          * not, try the default value */
 397
 398         if (s3c2410wdt_set_heartbeat(tmr_margin)) {
 399                 started = s3c2410wdt_set_heartbeat(
 400                                         CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 401
 402                 if (started == 0)
 403                         dev_info(dev,
 404                            "tmr_margin value out of range, default %d used\n",
 405                                CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 406                 else
 407                         dev_info(dev, "default timer value is out of range, cannot start\n");
 408         }
 409
 410         ret = misc_register(&s3c2410wdt_miscdev);
 411         if (ret) {
 412                 dev_err(dev, "cannot register miscdev on minor=%d (%d)\n",
 413                         WATCHDOG_MINOR, ret);
 414                 goto err_clk;
 415         }
 416
 417         if (tmr_atboot && started == 0) {
 418                 dev_info(dev, "starting watchdog timer\n");
 419                 s3c2410wdt_start();
 420         } else if (!tmr_atboot) {
 421                 /* if we're not enabling the watchdog, then ensure it is
 422                  * disabled if it has been left running from the bootloader
 423                  * or other source */
 424
 425                 s3c2410wdt_stop();
 426         }
 427
 428         /* print out a statement of readiness */
 429
 430         wtcon = readl(wdt_base + S3C2410_WTCON);
 431
 432         dev_info(dev, "watchdog %sactive, reset %sabled, irq %sabled\n",
 433                  (wtcon & S3C2410_WTCON_ENABLE) ?  "" : "in",
 434                  (wtcon & S3C2410_WTCON_RSTEN) ? "" : "dis",
 435                  (wtcon & S3C2410_WTCON_INTEN) ? "" : "en");
 436
 437         return 0;
 438
 439  err_clk:
 440         clk_disable(wdt_clock);
 441         clk_put(wdt_clock);
 442
 443  err_irq:
 444         free_irq(wdt_irq->start, pdev);
 445
 446  err_map:
 447         iounmap(wdt_base);
 448
 449  err_req:
 450         release_resource(wdt_mem);
 451         kfree(wdt_mem);
 452
 453         return ret;
 454 }
 455
 456 static int s3c2410wdt_remove(struct platform_device *dev)
 457 {
 458         release_resource(wdt_mem);
 459         kfree(wdt_mem);
 460         wdt_mem = NULL;
 461
 462         free_irq(wdt_irq->start, dev);
 463         wdt_irq = NULL;
 464
 465         clk_disable(wdt_clock);
 466         clk_put(wdt_clock);
 467         wdt_clock = NULL;
 468
 469         iounmap(wdt_base);
 470         misc_deregister(&s3c2410wdt_miscdev);
 471         return 0;
 472 }
 473
 474 static void s3c2410wdt_shutdown(struct platform_device *dev)
 475 {
 476         s3c2410wdt_stop();
 477 }
 478
 479 #ifdef CONFIG_PM
 480
 481 static unsigned long wtcon_save;
 482 static unsigned long wtdat_save;
 483
 484 static int s3c2410wdt_suspend(struct platform_device *dev, pm_message_t state)
 485 {
 486         /* Save watchdog state, and turn it off. */
 487         wtcon_save = readl(wdt_base + S3C2410_WTCON);
 488         wtdat_save = readl(wdt_base + S3C2410_WTDAT);
 489
 490         /* Note that WTCNT doesn't need to be saved. */
 491         s3c2410wdt_stop();
 492
 493         return 0;
 494 }
 495
 496 static int s3c2410wdt_resume(struct platform_device *dev)
 497 {
 498         /* Restore watchdog state. */
 499
 500         writel(wtdat_save, wdt_base + S3C2410_WTDAT);
 501         writel(wtdat_save, wdt_base + S3C2410_WTCNT); /* Reset count */
 502         writel(wtcon_save, wdt_base + S3C2410_WTCON);
 503
 504         printk(KERN_INFO PFX "watchdog %sabled\n",
 505                (wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
 506
 507         return 0;
 508 }
 509
 510 #else
 511 #define s3c2410wdt_suspend NULL
 512 #define s3c2410wdt_resume  NULL
 513 #endif /* CONFIG_PM */
 514
 515
 516 static struct platform_driver s3c2410wdt_driver = {
 517         .probe          = s3c2410wdt_probe,
 518         .remove         = s3c2410wdt_remove,
 519         .shutdown       = s3c2410wdt_shutdown,
 520         .suspend        = s3c2410wdt_suspend,
 521         .resume         = s3c2410wdt_resume,
 522         .driver         = {
 523                 .owner  = THIS_MODULE,
 524                 .name   = "s3c2410-wdt",
 525         },
 526 };
 527
 528
 529 static char banner[] __initdata =
 530         KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n";
 531
 532 static int __init watchdog_init(void)
 533 {
 534         printk(banner);
 535         return platform_driver_register(&s3c2410wdt_driver);
 536 }
 537
 538 static void __exit watchdog_exit(void)
 539 {
 540         platform_driver_unregister(&s3c2410wdt_driver);
 541 }
 542
 543 module_init(watchdog_init);
 544 module_exit(watchdog_exit);
 545
 546 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "
 547               "Dimitry Andric <dimitry.andric@tomtom.com>");
 548 MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
 549 MODULE_LICENSE("GPL");
 550 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 551 MODULE_ALIAS("platform:s3c2410-wdt");