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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 <asm/arch/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         spin_lock(&wdt_lock);
 123         wtcon = readl(wdt_base + S3C2410_WTCON);
 124         wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
 125         writel(wtcon, wdt_base + S3C2410_WTCON);
 126         spin_unlock(&wdt_lock);
 127 }
 128
 129 static void __s3c2410wdt_stop(void)
 130 {
 131         unsigned long wtcon;
 132
 133         wtcon = readl(wdt_base + S3C2410_WTCON);
 134         wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
 135         writel(wtcon, wdt_base + S3C2410_WTCON);
 136 }
 137
 138 static void s3c2410wdt_stop(void)
 139 {
 140         spin_lock(&wdt_lock);
 141         __s3c2410wdt_stop();
 142         spin_unlock(&wdt_lock);
 143 }
 144
 145 static void s3c2410wdt_start(void)
 146 {
 147         unsigned long wtcon;
 148
 149         spin_lock(&wdt_lock);
 150
 151         __s3c2410wdt_stop();
 152
 153         wtcon = readl(wdt_base + S3C2410_WTCON);
 154         wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;
 155
 156         if (soft_noboot) {
 157                 wtcon |= S3C2410_WTCON_INTEN;
 158                 wtcon &= ~S3C2410_WTCON_RSTEN;
 159         } else {
 160                 wtcon &= ~S3C2410_WTCON_INTEN;
 161                 wtcon |= S3C2410_WTCON_RSTEN;
 162         }
 163
 164         DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
 165             __func__, wdt_count, wtcon);
 166
 167         writel(wdt_count, wdt_base + S3C2410_WTDAT);
 168         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 169         writel(wtcon, wdt_base + S3C2410_WTCON);
 170         spin_unlock(&wdt_lock);
 171
 172         return 0;
 173 }
 174
 175 static int s3c2410wdt_set_heartbeat(int timeout)
 176 {
 177         unsigned int freq = clk_get_rate(wdt_clock);
 178         unsigned int count;
 179         unsigned int divisor = 1;
 180         unsigned long wtcon;
 181
 182         if (timeout < 1)
 183                 return -EINVAL;
 184
 185         freq /= 128;
 186         count = timeout * freq;
 187
 188         DBG("%s: count=%d, timeout=%d, freq=%d\n",
 189             __func__, count, timeout, freq);
 190
 191         /* if the count is bigger than the watchdog register,
 192            then work out what we need to do (and if) we can
 193            actually make this value
 194         */
 195
 196         if (count >= 0x10000) {
 197                 for (divisor = 1; divisor <= 0x100; divisor++) {
 198                         if ((count / divisor) < 0x10000)
 199                                 break;
 200                 }
 201
 202                 if ((count / divisor) >= 0x10000) {
 203                         dev_err(wdt_dev, "timeout %d too big\n", timeout);
 204                         return -EINVAL;
 205                 }
 206         }
 207
 208         tmr_margin = timeout;
 209
 210         DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
 211             __func__, timeout, divisor, count, count/divisor);
 212
 213         count /= divisor;
 214         wdt_count = count;
 215
 216         /* update the pre-scaler */
 217         wtcon = readl(wdt_base + S3C2410_WTCON);
 218         wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
 219         wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);
 220
 221         writel(count, wdt_base + S3C2410_WTDAT);
 222         writel(wtcon, wdt_base + S3C2410_WTCON);
 223
 224         return 0;
 225 }
 226
 227 /*
 228  *      /dev/watchdog handling
 229  */
 230
 231 static int s3c2410wdt_open(struct inode *inode, struct file *file)
 232 {
 233         if (test_and_set_bit(0, &open_lock))
 234                 return -EBUSY;
 235
 236         if (nowayout)
 237                 __module_get(THIS_MODULE);
 238
 239         allow_close = CLOSE_STATE_NOT;
 240
 241         /* start the timer */
 242         s3c2410wdt_start();
 243         return nonseekable_open(inode, file);
 244 }
 245
 246 static int s3c2410wdt_release(struct inode *inode, struct file *file)
 247 {
 248         /*
 249          *      Shut off the timer.
 250          *      Lock it in if it's a module and we set nowayout
 251          */
 252
 253         if (allow_close == CLOSE_STATE_ALLOW)
 254                 s3c2410wdt_stop();
 255         else {
 256                 dev_err(wdt_dev, "Unexpected close, not stopping watchdog\n");
 257                 s3c2410wdt_keepalive();
 258         }
 259         allow_close = CLOSE_STATE_NOT;
 260         clear_bit(0, &open_lock);
 261         return 0;
 262 }
 263
 264 static ssize_t s3c2410wdt_write(struct file *file, const char __user *data,
 265                                 size_t len, loff_t *ppos)
 266 {
 267         /*
 268          *      Refresh the timer.
 269          */
 270         if (len) {
 271                 if (!nowayout) {
 272                         size_t i;
 273
 274                         /* In case it was set long ago */
 275                         allow_close = CLOSE_STATE_NOT;
 276
 277                         for (i = 0; i != len; i++) {
 278                                 char c;
 279
 280                                 if (get_user(c, data + i))
 281                                         return -EFAULT;
 282                                 if (c == 'V')
 283                                         allow_close = CLOSE_STATE_ALLOW;
 284                         }
 285                 }
 286                 s3c2410wdt_keepalive();
 287         }
 288         return len;
 289 }
 290
 291 #define OPTIONS WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE
 292
 293 static const struct watchdog_info s3c2410_wdt_ident = {
 294         .options          =     OPTIONS,
 295         .firmware_version =     0,
 296         .identity         =     "S3C2410 Watchdog",
 297 };
 298
 299
 300 static long s3c2410wdt_ioctl(struct file *file, unsigned int cmd,
 301                                                         unsigned long arg)
 302 {
 303         void __user *argp = (void __user *)arg;
 304         int __user *p = argp;
 305         int new_margin;
 306
 307         switch (cmd) {
 308         default:
 309                 return -ENOTTY;
 310         case WDIOC_GETSUPPORT:
 311                 return copy_to_user(argp, &s3c2410_wdt_ident,
 312                         sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0;
 313         case WDIOC_GETSTATUS:
 314         case WDIOC_GETBOOTSTATUS:
 315                 return put_user(0, p);
 316         case WDIOC_KEEPALIVE:
 317                 s3c2410wdt_keepalive();
 318                 return 0;
 319         case WDIOC_SETTIMEOUT:
 320                 if (get_user(new_margin, p))
 321                         return -EFAULT;
 322                 if (s3c2410wdt_set_heartbeat(new_margin))
 323                         return -EINVAL;
 324                 s3c2410wdt_keepalive();
 325                 return put_user(tmr_margin, p);
 326         case WDIOC_GETTIMEOUT:
 327                 return put_user(tmr_margin, p);
 328         }
 329 }
 330
 331 /* kernel interface */
 332
 333 static const struct file_operations s3c2410wdt_fops = {
 334         .owner          = THIS_MODULE,
 335         .llseek         = no_llseek,
 336         .write          = s3c2410wdt_write,
 337         .unlocked_ioctl = s3c2410wdt_ioctl,
 338         .open           = s3c2410wdt_open,
 339         .release        = s3c2410wdt_release,
 340 };
 341
 342 static struct miscdevice s3c2410wdt_miscdev = {
 343         .minor          = WATCHDOG_MINOR,
 344         .name           = "watchdog",
 345         .fops           = &s3c2410wdt_fops,
 346 };
 347
 348 /* interrupt handler code */
 349
 350 static irqreturn_t s3c2410wdt_irq(int irqno, void *param)
 351 {
 352         dev_info(wdt_dev, "watchdog timer expired (irq)\n");
 353
 354         s3c2410wdt_keepalive();
 355         return IRQ_HANDLED;
 356 }
 357 /* device interface */
 358
 359 static int s3c2410wdt_probe(struct platform_device *pdev)
 360 {
 361         struct resource *res;
 362         struct device *dev;
 363         unsigned int wtcon;
 364         int started = 0;
 365         int ret;
 366         int size;
 367
 368         DBG("%s: probe=%p\n", __func__, pdev);
 369
 370         dev = &pdev->dev;
 371         wdt_dev = &pdev->dev;
 372
 373         /* get the memory region for the watchdog timer */
 374
 375         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 376         if (res == NULL) {
 377                 dev_err(dev, "no memory resource specified\n");
 378                 return -ENOENT;
 379         }
 380
 381         size = (res->end-res->start)+1;
 382         wdt_mem = request_mem_region(res->start, size, pdev->name);
 383         if (wdt_mem == NULL) {
 384                 dev_err(dev, "failed to get memory region\n");
 385                 ret = -ENOENT;
 386                 goto err_req;
 387         }
 388
 389         wdt_base = ioremap(res->start, size);
 390         if (wdt_base == 0) {
 391                 dev_err(dev, "failed to ioremap() region\n");
 392                 ret = -EINVAL;
 393                 goto err_req;
 394         }
 395
 396         DBG("probe: mapped wdt_base=%p\n", wdt_base);
 397
 398         wdt_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 399         if (wdt_irq == NULL) {
 400                 dev_err(dev, "no irq resource specified\n");
 401                 ret = -ENOENT;
 402                 goto err_map;
 403         }
 404
 405         ret = request_irq(wdt_irq->start, s3c2410wdt_irq, 0, pdev->name, pdev);
 406         if (ret != 0) {
 407                 dev_err(dev, "failed to install irq (%d)\n", ret);
 408                 goto err_map;
 409         }
 410
 411         wdt_clock = clk_get(&pdev->dev, "watchdog");
 412         if (IS_ERR(wdt_clock)) {
 413                 dev_err(dev, "failed to find watchdog clock source\n");
 414                 ret = PTR_ERR(wdt_clock);
 415                 goto err_irq;
 416         }
 417
 418         clk_enable(wdt_clock);
 419
 420         /* see if we can actually set the requested timer margin, and if
 421          * not, try the default value */
 422
 423         if (s3c2410wdt_set_heartbeat(tmr_margin)) {
 424                 started = s3c2410wdt_set_heartbeat(
 425                                         CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 426
 427                 if (started == 0)
 428                         dev_info(dev,
 429                            "tmr_margin value out of range, default %d used\n",
 430                                CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 431                 else
 432                         dev_info(dev, "default timer value is out of range, cannot start\n");
 433         }
 434
 435         ret = misc_register(&s3c2410wdt_miscdev);
 436         if (ret) {
 437                 dev_err(dev, "cannot register miscdev on minor=%d (%d)\n",
 438                         WATCHDOG_MINOR, ret);
 439                 goto err_clk;
 440         }
 441
 442         if (tmr_atboot && started == 0) {
 443                 dev_info(dev, "starting watchdog timer\n");
 444                 s3c2410wdt_start();
 445         } else if (!tmr_atboot) {
 446                 /* if we're not enabling the watchdog, then ensure it is
 447                  * disabled if it has been left running from the bootloader
 448                  * or other source */
 449
 450                 s3c2410wdt_stop();
 451         }
 452
 453         /* print out a statement of readiness */
 454
 455         wtcon = readl(wdt_base + S3C2410_WTCON);
 456
 457         dev_info(dev, "watchdog %sactive, reset %sabled, irq %sabled\n",
 458                  (wtcon & S3C2410_WTCON_ENABLE) ?  "" : "in",
 459                  (wtcon & S3C2410_WTCON_RSTEN) ? "" : "dis",
 460                  (wtcon & S3C2410_WTCON_INTEN) ? "" : "en");
 461
 462         return 0;
 463
 464  err_clk:
 465         clk_disable(wdt_clock);
 466         clk_put(wdt_clock);
 467
 468  err_irq:
 469         free_irq(wdt_irq->start, pdev);
 470
 471  err_map:
 472         iounmap(wdt_base);
 473
 474  err_req:
 475         release_resource(wdt_mem);
 476         kfree(wdt_mem);
 477
 478         return ret;
 479 }
 480
 481 static int s3c2410wdt_remove(struct platform_device *dev)
 482 {
 483         release_resource(wdt_mem);
 484         kfree(wdt_mem);
 485         wdt_mem = NULL;
 486
 487         free_irq(wdt_irq->start, dev);
 488         wdt_irq = NULL;
 489
 490         clk_disable(wdt_clock);
 491         clk_put(wdt_clock);
 492         wdt_clock = NULL;
 493
 494         iounmap(wdt_base);
 495         misc_deregister(&s3c2410wdt_miscdev);
 496         return 0;
 497 }
 498
 499 static void s3c2410wdt_shutdown(struct platform_device *dev)
 500 {
 501         s3c2410wdt_stop();
 502 }
 503
 504 #ifdef CONFIG_PM
 505
 506 static unsigned long wtcon_save;
 507 static unsigned long wtdat_save;
 508
 509 static int s3c2410wdt_suspend(struct platform_device *dev, pm_message_t state)
 510 {
 511         /* Save watchdog state, and turn it off. */
 512         wtcon_save = readl(wdt_base + S3C2410_WTCON);
 513         wtdat_save = readl(wdt_base + S3C2410_WTDAT);
 514
 515         /* Note that WTCNT doesn't need to be saved. */
 516         s3c2410wdt_stop();
 517
 518         return 0;
 519 }
 520
 521 static int s3c2410wdt_resume(struct platform_device *dev)
 522 {
 523         /* Restore watchdog state. */
 524
 525         writel(wtdat_save, wdt_base + S3C2410_WTDAT);
 526         writel(wtdat_save, wdt_base + S3C2410_WTCNT); /* Reset count */
 527         writel(wtcon_save, wdt_base + S3C2410_WTCON);
 528
 529         printk(KERN_INFO PFX "watchdog %sabled\n",
 530                (wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
 531
 532         return 0;
 533 }
 534
 535 #else
 536 #define s3c2410wdt_suspend NULL
 537 #define s3c2410wdt_resume  NULL
 538 #endif /* CONFIG_PM */
 539
 540
 541 static struct platform_driver s3c2410wdt_driver = {
 542         .probe          = s3c2410wdt_probe,
 543         .remove         = s3c2410wdt_remove,
 544         .shutdown       = s3c2410wdt_shutdown,
 545         .suspend        = s3c2410wdt_suspend,
 546         .resume         = s3c2410wdt_resume,
 547         .driver         = {
 548                 .owner  = THIS_MODULE,
 549                 .name   = "s3c2410-wdt",
 550         },
 551 };
 552
 553
 554 static char banner[] __initdata =
 555         KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n";
 556
 557 static int __init watchdog_init(void)
 558 {
 559         printk(banner);
 560         return platform_driver_register(&s3c2410wdt_driver);
 561 }
 562
 563 static void __exit watchdog_exit(void)
 564 {
 565         platform_driver_unregister(&s3c2410wdt_driver);
 566 }
 567
 568 module_init(watchdog_init);
 569 module_exit(watchdog_exit);
 570
 571 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "
 572               "Dimitry Andric <dimitry.andric@tomtom.com>");
 573 MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
 574 MODULE_LICENSE("GPL");
 575 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 576 MODULE_ALIAS("platform:s3c2410-wdt");