drivers/watchdog/s3c2410_wdt.c

   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 #include <linux/cpufreq.h>
  40 #include <linux/slab.h>
  41
  42 #include <mach/map.h>
  43
  44 #undef S3C_VA_WATCHDOG
  45 #define S3C_VA_WATCHDOG (0)
  46
  47 #include <plat/regs-watchdog.h>
  48
  49 #define PFX "s3c2410-wdt: "
  50
  51 #define CONFIG_S3C2410_WATCHDOG_ATBOOT          (0)
  52 #define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME    (15)
  53
  54 static int nowayout     = WATCHDOG_NOWAYOUT;
  55 static int tmr_margin   = CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME;
  56 static int tmr_atboot   = CONFIG_S3C2410_WATCHDOG_ATBOOT;
  57 static int soft_noboot;
  58 static int debug;
  59
  60 module_param(tmr_margin,  int, 0);
  61 module_param(tmr_atboot,  int, 0);
  62 module_param(nowayout,    int, 0);
  63 module_param(soft_noboot, int, 0);
  64 module_param(debug,       int, 0);
  65
  66 MODULE_PARM_DESC(tmr_margin, "Watchdog tmr_margin in seconds. (default="
  67                 __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME) ")");
  68 MODULE_PARM_DESC(tmr_atboot,
  69                 "Watchdog is started at boot time if set to 1, default="
  70                         __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_ATBOOT));
  71 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  72                         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  73 MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, "
  74                         "0 to reboot (default 0)");
  75 MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug (default 0)");
  76
  77 static unsigned long open_lock;
  78 static struct device    *wdt_dev;       /* platform device attached to */
  79 static struct resource  *wdt_mem;
  80 static struct resource  *wdt_irq;
  81 static struct clk       *wdt_clock;
  82 static void __iomem     *wdt_base;
  83 static unsigned int      wdt_count;
  84 static char              expect_close;
  85 static DEFINE_SPINLOCK(wdt_lock);
  86
  87 /* watchdog control routines */
  88
  89 #define DBG(msg...) do { \
  90         if (debug) \
  91                 printk(KERN_INFO msg); \
  92         } while (0)
  93
  94 /* functions */
  95
  96 static void s3c2410wdt_keepalive(void)
  97 {
  98         spin_lock(&wdt_lock);
  99         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 100         spin_unlock(&wdt_lock);
 101 }
 102
 103 static void __s3c2410wdt_stop(void)
 104 {
 105         unsigned long wtcon;
 106
 107         wtcon = readl(wdt_base + S3C2410_WTCON);
 108         wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
 109         writel(wtcon, wdt_base + S3C2410_WTCON);
 110 }
 111
 112 static void s3c2410wdt_stop(void)
 113 {
 114         spin_lock(&wdt_lock);
 115         __s3c2410wdt_stop();
 116         spin_unlock(&wdt_lock);
 117 }
 118
 119 static void s3c2410wdt_start(void)
 120 {
 121         unsigned long wtcon;
 122
 123         spin_lock(&wdt_lock);
 124
 125         __s3c2410wdt_stop();
 126
 127         wtcon = readl(wdt_base + S3C2410_WTCON);
 128         wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;
 129
 130         if (soft_noboot) {
 131                 wtcon |= S3C2410_WTCON_INTEN;
 132                 wtcon &= ~S3C2410_WTCON_RSTEN;
 133         } else {
 134                 wtcon &= ~S3C2410_WTCON_INTEN;
 135                 wtcon |= S3C2410_WTCON_RSTEN;
 136         }
 137
 138         DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
 139             __func__, wdt_count, wtcon);
 140
 141         writel(wdt_count, wdt_base + S3C2410_WTDAT);
 142         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 143         writel(wtcon, wdt_base + S3C2410_WTCON);
 144         spin_unlock(&wdt_lock);
 145 }
 146
 147 static inline int s3c2410wdt_is_running(void)
 148 {
 149         return readl(wdt_base + S3C2410_WTCON) & S3C2410_WTCON_ENABLE;
 150 }
 151
 152 static int s3c2410wdt_set_heartbeat(int timeout)
 153 {
 154         unsigned long freq = clk_get_rate(wdt_clock);
 155         unsigned int count;
 156         unsigned int divisor = 1;
 157         unsigned long wtcon;
 158
 159         if (timeout < 1)
 160                 return -EINVAL;
 161
 162         freq /= 128;
 163         count = timeout * freq;
 164
 165         DBG("%s: count=%d, timeout=%d, freq=%lu\n",
 166             __func__, count, timeout, freq);
 167
 168         /* if the count is bigger than the watchdog register,
 169            then work out what we need to do (and if) we can
 170            actually make this value
 171         */
 172
 173         if (count >= 0x10000) {
 174                 for (divisor = 1; divisor <= 0x100; divisor++) {
 175                         if ((count / divisor) < 0x10000)
 176                                 break;
 177                 }
 178
 179                 if ((count / divisor) >= 0x10000) {
 180                         dev_err(wdt_dev, "timeout %d too big\n", timeout);
 181                         return -EINVAL;
 182                 }
 183         }
 184
 185         tmr_margin = timeout;
 186
 187         DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
 188             __func__, timeout, divisor, count, count/divisor);
 189
 190         count /= divisor;
 191         wdt_count = count;
 192
 193         /* update the pre-scaler */
 194         wtcon = readl(wdt_base + S3C2410_WTCON);
 195         wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
 196         wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);
 197
 198         writel(count, wdt_base + S3C2410_WTDAT);
 199         writel(wtcon, wdt_base + S3C2410_WTCON);
 200
 201         return 0;
 202 }
 203
 204 /*
 205  *      /dev/watchdog handling
 206  */
 207
 208 static int s3c2410wdt_open(struct inode *inode, struct file *file)
 209 {
 210         if (test_and_set_bit(0, &open_lock))
 211                 return -EBUSY;
 212
 213         if (nowayout)
 214                 __module_get(THIS_MODULE);
 215
 216         expect_close = 0;
 217
 218         /* start the timer */
 219         s3c2410wdt_start();
 220         return nonseekable_open(inode, file);
 221 }
 222
 223 static int s3c2410wdt_release(struct inode *inode, struct file *file)
 224 {
 225         /*
 226          *      Shut off the timer.
 227          *      Lock it in if it's a module and we set nowayout
 228          */
 229
 230         if (expect_close == 42)
 231                 s3c2410wdt_stop();
 232         else {
 233                 dev_err(wdt_dev, "Unexpected close, not stopping watchdog\n");
 234                 s3c2410wdt_keepalive();
 235         }
 236         expect_close = 0;
 237         clear_bit(0, &open_lock);
 238         return 0;
 239 }
 240
 241 static ssize_t s3c2410wdt_write(struct file *file, const char __user *data,
 242                                 size_t len, loff_t *ppos)
 243 {
 244         /*
 245          *      Refresh the timer.
 246          */
 247         if (len) {
 248                 if (!nowayout) {
 249                         size_t i;
 250
 251                         /* In case it was set long ago */
 252                         expect_close = 0;
 253
 254                         for (i = 0; i != len; i++) {
 255                                 char c;
 256
 257                                 if (get_user(c, data + i))
 258                                         return -EFAULT;
 259                                 if (c == 'V')
 260                                         expect_close = 42;
 261                         }
 262                 }
 263                 s3c2410wdt_keepalive();
 264         }
 265         return len;
 266 }
 267
 268 #define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
 269
 270 static const struct watchdog_info s3c2410_wdt_ident = {
 271         .options          =     OPTIONS,
 272         .firmware_version =     0,
 273         .identity         =     "S3C2410 Watchdog",
 274 };
 275
 276
 277 static long s3c2410wdt_ioctl(struct file *file, unsigned int cmd,
 278                                                         unsigned long arg)
 279 {
 280         void __user *argp = (void __user *)arg;
 281         int __user *p = argp;
 282         int new_margin;
 283
 284         switch (cmd) {
 285         case WDIOC_GETSUPPORT:
 286                 return copy_to_user(argp, &s3c2410_wdt_ident,
 287                         sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0;
 288         case WDIOC_GETSTATUS:
 289         case WDIOC_GETBOOTSTATUS:
 290                 return put_user(0, p);
 291         case WDIOC_KEEPALIVE:
 292                 s3c2410wdt_keepalive();
 293                 return 0;
 294         case WDIOC_SETTIMEOUT:
 295                 if (get_user(new_margin, p))
 296                         return -EFAULT;
 297                 if (s3c2410wdt_set_heartbeat(new_margin))
 298                         return -EINVAL;
 299                 s3c2410wdt_keepalive();
 300                 return put_user(tmr_margin, p);
 301         case WDIOC_GETTIMEOUT:
 302                 return put_user(tmr_margin, p);
 303         default:
 304                 return -ENOTTY;
 305         }
 306 }
 307
 308 /* kernel interface */
 309
 310 static const struct file_operations s3c2410wdt_fops = {
 311         .owner          = THIS_MODULE,
 312         .llseek         = no_llseek,
 313         .write          = s3c2410wdt_write,
 314         .unlocked_ioctl = s3c2410wdt_ioctl,
 315         .open           = s3c2410wdt_open,
 316         .release        = s3c2410wdt_release,
 317 };
 318
 319 static struct miscdevice s3c2410wdt_miscdev = {
 320         .minor          = WATCHDOG_MINOR,
 321         .name           = "watchdog",
 322         .fops           = &s3c2410wdt_fops,
 323 };
 324
 325 /* interrupt handler code */
 326
 327 static irqreturn_t s3c2410wdt_irq(int irqno, void *param)
 328 {
 329         dev_info(wdt_dev, "watchdog timer expired (irq)\n");
 330
 331         s3c2410wdt_keepalive();
 332         return IRQ_HANDLED;
 333 }
 334
 335
 336 #ifdef CONFIG_CPU_FREQ
 337
 338 static int s3c2410wdt_cpufreq_transition(struct notifier_block *nb,
 339                                           unsigned long val, void *data)
 340 {
 341         int ret;
 342
 343         if (!s3c2410wdt_is_running())
 344                 goto done;
 345
 346         if (val == CPUFREQ_PRECHANGE) {
 347                 /* To ensure that over the change we don't cause the
 348                  * watchdog to trigger, we perform an keep-alive if
 349                  * the watchdog is running.
 350                  */
 351
 352                 s3c2410wdt_keepalive();
 353         } else if (val == CPUFREQ_POSTCHANGE) {
 354                 s3c2410wdt_stop();
 355
 356                 ret = s3c2410wdt_set_heartbeat(tmr_margin);
 357
 358                 if (ret >= 0)
 359                         s3c2410wdt_start();
 360                 else
 361                         goto err;
 362         }
 363
 364 done:
 365         return 0;
 366
 367  err:
 368         dev_err(wdt_dev, "cannot set new value for timeout %d\n", tmr_margin);
 369         return ret;
 370 }
 371
 372 static struct notifier_block s3c2410wdt_cpufreq_transition_nb = {
 373         .notifier_call  = s3c2410wdt_cpufreq_transition,
 374 };
 375
 376 static inline int s3c2410wdt_cpufreq_register(void)
 377 {
 378         return cpufreq_register_notifier(&s3c2410wdt_cpufreq_transition_nb,
 379                                          CPUFREQ_TRANSITION_NOTIFIER);
 380 }
 381
 382 static inline void s3c2410wdt_cpufreq_deregister(void)
 383 {
 384         cpufreq_unregister_notifier(&s3c2410wdt_cpufreq_transition_nb,
 385                                     CPUFREQ_TRANSITION_NOTIFIER);
 386 }
 387
 388 #else
 389 static inline int s3c2410wdt_cpufreq_register(void)
 390 {
 391         return 0;
 392 }
 393
 394 static inline void s3c2410wdt_cpufreq_deregister(void)
 395 {
 396 }
 397 #endif
 398
 399
 400
 401 /* device interface */
 402
 403 static int __devinit s3c2410wdt_probe(struct platform_device *pdev)
 404 {
 405         struct device *dev;
 406         unsigned int wtcon;
 407         int started = 0;
 408         int ret;
 409         int size;
 410
 411         DBG("%s: probe=%p\n", __func__, pdev);
 412
 413         dev = &pdev->dev;
 414         wdt_dev = &pdev->dev;
 415
 416         /* get the memory region for the watchdog timer */
 417
 418         wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 419         if (wdt_mem == NULL) {
 420                 dev_err(dev, "no memory resource specified\n");
 421                 return -ENOENT;
 422         }
 423
 424         size = resource_size(wdt_mem);
 425         if (!request_mem_region(wdt_mem->start, size, pdev->name)) {
 426                 dev_err(dev, "failed to get memory region\n");
 427                 return -EBUSY;
 428         }
 429
 430         wdt_base = ioremap(wdt_mem->start, size);
 431         if (wdt_base == NULL) {
 432                 dev_err(dev, "failed to ioremap() region\n");
 433                 ret = -EINVAL;
 434                 goto err_req;
 435         }
 436
 437         DBG("probe: mapped wdt_base=%p\n", wdt_base);
 438
 439         wdt_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 440         if (wdt_irq == NULL) {
 441                 dev_err(dev, "no irq resource specified\n");
 442                 ret = -ENOENT;
 443                 goto err_map;
 444         }
 445
 446         ret = request_irq(wdt_irq->start, s3c2410wdt_irq, 0, pdev->name, pdev);
 447         if (ret != 0) {
 448                 dev_err(dev, "failed to install irq (%d)\n", ret);
 449                 goto err_map;
 450         }
 451
 452         wdt_clock = clk_get(&pdev->dev, "watchdog");
 453         if (IS_ERR(wdt_clock)) {
 454                 dev_err(dev, "failed to find watchdog clock source\n");
 455                 ret = PTR_ERR(wdt_clock);
 456                 goto err_irq;
 457         }
 458
 459         clk_enable(wdt_clock);
 460
 461         if (s3c2410wdt_cpufreq_register() < 0) {
 462                 printk(KERN_ERR PFX "failed to register cpufreq\n");
 463                 goto err_clk;
 464         }
 465
 466         /* see if we can actually set the requested timer margin, and if
 467          * not, try the default value */
 468
 469         if (s3c2410wdt_set_heartbeat(tmr_margin)) {
 470                 started = s3c2410wdt_set_heartbeat(
 471                                         CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 472
 473                 if (started == 0)
 474                         dev_info(dev,
 475                            "tmr_margin value out of range, default %d used\n",
 476                                CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 477                 else
 478                         dev_info(dev, "default timer value is out of range, "
 479                                                         "cannot start\n");
 480         }
 481
 482         ret = misc_register(&s3c2410wdt_miscdev);
 483         if (ret) {
 484                 dev_err(dev, "cannot register miscdev on minor=%d (%d)\n",
 485                         WATCHDOG_MINOR, ret);
 486                 goto err_cpufreq;
 487         }
 488
 489         if (tmr_atboot && started == 0) {
 490                 dev_info(dev, "starting watchdog timer\n");
 491                 s3c2410wdt_start();
 492         } else if (!tmr_atboot) {
 493                 /* if we're not enabling the watchdog, then ensure it is
 494                  * disabled if it has been left running from the bootloader
 495                  * or other source */
 496
 497                 s3c2410wdt_stop();
 498         }
 499
 500         /* print out a statement of readiness */
 501
 502         wtcon = readl(wdt_base + S3C2410_WTCON);
 503
 504         dev_info(dev, "watchdog %sactive, reset %sabled, irq %sabled\n",
 505                  (wtcon & S3C2410_WTCON_ENABLE) ?  "" : "in",
 506                  (wtcon & S3C2410_WTCON_RSTEN) ? "" : "dis",
 507                  (wtcon & S3C2410_WTCON_INTEN) ? "" : "en");
 508
 509         return 0;
 510
 511  err_cpufreq:
 512         s3c2410wdt_cpufreq_deregister();
 513
 514  err_clk:
 515         clk_disable(wdt_clock);
 516         clk_put(wdt_clock);
 517
 518  err_irq:
 519         free_irq(wdt_irq->start, pdev);
 520
 521  err_map:
 522         iounmap(wdt_base);
 523
 524  err_req:
 525         release_mem_region(wdt_mem->start, size);
 526         wdt_mem = NULL;
 527
 528         return ret;
 529 }
 530
 531 static int __devexit s3c2410wdt_remove(struct platform_device *dev)
 532 {
 533         misc_deregister(&s3c2410wdt_miscdev);
 534
 535         s3c2410wdt_cpufreq_deregister();
 536
 537         clk_disable(wdt_clock);
 538         clk_put(wdt_clock);
 539         wdt_clock = NULL;
 540
 541         free_irq(wdt_irq->start, dev);
 542         wdt_irq = NULL;
 543
 544         iounmap(wdt_base);
 545
 546         release_mem_region(wdt_mem->start, resource_size(wdt_mem));
 547         wdt_mem = NULL;
 548         return 0;
 549 }
 550
 551 static void s3c2410wdt_shutdown(struct platform_device *dev)
 552 {
 553         s3c2410wdt_stop();
 554 }
 555
 556 #ifdef CONFIG_PM
 557
 558 static unsigned long wtcon_save;
 559 static unsigned long wtdat_save;
 560
 561 static int s3c2410wdt_suspend(struct platform_device *dev, pm_message_t state)
 562 {
 563         /* Save watchdog state, and turn it off. */
 564         wtcon_save = readl(wdt_base + S3C2410_WTCON);
 565         wtdat_save = readl(wdt_base + S3C2410_WTDAT);
 566
 567         /* Note that WTCNT doesn't need to be saved. */
 568         s3c2410wdt_stop();
 569
 570         return 0;
 571 }
 572
 573 static int s3c2410wdt_resume(struct platform_device *dev)
 574 {
 575         /* Restore watchdog state. */
 576
 577         writel(wtdat_save, wdt_base + S3C2410_WTDAT);
 578         writel(wtdat_save, wdt_base + S3C2410_WTCNT); /* Reset count */
 579         writel(wtcon_save, wdt_base + S3C2410_WTCON);
 580
 581         printk(KERN_INFO PFX "watchdog %sabled\n",
 582                (wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
 583
 584         return 0;
 585 }
 586
 587 #else
 588 #define s3c2410wdt_suspend NULL
 589 #define s3c2410wdt_resume  NULL
 590 #endif /* CONFIG_PM */
 591
 592 #ifdef CONFIG_OF
 593 static const struct of_device_id s3c2410_wdt_match[] = {
 594         { .compatible = "samsung,s3c2410-wdt" },
 595         {},
 596 };
 597 MODULE_DEVICE_TABLE(of, s3c2410_wdt_match);
 598 #else
 599 #define s3c2410_wdt_match NULL
 600 #endif
 601
 602 static struct platform_driver s3c2410wdt_driver = {
 603         .probe          = s3c2410wdt_probe,
 604         .remove         = __devexit_p(s3c2410wdt_remove),
 605         .shutdown       = s3c2410wdt_shutdown,
 606         .suspend        = s3c2410wdt_suspend,
 607         .resume         = s3c2410wdt_resume,
 608         .driver         = {
 609                 .owner  = THIS_MODULE,
 610                 .name   = "s3c2410-wdt",
 611                 .of_match_table = s3c2410_wdt_match,
 612         },
 613 };
 614
 615
 616 static char banner[] __initdata =
 617         KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n";
 618
 619 static int __init watchdog_init(void)
 620 {
 621         printk(banner);
 622         return platform_driver_register(&s3c2410wdt_driver);
 623 }
 624
 625 static void __exit watchdog_exit(void)
 626 {
 627         platform_driver_unregister(&s3c2410wdt_driver);
 628 }
 629
 630 module_init(watchdog_init);
 631 module_exit(watchdog_exit);
 632
 633 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "
 634               "Dimitry Andric <dimitry.andric@tomtom.com>");
 635 MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
 636 MODULE_LICENSE("GPL");
 637 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 638 MODULE_ALIAS("platform:s3c2410-wdt");