drivers/char/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@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/config.h>
  41 #include <linux/types.h>
  42 #include <linux/timer.h>
  43 #include <linux/miscdevice.h>
  44 #include <linux/watchdog.h>
  45 #include <linux/fs.h>
  46 #include <linux/init.h>
  47 #include <linux/platform_device.h>
  48 #include <linux/interrupt.h>
  49
  50 #include <asm/uaccess.h>
  51 #include <asm/io.h>
  52
  53 #include <asm/arch/map.h>
  54 #include <asm/hardware/clock.h>
  55
  56 #undef S3C24XX_VA_WATCHDOG
  57 #define S3C24XX_VA_WATCHDOG (0)
  58
  59 #include <asm/arch/regs-watchdog.h>
  60
  61 #define PFX "s3c2410-wdt: "
  62
  63 #define CONFIG_S3C2410_WATCHDOG_ATBOOT          (0)
  64 #define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME    (15)
  65
  66 static int nowayout = WATCHDOG_NOWAYOUT;
  67 static int tmr_margin   = CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME;
  68 static int tmr_atboot   = CONFIG_S3C2410_WATCHDOG_ATBOOT;
  69 static int soft_noboot  = 0;
  70 static int debug        = 0;
  71
  72 module_param(tmr_margin,  int, 0);
  73 module_param(tmr_atboot,  int, 0);
  74 module_param(nowayout,    int, 0);
  75 module_param(soft_noboot, int, 0);
  76 module_param(debug,       int, 0);
  77
  78 MODULE_PARM_DESC(tmr_margin, "Watchdog tmr_margin in seconds. default=" __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME) ")");
  79
  80 MODULE_PARM_DESC(tmr_atboot, "Watchdog is started at boot time if set to 1, default=" __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_ATBOOT));
  81
  82 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
  83
  84 MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)");
  85
  86 MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug, (default 0)");
  87
  88
  89 typedef enum close_state {
  90         CLOSE_STATE_NOT,
  91         CLOSE_STATE_ALLOW=0x4021
  92 } close_state_t;
  93
  94 static DECLARE_MUTEX(open_lock);
  95
  96 static struct resource  *wdt_mem;
  97 static struct resource  *wdt_irq;
  98 static struct clk       *wdt_clock;
  99 static void __iomem     *wdt_base;
 100 static unsigned int      wdt_count;
 101 static close_state_t     allow_close;
 102
 103 /* watchdog control routines */
 104
 105 #define DBG(msg...) do { \
 106         if (debug) \
 107                 printk(KERN_INFO msg); \
 108         } while(0)
 109
 110 /* functions */
 111
 112 static int s3c2410wdt_keepalive(void)
 113 {
 114         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 115         return 0;
 116 }
 117
 118 static int 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         return 0;
 127 }
 128
 129 static int s3c2410wdt_start(void)
 130 {
 131         unsigned long wtcon;
 132
 133         s3c2410wdt_stop();
 134
 135         wtcon = readl(wdt_base + S3C2410_WTCON);
 136         wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;
 137
 138         if (soft_noboot) {
 139                 wtcon |= S3C2410_WTCON_INTEN;
 140                 wtcon &= ~S3C2410_WTCON_RSTEN;
 141         } else {
 142                 wtcon &= ~S3C2410_WTCON_INTEN;
 143                 wtcon |= S3C2410_WTCON_RSTEN;
 144         }
 145
 146         DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
 147             __FUNCTION__, wdt_count, wtcon);
 148
 149         writel(wdt_count, wdt_base + S3C2410_WTDAT);
 150         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 151         writel(wtcon, wdt_base + S3C2410_WTCON);
 152
 153         return 0;
 154 }
 155
 156 static int s3c2410wdt_set_heartbeat(int timeout)
 157 {
 158         unsigned int freq = clk_get_rate(wdt_clock);
 159         unsigned int count;
 160         unsigned int divisor = 1;
 161         unsigned long wtcon;
 162
 163         if (timeout < 1)
 164                 return -EINVAL;
 165
 166         freq /= 128;
 167         count = timeout * freq;
 168
 169         DBG("%s: count=%d, timeout=%d, freq=%d\n",
 170             __FUNCTION__, count, timeout, freq);
 171
 172         /* if the count is bigger than the watchdog register,
 173            then work out what we need to do (and if) we can
 174            actually make this value
 175         */
 176
 177         if (count >= 0x10000) {
 178                 for (divisor = 1; divisor <= 0x100; divisor++) {
 179                         if ((count / divisor) < 0x10000)
 180                                 break;
 181                 }
 182
 183                 if ((count / divisor) >= 0x10000) {
 184                         printk(KERN_ERR PFX "timeout %d too big\n", timeout);
 185                         return -EINVAL;
 186                 }
 187         }
 188
 189         tmr_margin = timeout;
 190
 191         DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
 192             __FUNCTION__, timeout, divisor, count, count/divisor);
 193
 194         count /= divisor;
 195         wdt_count = count;
 196
 197         /* update the pre-scaler */
 198         wtcon = readl(wdt_base + S3C2410_WTCON);
 199         wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
 200         wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);
 201
 202         writel(count, wdt_base + S3C2410_WTDAT);
 203         writel(wtcon, wdt_base + S3C2410_WTCON);
 204
 205         return 0;
 206 }
 207
 208 /*
 209  *      /dev/watchdog handling
 210  */
 211
 212 static int s3c2410wdt_open(struct inode *inode, struct file *file)
 213 {
 214         if(down_trylock(&open_lock))
 215                 return -EBUSY;
 216
 217         if (nowayout) {
 218                 __module_get(THIS_MODULE);
 219         } else {
 220                 allow_close = CLOSE_STATE_ALLOW;
 221         }
 222
 223         /* start the timer */
 224         s3c2410wdt_start();
 225         return nonseekable_open(inode, file);
 226 }
 227
 228 static int s3c2410wdt_release(struct inode *inode, struct file *file)
 229 {
 230         /*
 231          *      Shut off the timer.
 232          *      Lock it in if it's a module and we set nowayout
 233          */
 234         if (allow_close == CLOSE_STATE_ALLOW) {
 235                 s3c2410wdt_stop();
 236         } else {
 237                 printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
 238                 s3c2410wdt_keepalive();
 239         }
 240
 241         allow_close = CLOSE_STATE_NOT;
 242         up(&open_lock);
 243         return 0;
 244 }
 245
 246 static ssize_t s3c2410wdt_write(struct file *file, const char __user *data,
 247                                 size_t len, loff_t *ppos)
 248 {
 249         /*
 250          *      Refresh the timer.
 251          */
 252         if(len) {
 253                 if (!nowayout) {
 254                         size_t i;
 255
 256                         /* In case it was set long ago */
 257                         allow_close = CLOSE_STATE_NOT;
 258
 259                         for (i = 0; i != len; i++) {
 260                                 char c;
 261
 262                                 if (get_user(c, data + i))
 263                                         return -EFAULT;
 264                                 if (c == 'V')
 265                                         allow_close = CLOSE_STATE_ALLOW;
 266                         }
 267                 }
 268
 269                 s3c2410wdt_keepalive();
 270         }
 271         return len;
 272 }
 273
 274 #define OPTIONS WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE
 275
 276 static struct watchdog_info s3c2410_wdt_ident = {
 277         .options          =     OPTIONS,
 278         .firmware_version =     0,
 279         .identity         =     "S3C2410 Watchdog",
 280 };
 281
 282
 283 static int s3c2410wdt_ioctl(struct inode *inode, struct file *file,
 284         unsigned int cmd, unsigned long arg)
 285 {
 286         void __user *argp = (void __user *)arg;
 287         int __user *p = argp;
 288         int new_margin;
 289
 290         switch (cmd) {
 291                 default:
 292                         return -ENOIOCTLCMD;
 293
 294                 case WDIOC_GETSUPPORT:
 295                         return copy_to_user(argp, &s3c2410_wdt_ident,
 296                                 sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0;
 297
 298                 case WDIOC_GETSTATUS:
 299                 case WDIOC_GETBOOTSTATUS:
 300                         return put_user(0, p);
 301
 302                 case WDIOC_KEEPALIVE:
 303                         s3c2410wdt_keepalive();
 304                         return 0;
 305
 306                 case WDIOC_SETTIMEOUT:
 307                         if (get_user(new_margin, p))
 308                                 return -EFAULT;
 309
 310                         if (s3c2410wdt_set_heartbeat(new_margin))
 311                                 return -EINVAL;
 312
 313                         s3c2410wdt_keepalive();
 314                         return put_user(tmr_margin, p);
 315
 316                 case WDIOC_GETTIMEOUT:
 317                         return put_user(tmr_margin, p);
 318         }
 319 }
 320
 321 /* kernel interface */
 322
 323 static struct file_operations s3c2410wdt_fops = {
 324         .owner          = THIS_MODULE,
 325         .llseek         = no_llseek,
 326         .write          = s3c2410wdt_write,
 327         .ioctl          = s3c2410wdt_ioctl,
 328         .open           = s3c2410wdt_open,
 329         .release        = s3c2410wdt_release,
 330 };
 331
 332 static struct miscdevice s3c2410wdt_miscdev = {
 333         .minor          = WATCHDOG_MINOR,
 334         .name           = "watchdog",
 335         .fops           = &s3c2410wdt_fops,
 336 };
 337
 338 /* interrupt handler code */
 339
 340 static irqreturn_t s3c2410wdt_irq(int irqno, void *param,
 341                                   struct pt_regs *regs)
 342 {
 343         printk(KERN_INFO PFX "Watchdog timer expired!\n");
 344
 345         s3c2410wdt_keepalive();
 346         return IRQ_HANDLED;
 347 }
 348 /* device interface */
 349
 350 static int s3c2410wdt_probe(struct device *dev)
 351 {
 352         struct platform_device *pdev = to_platform_device(dev);
 353         struct resource *res;
 354         int started = 0;
 355         int ret;
 356         int size;
 357
 358         DBG("%s: probe=%p, device=%p\n", __FUNCTION__, 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                 printk(KERN_INFO PFX "failed to get memory region resouce\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                 printk(KERN_INFO PFX "failed to get memory region\n");
 372                 return -ENOENT;
 373         }
 374
 375         wdt_base = ioremap(res->start, size);
 376         if (wdt_base == 0) {
 377                 printk(KERN_INFO PFX "failed to ioremap() region\n");
 378                 return -EINVAL;
 379         }
 380
 381         DBG("probe: mapped wdt_base=%p\n", wdt_base);
 382
 383         res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 384         if (res == NULL) {
 385                 printk(KERN_INFO PFX "failed to get irq resource\n");
 386                 return -ENOENT;
 387         }
 388
 389         ret = request_irq(res->start, s3c2410wdt_irq, 0, pdev->name, dev);
 390         if (ret != 0) {
 391                 printk(KERN_INFO PFX "failed to install irq (%d)\n", ret);
 392                 return ret;
 393         }
 394
 395         wdt_clock = clk_get(dev, "watchdog");
 396         if (wdt_clock == NULL) {
 397                 printk(KERN_INFO PFX "failed to find watchdog clock source\n");
 398                 return -ENOENT;
 399         }
 400
 401         clk_use(wdt_clock);
 402         clk_enable(wdt_clock);
 403
 404         /* see if we can actually set the requested timer margin, and if
 405          * not, try the default value */
 406
 407         if (s3c2410wdt_set_heartbeat(tmr_margin)) {
 408                 started = s3c2410wdt_set_heartbeat(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 409
 410                 if (started == 0) {
 411                         printk(KERN_INFO PFX "tmr_margin value out of range, default %d used\n",
 412                                CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 413                 } else {
 414                         printk(KERN_INFO PFX "default timer value is out of range, cannot start\n");
 415                 }
 416         }
 417
 418         ret = misc_register(&s3c2410wdt_miscdev);
 419         if (ret) {
 420                 printk (KERN_ERR PFX "cannot register miscdev on minor=%d (%d)\n",
 421                         WATCHDOG_MINOR, ret);
 422                 return ret;
 423         }
 424
 425         if (tmr_atboot && started == 0) {
 426                 printk(KERN_INFO PFX "Starting Watchdog Timer\n");
 427                 s3c2410wdt_start();
 428         }
 429
 430         return 0;
 431 }
 432
 433 static int s3c2410wdt_remove(struct device *dev)
 434 {
 435         if (wdt_mem != NULL) {
 436                 release_resource(wdt_mem);
 437                 kfree(wdt_mem);
 438                 wdt_mem = NULL;
 439         }
 440
 441         if (wdt_irq != NULL) {
 442                 free_irq(wdt_irq->start, dev);
 443                 wdt_irq = NULL;
 444         }
 445
 446         if (wdt_clock != NULL) {
 447                 clk_disable(wdt_clock);
 448                 clk_unuse(wdt_clock);
 449                 clk_put(wdt_clock);
 450                 wdt_clock = NULL;
 451         }
 452
 453         misc_deregister(&s3c2410wdt_miscdev);
 454         return 0;
 455 }
 456
 457 static void s3c2410wdt_shutdown(struct device *dev)
 458 {
 459         s3c2410wdt_stop();
 460 }
 461
 462 #ifdef CONFIG_PM
 463
 464 static unsigned long wtcon_save;
 465 static unsigned long wtdat_save;
 466
 467 static int s3c2410wdt_suspend(struct device *dev, pm_message_t state)
 468 {
 469         /* Save watchdog state, and turn it off. */
 470         wtcon_save = readl(wdt_base + S3C2410_WTCON);
 471         wtdat_save = readl(wdt_base + S3C2410_WTDAT);
 472
 473         /* Note that WTCNT doesn't need to be saved. */
 474         s3c2410wdt_stop();
 475
 476         return 0;
 477 }
 478
 479 static int s3c2410wdt_resume(struct device *dev)
 480 {
 481         /* Restore watchdog state. */
 482
 483         writel(wtdat_save, wdt_base + S3C2410_WTDAT);
 484         writel(wtdat_save, wdt_base + S3C2410_WTCNT); /* Reset count */
 485         writel(wtcon_save, wdt_base + S3C2410_WTCON);
 486
 487         printk(KERN_INFO PFX "watchdog %sabled\n",
 488                (wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
 489
 490         return 0;
 491 }
 492
 493 #else
 494 #define s3c2410wdt_suspend NULL
 495 #define s3c2410wdt_resume  NULL
 496 #endif /* CONFIG_PM */
 497
 498
 499 static struct device_driver s3c2410wdt_driver = {
 500         .name           = "s3c2410-wdt",
 501         .bus            = &platform_bus_type,
 502         .probe          = s3c2410wdt_probe,
 503         .remove         = s3c2410wdt_remove,
 504         .shutdown       = s3c2410wdt_shutdown,
 505         .suspend        = s3c2410wdt_suspend,
 506         .resume         = s3c2410wdt_resume,
 507 };
 508
 509
 510 static char banner[] __initdata = KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n";
 511
 512 static int __init watchdog_init(void)
 513 {
 514         printk(banner);
 515         return driver_register(&s3c2410wdt_driver);
 516 }
 517
 518 static void __exit watchdog_exit(void)
 519 {
 520         driver_unregister(&s3c2410wdt_driver);
 521 }
 522
 523 module_init(watchdog_init);
 524 module_exit(watchdog_exit);
 525
 526 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "
 527               "Dimitry Andric <dimitry.andric@tomtom.com>");
 528 MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
 529 MODULE_LICENSE("GPL");
 530 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);