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-2004     BJD     Fixed divide-by-2 in timeout code
  31  *
  32  *      10-Mar-2005     LCVR    Changed S3C2410_VA to S3C24XX_VA
  33 */
  34
  35 #include <linux/module.h>
  36 #include <linux/moduleparam.h>
  37 #include <linux/config.h>
  38 #include <linux/types.h>
  39 #include <linux/timer.h>
  40 #include <linux/miscdevice.h>
  41 #include <linux/watchdog.h>
  42 #include <linux/fs.h>
  43 #include <linux/notifier.h>
  44 #include <linux/reboot.h>
  45 #include <linux/init.h>
  46 #include <linux/device.h>
  47 #include <linux/interrupt.h>
  48
  49 #include <asm/uaccess.h>
  50 #include <asm/io.h>
  51
  52 #include <asm/arch/map.h>
  53 #include <asm/hardware/clock.h>
  54
  55 #undef S3C24XX_VA_WATCHDOG
  56 #define S3C24XX_VA_WATCHDOG (0)
  57
  58 #include <asm/arch/regs-watchdog.h>
  59
  60 #define PFX "s3c2410-wdt: "
  61
  62 #define CONFIG_S3C2410_WATCHDOG_ATBOOT          (0)
  63 #define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME    (15)
  64
  65 #ifdef CONFIG_WATCHDOG_NOWAYOUT
  66 static int nowayout = 1;
  67 #else
  68 static int nowayout = 0;
  69 #endif
  70
  71 static int tmr_margin   = CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME;
  72 static int tmr_atboot   = CONFIG_S3C2410_WATCHDOG_ATBOOT;
  73 static int soft_noboot  = 0;
  74 static int debug        = 0;
  75
  76 module_param(tmr_margin,  int, 0);
  77 module_param(tmr_atboot,  int, 0);
  78 module_param(nowayout,    int, 0);
  79 module_param(soft_noboot, int, 0);
  80 module_param(debug,       int, 0);
  81
  82 MODULE_PARM_DESC(tmr_margin, "Watchdog tmr_margin in seconds. default=" __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME) ")");
  83
  84 MODULE_PARM_DESC(tmr_atboot, "Watchdog is started at boot time if set to 1, default=" __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_ATBOOT));
  85
  86 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
  87
  88 MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)");
  89
  90 MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug, (default 0)");
  91
  92
  93 typedef enum close_state {
  94         CLOSE_STATE_NOT,
  95         CLOSE_STATE_ALLOW=0x4021
  96 } close_state_t;
  97
  98 static DECLARE_MUTEX(open_lock);
  99
 100 static struct resource  *wdt_mem;
 101 static struct resource  *wdt_irq;
 102 static struct clk       *wdt_clock;
 103 static void __iomem     *wdt_base;
 104 static unsigned int      wdt_count;
 105 static close_state_t     allow_close;
 106
 107 /* watchdog control routines */
 108
 109 #define DBG(msg...) do { \
 110         if (debug) \
 111                 printk(KERN_INFO msg); \
 112         } while(0)
 113
 114 /* functions */
 115
 116 static int s3c2410wdt_keepalive(void)
 117 {
 118         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 119         return 0;
 120 }
 121
 122 static int s3c2410wdt_stop(void)
 123 {
 124         unsigned long wtcon;
 125
 126         wtcon = readl(wdt_base + S3C2410_WTCON);
 127         wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
 128         writel(wtcon, wdt_base + S3C2410_WTCON);
 129
 130         return 0;
 131 }
 132
 133 static int s3c2410wdt_start(void)
 134 {
 135         unsigned long wtcon;
 136
 137         s3c2410wdt_stop();
 138
 139         wtcon = readl(wdt_base + S3C2410_WTCON);
 140         wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;
 141
 142         if (soft_noboot) {
 143                 wtcon |= S3C2410_WTCON_INTEN;
 144                 wtcon &= ~S3C2410_WTCON_RSTEN;
 145         } else {
 146                 wtcon &= ~S3C2410_WTCON_INTEN;
 147                 wtcon |= S3C2410_WTCON_RSTEN;
 148         }
 149
 150         DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
 151             __FUNCTION__, wdt_count, wtcon);
 152
 153         writel(wdt_count, wdt_base + S3C2410_WTDAT);
 154         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 155         writel(wtcon, wdt_base + S3C2410_WTCON);
 156
 157         return 0;
 158 }
 159
 160 static int s3c2410wdt_set_heartbeat(int timeout)
 161 {
 162         unsigned int freq = clk_get_rate(wdt_clock);
 163         unsigned int count;
 164         unsigned int divisor = 1;
 165         unsigned long wtcon;
 166
 167         if (timeout < 1)
 168                 return -EINVAL;
 169
 170         freq /= 128;
 171         count = timeout * freq;
 172
 173         DBG("%s: count=%d, timeout=%d, freq=%d\n",
 174             __FUNCTION__, count, timeout, freq);
 175
 176         /* if the count is bigger than the watchdog register,
 177            then work out what we need to do (and if) we can
 178            actually make this value
 179         */
 180
 181         if (count >= 0x10000) {
 182                 for (divisor = 1; divisor <= 0x100; divisor++) {
 183                         if ((count / divisor) < 0x10000)
 184                                 break;
 185                 }
 186
 187                 if ((count / divisor) >= 0x10000) {
 188                         printk(KERN_ERR PFX "timeout %d too big\n", timeout);
 189                         return -EINVAL;
 190                 }
 191         }
 192
 193         tmr_margin = timeout;
 194
 195         DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
 196             __FUNCTION__, timeout, divisor, count, count/divisor);
 197
 198         count /= divisor;
 199         wdt_count = count;
 200
 201         /* update the pre-scaler */
 202         wtcon = readl(wdt_base + S3C2410_WTCON);
 203         wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
 204         wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);
 205
 206         writel(count, wdt_base + S3C2410_WTDAT);
 207         writel(wtcon, wdt_base + S3C2410_WTCON);
 208
 209         return 0;
 210 }
 211
 212 /*
 213  *      /dev/watchdog handling
 214  */
 215
 216 static int s3c2410wdt_open(struct inode *inode, struct file *file)
 217 {
 218         if(down_trylock(&open_lock))
 219                 return -EBUSY;
 220
 221         if (nowayout) {
 222                 __module_get(THIS_MODULE);
 223         } else {
 224                 allow_close = CLOSE_STATE_ALLOW;
 225         }
 226
 227         /* start the timer */
 228         s3c2410wdt_start();
 229         return nonseekable_open(inode, file);
 230 }
 231
 232 static int s3c2410wdt_release(struct inode *inode, struct file *file)
 233 {
 234         /*
 235          *      Shut off the timer.
 236          *      Lock it in if it's a module and we set nowayout
 237          */
 238         if (allow_close == CLOSE_STATE_ALLOW) {
 239                 s3c2410wdt_stop();
 240         } else {
 241                 printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
 242                 s3c2410wdt_keepalive();
 243         }
 244
 245         allow_close = CLOSE_STATE_NOT;
 246         up(&open_lock);
 247         return 0;
 248 }
 249
 250 static ssize_t s3c2410wdt_write(struct file *file, const char __user *data,
 251                                 size_t len, loff_t *ppos)
 252 {
 253         /*
 254          *      Refresh the timer.
 255          */
 256         if(len) {
 257                 if (!nowayout) {
 258                         size_t i;
 259
 260                         /* In case it was set long ago */
 261                         allow_close = CLOSE_STATE_NOT;
 262
 263                         for (i = 0; i != len; i++) {
 264                                 char c;
 265
 266                                 if (get_user(c, data + i))
 267                                         return -EFAULT;
 268                                 if (c == 'V')
 269                                         allow_close = CLOSE_STATE_ALLOW;
 270                         }
 271                 }
 272
 273                 s3c2410wdt_keepalive();
 274         }
 275         return len;
 276 }
 277
 278 #define OPTIONS WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE
 279
 280 static struct watchdog_info s3c2410_wdt_ident = {
 281         .options          =     OPTIONS,
 282         .firmware_version =     0,
 283         .identity         =     "S3C2410 Watchdog",
 284 };
 285
 286
 287 static int s3c2410wdt_ioctl(struct inode *inode, struct file *file,
 288         unsigned int cmd, 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                 default:
 296                         return -ENOIOCTLCMD;
 297
 298                 case WDIOC_GETSUPPORT:
 299                         return copy_to_user(argp, &s3c2410_wdt_ident,
 300                                 sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0;
 301
 302                 case WDIOC_GETSTATUS:
 303                 case WDIOC_GETBOOTSTATUS:
 304                         return put_user(0, p);
 305
 306                 case WDIOC_KEEPALIVE:
 307                         s3c2410wdt_keepalive();
 308                         return 0;
 309
 310                 case WDIOC_SETTIMEOUT:
 311                         if (get_user(new_margin, p))
 312                                 return -EFAULT;
 313
 314                         if (s3c2410wdt_set_heartbeat(new_margin))
 315                                 return -EINVAL;
 316
 317                         s3c2410wdt_keepalive();
 318                         return put_user(tmr_margin, p);
 319
 320                 case WDIOC_GETTIMEOUT:
 321                         return put_user(tmr_margin, p);
 322         }
 323 }
 324
 325 /*
 326  *      Notifier for system down
 327  */
 328
 329 static int s3c2410wdt_notify_sys(struct notifier_block *this, unsigned long code,
 330                               void *unused)
 331 {
 332         if(code==SYS_DOWN || code==SYS_HALT) {
 333                 /* Turn the WDT off */
 334                 s3c2410wdt_stop();
 335         }
 336         return NOTIFY_DONE;
 337 }
 338
 339 /* kernel interface */
 340
 341 static struct file_operations s3c2410wdt_fops = {
 342         .owner          = THIS_MODULE,
 343         .llseek         = no_llseek,
 344         .write          = s3c2410wdt_write,
 345         .ioctl          = s3c2410wdt_ioctl,
 346         .open           = s3c2410wdt_open,
 347         .release        = s3c2410wdt_release,
 348 };
 349
 350 static struct miscdevice s3c2410wdt_miscdev = {
 351         .minor          = WATCHDOG_MINOR,
 352         .name           = "watchdog",
 353         .fops           = &s3c2410wdt_fops,
 354 };
 355
 356 static struct notifier_block s3c2410wdt_notifier = {
 357         .notifier_call  = s3c2410wdt_notify_sys,
 358 };
 359
 360 /* interrupt handler code */
 361
 362 static irqreturn_t s3c2410wdt_irq(int irqno, void *param,
 363                                   struct pt_regs *regs)
 364 {
 365         printk(KERN_INFO PFX "Watchdog timer expired!\n");
 366
 367         s3c2410wdt_keepalive();
 368         return IRQ_HANDLED;
 369 }
 370 /* device interface */
 371
 372 static int s3c2410wdt_probe(struct device *dev)
 373 {
 374         struct platform_device *pdev = to_platform_device(dev);
 375         struct resource *res;
 376         int started = 0;
 377         int ret;
 378         int size;
 379
 380         DBG("%s: probe=%p, device=%p\n", __FUNCTION__, pdev, dev);
 381
 382         /* get the memory region for the watchdog timer */
 383
 384         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 385         if (res == NULL) {
 386                 printk(KERN_INFO PFX "failed to get memory region resouce\n");
 387                 return -ENOENT;
 388         }
 389
 390         size = (res->end-res->start)+1;
 391         wdt_mem = request_mem_region(res->start, size, pdev->name);
 392         if (wdt_mem == NULL) {
 393                 printk(KERN_INFO PFX "failed to get memory region\n");
 394                 return -ENOENT;
 395         }
 396
 397         wdt_base = ioremap(res->start, size);
 398         if (wdt_base == 0) {
 399                 printk(KERN_INFO PFX "failed to ioremap() region\n");
 400                 return -EINVAL;
 401         }
 402
 403         DBG("probe: mapped wdt_base=%p\n", wdt_base);
 404
 405         res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 406         if (res == NULL) {
 407                 printk(KERN_INFO PFX "failed to get irq resource\n");
 408                 return -ENOENT;
 409         }
 410
 411         ret = request_irq(res->start, s3c2410wdt_irq, 0, pdev->name, dev);
 412         if (ret != 0) {
 413                 printk(KERN_INFO PFX "failed to install irq (%d)\n", ret);
 414                 return ret;
 415         }
 416
 417         wdt_clock = clk_get(dev, "watchdog");
 418         if (wdt_clock == NULL) {
 419                 printk(KERN_INFO PFX "failed to find watchdog clock source\n");
 420                 return -ENOENT;
 421         }
 422
 423         clk_use(wdt_clock);
 424         clk_enable(wdt_clock);
 425
 426         /* see if we can actually set the requested timer margin, and if
 427          * not, try the default value */
 428
 429         if (s3c2410wdt_set_heartbeat(tmr_margin)) {
 430                 started = s3c2410wdt_set_heartbeat(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 431
 432                 if (started == 0) {
 433                         printk(KERN_INFO PFX "tmr_margin value out of range, default %d used\n",
 434                                CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 435                 } else {
 436                         printk(KERN_INFO PFX "default timer value is out of range, cannot start\n");
 437                 }
 438         }
 439
 440         ret = register_reboot_notifier(&s3c2410wdt_notifier);
 441         if (ret) {
 442                 printk (KERN_ERR PFX "cannot register reboot notifier (%d)\n",
 443                         ret);
 444                 return ret;
 445         }
 446
 447         ret = misc_register(&s3c2410wdt_miscdev);
 448         if (ret) {
 449                 printk (KERN_ERR PFX "cannot register miscdev on minor=%d (%d)\n",
 450                         WATCHDOG_MINOR, ret);
 451                 unregister_reboot_notifier(&s3c2410wdt_notifier);
 452                 return ret;
 453         }
 454
 455         if (tmr_atboot && started == 0) {
 456                 printk(KERN_INFO PFX "Starting Watchdog Timer\n");
 457                 s3c2410wdt_start();
 458         }
 459
 460         return 0;
 461 }
 462
 463 static int s3c2410wdt_remove(struct device *dev)
 464 {
 465         if (wdt_mem != NULL) {
 466                 release_resource(wdt_mem);
 467                 kfree(wdt_mem);
 468                 wdt_mem = NULL;
 469         }
 470
 471         if (wdt_irq != NULL) {
 472                 free_irq(wdt_irq->start, dev);
 473                 wdt_irq = NULL;
 474         }
 475
 476         if (wdt_clock != NULL) {
 477                 clk_disable(wdt_clock);
 478                 clk_unuse(wdt_clock);
 479                 clk_put(wdt_clock);
 480                 wdt_clock = NULL;
 481         }
 482
 483         misc_deregister(&s3c2410wdt_miscdev);
 484         return 0;
 485 }
 486
 487 static struct device_driver s3c2410wdt_driver = {
 488         .name           = "s3c2410-wdt",
 489         .bus            = &platform_bus_type,
 490         .probe          = s3c2410wdt_probe,
 491         .remove         = s3c2410wdt_remove,
 492 };
 493
 494
 495
 496 static char banner[] __initdata = KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n";
 497
 498 static int __init watchdog_init(void)
 499 {
 500         printk(banner);
 501         return driver_register(&s3c2410wdt_driver);
 502 }
 503
 504 static void __exit watchdog_exit(void)
 505 {
 506         driver_unregister(&s3c2410wdt_driver);
 507         unregister_reboot_notifier(&s3c2410wdt_notifier);
 508 }
 509
 510 module_init(watchdog_init);
 511 module_exit(watchdog_exit);
 512
 513 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
 514 MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
 515 MODULE_LICENSE("GPL");
 516 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);