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> /* for MODULE_ALIAS_MISCDEV */
  31 #include <linux/watchdog.h>
  32 #include <linux/init.h>
  33 #include <linux/platform_device.h>
  34 #include <linux/interrupt.h>
  35 #include <linux/clk.h>
  36 #include <linux/uaccess.h>
  37 #include <linux/io.h>
  38 #include <linux/cpufreq.h>
  39 #include <linux/slab.h>
  40 #include <linux/err.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 struct device    *wdt_dev;       /* platform device attached to */
  78 static struct resource  *wdt_mem;
  79 static struct resource  *wdt_irq;
  80 static struct clk       *wdt_clock;
  81 static void __iomem     *wdt_base;
  82 static unsigned int      wdt_count;
  83 static DEFINE_SPINLOCK(wdt_lock);
  84
  85 /* watchdog control routines */
  86
  87 #define DBG(msg...) do { \
  88         if (debug) \
  89                 printk(KERN_INFO msg); \
  90         } while (0)
  91
  92 /* functions */
  93
  94 static int s3c2410wdt_keepalive(struct watchdog_device *wdd)
  95 {
  96         spin_lock(&wdt_lock);
  97         writel(wdt_count, wdt_base + S3C2410_WTCNT);
  98         spin_unlock(&wdt_lock);
  99
 100         return 0;
 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 int s3c2410wdt_stop(struct watchdog_device *wdd)
 113 {
 114         spin_lock(&wdt_lock);
 115         __s3c2410wdt_stop();
 116         spin_unlock(&wdt_lock);
 117
 118         return 0;
 119 }
 120
 121 static int s3c2410wdt_start(struct watchdog_device *wdd)
 122 {
 123         unsigned long wtcon;
 124
 125         spin_lock(&wdt_lock);
 126
 127         __s3c2410wdt_stop();
 128
 129         wtcon = readl(wdt_base + S3C2410_WTCON);
 130         wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;
 131
 132         if (soft_noboot) {
 133                 wtcon |= S3C2410_WTCON_INTEN;
 134                 wtcon &= ~S3C2410_WTCON_RSTEN;
 135         } else {
 136                 wtcon &= ~S3C2410_WTCON_INTEN;
 137                 wtcon |= S3C2410_WTCON_RSTEN;
 138         }
 139
 140         DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
 141             __func__, wdt_count, wtcon);
 142
 143         writel(wdt_count, wdt_base + S3C2410_WTDAT);
 144         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 145         writel(wtcon, wdt_base + S3C2410_WTCON);
 146         spin_unlock(&wdt_lock);
 147
 148         return 0;
 149 }
 150
 151 static inline int s3c2410wdt_is_running(void)
 152 {
 153         return readl(wdt_base + S3C2410_WTCON) & S3C2410_WTCON_ENABLE;
 154 }
 155
 156 static int s3c2410wdt_set_heartbeat(struct watchdog_device *wdd, unsigned timeout)
 157 {
 158         unsigned long 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=%lu\n",
 170             __func__, 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                         dev_err(wdt_dev, "timeout %d too big\n", timeout);
 185                         return -EINVAL;
 186                 }
 187         }
 188
 189         DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
 190             __func__, timeout, divisor, count, count/divisor);
 191
 192         count /= divisor;
 193         wdt_count = count;
 194
 195         /* update the pre-scaler */
 196         wtcon = readl(wdt_base + S3C2410_WTCON);
 197         wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
 198         wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);
 199
 200         writel(count, wdt_base + S3C2410_WTDAT);
 201         writel(wtcon, wdt_base + S3C2410_WTCON);
 202
 203         return 0;
 204 }
 205
 206 #define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
 207
 208 static const struct watchdog_info s3c2410_wdt_ident = {
 209         .options          =     OPTIONS,
 210         .firmware_version =     0,
 211         .identity         =     "S3C2410 Watchdog",
 212 };
 213
 214 static struct watchdog_ops s3c2410wdt_ops = {
 215         .owner = THIS_MODULE,
 216         .start = s3c2410wdt_start,
 217         .stop = s3c2410wdt_stop,
 218         .ping = s3c2410wdt_keepalive,
 219         .set_timeout = s3c2410wdt_set_heartbeat,
 220 };
 221
 222 static struct watchdog_device s3c2410_wdd = {
 223         .info = &s3c2410_wdt_ident,
 224         .ops = &s3c2410wdt_ops,
 225 };
 226
 227 /* interrupt handler code */
 228
 229 static irqreturn_t s3c2410wdt_irq(int irqno, void *param)
 230 {
 231         dev_info(wdt_dev, "watchdog timer expired (irq)\n");
 232
 233         s3c2410wdt_keepalive(&s3c2410_wdd);
 234         return IRQ_HANDLED;
 235 }
 236
 237
 238 #ifdef CONFIG_CPU_FREQ
 239
 240 static int s3c2410wdt_cpufreq_transition(struct notifier_block *nb,
 241                                           unsigned long val, void *data)
 242 {
 243         int ret;
 244
 245         if (!s3c2410wdt_is_running())
 246                 goto done;
 247
 248         if (val == CPUFREQ_PRECHANGE) {
 249                 /* To ensure that over the change we don't cause the
 250                  * watchdog to trigger, we perform an keep-alive if
 251                  * the watchdog is running.
 252                  */
 253
 254                 s3c2410wdt_keepalive(&s3c2410_wdd);
 255         } else if (val == CPUFREQ_POSTCHANGE) {
 256                 s3c2410wdt_stop(&s3c2410_wdd);
 257
 258                 ret = s3c2410wdt_set_heartbeat(&s3c2410_wdd, s3c2410_wdd.timeout);
 259
 260                 if (ret >= 0)
 261                         s3c2410wdt_start(&s3c2410_wdd);
 262                 else
 263                         goto err;
 264         }
 265
 266 done:
 267         return 0;
 268
 269  err:
 270         dev_err(wdt_dev, "cannot set new value for timeout %d\n",
 271                                 s3c2410_wdd.timeout);
 272         return ret;
 273 }
 274
 275 static struct notifier_block s3c2410wdt_cpufreq_transition_nb = {
 276         .notifier_call  = s3c2410wdt_cpufreq_transition,
 277 };
 278
 279 static inline int s3c2410wdt_cpufreq_register(void)
 280 {
 281         return cpufreq_register_notifier(&s3c2410wdt_cpufreq_transition_nb,
 282                                          CPUFREQ_TRANSITION_NOTIFIER);
 283 }
 284
 285 static inline void s3c2410wdt_cpufreq_deregister(void)
 286 {
 287         cpufreq_unregister_notifier(&s3c2410wdt_cpufreq_transition_nb,
 288                                     CPUFREQ_TRANSITION_NOTIFIER);
 289 }
 290
 291 #else
 292 static inline int s3c2410wdt_cpufreq_register(void)
 293 {
 294         return 0;
 295 }
 296
 297 static inline void s3c2410wdt_cpufreq_deregister(void)
 298 {
 299 }
 300 #endif
 301
 302 static int __devinit s3c2410wdt_probe(struct platform_device *pdev)
 303 {
 304         struct device *dev;
 305         unsigned int wtcon;
 306         int started = 0;
 307         int ret;
 308         int size;
 309
 310         DBG("%s: probe=%p\n", __func__, pdev);
 311
 312         dev = &pdev->dev;
 313         wdt_dev = &pdev->dev;
 314
 315         /* get the memory region for the watchdog timer */
 316
 317         wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 318         if (wdt_mem == NULL) {
 319                 dev_err(dev, "no memory resource specified\n");
 320                 return -ENOENT;
 321         }
 322
 323         size = resource_size(wdt_mem);
 324         if (!request_mem_region(wdt_mem->start, size, pdev->name)) {
 325                 dev_err(dev, "failed to get memory region\n");
 326                 return -EBUSY;
 327         }
 328
 329         wdt_base = ioremap(wdt_mem->start, size);
 330         if (wdt_base == NULL) {
 331                 dev_err(dev, "failed to ioremap() region\n");
 332                 ret = -EINVAL;
 333                 goto err_req;
 334         }
 335
 336         DBG("probe: mapped wdt_base=%p\n", wdt_base);
 337
 338         wdt_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 339         if (wdt_irq == NULL) {
 340                 dev_err(dev, "no irq resource specified\n");
 341                 ret = -ENOENT;
 342                 goto err_map;
 343         }
 344
 345         ret = request_irq(wdt_irq->start, s3c2410wdt_irq, 0, pdev->name, pdev);
 346         if (ret != 0) {
 347                 dev_err(dev, "failed to install irq (%d)\n", ret);
 348                 goto err_map;
 349         }
 350
 351         wdt_clock = clk_get(&pdev->dev, "watchdog");
 352         if (IS_ERR(wdt_clock)) {
 353                 dev_err(dev, "failed to find watchdog clock source\n");
 354                 ret = PTR_ERR(wdt_clock);
 355                 goto err_irq;
 356         }
 357
 358         clk_enable(wdt_clock);
 359
 360         if (s3c2410wdt_cpufreq_register() < 0) {
 361                 printk(KERN_ERR PFX "failed to register cpufreq\n");
 362                 goto err_clk;
 363         }
 364
 365         /* see if we can actually set the requested timer margin, and if
 366          * not, try the default value */
 367
 368         if (s3c2410wdt_set_heartbeat(&s3c2410_wdd, tmr_margin)) {
 369                 started = s3c2410wdt_set_heartbeat(&s3c2410_wdd,
 370                                         CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 371
 372                 if (started == 0)
 373                         dev_info(dev,
 374                            "tmr_margin value out of range, default %d used\n",
 375                                CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 376                 else
 377                         dev_info(dev, "default timer value is out of range, "
 378                                                         "cannot start\n");
 379         }
 380
 381         ret = watchdog_register_device(&s3c2410_wdd);
 382         if (ret) {
 383                 dev_err(dev, "cannot register watchdog (%d)\n", ret);
 384                 goto err_cpufreq;
 385         }
 386
 387         if (tmr_atboot && started == 0) {
 388                 dev_info(dev, "starting watchdog timer\n");
 389                 s3c2410wdt_start(&s3c2410_wdd);
 390         } else if (!tmr_atboot) {
 391                 /* if we're not enabling the watchdog, then ensure it is
 392                  * disabled if it has been left running from the bootloader
 393                  * or other source */
 394
 395                 s3c2410wdt_stop(&s3c2410_wdd);
 396         }
 397
 398         /* print out a statement of readiness */
 399
 400         wtcon = readl(wdt_base + S3C2410_WTCON);
 401
 402         dev_info(dev, "watchdog %sactive, reset %sabled, irq %sabled\n",
 403                  (wtcon & S3C2410_WTCON_ENABLE) ?  "" : "in",
 404                  (wtcon & S3C2410_WTCON_RSTEN) ? "en" : "dis",
 405                  (wtcon & S3C2410_WTCON_INTEN) ? "en" : "dis");
 406
 407         return 0;
 408
 409  err_cpufreq:
 410         s3c2410wdt_cpufreq_deregister();
 411
 412  err_clk:
 413         clk_disable(wdt_clock);
 414         clk_put(wdt_clock);
 415
 416  err_irq:
 417         free_irq(wdt_irq->start, pdev);
 418
 419  err_map:
 420         iounmap(wdt_base);
 421
 422  err_req:
 423         release_mem_region(wdt_mem->start, size);
 424         wdt_mem = NULL;
 425
 426         return ret;
 427 }
 428
 429 static int __devexit s3c2410wdt_remove(struct platform_device *dev)
 430 {
 431         watchdog_unregister_device(&s3c2410_wdd);
 432
 433         s3c2410wdt_cpufreq_deregister();
 434
 435         clk_disable(wdt_clock);
 436         clk_put(wdt_clock);
 437         wdt_clock = NULL;
 438
 439         free_irq(wdt_irq->start, dev);
 440         wdt_irq = NULL;
 441
 442         iounmap(wdt_base);
 443
 444         release_mem_region(wdt_mem->start, resource_size(wdt_mem));
 445         wdt_mem = NULL;
 446         return 0;
 447 }
 448
 449 static void s3c2410wdt_shutdown(struct platform_device *dev)
 450 {
 451         s3c2410wdt_stop(&s3c2410_wdd);
 452 }
 453
 454 #ifdef CONFIG_PM
 455
 456 static unsigned long wtcon_save;
 457 static unsigned long wtdat_save;
 458
 459 static int s3c2410wdt_suspend(struct platform_device *dev, pm_message_t state)
 460 {
 461         /* Save watchdog state, and turn it off. */
 462         wtcon_save = readl(wdt_base + S3C2410_WTCON);
 463         wtdat_save = readl(wdt_base + S3C2410_WTDAT);
 464
 465         /* Note that WTCNT doesn't need to be saved. */
 466         s3c2410wdt_stop(&s3c2410_wdd);
 467
 468         return 0;
 469 }
 470
 471 static int s3c2410wdt_resume(struct platform_device *dev)
 472 {
 473         /* Restore watchdog state. */
 474
 475         writel(wtdat_save, wdt_base + S3C2410_WTDAT);
 476         writel(wtdat_save, wdt_base + S3C2410_WTCNT); /* Reset count */
 477         writel(wtcon_save, wdt_base + S3C2410_WTCON);
 478
 479         printk(KERN_INFO PFX "watchdog %sabled\n",
 480                (wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
 481
 482         return 0;
 483 }
 484
 485 #else
 486 #define s3c2410wdt_suspend NULL
 487 #define s3c2410wdt_resume  NULL
 488 #endif /* CONFIG_PM */
 489
 490 #ifdef CONFIG_OF
 491 static const struct of_device_id s3c2410_wdt_match[] = {
 492         { .compatible = "samsung,s3c2410-wdt" },
 493         {},
 494 };
 495 MODULE_DEVICE_TABLE(of, s3c2410_wdt_match);
 496 #else
 497 #define s3c2410_wdt_match NULL
 498 #endif
 499
 500 static struct platform_driver s3c2410wdt_driver = {
 501         .probe          = s3c2410wdt_probe,
 502         .remove         = __devexit_p(s3c2410wdt_remove),
 503         .shutdown       = s3c2410wdt_shutdown,
 504         .suspend        = s3c2410wdt_suspend,
 505         .resume         = s3c2410wdt_resume,
 506         .driver         = {
 507                 .owner  = THIS_MODULE,
 508                 .name   = "s3c2410-wdt",
 509                 .of_match_table = s3c2410_wdt_match,
 510         },
 511 };
 512
 513
 514 static char banner[] __initdata =
 515         KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n";
 516
 517 static int __init watchdog_init(void)
 518 {
 519         printk(banner);
 520         return platform_driver_register(&s3c2410wdt_driver);
 521 }
 522
 523 static void __exit watchdog_exit(void)
 524 {
 525         platform_driver_unregister(&s3c2410wdt_driver);
 526 }
 527
 528 module_init(watchdog_init);
 529 module_exit(watchdog_exit);
 530
 531 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "
 532               "Dimitry Andric <dimitry.andric@tomtom.com>");
 533 MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
 534 MODULE_LICENSE("GPL");
 535 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 536 MODULE_ALIAS("platform:s3c2410-wdt");