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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  27
  28 #include <linux/module.h>
  29 #include <linux/moduleparam.h>
  30 #include <linux/types.h>
  31 #include <linux/timer.h>
  32 #include <linux/miscdevice.h> /* for MODULE_ALIAS_MISCDEV */
  33 #include <linux/watchdog.h>
  34 #include <linux/init.h>
  35 #include <linux/platform_device.h>
  36 #include <linux/interrupt.h>
  37 #include <linux/clk.h>
  38 #include <linux/uaccess.h>
  39 #include <linux/io.h>
  40 #include <linux/cpufreq.h>
  41 #include <linux/slab.h>
  42 #include <linux/err.h>
  43 #include <linux/of.h>
  44
  45 #include <mach/map.h>
  46
  47 #undef S3C_VA_WATCHDOG
  48 #define S3C_VA_WATCHDOG (0)
  49
  50 #include <plat/regs-watchdog.h>
  51
  52 #define CONFIG_S3C2410_WATCHDOG_ATBOOT          (0)
  53 #define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME    (15)
  54
  55 static bool nowayout    = WATCHDOG_NOWAYOUT;
  56 static int tmr_margin;
  57 static int tmr_atboot   = CONFIG_S3C2410_WATCHDOG_ATBOOT;
  58 static int soft_noboot;
  59 static int debug;
  60
  61 module_param(tmr_margin,  int, 0);
  62 module_param(tmr_atboot,  int, 0);
  63 module_param(nowayout,   bool, 0);
  64 module_param(soft_noboot, int, 0);
  65 module_param(debug,       int, 0);
  66
  67 MODULE_PARM_DESC(tmr_margin, "Watchdog tmr_margin in seconds. (default="
  68                 __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME) ")");
  69 MODULE_PARM_DESC(tmr_atboot,
  70                 "Watchdog is started at boot time if set to 1, default="
  71                         __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_ATBOOT));
  72 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  73                         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  74 MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, "
  75                         "0 to reboot (default 0)");
  76 MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug (default 0)");
  77
  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 DEFINE_SPINLOCK(wdt_lock);
  85
  86 /* watchdog control routines */
  87
  88 #define DBG(fmt, ...)                                   \
  89 do {                                                    \
  90         if (debug)                                      \
  91                 pr_info(fmt, ##__VA_ARGS__);            \
  92 } while (0)
  93
  94 /* functions */
  95
  96 static int s3c2410wdt_keepalive(struct watchdog_device *wdd)
  97 {
  98         spin_lock(&wdt_lock);
  99         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 100         spin_unlock(&wdt_lock);
 101
 102         return 0;
 103 }
 104
 105 static void __s3c2410wdt_stop(void)
 106 {
 107         unsigned long wtcon;
 108
 109         wtcon = readl(wdt_base + S3C2410_WTCON);
 110         wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
 111         writel(wtcon, wdt_base + S3C2410_WTCON);
 112 }
 113
 114 static int s3c2410wdt_stop(struct watchdog_device *wdd)
 115 {
 116         spin_lock(&wdt_lock);
 117         __s3c2410wdt_stop();
 118         spin_unlock(&wdt_lock);
 119
 120         return 0;
 121 }
 122
 123 static int s3c2410wdt_start(struct watchdog_device *wdd)
 124 {
 125         unsigned long wtcon;
 126
 127         spin_lock(&wdt_lock);
 128
 129         __s3c2410wdt_stop();
 130
 131         wtcon = readl(wdt_base + S3C2410_WTCON);
 132         wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;
 133
 134         if (soft_noboot) {
 135                 wtcon |= S3C2410_WTCON_INTEN;
 136                 wtcon &= ~S3C2410_WTCON_RSTEN;
 137         } else {
 138                 wtcon &= ~S3C2410_WTCON_INTEN;
 139                 wtcon |= S3C2410_WTCON_RSTEN;
 140         }
 141
 142         DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
 143             __func__, wdt_count, wtcon);
 144
 145         writel(wdt_count, wdt_base + S3C2410_WTDAT);
 146         writel(wdt_count, wdt_base + S3C2410_WTCNT);
 147         writel(wtcon, wdt_base + S3C2410_WTCON);
 148         spin_unlock(&wdt_lock);
 149
 150         return 0;
 151 }
 152
 153 static inline int s3c2410wdt_is_running(void)
 154 {
 155         return readl(wdt_base + S3C2410_WTCON) & S3C2410_WTCON_ENABLE;
 156 }
 157
 158 static int s3c2410wdt_set_heartbeat(struct watchdog_device *wdd, unsigned timeout)
 159 {
 160         unsigned long freq = clk_get_rate(wdt_clock);
 161         unsigned int count;
 162         unsigned int divisor = 1;
 163         unsigned long wtcon;
 164
 165         if (timeout < 1)
 166                 return -EINVAL;
 167
 168         freq /= 128;
 169         count = timeout * freq;
 170
 171         DBG("%s: count=%d, timeout=%d, freq=%lu\n",
 172             __func__, count, timeout, freq);
 173
 174         /* if the count is bigger than the watchdog register,
 175            then work out what we need to do (and if) we can
 176            actually make this value
 177         */
 178
 179         if (count >= 0x10000) {
 180                 for (divisor = 1; divisor <= 0x100; divisor++) {
 181                         if ((count / divisor) < 0x10000)
 182                                 break;
 183                 }
 184
 185                 if ((count / divisor) >= 0x10000) {
 186                         dev_err(wdt_dev, "timeout %d too big\n", timeout);
 187                         return -EINVAL;
 188                 }
 189         }
 190
 191         DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
 192             __func__, 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         wdd->timeout = (count * divisor) / freq;
 206
 207         return 0;
 208 }
 209
 210 #define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
 211
 212 static const struct watchdog_info s3c2410_wdt_ident = {
 213         .options          =     OPTIONS,
 214         .firmware_version =     0,
 215         .identity         =     "S3C2410 Watchdog",
 216 };
 217
 218 static struct watchdog_ops s3c2410wdt_ops = {
 219         .owner = THIS_MODULE,
 220         .start = s3c2410wdt_start,
 221         .stop = s3c2410wdt_stop,
 222         .ping = s3c2410wdt_keepalive,
 223         .set_timeout = s3c2410wdt_set_heartbeat,
 224 };
 225
 226 static struct watchdog_device s3c2410_wdd = {
 227         .info = &s3c2410_wdt_ident,
 228         .ops = &s3c2410wdt_ops,
 229         .timeout = CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME,
 230 };
 231
 232 /* interrupt handler code */
 233
 234 static irqreturn_t s3c2410wdt_irq(int irqno, void *param)
 235 {
 236         dev_info(wdt_dev, "watchdog timer expired (irq)\n");
 237
 238         s3c2410wdt_keepalive(&s3c2410_wdd);
 239         return IRQ_HANDLED;
 240 }
 241
 242
 243 #ifdef CONFIG_CPU_FREQ
 244
 245 static int s3c2410wdt_cpufreq_transition(struct notifier_block *nb,
 246                                           unsigned long val, void *data)
 247 {
 248         int ret;
 249
 250         if (!s3c2410wdt_is_running())
 251                 goto done;
 252
 253         if (val == CPUFREQ_PRECHANGE) {
 254                 /* To ensure that over the change we don't cause the
 255                  * watchdog to trigger, we perform an keep-alive if
 256                  * the watchdog is running.
 257                  */
 258
 259                 s3c2410wdt_keepalive(&s3c2410_wdd);
 260         } else if (val == CPUFREQ_POSTCHANGE) {
 261                 s3c2410wdt_stop(&s3c2410_wdd);
 262
 263                 ret = s3c2410wdt_set_heartbeat(&s3c2410_wdd, s3c2410_wdd.timeout);
 264
 265                 if (ret >= 0)
 266                         s3c2410wdt_start(&s3c2410_wdd);
 267                 else
 268                         goto err;
 269         }
 270
 271 done:
 272         return 0;
 273
 274  err:
 275         dev_err(wdt_dev, "cannot set new value for timeout %d\n",
 276                                 s3c2410_wdd.timeout);
 277         return ret;
 278 }
 279
 280 static struct notifier_block s3c2410wdt_cpufreq_transition_nb = {
 281         .notifier_call  = s3c2410wdt_cpufreq_transition,
 282 };
 283
 284 static inline int s3c2410wdt_cpufreq_register(void)
 285 {
 286         return cpufreq_register_notifier(&s3c2410wdt_cpufreq_transition_nb,
 287                                          CPUFREQ_TRANSITION_NOTIFIER);
 288 }
 289
 290 static inline void s3c2410wdt_cpufreq_deregister(void)
 291 {
 292         cpufreq_unregister_notifier(&s3c2410wdt_cpufreq_transition_nb,
 293                                     CPUFREQ_TRANSITION_NOTIFIER);
 294 }
 295
 296 #else
 297 static inline int s3c2410wdt_cpufreq_register(void)
 298 {
 299         return 0;
 300 }
 301
 302 static inline void s3c2410wdt_cpufreq_deregister(void)
 303 {
 304 }
 305 #endif
 306
 307 static int s3c2410wdt_probe(struct platform_device *pdev)
 308 {
 309         struct device *dev;
 310         unsigned int wtcon;
 311         int started = 0;
 312         int ret;
 313
 314         DBG("%s: probe=%p\n", __func__, pdev);
 315
 316         dev = &pdev->dev;
 317         wdt_dev = &pdev->dev;
 318
 319         wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 320         if (wdt_mem == NULL) {
 321                 dev_err(dev, "no memory resource specified\n");
 322                 return -ENOENT;
 323         }
 324
 325         wdt_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 326         if (wdt_irq == NULL) {
 327                 dev_err(dev, "no irq resource specified\n");
 328                 ret = -ENOENT;
 329                 goto err;
 330         }
 331
 332         /* get the memory region for the watchdog timer */
 333         wdt_base = devm_ioremap_resource(dev, wdt_mem);
 334         if (IS_ERR(wdt_base)) {
 335                 ret = PTR_ERR(wdt_base);
 336                 goto err;
 337         }
 338
 339         DBG("probe: mapped wdt_base=%p\n", wdt_base);
 340
 341         wdt_clock = devm_clk_get(dev, "watchdog");
 342         if (IS_ERR(wdt_clock)) {
 343                 dev_err(dev, "failed to find watchdog clock source\n");
 344                 ret = PTR_ERR(wdt_clock);
 345                 goto err;
 346         }
 347
 348         clk_prepare_enable(wdt_clock);
 349
 350         ret = s3c2410wdt_cpufreq_register();
 351         if (ret < 0) {
 352                 pr_err("failed to register cpufreq\n");
 353                 goto err_clk;
 354         }
 355
 356         /* see if we can actually set the requested timer margin, and if
 357          * not, try the default value */
 358
 359         watchdog_init_timeout(&s3c2410_wdd, tmr_margin,  &pdev->dev);
 360         if (s3c2410wdt_set_heartbeat(&s3c2410_wdd, s3c2410_wdd.timeout)) {
 361                 started = s3c2410wdt_set_heartbeat(&s3c2410_wdd,
 362                                         CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 363
 364                 if (started == 0)
 365                         dev_info(dev,
 366                            "tmr_margin value out of range, default %d used\n",
 367                                CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 368                 else
 369                         dev_info(dev, "default timer value is out of range, "
 370                                                         "cannot start\n");
 371         }
 372
 373         ret = devm_request_irq(dev, wdt_irq->start, s3c2410wdt_irq, 0,
 374                                 pdev->name, pdev);
 375         if (ret != 0) {
 376                 dev_err(dev, "failed to install irq (%d)\n", ret);
 377                 goto err_cpufreq;
 378         }
 379
 380         watchdog_set_nowayout(&s3c2410_wdd, nowayout);
 381
 382         ret = watchdog_register_device(&s3c2410_wdd);
 383         if (ret) {
 384                 dev_err(dev, "cannot register watchdog (%d)\n", ret);
 385                 goto err_cpufreq;
 386         }
 387
 388         if (tmr_atboot && started == 0) {
 389                 dev_info(dev, "starting watchdog timer\n");
 390                 s3c2410wdt_start(&s3c2410_wdd);
 391         } else if (!tmr_atboot) {
 392                 /* if we're not enabling the watchdog, then ensure it is
 393                  * disabled if it has been left running from the bootloader
 394                  * or other source */
 395
 396                 s3c2410wdt_stop(&s3c2410_wdd);
 397         }
 398
 399         /* print out a statement of readiness */
 400
 401         wtcon = readl(wdt_base + S3C2410_WTCON);
 402
 403         dev_info(dev, "watchdog %sactive, reset %sabled, irq %sabled\n",
 404                  (wtcon & S3C2410_WTCON_ENABLE) ?  "" : "in",
 405                  (wtcon & S3C2410_WTCON_RSTEN) ? "en" : "dis",
 406                  (wtcon & S3C2410_WTCON_INTEN) ? "en" : "dis");
 407
 408         return 0;
 409
 410  err_cpufreq:
 411         s3c2410wdt_cpufreq_deregister();
 412
 413  err_clk:
 414         clk_disable_unprepare(wdt_clock);
 415         wdt_clock = NULL;
 416
 417  err:
 418         wdt_irq = NULL;
 419         wdt_mem = NULL;
 420         return ret;
 421 }
 422
 423 static int s3c2410wdt_remove(struct platform_device *dev)
 424 {
 425         watchdog_unregister_device(&s3c2410_wdd);
 426
 427         s3c2410wdt_cpufreq_deregister();
 428
 429         clk_disable_unprepare(wdt_clock);
 430         wdt_clock = NULL;
 431
 432         wdt_irq = NULL;
 433         wdt_mem = NULL;
 434         return 0;
 435 }
 436
 437 static void s3c2410wdt_shutdown(struct platform_device *dev)
 438 {
 439         s3c2410wdt_stop(&s3c2410_wdd);
 440 }
 441
 442 #ifdef CONFIG_PM
 443
 444 static unsigned long wtcon_save;
 445 static unsigned long wtdat_save;
 446
 447 static int s3c2410wdt_suspend(struct platform_device *dev, pm_message_t state)
 448 {
 449         /* Save watchdog state, and turn it off. */
 450         wtcon_save = readl(wdt_base + S3C2410_WTCON);
 451         wtdat_save = readl(wdt_base + S3C2410_WTDAT);
 452
 453         /* Note that WTCNT doesn't need to be saved. */
 454         s3c2410wdt_stop(&s3c2410_wdd);
 455
 456         return 0;
 457 }
 458
 459 static int s3c2410wdt_resume(struct platform_device *dev)
 460 {
 461         /* Restore watchdog state. */
 462
 463         writel(wtdat_save, wdt_base + S3C2410_WTDAT);
 464         writel(wtdat_save, wdt_base + S3C2410_WTCNT); /* Reset count */
 465         writel(wtcon_save, wdt_base + S3C2410_WTCON);
 466
 467         pr_info("watchdog %sabled\n",
 468                 (wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
 469
 470         return 0;
 471 }
 472
 473 #else
 474 #define s3c2410wdt_suspend NULL
 475 #define s3c2410wdt_resume  NULL
 476 #endif /* CONFIG_PM */
 477
 478 #ifdef CONFIG_OF
 479 static const struct of_device_id s3c2410_wdt_match[] = {
 480         { .compatible = "samsung,s3c2410-wdt" },
 481         {},
 482 };
 483 MODULE_DEVICE_TABLE(of, s3c2410_wdt_match);
 484 #endif
 485
 486 static struct platform_driver s3c2410wdt_driver = {
 487         .probe          = s3c2410wdt_probe,
 488         .remove         = s3c2410wdt_remove,
 489         .shutdown       = s3c2410wdt_shutdown,
 490         .suspend        = s3c2410wdt_suspend,
 491         .resume         = s3c2410wdt_resume,
 492         .driver         = {
 493                 .owner  = THIS_MODULE,
 494                 .name   = "s3c2410-wdt",
 495                 .of_match_table = of_match_ptr(s3c2410_wdt_match),
 496         },
 497 };
 498
 499 module_platform_driver(s3c2410wdt_driver);
 500
 501 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "
 502               "Dimitry Andric <dimitry.andric@tomtom.com>");
 503 MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
 504 MODULE_LICENSE("GPL");
 505 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 506 MODULE_ALIAS("platform:s3c2410-wdt");