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 #define S3C2410_WTCON           0x00
  46 #define S3C2410_WTDAT           0x04
  47 #define S3C2410_WTCNT           0x08
  48
  49 #define S3C2410_WTCON_RSTEN     (1 << 0)
  50 #define S3C2410_WTCON_INTEN     (1 << 2)
  51 #define S3C2410_WTCON_ENABLE    (1 << 5)
  52
  53 #define S3C2410_WTCON_DIV16     (0 << 3)
  54 #define S3C2410_WTCON_DIV32     (1 << 3)
  55 #define S3C2410_WTCON_DIV64     (2 << 3)
  56 #define S3C2410_WTCON_DIV128    (3 << 3)
  57
  58 #define S3C2410_WTCON_PRESCALE(x)       ((x) << 8)
  59 #define S3C2410_WTCON_PRESCALE_MASK     (0xff << 8)
  60
  61 #define CONFIG_S3C2410_WATCHDOG_ATBOOT          (0)
  62 #define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME    (15)
  63
  64 static bool nowayout    = WATCHDOG_NOWAYOUT;
  65 static int tmr_margin;
  66 static int tmr_atboot   = CONFIG_S3C2410_WATCHDOG_ATBOOT;
  67 static int soft_noboot;
  68 static int debug;
  69
  70 module_param(tmr_margin,  int, 0);
  71 module_param(tmr_atboot,  int, 0);
  72 module_param(nowayout,   bool, 0);
  73 module_param(soft_noboot, int, 0);
  74 module_param(debug,       int, 0);
  75
  76 MODULE_PARM_DESC(tmr_margin, "Watchdog tmr_margin in seconds. (default="
  77                 __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME) ")");
  78 MODULE_PARM_DESC(tmr_atboot,
  79                 "Watchdog is started at boot time if set to 1, default="
  80                         __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_ATBOOT));
  81 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  82                         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  83 MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, "
  84                         "0 to reboot (default 0)");
  85 MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug (default 0)");
  86
  87 struct s3c2410_wdt {
  88         struct device           *dev;
  89         struct clk              *clock;
  90         void __iomem            *reg_base;
  91         unsigned int            count;
  92         spinlock_t              lock;
  93         unsigned long           wtcon_save;
  94         unsigned long           wtdat_save;
  95         struct watchdog_device  wdt_device;
  96         struct notifier_block   freq_transition;
  97 };
  98
  99 /* watchdog control routines */
 100
 101 #define DBG(fmt, ...)                                   \
 102 do {                                                    \
 103         if (debug)                                      \
 104                 pr_info(fmt, ##__VA_ARGS__);            \
 105 } while (0)
 106
 107 /* functions */
 108
 109 static inline struct s3c2410_wdt *freq_to_wdt(struct notifier_block *nb)
 110 {
 111         return container_of(nb, struct s3c2410_wdt, freq_transition);
 112 }
 113
 114 static int s3c2410wdt_keepalive(struct watchdog_device *wdd)
 115 {
 116         struct s3c2410_wdt *wdt = watchdog_get_drvdata(wdd);
 117
 118         spin_lock(&wdt->lock);
 119         writel(wdt->count, wdt->reg_base + S3C2410_WTCNT);
 120         spin_unlock(&wdt->lock);
 121
 122         return 0;
 123 }
 124
 125 static void __s3c2410wdt_stop(struct s3c2410_wdt *wdt)
 126 {
 127         unsigned long wtcon;
 128
 129         wtcon = readl(wdt->reg_base + S3C2410_WTCON);
 130         wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
 131         writel(wtcon, wdt->reg_base + S3C2410_WTCON);
 132 }
 133
 134 static int s3c2410wdt_stop(struct watchdog_device *wdd)
 135 {
 136         struct s3c2410_wdt *wdt = watchdog_get_drvdata(wdd);
 137
 138         spin_lock(&wdt->lock);
 139         __s3c2410wdt_stop(wdt);
 140         spin_unlock(&wdt->lock);
 141
 142         return 0;
 143 }
 144
 145 static int s3c2410wdt_start(struct watchdog_device *wdd)
 146 {
 147         unsigned long wtcon;
 148         struct s3c2410_wdt *wdt = watchdog_get_drvdata(wdd);
 149
 150         spin_lock(&wdt->lock);
 151
 152         __s3c2410wdt_stop(wdt);
 153
 154         wtcon = readl(wdt->reg_base + S3C2410_WTCON);
 155         wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;
 156
 157         if (soft_noboot) {
 158                 wtcon |= S3C2410_WTCON_INTEN;
 159                 wtcon &= ~S3C2410_WTCON_RSTEN;
 160         } else {
 161                 wtcon &= ~S3C2410_WTCON_INTEN;
 162                 wtcon |= S3C2410_WTCON_RSTEN;
 163         }
 164
 165         DBG("%s: count=0x%08x, wtcon=%08lx\n",
 166             __func__, wdt->count, wtcon);
 167
 168         writel(wdt->count, wdt->reg_base + S3C2410_WTDAT);
 169         writel(wdt->count, wdt->reg_base + S3C2410_WTCNT);
 170         writel(wtcon, wdt->reg_base + S3C2410_WTCON);
 171         spin_unlock(&wdt->lock);
 172
 173         return 0;
 174 }
 175
 176 static inline int s3c2410wdt_is_running(struct s3c2410_wdt *wdt)
 177 {
 178         return readl(wdt->reg_base + S3C2410_WTCON) & S3C2410_WTCON_ENABLE;
 179 }
 180
 181 static int s3c2410wdt_set_heartbeat(struct watchdog_device *wdd, unsigned timeout)
 182 {
 183         struct s3c2410_wdt *wdt = watchdog_get_drvdata(wdd);
 184         unsigned long freq = clk_get_rate(wdt->clock);
 185         unsigned int count;
 186         unsigned int divisor = 1;
 187         unsigned long wtcon;
 188
 189         if (timeout < 1)
 190                 return -EINVAL;
 191
 192         freq /= 128;
 193         count = timeout * freq;
 194
 195         DBG("%s: count=%d, timeout=%d, freq=%lu\n",
 196             __func__, count, timeout, freq);
 197
 198         /* if the count is bigger than the watchdog register,
 199            then work out what we need to do (and if) we can
 200            actually make this value
 201         */
 202
 203         if (count >= 0x10000) {
 204                 for (divisor = 1; divisor <= 0x100; divisor++) {
 205                         if ((count / divisor) < 0x10000)
 206                                 break;
 207                 }
 208
 209                 if ((count / divisor) >= 0x10000) {
 210                         dev_err(wdt->dev, "timeout %d too big\n", timeout);
 211                         return -EINVAL;
 212                 }
 213         }
 214
 215         DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
 216             __func__, timeout, divisor, count, count/divisor);
 217
 218         count /= divisor;
 219         wdt->count = count;
 220
 221         /* update the pre-scaler */
 222         wtcon = readl(wdt->reg_base + S3C2410_WTCON);
 223         wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
 224         wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);
 225
 226         writel(count, wdt->reg_base + S3C2410_WTDAT);
 227         writel(wtcon, wdt->reg_base + S3C2410_WTCON);
 228
 229         wdd->timeout = (count * divisor) / freq;
 230
 231         return 0;
 232 }
 233
 234 #define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
 235
 236 static const struct watchdog_info s3c2410_wdt_ident = {
 237         .options          =     OPTIONS,
 238         .firmware_version =     0,
 239         .identity         =     "S3C2410 Watchdog",
 240 };
 241
 242 static struct watchdog_ops s3c2410wdt_ops = {
 243         .owner = THIS_MODULE,
 244         .start = s3c2410wdt_start,
 245         .stop = s3c2410wdt_stop,
 246         .ping = s3c2410wdt_keepalive,
 247         .set_timeout = s3c2410wdt_set_heartbeat,
 248 };
 249
 250 static struct watchdog_device s3c2410_wdd = {
 251         .info = &s3c2410_wdt_ident,
 252         .ops = &s3c2410wdt_ops,
 253         .timeout = CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME,
 254 };
 255
 256 /* interrupt handler code */
 257
 258 static irqreturn_t s3c2410wdt_irq(int irqno, void *param)
 259 {
 260         struct s3c2410_wdt *wdt = platform_get_drvdata(param);
 261
 262         dev_info(wdt->dev, "watchdog timer expired (irq)\n");
 263
 264         s3c2410wdt_keepalive(&wdt->wdt_device);
 265         return IRQ_HANDLED;
 266 }
 267
 268 #ifdef CONFIG_CPU_FREQ
 269
 270 static int s3c2410wdt_cpufreq_transition(struct notifier_block *nb,
 271                                           unsigned long val, void *data)
 272 {
 273         int ret;
 274         struct s3c2410_wdt *wdt = freq_to_wdt(nb);
 275
 276         if (!s3c2410wdt_is_running(wdt))
 277                 goto done;
 278
 279         if (val == CPUFREQ_PRECHANGE) {
 280                 /* To ensure that over the change we don't cause the
 281                  * watchdog to trigger, we perform an keep-alive if
 282                  * the watchdog is running.
 283                  */
 284
 285                 s3c2410wdt_keepalive(&wdt->wdt_device);
 286         } else if (val == CPUFREQ_POSTCHANGE) {
 287                 s3c2410wdt_stop(&wdt->wdt_device);
 288
 289                 ret = s3c2410wdt_set_heartbeat(&wdt->wdt_device,
 290                                                 wdt->wdt_device.timeout);
 291
 292                 if (ret >= 0)
 293                         s3c2410wdt_start(&wdt->wdt_device);
 294                 else
 295                         goto err;
 296         }
 297
 298 done:
 299         return 0;
 300
 301  err:
 302         dev_err(wdt->dev, "cannot set new value for timeout %d\n",
 303                                 wdt->wdt_device.timeout);
 304         return ret;
 305 }
 306
 307 static inline int s3c2410wdt_cpufreq_register(struct s3c2410_wdt *wdt)
 308 {
 309         wdt->freq_transition.notifier_call = s3c2410wdt_cpufreq_transition;
 310
 311         return cpufreq_register_notifier(&wdt->freq_transition,
 312                                          CPUFREQ_TRANSITION_NOTIFIER);
 313 }
 314
 315 static inline void s3c2410wdt_cpufreq_deregister(struct s3c2410_wdt *wdt)
 316 {
 317         wdt->freq_transition.notifier_call = s3c2410wdt_cpufreq_transition;
 318
 319         cpufreq_unregister_notifier(&wdt->freq_transition,
 320                                     CPUFREQ_TRANSITION_NOTIFIER);
 321 }
 322
 323 #else
 324
 325 static inline int s3c2410wdt_cpufreq_register(struct s3c2410_wdt *wdt)
 326 {
 327         return 0;
 328 }
 329
 330 static inline void s3c2410wdt_cpufreq_deregister(struct s3c2410_wdt *wdt)
 331 {
 332 }
 333 #endif
 334
 335 static int s3c2410wdt_probe(struct platform_device *pdev)
 336 {
 337         struct device *dev;
 338         struct s3c2410_wdt *wdt;
 339         struct resource *wdt_mem;
 340         struct resource *wdt_irq;
 341         unsigned int wtcon;
 342         int started = 0;
 343         int ret;
 344
 345         DBG("%s: probe=%p\n", __func__, pdev);
 346
 347         dev = &pdev->dev;
 348
 349         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 350         if (!wdt)
 351                 return -ENOMEM;
 352
 353         wdt->dev = &pdev->dev;
 354         spin_lock_init(&wdt->lock);
 355         wdt->wdt_device = s3c2410_wdd;
 356         wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 357         if (wdt_mem == NULL) {
 358                 dev_err(dev, "no memory resource specified\n");
 359                 return -ENOENT;
 360         }
 361
 362         wdt_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 363         if (wdt_irq == NULL) {
 364                 dev_err(dev, "no irq resource specified\n");
 365                 ret = -ENOENT;
 366                 goto err;
 367         }
 368
 369         /* get the memory region for the watchdog timer */
 370         wdt->reg_base = devm_ioremap_resource(dev, wdt_mem);
 371         if (IS_ERR(wdt->reg_base)) {
 372                 ret = PTR_ERR(wdt->reg_base);
 373                 goto err;
 374         }
 375
 376         DBG("probe: mapped reg_base=%p\n", wdt->reg_base);
 377
 378         wdt->clock = devm_clk_get(dev, "watchdog");
 379         if (IS_ERR(wdt->clock)) {
 380                 dev_err(dev, "failed to find watchdog clock source\n");
 381                 ret = PTR_ERR(wdt->clock);
 382                 goto err;
 383         }
 384
 385         clk_prepare_enable(wdt->clock);
 386
 387         ret = s3c2410wdt_cpufreq_register(wdt);
 388         if (ret < 0) {
 389                 dev_err(dev, "failed to register cpufreq\n");
 390                 goto err_clk;
 391         }
 392
 393         watchdog_set_drvdata(&wdt->wdt_device, wdt);
 394
 395         /* see if we can actually set the requested timer margin, and if
 396          * not, try the default value */
 397
 398         watchdog_init_timeout(&wdt->wdt_device, tmr_margin, &pdev->dev);
 399         ret = s3c2410wdt_set_heartbeat(&wdt->wdt_device,
 400                                         wdt->wdt_device.timeout);
 401         if (ret) {
 402                 started = s3c2410wdt_set_heartbeat(&wdt->wdt_device,
 403                                         CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 404
 405                 if (started == 0)
 406                         dev_info(dev,
 407                            "tmr_margin value out of range, default %d used\n",
 408                                CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
 409                 else
 410                         dev_info(dev, "default timer value is out of range, "
 411                                                         "cannot start\n");
 412         }
 413
 414         ret = devm_request_irq(dev, wdt_irq->start, s3c2410wdt_irq, 0,
 415                                 pdev->name, pdev);
 416         if (ret != 0) {
 417                 dev_err(dev, "failed to install irq (%d)\n", ret);
 418                 goto err_cpufreq;
 419         }
 420
 421         watchdog_set_nowayout(&wdt->wdt_device, nowayout);
 422
 423         ret = watchdog_register_device(&wdt->wdt_device);
 424         if (ret) {
 425                 dev_err(dev, "cannot register watchdog (%d)\n", ret);
 426                 goto err_cpufreq;
 427         }
 428
 429         if (tmr_atboot && started == 0) {
 430                 dev_info(dev, "starting watchdog timer\n");
 431                 s3c2410wdt_start(&wdt->wdt_device);
 432         } else if (!tmr_atboot) {
 433                 /* if we're not enabling the watchdog, then ensure it is
 434                  * disabled if it has been left running from the bootloader
 435                  * or other source */
 436
 437                 s3c2410wdt_stop(&wdt->wdt_device);
 438         }
 439
 440         platform_set_drvdata(pdev, wdt);
 441
 442         /* print out a statement of readiness */
 443
 444         wtcon = readl(wdt->reg_base + S3C2410_WTCON);
 445
 446         dev_info(dev, "watchdog %sactive, reset %sabled, irq %sabled\n",
 447                  (wtcon & S3C2410_WTCON_ENABLE) ?  "" : "in",
 448                  (wtcon & S3C2410_WTCON_RSTEN) ? "en" : "dis",
 449                  (wtcon & S3C2410_WTCON_INTEN) ? "en" : "dis");
 450
 451         return 0;
 452
 453  err_cpufreq:
 454         s3c2410wdt_cpufreq_deregister(wdt);
 455
 456  err_clk:
 457         clk_disable_unprepare(wdt->clock);
 458         wdt->clock = NULL;
 459
 460  err:
 461         return ret;
 462 }
 463
 464 static int s3c2410wdt_remove(struct platform_device *dev)
 465 {
 466         struct s3c2410_wdt *wdt = platform_get_drvdata(dev);
 467
 468         watchdog_unregister_device(&wdt->wdt_device);
 469
 470         s3c2410wdt_cpufreq_deregister(wdt);
 471
 472         clk_disable_unprepare(wdt->clock);
 473         wdt->clock = NULL;
 474
 475         return 0;
 476 }
 477
 478 static void s3c2410wdt_shutdown(struct platform_device *dev)
 479 {
 480         struct s3c2410_wdt *wdt = platform_get_drvdata(dev);
 481
 482         s3c2410wdt_stop(&wdt->wdt_device);
 483 }
 484
 485 #ifdef CONFIG_PM_SLEEP
 486
 487 static int s3c2410wdt_suspend(struct device *dev)
 488 {
 489         struct s3c2410_wdt *wdt = dev_get_drvdata(dev);
 490
 491         /* Save watchdog state, and turn it off. */
 492         wdt->wtcon_save = readl(wdt->reg_base + S3C2410_WTCON);
 493         wdt->wtdat_save = readl(wdt->reg_base + S3C2410_WTDAT);
 494
 495         /* Note that WTCNT doesn't need to be saved. */
 496         s3c2410wdt_stop(&wdt->wdt_device);
 497
 498         return 0;
 499 }
 500
 501 static int s3c2410wdt_resume(struct device *dev)
 502 {
 503         struct s3c2410_wdt *wdt = dev_get_drvdata(dev);
 504
 505         /* Restore watchdog state. */
 506         writel(wdt->wtdat_save, wdt->reg_base + S3C2410_WTDAT);
 507         writel(wdt->wtdat_save, wdt->reg_base + S3C2410_WTCNT);/* Reset count */
 508         writel(wdt->wtcon_save, wdt->reg_base + S3C2410_WTCON);
 509
 510         dev_info(dev, "watchdog %sabled\n",
 511                 (wdt->wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
 512
 513         return 0;
 514 }
 515 #endif
 516
 517 static SIMPLE_DEV_PM_OPS(s3c2410wdt_pm_ops, s3c2410wdt_suspend,
 518                         s3c2410wdt_resume);
 519
 520 #ifdef CONFIG_OF
 521 static const struct of_device_id s3c2410_wdt_match[] = {
 522         { .compatible = "samsung,s3c2410-wdt" },
 523         {},
 524 };
 525 MODULE_DEVICE_TABLE(of, s3c2410_wdt_match);
 526 #endif
 527
 528 static struct platform_driver s3c2410wdt_driver = {
 529         .probe          = s3c2410wdt_probe,
 530         .remove         = s3c2410wdt_remove,
 531         .shutdown       = s3c2410wdt_shutdown,
 532         .driver         = {
 533                 .owner  = THIS_MODULE,
 534                 .name   = "s3c2410-wdt",
 535                 .pm     = &s3c2410wdt_pm_ops,
 536                 .of_match_table = of_match_ptr(s3c2410_wdt_match),
 537         },
 538 };
 539
 540 module_platform_driver(s3c2410wdt_driver);
 541
 542 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "
 543               "Dimitry Andric <dimitry.andric@tomtom.com>");
 544 MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
 545 MODULE_LICENSE("GPL");
 546 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 547 MODULE_ALIAS("platform:s3c2410-wdt");