drivers/watchdog/kempld_wdt.c

   1 /*
   2  * Kontron PLD watchdog driver
   3  *
   4  * Copyright (c) 2010-2013 Kontron Europe GmbH
   5  * Author: Michael Brunner <michael.brunner@kontron.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License 2 as published
   9  * by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * Note: From the PLD watchdog point of view timeout and pretimeout are
  17  *       defined differently than in the kernel.
  18  *       First the pretimeout stage runs out before the timeout stage gets
  19  *       active.
  20  *
  21  * Kernel/API:                     P-----| pretimeout
  22  *               |-----------------------T timeout
  23  * Watchdog:     |-----------------P       pretimeout_stage
  24  *                                 |-----T timeout_stage
  25  */
  26
  27 #include <linux/module.h>
  28 #include <linux/moduleparam.h>
  29 #include <linux/uaccess.h>
  30 #include <linux/watchdog.h>
  31 #include <linux/platform_device.h>
  32 #include <linux/mfd/kempld.h>
  33
  34 #define KEMPLD_WDT_STAGE_TIMEOUT(x)     (0x1b + (x) * 4)
  35 #define KEMPLD_WDT_STAGE_CFG(x)         (0x18 + (x))
  36 #define STAGE_CFG_GET_PRESCALER(x)      (((x) & 0x30) >> 4)
  37 #define STAGE_CFG_SET_PRESCALER(x)      (((x) & 0x3) << 4)
  38 #define STAGE_CFG_PRESCALER_MASK        0x30
  39 #define STAGE_CFG_ACTION_MASK           0x7
  40 #define STAGE_CFG_ASSERT                (1 << 3)
  41
  42 #define KEMPLD_WDT_MAX_STAGES           2
  43 #define KEMPLD_WDT_KICK                 0x16
  44 #define KEMPLD_WDT_CFG                  0x17
  45 #define KEMPLD_WDT_CFG_ENABLE           0x10
  46 #define KEMPLD_WDT_CFG_ENABLE_LOCK      0x8
  47 #define KEMPLD_WDT_CFG_GLOBAL_LOCK      0x80
  48
  49 enum {
  50         ACTION_NONE = 0,
  51         ACTION_RESET,
  52         ACTION_NMI,
  53         ACTION_SMI,
  54         ACTION_SCI,
  55         ACTION_DELAY,
  56 };
  57
  58 enum {
  59         STAGE_TIMEOUT = 0,
  60         STAGE_PRETIMEOUT,
  61 };
  62
  63 enum {
  64         PRESCALER_21 = 0,
  65         PRESCALER_17,
  66         PRESCALER_12,
  67 };
  68
  69 static const u32 kempld_prescaler[] = {
  70         [PRESCALER_21] = (1 << 21) - 1,
  71         [PRESCALER_17] = (1 << 17) - 1,
  72         [PRESCALER_12] = (1 << 12) - 1,
  73         0,
  74 };
  75
  76 struct kempld_wdt_stage {
  77         unsigned int    id;
  78         u32             mask;
  79 };
  80
  81 struct kempld_wdt_data {
  82         struct kempld_device_data       *pld;
  83         struct watchdog_device          wdd;
  84         unsigned int                    pretimeout;
  85         struct kempld_wdt_stage         stage[KEMPLD_WDT_MAX_STAGES];
  86 #ifdef CONFIG_PM
  87         u8                              pm_status_store;
  88 #endif
  89 };
  90
  91 #define DEFAULT_TIMEOUT         30 /* seconds */
  92 #define DEFAULT_PRETIMEOUT      0
  93
  94 static unsigned int timeout = DEFAULT_TIMEOUT;
  95 module_param(timeout, uint, 0);
  96 MODULE_PARM_DESC(timeout,
  97         "Watchdog timeout in seconds. (>=0, default="
  98         __MODULE_STRING(DEFAULT_TIMEOUT) ")");
  99
 100 static unsigned int pretimeout = DEFAULT_PRETIMEOUT;
 101 module_param(pretimeout, uint, 0);
 102 MODULE_PARM_DESC(pretimeout,
 103         "Watchdog pretimeout in seconds. (>=0, default="
 104         __MODULE_STRING(DEFAULT_PRETIMEOUT) ")");
 105
 106 static bool nowayout = WATCHDOG_NOWAYOUT;
 107 module_param(nowayout, bool, 0);
 108 MODULE_PARM_DESC(nowayout,
 109         "Watchdog cannot be stopped once started (default="
 110         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 111
 112 static int kempld_wdt_set_stage_action(struct kempld_wdt_data *wdt_data,
 113                                         struct kempld_wdt_stage *stage,
 114                                         u8 action)
 115 {
 116         struct kempld_device_data *pld = wdt_data->pld;
 117         u8 stage_cfg;
 118
 119         if (!stage || !stage->mask)
 120                 return -EINVAL;
 121
 122         kempld_get_mutex(pld);
 123         stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
 124         stage_cfg &= ~STAGE_CFG_ACTION_MASK;
 125         stage_cfg |= (action & STAGE_CFG_ACTION_MASK);
 126
 127         if (action == ACTION_RESET)
 128                 stage_cfg |= STAGE_CFG_ASSERT;
 129         else
 130                 stage_cfg &= ~STAGE_CFG_ASSERT;
 131
 132         kempld_write8(pld, KEMPLD_WDT_STAGE_CFG(stage->id), stage_cfg);
 133         kempld_release_mutex(pld);
 134
 135         return 0;
 136 }
 137
 138 static int kempld_wdt_set_stage_timeout(struct kempld_wdt_data *wdt_data,
 139                                         struct kempld_wdt_stage *stage,
 140                                         unsigned int timeout)
 141 {
 142         struct kempld_device_data *pld = wdt_data->pld;
 143         u32 prescaler = kempld_prescaler[PRESCALER_21];
 144         u64 stage_timeout64;
 145         u32 stage_timeout;
 146         u32 remainder;
 147         u8 stage_cfg;
 148
 149         if (!stage)
 150                 return -EINVAL;
 151
 152         stage_timeout64 = (u64)timeout * pld->pld_clock;
 153         remainder = do_div(stage_timeout64, prescaler);
 154         if (remainder)
 155                 stage_timeout64++;
 156
 157         if (stage_timeout64 > stage->mask)
 158                 return -EINVAL;
 159
 160         stage_timeout = stage_timeout64 & stage->mask;
 161
 162         kempld_get_mutex(pld);
 163         stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
 164         stage_cfg &= ~STAGE_CFG_PRESCALER_MASK;
 165         stage_cfg |= STAGE_CFG_SET_PRESCALER(PRESCALER_21);
 166         kempld_write8(pld, KEMPLD_WDT_STAGE_CFG(stage->id), stage_cfg);
 167         kempld_write32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id),
 168                         stage_timeout);
 169         kempld_release_mutex(pld);
 170
 171         return 0;
 172 }
 173
 174 /*
 175  * kempld_get_mutex must be called prior to calling this function.
 176  */
 177 static unsigned int kempld_wdt_get_timeout(struct kempld_wdt_data *wdt_data,
 178                                                 struct kempld_wdt_stage *stage)
 179 {
 180         struct kempld_device_data *pld = wdt_data->pld;
 181         unsigned int timeout;
 182         u64 stage_timeout;
 183         u32 prescaler;
 184         u32 remainder;
 185         u8 stage_cfg;
 186
 187         if (!stage->mask)
 188                 return 0;
 189
 190         stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
 191         stage_timeout = kempld_read32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id));
 192         prescaler = kempld_prescaler[STAGE_CFG_GET_PRESCALER(stage_cfg)];
 193
 194         stage_timeout = (stage_timeout & stage->mask) * prescaler;
 195         remainder = do_div(stage_timeout, pld->pld_clock);
 196         if (remainder)
 197                 stage_timeout++;
 198
 199         timeout = stage_timeout;
 200         WARN_ON_ONCE(timeout != stage_timeout);
 201
 202         return timeout;
 203 }
 204
 205 static int kempld_wdt_set_timeout(struct watchdog_device *wdd,
 206                                         unsigned int timeout)
 207 {
 208         struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 209         struct kempld_wdt_stage *pretimeout_stage;
 210         struct kempld_wdt_stage *timeout_stage;
 211         int ret;
 212
 213         timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];
 214         pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
 215
 216         if (pretimeout_stage->mask && wdt_data->pretimeout > 0)
 217                 timeout = wdt_data->pretimeout;
 218
 219         ret = kempld_wdt_set_stage_action(wdt_data, timeout_stage,
 220                                                 ACTION_RESET);
 221         if (ret)
 222                 return ret;
 223         ret = kempld_wdt_set_stage_timeout(wdt_data, timeout_stage,
 224                                                 timeout);
 225         if (ret)
 226                 return ret;
 227
 228         wdd->timeout = timeout;
 229         return 0;
 230 }
 231
 232 static int kempld_wdt_set_pretimeout(struct watchdog_device *wdd,
 233                                         unsigned int pretimeout)
 234 {
 235         struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 236         struct kempld_wdt_stage *pretimeout_stage;
 237         u8 action = ACTION_NONE;
 238         int ret;
 239
 240         pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
 241
 242         if (!pretimeout_stage->mask)
 243                 return -ENXIO;
 244
 245         if (pretimeout > wdd->timeout)
 246                 return -EINVAL;
 247
 248         if (pretimeout > 0)
 249                 action = ACTION_NMI;
 250
 251         ret = kempld_wdt_set_stage_action(wdt_data, pretimeout_stage,
 252                                                 action);
 253         if (ret)
 254                 return ret;
 255         ret = kempld_wdt_set_stage_timeout(wdt_data, pretimeout_stage,
 256                                                 wdd->timeout - pretimeout);
 257         if (ret)
 258                 return ret;
 259
 260         wdt_data->pretimeout = pretimeout;
 261         return 0;
 262 }
 263
 264 static void kempld_wdt_update_timeouts(struct kempld_wdt_data *wdt_data)
 265 {
 266         struct kempld_device_data *pld = wdt_data->pld;
 267         struct kempld_wdt_stage *pretimeout_stage;
 268         struct kempld_wdt_stage *timeout_stage;
 269         unsigned int pretimeout, timeout;
 270
 271         pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
 272         timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];
 273
 274         kempld_get_mutex(pld);
 275         pretimeout = kempld_wdt_get_timeout(wdt_data, pretimeout_stage);
 276         timeout = kempld_wdt_get_timeout(wdt_data, timeout_stage);
 277         kempld_release_mutex(pld);
 278
 279         if (pretimeout)
 280                 wdt_data->pretimeout = timeout;
 281         else
 282                 wdt_data->pretimeout = 0;
 283
 284         wdt_data->wdd.timeout = pretimeout + timeout;
 285 }
 286
 287 static int kempld_wdt_start(struct watchdog_device *wdd)
 288 {
 289         struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 290         struct kempld_device_data *pld = wdt_data->pld;
 291         u8 status;
 292         int ret;
 293
 294         ret = kempld_wdt_set_timeout(wdd, wdd->timeout);
 295         if (ret)
 296                 return ret;
 297
 298         kempld_get_mutex(pld);
 299         status = kempld_read8(pld, KEMPLD_WDT_CFG);
 300         status |= KEMPLD_WDT_CFG_ENABLE;
 301         kempld_write8(pld, KEMPLD_WDT_CFG, status);
 302         status = kempld_read8(pld, KEMPLD_WDT_CFG);
 303         kempld_release_mutex(pld);
 304
 305         /* Check if the watchdog was enabled */
 306         if (!(status & KEMPLD_WDT_CFG_ENABLE))
 307                 return -EACCES;
 308
 309         return 0;
 310 }
 311
 312 static int kempld_wdt_stop(struct watchdog_device *wdd)
 313 {
 314         struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 315         struct kempld_device_data *pld = wdt_data->pld;
 316         u8 status;
 317
 318         kempld_get_mutex(pld);
 319         status = kempld_read8(pld, KEMPLD_WDT_CFG);
 320         status &= ~KEMPLD_WDT_CFG_ENABLE;
 321         kempld_write8(pld, KEMPLD_WDT_CFG, status);
 322         status = kempld_read8(pld, KEMPLD_WDT_CFG);
 323         kempld_release_mutex(pld);
 324
 325         /* Check if the watchdog was disabled */
 326         if (status & KEMPLD_WDT_CFG_ENABLE)
 327                 return -EACCES;
 328
 329         return 0;
 330 }
 331
 332 static int kempld_wdt_keepalive(struct watchdog_device *wdd)
 333 {
 334         struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 335         struct kempld_device_data *pld = wdt_data->pld;
 336
 337         kempld_get_mutex(pld);
 338         kempld_write8(pld, KEMPLD_WDT_KICK, 'K');
 339         kempld_release_mutex(pld);
 340
 341         return 0;
 342 }
 343
 344 static long kempld_wdt_ioctl(struct watchdog_device *wdd, unsigned int cmd,
 345                                 unsigned long arg)
 346 {
 347         struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 348         void __user *argp = (void __user *)arg;
 349         int ret = -ENOIOCTLCMD;
 350         int __user *p = argp;
 351         int new_value;
 352
 353         switch (cmd) {
 354         case WDIOC_SETPRETIMEOUT:
 355                 if (get_user(new_value, p))
 356                         return -EFAULT;
 357                 ret = kempld_wdt_set_pretimeout(wdd, new_value);
 358                 if (ret)
 359                         return ret;
 360                 ret = kempld_wdt_keepalive(wdd);
 361                 break;
 362         case WDIOC_GETPRETIMEOUT:
 363                 ret = put_user(wdt_data->pretimeout, (int __user *)arg);
 364                 break;
 365         }
 366
 367         return ret;
 368 }
 369
 370 static int kempld_wdt_probe_stages(struct watchdog_device *wdd)
 371 {
 372         struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 373         struct kempld_device_data *pld = wdt_data->pld;
 374         struct kempld_wdt_stage *pretimeout_stage;
 375         struct kempld_wdt_stage *timeout_stage;
 376         u8 index, data, data_orig;
 377         u32 mask;
 378         int i, j;
 379
 380         pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
 381         timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];
 382
 383         pretimeout_stage->mask = 0;
 384         timeout_stage->mask = 0;
 385
 386         for (i = 0; i < 3; i++) {
 387                 index = KEMPLD_WDT_STAGE_TIMEOUT(i);
 388                 mask = 0;
 389
 390                 kempld_get_mutex(pld);
 391                 /* Probe each byte individually. */
 392                 for (j = 0; j < 4; j++) {
 393                         data_orig = kempld_read8(pld, index + j);
 394                         kempld_write8(pld, index + j, 0x00);
 395                         data = kempld_read8(pld, index + j);
 396                         /* A failed write means this byte is reserved */
 397                         if (data != 0x00)
 398                                 break;
 399                         kempld_write8(pld, index + j, data_orig);
 400                         mask |= 0xff << (j * 8);
 401                 }
 402                 kempld_release_mutex(pld);
 403
 404                 /* Assign available stages to timeout and pretimeout */
 405                 if (!timeout_stage->mask) {
 406                         timeout_stage->mask = mask;
 407                         timeout_stage->id = i;
 408                 } else {
 409                         if (pld->feature_mask & KEMPLD_FEATURE_BIT_NMI) {
 410                                 pretimeout_stage->mask = timeout_stage->mask;
 411                                 timeout_stage->mask = mask;
 412                                 pretimeout_stage->id = timeout_stage->id;
 413                                 timeout_stage->id = i;
 414                         }
 415                         break;
 416                 }
 417         }
 418
 419         if (!timeout_stage->mask)
 420                 return -ENODEV;
 421
 422         return 0;
 423 }
 424
 425 static struct watchdog_info kempld_wdt_info = {
 426         .identity       = "KEMPLD Watchdog",
 427         .options        = WDIOF_SETTIMEOUT |
 428                         WDIOF_KEEPALIVEPING |
 429                         WDIOF_MAGICCLOSE |
 430                         WDIOF_PRETIMEOUT
 431 };
 432
 433 static struct watchdog_ops kempld_wdt_ops = {
 434         .owner          = THIS_MODULE,
 435         .start          = kempld_wdt_start,
 436         .stop           = kempld_wdt_stop,
 437         .ping           = kempld_wdt_keepalive,
 438         .set_timeout    = kempld_wdt_set_timeout,
 439         .ioctl          = kempld_wdt_ioctl,
 440 };
 441
 442 static int kempld_wdt_probe(struct platform_device *pdev)
 443 {
 444         struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);
 445         struct kempld_wdt_data *wdt_data;
 446         struct device *dev = &pdev->dev;
 447         struct watchdog_device *wdd;
 448         u8 status;
 449         int ret = 0;
 450
 451         wdt_data = devm_kzalloc(dev, sizeof(*wdt_data), GFP_KERNEL);
 452         if (!wdt_data)
 453                 return -ENOMEM;
 454
 455         wdt_data->pld = pld;
 456         wdd = &wdt_data->wdd;
 457         wdd->parent = dev;
 458
 459         kempld_get_mutex(pld);
 460         status = kempld_read8(pld, KEMPLD_WDT_CFG);
 461         kempld_release_mutex(pld);
 462
 463         /* Enable nowayout if watchdog is already locked */
 464         if (status & (KEMPLD_WDT_CFG_ENABLE_LOCK |
 465                         KEMPLD_WDT_CFG_GLOBAL_LOCK)) {
 466                 if (!nowayout)
 467                         dev_warn(dev,
 468                                 "Forcing nowayout - watchdog lock enabled!\n");
 469                 nowayout = true;
 470         }
 471
 472         wdd->info = &kempld_wdt_info;
 473         wdd->ops = &kempld_wdt_ops;
 474
 475         watchdog_set_drvdata(wdd, wdt_data);
 476         watchdog_set_nowayout(wdd, nowayout);
 477
 478         ret = kempld_wdt_probe_stages(wdd);
 479         if (ret)
 480                 return ret;
 481
 482         kempld_wdt_set_timeout(wdd, timeout);
 483         kempld_wdt_set_pretimeout(wdd, pretimeout);
 484
 485         /* Check if watchdog is already enabled */
 486         if (status & KEMPLD_WDT_CFG_ENABLE) {
 487                 /* Get current watchdog settings */
 488                 kempld_wdt_update_timeouts(wdt_data);
 489                 dev_info(dev, "Watchdog was already enabled\n");
 490         }
 491
 492         platform_set_drvdata(pdev, wdt_data);
 493         ret = watchdog_register_device(wdd);
 494         if (ret)
 495                 return ret;
 496
 497         dev_info(dev, "Watchdog registered with %ds timeout\n", wdd->timeout);
 498
 499         return 0;
 500 }
 501
 502 static void kempld_wdt_shutdown(struct platform_device *pdev)
 503 {
 504         struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
 505
 506         kempld_wdt_stop(&wdt_data->wdd);
 507 }
 508
 509 static int kempld_wdt_remove(struct platform_device *pdev)
 510 {
 511         struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
 512         struct watchdog_device *wdd = &wdt_data->wdd;
 513         int ret = 0;
 514
 515         if (!nowayout)
 516                 ret = kempld_wdt_stop(wdd);
 517         watchdog_unregister_device(wdd);
 518
 519         return ret;
 520 }
 521
 522 #ifdef CONFIG_PM
 523 /* Disable watchdog if it is active during suspend */
 524 static int kempld_wdt_suspend(struct platform_device *pdev,
 525                                 pm_message_t message)
 526 {
 527         struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
 528         struct kempld_device_data *pld = wdt_data->pld;
 529         struct watchdog_device *wdd = &wdt_data->wdd;
 530
 531         kempld_get_mutex(pld);
 532         wdt_data->pm_status_store = kempld_read8(pld, KEMPLD_WDT_CFG);
 533         kempld_release_mutex(pld);
 534
 535         kempld_wdt_update_timeouts(wdt_data);
 536
 537         if (wdt_data->pm_status_store & KEMPLD_WDT_CFG_ENABLE)
 538                 return kempld_wdt_stop(wdd);
 539
 540         return 0;
 541 }
 542
 543 /* Enable watchdog and configure it if necessary */
 544 static int kempld_wdt_resume(struct platform_device *pdev)
 545 {
 546         struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
 547         struct watchdog_device *wdd = &wdt_data->wdd;
 548
 549         /*
 550          * If watchdog was stopped before suspend be sure it gets disabled
 551          * again, for the case BIOS has enabled it during resume
 552          */
 553         if (wdt_data->pm_status_store & KEMPLD_WDT_CFG_ENABLE)
 554                 return kempld_wdt_start(wdd);
 555         else
 556                 return kempld_wdt_stop(wdd);
 557 }
 558 #else
 559 #define kempld_wdt_suspend      NULL
 560 #define kempld_wdt_resume       NULL
 561 #endif
 562
 563 static struct platform_driver kempld_wdt_driver = {
 564         .driver         = {
 565                 .name   = "kempld-wdt",
 566                 .owner  = THIS_MODULE,
 567         },
 568         .probe          = kempld_wdt_probe,
 569         .remove         = kempld_wdt_remove,
 570         .shutdown       = kempld_wdt_shutdown,
 571         .suspend        = kempld_wdt_suspend,
 572         .resume         = kempld_wdt_resume,
 573 };
 574
 575 module_platform_driver(kempld_wdt_driver);
 576
 577 MODULE_DESCRIPTION("KEM PLD Watchdog Driver");
 578 MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
 579 MODULE_LICENSE("GPL");