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;
 144         u64 stage_timeout64;
 145         u32 stage_timeout;
 146         u32 remainder;
 147         u8 stage_cfg;
 148
 149         prescaler = kempld_prescaler[PRESCALER_21];
 150
 151         if (!stage)
 152                 return -EINVAL;
 153
 154         stage_timeout64 = (u64)timeout * pld->pld_clock;
 155         remainder = do_div(stage_timeout64, prescaler);
 156         if (remainder)
 157                 stage_timeout64++;
 158
 159         if (stage_timeout64 > stage->mask)
 160                 return -EINVAL;
 161
 162         stage_timeout = stage_timeout64 & stage->mask;
 163
 164         kempld_get_mutex(pld);
 165         stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
 166         stage_cfg &= ~STAGE_CFG_PRESCALER_MASK;
 167         stage_cfg |= STAGE_CFG_SET_PRESCALER(PRESCALER_21);
 168         kempld_write8(pld, KEMPLD_WDT_STAGE_CFG(stage->id), stage_cfg);
 169         kempld_write32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id),
 170                         stage_timeout);
 171         kempld_release_mutex(pld);
 172
 173         return 0;
 174 }
 175
 176 /*
 177  * kempld_get_mutex must be called prior to calling this function.
 178  */
 179 static unsigned int kempld_wdt_get_timeout(struct kempld_wdt_data *wdt_data,
 180                                                 struct kempld_wdt_stage *stage)
 181 {
 182         struct kempld_device_data *pld = wdt_data->pld;
 183         unsigned int timeout;
 184         u64 stage_timeout;
 185         u32 prescaler;
 186         u32 remainder;
 187         u8 stage_cfg;
 188
 189         if (!stage->mask)
 190                 return 0;
 191
 192         stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
 193         stage_timeout = kempld_read32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id));
 194         prescaler = kempld_prescaler[STAGE_CFG_GET_PRESCALER(stage_cfg)];
 195
 196         stage_timeout = (stage_timeout & stage->mask) * prescaler;
 197         remainder = do_div(stage_timeout, pld->pld_clock);
 198         if (remainder)
 199                 stage_timeout++;
 200
 201         timeout = stage_timeout;
 202         WARN_ON_ONCE(timeout != stage_timeout);
 203
 204         return timeout;
 205 }
 206
 207 static int kempld_wdt_set_timeout(struct watchdog_device *wdd,
 208                                         unsigned int timeout)
 209 {
 210         struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 211         struct kempld_wdt_stage *pretimeout_stage;
 212         struct kempld_wdt_stage *timeout_stage;
 213         int ret;
 214
 215         timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];
 216         pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
 217
 218         if (pretimeout_stage->mask && wdt_data->pretimeout > 0)
 219                 timeout = wdt_data->pretimeout;
 220
 221         ret = kempld_wdt_set_stage_action(wdt_data, timeout_stage,
 222                                                 ACTION_RESET);
 223         if (ret)
 224                 return ret;
 225         ret = kempld_wdt_set_stage_timeout(wdt_data, timeout_stage,
 226                                                 timeout);
 227         if (ret)
 228                 return ret;
 229
 230         wdd->timeout = timeout;
 231         return 0;
 232 }
 233
 234 static int kempld_wdt_set_pretimeout(struct watchdog_device *wdd,
 235                                         unsigned int pretimeout)
 236 {
 237         struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 238         struct kempld_wdt_stage *pretimeout_stage;
 239         u8 action = ACTION_NONE;
 240         int ret;
 241
 242         pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
 243
 244         if (!pretimeout_stage->mask)
 245                 return -ENXIO;
 246
 247         if (pretimeout > wdd->timeout)
 248                 return -EINVAL;
 249
 250         if (pretimeout > 0)
 251                 action = ACTION_NMI;
 252
 253         ret = kempld_wdt_set_stage_action(wdt_data, pretimeout_stage,
 254                                                 action);
 255         if (ret)
 256                 return ret;
 257         ret = kempld_wdt_set_stage_timeout(wdt_data, pretimeout_stage,
 258                                                 wdd->timeout - pretimeout);
 259         if (ret)
 260                 return ret;
 261
 262         wdt_data->pretimeout = pretimeout;
 263         return 0;
 264 }
 265
 266 static void kempld_wdt_update_timeouts(struct kempld_wdt_data *wdt_data)
 267 {
 268         struct kempld_device_data *pld = wdt_data->pld;
 269         struct kempld_wdt_stage *pretimeout_stage;
 270         struct kempld_wdt_stage *timeout_stage;
 271         unsigned int pretimeout, timeout;
 272
 273         pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
 274         timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];
 275
 276         kempld_get_mutex(pld);
 277         pretimeout = kempld_wdt_get_timeout(wdt_data, pretimeout_stage);
 278         timeout = kempld_wdt_get_timeout(wdt_data, timeout_stage);
 279         kempld_release_mutex(pld);
 280
 281         if (pretimeout)
 282                 wdt_data->pretimeout = timeout;
 283         else
 284                 wdt_data->pretimeout = 0;
 285
 286         wdt_data->wdd.timeout = pretimeout + timeout;
 287 }
 288
 289 static int kempld_wdt_start(struct watchdog_device *wdd)
 290 {
 291         struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 292         struct kempld_device_data *pld = wdt_data->pld;
 293         u8 status;
 294         int ret;
 295
 296         ret = kempld_wdt_set_timeout(wdd, wdd->timeout);
 297         if (ret)
 298                 return ret;
 299
 300         kempld_get_mutex(pld);
 301         status = kempld_read8(pld, KEMPLD_WDT_CFG);
 302         status |= KEMPLD_WDT_CFG_ENABLE;
 303         kempld_write8(pld, KEMPLD_WDT_CFG, status);
 304         status = kempld_read8(pld, KEMPLD_WDT_CFG);
 305         kempld_release_mutex(pld);
 306
 307         /* Check if the watchdog was enabled */
 308         if (!(status & KEMPLD_WDT_CFG_ENABLE))
 309                 return -EACCES;
 310
 311         return 0;
 312 }
 313
 314 static int kempld_wdt_stop(struct watchdog_device *wdd)
 315 {
 316         struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 317         struct kempld_device_data *pld = wdt_data->pld;
 318         u8 status;
 319
 320         kempld_get_mutex(pld);
 321         status = kempld_read8(pld, KEMPLD_WDT_CFG);
 322         status &= ~KEMPLD_WDT_CFG_ENABLE;
 323         kempld_write8(pld, KEMPLD_WDT_CFG, status);
 324         status = kempld_read8(pld, KEMPLD_WDT_CFG);
 325         kempld_release_mutex(pld);
 326
 327         /* Check if the watchdog was disabled */
 328         if (status & KEMPLD_WDT_CFG_ENABLE)
 329                 return -EACCES;
 330
 331         return 0;
 332 }
 333
 334 static int kempld_wdt_keepalive(struct watchdog_device *wdd)
 335 {
 336         struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 337         struct kempld_device_data *pld = wdt_data->pld;
 338
 339         kempld_get_mutex(pld);
 340         kempld_write8(pld, KEMPLD_WDT_KICK, 'K');
 341         kempld_release_mutex(pld);
 342
 343         return 0;
 344 }
 345
 346 static long kempld_wdt_ioctl(struct watchdog_device *wdd, unsigned int cmd,
 347                                 unsigned long arg)
 348 {
 349         struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 350         void __user *argp = (void __user *)arg;
 351         int ret = -ENOIOCTLCMD;
 352         int __user *p = argp;
 353         int new_value;
 354
 355         switch (cmd) {
 356         case WDIOC_SETPRETIMEOUT:
 357                 if (get_user(new_value, p))
 358                         return -EFAULT;
 359                 ret = kempld_wdt_set_pretimeout(wdd, new_value);
 360                 if (ret)
 361                         return ret;
 362                 ret = kempld_wdt_keepalive(wdd);
 363                 break;
 364         case WDIOC_GETPRETIMEOUT:
 365                 ret = put_user(wdt_data->pretimeout, (int __user *)arg);
 366                 break;
 367         }
 368
 369         return ret;
 370 }
 371
 372 static int kempld_wdt_probe_stages(struct watchdog_device *wdd)
 373 {
 374         struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
 375         struct kempld_device_data *pld = wdt_data->pld;
 376         struct kempld_wdt_stage *pretimeout_stage;
 377         struct kempld_wdt_stage *timeout_stage;
 378         u8 index, data, data_orig;
 379         u32 mask;
 380         int i, j;
 381
 382         pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
 383         timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];
 384
 385         pretimeout_stage->mask = 0;
 386         timeout_stage->mask = 0;
 387
 388         for (i = 0; i < 3; i++) {
 389                 index = KEMPLD_WDT_STAGE_TIMEOUT(i);
 390                 mask = 0;
 391
 392                 kempld_get_mutex(pld);
 393                 /* Probe each byte individually. */
 394                 for (j = 0; j < 4; j++) {
 395                         data_orig = kempld_read8(pld, index + j);
 396                         kempld_write8(pld, index + j, 0x00);
 397                         data = kempld_read8(pld, index + j);
 398                         /* A failed write means this byte is reserved */
 399                         if (data != 0x00)
 400                                 break;
 401                         kempld_write8(pld, index + j, data_orig);
 402                         mask |= 0xff << (j * 8);
 403                 }
 404                 kempld_release_mutex(pld);
 405
 406                 /* Assign available stages to timeout and pretimeout */
 407                 if (!timeout_stage->mask) {
 408                         timeout_stage->mask = mask;
 409                         timeout_stage->id = i;
 410                 } else {
 411                         if (pld->feature_mask & KEMPLD_FEATURE_BIT_NMI) {
 412                                 pretimeout_stage->mask = timeout_stage->mask;
 413                                 timeout_stage->mask = mask;
 414                                 pretimeout_stage->id = timeout_stage->id;
 415                                 timeout_stage->id = i;
 416                         }
 417                         break;
 418                 }
 419         }
 420
 421         if (!timeout_stage->mask)
 422                 return -ENODEV;
 423
 424         return 0;
 425 }
 426
 427 static const struct watchdog_info kempld_wdt_info = {
 428         .identity       = "KEMPLD Watchdog",
 429         .options        = WDIOF_SETTIMEOUT |
 430                         WDIOF_KEEPALIVEPING |
 431                         WDIOF_MAGICCLOSE |
 432                         WDIOF_PRETIMEOUT
 433 };
 434
 435 static const struct watchdog_ops kempld_wdt_ops = {
 436         .owner          = THIS_MODULE,
 437         .start          = kempld_wdt_start,
 438         .stop           = kempld_wdt_stop,
 439         .ping           = kempld_wdt_keepalive,
 440         .set_timeout    = kempld_wdt_set_timeout,
 441         .ioctl          = kempld_wdt_ioctl,
 442 };
 443
 444 static int kempld_wdt_probe(struct platform_device *pdev)
 445 {
 446         struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);
 447         struct kempld_wdt_data *wdt_data;
 448         struct device *dev = &pdev->dev;
 449         struct watchdog_device *wdd;
 450         u8 status;
 451         int ret = 0;
 452
 453         wdt_data = devm_kzalloc(dev, sizeof(*wdt_data), GFP_KERNEL);
 454         if (!wdt_data)
 455                 return -ENOMEM;
 456
 457         wdt_data->pld = pld;
 458         wdd = &wdt_data->wdd;
 459         wdd->parent = dev;
 460
 461         kempld_get_mutex(pld);
 462         status = kempld_read8(pld, KEMPLD_WDT_CFG);
 463         kempld_release_mutex(pld);
 464
 465         /* Enable nowayout if watchdog is already locked */
 466         if (status & (KEMPLD_WDT_CFG_ENABLE_LOCK |
 467                         KEMPLD_WDT_CFG_GLOBAL_LOCK)) {
 468                 if (!nowayout)
 469                         dev_warn(dev,
 470                                 "Forcing nowayout - watchdog lock enabled!\n");
 471                 nowayout = true;
 472         }
 473
 474         wdd->info = &kempld_wdt_info;
 475         wdd->ops = &kempld_wdt_ops;
 476
 477         watchdog_set_drvdata(wdd, wdt_data);
 478         watchdog_set_nowayout(wdd, nowayout);
 479
 480         ret = kempld_wdt_probe_stages(wdd);
 481         if (ret)
 482                 return ret;
 483
 484         kempld_wdt_set_timeout(wdd, timeout);
 485         kempld_wdt_set_pretimeout(wdd, pretimeout);
 486
 487         /* Check if watchdog is already enabled */
 488         if (status & KEMPLD_WDT_CFG_ENABLE) {
 489                 /* Get current watchdog settings */
 490                 kempld_wdt_update_timeouts(wdt_data);
 491                 dev_info(dev, "Watchdog was already enabled\n");
 492         }
 493
 494         platform_set_drvdata(pdev, wdt_data);
 495         ret = watchdog_register_device(wdd);
 496         if (ret)
 497                 return ret;
 498
 499         dev_info(dev, "Watchdog registered with %ds timeout\n", wdd->timeout);
 500
 501         return 0;
 502 }
 503
 504 static void kempld_wdt_shutdown(struct platform_device *pdev)
 505 {
 506         struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
 507
 508         kempld_wdt_stop(&wdt_data->wdd);
 509 }
 510
 511 static int kempld_wdt_remove(struct platform_device *pdev)
 512 {
 513         struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
 514         struct watchdog_device *wdd = &wdt_data->wdd;
 515         int ret = 0;
 516
 517         if (!nowayout)
 518                 ret = kempld_wdt_stop(wdd);
 519         watchdog_unregister_device(wdd);
 520
 521         return ret;
 522 }
 523
 524 #ifdef CONFIG_PM
 525 /* Disable watchdog if it is active during suspend */
 526 static int kempld_wdt_suspend(struct platform_device *pdev,
 527                                 pm_message_t message)
 528 {
 529         struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
 530         struct kempld_device_data *pld = wdt_data->pld;
 531         struct watchdog_device *wdd = &wdt_data->wdd;
 532
 533         kempld_get_mutex(pld);
 534         wdt_data->pm_status_store = kempld_read8(pld, KEMPLD_WDT_CFG);
 535         kempld_release_mutex(pld);
 536
 537         kempld_wdt_update_timeouts(wdt_data);
 538
 539         if (wdt_data->pm_status_store & KEMPLD_WDT_CFG_ENABLE)
 540                 return kempld_wdt_stop(wdd);
 541
 542         return 0;
 543 }
 544
 545 /* Enable watchdog and configure it if necessary */
 546 static int kempld_wdt_resume(struct platform_device *pdev)
 547 {
 548         struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
 549         struct watchdog_device *wdd = &wdt_data->wdd;
 550
 551         /*
 552          * If watchdog was stopped before suspend be sure it gets disabled
 553          * again, for the case BIOS has enabled it during resume
 554          */
 555         if (wdt_data->pm_status_store & KEMPLD_WDT_CFG_ENABLE)
 556                 return kempld_wdt_start(wdd);
 557         else
 558                 return kempld_wdt_stop(wdd);
 559 }
 560 #else
 561 #define kempld_wdt_suspend      NULL
 562 #define kempld_wdt_resume       NULL
 563 #endif
 564
 565 static struct platform_driver kempld_wdt_driver = {
 566         .driver         = {
 567                 .name   = "kempld-wdt",
 568         },
 569         .probe          = kempld_wdt_probe,
 570         .remove         = kempld_wdt_remove,
 571         .shutdown       = kempld_wdt_shutdown,
 572         .suspend        = kempld_wdt_suspend,
 573         .resume         = kempld_wdt_resume,
 574 };
 575
 576 module_platform_driver(kempld_wdt_driver);
 577
 578 MODULE_DESCRIPTION("KEM PLD Watchdog Driver");
 579 MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
 580 MODULE_LICENSE("GPL");