drivers/acpi/ec.c

   1 /*
   2  *  ec.c - ACPI Embedded Controller Driver (v2.2)
   3  *
   4  *  Copyright (C) 2001-2014 Intel Corporation
   5  *    Author: 2014       Lv Zheng <lv.zheng@intel.com>
   6  *            2006, 2007 Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
   7  *            2006       Denis Sadykov <denis.m.sadykov@intel.com>
   8  *            2004       Luming Yu <luming.yu@intel.com>
   9  *            2001, 2002 Andy Grover <andrew.grover@intel.com>
  10  *            2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
  11  *  Copyright (C) 2008      Alexey Starikovskiy <astarikovskiy@suse.de>
  12  *
  13  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  14  *
  15  *  This program is free software; you can redistribute it and/or modify
  16  *  it under the terms of the GNU General Public License as published by
  17  *  the Free Software Foundation; either version 2 of the License, or (at
  18  *  your option) any later version.
  19  *
  20  *  This program is distributed in the hope that it will be useful, but
  21  *  WITHOUT ANY WARRANTY; without even the implied warranty of
  22  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  23  *  General Public License for more details.
  24  *
  25  *  You should have received a copy of the GNU General Public License along
  26  *  with this program; if not, write to the Free Software Foundation, Inc.,
  27  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  28  *
  29  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  30  */
  31
  32 /* Uncomment next line to get verbose printout */
  33 /* #define DEBUG */
  34 #define pr_fmt(fmt) "ACPI : EC: " fmt
  35
  36 #include <linux/kernel.h>
  37 #include <linux/module.h>
  38 #include <linux/init.h>
  39 #include <linux/types.h>
  40 #include <linux/delay.h>
  41 #include <linux/interrupt.h>
  42 #include <linux/list.h>
  43 #include <linux/spinlock.h>
  44 #include <linux/slab.h>
  45 #include <linux/acpi.h>
  46 #include <linux/dmi.h>
  47 #include <asm/io.h>
  48
  49 #include "internal.h"
  50
  51 #define ACPI_EC_CLASS                   "embedded_controller"
  52 #define ACPI_EC_DEVICE_NAME             "Embedded Controller"
  53 #define ACPI_EC_FILE_INFO               "info"
  54
  55 /* EC status register */
  56 #define ACPI_EC_FLAG_OBF        0x01    /* Output buffer full */
  57 #define ACPI_EC_FLAG_IBF        0x02    /* Input buffer full */
  58 #define ACPI_EC_FLAG_CMD        0x08    /* Input buffer contains a command */
  59 #define ACPI_EC_FLAG_BURST      0x10    /* burst mode */
  60 #define ACPI_EC_FLAG_SCI        0x20    /* EC-SCI occurred */
  61
  62 /* EC commands */
  63 enum ec_command {
  64         ACPI_EC_COMMAND_READ = 0x80,
  65         ACPI_EC_COMMAND_WRITE = 0x81,
  66         ACPI_EC_BURST_ENABLE = 0x82,
  67         ACPI_EC_BURST_DISABLE = 0x83,
  68         ACPI_EC_COMMAND_QUERY = 0x84,
  69 };
  70
  71 #define ACPI_EC_DELAY           500     /* Wait 500ms max. during EC ops */
  72 #define ACPI_EC_UDELAY_GLK      1000    /* Wait 1ms max. to get global lock */
  73 #define ACPI_EC_MSI_UDELAY      550     /* Wait 550us for MSI EC */
  74 #define ACPI_EC_CLEAR_MAX       100     /* Maximum number of events to query
  75                                          * when trying to clear the EC */
  76
  77 enum {
  78         EC_FLAGS_QUERY_PENDING,         /* Query is pending */
  79         EC_FLAGS_GPE_STORM,             /* GPE storm detected */
  80         EC_FLAGS_HANDLERS_INSTALLED,    /* Handlers for GPE and
  81                                          * OpReg are installed */
  82         EC_FLAGS_BLOCKED,               /* Transactions are blocked */
  83 };
  84
  85 #define ACPI_EC_COMMAND_POLL            0x01 /* Available for command byte */
  86 #define ACPI_EC_COMMAND_COMPLETE        0x02 /* Completed last byte */
  87
  88 /* ec.c is compiled in acpi namespace so this shows up as acpi.ec_delay param */
  89 static unsigned int ec_delay __read_mostly = ACPI_EC_DELAY;
  90 module_param(ec_delay, uint, 0644);
  91 MODULE_PARM_DESC(ec_delay, "Timeout(ms) waited until an EC command completes");
  92
  93 /*
  94  * If the number of false interrupts per one transaction exceeds
  95  * this threshold, will think there is a GPE storm happened and
  96  * will disable the GPE for normal transaction.
  97  */
  98 static unsigned int ec_storm_threshold  __read_mostly = 8;
  99 module_param(ec_storm_threshold, uint, 0644);
 100 MODULE_PARM_DESC(ec_storm_threshold, "Maxim false GPE numbers not considered as GPE storm");
 101
 102 struct acpi_ec_query_handler {
 103         struct list_head node;
 104         acpi_ec_query_func func;
 105         acpi_handle handle;
 106         void *data;
 107         u8 query_bit;
 108 };
 109
 110 struct transaction {
 111         const u8 *wdata;
 112         u8 *rdata;
 113         unsigned short irq_count;
 114         u8 command;
 115         u8 wi;
 116         u8 ri;
 117         u8 wlen;
 118         u8 rlen;
 119         u8 flags;
 120 };
 121
 122 struct acpi_ec *boot_ec, *first_ec;
 123 EXPORT_SYMBOL(first_ec);
 124
 125 static int EC_FLAGS_MSI; /* Out-of-spec MSI controller */
 126 static int EC_FLAGS_VALIDATE_ECDT; /* ASUStec ECDTs need to be validated */
 127 static int EC_FLAGS_SKIP_DSDT_SCAN; /* Not all BIOS survive early DSDT scan */
 128 static int EC_FLAGS_CLEAR_ON_RESUME; /* Needs acpi_ec_clear() on boot/resume */
 129 static int EC_FLAGS_QUERY_HANDSHAKE; /* Needs QR_EC issued when SCI_EVT set */
 130
 131 /* --------------------------------------------------------------------------
 132  *                           Transaction Management
 133  * -------------------------------------------------------------------------- */
 134
 135 static inline u8 acpi_ec_read_status(struct acpi_ec *ec)
 136 {
 137         u8 x = inb(ec->command_addr);
 138
 139         pr_debug("EC_SC(R) = 0x%2.2x "
 140                  "SCI_EVT=%d BURST=%d CMD=%d IBF=%d OBF=%d\n",
 141                  x,
 142                  !!(x & ACPI_EC_FLAG_SCI),
 143                  !!(x & ACPI_EC_FLAG_BURST),
 144                  !!(x & ACPI_EC_FLAG_CMD),
 145                  !!(x & ACPI_EC_FLAG_IBF),
 146                  !!(x & ACPI_EC_FLAG_OBF));
 147         return x;
 148 }
 149
 150 static inline u8 acpi_ec_read_data(struct acpi_ec *ec)
 151 {
 152         u8 x = inb(ec->data_addr);
 153
 154         pr_debug("EC_DATA(R) = 0x%2.2x\n", x);
 155         return x;
 156 }
 157
 158 static inline void acpi_ec_write_cmd(struct acpi_ec *ec, u8 command)
 159 {
 160         pr_debug("EC_SC(W) = 0x%2.2x\n", command);
 161         outb(command, ec->command_addr);
 162 }
 163
 164 static inline void acpi_ec_write_data(struct acpi_ec *ec, u8 data)
 165 {
 166         pr_debug("EC_DATA(W) = 0x%2.2x\n", data);
 167         outb(data, ec->data_addr);
 168 }
 169
 170 #ifdef DEBUG
 171 static const char *acpi_ec_cmd_string(u8 cmd)
 172 {
 173         switch (cmd) {
 174         case 0x80:
 175                 return "RD_EC";
 176         case 0x81:
 177                 return "WR_EC";
 178         case 0x82:
 179                 return "BE_EC";
 180         case 0x83:
 181                 return "BD_EC";
 182         case 0x84:
 183                 return "QR_EC";
 184         }
 185         return "UNKNOWN";
 186 }
 187 #else
 188 #define acpi_ec_cmd_string(cmd)         "UNDEF"
 189 #endif
 190
 191 static int ec_transaction_completed(struct acpi_ec *ec)
 192 {
 193         unsigned long flags;
 194         int ret = 0;
 195
 196         spin_lock_irqsave(&ec->lock, flags);
 197         if (ec->curr && (ec->curr->flags & ACPI_EC_COMMAND_COMPLETE))
 198                 ret = 1;
 199         spin_unlock_irqrestore(&ec->lock, flags);
 200         return ret;
 201 }
 202
 203 static bool advance_transaction(struct acpi_ec *ec)
 204 {
 205         struct transaction *t;
 206         u8 status;
 207         bool wakeup = false;
 208
 209         pr_debug("===== %s (%d) =====\n",
 210                  in_interrupt() ? "IRQ" : "TASK", smp_processor_id());
 211         status = acpi_ec_read_status(ec);
 212         t = ec->curr;
 213         if (!t)
 214                 goto err;
 215         if (t->flags & ACPI_EC_COMMAND_POLL) {
 216                 if (t->wlen > t->wi) {
 217                         if ((status & ACPI_EC_FLAG_IBF) == 0)
 218                                 acpi_ec_write_data(ec, t->wdata[t->wi++]);
 219                         else
 220                                 goto err;
 221                 } else if (t->rlen > t->ri) {
 222                         if ((status & ACPI_EC_FLAG_OBF) == 1) {
 223                                 t->rdata[t->ri++] = acpi_ec_read_data(ec);
 224                                 if (t->rlen == t->ri) {
 225                                         t->flags |= ACPI_EC_COMMAND_COMPLETE;
 226                                         if (t->command == ACPI_EC_COMMAND_QUERY)
 227                                                 pr_debug("***** Command(%s) hardware completion *****\n",
 228                                                          acpi_ec_cmd_string(t->command));
 229                                         wakeup = true;
 230                                 }
 231                         } else
 232                                 goto err;
 233                 } else if (t->wlen == t->wi &&
 234                            (status & ACPI_EC_FLAG_IBF) == 0) {
 235                         t->flags |= ACPI_EC_COMMAND_COMPLETE;
 236                         wakeup = true;
 237                 }
 238                 return wakeup;
 239         } else {
 240                 if (EC_FLAGS_QUERY_HANDSHAKE &&
 241                     !(status & ACPI_EC_FLAG_SCI) &&
 242                     (t->command == ACPI_EC_COMMAND_QUERY)) {
 243                         t->flags |= ACPI_EC_COMMAND_POLL;
 244                         t->rdata[t->ri++] = 0x00;
 245                         t->flags |= ACPI_EC_COMMAND_COMPLETE;
 246                         pr_debug("***** Command(%s) software completion *****\n",
 247                                  acpi_ec_cmd_string(t->command));
 248                         wakeup = true;
 249                 } else if ((status & ACPI_EC_FLAG_IBF) == 0) {
 250                         acpi_ec_write_cmd(ec, t->command);
 251                         t->flags |= ACPI_EC_COMMAND_POLL;
 252                 } else
 253                         goto err;
 254                 return wakeup;
 255         }
 256 err:
 257         /*
 258          * If SCI bit is set, then don't think it's a false IRQ
 259          * otherwise will take a not handled IRQ as a false one.
 260          */
 261         if (!(status & ACPI_EC_FLAG_SCI)) {
 262                 if (in_interrupt() && t)
 263                         ++t->irq_count;
 264         }
 265         return wakeup;
 266 }
 267
 268 static void start_transaction(struct acpi_ec *ec)
 269 {
 270         ec->curr->irq_count = ec->curr->wi = ec->curr->ri = 0;
 271         ec->curr->flags = 0;
 272         (void)advance_transaction(ec);
 273 }
 274
 275 static int acpi_ec_sync_query(struct acpi_ec *ec, u8 *data);
 276
 277 static int ec_check_sci_sync(struct acpi_ec *ec, u8 state)
 278 {
 279         if (state & ACPI_EC_FLAG_SCI) {
 280                 if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags))
 281                         return acpi_ec_sync_query(ec, NULL);
 282         }
 283         return 0;
 284 }
 285
 286 static int ec_poll(struct acpi_ec *ec)
 287 {
 288         unsigned long flags;
 289         int repeat = 5; /* number of command restarts */
 290
 291         while (repeat--) {
 292                 unsigned long delay = jiffies +
 293                         msecs_to_jiffies(ec_delay);
 294                 do {
 295                         /* don't sleep with disabled interrupts */
 296                         if (EC_FLAGS_MSI || irqs_disabled()) {
 297                                 udelay(ACPI_EC_MSI_UDELAY);
 298                                 if (ec_transaction_completed(ec))
 299                                         return 0;
 300                         } else {
 301                                 if (wait_event_timeout(ec->wait,
 302                                                 ec_transaction_completed(ec),
 303                                                 msecs_to_jiffies(1)))
 304                                         return 0;
 305                         }
 306                         spin_lock_irqsave(&ec->lock, flags);
 307                         (void)advance_transaction(ec);
 308                         spin_unlock_irqrestore(&ec->lock, flags);
 309                 } while (time_before(jiffies, delay));
 310                 pr_debug("controller reset, restart transaction\n");
 311                 spin_lock_irqsave(&ec->lock, flags);
 312                 start_transaction(ec);
 313                 spin_unlock_irqrestore(&ec->lock, flags);
 314         }
 315         return -ETIME;
 316 }
 317
 318 static int acpi_ec_transaction_unlocked(struct acpi_ec *ec,
 319                                         struct transaction *t)
 320 {
 321         unsigned long tmp;
 322         int ret = 0;
 323
 324         if (EC_FLAGS_MSI)
 325                 udelay(ACPI_EC_MSI_UDELAY);
 326         /* start transaction */
 327         spin_lock_irqsave(&ec->lock, tmp);
 328         /* following two actions should be kept atomic */
 329         ec->curr = t;
 330         pr_debug("***** Command(%s) started *****\n",
 331                  acpi_ec_cmd_string(t->command));
 332         start_transaction(ec);
 333         if (ec->curr->command == ACPI_EC_COMMAND_QUERY) {
 334                 clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
 335                 pr_debug("***** Event stopped *****\n");
 336         }
 337         spin_unlock_irqrestore(&ec->lock, tmp);
 338         ret = ec_poll(ec);
 339         spin_lock_irqsave(&ec->lock, tmp);
 340         pr_debug("***** Command(%s) stopped *****\n",
 341                  acpi_ec_cmd_string(t->command));
 342         ec->curr = NULL;
 343         spin_unlock_irqrestore(&ec->lock, tmp);
 344         return ret;
 345 }
 346
 347 static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t)
 348 {
 349         int status;
 350         u32 glk;
 351
 352         if (!ec || (!t) || (t->wlen && !t->wdata) || (t->rlen && !t->rdata))
 353                 return -EINVAL;
 354         if (t->rdata)
 355                 memset(t->rdata, 0, t->rlen);
 356         mutex_lock(&ec->mutex);
 357         if (test_bit(EC_FLAGS_BLOCKED, &ec->flags)) {
 358                 status = -EINVAL;
 359                 goto unlock;
 360         }
 361         if (ec->global_lock) {
 362                 status = acpi_acquire_global_lock(ACPI_EC_UDELAY_GLK, &glk);
 363                 if (ACPI_FAILURE(status)) {
 364                         status = -ENODEV;
 365                         goto unlock;
 366                 }
 367         }
 368         /* disable GPE during transaction if storm is detected */
 369         if (test_bit(EC_FLAGS_GPE_STORM, &ec->flags)) {
 370                 /* It has to be disabled, so that it doesn't trigger. */
 371                 acpi_disable_gpe(NULL, ec->gpe);
 372         }
 373
 374         status = acpi_ec_transaction_unlocked(ec, t);
 375
 376         /* check if we received SCI during transaction */
 377         ec_check_sci_sync(ec, acpi_ec_read_status(ec));
 378         if (test_bit(EC_FLAGS_GPE_STORM, &ec->flags)) {
 379                 msleep(1);
 380                 /* It is safe to enable the GPE outside of the transaction. */
 381                 acpi_enable_gpe(NULL, ec->gpe);
 382         } else if (t->irq_count > ec_storm_threshold) {
 383                 pr_info("GPE storm detected(%d GPEs), "
 384                         "transactions will use polling mode\n",
 385                         t->irq_count);
 386                 set_bit(EC_FLAGS_GPE_STORM, &ec->flags);
 387         }
 388         if (ec->global_lock)
 389                 acpi_release_global_lock(glk);
 390 unlock:
 391         mutex_unlock(&ec->mutex);
 392         return status;
 393 }
 394
 395 static int acpi_ec_burst_enable(struct acpi_ec *ec)
 396 {
 397         u8 d;
 398         struct transaction t = {.command = ACPI_EC_BURST_ENABLE,
 399                                 .wdata = NULL, .rdata = &d,
 400                                 .wlen = 0, .rlen = 1};
 401
 402         return acpi_ec_transaction(ec, &t);
 403 }
 404
 405 static int acpi_ec_burst_disable(struct acpi_ec *ec)
 406 {
 407         struct transaction t = {.command = ACPI_EC_BURST_DISABLE,
 408                                 .wdata = NULL, .rdata = NULL,
 409                                 .wlen = 0, .rlen = 0};
 410
 411         return (acpi_ec_read_status(ec) & ACPI_EC_FLAG_BURST) ?
 412                                 acpi_ec_transaction(ec, &t) : 0;
 413 }
 414
 415 static int acpi_ec_read(struct acpi_ec *ec, u8 address, u8 *data)
 416 {
 417         int result;
 418         u8 d;
 419         struct transaction t = {.command = ACPI_EC_COMMAND_READ,
 420                                 .wdata = &address, .rdata = &d,
 421                                 .wlen = 1, .rlen = 1};
 422
 423         result = acpi_ec_transaction(ec, &t);
 424         *data = d;
 425         return result;
 426 }
 427
 428 static int acpi_ec_write(struct acpi_ec *ec, u8 address, u8 data)
 429 {
 430         u8 wdata[2] = { address, data };
 431         struct transaction t = {.command = ACPI_EC_COMMAND_WRITE,
 432                                 .wdata = wdata, .rdata = NULL,
 433                                 .wlen = 2, .rlen = 0};
 434
 435         return acpi_ec_transaction(ec, &t);
 436 }
 437
 438 int ec_read(u8 addr, u8 *val)
 439 {
 440         int err;
 441         u8 temp_data;
 442
 443         if (!first_ec)
 444                 return -ENODEV;
 445
 446         err = acpi_ec_read(first_ec, addr, &temp_data);
 447
 448         if (!err) {
 449                 *val = temp_data;
 450                 return 0;
 451         }
 452         return err;
 453 }
 454 EXPORT_SYMBOL(ec_read);
 455
 456 int ec_write(u8 addr, u8 val)
 457 {
 458         int err;
 459
 460         if (!first_ec)
 461                 return -ENODEV;
 462
 463         err = acpi_ec_write(first_ec, addr, val);
 464
 465         return err;
 466 }
 467 EXPORT_SYMBOL(ec_write);
 468
 469 int ec_transaction(u8 command,
 470                    const u8 *wdata, unsigned wdata_len,
 471                    u8 *rdata, unsigned rdata_len)
 472 {
 473         struct transaction t = {.command = command,
 474                                 .wdata = wdata, .rdata = rdata,
 475                                 .wlen = wdata_len, .rlen = rdata_len};
 476
 477         if (!first_ec)
 478                 return -ENODEV;
 479
 480         return acpi_ec_transaction(first_ec, &t);
 481 }
 482 EXPORT_SYMBOL(ec_transaction);
 483
 484 /* Get the handle to the EC device */
 485 acpi_handle ec_get_handle(void)
 486 {
 487         if (!first_ec)
 488                 return NULL;
 489         return first_ec->handle;
 490 }
 491 EXPORT_SYMBOL(ec_get_handle);
 492
 493 /*
 494  * Process _Q events that might have accumulated in the EC.
 495  * Run with locked ec mutex.
 496  */
 497 static void acpi_ec_clear(struct acpi_ec *ec)
 498 {
 499         int i, status;
 500         u8 value = 0;
 501
 502         for (i = 0; i < ACPI_EC_CLEAR_MAX; i++) {
 503                 status = acpi_ec_sync_query(ec, &value);
 504                 if (status || !value)
 505                         break;
 506         }
 507
 508         if (unlikely(i == ACPI_EC_CLEAR_MAX))
 509                 pr_warn("Warning: Maximum of %d stale EC events cleared\n", i);
 510         else
 511                 pr_info("%d stale EC events cleared\n", i);
 512 }
 513
 514 void acpi_ec_block_transactions(void)
 515 {
 516         struct acpi_ec *ec = first_ec;
 517
 518         if (!ec)
 519                 return;
 520
 521         mutex_lock(&ec->mutex);
 522         /* Prevent transactions from being carried out */
 523         set_bit(EC_FLAGS_BLOCKED, &ec->flags);
 524         mutex_unlock(&ec->mutex);
 525 }
 526
 527 void acpi_ec_unblock_transactions(void)
 528 {
 529         struct acpi_ec *ec = first_ec;
 530
 531         if (!ec)
 532                 return;
 533
 534         mutex_lock(&ec->mutex);
 535         /* Allow transactions to be carried out again */
 536         clear_bit(EC_FLAGS_BLOCKED, &ec->flags);
 537
 538         if (EC_FLAGS_CLEAR_ON_RESUME)
 539                 acpi_ec_clear(ec);
 540
 541         mutex_unlock(&ec->mutex);
 542 }
 543
 544 void acpi_ec_unblock_transactions_early(void)
 545 {
 546         /*
 547          * Allow transactions to happen again (this function is called from
 548          * atomic context during wakeup, so we don't need to acquire the mutex).
 549          */
 550         if (first_ec)
 551                 clear_bit(EC_FLAGS_BLOCKED, &first_ec->flags);
 552 }
 553
 554 static int acpi_ec_query_unlocked(struct acpi_ec *ec, u8 *data)
 555 {
 556         int result;
 557         u8 d;
 558         struct transaction t = {.command = ACPI_EC_COMMAND_QUERY,
 559                                 .wdata = NULL, .rdata = &d,
 560                                 .wlen = 0, .rlen = 1};
 561
 562         if (!ec || !data)
 563                 return -EINVAL;
 564         /*
 565          * Query the EC to find out which _Qxx method we need to evaluate.
 566          * Note that successful completion of the query causes the ACPI_EC_SCI
 567          * bit to be cleared (and thus clearing the interrupt source).
 568          */
 569         result = acpi_ec_transaction_unlocked(ec, &t);
 570         if (result)
 571                 return result;
 572         if (!d)
 573                 return -ENODATA;
 574         *data = d;
 575         return 0;
 576 }
 577
 578 /* --------------------------------------------------------------------------
 579                                 Event Management
 580    -------------------------------------------------------------------------- */
 581 int acpi_ec_add_query_handler(struct acpi_ec *ec, u8 query_bit,
 582                               acpi_handle handle, acpi_ec_query_func func,
 583                               void *data)
 584 {
 585         struct acpi_ec_query_handler *handler =
 586             kzalloc(sizeof(struct acpi_ec_query_handler), GFP_KERNEL);
 587
 588         if (!handler)
 589                 return -ENOMEM;
 590
 591         handler->query_bit = query_bit;
 592         handler->handle = handle;
 593         handler->func = func;
 594         handler->data = data;
 595         mutex_lock(&ec->mutex);
 596         list_add(&handler->node, &ec->list);
 597         mutex_unlock(&ec->mutex);
 598         return 0;
 599 }
 600 EXPORT_SYMBOL_GPL(acpi_ec_add_query_handler);
 601
 602 void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit)
 603 {
 604         struct acpi_ec_query_handler *handler, *tmp;
 605
 606         mutex_lock(&ec->mutex);
 607         list_for_each_entry_safe(handler, tmp, &ec->list, node) {
 608                 if (query_bit == handler->query_bit) {
 609                         list_del(&handler->node);
 610                         kfree(handler);
 611                 }
 612         }
 613         mutex_unlock(&ec->mutex);
 614 }
 615 EXPORT_SYMBOL_GPL(acpi_ec_remove_query_handler);
 616
 617 static void acpi_ec_run(void *cxt)
 618 {
 619         struct acpi_ec_query_handler *handler = cxt;
 620
 621         if (!handler)
 622                 return;
 623         pr_debug("##### Query(0x%02x) started #####\n", handler->query_bit);
 624         if (handler->func)
 625                 handler->func(handler->data);
 626         else if (handler->handle)
 627                 acpi_evaluate_object(handler->handle, NULL, NULL, NULL);
 628         pr_debug("##### Query(0x%02x) stopped #####\n", handler->query_bit);
 629         kfree(handler);
 630 }
 631
 632 static int acpi_ec_sync_query(struct acpi_ec *ec, u8 *data)
 633 {
 634         u8 value = 0;
 635         int status;
 636         struct acpi_ec_query_handler *handler, *copy;
 637
 638         status = acpi_ec_query_unlocked(ec, &value);
 639         if (data)
 640                 *data = value;
 641         if (status)
 642                 return status;
 643
 644         list_for_each_entry(handler, &ec->list, node) {
 645                 if (value == handler->query_bit) {
 646                         /* have custom handler for this bit */
 647                         copy = kmalloc(sizeof(*handler), GFP_KERNEL);
 648                         if (!copy)
 649                                 return -ENOMEM;
 650                         memcpy(copy, handler, sizeof(*copy));
 651                         pr_debug("##### Query(0x%02x) scheduled #####\n",
 652                                  handler->query_bit);
 653                         return acpi_os_execute((copy->func) ?
 654                                 OSL_NOTIFY_HANDLER : OSL_GPE_HANDLER,
 655                                 acpi_ec_run, copy);
 656                 }
 657         }
 658         return 0;
 659 }
 660
 661 static void acpi_ec_gpe_query(void *ec_cxt)
 662 {
 663         struct acpi_ec *ec = ec_cxt;
 664
 665         if (!ec)
 666                 return;
 667         mutex_lock(&ec->mutex);
 668         acpi_ec_sync_query(ec, NULL);
 669         mutex_unlock(&ec->mutex);
 670 }
 671
 672 static int ec_check_sci(struct acpi_ec *ec, u8 state)
 673 {
 674         if (state & ACPI_EC_FLAG_SCI) {
 675                 if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) {
 676                         pr_debug("***** Event started *****\n");
 677                         return acpi_os_execute(OSL_NOTIFY_HANDLER,
 678                                 acpi_ec_gpe_query, ec);
 679                 }
 680         }
 681         return 0;
 682 }
 683
 684 static u32 acpi_ec_gpe_handler(acpi_handle gpe_device,
 685         u32 gpe_number, void *data)
 686 {
 687         unsigned long flags;
 688         struct acpi_ec *ec = data;
 689
 690         spin_lock_irqsave(&ec->lock, flags);
 691         if (advance_transaction(ec))
 692                 wake_up(&ec->wait);
 693         spin_unlock_irqrestore(&ec->lock, flags);
 694         ec_check_sci(ec, acpi_ec_read_status(ec));
 695         return ACPI_INTERRUPT_HANDLED | ACPI_REENABLE_GPE;
 696 }
 697
 698 /* --------------------------------------------------------------------------
 699  *                           Address Space Management
 700  * -------------------------------------------------------------------------- */
 701
 702 static acpi_status
 703 acpi_ec_space_handler(u32 function, acpi_physical_address address,
 704                       u32 bits, u64 *value64,
 705                       void *handler_context, void *region_context)
 706 {
 707         struct acpi_ec *ec = handler_context;
 708         int result = 0, i, bytes = bits / 8;
 709         u8 *value = (u8 *)value64;
 710
 711         if ((address > 0xFF) || !value || !handler_context)
 712                 return AE_BAD_PARAMETER;
 713
 714         if (function != ACPI_READ && function != ACPI_WRITE)
 715                 return AE_BAD_PARAMETER;
 716
 717         if (EC_FLAGS_MSI || bits > 8)
 718                 acpi_ec_burst_enable(ec);
 719
 720         for (i = 0; i < bytes; ++i, ++address, ++value)
 721                 result = (function == ACPI_READ) ?
 722                         acpi_ec_read(ec, address, value) :
 723                         acpi_ec_write(ec, address, *value);
 724
 725         if (EC_FLAGS_MSI || bits > 8)
 726                 acpi_ec_burst_disable(ec);
 727
 728         switch (result) {
 729         case -EINVAL:
 730                 return AE_BAD_PARAMETER;
 731         case -ENODEV:
 732                 return AE_NOT_FOUND;
 733         case -ETIME:
 734                 return AE_TIME;
 735         default:
 736                 return AE_OK;
 737         }
 738 }
 739
 740 /* --------------------------------------------------------------------------
 741  *                             Driver Interface
 742  * -------------------------------------------------------------------------- */
 743
 744 static acpi_status
 745 ec_parse_io_ports(struct acpi_resource *resource, void *context);
 746
 747 static struct acpi_ec *make_acpi_ec(void)
 748 {
 749         struct acpi_ec *ec = kzalloc(sizeof(struct acpi_ec), GFP_KERNEL);
 750
 751         if (!ec)
 752                 return NULL;
 753         ec->flags = 1 << EC_FLAGS_QUERY_PENDING;
 754         mutex_init(&ec->mutex);
 755         init_waitqueue_head(&ec->wait);
 756         INIT_LIST_HEAD(&ec->list);
 757         spin_lock_init(&ec->lock);
 758         return ec;
 759 }
 760
 761 static acpi_status
 762 acpi_ec_register_query_methods(acpi_handle handle, u32 level,
 763                                void *context, void **return_value)
 764 {
 765         char node_name[5];
 766         struct acpi_buffer buffer = { sizeof(node_name), node_name };
 767         struct acpi_ec *ec = context;
 768         int value = 0;
 769         acpi_status status;
 770
 771         status = acpi_get_name(handle, ACPI_SINGLE_NAME, &buffer);
 772
 773         if (ACPI_SUCCESS(status) && sscanf(node_name, "_Q%x", &value) == 1)
 774                 acpi_ec_add_query_handler(ec, value, handle, NULL, NULL);
 775         return AE_OK;
 776 }
 777
 778 static acpi_status
 779 ec_parse_device(acpi_handle handle, u32 Level, void *context, void **retval)
 780 {
 781         acpi_status status;
 782         unsigned long long tmp = 0;
 783         struct acpi_ec *ec = context;
 784
 785         /* clear addr values, ec_parse_io_ports depend on it */
 786         ec->command_addr = ec->data_addr = 0;
 787
 788         status = acpi_walk_resources(handle, METHOD_NAME__CRS,
 789                                      ec_parse_io_ports, ec);
 790         if (ACPI_FAILURE(status))
 791                 return status;
 792
 793         /* Get GPE bit assignment (EC events). */
 794         /* TODO: Add support for _GPE returning a package */
 795         status = acpi_evaluate_integer(handle, "_GPE", NULL, &tmp);
 796         if (ACPI_FAILURE(status))
 797                 return status;
 798         ec->gpe = tmp;
 799         /* Use the global lock for all EC transactions? */
 800         tmp = 0;
 801         acpi_evaluate_integer(handle, "_GLK", NULL, &tmp);
 802         ec->global_lock = tmp;
 803         ec->handle = handle;
 804         return AE_CTRL_TERMINATE;
 805 }
 806
 807 static int ec_install_handlers(struct acpi_ec *ec)
 808 {
 809         acpi_status status;
 810
 811         if (test_bit(EC_FLAGS_HANDLERS_INSTALLED, &ec->flags))
 812                 return 0;
 813         status = acpi_install_gpe_handler(NULL, ec->gpe,
 814                                   ACPI_GPE_EDGE_TRIGGERED,
 815                                   &acpi_ec_gpe_handler, ec);
 816         if (ACPI_FAILURE(status))
 817                 return -ENODEV;
 818
 819         acpi_enable_gpe(NULL, ec->gpe);
 820         status = acpi_install_address_space_handler(ec->handle,
 821                                                     ACPI_ADR_SPACE_EC,
 822                                                     &acpi_ec_space_handler,
 823                                                     NULL, ec);
 824         if (ACPI_FAILURE(status)) {
 825                 if (status == AE_NOT_FOUND) {
 826                         /*
 827                          * Maybe OS fails in evaluating the _REG object.
 828                          * The AE_NOT_FOUND error will be ignored and OS
 829                          * continue to initialize EC.
 830                          */
 831                         pr_err("Fail in evaluating the _REG object"
 832                                 " of EC device. Broken bios is suspected.\n");
 833                 } else {
 834                         acpi_disable_gpe(NULL, ec->gpe);
 835                         acpi_remove_gpe_handler(NULL, ec->gpe,
 836                                 &acpi_ec_gpe_handler);
 837                         return -ENODEV;
 838                 }
 839         }
 840
 841         set_bit(EC_FLAGS_HANDLERS_INSTALLED, &ec->flags);
 842         return 0;
 843 }
 844
 845 static void ec_remove_handlers(struct acpi_ec *ec)
 846 {
 847         if (!test_bit(EC_FLAGS_HANDLERS_INSTALLED, &ec->flags))
 848                 return;
 849         acpi_disable_gpe(NULL, ec->gpe);
 850         if (ACPI_FAILURE(acpi_remove_address_space_handler(ec->handle,
 851                                 ACPI_ADR_SPACE_EC, &acpi_ec_space_handler)))
 852                 pr_err("failed to remove space handler\n");
 853         if (ACPI_FAILURE(acpi_remove_gpe_handler(NULL, ec->gpe,
 854                                 &acpi_ec_gpe_handler)))
 855                 pr_err("failed to remove gpe handler\n");
 856         clear_bit(EC_FLAGS_HANDLERS_INSTALLED, &ec->flags);
 857 }
 858
 859 static int acpi_ec_add(struct acpi_device *device)
 860 {
 861         struct acpi_ec *ec = NULL;
 862         int ret;
 863
 864         strcpy(acpi_device_name(device), ACPI_EC_DEVICE_NAME);
 865         strcpy(acpi_device_class(device), ACPI_EC_CLASS);
 866
 867         /* Check for boot EC */
 868         if (boot_ec &&
 869             (boot_ec->handle == device->handle ||
 870              boot_ec->handle == ACPI_ROOT_OBJECT)) {
 871                 ec = boot_ec;
 872                 boot_ec = NULL;
 873         } else {
 874                 ec = make_acpi_ec();
 875                 if (!ec)
 876                         return -ENOMEM;
 877         }
 878         if (ec_parse_device(device->handle, 0, ec, NULL) !=
 879                 AE_CTRL_TERMINATE) {
 880                         kfree(ec);
 881                         return -EINVAL;
 882         }
 883
 884         /* Find and register all query methods */
 885         acpi_walk_namespace(ACPI_TYPE_METHOD, ec->handle, 1,
 886                             acpi_ec_register_query_methods, NULL, ec, NULL);
 887
 888         if (!first_ec)
 889                 first_ec = ec;
 890         device->driver_data = ec;
 891
 892         ret = !!request_region(ec->data_addr, 1, "EC data");
 893         WARN(!ret, "Could not request EC data io port 0x%lx", ec->data_addr);
 894         ret = !!request_region(ec->command_addr, 1, "EC cmd");
 895         WARN(!ret, "Could not request EC cmd io port 0x%lx", ec->command_addr);
 896
 897         pr_info("GPE = 0x%lx, I/O: command/status = 0x%lx, data = 0x%lx\n",
 898                           ec->gpe, ec->command_addr, ec->data_addr);
 899
 900         ret = ec_install_handlers(ec);
 901
 902         /* EC is fully operational, allow queries */
 903         clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
 904
 905         /* Clear stale _Q events if hardware might require that */
 906         if (EC_FLAGS_CLEAR_ON_RESUME) {
 907                 mutex_lock(&ec->mutex);
 908                 acpi_ec_clear(ec);
 909                 mutex_unlock(&ec->mutex);
 910         }
 911         return ret;
 912 }
 913
 914 static int acpi_ec_remove(struct acpi_device *device)
 915 {
 916         struct acpi_ec *ec;
 917         struct acpi_ec_query_handler *handler, *tmp;
 918
 919         if (!device)
 920                 return -EINVAL;
 921
 922         ec = acpi_driver_data(device);
 923         ec_remove_handlers(ec);
 924         mutex_lock(&ec->mutex);
 925         list_for_each_entry_safe(handler, tmp, &ec->list, node) {
 926                 list_del(&handler->node);
 927                 kfree(handler);
 928         }
 929         mutex_unlock(&ec->mutex);
 930         release_region(ec->data_addr, 1);
 931         release_region(ec->command_addr, 1);
 932         device->driver_data = NULL;
 933         if (ec == first_ec)
 934                 first_ec = NULL;
 935         kfree(ec);
 936         return 0;
 937 }
 938
 939 static acpi_status
 940 ec_parse_io_ports(struct acpi_resource *resource, void *context)
 941 {
 942         struct acpi_ec *ec = context;
 943
 944         if (resource->type != ACPI_RESOURCE_TYPE_IO)
 945                 return AE_OK;
 946
 947         /*
 948          * The first address region returned is the data port, and
 949          * the second address region returned is the status/command
 950          * port.
 951          */
 952         if (ec->data_addr == 0)
 953                 ec->data_addr = resource->data.io.minimum;
 954         else if (ec->command_addr == 0)
 955                 ec->command_addr = resource->data.io.minimum;
 956         else
 957                 return AE_CTRL_TERMINATE;
 958
 959         return AE_OK;
 960 }
 961
 962 int __init acpi_boot_ec_enable(void)
 963 {
 964         if (!boot_ec || test_bit(EC_FLAGS_HANDLERS_INSTALLED, &boot_ec->flags))
 965                 return 0;
 966         if (!ec_install_handlers(boot_ec)) {
 967                 first_ec = boot_ec;
 968                 return 0;
 969         }
 970         return -EFAULT;
 971 }
 972
 973 static const struct acpi_device_id ec_device_ids[] = {
 974         {"PNP0C09", 0},
 975         {"", 0},
 976 };
 977
 978 /* Some BIOS do not survive early DSDT scan, skip it */
 979 static int ec_skip_dsdt_scan(const struct dmi_system_id *id)
 980 {
 981         EC_FLAGS_SKIP_DSDT_SCAN = 1;
 982         return 0;
 983 }
 984
 985 /* ASUStek often supplies us with broken ECDT, validate it */
 986 static int ec_validate_ecdt(const struct dmi_system_id *id)
 987 {
 988         EC_FLAGS_VALIDATE_ECDT = 1;
 989         return 0;
 990 }
 991
 992 /* MSI EC needs special treatment, enable it */
 993 static int ec_flag_msi(const struct dmi_system_id *id)
 994 {
 995         pr_debug("Detected MSI hardware, enabling workarounds.\n");
 996         EC_FLAGS_MSI = 1;
 997         EC_FLAGS_VALIDATE_ECDT = 1;
 998         return 0;
 999 }
1000
1001 /*
1002  * Clevo M720 notebook actually works ok with IRQ mode, if we lifted
1003  * the GPE storm threshold back to 20
1004  */
1005 static int ec_enlarge_storm_threshold(const struct dmi_system_id *id)
1006 {
1007         pr_debug("Setting the EC GPE storm threshold to 20\n");
1008         ec_storm_threshold  = 20;
1009         return 0;
1010 }
1011
1012 /*
1013  * Acer EC firmware refuses to respond QR_EC when SCI_EVT is not set, for
1014  * which case, we complete the QR_EC without issuing it to the firmware.
1015  * https://bugzilla.kernel.org/show_bug.cgi?id=86211
1016  */
1017 static int ec_flag_query_handshake(const struct dmi_system_id *id)
1018 {
1019         pr_debug("Detected the EC firmware requiring QR_EC issued when SCI_EVT set\n");
1020         EC_FLAGS_QUERY_HANDSHAKE = 1;
1021         return 0;
1022 }
1023
1024 /*
1025  * On some hardware it is necessary to clear events accumulated by the EC during
1026  * sleep. These ECs stop reporting GPEs until they are manually polled, if too
1027  * many events are accumulated. (e.g. Samsung Series 5/9 notebooks)
1028  *
1029  * https://bugzilla.kernel.org/show_bug.cgi?id=44161
1030  *
1031  * Ideally, the EC should also be instructed NOT to accumulate events during
1032  * sleep (which Windows seems to do somehow), but the interface to control this
1033  * behaviour is not known at this time.
1034  *
1035  * Models known to be affected are Samsung 530Uxx/535Uxx/540Uxx/550Pxx/900Xxx,
1036  * however it is very likely that other Samsung models are affected.
1037  *
1038  * On systems which don't accumulate _Q events during sleep, this extra check
1039  * should be harmless.
1040  */
1041 static int ec_clear_on_resume(const struct dmi_system_id *id)
1042 {
1043         pr_debug("Detected system needing EC poll on resume.\n");
1044         EC_FLAGS_CLEAR_ON_RESUME = 1;
1045         return 0;
1046 }
1047
1048 static struct dmi_system_id ec_dmi_table[] __initdata = {
1049         {
1050         ec_skip_dsdt_scan, "Compal JFL92", {
1051         DMI_MATCH(DMI_BIOS_VENDOR, "COMPAL"),
1052         DMI_MATCH(DMI_BOARD_NAME, "JFL92") }, NULL},
1053         {
1054         ec_flag_msi, "MSI hardware", {
1055         DMI_MATCH(DMI_BIOS_VENDOR, "Micro-Star")}, NULL},
1056         {
1057         ec_flag_msi, "MSI hardware", {
1058         DMI_MATCH(DMI_SYS_VENDOR, "Micro-Star")}, NULL},
1059         {
1060         ec_flag_msi, "MSI hardware", {
1061         DMI_MATCH(DMI_CHASSIS_VENDOR, "MICRO-Star")}, NULL},
1062         {
1063         ec_flag_msi, "MSI hardware", {
1064         DMI_MATCH(DMI_CHASSIS_VENDOR, "MICRO-STAR")}, NULL},
1065         {
1066         ec_flag_msi, "Quanta hardware", {
1067         DMI_MATCH(DMI_SYS_VENDOR, "Quanta"),
1068         DMI_MATCH(DMI_PRODUCT_NAME, "TW8/SW8/DW8"),}, NULL},
1069         {
1070         ec_flag_msi, "Quanta hardware", {
1071         DMI_MATCH(DMI_SYS_VENDOR, "Quanta"),
1072         DMI_MATCH(DMI_PRODUCT_NAME, "TW9/SW9"),}, NULL},
1073         {
1074         ec_flag_msi, "Clevo W350etq", {
1075         DMI_MATCH(DMI_SYS_VENDOR, "CLEVO CO."),
1076         DMI_MATCH(DMI_PRODUCT_NAME, "W35_37ET"),}, NULL},
1077         {
1078         ec_validate_ecdt, "ASUS hardware", {
1079         DMI_MATCH(DMI_BIOS_VENDOR, "ASUS") }, NULL},
1080         {
1081         ec_validate_ecdt, "ASUS hardware", {
1082         DMI_MATCH(DMI_BOARD_VENDOR, "ASUSTeK Computer Inc.") }, NULL},
1083         {
1084         ec_enlarge_storm_threshold, "CLEVO hardware", {
1085         DMI_MATCH(DMI_SYS_VENDOR, "CLEVO Co."),
1086         DMI_MATCH(DMI_PRODUCT_NAME, "M720T/M730T"),}, NULL},
1087         {
1088         ec_skip_dsdt_scan, "HP Folio 13", {
1089         DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
1090         DMI_MATCH(DMI_PRODUCT_NAME, "HP Folio 13"),}, NULL},
1091         {
1092         ec_validate_ecdt, "ASUS hardware", {
1093         DMI_MATCH(DMI_SYS_VENDOR, "ASUSTek Computer Inc."),
1094         DMI_MATCH(DMI_PRODUCT_NAME, "L4R"),}, NULL},
1095         {
1096         ec_clear_on_resume, "Samsung hardware", {
1097         DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD.")}, NULL},
1098         {
1099         ec_flag_query_handshake, "Acer hardware", {
1100         DMI_MATCH(DMI_SYS_VENDOR, "Acer"), }, NULL},
1101         {},
1102 };
1103
1104 int __init acpi_ec_ecdt_probe(void)
1105 {
1106         acpi_status status;
1107         struct acpi_ec *saved_ec = NULL;
1108         struct acpi_table_ecdt *ecdt_ptr;
1109
1110         boot_ec = make_acpi_ec();
1111         if (!boot_ec)
1112                 return -ENOMEM;
1113         /*
1114          * Generate a boot ec context
1115          */
1116         dmi_check_system(ec_dmi_table);
1117         status = acpi_get_table(ACPI_SIG_ECDT, 1,
1118                                 (struct acpi_table_header **)&ecdt_ptr);
1119         if (ACPI_SUCCESS(status)) {
1120                 pr_info("EC description table is found, configuring boot EC\n");
1121                 boot_ec->command_addr = ecdt_ptr->control.address;
1122                 boot_ec->data_addr = ecdt_ptr->data.address;
1123                 boot_ec->gpe = ecdt_ptr->gpe;
1124                 boot_ec->handle = ACPI_ROOT_OBJECT;
1125                 acpi_get_handle(ACPI_ROOT_OBJECT, ecdt_ptr->id,
1126                                 &boot_ec->handle);
1127                 /* Don't trust ECDT, which comes from ASUSTek */
1128                 if (!EC_FLAGS_VALIDATE_ECDT)
1129                         goto install;
1130                 saved_ec = kmemdup(boot_ec, sizeof(struct acpi_ec), GFP_KERNEL);
1131                 if (!saved_ec)
1132                         return -ENOMEM;
1133         /* fall through */
1134         }
1135
1136         if (EC_FLAGS_SKIP_DSDT_SCAN) {
1137                 kfree(saved_ec);
1138                 return -ENODEV;
1139         }
1140
1141         /* This workaround is needed only on some broken machines,
1142          * which require early EC, but fail to provide ECDT */
1143         pr_debug("Look up EC in DSDT\n");
1144         status = acpi_get_devices(ec_device_ids[0].id, ec_parse_device,
1145                                         boot_ec, NULL);
1146         /* Check that acpi_get_devices actually find something */
1147         if (ACPI_FAILURE(status) || !boot_ec->handle)
1148                 goto error;
1149         if (saved_ec) {
1150                 /* try to find good ECDT from ASUSTek */
1151                 if (saved_ec->command_addr != boot_ec->command_addr ||
1152                     saved_ec->data_addr != boot_ec->data_addr ||
1153                     saved_ec->gpe != boot_ec->gpe ||
1154                     saved_ec->handle != boot_ec->handle)
1155                         pr_info("ASUSTek keeps feeding us with broken "
1156                         "ECDT tables, which are very hard to workaround. "
1157                         "Trying to use DSDT EC info instead. Please send "
1158                         "output of acpidump to linux-acpi@vger.kernel.org\n");
1159                 kfree(saved_ec);
1160                 saved_ec = NULL;
1161         } else {
1162                 /* We really need to limit this workaround, the only ASUS,
1163                 * which needs it, has fake EC._INI method, so use it as flag.
1164                 * Keep boot_ec struct as it will be needed soon.
1165                 */
1166                 if (!dmi_name_in_vendors("ASUS") ||
1167                     !acpi_has_method(boot_ec->handle, "_INI"))
1168                         return -ENODEV;
1169         }
1170 install:
1171         if (!ec_install_handlers(boot_ec)) {
1172                 first_ec = boot_ec;
1173                 return 0;
1174         }
1175 error:
1176         kfree(boot_ec);
1177         kfree(saved_ec);
1178         boot_ec = NULL;
1179         return -ENODEV;
1180 }
1181
1182 static struct acpi_driver acpi_ec_driver = {
1183         .name = "ec",
1184         .class = ACPI_EC_CLASS,
1185         .ids = ec_device_ids,
1186         .ops = {
1187                 .add = acpi_ec_add,
1188                 .remove = acpi_ec_remove,
1189                 },
1190 };
1191
1192 int __init acpi_ec_init(void)
1193 {
1194         int result = 0;
1195
1196         /* Now register the driver for the EC */
1197         result = acpi_bus_register_driver(&acpi_ec_driver);
1198         if (result < 0)
1199                 return -ENODEV;
1200
1201         return result;
1202 }
1203
1204 /* EC driver currently not unloadable */
1205 #if 0
1206 static void __exit acpi_ec_exit(void)
1207 {
1208
1209         acpi_bus_unregister_driver(&acpi_ec_driver);
1210 }
1211 #endif  /* 0 */