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