git.oblomov.eu Git - linux-2.6/blob - drivers/acpi/acpica/evgpe.c

   1 /******************************************************************************
   2  *
   3  * Module Name: evgpe - General Purpose Event handling and dispatch
   4  *
   5  *****************************************************************************/
   6
   7 /*
   8  * Copyright (C) 2000 - 2008, Intel Corp.
   9  * All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions, and the following disclaimer,
  16  *    without modification.
  17  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
  18  *    substantially similar to the "NO WARRANTY" disclaimer below
  19  *    ("Disclaimer") and any redistribution must be conditioned upon
  20  *    including a substantially similar Disclaimer requirement for further
  21  *    binary redistribution.
  22  * 3. Neither the names of the above-listed copyright holders nor the names
  23  *    of any contributors may be used to endorse or promote products derived
  24  *    from this software without specific prior written permission.
  25  *
  26  * Alternatively, this software may be distributed under the terms of the
  27  * GNU General Public License ("GPL") version 2 as published by the Free
  28  * Software Foundation.
  29  *
  30  * NO WARRANTY
  31  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  32  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  33  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
  34  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  35  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  36  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  37  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  39  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  40  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  41  * POSSIBILITY OF SUCH DAMAGES.
  42  */
  43
  44 #include <acpi/acpi.h>
  45 #include "accommon.h"
  46 #include "acevents.h"
  47 #include "acnamesp.h"
  48
  49 #define _COMPONENT          ACPI_EVENTS
  50 ACPI_MODULE_NAME("evgpe")
  51
  52 /* Local prototypes */
  53 static void ACPI_SYSTEM_XFACE acpi_ev_asynch_execute_gpe_method(void *context);
  54
  55 /*******************************************************************************
  56  *
  57  * FUNCTION:    acpi_ev_set_gpe_type
  58  *
  59  * PARAMETERS:  gpe_event_info          - GPE to set
  60  *              Type                    - New type
  61  *
  62  * RETURN:      Status
  63  *
  64  * DESCRIPTION: Sets the new type for the GPE (wake, run, or wake/run)
  65  *
  66  ******************************************************************************/
  67
  68 acpi_status
  69 acpi_ev_set_gpe_type(struct acpi_gpe_event_info *gpe_event_info, u8 type)
  70 {
  71         acpi_status status;
  72
  73         ACPI_FUNCTION_TRACE(ev_set_gpe_type);
  74
  75         /* Validate type and update register enable masks */
  76
  77         switch (type) {
  78         case ACPI_GPE_TYPE_WAKE:
  79         case ACPI_GPE_TYPE_RUNTIME:
  80         case ACPI_GPE_TYPE_WAKE_RUN:
  81                 break;
  82
  83         default:
  84                 return_ACPI_STATUS(AE_BAD_PARAMETER);
  85         }
  86
  87         /* Disable the GPE if currently enabled */
  88
  89         status = acpi_ev_disable_gpe(gpe_event_info);
  90
  91         /* Clear the type bits and insert the new Type */
  92
  93         gpe_event_info->flags &= ~ACPI_GPE_TYPE_MASK;
  94         gpe_event_info->flags |= type;
  95         return_ACPI_STATUS(status);
  96 }
  97
  98 /*******************************************************************************
  99  *
 100  * FUNCTION:    acpi_ev_update_gpe_enable_masks
 101  *
 102  * PARAMETERS:  gpe_event_info          - GPE to update
 103  *              Type                    - What to do: ACPI_GPE_DISABLE or
 104  *                                        ACPI_GPE_ENABLE
 105  *
 106  * RETURN:      Status
 107  *
 108  * DESCRIPTION: Updates GPE register enable masks based on the GPE type
 109  *
 110  ******************************************************************************/
 111
 112 acpi_status
 113 acpi_ev_update_gpe_enable_masks(struct acpi_gpe_event_info *gpe_event_info,
 114                                 u8 type)
 115 {
 116         struct acpi_gpe_register_info *gpe_register_info;
 117         u8 register_bit;
 118
 119         ACPI_FUNCTION_TRACE(ev_update_gpe_enable_masks);
 120
 121         gpe_register_info = gpe_event_info->register_info;
 122         if (!gpe_register_info) {
 123                 return_ACPI_STATUS(AE_NOT_EXIST);
 124         }
 125
 126         register_bit = (u8)
 127             (1 <<
 128              (gpe_event_info->gpe_number - gpe_register_info->base_gpe_number));
 129
 130         /* 1) Disable case. Simply clear all enable bits */
 131
 132         if (type == ACPI_GPE_DISABLE) {
 133                 ACPI_CLEAR_BIT(gpe_register_info->enable_for_wake,
 134                                register_bit);
 135                 ACPI_CLEAR_BIT(gpe_register_info->enable_for_run, register_bit);
 136                 return_ACPI_STATUS(AE_OK);
 137         }
 138
 139         /* 2) Enable case. Set/Clear the appropriate enable bits */
 140
 141         switch (gpe_event_info->flags & ACPI_GPE_TYPE_MASK) {
 142         case ACPI_GPE_TYPE_WAKE:
 143                 ACPI_SET_BIT(gpe_register_info->enable_for_wake, register_bit);
 144                 ACPI_CLEAR_BIT(gpe_register_info->enable_for_run, register_bit);
 145                 break;
 146
 147         case ACPI_GPE_TYPE_RUNTIME:
 148                 ACPI_CLEAR_BIT(gpe_register_info->enable_for_wake,
 149                                register_bit);
 150                 ACPI_SET_BIT(gpe_register_info->enable_for_run, register_bit);
 151                 break;
 152
 153         case ACPI_GPE_TYPE_WAKE_RUN:
 154                 ACPI_SET_BIT(gpe_register_info->enable_for_wake, register_bit);
 155                 ACPI_SET_BIT(gpe_register_info->enable_for_run, register_bit);
 156                 break;
 157
 158         default:
 159                 return_ACPI_STATUS(AE_BAD_PARAMETER);
 160         }
 161
 162         return_ACPI_STATUS(AE_OK);
 163 }
 164
 165 /*******************************************************************************
 166  *
 167  * FUNCTION:    acpi_ev_enable_gpe
 168  *
 169  * PARAMETERS:  gpe_event_info          - GPE to enable
 170  *              write_to_hardware       - Enable now, or just mark data structs
 171  *                                        (WAKE GPEs should be deferred)
 172  *
 173  * RETURN:      Status
 174  *
 175  * DESCRIPTION: Enable a GPE based on the GPE type
 176  *
 177  ******************************************************************************/
 178
 179 acpi_status
 180 acpi_ev_enable_gpe(struct acpi_gpe_event_info *gpe_event_info,
 181                    u8 write_to_hardware)
 182 {
 183         acpi_status status;
 184
 185         ACPI_FUNCTION_TRACE(ev_enable_gpe);
 186
 187         /* Make sure HW enable masks are updated */
 188
 189         status =
 190             acpi_ev_update_gpe_enable_masks(gpe_event_info, ACPI_GPE_ENABLE);
 191         if (ACPI_FAILURE(status)) {
 192                 return_ACPI_STATUS(status);
 193         }
 194
 195         /* Mark wake-enabled or HW enable, or both */
 196
 197         switch (gpe_event_info->flags & ACPI_GPE_TYPE_MASK) {
 198         case ACPI_GPE_TYPE_WAKE:
 199
 200                 ACPI_SET_BIT(gpe_event_info->flags, ACPI_GPE_WAKE_ENABLED);
 201                 break;
 202
 203         case ACPI_GPE_TYPE_WAKE_RUN:
 204
 205                 ACPI_SET_BIT(gpe_event_info->flags, ACPI_GPE_WAKE_ENABLED);
 206
 207                 /*lint -fallthrough */
 208
 209         case ACPI_GPE_TYPE_RUNTIME:
 210
 211                 ACPI_SET_BIT(gpe_event_info->flags, ACPI_GPE_RUN_ENABLED);
 212
 213                 if (write_to_hardware) {
 214
 215                         /* Clear the GPE (of stale events), then enable it */
 216
 217                         status = acpi_hw_clear_gpe(gpe_event_info);
 218                         if (ACPI_FAILURE(status)) {
 219                                 return_ACPI_STATUS(status);
 220                         }
 221
 222                         /* Enable the requested runtime GPE */
 223
 224                         status = acpi_hw_write_gpe_enable_reg(gpe_event_info);
 225                 }
 226                 break;
 227
 228         default:
 229                 return_ACPI_STATUS(AE_BAD_PARAMETER);
 230         }
 231
 232         return_ACPI_STATUS(AE_OK);
 233 }
 234
 235 /*******************************************************************************
 236  *
 237  * FUNCTION:    acpi_ev_disable_gpe
 238  *
 239  * PARAMETERS:  gpe_event_info          - GPE to disable
 240  *
 241  * RETURN:      Status
 242  *
 243  * DESCRIPTION: Disable a GPE based on the GPE type
 244  *
 245  ******************************************************************************/
 246
 247 acpi_status acpi_ev_disable_gpe(struct acpi_gpe_event_info *gpe_event_info)
 248 {
 249         acpi_status status;
 250
 251         ACPI_FUNCTION_TRACE(ev_disable_gpe);
 252
 253         /* Make sure HW enable masks are updated */
 254
 255         status =
 256             acpi_ev_update_gpe_enable_masks(gpe_event_info, ACPI_GPE_DISABLE);
 257         if (ACPI_FAILURE(status)) {
 258                 return_ACPI_STATUS(status);
 259         }
 260
 261         /* Clear the appropriate enabled flags for this GPE */
 262
 263         switch (gpe_event_info->flags & ACPI_GPE_TYPE_MASK) {
 264         case ACPI_GPE_TYPE_WAKE:
 265                 ACPI_CLEAR_BIT(gpe_event_info->flags, ACPI_GPE_WAKE_ENABLED);
 266                 break;
 267
 268         case ACPI_GPE_TYPE_WAKE_RUN:
 269                 ACPI_CLEAR_BIT(gpe_event_info->flags, ACPI_GPE_WAKE_ENABLED);
 270
 271                 /* fallthrough */
 272
 273         case ACPI_GPE_TYPE_RUNTIME:
 274
 275                 /* Disable the requested runtime GPE */
 276
 277                 ACPI_CLEAR_BIT(gpe_event_info->flags, ACPI_GPE_RUN_ENABLED);
 278                 break;
 279
 280         default:
 281                 break;
 282         }
 283
 284         /*
 285          * Even if we don't know the GPE type, make sure that we always
 286          * disable it. low_disable_gpe will just clear the enable bit for this
 287          * GPE and write it. It will not write out the current GPE enable mask,
 288          * since this may inadvertently enable GPEs too early, if a rogue GPE has
 289          * come in during ACPICA initialization - possibly as a result of AML or
 290          * other code that has enabled the GPE.
 291          */
 292         status = acpi_hw_low_disable_gpe(gpe_event_info);
 293         return_ACPI_STATUS(status);
 294 }
 295
 296 /*******************************************************************************
 297  *
 298  * FUNCTION:    acpi_ev_get_gpe_event_info
 299  *
 300  * PARAMETERS:  gpe_device          - Device node. NULL for GPE0/GPE1
 301  *              gpe_number          - Raw GPE number
 302  *
 303  * RETURN:      A GPE event_info struct. NULL if not a valid GPE
 304  *
 305  * DESCRIPTION: Returns the event_info struct associated with this GPE.
 306  *              Validates the gpe_block and the gpe_number
 307  *
 308  *              Should be called only when the GPE lists are semaphore locked
 309  *              and not subject to change.
 310  *
 311  ******************************************************************************/
 312
 313 struct acpi_gpe_event_info *acpi_ev_get_gpe_event_info(acpi_handle gpe_device,
 314                                                        u32 gpe_number)
 315 {
 316         union acpi_operand_object *obj_desc;
 317         struct acpi_gpe_block_info *gpe_block;
 318         u32 i;
 319
 320         ACPI_FUNCTION_ENTRY();
 321
 322         /* A NULL gpe_block means use the FADT-defined GPE block(s) */
 323
 324         if (!gpe_device) {
 325
 326                 /* Examine GPE Block 0 and 1 (These blocks are permanent) */
 327
 328                 for (i = 0; i < ACPI_MAX_GPE_BLOCKS; i++) {
 329                         gpe_block = acpi_gbl_gpe_fadt_blocks[i];
 330                         if (gpe_block) {
 331                                 if ((gpe_number >= gpe_block->block_base_number)
 332                                     && (gpe_number <
 333                                         gpe_block->block_base_number +
 334                                         (gpe_block->register_count * 8))) {
 335                                         return (&gpe_block->
 336                                                 event_info[gpe_number -
 337                                                            gpe_block->
 338                                                            block_base_number]);
 339                                 }
 340                         }
 341                 }
 342
 343                 /* The gpe_number was not in the range of either FADT GPE block */
 344
 345                 return (NULL);
 346         }
 347
 348         /* A Non-NULL gpe_device means this is a GPE Block Device */
 349
 350         obj_desc = acpi_ns_get_attached_object((struct acpi_namespace_node *)
 351                                                gpe_device);
 352         if (!obj_desc || !obj_desc->device.gpe_block) {
 353                 return (NULL);
 354         }
 355
 356         gpe_block = obj_desc->device.gpe_block;
 357
 358         if ((gpe_number >= gpe_block->block_base_number) &&
 359             (gpe_number <
 360              gpe_block->block_base_number + (gpe_block->register_count * 8))) {
 361                 return (&gpe_block->
 362                         event_info[gpe_number - gpe_block->block_base_number]);
 363         }
 364
 365         return (NULL);
 366 }
 367
 368 /*******************************************************************************
 369  *
 370  * FUNCTION:    acpi_ev_gpe_detect
 371  *
 372  * PARAMETERS:  gpe_xrupt_list      - Interrupt block for this interrupt.
 373  *                                    Can have multiple GPE blocks attached.
 374  *
 375  * RETURN:      INTERRUPT_HANDLED or INTERRUPT_NOT_HANDLED
 376  *
 377  * DESCRIPTION: Detect if any GP events have occurred. This function is
 378  *              executed at interrupt level.
 379  *
 380  ******************************************************************************/
 381
 382 u32 acpi_ev_gpe_detect(struct acpi_gpe_xrupt_info * gpe_xrupt_list)
 383 {
 384         acpi_status status;
 385         struct acpi_gpe_block_info *gpe_block;
 386         struct acpi_gpe_register_info *gpe_register_info;
 387         u32 int_status = ACPI_INTERRUPT_NOT_HANDLED;
 388         u8 enabled_status_byte;
 389         u32 status_reg;
 390         u32 enable_reg;
 391         acpi_cpu_flags flags;
 392         u32 i;
 393         u32 j;
 394
 395         ACPI_FUNCTION_NAME(ev_gpe_detect);
 396
 397         /* Check for the case where there are no GPEs */
 398
 399         if (!gpe_xrupt_list) {
 400                 return (int_status);
 401         }
 402
 403         /*
 404          * We need to obtain the GPE lock for both the data structs and registers
 405          * Note: Not necessary to obtain the hardware lock, since the GPE
 406          * registers are owned by the gpe_lock.
 407          */
 408         flags = acpi_os_acquire_lock(acpi_gbl_gpe_lock);
 409
 410         /* Examine all GPE blocks attached to this interrupt level */
 411
 412         gpe_block = gpe_xrupt_list->gpe_block_list_head;
 413         while (gpe_block) {
 414                 /*
 415                  * Read all of the 8-bit GPE status and enable registers in this GPE
 416                  * block, saving all of them. Find all currently active GP events.
 417                  */
 418                 for (i = 0; i < gpe_block->register_count; i++) {
 419
 420                         /* Get the next status/enable pair */
 421
 422                         gpe_register_info = &gpe_block->register_info[i];
 423
 424                         /* Read the Status Register */
 425
 426                         status =
 427                             acpi_read(&status_reg,
 428                                       &gpe_register_info->status_address);
 429                         if (ACPI_FAILURE(status)) {
 430                                 goto unlock_and_exit;
 431                         }
 432
 433                         /* Read the Enable Register */
 434
 435                         status =
 436                             acpi_read(&enable_reg,
 437                                       &gpe_register_info->enable_address);
 438                         if (ACPI_FAILURE(status)) {
 439                                 goto unlock_and_exit;
 440                         }
 441
 442                         ACPI_DEBUG_PRINT((ACPI_DB_INTERRUPTS,
 443                                           "Read GPE Register at GPE%X: Status=%02X, Enable=%02X\n",
 444                                           gpe_register_info->base_gpe_number,
 445                                           status_reg, enable_reg));
 446
 447                         /* Check if there is anything active at all in this register */
 448
 449                         enabled_status_byte = (u8) (status_reg & enable_reg);
 450                         if (!enabled_status_byte) {
 451
 452                                 /* No active GPEs in this register, move on */
 453
 454                                 continue;
 455                         }
 456
 457                         /* Now look at the individual GPEs in this byte register */
 458
 459                         for (j = 0; j < ACPI_GPE_REGISTER_WIDTH; j++) {
 460
 461                                 /* Examine one GPE bit */
 462
 463                                 if (enabled_status_byte & (1 << j)) {
 464                                         /*
 465                                          * Found an active GPE. Dispatch the event to a handler
 466                                          * or method.
 467                                          */
 468                                         int_status |=
 469                                             acpi_ev_gpe_dispatch(&gpe_block->
 470                                                 event_info[((acpi_size) i * ACPI_GPE_REGISTER_WIDTH) + j], j + gpe_register_info->base_gpe_number);
 471                                 }
 472                         }
 473                 }
 474
 475                 gpe_block = gpe_block->next;
 476         }
 477
 478       unlock_and_exit:
 479
 480         acpi_os_release_lock(acpi_gbl_gpe_lock, flags);
 481         return (int_status);
 482 }
 483
 484 /*******************************************************************************
 485  *
 486  * FUNCTION:    acpi_ev_asynch_execute_gpe_method
 487  *
 488  * PARAMETERS:  Context (gpe_event_info) - Info for this GPE
 489  *
 490  * RETURN:      None
 491  *
 492  * DESCRIPTION: Perform the actual execution of a GPE control method. This
 493  *              function is called from an invocation of acpi_os_execute and
 494  *              therefore does NOT execute at interrupt level - so that
 495  *              the control method itself is not executed in the context of
 496  *              an interrupt handler.
 497  *
 498  ******************************************************************************/
 499 static void acpi_ev_asynch_enable_gpe(void *context);
 500
 501 static void ACPI_SYSTEM_XFACE acpi_ev_asynch_execute_gpe_method(void *context)
 502 {
 503         struct acpi_gpe_event_info *gpe_event_info = (void *)context;
 504         acpi_status status;
 505         struct acpi_gpe_event_info local_gpe_event_info;
 506         struct acpi_evaluate_info *info;
 507
 508         ACPI_FUNCTION_TRACE(ev_asynch_execute_gpe_method);
 509
 510         status = acpi_ut_acquire_mutex(ACPI_MTX_EVENTS);
 511         if (ACPI_FAILURE(status)) {
 512                 return_VOID;
 513         }
 514
 515         /* Must revalidate the gpe_number/gpe_block */
 516
 517         if (!acpi_ev_valid_gpe_event(gpe_event_info)) {
 518                 status = acpi_ut_release_mutex(ACPI_MTX_EVENTS);
 519                 return_VOID;
 520         }
 521
 522         /* Set the GPE flags for return to enabled state */
 523
 524         (void)acpi_ev_enable_gpe(gpe_event_info, FALSE);
 525
 526         /*
 527          * Take a snapshot of the GPE info for this level - we copy the info to
 528          * prevent a race condition with remove_handler/remove_block.
 529          */
 530         ACPI_MEMCPY(&local_gpe_event_info, gpe_event_info,
 531                     sizeof(struct acpi_gpe_event_info));
 532
 533         status = acpi_ut_release_mutex(ACPI_MTX_EVENTS);
 534         if (ACPI_FAILURE(status)) {
 535                 return_VOID;
 536         }
 537
 538         /*
 539          * Must check for control method type dispatch one more time to avoid a
 540          * race with ev_gpe_install_handler
 541          */
 542         if ((local_gpe_event_info.flags & ACPI_GPE_DISPATCH_MASK) ==
 543             ACPI_GPE_DISPATCH_METHOD) {
 544
 545                 /* Allocate the evaluation information block */
 546
 547                 info = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_evaluate_info));
 548                 if (!info) {
 549                         status = AE_NO_MEMORY;
 550                 } else {
 551                         /*
 552                          * Invoke the GPE Method (_Lxx, _Exx) i.e., evaluate the _Lxx/_Exx
 553                          * control method that corresponds to this GPE
 554                          */
 555                         info->prefix_node =
 556                             local_gpe_event_info.dispatch.method_node;
 557                         info->flags = ACPI_IGNORE_RETURN_VALUE;
 558
 559                         status = acpi_ns_evaluate(info);
 560                         ACPI_FREE(info);
 561                 }
 562
 563                 if (ACPI_FAILURE(status)) {
 564                         ACPI_EXCEPTION((AE_INFO, status,
 565                                         "while evaluating GPE method [%4.4s]",
 566                                         acpi_ut_get_node_name
 567                                         (local_gpe_event_info.dispatch.
 568                                          method_node)));
 569                 }
 570         }
 571         /* Defer enabling of GPE until all notify handlers are done */
 572         acpi_os_execute(OSL_NOTIFY_HANDLER, acpi_ev_asynch_enable_gpe,
 573                                 gpe_event_info);
 574         return_VOID;
 575 }
 576
 577 static void acpi_ev_asynch_enable_gpe(void *context)
 578 {
 579         struct acpi_gpe_event_info *gpe_event_info = context;
 580         acpi_status status;
 581         if ((gpe_event_info->flags & ACPI_GPE_XRUPT_TYPE_MASK) ==
 582             ACPI_GPE_LEVEL_TRIGGERED) {
 583                 /*
 584                  * GPE is level-triggered, we clear the GPE status bit after handling
 585                  * the event.
 586                  */
 587                 status = acpi_hw_clear_gpe(gpe_event_info);
 588                 if (ACPI_FAILURE(status)) {
 589                         return_VOID;
 590                 }
 591         }
 592
 593         /* Enable this GPE */
 594         (void)acpi_hw_write_gpe_enable_reg(gpe_event_info);
 595         return_VOID;
 596 }
 597
 598 /*******************************************************************************
 599  *
 600  * FUNCTION:    acpi_ev_gpe_dispatch
 601  *
 602  * PARAMETERS:  gpe_event_info  - Info for this GPE
 603  *              gpe_number      - Number relative to the parent GPE block
 604  *
 605  * RETURN:      INTERRUPT_HANDLED or INTERRUPT_NOT_HANDLED
 606  *
 607  * DESCRIPTION: Dispatch a General Purpose Event to either a function (e.g. EC)
 608  *              or method (e.g. _Lxx/_Exx) handler.
 609  *
 610  *              This function executes at interrupt level.
 611  *
 612  ******************************************************************************/
 613
 614 u32
 615 acpi_ev_gpe_dispatch(struct acpi_gpe_event_info *gpe_event_info, u32 gpe_number)
 616 {
 617         acpi_status status;
 618
 619         ACPI_FUNCTION_TRACE(ev_gpe_dispatch);
 620
 621         acpi_os_gpe_count(gpe_number);
 622
 623         /*
 624          * If edge-triggered, clear the GPE status bit now. Note that
 625          * level-triggered events are cleared after the GPE is serviced.
 626          */
 627         if ((gpe_event_info->flags & ACPI_GPE_XRUPT_TYPE_MASK) ==
 628             ACPI_GPE_EDGE_TRIGGERED) {
 629                 status = acpi_hw_clear_gpe(gpe_event_info);
 630                 if (ACPI_FAILURE(status)) {
 631                         ACPI_EXCEPTION((AE_INFO, status,
 632                                         "Unable to clear GPE[%2X]",
 633                                         gpe_number));
 634                         return_UINT32(ACPI_INTERRUPT_NOT_HANDLED);
 635                 }
 636         }
 637
 638         /*
 639          * Dispatch the GPE to either an installed handler, or the control method
 640          * associated with this GPE (_Lxx or _Exx). If a handler exists, we invoke
 641          * it and do not attempt to run the method. If there is neither a handler
 642          * nor a method, we disable this GPE to prevent further such pointless
 643          * events from firing.
 644          */
 645         switch (gpe_event_info->flags & ACPI_GPE_DISPATCH_MASK) {
 646         case ACPI_GPE_DISPATCH_HANDLER:
 647
 648                 /*
 649                  * Invoke the installed handler (at interrupt level)
 650                  * Ignore return status for now.
 651                  * TBD: leave GPE disabled on error?
 652                  */
 653                 (void)gpe_event_info->dispatch.handler->address(gpe_event_info->
 654                                                                 dispatch.
 655                                                                 handler->
 656                                                                 context);
 657
 658                 /* It is now safe to clear level-triggered events. */
 659
 660                 if ((gpe_event_info->flags & ACPI_GPE_XRUPT_TYPE_MASK) ==
 661                     ACPI_GPE_LEVEL_TRIGGERED) {
 662                         status = acpi_hw_clear_gpe(gpe_event_info);
 663                         if (ACPI_FAILURE(status)) {
 664                                 ACPI_EXCEPTION((AE_INFO, status,
 665                                                 "Unable to clear GPE[%2X]",
 666                                                 gpe_number));
 667                                 return_UINT32(ACPI_INTERRUPT_NOT_HANDLED);
 668                         }
 669                 }
 670                 break;
 671
 672         case ACPI_GPE_DISPATCH_METHOD:
 673
 674                 /*
 675                  * Disable the GPE, so it doesn't keep firing before the method has a
 676                  * chance to run (it runs asynchronously with interrupts enabled).
 677                  */
 678                 status = acpi_ev_disable_gpe(gpe_event_info);
 679                 if (ACPI_FAILURE(status)) {
 680                         ACPI_EXCEPTION((AE_INFO, status,
 681                                         "Unable to disable GPE[%2X]",
 682                                         gpe_number));
 683                         return_UINT32(ACPI_INTERRUPT_NOT_HANDLED);
 684                 }
 685
 686                 /*
 687                  * Execute the method associated with the GPE
 688                  * NOTE: Level-triggered GPEs are cleared after the method completes.
 689                  */
 690                 status = acpi_os_execute(OSL_GPE_HANDLER,
 691                                          acpi_ev_asynch_execute_gpe_method,
 692                                          gpe_event_info);
 693                 if (ACPI_FAILURE(status)) {
 694                         ACPI_EXCEPTION((AE_INFO, status,
 695                                         "Unable to queue handler for GPE[%2X] - event disabled",
 696                                         gpe_number));
 697                 }
 698                 break;
 699
 700         default:
 701
 702                 /* No handler or method to run! */
 703
 704                 ACPI_ERROR((AE_INFO,
 705                             "No handler or method for GPE[%2X], disabling event",
 706                             gpe_number));
 707
 708                 /*
 709                  * Disable the GPE. The GPE will remain disabled until the ACPICA
 710                  * Core Subsystem is restarted, or a handler is installed.
 711                  */
 712                 status = acpi_ev_disable_gpe(gpe_event_info);
 713                 if (ACPI_FAILURE(status)) {
 714                         ACPI_EXCEPTION((AE_INFO, status,
 715                                         "Unable to disable GPE[%2X]",
 716                                         gpe_number));
 717                         return_UINT32(ACPI_INTERRUPT_NOT_HANDLED);
 718                 }
 719                 break;
 720         }
 721
 722         return_UINT32(ACPI_INTERRUPT_HANDLED);
 723 }