drivers/acpi/acpica/hwregs.c

   1 /*******************************************************************************
   2  *
   3  * Module Name: hwregs - Read/write access functions for the various ACPI
   4  *                       control and status registers.
   5  *
   6  ******************************************************************************/
   7
   8 /*
   9  * Copyright (C) 2000 - 2016, Intel Corp.
  10  * All rights reserved.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions, and the following disclaimer,
  17  *    without modification.
  18  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
  19  *    substantially similar to the "NO WARRANTY" disclaimer below
  20  *    ("Disclaimer") and any redistribution must be conditioned upon
  21  *    including a substantially similar Disclaimer requirement for further
  22  *    binary redistribution.
  23  * 3. Neither the names of the above-listed copyright holders nor the names
  24  *    of any contributors may be used to endorse or promote products derived
  25  *    from this software without specific prior written permission.
  26  *
  27  * Alternatively, this software may be distributed under the terms of the
  28  * GNU General Public License ("GPL") version 2 as published by the Free
  29  * Software Foundation.
  30  *
  31  * NO WARRANTY
  32  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  33  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  34  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
  35  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  36  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  37  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  38  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  39  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  40  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  41  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  42  * POSSIBILITY OF SUCH DAMAGES.
  43  */
  44
  45 #include <acpi/acpi.h>
  46 #include "accommon.h"
  47 #include "acevents.h"
  48
  49 #define _COMPONENT          ACPI_HARDWARE
  50 ACPI_MODULE_NAME("hwregs")
  51
  52 #if (!ACPI_REDUCED_HARDWARE)
  53 /* Local Prototypes */
  54 static u8
  55 acpi_hw_get_access_bit_width(struct acpi_generic_address *reg,
  56                              u8 max_bit_width);
  57
  58 static acpi_status
  59 acpi_hw_read_multiple(u32 *value,
  60                       struct acpi_generic_address *register_a,
  61                       struct acpi_generic_address *register_b);
  62
  63 static acpi_status
  64 acpi_hw_write_multiple(u32 value,
  65                        struct acpi_generic_address *register_a,
  66                        struct acpi_generic_address *register_b);
  67
  68 #endif                          /* !ACPI_REDUCED_HARDWARE */
  69
  70 /******************************************************************************
  71  *
  72  * FUNCTION:    acpi_hw_get_access_bit_width
  73  *
  74  * PARAMETERS:  reg                 - GAS register structure
  75  *              max_bit_width       - Max bit_width supported (32 or 64)
  76  *
  77  * RETURN:      Status
  78  *
  79  * DESCRIPTION: Obtain optimal access bit width
  80  *
  81  ******************************************************************************/
  82
  83 static u8
  84 acpi_hw_get_access_bit_width(struct acpi_generic_address *reg, u8 max_bit_width)
  85 {
  86         u64 address;
  87
  88         if (!reg->access_width) {
  89                 /*
  90                  * Detect old register descriptors where only the bit_width field
  91                  * makes senses. The target address is copied to handle possible
  92                  * alignment issues.
  93                  */
  94                 ACPI_MOVE_64_TO_64(&address, &reg->address);
  95                 if (!reg->bit_offset && reg->bit_width &&
  96                     ACPI_IS_POWER_OF_TWO(reg->bit_width) &&
  97                     ACPI_IS_ALIGNED(reg->bit_width, 8) &&
  98                     ACPI_IS_ALIGNED(address, reg->bit_width)) {
  99                         return (reg->bit_width);
 100                 } else {
 101                         if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
 102                                 return (32);
 103                         } else {
 104                                 return (max_bit_width);
 105                         }
 106                 }
 107         } else {
 108                 return (1 << (reg->access_width + 2));
 109         }
 110 }
 111
 112 /******************************************************************************
 113  *
 114  * FUNCTION:    acpi_hw_validate_register
 115  *
 116  * PARAMETERS:  reg                 - GAS register structure
 117  *              max_bit_width       - Max bit_width supported (32 or 64)
 118  *              address             - Pointer to where the gas->address
 119  *                                    is returned
 120  *
 121  * RETURN:      Status
 122  *
 123  * DESCRIPTION: Validate the contents of a GAS register. Checks the GAS
 124  *              pointer, Address, space_id, bit_width, and bit_offset.
 125  *
 126  ******************************************************************************/
 127
 128 acpi_status
 129 acpi_hw_validate_register(struct acpi_generic_address *reg,
 130                           u8 max_bit_width, u64 *address)
 131 {
 132         u8 bit_width;
 133         u8 access_width;
 134
 135         /* Must have a valid pointer to a GAS structure */
 136
 137         if (!reg) {
 138                 return (AE_BAD_PARAMETER);
 139         }
 140
 141         /*
 142          * Copy the target address. This handles possible alignment issues.
 143          * Address must not be null. A null address also indicates an optional
 144          * ACPI register that is not supported, so no error message.
 145          */
 146         ACPI_MOVE_64_TO_64(address, &reg->address);
 147         if (!(*address)) {
 148                 return (AE_BAD_ADDRESS);
 149         }
 150
 151         /* Validate the space_ID */
 152
 153         if ((reg->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY) &&
 154             (reg->space_id != ACPI_ADR_SPACE_SYSTEM_IO)) {
 155                 ACPI_ERROR((AE_INFO,
 156                             "Unsupported address space: 0x%X", reg->space_id));
 157                 return (AE_SUPPORT);
 158         }
 159
 160         /* Validate the access_width */
 161
 162         if (reg->access_width > 4) {
 163                 ACPI_ERROR((AE_INFO,
 164                             "Unsupported register access width: 0x%X",
 165                             reg->access_width));
 166                 return (AE_SUPPORT);
 167         }
 168
 169         /* Validate the bit_width, convert access_width into number of bits */
 170
 171         access_width = acpi_hw_get_access_bit_width(reg, max_bit_width);
 172         bit_width =
 173             ACPI_ROUND_UP(reg->bit_offset + reg->bit_width, access_width);
 174         if (max_bit_width < bit_width) {
 175                 ACPI_WARNING((AE_INFO,
 176                               "Requested bit width 0x%X is smaller than register bit width 0x%X",
 177                               max_bit_width, bit_width));
 178                 return (AE_SUPPORT);
 179         }
 180
 181         return (AE_OK);
 182 }
 183
 184 /******************************************************************************
 185  *
 186  * FUNCTION:    acpi_hw_read
 187  *
 188  * PARAMETERS:  value               - Where the value is returned
 189  *              reg                 - GAS register structure
 190  *
 191  * RETURN:      Status
 192  *
 193  * DESCRIPTION: Read from either memory or IO space. This is a 32-bit max
 194  *              version of acpi_read, used internally since the overhead of
 195  *              64-bit values is not needed.
 196  *
 197  * LIMITATIONS: <These limitations also apply to acpi_hw_write>
 198  *      space_ID must be system_memory or system_IO.
 199  *
 200  ******************************************************************************/
 201
 202 acpi_status acpi_hw_read(u32 *value, struct acpi_generic_address *reg)
 203 {
 204         u64 address;
 205         u8 access_width;
 206         u32 bit_width;
 207         u8 bit_offset;
 208         u64 value64;
 209         u32 value32;
 210         u8 index;
 211         acpi_status status;
 212
 213         ACPI_FUNCTION_NAME(hw_read);
 214
 215         /* Validate contents of the GAS register */
 216
 217         status = acpi_hw_validate_register(reg, 32, &address);
 218         if (ACPI_FAILURE(status)) {
 219                 return (status);
 220         }
 221
 222         /*
 223          * Initialize entire 32-bit return value to zero, convert access_width
 224          * into number of bits based
 225          */
 226         *value = 0;
 227         access_width = acpi_hw_get_access_bit_width(reg, 32);
 228         bit_width = reg->bit_offset + reg->bit_width;
 229         bit_offset = reg->bit_offset;
 230
 231         /*
 232          * Two address spaces supported: Memory or IO. PCI_Config is
 233          * not supported here because the GAS structure is insufficient
 234          */
 235         index = 0;
 236         while (bit_width) {
 237                 if (bit_offset >= access_width) {
 238                         value32 = 0;
 239                         bit_offset -= access_width;
 240                 } else {
 241                         if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
 242                                 status =
 243                                     acpi_os_read_memory((acpi_physical_address)
 244                                                         address +
 245                                                         index *
 246                                                         ACPI_DIV_8
 247                                                         (access_width),
 248                                                         &value64, access_width);
 249                                 value32 = (u32)value64;
 250                         } else {        /* ACPI_ADR_SPACE_SYSTEM_IO, validated earlier */
 251
 252                                 status = acpi_hw_read_port((acpi_io_address)
 253                                                            address +
 254                                                            index *
 255                                                            ACPI_DIV_8
 256                                                            (access_width),
 257                                                            &value32,
 258                                                            access_width);
 259                         }
 260
 261                         /*
 262                          * Use offset style bit masks because:
 263                          * bit_offset < access_width/bit_width < access_width, and
 264                          * access_width is ensured to be less than 32-bits by
 265                          * acpi_hw_validate_register().
 266                          */
 267                         if (bit_offset) {
 268                                 value32 &= ACPI_MASK_BITS_BELOW(bit_offset);
 269                                 bit_offset = 0;
 270                         }
 271                         if (bit_width < access_width) {
 272                                 value32 &= ACPI_MASK_BITS_ABOVE(bit_width);
 273                         }
 274                 }
 275
 276                 /*
 277                  * Use offset style bit writes because "Index * AccessWidth" is
 278                  * ensured to be less than 32-bits by acpi_hw_validate_register().
 279                  */
 280                 ACPI_SET_BITS(value, index * access_width,
 281                               ACPI_MASK_BITS_ABOVE_32(access_width), value32);
 282
 283                 bit_width -=
 284                     bit_width > access_width ? access_width : bit_width;
 285                 index++;
 286         }
 287
 288         ACPI_DEBUG_PRINT((ACPI_DB_IO,
 289                           "Read:  %8.8X width %2d from %8.8X%8.8X (%s)\n",
 290                           *value, access_width, ACPI_FORMAT_UINT64(address),
 291                           acpi_ut_get_region_name(reg->space_id)));
 292
 293         return (status);
 294 }
 295
 296 /******************************************************************************
 297  *
 298  * FUNCTION:    acpi_hw_write
 299  *
 300  * PARAMETERS:  value               - Value to be written
 301  *              reg                 - GAS register structure
 302  *
 303  * RETURN:      Status
 304  *
 305  * DESCRIPTION: Write to either memory or IO space. This is a 32-bit max
 306  *              version of acpi_write, used internally since the overhead of
 307  *              64-bit values is not needed.
 308  *
 309  ******************************************************************************/
 310
 311 acpi_status acpi_hw_write(u32 value, struct acpi_generic_address *reg)
 312 {
 313         u64 address;
 314         acpi_status status;
 315
 316         ACPI_FUNCTION_NAME(hw_write);
 317
 318         /* Validate contents of the GAS register */
 319
 320         status = acpi_hw_validate_register(reg, 32, &address);
 321         if (ACPI_FAILURE(status)) {
 322                 return (status);
 323         }
 324
 325         /*
 326          * Two address spaces supported: Memory or IO. PCI_Config is
 327          * not supported here because the GAS structure is insufficient
 328          */
 329         if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
 330                 status = acpi_os_write_memory((acpi_physical_address)
 331                                               address, (u64)value,
 332                                               reg->bit_width);
 333         } else {                /* ACPI_ADR_SPACE_SYSTEM_IO, validated earlier */
 334
 335                 status = acpi_hw_write_port((acpi_io_address)
 336                                             address, value, reg->bit_width);
 337         }
 338
 339         ACPI_DEBUG_PRINT((ACPI_DB_IO,
 340                           "Wrote: %8.8X width %2d   to %8.8X%8.8X (%s)\n",
 341                           value, reg->bit_width, ACPI_FORMAT_UINT64(address),
 342                           acpi_ut_get_region_name(reg->space_id)));
 343
 344         return (status);
 345 }
 346
 347 #if (!ACPI_REDUCED_HARDWARE)
 348 /*******************************************************************************
 349  *
 350  * FUNCTION:    acpi_hw_clear_acpi_status
 351  *
 352  * PARAMETERS:  None
 353  *
 354  * RETURN:      Status
 355  *
 356  * DESCRIPTION: Clears all fixed and general purpose status bits
 357  *
 358  ******************************************************************************/
 359
 360 acpi_status acpi_hw_clear_acpi_status(void)
 361 {
 362         acpi_status status;
 363         acpi_cpu_flags lock_flags = 0;
 364
 365         ACPI_FUNCTION_TRACE(hw_clear_acpi_status);
 366
 367         ACPI_DEBUG_PRINT((ACPI_DB_IO, "About to write %04X to %8.8X%8.8X\n",
 368                           ACPI_BITMASK_ALL_FIXED_STATUS,
 369                           ACPI_FORMAT_UINT64(acpi_gbl_xpm1a_status.address)));
 370
 371         lock_flags = acpi_os_acquire_lock(acpi_gbl_hardware_lock);
 372
 373         /* Clear the fixed events in PM1 A/B */
 374
 375         status = acpi_hw_register_write(ACPI_REGISTER_PM1_STATUS,
 376                                         ACPI_BITMASK_ALL_FIXED_STATUS);
 377
 378         acpi_os_release_lock(acpi_gbl_hardware_lock, lock_flags);
 379
 380         if (ACPI_FAILURE(status)) {
 381                 goto exit;
 382         }
 383
 384         /* Clear the GPE Bits in all GPE registers in all GPE blocks */
 385
 386         status = acpi_ev_walk_gpe_list(acpi_hw_clear_gpe_block, NULL);
 387
 388 exit:
 389         return_ACPI_STATUS(status);
 390 }
 391
 392 /*******************************************************************************
 393  *
 394  * FUNCTION:    acpi_hw_get_bit_register_info
 395  *
 396  * PARAMETERS:  register_id         - Index of ACPI Register to access
 397  *
 398  * RETURN:      The bitmask to be used when accessing the register
 399  *
 400  * DESCRIPTION: Map register_id into a register bitmask.
 401  *
 402  ******************************************************************************/
 403
 404 struct acpi_bit_register_info *acpi_hw_get_bit_register_info(u32 register_id)
 405 {
 406         ACPI_FUNCTION_ENTRY();
 407
 408         if (register_id > ACPI_BITREG_MAX) {
 409                 ACPI_ERROR((AE_INFO, "Invalid BitRegister ID: 0x%X",
 410                             register_id));
 411                 return (NULL);
 412         }
 413
 414         return (&acpi_gbl_bit_register_info[register_id]);
 415 }
 416
 417 /******************************************************************************
 418  *
 419  * FUNCTION:    acpi_hw_write_pm1_control
 420  *
 421  * PARAMETERS:  pm1a_control        - Value to be written to PM1A control
 422  *              pm1b_control        - Value to be written to PM1B control
 423  *
 424  * RETURN:      Status
 425  *
 426  * DESCRIPTION: Write the PM1 A/B control registers. These registers are
 427  *              different than than the PM1 A/B status and enable registers
 428  *              in that different values can be written to the A/B registers.
 429  *              Most notably, the SLP_TYP bits can be different, as per the
 430  *              values returned from the _Sx predefined methods.
 431  *
 432  ******************************************************************************/
 433
 434 acpi_status acpi_hw_write_pm1_control(u32 pm1a_control, u32 pm1b_control)
 435 {
 436         acpi_status status;
 437
 438         ACPI_FUNCTION_TRACE(hw_write_pm1_control);
 439
 440         status =
 441             acpi_hw_write(pm1a_control, &acpi_gbl_FADT.xpm1a_control_block);
 442         if (ACPI_FAILURE(status)) {
 443                 return_ACPI_STATUS(status);
 444         }
 445
 446         if (acpi_gbl_FADT.xpm1b_control_block.address) {
 447                 status =
 448                     acpi_hw_write(pm1b_control,
 449                                   &acpi_gbl_FADT.xpm1b_control_block);
 450         }
 451         return_ACPI_STATUS(status);
 452 }
 453
 454 /******************************************************************************
 455  *
 456  * FUNCTION:    acpi_hw_register_read
 457  *
 458  * PARAMETERS:  register_id         - ACPI Register ID
 459  *              return_value        - Where the register value is returned
 460  *
 461  * RETURN:      Status and the value read.
 462  *
 463  * DESCRIPTION: Read from the specified ACPI register
 464  *
 465  ******************************************************************************/
 466 acpi_status acpi_hw_register_read(u32 register_id, u32 *return_value)
 467 {
 468         u32 value = 0;
 469         acpi_status status;
 470
 471         ACPI_FUNCTION_TRACE(hw_register_read);
 472
 473         switch (register_id) {
 474         case ACPI_REGISTER_PM1_STATUS:  /* PM1 A/B: 16-bit access each */
 475
 476                 status = acpi_hw_read_multiple(&value,
 477                                                &acpi_gbl_xpm1a_status,
 478                                                &acpi_gbl_xpm1b_status);
 479                 break;
 480
 481         case ACPI_REGISTER_PM1_ENABLE:  /* PM1 A/B: 16-bit access each */
 482
 483                 status = acpi_hw_read_multiple(&value,
 484                                                &acpi_gbl_xpm1a_enable,
 485                                                &acpi_gbl_xpm1b_enable);
 486                 break;
 487
 488         case ACPI_REGISTER_PM1_CONTROL: /* PM1 A/B: 16-bit access each */
 489
 490                 status = acpi_hw_read_multiple(&value,
 491                                                &acpi_gbl_FADT.
 492                                                xpm1a_control_block,
 493                                                &acpi_gbl_FADT.
 494                                                xpm1b_control_block);
 495
 496                 /*
 497                  * Zero the write-only bits. From the ACPI specification, "Hardware
 498                  * Write-Only Bits": "Upon reads to registers with write-only bits,
 499                  * software masks out all write-only bits."
 500                  */
 501                 value &= ~ACPI_PM1_CONTROL_WRITEONLY_BITS;
 502                 break;
 503
 504         case ACPI_REGISTER_PM2_CONTROL: /* 8-bit access */
 505
 506                 status =
 507                     acpi_hw_read(&value, &acpi_gbl_FADT.xpm2_control_block);
 508                 break;
 509
 510         case ACPI_REGISTER_PM_TIMER:    /* 32-bit access */
 511
 512                 status = acpi_hw_read(&value, &acpi_gbl_FADT.xpm_timer_block);
 513                 break;
 514
 515         case ACPI_REGISTER_SMI_COMMAND_BLOCK:   /* 8-bit access */
 516
 517                 status =
 518                     acpi_hw_read_port(acpi_gbl_FADT.smi_command, &value, 8);
 519                 break;
 520
 521         default:
 522
 523                 ACPI_ERROR((AE_INFO, "Unknown Register ID: 0x%X", register_id));
 524                 status = AE_BAD_PARAMETER;
 525                 break;
 526         }
 527
 528         if (ACPI_SUCCESS(status)) {
 529                 *return_value = value;
 530         }
 531
 532         return_ACPI_STATUS(status);
 533 }
 534
 535 /******************************************************************************
 536  *
 537  * FUNCTION:    acpi_hw_register_write
 538  *
 539  * PARAMETERS:  register_id         - ACPI Register ID
 540  *              value               - The value to write
 541  *
 542  * RETURN:      Status
 543  *
 544  * DESCRIPTION: Write to the specified ACPI register
 545  *
 546  * NOTE: In accordance with the ACPI specification, this function automatically
 547  * preserves the value of the following bits, meaning that these bits cannot be
 548  * changed via this interface:
 549  *
 550  * PM1_CONTROL[0] = SCI_EN
 551  * PM1_CONTROL[9]
 552  * PM1_STATUS[11]
 553  *
 554  * ACPI References:
 555  * 1) Hardware Ignored Bits: When software writes to a register with ignored
 556  *      bit fields, it preserves the ignored bit fields
 557  * 2) SCI_EN: OSPM always preserves this bit position
 558  *
 559  ******************************************************************************/
 560
 561 acpi_status acpi_hw_register_write(u32 register_id, u32 value)
 562 {
 563         acpi_status status;
 564         u32 read_value;
 565
 566         ACPI_FUNCTION_TRACE(hw_register_write);
 567
 568         switch (register_id) {
 569         case ACPI_REGISTER_PM1_STATUS:  /* PM1 A/B: 16-bit access each */
 570                 /*
 571                  * Handle the "ignored" bit in PM1 Status. According to the ACPI
 572                  * specification, ignored bits are to be preserved when writing.
 573                  * Normally, this would mean a read/modify/write sequence. However,
 574                  * preserving a bit in the status register is different. Writing a
 575                  * one clears the status, and writing a zero preserves the status.
 576                  * Therefore, we must always write zero to the ignored bit.
 577                  *
 578                  * This behavior is clarified in the ACPI 4.0 specification.
 579                  */
 580                 value &= ~ACPI_PM1_STATUS_PRESERVED_BITS;
 581
 582                 status = acpi_hw_write_multiple(value,
 583                                                 &acpi_gbl_xpm1a_status,
 584                                                 &acpi_gbl_xpm1b_status);
 585                 break;
 586
 587         case ACPI_REGISTER_PM1_ENABLE:  /* PM1 A/B: 16-bit access each */
 588
 589                 status = acpi_hw_write_multiple(value,
 590                                                 &acpi_gbl_xpm1a_enable,
 591                                                 &acpi_gbl_xpm1b_enable);
 592                 break;
 593
 594         case ACPI_REGISTER_PM1_CONTROL: /* PM1 A/B: 16-bit access each */
 595                 /*
 596                  * Perform a read first to preserve certain bits (per ACPI spec)
 597                  * Note: This includes SCI_EN, we never want to change this bit
 598                  */
 599                 status = acpi_hw_read_multiple(&read_value,
 600                                                &acpi_gbl_FADT.
 601                                                xpm1a_control_block,
 602                                                &acpi_gbl_FADT.
 603                                                xpm1b_control_block);
 604                 if (ACPI_FAILURE(status)) {
 605                         goto exit;
 606                 }
 607
 608                 /* Insert the bits to be preserved */
 609
 610                 ACPI_INSERT_BITS(value, ACPI_PM1_CONTROL_PRESERVED_BITS,
 611                                  read_value);
 612
 613                 /* Now we can write the data */
 614
 615                 status = acpi_hw_write_multiple(value,
 616                                                 &acpi_gbl_FADT.
 617                                                 xpm1a_control_block,
 618                                                 &acpi_gbl_FADT.
 619                                                 xpm1b_control_block);
 620                 break;
 621
 622         case ACPI_REGISTER_PM2_CONTROL: /* 8-bit access */
 623                 /*
 624                  * For control registers, all reserved bits must be preserved,
 625                  * as per the ACPI spec.
 626                  */
 627                 status =
 628                     acpi_hw_read(&read_value,
 629                                  &acpi_gbl_FADT.xpm2_control_block);
 630                 if (ACPI_FAILURE(status)) {
 631                         goto exit;
 632                 }
 633
 634                 /* Insert the bits to be preserved */
 635
 636                 ACPI_INSERT_BITS(value, ACPI_PM2_CONTROL_PRESERVED_BITS,
 637                                  read_value);
 638
 639                 status =
 640                     acpi_hw_write(value, &acpi_gbl_FADT.xpm2_control_block);
 641                 break;
 642
 643         case ACPI_REGISTER_PM_TIMER:    /* 32-bit access */
 644
 645                 status = acpi_hw_write(value, &acpi_gbl_FADT.xpm_timer_block);
 646                 break;
 647
 648         case ACPI_REGISTER_SMI_COMMAND_BLOCK:   /* 8-bit access */
 649
 650                 /* SMI_CMD is currently always in IO space */
 651
 652                 status =
 653                     acpi_hw_write_port(acpi_gbl_FADT.smi_command, value, 8);
 654                 break;
 655
 656         default:
 657
 658                 ACPI_ERROR((AE_INFO, "Unknown Register ID: 0x%X", register_id));
 659                 status = AE_BAD_PARAMETER;
 660                 break;
 661         }
 662
 663 exit:
 664         return_ACPI_STATUS(status);
 665 }
 666
 667 /******************************************************************************
 668  *
 669  * FUNCTION:    acpi_hw_read_multiple
 670  *
 671  * PARAMETERS:  value               - Where the register value is returned
 672  *              register_a           - First ACPI register (required)
 673  *              register_b           - Second ACPI register (optional)
 674  *
 675  * RETURN:      Status
 676  *
 677  * DESCRIPTION: Read from the specified two-part ACPI register (such as PM1 A/B)
 678  *
 679  ******************************************************************************/
 680
 681 static acpi_status
 682 acpi_hw_read_multiple(u32 *value,
 683                       struct acpi_generic_address *register_a,
 684                       struct acpi_generic_address *register_b)
 685 {
 686         u32 value_a = 0;
 687         u32 value_b = 0;
 688         acpi_status status;
 689
 690         /* The first register is always required */
 691
 692         status = acpi_hw_read(&value_a, register_a);
 693         if (ACPI_FAILURE(status)) {
 694                 return (status);
 695         }
 696
 697         /* Second register is optional */
 698
 699         if (register_b->address) {
 700                 status = acpi_hw_read(&value_b, register_b);
 701                 if (ACPI_FAILURE(status)) {
 702                         return (status);
 703                 }
 704         }
 705
 706         /*
 707          * OR the two return values together. No shifting or masking is necessary,
 708          * because of how the PM1 registers are defined in the ACPI specification:
 709          *
 710          * "Although the bits can be split between the two register blocks (each
 711          * register block has a unique pointer within the FADT), the bit positions
 712          * are maintained. The register block with unimplemented bits (that is,
 713          * those implemented in the other register block) always returns zeros,
 714          * and writes have no side effects"
 715          */
 716         *value = (value_a | value_b);
 717         return (AE_OK);
 718 }
 719
 720 /******************************************************************************
 721  *
 722  * FUNCTION:    acpi_hw_write_multiple
 723  *
 724  * PARAMETERS:  value               - The value to write
 725  *              register_a           - First ACPI register (required)
 726  *              register_b           - Second ACPI register (optional)
 727  *
 728  * RETURN:      Status
 729  *
 730  * DESCRIPTION: Write to the specified two-part ACPI register (such as PM1 A/B)
 731  *
 732  ******************************************************************************/
 733
 734 static acpi_status
 735 acpi_hw_write_multiple(u32 value,
 736                        struct acpi_generic_address *register_a,
 737                        struct acpi_generic_address *register_b)
 738 {
 739         acpi_status status;
 740
 741         /* The first register is always required */
 742
 743         status = acpi_hw_write(value, register_a);
 744         if (ACPI_FAILURE(status)) {
 745                 return (status);
 746         }
 747
 748         /*
 749          * Second register is optional
 750          *
 751          * No bit shifting or clearing is necessary, because of how the PM1
 752          * registers are defined in the ACPI specification:
 753          *
 754          * "Although the bits can be split between the two register blocks (each
 755          * register block has a unique pointer within the FADT), the bit positions
 756          * are maintained. The register block with unimplemented bits (that is,
 757          * those implemented in the other register block) always returns zeros,
 758          * and writes have no side effects"
 759          */
 760         if (register_b->address) {
 761                 status = acpi_hw_write(value, register_b);
 762         }
 763
 764         return (status);
 765 }
 766
 767 #endif                          /* !ACPI_REDUCED_HARDWARE */