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