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 - 2017, 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(u64 address,
  56                              struct acpi_generic_address *reg,
  57                              u8 max_bit_width);
  58
  59 static acpi_status
  60 acpi_hw_read_multiple(u32 *value,
  61                       struct acpi_generic_address *register_a,
  62                       struct acpi_generic_address *register_b);
  63
  64 static acpi_status
  65 acpi_hw_write_multiple(u32 value,
  66                        struct acpi_generic_address *register_a,
  67                        struct acpi_generic_address *register_b);
  68
  69 #endif                          /* !ACPI_REDUCED_HARDWARE */
  70
  71 /******************************************************************************
  72  *
  73  * FUNCTION:    acpi_hw_get_access_bit_width
  74  *
  75  * PARAMETERS:  address             - GAS register address
  76  *              reg                 - GAS register structure
  77  *              max_bit_width       - Max bit_width supported (32 or 64)
  78  *
  79  * RETURN:      Status
  80  *
  81  * DESCRIPTION: Obtain optimal access bit width
  82  *
  83  ******************************************************************************/
  84
  85 static u8
  86 acpi_hw_get_access_bit_width(u64 address,
  87                              struct acpi_generic_address *reg, u8 max_bit_width)
  88 {
  89         u8 access_bit_width;
  90
  91         /*
  92          * GAS format "register", used by FADT:
  93          *  1. Detected if bit_offset is 0 and bit_width is 8/16/32/64;
  94          *  2. access_size field is ignored and bit_width field is used for
  95          *     determining the boundary of the IO accesses.
  96          * GAS format "region", used by APEI registers:
  97          *  1. Detected if bit_offset is not 0 or bit_width is not 8/16/32/64;
  98          *  2. access_size field is used for determining the boundary of the
  99          *     IO accesses;
 100          *  3. bit_offset/bit_width fields are used to describe the "region".
 101          *
 102          * Note: This algorithm assumes that the "Address" fields should always
 103          *       contain aligned values.
 104          */
 105         if (!reg->bit_offset && reg->bit_width &&
 106             ACPI_IS_POWER_OF_TWO(reg->bit_width) &&
 107             ACPI_IS_ALIGNED(reg->bit_width, 8)) {
 108                 access_bit_width = reg->bit_width;
 109         } else if (reg->access_width) {
 110                 access_bit_width = ACPI_ACCESS_BIT_WIDTH(reg->access_width);
 111         } else {
 112                 access_bit_width =
 113                     ACPI_ROUND_UP_POWER_OF_TWO_8(reg->bit_offset +
 114                                                  reg->bit_width);
 115                 if (access_bit_width <= 8) {
 116                         access_bit_width = 8;
 117                 } else {
 118                         while (!ACPI_IS_ALIGNED(address, access_bit_width >> 3)) {
 119                                 access_bit_width >>= 1;
 120                         }
 121                 }
 122         }
 123
 124         /* Maximum IO port access bit width is 32 */
 125
 126         if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
 127                 max_bit_width = 32;
 128         }
 129
 130         /*
 131          * Return access width according to the requested maximum access bit width,
 132          * as the caller should know the format of the register and may enforce
 133          * a 32-bit accesses.
 134          */
 135         if (access_bit_width < max_bit_width) {
 136                 return (access_bit_width);
 137         }
 138         return (max_bit_width);
 139 }
 140
 141 /******************************************************************************
 142  *
 143  * FUNCTION:    acpi_hw_validate_register
 144  *
 145  * PARAMETERS:  reg                 - GAS register structure
 146  *              max_bit_width       - Max bit_width supported (32 or 64)
 147  *              address             - Pointer to where the gas->address
 148  *                                    is returned
 149  *
 150  * RETURN:      Status
 151  *
 152  * DESCRIPTION: Validate the contents of a GAS register. Checks the GAS
 153  *              pointer, Address, space_id, bit_width, and bit_offset.
 154  *
 155  ******************************************************************************/
 156
 157 acpi_status
 158 acpi_hw_validate_register(struct acpi_generic_address *reg,
 159                           u8 max_bit_width, u64 *address)
 160 {
 161         u8 bit_width;
 162         u8 access_width;
 163
 164         /* Must have a valid pointer to a GAS structure */
 165
 166         if (!reg) {
 167                 return (AE_BAD_PARAMETER);
 168         }
 169
 170         /*
 171          * Copy the target address. This handles possible alignment issues.
 172          * Address must not be null. A null address also indicates an optional
 173          * ACPI register that is not supported, so no error message.
 174          */
 175         ACPI_MOVE_64_TO_64(address, &reg->address);
 176         if (!(*address)) {
 177                 return (AE_BAD_ADDRESS);
 178         }
 179
 180         /* Validate the space_ID */
 181
 182         if ((reg->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY) &&
 183             (reg->space_id != ACPI_ADR_SPACE_SYSTEM_IO)) {
 184                 ACPI_ERROR((AE_INFO,
 185                             "Unsupported address space: 0x%X", reg->space_id));
 186                 return (AE_SUPPORT);
 187         }
 188
 189         /* Validate the access_width */
 190
 191         if (reg->access_width > 4) {
 192                 ACPI_ERROR((AE_INFO,
 193                             "Unsupported register access width: 0x%X",
 194                             reg->access_width));
 195                 return (AE_SUPPORT);
 196         }
 197
 198         /* Validate the bit_width, convert access_width into number of bits */
 199
 200         access_width =
 201             acpi_hw_get_access_bit_width(*address, reg, max_bit_width);
 202         bit_width =
 203             ACPI_ROUND_UP(reg->bit_offset + reg->bit_width, access_width);
 204         if (max_bit_width < bit_width) {
 205                 ACPI_WARNING((AE_INFO,
 206                               "Requested bit width 0x%X is smaller than register bit width 0x%X",
 207                               max_bit_width, bit_width));
 208                 return (AE_SUPPORT);
 209         }
 210
 211         return (AE_OK);
 212 }
 213
 214 /******************************************************************************
 215  *
 216  * FUNCTION:    acpi_hw_read
 217  *
 218  * PARAMETERS:  value               - Where the value is returned
 219  *              reg                 - GAS register structure
 220  *
 221  * RETURN:      Status
 222  *
 223  * DESCRIPTION: Read from either memory or IO space. This is a 32-bit max
 224  *              version of acpi_read, used internally since the overhead of
 225  *              64-bit values is not needed.
 226  *
 227  * LIMITATIONS: <These limitations also apply to acpi_hw_write>
 228  *      space_ID must be system_memory or system_IO.
 229  *
 230  ******************************************************************************/
 231
 232 acpi_status acpi_hw_read(u32 *value, struct acpi_generic_address *reg)
 233 {
 234         u64 address;
 235         u8 access_width;
 236         u32 bit_width;
 237         u8 bit_offset;
 238         u64 value64;
 239         u32 value32;
 240         u8 index;
 241         acpi_status status;
 242
 243         ACPI_FUNCTION_NAME(hw_read);
 244
 245         /* Validate contents of the GAS register */
 246
 247         status = acpi_hw_validate_register(reg, 32, &address);
 248         if (ACPI_FAILURE(status)) {
 249                 return (status);
 250         }
 251
 252         /*
 253          * Initialize entire 32-bit return value to zero, convert access_width
 254          * into number of bits based
 255          */
 256         *value = 0;
 257         access_width = acpi_hw_get_access_bit_width(address, reg, 32);
 258         bit_width = reg->bit_offset + reg->bit_width;
 259         bit_offset = reg->bit_offset;
 260
 261         /*
 262          * Two address spaces supported: Memory or IO. PCI_Config is
 263          * not supported here because the GAS structure is insufficient
 264          */
 265         index = 0;
 266         while (bit_width) {
 267                 if (bit_offset >= access_width) {
 268                         value32 = 0;
 269                         bit_offset -= access_width;
 270                 } else {
 271                         if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
 272                                 status =
 273                                     acpi_os_read_memory((acpi_physical_address)
 274                                                         address +
 275                                                         index *
 276                                                         ACPI_DIV_8
 277                                                         (access_width),
 278                                                         &value64, access_width);
 279                                 value32 = (u32)value64;
 280                         } else {        /* ACPI_ADR_SPACE_SYSTEM_IO, validated earlier */
 281
 282                                 status = acpi_hw_read_port((acpi_io_address)
 283                                                            address +
 284                                                            index *
 285                                                            ACPI_DIV_8
 286                                                            (access_width),
 287                                                            &value32,
 288                                                            access_width);
 289                         }
 290                 }
 291
 292                 /*
 293                  * Use offset style bit writes because "Index * AccessWidth" is
 294                  * ensured to be less than 32-bits by acpi_hw_validate_register().
 295                  */
 296                 ACPI_SET_BITS(value, index * access_width,
 297                               ACPI_MASK_BITS_ABOVE_32(access_width), value32);
 298
 299                 bit_width -=
 300                     bit_width > access_width ? access_width : bit_width;
 301                 index++;
 302         }
 303
 304         ACPI_DEBUG_PRINT((ACPI_DB_IO,
 305                           "Read:  %8.8X width %2d from %8.8X%8.8X (%s)\n",
 306                           *value, access_width, ACPI_FORMAT_UINT64(address),
 307                           acpi_ut_get_region_name(reg->space_id)));
 308
 309         return (status);
 310 }
 311
 312 /******************************************************************************
 313  *
 314  * FUNCTION:    acpi_hw_write
 315  *
 316  * PARAMETERS:  value               - Value to be written
 317  *              reg                 - GAS register structure
 318  *
 319  * RETURN:      Status
 320  *
 321  * DESCRIPTION: Write to either memory or IO space. This is a 32-bit max
 322  *              version of acpi_write, used internally since the overhead of
 323  *              64-bit values is not needed.
 324  *
 325  ******************************************************************************/
 326
 327 acpi_status acpi_hw_write(u32 value, struct acpi_generic_address *reg)
 328 {
 329         u64 address;
 330         u8 access_width;
 331         u32 bit_width;
 332         u8 bit_offset;
 333         u64 value64;
 334         u32 value32;
 335         u8 index;
 336         acpi_status status;
 337
 338         ACPI_FUNCTION_NAME(hw_write);
 339
 340         /* Validate contents of the GAS register */
 341
 342         status = acpi_hw_validate_register(reg, 32, &address);
 343         if (ACPI_FAILURE(status)) {
 344                 return (status);
 345         }
 346
 347         /* Convert access_width into number of bits based */
 348
 349         access_width = acpi_hw_get_access_bit_width(address, reg, 32);
 350         bit_width = reg->bit_offset + reg->bit_width;
 351         bit_offset = reg->bit_offset;
 352
 353         /*
 354          * Two address spaces supported: Memory or IO. PCI_Config is
 355          * not supported here because the GAS structure is insufficient
 356          */
 357         index = 0;
 358         while (bit_width) {
 359                 /*
 360                  * Use offset style bit reads because "Index * AccessWidth" is
 361                  * ensured to be less than 32-bits by acpi_hw_validate_register().
 362                  */
 363                 value32 = ACPI_GET_BITS(&value, index * access_width,
 364                                         ACPI_MASK_BITS_ABOVE_32(access_width));
 365
 366                 if (bit_offset >= access_width) {
 367                         bit_offset -= access_width;
 368                 } else {
 369                         if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
 370                                 value64 = (u64)value32;
 371                                 status =
 372                                     acpi_os_write_memory((acpi_physical_address)
 373                                                          address +
 374                                                          index *
 375                                                          ACPI_DIV_8
 376                                                          (access_width),
 377                                                          value64, access_width);
 378                         } else {        /* ACPI_ADR_SPACE_SYSTEM_IO, validated earlier */
 379
 380                                 status = acpi_hw_write_port((acpi_io_address)
 381                                                             address +
 382                                                             index *
 383                                                             ACPI_DIV_8
 384                                                             (access_width),
 385                                                             value32,
 386                                                             access_width);
 387                         }
 388                 }
 389
 390                 /*
 391                  * Index * access_width is ensured to be less than 32-bits by
 392                  * acpi_hw_validate_register().
 393                  */
 394                 bit_width -=
 395                     bit_width > access_width ? access_width : bit_width;
 396                 index++;
 397         }
 398
 399         ACPI_DEBUG_PRINT((ACPI_DB_IO,
 400                           "Wrote: %8.8X width %2d   to %8.8X%8.8X (%s)\n",
 401                           value, access_width, ACPI_FORMAT_UINT64(address),
 402                           acpi_ut_get_region_name(reg->space_id)));
 403
 404         return (status);
 405 }
 406
 407 #if (!ACPI_REDUCED_HARDWARE)
 408 /*******************************************************************************
 409  *
 410  * FUNCTION:    acpi_hw_clear_acpi_status
 411  *
 412  * PARAMETERS:  None
 413  *
 414  * RETURN:      Status
 415  *
 416  * DESCRIPTION: Clears all fixed and general purpose status bits
 417  *
 418  ******************************************************************************/
 419
 420 acpi_status acpi_hw_clear_acpi_status(void)
 421 {
 422         acpi_status status;
 423         acpi_cpu_flags lock_flags = 0;
 424
 425         ACPI_FUNCTION_TRACE(hw_clear_acpi_status);
 426
 427         ACPI_DEBUG_PRINT((ACPI_DB_IO, "About to write %04X to %8.8X%8.8X\n",
 428                           ACPI_BITMASK_ALL_FIXED_STATUS,
 429                           ACPI_FORMAT_UINT64(acpi_gbl_xpm1a_status.address)));
 430
 431         lock_flags = acpi_os_acquire_lock(acpi_gbl_hardware_lock);
 432
 433         /* Clear the fixed events in PM1 A/B */
 434
 435         status = acpi_hw_register_write(ACPI_REGISTER_PM1_STATUS,
 436                                         ACPI_BITMASK_ALL_FIXED_STATUS);
 437
 438         acpi_os_release_lock(acpi_gbl_hardware_lock, lock_flags);
 439
 440         if (ACPI_FAILURE(status)) {
 441                 goto exit;
 442         }
 443
 444         /* Clear the GPE Bits in all GPE registers in all GPE blocks */
 445
 446         status = acpi_ev_walk_gpe_list(acpi_hw_clear_gpe_block, NULL);
 447
 448 exit:
 449         return_ACPI_STATUS(status);
 450 }
 451
 452 /*******************************************************************************
 453  *
 454  * FUNCTION:    acpi_hw_get_bit_register_info
 455  *
 456  * PARAMETERS:  register_id         - Index of ACPI Register to access
 457  *
 458  * RETURN:      The bitmask to be used when accessing the register
 459  *
 460  * DESCRIPTION: Map register_id into a register bitmask.
 461  *
 462  ******************************************************************************/
 463
 464 struct acpi_bit_register_info *acpi_hw_get_bit_register_info(u32 register_id)
 465 {
 466         ACPI_FUNCTION_ENTRY();
 467
 468         if (register_id > ACPI_BITREG_MAX) {
 469                 ACPI_ERROR((AE_INFO, "Invalid BitRegister ID: 0x%X",
 470                             register_id));
 471                 return (NULL);
 472         }
 473
 474         return (&acpi_gbl_bit_register_info[register_id]);
 475 }
 476
 477 /******************************************************************************
 478  *
 479  * FUNCTION:    acpi_hw_write_pm1_control
 480  *
 481  * PARAMETERS:  pm1a_control        - Value to be written to PM1A control
 482  *              pm1b_control        - Value to be written to PM1B control
 483  *
 484  * RETURN:      Status
 485  *
 486  * DESCRIPTION: Write the PM1 A/B control registers. These registers are
 487  *              different than than the PM1 A/B status and enable registers
 488  *              in that different values can be written to the A/B registers.
 489  *              Most notably, the SLP_TYP bits can be different, as per the
 490  *              values returned from the _Sx predefined methods.
 491  *
 492  ******************************************************************************/
 493
 494 acpi_status acpi_hw_write_pm1_control(u32 pm1a_control, u32 pm1b_control)
 495 {
 496         acpi_status status;
 497
 498         ACPI_FUNCTION_TRACE(hw_write_pm1_control);
 499
 500         status =
 501             acpi_hw_write(pm1a_control, &acpi_gbl_FADT.xpm1a_control_block);
 502         if (ACPI_FAILURE(status)) {
 503                 return_ACPI_STATUS(status);
 504         }
 505
 506         if (acpi_gbl_FADT.xpm1b_control_block.address) {
 507                 status =
 508                     acpi_hw_write(pm1b_control,
 509                                   &acpi_gbl_FADT.xpm1b_control_block);
 510         }
 511         return_ACPI_STATUS(status);
 512 }
 513
 514 /******************************************************************************
 515  *
 516  * FUNCTION:    acpi_hw_register_read
 517  *
 518  * PARAMETERS:  register_id         - ACPI Register ID
 519  *              return_value        - Where the register value is returned
 520  *
 521  * RETURN:      Status and the value read.
 522  *
 523  * DESCRIPTION: Read from the specified ACPI register
 524  *
 525  ******************************************************************************/
 526 acpi_status acpi_hw_register_read(u32 register_id, u32 *return_value)
 527 {
 528         u32 value = 0;
 529         acpi_status status;
 530
 531         ACPI_FUNCTION_TRACE(hw_register_read);
 532
 533         switch (register_id) {
 534         case ACPI_REGISTER_PM1_STATUS:  /* PM1 A/B: 16-bit access each */
 535
 536                 status = acpi_hw_read_multiple(&value,
 537                                                &acpi_gbl_xpm1a_status,
 538                                                &acpi_gbl_xpm1b_status);
 539                 break;
 540
 541         case ACPI_REGISTER_PM1_ENABLE:  /* PM1 A/B: 16-bit access each */
 542
 543                 status = acpi_hw_read_multiple(&value,
 544                                                &acpi_gbl_xpm1a_enable,
 545                                                &acpi_gbl_xpm1b_enable);
 546                 break;
 547
 548         case ACPI_REGISTER_PM1_CONTROL: /* PM1 A/B: 16-bit access each */
 549
 550                 status = acpi_hw_read_multiple(&value,
 551                                                &acpi_gbl_FADT.
 552                                                xpm1a_control_block,
 553                                                &acpi_gbl_FADT.
 554                                                xpm1b_control_block);
 555
 556                 /*
 557                  * Zero the write-only bits. From the ACPI specification, "Hardware
 558                  * Write-Only Bits": "Upon reads to registers with write-only bits,
 559                  * software masks out all write-only bits."
 560                  */
 561                 value &= ~ACPI_PM1_CONTROL_WRITEONLY_BITS;
 562                 break;
 563
 564         case ACPI_REGISTER_PM2_CONTROL: /* 8-bit access */
 565
 566                 status =
 567                     acpi_hw_read(&value, &acpi_gbl_FADT.xpm2_control_block);
 568                 break;
 569
 570         case ACPI_REGISTER_PM_TIMER:    /* 32-bit access */
 571
 572                 status = acpi_hw_read(&value, &acpi_gbl_FADT.xpm_timer_block);
 573                 break;
 574
 575         case ACPI_REGISTER_SMI_COMMAND_BLOCK:   /* 8-bit access */
 576
 577                 status =
 578                     acpi_hw_read_port(acpi_gbl_FADT.smi_command, &value, 8);
 579                 break;
 580
 581         default:
 582
 583                 ACPI_ERROR((AE_INFO, "Unknown Register ID: 0x%X", register_id));
 584                 status = AE_BAD_PARAMETER;
 585                 break;
 586         }
 587
 588         if (ACPI_SUCCESS(status)) {
 589                 *return_value = value;
 590         }
 591
 592         return_ACPI_STATUS(status);
 593 }
 594
 595 /******************************************************************************
 596  *
 597  * FUNCTION:    acpi_hw_register_write
 598  *
 599  * PARAMETERS:  register_id         - ACPI Register ID
 600  *              value               - The value to write
 601  *
 602  * RETURN:      Status
 603  *
 604  * DESCRIPTION: Write to the specified ACPI register
 605  *
 606  * NOTE: In accordance with the ACPI specification, this function automatically
 607  * preserves the value of the following bits, meaning that these bits cannot be
 608  * changed via this interface:
 609  *
 610  * PM1_CONTROL[0] = SCI_EN
 611  * PM1_CONTROL[9]
 612  * PM1_STATUS[11]
 613  *
 614  * ACPI References:
 615  * 1) Hardware Ignored Bits: When software writes to a register with ignored
 616  *      bit fields, it preserves the ignored bit fields
 617  * 2) SCI_EN: OSPM always preserves this bit position
 618  *
 619  ******************************************************************************/
 620
 621 acpi_status acpi_hw_register_write(u32 register_id, u32 value)
 622 {
 623         acpi_status status;
 624         u32 read_value;
 625
 626         ACPI_FUNCTION_TRACE(hw_register_write);
 627
 628         switch (register_id) {
 629         case ACPI_REGISTER_PM1_STATUS:  /* PM1 A/B: 16-bit access each */
 630                 /*
 631                  * Handle the "ignored" bit in PM1 Status. According to the ACPI
 632                  * specification, ignored bits are to be preserved when writing.
 633                  * Normally, this would mean a read/modify/write sequence. However,
 634                  * preserving a bit in the status register is different. Writing a
 635                  * one clears the status, and writing a zero preserves the status.
 636                  * Therefore, we must always write zero to the ignored bit.
 637                  *
 638                  * This behavior is clarified in the ACPI 4.0 specification.
 639                  */
 640                 value &= ~ACPI_PM1_STATUS_PRESERVED_BITS;
 641
 642                 status = acpi_hw_write_multiple(value,
 643                                                 &acpi_gbl_xpm1a_status,
 644                                                 &acpi_gbl_xpm1b_status);
 645                 break;
 646
 647         case ACPI_REGISTER_PM1_ENABLE:  /* PM1 A/B: 16-bit access each */
 648
 649                 status = acpi_hw_write_multiple(value,
 650                                                 &acpi_gbl_xpm1a_enable,
 651                                                 &acpi_gbl_xpm1b_enable);
 652                 break;
 653
 654         case ACPI_REGISTER_PM1_CONTROL: /* PM1 A/B: 16-bit access each */
 655                 /*
 656                  * Perform a read first to preserve certain bits (per ACPI spec)
 657                  * Note: This includes SCI_EN, we never want to change this bit
 658                  */
 659                 status = acpi_hw_read_multiple(&read_value,
 660                                                &acpi_gbl_FADT.
 661                                                xpm1a_control_block,
 662                                                &acpi_gbl_FADT.
 663                                                xpm1b_control_block);
 664                 if (ACPI_FAILURE(status)) {
 665                         goto exit;
 666                 }
 667
 668                 /* Insert the bits to be preserved */
 669
 670                 ACPI_INSERT_BITS(value, ACPI_PM1_CONTROL_PRESERVED_BITS,
 671                                  read_value);
 672
 673                 /* Now we can write the data */
 674
 675                 status = acpi_hw_write_multiple(value,
 676                                                 &acpi_gbl_FADT.
 677                                                 xpm1a_control_block,
 678                                                 &acpi_gbl_FADT.
 679                                                 xpm1b_control_block);
 680                 break;
 681
 682         case ACPI_REGISTER_PM2_CONTROL: /* 8-bit access */
 683                 /*
 684                  * For control registers, all reserved bits must be preserved,
 685                  * as per the ACPI spec.
 686                  */
 687                 status =
 688                     acpi_hw_read(&read_value,
 689                                  &acpi_gbl_FADT.xpm2_control_block);
 690                 if (ACPI_FAILURE(status)) {
 691                         goto exit;
 692                 }
 693
 694                 /* Insert the bits to be preserved */
 695
 696                 ACPI_INSERT_BITS(value, ACPI_PM2_CONTROL_PRESERVED_BITS,
 697                                  read_value);
 698
 699                 status =
 700                     acpi_hw_write(value, &acpi_gbl_FADT.xpm2_control_block);
 701                 break;
 702
 703         case ACPI_REGISTER_PM_TIMER:    /* 32-bit access */
 704
 705                 status = acpi_hw_write(value, &acpi_gbl_FADT.xpm_timer_block);
 706                 break;
 707
 708         case ACPI_REGISTER_SMI_COMMAND_BLOCK:   /* 8-bit access */
 709
 710                 /* SMI_CMD is currently always in IO space */
 711
 712                 status =
 713                     acpi_hw_write_port(acpi_gbl_FADT.smi_command, value, 8);
 714                 break;
 715
 716         default:
 717
 718                 ACPI_ERROR((AE_INFO, "Unknown Register ID: 0x%X", register_id));
 719                 status = AE_BAD_PARAMETER;
 720                 break;
 721         }
 722
 723 exit:
 724         return_ACPI_STATUS(status);
 725 }
 726
 727 /******************************************************************************
 728  *
 729  * FUNCTION:    acpi_hw_read_multiple
 730  *
 731  * PARAMETERS:  value               - Where the register value is returned
 732  *              register_a           - First ACPI register (required)
 733  *              register_b           - Second ACPI register (optional)
 734  *
 735  * RETURN:      Status
 736  *
 737  * DESCRIPTION: Read from the specified two-part ACPI register (such as PM1 A/B)
 738  *
 739  ******************************************************************************/
 740
 741 static acpi_status
 742 acpi_hw_read_multiple(u32 *value,
 743                       struct acpi_generic_address *register_a,
 744                       struct acpi_generic_address *register_b)
 745 {
 746         u32 value_a = 0;
 747         u32 value_b = 0;
 748         acpi_status status;
 749
 750         /* The first register is always required */
 751
 752         status = acpi_hw_read(&value_a, register_a);
 753         if (ACPI_FAILURE(status)) {
 754                 return (status);
 755         }
 756
 757         /* Second register is optional */
 758
 759         if (register_b->address) {
 760                 status = acpi_hw_read(&value_b, register_b);
 761                 if (ACPI_FAILURE(status)) {
 762                         return (status);
 763                 }
 764         }
 765
 766         /*
 767          * OR the two return values together. No shifting or masking is necessary,
 768          * because of how the PM1 registers are defined in the ACPI specification:
 769          *
 770          * "Although the bits can be split between the two register blocks (each
 771          * register block has a unique pointer within the FADT), the bit positions
 772          * are maintained. The register block with unimplemented bits (that is,
 773          * those implemented in the other register block) always returns zeros,
 774          * and writes have no side effects"
 775          */
 776         *value = (value_a | value_b);
 777         return (AE_OK);
 778 }
 779
 780 /******************************************************************************
 781  *
 782  * FUNCTION:    acpi_hw_write_multiple
 783  *
 784  * PARAMETERS:  value               - The value to write
 785  *              register_a           - First ACPI register (required)
 786  *              register_b           - Second ACPI register (optional)
 787  *
 788  * RETURN:      Status
 789  *
 790  * DESCRIPTION: Write to the specified two-part ACPI register (such as PM1 A/B)
 791  *
 792  ******************************************************************************/
 793
 794 static acpi_status
 795 acpi_hw_write_multiple(u32 value,
 796                        struct acpi_generic_address *register_a,
 797                        struct acpi_generic_address *register_b)
 798 {
 799         acpi_status status;
 800
 801         /* The first register is always required */
 802
 803         status = acpi_hw_write(value, register_a);
 804         if (ACPI_FAILURE(status)) {
 805                 return (status);
 806         }
 807
 808         /*
 809          * Second register is optional
 810          *
 811          * No bit shifting or clearing is necessary, because of how the PM1
 812          * registers are defined in the ACPI specification:
 813          *
 814          * "Although the bits can be split between the two register blocks (each
 815          * register block has a unique pointer within the FADT), the bit positions
 816          * are maintained. The register block with unimplemented bits (that is,
 817          * those implemented in the other register block) always returns zeros,
 818          * and writes have no side effects"
 819          */
 820         if (register_b->address) {
 821                 status = acpi_hw_write(value, register_b);
 822         }
 823
 824         return (status);
 825 }
 826
 827 #endif                          /* !ACPI_REDUCED_HARDWARE */