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         u8 access_width;
 315         u32 bit_width;
 316         u8 bit_offset;
 317         u64 value64;
 318         u32 new_value32, old_value32;
 319         u8 index;
 320         acpi_status status;
 321
 322         ACPI_FUNCTION_NAME(hw_write);
 323
 324         /* Validate contents of the GAS register */
 325
 326         status = acpi_hw_validate_register(reg, 32, &address);
 327         if (ACPI_FAILURE(status)) {
 328                 return (status);
 329         }
 330
 331         /* Convert access_width into number of bits based */
 332
 333         access_width = acpi_hw_get_access_bit_width(reg, 32);
 334         bit_width = reg->bit_offset + reg->bit_width;
 335         bit_offset = reg->bit_offset;
 336
 337         /*
 338          * Two address spaces supported: Memory or IO. PCI_Config is
 339          * not supported here because the GAS structure is insufficient
 340          */
 341         index = 0;
 342         while (bit_width) {
 343                 /*
 344                  * Use offset style bit reads because "Index * AccessWidth" is
 345                  * ensured to be less than 32-bits by acpi_hw_validate_register().
 346                  */
 347                 new_value32 = ACPI_GET_BITS(&value, index * access_width,
 348                                             ACPI_MASK_BITS_ABOVE_32
 349                                             (access_width));
 350
 351                 if (bit_offset >= access_width) {
 352                         bit_offset -= access_width;
 353                 } else {
 354                         /*
 355                          * Use offset style bit masks because access_width is ensured
 356                          * to be less than 32-bits by acpi_hw_validate_register() and
 357                          * bit_offset/bit_width is less than access_width here.
 358                          */
 359                         if (bit_offset) {
 360                                 new_value32 &= ACPI_MASK_BITS_BELOW(bit_offset);
 361                         }
 362                         if (bit_width < access_width) {
 363                                 new_value32 &= ACPI_MASK_BITS_ABOVE(bit_width);
 364                         }
 365
 366                         if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
 367                                 if (bit_offset || bit_width < access_width) {
 368                                         /*
 369                                          * Read old values in order not to modify the bits that
 370                                          * are beyond the register bit_width/bit_offset setting.
 371                                          */
 372                                         status =
 373                                             acpi_os_read_memory((acpi_physical_address)
 374                                                                 address +
 375                                                                 index *
 376                                                                 ACPI_DIV_8
 377                                                                 (access_width),
 378                                                                 &value64,
 379                                                                 access_width);
 380                                         old_value32 = (u32)value64;
 381
 382                                         /*
 383                                          * Use offset style bit masks because access_width is
 384                                          * ensured to be less than 32-bits by
 385                                          * acpi_hw_validate_register() and bit_offset/bit_width is
 386                                          * less than access_width here.
 387                                          */
 388                                         if (bit_offset) {
 389                                                 old_value32 &=
 390                                                     ACPI_MASK_BITS_ABOVE
 391                                                     (bit_offset);
 392                                                 bit_offset = 0;
 393                                         }
 394                                         if (bit_width < access_width) {
 395                                                 old_value32 &=
 396                                                     ACPI_MASK_BITS_BELOW
 397                                                     (bit_width);
 398                                         }
 399
 400                                         new_value32 |= old_value32;
 401                                 }
 402
 403                                 value64 = (u64)new_value32;
 404                                 status =
 405                                     acpi_os_write_memory((acpi_physical_address)
 406                                                          address +
 407                                                          index *
 408                                                          ACPI_DIV_8
 409                                                          (access_width),
 410                                                          value64, access_width);
 411                         } else {        /* ACPI_ADR_SPACE_SYSTEM_IO, validated earlier */
 412
 413                                 if (bit_offset || bit_width < access_width) {
 414                                         /*
 415                                          * Read old values in order not to modify the bits that
 416                                          * are beyond the register bit_width/bit_offset setting.
 417                                          */
 418                                         status =
 419                                             acpi_hw_read_port((acpi_io_address)
 420                                                               address +
 421                                                               index *
 422                                                               ACPI_DIV_8
 423                                                               (access_width),
 424                                                               &old_value32,
 425                                                               access_width);
 426
 427                                         /*
 428                                          * Use offset style bit masks because access_width is
 429                                          * ensured to be less than 32-bits by
 430                                          * acpi_hw_validate_register() and bit_offset/bit_width is
 431                                          * less than access_width here.
 432                                          */
 433                                         if (bit_offset) {
 434                                                 old_value32 &=
 435                                                     ACPI_MASK_BITS_ABOVE
 436                                                     (bit_offset);
 437                                                 bit_offset = 0;
 438                                         }
 439                                         if (bit_width < access_width) {
 440                                                 old_value32 &=
 441                                                     ACPI_MASK_BITS_BELOW
 442                                                     (bit_width);
 443                                         }
 444
 445                                         new_value32 |= old_value32;
 446                                 }
 447
 448                                 status = acpi_hw_write_port((acpi_io_address)
 449                                                             address +
 450                                                             index *
 451                                                             ACPI_DIV_8
 452                                                             (access_width),
 453                                                             new_value32,
 454                                                             access_width);
 455                         }
 456                 }
 457
 458                 /*
 459                  * Index * access_width is ensured to be less than 32-bits by
 460                  * acpi_hw_validate_register().
 461                  */
 462                 bit_width -=
 463                     bit_width > access_width ? access_width : bit_width;
 464                 index++;
 465         }
 466
 467         ACPI_DEBUG_PRINT((ACPI_DB_IO,
 468                           "Wrote: %8.8X width %2d   to %8.8X%8.8X (%s)\n",
 469                           value, access_width, ACPI_FORMAT_UINT64(address),
 470                           acpi_ut_get_region_name(reg->space_id)));
 471
 472         return (status);
 473 }
 474
 475 #if (!ACPI_REDUCED_HARDWARE)
 476 /*******************************************************************************
 477  *
 478  * FUNCTION:    acpi_hw_clear_acpi_status
 479  *
 480  * PARAMETERS:  None
 481  *
 482  * RETURN:      Status
 483  *
 484  * DESCRIPTION: Clears all fixed and general purpose status bits
 485  *
 486  ******************************************************************************/
 487
 488 acpi_status acpi_hw_clear_acpi_status(void)
 489 {
 490         acpi_status status;
 491         acpi_cpu_flags lock_flags = 0;
 492
 493         ACPI_FUNCTION_TRACE(hw_clear_acpi_status);
 494
 495         ACPI_DEBUG_PRINT((ACPI_DB_IO, "About to write %04X to %8.8X%8.8X\n",
 496                           ACPI_BITMASK_ALL_FIXED_STATUS,
 497                           ACPI_FORMAT_UINT64(acpi_gbl_xpm1a_status.address)));
 498
 499         lock_flags = acpi_os_acquire_lock(acpi_gbl_hardware_lock);
 500
 501         /* Clear the fixed events in PM1 A/B */
 502
 503         status = acpi_hw_register_write(ACPI_REGISTER_PM1_STATUS,
 504                                         ACPI_BITMASK_ALL_FIXED_STATUS);
 505
 506         acpi_os_release_lock(acpi_gbl_hardware_lock, lock_flags);
 507
 508         if (ACPI_FAILURE(status)) {
 509                 goto exit;
 510         }
 511
 512         /* Clear the GPE Bits in all GPE registers in all GPE blocks */
 513
 514         status = acpi_ev_walk_gpe_list(acpi_hw_clear_gpe_block, NULL);
 515
 516 exit:
 517         return_ACPI_STATUS(status);
 518 }
 519
 520 /*******************************************************************************
 521  *
 522  * FUNCTION:    acpi_hw_get_bit_register_info
 523  *
 524  * PARAMETERS:  register_id         - Index of ACPI Register to access
 525  *
 526  * RETURN:      The bitmask to be used when accessing the register
 527  *
 528  * DESCRIPTION: Map register_id into a register bitmask.
 529  *
 530  ******************************************************************************/
 531
 532 struct acpi_bit_register_info *acpi_hw_get_bit_register_info(u32 register_id)
 533 {
 534         ACPI_FUNCTION_ENTRY();
 535
 536         if (register_id > ACPI_BITREG_MAX) {
 537                 ACPI_ERROR((AE_INFO, "Invalid BitRegister ID: 0x%X",
 538                             register_id));
 539                 return (NULL);
 540         }
 541
 542         return (&acpi_gbl_bit_register_info[register_id]);
 543 }
 544
 545 /******************************************************************************
 546  *
 547  * FUNCTION:    acpi_hw_write_pm1_control
 548  *
 549  * PARAMETERS:  pm1a_control        - Value to be written to PM1A control
 550  *              pm1b_control        - Value to be written to PM1B control
 551  *
 552  * RETURN:      Status
 553  *
 554  * DESCRIPTION: Write the PM1 A/B control registers. These registers are
 555  *              different than than the PM1 A/B status and enable registers
 556  *              in that different values can be written to the A/B registers.
 557  *              Most notably, the SLP_TYP bits can be different, as per the
 558  *              values returned from the _Sx predefined methods.
 559  *
 560  ******************************************************************************/
 561
 562 acpi_status acpi_hw_write_pm1_control(u32 pm1a_control, u32 pm1b_control)
 563 {
 564         acpi_status status;
 565
 566         ACPI_FUNCTION_TRACE(hw_write_pm1_control);
 567
 568         status =
 569             acpi_hw_write(pm1a_control, &acpi_gbl_FADT.xpm1a_control_block);
 570         if (ACPI_FAILURE(status)) {
 571                 return_ACPI_STATUS(status);
 572         }
 573
 574         if (acpi_gbl_FADT.xpm1b_control_block.address) {
 575                 status =
 576                     acpi_hw_write(pm1b_control,
 577                                   &acpi_gbl_FADT.xpm1b_control_block);
 578         }
 579         return_ACPI_STATUS(status);
 580 }
 581
 582 /******************************************************************************
 583  *
 584  * FUNCTION:    acpi_hw_register_read
 585  *
 586  * PARAMETERS:  register_id         - ACPI Register ID
 587  *              return_value        - Where the register value is returned
 588  *
 589  * RETURN:      Status and the value read.
 590  *
 591  * DESCRIPTION: Read from the specified ACPI register
 592  *
 593  ******************************************************************************/
 594 acpi_status acpi_hw_register_read(u32 register_id, u32 *return_value)
 595 {
 596         u32 value = 0;
 597         acpi_status status;
 598
 599         ACPI_FUNCTION_TRACE(hw_register_read);
 600
 601         switch (register_id) {
 602         case ACPI_REGISTER_PM1_STATUS:  /* PM1 A/B: 16-bit access each */
 603
 604                 status = acpi_hw_read_multiple(&value,
 605                                                &acpi_gbl_xpm1a_status,
 606                                                &acpi_gbl_xpm1b_status);
 607                 break;
 608
 609         case ACPI_REGISTER_PM1_ENABLE:  /* PM1 A/B: 16-bit access each */
 610
 611                 status = acpi_hw_read_multiple(&value,
 612                                                &acpi_gbl_xpm1a_enable,
 613                                                &acpi_gbl_xpm1b_enable);
 614                 break;
 615
 616         case ACPI_REGISTER_PM1_CONTROL: /* PM1 A/B: 16-bit access each */
 617
 618                 status = acpi_hw_read_multiple(&value,
 619                                                &acpi_gbl_FADT.
 620                                                xpm1a_control_block,
 621                                                &acpi_gbl_FADT.
 622                                                xpm1b_control_block);
 623
 624                 /*
 625                  * Zero the write-only bits. From the ACPI specification, "Hardware
 626                  * Write-Only Bits": "Upon reads to registers with write-only bits,
 627                  * software masks out all write-only bits."
 628                  */
 629                 value &= ~ACPI_PM1_CONTROL_WRITEONLY_BITS;
 630                 break;
 631
 632         case ACPI_REGISTER_PM2_CONTROL: /* 8-bit access */
 633
 634                 status =
 635                     acpi_hw_read(&value, &acpi_gbl_FADT.xpm2_control_block);
 636                 break;
 637
 638         case ACPI_REGISTER_PM_TIMER:    /* 32-bit access */
 639
 640                 status = acpi_hw_read(&value, &acpi_gbl_FADT.xpm_timer_block);
 641                 break;
 642
 643         case ACPI_REGISTER_SMI_COMMAND_BLOCK:   /* 8-bit access */
 644
 645                 status =
 646                     acpi_hw_read_port(acpi_gbl_FADT.smi_command, &value, 8);
 647                 break;
 648
 649         default:
 650
 651                 ACPI_ERROR((AE_INFO, "Unknown Register ID: 0x%X", register_id));
 652                 status = AE_BAD_PARAMETER;
 653                 break;
 654         }
 655
 656         if (ACPI_SUCCESS(status)) {
 657                 *return_value = value;
 658         }
 659
 660         return_ACPI_STATUS(status);
 661 }
 662
 663 /******************************************************************************
 664  *
 665  * FUNCTION:    acpi_hw_register_write
 666  *
 667  * PARAMETERS:  register_id         - ACPI Register ID
 668  *              value               - The value to write
 669  *
 670  * RETURN:      Status
 671  *
 672  * DESCRIPTION: Write to the specified ACPI register
 673  *
 674  * NOTE: In accordance with the ACPI specification, this function automatically
 675  * preserves the value of the following bits, meaning that these bits cannot be
 676  * changed via this interface:
 677  *
 678  * PM1_CONTROL[0] = SCI_EN
 679  * PM1_CONTROL[9]
 680  * PM1_STATUS[11]
 681  *
 682  * ACPI References:
 683  * 1) Hardware Ignored Bits: When software writes to a register with ignored
 684  *      bit fields, it preserves the ignored bit fields
 685  * 2) SCI_EN: OSPM always preserves this bit position
 686  *
 687  ******************************************************************************/
 688
 689 acpi_status acpi_hw_register_write(u32 register_id, u32 value)
 690 {
 691         acpi_status status;
 692         u32 read_value;
 693
 694         ACPI_FUNCTION_TRACE(hw_register_write);
 695
 696         switch (register_id) {
 697         case ACPI_REGISTER_PM1_STATUS:  /* PM1 A/B: 16-bit access each */
 698                 /*
 699                  * Handle the "ignored" bit in PM1 Status. According to the ACPI
 700                  * specification, ignored bits are to be preserved when writing.
 701                  * Normally, this would mean a read/modify/write sequence. However,
 702                  * preserving a bit in the status register is different. Writing a
 703                  * one clears the status, and writing a zero preserves the status.
 704                  * Therefore, we must always write zero to the ignored bit.
 705                  *
 706                  * This behavior is clarified in the ACPI 4.0 specification.
 707                  */
 708                 value &= ~ACPI_PM1_STATUS_PRESERVED_BITS;
 709
 710                 status = acpi_hw_write_multiple(value,
 711                                                 &acpi_gbl_xpm1a_status,
 712                                                 &acpi_gbl_xpm1b_status);
 713                 break;
 714
 715         case ACPI_REGISTER_PM1_ENABLE:  /* PM1 A/B: 16-bit access each */
 716
 717                 status = acpi_hw_write_multiple(value,
 718                                                 &acpi_gbl_xpm1a_enable,
 719                                                 &acpi_gbl_xpm1b_enable);
 720                 break;
 721
 722         case ACPI_REGISTER_PM1_CONTROL: /* PM1 A/B: 16-bit access each */
 723                 /*
 724                  * Perform a read first to preserve certain bits (per ACPI spec)
 725                  * Note: This includes SCI_EN, we never want to change this bit
 726                  */
 727                 status = acpi_hw_read_multiple(&read_value,
 728                                                &acpi_gbl_FADT.
 729                                                xpm1a_control_block,
 730                                                &acpi_gbl_FADT.
 731                                                xpm1b_control_block);
 732                 if (ACPI_FAILURE(status)) {
 733                         goto exit;
 734                 }
 735
 736                 /* Insert the bits to be preserved */
 737
 738                 ACPI_INSERT_BITS(value, ACPI_PM1_CONTROL_PRESERVED_BITS,
 739                                  read_value);
 740
 741                 /* Now we can write the data */
 742
 743                 status = acpi_hw_write_multiple(value,
 744                                                 &acpi_gbl_FADT.
 745                                                 xpm1a_control_block,
 746                                                 &acpi_gbl_FADT.
 747                                                 xpm1b_control_block);
 748                 break;
 749
 750         case ACPI_REGISTER_PM2_CONTROL: /* 8-bit access */
 751                 /*
 752                  * For control registers, all reserved bits must be preserved,
 753                  * as per the ACPI spec.
 754                  */
 755                 status =
 756                     acpi_hw_read(&read_value,
 757                                  &acpi_gbl_FADT.xpm2_control_block);
 758                 if (ACPI_FAILURE(status)) {
 759                         goto exit;
 760                 }
 761
 762                 /* Insert the bits to be preserved */
 763
 764                 ACPI_INSERT_BITS(value, ACPI_PM2_CONTROL_PRESERVED_BITS,
 765                                  read_value);
 766
 767                 status =
 768                     acpi_hw_write(value, &acpi_gbl_FADT.xpm2_control_block);
 769                 break;
 770
 771         case ACPI_REGISTER_PM_TIMER:    /* 32-bit access */
 772
 773                 status = acpi_hw_write(value, &acpi_gbl_FADT.xpm_timer_block);
 774                 break;
 775
 776         case ACPI_REGISTER_SMI_COMMAND_BLOCK:   /* 8-bit access */
 777
 778                 /* SMI_CMD is currently always in IO space */
 779
 780                 status =
 781                     acpi_hw_write_port(acpi_gbl_FADT.smi_command, value, 8);
 782                 break;
 783
 784         default:
 785
 786                 ACPI_ERROR((AE_INFO, "Unknown Register ID: 0x%X", register_id));
 787                 status = AE_BAD_PARAMETER;
 788                 break;
 789         }
 790
 791 exit:
 792         return_ACPI_STATUS(status);
 793 }
 794
 795 /******************************************************************************
 796  *
 797  * FUNCTION:    acpi_hw_read_multiple
 798  *
 799  * PARAMETERS:  value               - Where the register value is returned
 800  *              register_a           - First ACPI register (required)
 801  *              register_b           - Second ACPI register (optional)
 802  *
 803  * RETURN:      Status
 804  *
 805  * DESCRIPTION: Read from the specified two-part ACPI register (such as PM1 A/B)
 806  *
 807  ******************************************************************************/
 808
 809 static acpi_status
 810 acpi_hw_read_multiple(u32 *value,
 811                       struct acpi_generic_address *register_a,
 812                       struct acpi_generic_address *register_b)
 813 {
 814         u32 value_a = 0;
 815         u32 value_b = 0;
 816         acpi_status status;
 817
 818         /* The first register is always required */
 819
 820         status = acpi_hw_read(&value_a, register_a);
 821         if (ACPI_FAILURE(status)) {
 822                 return (status);
 823         }
 824
 825         /* Second register is optional */
 826
 827         if (register_b->address) {
 828                 status = acpi_hw_read(&value_b, register_b);
 829                 if (ACPI_FAILURE(status)) {
 830                         return (status);
 831                 }
 832         }
 833
 834         /*
 835          * OR the two return values together. No shifting or masking is necessary,
 836          * because of how the PM1 registers are defined in the ACPI specification:
 837          *
 838          * "Although the bits can be split between the two register blocks (each
 839          * register block has a unique pointer within the FADT), the bit positions
 840          * are maintained. The register block with unimplemented bits (that is,
 841          * those implemented in the other register block) always returns zeros,
 842          * and writes have no side effects"
 843          */
 844         *value = (value_a | value_b);
 845         return (AE_OK);
 846 }
 847
 848 /******************************************************************************
 849  *
 850  * FUNCTION:    acpi_hw_write_multiple
 851  *
 852  * PARAMETERS:  value               - The value to write
 853  *              register_a           - First ACPI register (required)
 854  *              register_b           - Second ACPI register (optional)
 855  *
 856  * RETURN:      Status
 857  *
 858  * DESCRIPTION: Write to the specified two-part ACPI register (such as PM1 A/B)
 859  *
 860  ******************************************************************************/
 861
 862 static acpi_status
 863 acpi_hw_write_multiple(u32 value,
 864                        struct acpi_generic_address *register_a,
 865                        struct acpi_generic_address *register_b)
 866 {
 867         acpi_status status;
 868
 869         /* The first register is always required */
 870
 871         status = acpi_hw_write(value, register_a);
 872         if (ACPI_FAILURE(status)) {
 873                 return (status);
 874         }
 875
 876         /*
 877          * Second register is optional
 878          *
 879          * No bit shifting or clearing is necessary, because of how the PM1
 880          * registers are defined in the ACPI specification:
 881          *
 882          * "Although the bits can be split between the two register blocks (each
 883          * register block has a unique pointer within the FADT), the bit positions
 884          * are maintained. The register block with unimplemented bits (that is,
 885          * those implemented in the other register block) always returns zeros,
 886          * and writes have no side effects"
 887          */
 888         if (register_b->address) {
 889                 status = acpi_hw_write(value, register_b);
 890         }
 891
 892         return (status);
 893 }
 894
 895 #endif                          /* !ACPI_REDUCED_HARDWARE */