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