/******************************************************************************
 *
 * Module Name: tbfadt   - FADT table utilities
 *
 *****************************************************************************/

/*
 * Copyright (C) 2000 - 2013, Intel Corp.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    substantially similar to the "NO WARRANTY" disclaimer below
 *    ("Disclaimer") and any redistribution must be conditioned upon
 *    including a substantially similar Disclaimer requirement for further
 *    binary redistribution.
 * 3. Neither the names of the above-listed copyright holders nor the names
 *    of any contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * NO WARRANTY
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 */

#include <acpi/acpi.h>
#include "accommon.h"
#include "actables.h"

#define _COMPONENT          ACPI_TABLES
ACPI_MODULE_NAME("tbfadt")

/* Local prototypes */
static void
acpi_tb_init_generic_address(struct acpi_generic_address *generic_address,
                             u8 space_id,
                             u8 byte_width, u64 address, char *register_name);

static void acpi_tb_convert_fadt(void);

static void acpi_tb_validate_fadt(void);

static void acpi_tb_setup_fadt_registers(void);

/* Table for conversion of FADT to common internal format and FADT validation */

typedef struct acpi_fadt_info {
        char *name;
        u16 address64;
        u16 address32;
        u16 length;
        u8 default_length;
        u8 type;

} acpi_fadt_info;

#define ACPI_FADT_OPTIONAL          0
#define ACPI_FADT_REQUIRED          1
#define ACPI_FADT_SEPARATE_LENGTH   2

static struct acpi_fadt_info fadt_info_table[] = {
        {"Pm1aEventBlock",
         ACPI_FADT_OFFSET(xpm1a_event_block),
         ACPI_FADT_OFFSET(pm1a_event_block),
         ACPI_FADT_OFFSET(pm1_event_length),
         ACPI_PM1_REGISTER_WIDTH * 2,   /* Enable + Status register */
         ACPI_FADT_REQUIRED},

        {"Pm1bEventBlock",
         ACPI_FADT_OFFSET(xpm1b_event_block),
         ACPI_FADT_OFFSET(pm1b_event_block),
         ACPI_FADT_OFFSET(pm1_event_length),
         ACPI_PM1_REGISTER_WIDTH * 2,   /* Enable + Status register */
         ACPI_FADT_OPTIONAL},

        {"Pm1aControlBlock",
         ACPI_FADT_OFFSET(xpm1a_control_block),
         ACPI_FADT_OFFSET(pm1a_control_block),
         ACPI_FADT_OFFSET(pm1_control_length),
         ACPI_PM1_REGISTER_WIDTH,
         ACPI_FADT_REQUIRED},

        {"Pm1bControlBlock",
         ACPI_FADT_OFFSET(xpm1b_control_block),
         ACPI_FADT_OFFSET(pm1b_control_block),
         ACPI_FADT_OFFSET(pm1_control_length),
         ACPI_PM1_REGISTER_WIDTH,
         ACPI_FADT_OPTIONAL},

        {"Pm2ControlBlock",
         ACPI_FADT_OFFSET(xpm2_control_block),
         ACPI_FADT_OFFSET(pm2_control_block),
         ACPI_FADT_OFFSET(pm2_control_length),
         ACPI_PM2_REGISTER_WIDTH,
         ACPI_FADT_SEPARATE_LENGTH},

        {"PmTimerBlock",
         ACPI_FADT_OFFSET(xpm_timer_block),
         ACPI_FADT_OFFSET(pm_timer_block),
         ACPI_FADT_OFFSET(pm_timer_length),
         ACPI_PM_TIMER_WIDTH,
         ACPI_FADT_REQUIRED},

        {"Gpe0Block",
         ACPI_FADT_OFFSET(xgpe0_block),
         ACPI_FADT_OFFSET(gpe0_block),
         ACPI_FADT_OFFSET(gpe0_block_length),
         0,
         ACPI_FADT_SEPARATE_LENGTH},

        {"Gpe1Block",
         ACPI_FADT_OFFSET(xgpe1_block),
         ACPI_FADT_OFFSET(gpe1_block),
         ACPI_FADT_OFFSET(gpe1_block_length),
         0,
         ACPI_FADT_SEPARATE_LENGTH}
};

#define ACPI_FADT_INFO_ENTRIES \
                        (sizeof (fadt_info_table) / sizeof (struct acpi_fadt_info))

/* Table used to split Event Blocks into separate status/enable registers */

typedef struct acpi_fadt_pm_info {
        struct acpi_generic_address *target;
        u16 source;
        u8 register_num;

} acpi_fadt_pm_info;

static struct acpi_fadt_pm_info fadt_pm_info_table[] = {
        {&acpi_gbl_xpm1a_status,
         ACPI_FADT_OFFSET(xpm1a_event_block),
         0},

        {&acpi_gbl_xpm1a_enable,
         ACPI_FADT_OFFSET(xpm1a_event_block),
         1},

        {&acpi_gbl_xpm1b_status,
         ACPI_FADT_OFFSET(xpm1b_event_block),
         0},

        {&acpi_gbl_xpm1b_enable,
         ACPI_FADT_OFFSET(xpm1b_event_block),
         1}
};

#define ACPI_FADT_PM_INFO_ENTRIES \
                        (sizeof (fadt_pm_info_table) / sizeof (struct acpi_fadt_pm_info))

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_init_generic_address
 *
 * PARAMETERS:  generic_address     - GAS struct to be initialized
 *              space_id            - ACPI Space ID for this register
 *              byte_width          - Width of this register
 *              address             - Address of the register
 *
 * RETURN:      None
 *
 * DESCRIPTION: Initialize a Generic Address Structure (GAS)
 *              See the ACPI specification for a full description and
 *              definition of this structure.
 *
 ******************************************************************************/

static void
acpi_tb_init_generic_address(struct acpi_generic_address *generic_address,
                             u8 space_id,
                             u8 byte_width, u64 address, char *register_name)
{
        u8 bit_width;

        /* Bit width field in the GAS is only one byte long, 255 max */

        bit_width = (u8)(byte_width * 8);

        if (byte_width > 31) {  /* (31*8)=248 */
                ACPI_ERROR((AE_INFO,
                            "%s - 32-bit FADT register is too long (%u bytes, %u bits) "
                            "to convert to GAS struct - 255 bits max, truncating",
                            register_name, byte_width, (byte_width * 8)));

                bit_width = 255;
        }

        /*
         * The 64-bit Address field is non-aligned in the byte packed
         * GAS struct.
         */
        ACPI_MOVE_64_TO_64(&generic_address->address, &address);

        /* All other fields are byte-wide */

        generic_address->space_id = space_id;
        generic_address->bit_width = bit_width;
        generic_address->bit_offset = 0;
        generic_address->access_width = 0;      /* Access width ANY */
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_parse_fadt
 *
 * PARAMETERS:  table_index         - Index for the FADT
 *
 * RETURN:      None
 *
 * DESCRIPTION: Initialize the FADT, DSDT and FACS tables
 *              (FADT contains the addresses of the DSDT and FACS)
 *
 ******************************************************************************/

void acpi_tb_parse_fadt(u32 table_index)
{
        u32 length;
        struct acpi_table_header *table;

        /*
         * The FADT has multiple versions with different lengths,
         * and it contains pointers to both the DSDT and FACS tables.
         *
         * Get a local copy of the FADT and convert it to a common format
         * Map entire FADT, assumed to be smaller than one page.
         */
        length = acpi_gbl_root_table_list.tables[table_index].length;

        table =
            acpi_os_map_memory(acpi_gbl_root_table_list.tables[table_index].
                               address, length);
        if (!table) {
                return;
        }

        /*
         * Validate the FADT checksum before we copy the table. Ignore
         * checksum error as we want to try to get the DSDT and FACS.
         */
        (void)acpi_tb_verify_checksum(table, length);

        /* Create a local copy of the FADT in common ACPI 2.0+ format */

        acpi_tb_create_local_fadt(table, length);

        /* All done with the real FADT, unmap it */

        acpi_os_unmap_memory(table, length);

        /* Obtain the DSDT and FACS tables via their addresses within the FADT */

        acpi_tb_install_table((acpi_physical_address) acpi_gbl_FADT.Xdsdt,
                              ACPI_SIG_DSDT, ACPI_TABLE_INDEX_DSDT);

        /* If Hardware Reduced flag is set, there is no FACS */

        if (!acpi_gbl_reduced_hardware) {
                acpi_tb_install_table((acpi_physical_address) acpi_gbl_FADT.
                                      Xfacs, ACPI_SIG_FACS,
                                      ACPI_TABLE_INDEX_FACS);
        }
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_create_local_fadt
 *
 * PARAMETERS:  table               - Pointer to BIOS FADT
 *              length              - Length of the table
 *
 * RETURN:      None
 *
 * DESCRIPTION: Get a local copy of the FADT and convert it to a common format.
 *              Performs validation on some important FADT fields.
 *
 * NOTE:        We create a local copy of the FADT regardless of the version.
 *
 ******************************************************************************/

void acpi_tb_create_local_fadt(struct acpi_table_header *table, u32 length)
{
        /*
         * Check if the FADT is larger than the largest table that we expect
         * (the ACPI 5.0 version). If so, truncate the table, and issue
         * a warning.
         */
        if (length > sizeof(struct acpi_table_fadt)) {
                ACPI_BIOS_WARNING((AE_INFO,
                                   "FADT (revision %u) is longer than ACPI 5.0 version, "
                                   "truncating length %u to %u",
                                   table->revision, length,
                                   (u32)sizeof(struct acpi_table_fadt)));
        }

        /* Clear the entire local FADT */

        ACPI_MEMSET(&acpi_gbl_FADT, 0, sizeof(struct acpi_table_fadt));

        /* Copy the original FADT, up to sizeof (struct acpi_table_fadt) */

        ACPI_MEMCPY(&acpi_gbl_FADT, table,
                    ACPI_MIN(length, sizeof(struct acpi_table_fadt)));

        /* Take a copy of the Hardware Reduced flag */

        acpi_gbl_reduced_hardware = FALSE;
        if (acpi_gbl_FADT.flags & ACPI_FADT_HW_REDUCED) {
                acpi_gbl_reduced_hardware = TRUE;
        }

        /* Convert the local copy of the FADT to the common internal format */

        acpi_tb_convert_fadt();

        /* Validate FADT values now, before we make any changes */

        acpi_tb_validate_fadt();

        /* Initialize the global ACPI register structures */

        acpi_tb_setup_fadt_registers();
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_convert_fadt
 *
 * PARAMETERS:  None, uses acpi_gbl_FADT
 *
 * RETURN:      None
 *
 * DESCRIPTION: Converts all versions of the FADT to a common internal format.
 *              Expand 32-bit addresses to 64-bit as necessary.
 *
 * NOTE:        acpi_gbl_FADT must be of size (struct acpi_table_fadt),
 *              and must contain a copy of the actual FADT.
 *
 * Notes on 64-bit register addresses:
 *
 * After this FADT conversion, later ACPICA code will only use the 64-bit "X"
 * fields of the FADT for all ACPI register addresses.
 *
 * The 64-bit "X" fields are optional extensions to the original 32-bit FADT
 * V1.0 fields. Even if they are present in the FADT, they are optional and
 * are unused if the BIOS sets them to zero. Therefore, we must copy/expand
 * 32-bit V1.0 fields if the corresponding X field is zero.
 *
 * For ACPI 1.0 FADTs, all 32-bit address fields are expanded to the
 * corresponding "X" fields in the internal FADT.
 *
 * For ACPI 2.0+ FADTs, all valid (non-zero) 32-bit address fields are expanded
 * to the corresponding 64-bit X fields. For compatibility with other ACPI
 * implementations, we ignore the 64-bit field if the 32-bit field is valid,
 * regardless of whether the host OS is 32-bit or 64-bit.
 *
 ******************************************************************************/

static void acpi_tb_convert_fadt(void)
{
        struct acpi_generic_address *address64;
        u32 address32;
        u32 i;

        /*
         * Expand the 32-bit FACS and DSDT addresses to 64-bit as necessary.
         * Later code will always use the X 64-bit field. Also, check for an
         * address mismatch between the 32-bit and 64-bit address fields
         * (FIRMWARE_CTRL/X_FIRMWARE_CTRL, DSDT/X_DSDT) which would indicate
         * the presence of two FACS or two DSDT tables.
         */
        if (!acpi_gbl_FADT.Xfacs) {
                acpi_gbl_FADT.Xfacs = (u64) acpi_gbl_FADT.facs;
        } else if (acpi_gbl_FADT.facs &&
                   (acpi_gbl_FADT.Xfacs != (u64) acpi_gbl_FADT.facs)) {
                ACPI_WARNING((AE_INFO,
                    "32/64 FACS address mismatch in FADT - two FACS tables!"));
        }

        if (!acpi_gbl_FADT.Xdsdt) {
                acpi_gbl_FADT.Xdsdt = (u64) acpi_gbl_FADT.dsdt;
        } else if (acpi_gbl_FADT.dsdt &&
                   (acpi_gbl_FADT.Xdsdt != (u64) acpi_gbl_FADT.dsdt)) {
                ACPI_WARNING((AE_INFO,
                    "32/64 DSDT address mismatch in FADT - two DSDT tables!"));
        }

        /*
         * For ACPI 1.0 FADTs (revision 1 or 2), ensure that reserved fields which
         * should be zero are indeed zero. This will workaround BIOSs that
         * inadvertently place values in these fields.
         *
         * The ACPI 1.0 reserved fields that will be zeroed are the bytes located
         * at offset 45, 55, 95, and the word located at offset 109, 110.
         *
         * Note: The FADT revision value is unreliable. Only the length can be
         * trusted.
         */
        if (acpi_gbl_FADT.header.length <= ACPI_FADT_V2_SIZE) {
                acpi_gbl_FADT.preferred_profile = 0;
                acpi_gbl_FADT.pstate_control = 0;
                acpi_gbl_FADT.cst_control = 0;
                acpi_gbl_FADT.boot_flags = 0;
        }

        /* Update the local FADT table header length */

        acpi_gbl_FADT.header.length = sizeof(struct acpi_table_fadt);

        /*
         * Expand the ACPI 1.0 32-bit addresses to the ACPI 2.0 64-bit "X"
         * generic address structures as necessary. Later code will always use
         * the 64-bit address structures.
         *
         * March 2009:
         * We now always use the 32-bit address if it is valid (non-null). This
         * is not in accordance with the ACPI specification which states that
         * the 64-bit address supersedes the 32-bit version, but we do this for
         * compatibility with other ACPI implementations. Most notably, in the
         * case where both the 32 and 64 versions are non-null, we use the 32-bit
         * version. This is the only address that is guaranteed to have been
         * tested by the BIOS manufacturer.
         */
        for (i = 0; i < ACPI_FADT_INFO_ENTRIES; i++) {
                address32 = *ACPI_ADD_PTR(u32,
                                          &acpi_gbl_FADT,
                                          fadt_info_table[i].address32);

                address64 = ACPI_ADD_PTR(struct acpi_generic_address,
                                         &acpi_gbl_FADT,
                                         fadt_info_table[i].address64);

                /*
                 * If both 32- and 64-bit addresses are valid (non-zero),
                 * they must match.
                 */
                if (address64->address && address32 &&
                    (address64->address != (u64)address32)) {
                        ACPI_BIOS_ERROR((AE_INFO,
                                         "32/64X address mismatch in FADT/%s: "
                                         "0x%8.8X/0x%8.8X%8.8X, using 32",
                                         fadt_info_table[i].name, address32,
                                         ACPI_FORMAT_UINT64(address64->
                                                            address)));
                }

                /* Always use 32-bit address if it is valid (non-null) */

                if (address32) {
                        /*
                         * Copy the 32-bit address to the 64-bit GAS structure. The
                         * Space ID is always I/O for 32-bit legacy address fields
                        */
                        acpi_tb_init_generic_address(address64,
                                                     ACPI_ADR_SPACE_SYSTEM_IO,
                                                     *ACPI_ADD_PTR(u8,
                                                                   &acpi_gbl_FADT,
                                                                   fadt_info_table
                                                                   [i].length),
                                                     (u64) address32,
                                                     fadt_info_table[i].name);
                }
        }
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_validate_fadt
 *
 * PARAMETERS:  table           - Pointer to the FADT to be validated
 *
 * RETURN:      None
 *
 * DESCRIPTION: Validate various important fields within the FADT. If a problem
 *              is found, issue a message, but no status is returned.
 *              Used by both the table manager and the disassembler.
 *
 * Possible additional checks:
 * (acpi_gbl_FADT.pm1_event_length >= 4)
 * (acpi_gbl_FADT.pm1_control_length >= 2)
 * (acpi_gbl_FADT.pm_timer_length >= 4)
 * Gpe block lengths must be multiple of 2
 *
 ******************************************************************************/

static void acpi_tb_validate_fadt(void)
{
        char *name;
        struct acpi_generic_address *address64;
        u8 length;
        u32 i;

        /*
         * Check for FACS and DSDT address mismatches. An address mismatch between
         * the 32-bit and 64-bit address fields (FIRMWARE_CTRL/X_FIRMWARE_CTRL and
         * DSDT/X_DSDT) would indicate the presence of two FACS or two DSDT tables.
         */
        if (acpi_gbl_FADT.facs &&
            (acpi_gbl_FADT.Xfacs != (u64)acpi_gbl_FADT.facs)) {
                ACPI_BIOS_WARNING((AE_INFO,
                                   "32/64X FACS address mismatch in FADT - "
                                   "0x%8.8X/0x%8.8X%8.8X, using 32",
                                   acpi_gbl_FADT.facs,
                                   ACPI_FORMAT_UINT64(acpi_gbl_FADT.Xfacs)));

                acpi_gbl_FADT.Xfacs = (u64)acpi_gbl_FADT.facs;
        }

        if (acpi_gbl_FADT.dsdt &&
            (acpi_gbl_FADT.Xdsdt != (u64)acpi_gbl_FADT.dsdt)) {
                ACPI_BIOS_WARNING((AE_INFO,
                                   "32/64X DSDT address mismatch in FADT - "
                                   "0x%8.8X/0x%8.8X%8.8X, using 32",
                                   acpi_gbl_FADT.dsdt,
                                   ACPI_FORMAT_UINT64(acpi_gbl_FADT.Xdsdt)));

                acpi_gbl_FADT.Xdsdt = (u64)acpi_gbl_FADT.dsdt;
        }

        /* If Hardware Reduced flag is set, we are all done */

        if (acpi_gbl_reduced_hardware) {
                return;
        }

        /* Examine all of the 64-bit extended address fields (X fields) */

        for (i = 0; i < ACPI_FADT_INFO_ENTRIES; i++) {
                /*
                 * Generate pointer to the 64-bit address, get the register
                 * length (width) and the register name
                 */
                address64 = ACPI_ADD_PTR(struct acpi_generic_address,
                                         &acpi_gbl_FADT,
                                         fadt_info_table[i].address64);
                length =
                    *ACPI_ADD_PTR(u8, &acpi_gbl_FADT,
                                  fadt_info_table[i].length);
                name = fadt_info_table[i].name;

                /*
                 * For each extended field, check for length mismatch between the
                 * legacy length field and the corresponding 64-bit X length field.
                 * Note: If the legacy length field is > 0xFF bits, ignore this
                 * check. (GPE registers can be larger than the 64-bit GAS structure
                 * can accomodate, 0xFF bits).
                 */
                if (address64->address &&
                    (ACPI_MUL_8(length) <= ACPI_UINT8_MAX) &&
                    (address64->bit_width != ACPI_MUL_8(length))) {
                        ACPI_BIOS_WARNING((AE_INFO,
                                           "32/64X length mismatch in FADT/%s: %u/%u",
                                           name, ACPI_MUL_8(length),
                                           address64->bit_width));
                }

                if (fadt_info_table[i].type & ACPI_FADT_REQUIRED) {
                        /*
                         * Field is required (Pm1a_event, Pm1a_control, pm_timer).
                         * Both the address and length must be non-zero.
                         */
                        if (!address64->address || !length) {
                                ACPI_BIOS_ERROR((AE_INFO,
                                                 "Required FADT field %s has zero address and/or length: "
                                                 "0x%8.8X%8.8X/0x%X",
                                                 name,
                                                 ACPI_FORMAT_UINT64(address64->
                                                                    address),
                                                 length));
                        }
                } else if (fadt_info_table[i].type & ACPI_FADT_SEPARATE_LENGTH) {
                        /*
                         * Field is optional (Pm2_control, GPE0, GPE1) AND has its own
                         * length field. If present, both the address and length must
                         * be valid.
                         */
                        if ((address64->address && !length) ||
                            (!address64->address && length)) {
                                ACPI_BIOS_WARNING((AE_INFO,
                                                   "Optional FADT field %s has zero address or length: "
                                                   "0x%8.8X%8.8X/0x%X",
                                                   name,
                                                   ACPI_FORMAT_UINT64
                                                   (address64->address),
                                                   length));
                        }
                }
        }
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_setup_fadt_registers
 *
 * PARAMETERS:  None, uses acpi_gbl_FADT.
 *
 * RETURN:      None
 *
 * DESCRIPTION: Initialize global ACPI PM1 register definitions. Optionally,
 *              force FADT register definitions to their default lengths.
 *
 ******************************************************************************/

static void acpi_tb_setup_fadt_registers(void)
{
        struct acpi_generic_address *target64;
        struct acpi_generic_address *source64;
        u8 pm1_register_byte_width;
        u32 i;

        /*
         * Optionally check all register lengths against the default values and
         * update them if they are incorrect.
         */
        if (acpi_gbl_use_default_register_widths) {
                for (i = 0; i < ACPI_FADT_INFO_ENTRIES; i++) {
                        target64 =
                            ACPI_ADD_PTR(struct acpi_generic_address,
                                         &acpi_gbl_FADT,
                                         fadt_info_table[i].address64);

                        /*
                         * If a valid register (Address != 0) and the (default_length > 0)
                         * (Not a GPE register), then check the width against the default.
                         */
                        if ((target64->address) &&
                            (fadt_info_table[i].default_length > 0) &&
                            (fadt_info_table[i].default_length !=
                             target64->bit_width)) {
                                ACPI_BIOS_WARNING((AE_INFO,
                                                   "Invalid length for FADT/%s: %u, using default %u",
                                                   fadt_info_table[i].name,
                                                   target64->bit_width,
                                                   fadt_info_table[i].
                                                   default_length));

                                /* Incorrect size, set width to the default */

                                target64->bit_width =
                                    fadt_info_table[i].default_length;
                        }
                }
        }

        /*
         * Get the length of the individual PM1 registers (enable and status).
         * Each register is defined to be (event block length / 2). Extra divide
         * by 8 converts bits to bytes.
         */
        pm1_register_byte_width = (u8)
            ACPI_DIV_16(acpi_gbl_FADT.xpm1a_event_block.bit_width);

        /*
         * Calculate separate GAS structs for the PM1x (A/B) Status and Enable
         * registers. These addresses do not appear (directly) in the FADT, so it
         * is useful to pre-calculate them from the PM1 Event Block definitions.
         *
         * The PM event blocks are split into two register blocks, first is the
         * PM Status Register block, followed immediately by the PM Enable
         * Register block. Each is of length (pm1_event_length/2)
         *
         * Note: The PM1A event block is required by the ACPI specification.
         * However, the PM1B event block is optional and is rarely, if ever,
         * used.
         */

        for (i = 0; i < ACPI_FADT_PM_INFO_ENTRIES; i++) {
                source64 =
                    ACPI_ADD_PTR(struct acpi_generic_address, &acpi_gbl_FADT,
                                 fadt_pm_info_table[i].source);

                if (source64->address) {
                        acpi_tb_init_generic_address(fadt_pm_info_table[i].
                                                     target, source64->space_id,
                                                     pm1_register_byte_width,
                                                     source64->address +
                                                     (fadt_pm_info_table[i].
                                                      register_num *
                                                      pm1_register_byte_width),
                                                     "PmRegisters");
                }
        }
}