// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
/******************************************************************************
 *
 * Module Name: hwacpi - ACPI Hardware Initialization/Mode Interface
 *
 * Copyright (C) 2000 - 2025, Intel Corp.
 *
 *****************************************************************************/

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

#define _COMPONENT          ACPI_HARDWARE
ACPI_MODULE_NAME("hwacpi")

#if (!ACPI_REDUCED_HARDWARE)    /* Entire module */
/******************************************************************************
 *
 * FUNCTION:    acpi_hw_set_mode
 *
 * PARAMETERS:  mode            - SYS_MODE_ACPI or SYS_MODE_LEGACY
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Transitions the system into the requested mode.
 *
 ******************************************************************************/
acpi_status acpi_hw_set_mode(u32 mode)
{

        acpi_status status;

        ACPI_FUNCTION_TRACE(hw_set_mode);

        /* If the Hardware Reduced flag is set, machine is always in acpi mode */

        if (acpi_gbl_reduced_hardware) {
                return_ACPI_STATUS(AE_OK);
        }

        /*
         * ACPI 2.0 clarified that if SMI_CMD in FADT is zero,
         * system does not support mode transition.
         */
        if (!acpi_gbl_FADT.smi_command) {
                ACPI_ERROR((AE_INFO,
                            "No SMI_CMD in FADT, mode transition failed"));
                return_ACPI_STATUS(AE_NO_HARDWARE_RESPONSE);
        }

        /*
         * ACPI 2.0 clarified the meaning of ACPI_ENABLE and ACPI_DISABLE
         * in FADT: If it is zero, enabling or disabling is not supported.
         * As old systems may have used zero for mode transition,
         * we make sure both the numbers are zero to determine these
         * transitions are not supported.
         */
        if (!acpi_gbl_FADT.acpi_enable && !acpi_gbl_FADT.acpi_disable) {
                ACPI_ERROR((AE_INFO,
                            "No ACPI mode transition supported in this system "
                            "(enable/disable both zero)"));
                return_ACPI_STATUS(AE_OK);
        }

        switch (mode) {
        case ACPI_SYS_MODE_ACPI:

                /* BIOS should have disabled ALL fixed and GP events */

                status = acpi_hw_write_port(acpi_gbl_FADT.smi_command,
                                            (u32) acpi_gbl_FADT.acpi_enable, 8);
                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                                  "Attempting to enable ACPI mode\n"));
                break;

        case ACPI_SYS_MODE_LEGACY:
                /*
                 * BIOS should clear all fixed status bits and restore fixed event
                 * enable bits to default
                 */
                status = acpi_hw_write_port(acpi_gbl_FADT.smi_command,
                                            (u32)acpi_gbl_FADT.acpi_disable, 8);
                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                                  "Attempting to enable Legacy (non-ACPI) mode\n"));
                break;

        default:

                return_ACPI_STATUS(AE_BAD_PARAMETER);
        }

        if (ACPI_FAILURE(status)) {
                ACPI_EXCEPTION((AE_INFO, status,
                                "Could not write ACPI mode change"));
                return_ACPI_STATUS(status);
        }

        return_ACPI_STATUS(AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_hw_get_mode
 *
 * PARAMETERS:  none
 *
 * RETURN:      SYS_MODE_ACPI or SYS_MODE_LEGACY
 *
 * DESCRIPTION: Return current operating state of system. Determined by
 *              querying the SCI_EN bit.
 *
 ******************************************************************************/

u32 acpi_hw_get_mode(void)
{
        acpi_status status;
        u32 value;

        ACPI_FUNCTION_TRACE(hw_get_mode);

        /* If the Hardware Reduced flag is set, machine is always in acpi mode */

        if (acpi_gbl_reduced_hardware) {
                return_UINT32(ACPI_SYS_MODE_ACPI);
        }

        /*
         * ACPI 2.0 clarified that if SMI_CMD in FADT is zero,
         * system does not support mode transition.
         */
        if (!acpi_gbl_FADT.smi_command) {
                return_UINT32(ACPI_SYS_MODE_ACPI);
        }

        status = acpi_read_bit_register(ACPI_BITREG_SCI_ENABLE, &value);
        if (ACPI_FAILURE(status)) {
                return_UINT32(ACPI_SYS_MODE_LEGACY);
        }

        if (value) {
                return_UINT32(ACPI_SYS_MODE_ACPI);
        } else {
                return_UINT32(ACPI_SYS_MODE_LEGACY);
        }
}

#endif                          /* !ACPI_REDUCED_HARDWARE */