LXR linux/drivers/acpi/acpica/hwacpi.c

   1// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
   2/******************************************************************************
   3 *
   4 * Module Name: hwacpi - ACPI Hardware Initialization/Mode Interface
   5 *
   6 * Copyright (C) 2000 - 2020, Intel Corp.
   7 *
   8 *****************************************************************************/
   9
  10#include <acpi/acpi.h>
  11#include "accommon.h"
  12
  13#define _COMPONENT          ACPI_HARDWARE
  14ACPI_MODULE_NAME("hwacpi")
  15
  16#if (!ACPI_REDUCED_HARDWARE)    /* Entire module */
  17/******************************************************************************
  18 *
  19 * FUNCTION:    acpi_hw_set_mode
  20 *
  21 * PARAMETERS:  mode            - SYS_MODE_ACPI or SYS_MODE_LEGACY
  22 *
  23 * RETURN:      Status
  24 *
  25 * DESCRIPTION: Transitions the system into the requested mode.
  26 *
  27 ******************************************************************************/
  28acpi_status acpi_hw_set_mode(u32 mode)
  29{
  30
  31        acpi_status status;
  32
  33        ACPI_FUNCTION_TRACE(hw_set_mode);
  34
  35        /* If the Hardware Reduced flag is set, machine is always in acpi mode */
  36
  37        if (acpi_gbl_reduced_hardware) {
  38                return_ACPI_STATUS(AE_OK);
  39        }
  40
  41        /*
  42         * ACPI 2.0 clarified that if SMI_CMD in FADT is zero,
  43         * system does not support mode transition.
  44         */
  45        if (!acpi_gbl_FADT.smi_command) {
  46                ACPI_ERROR((AE_INFO,
  47                            "No SMI_CMD in FADT, mode transition failed"));
  48                return_ACPI_STATUS(AE_NO_HARDWARE_RESPONSE);
  49        }
  50
  51        /*
  52         * ACPI 2.0 clarified the meaning of ACPI_ENABLE and ACPI_DISABLE
  53         * in FADT: If it is zero, enabling or disabling is not supported.
  54         * As old systems may have used zero for mode transition,
  55         * we make sure both the numbers are zero to determine these
  56         * transitions are not supported.
  57         */
  58        if (!acpi_gbl_FADT.acpi_enable && !acpi_gbl_FADT.acpi_disable) {
  59                ACPI_ERROR((AE_INFO,
  60                            "No ACPI mode transition supported in this system "
  61                            "(enable/disable both zero)"));
  62                return_ACPI_STATUS(AE_OK);
  63        }
  64
  65        switch (mode) {
  66        case ACPI_SYS_MODE_ACPI:
  67
  68                /* BIOS should have disabled ALL fixed and GP events */
  69
  70                status = acpi_hw_write_port(acpi_gbl_FADT.smi_command,
  71                                            (u32) acpi_gbl_FADT.acpi_enable, 8);
  72                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
  73                                  "Attempting to enable ACPI mode\n"));
  74                break;
  75
  76        case ACPI_SYS_MODE_LEGACY:
  77                /*
  78                 * BIOS should clear all fixed status bits and restore fixed event
  79                 * enable bits to default
  80                 */
  81                status = acpi_hw_write_port(acpi_gbl_FADT.smi_command,
  82                                            (u32)acpi_gbl_FADT.acpi_disable, 8);
  83                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
  84                                  "Attempting to enable Legacy (non-ACPI) mode\n"));
  85                break;
  86
  87        default:
  88
  89                return_ACPI_STATUS(AE_BAD_PARAMETER);
  90        }
  91
  92        if (ACPI_FAILURE(status)) {
  93                ACPI_EXCEPTION((AE_INFO, status,
  94                                "Could not write ACPI mode change"));
  95                return_ACPI_STATUS(status);
  96        }
  97
  98        return_ACPI_STATUS(AE_OK);
  99}
 100
 101/*******************************************************************************
 102 *
 103 * FUNCTION:    acpi_hw_get_mode
 104 *
 105 * PARAMETERS:  none
 106 *
 107 * RETURN:      SYS_MODE_ACPI or SYS_MODE_LEGACY
 108 *
 109 * DESCRIPTION: Return current operating state of system. Determined by
 110 *              querying the SCI_EN bit.
 111 *
 112 ******************************************************************************/
 113
 114u32 acpi_hw_get_mode(void)
 115{
 116        acpi_status status;
 117        u32 value;
 118
 119        ACPI_FUNCTION_TRACE(hw_get_mode);
 120
 121        /* If the Hardware Reduced flag is set, machine is always in acpi mode */
 122
 123        if (acpi_gbl_reduced_hardware) {
 124                return_UINT32(ACPI_SYS_MODE_ACPI);
 125        }
 126
 127        /*
 128         * ACPI 2.0 clarified that if SMI_CMD in FADT is zero,
 129         * system does not support mode transition.
 130         */
 131        if (!acpi_gbl_FADT.smi_command) {
 132                return_UINT32(ACPI_SYS_MODE_ACPI);
 133        }
 134
 135        status = acpi_read_bit_register(ACPI_BITREG_SCI_ENABLE, &value);
 136        if (ACPI_FAILURE(status)) {
 137                return_UINT32(ACPI_SYS_MODE_LEGACY);
 138        }
 139
 140        if (value) {
 141                return_UINT32(ACPI_SYS_MODE_ACPI);
 142        } else {
 143                return_UINT32(ACPI_SYS_MODE_LEGACY);
 144        }
 145}
 146
 147#endif                          /* !ACPI_REDUCED_HARDWARE */
 148