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
  14 ACPI_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  ******************************************************************************/
  28 acpi_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
 114 u32 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 */