cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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hwacpi.c (3871B)

      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 - 2022, 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 */