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 - 2019, 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 */