ACPI 5.0: Implement hardware-reduced option

If HW-reduced flag is set in the FADT, do not attempt to access
or initialize any ACPI hardware, including SCI and global lock.
No FACS will be present.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 20 insertions, 2 deletions

diff --git a/drivers/acpi/acpica/tbfadt.c b/drivers/acpi/acpica/tbfadt.c
index 536fd2bc7a47..1e1a7de34439 100644
--- a/drivers/acpi/acpica/tbfadt.c
+++ b/drivers/acpi/acpica/tbfadt.c
@@ -253,8 +253,13 @@ void acpi_tb_parse_fadt(u32 table_index)
         acpi_tb_install_table((acpi_physical_address) acpi_gbl_FADT.Xdsdt,
                               ACPI_SIG_DSDT, ACPI_TABLE_INDEX_DSDT);
 
-        acpi_tb_install_table((acpi_physical_address) acpi_gbl_FADT.Xfacs,
-                              ACPI_SIG_FACS, ACPI_TABLE_INDEX_FACS);
+        /* If Hardware Reduced flag is set, there is no FACS */
+
+        if (!acpi_gbl_reduced_hardware) {
+                acpi_tb_install_table((acpi_physical_address) acpi_gbl_FADT.
+                                      Xfacs, ACPI_SIG_FACS,
+                                      ACPI_TABLE_INDEX_FACS);
+        }
 }
 
 /*******************************************************************************
@@ -297,6 +302,13 @@ void acpi_tb_create_local_fadt(struct acpi_table_header *table, u32 length)
         ACPI_MEMCPY(&acpi_gbl_FADT, table,
                     ACPI_MIN(length, sizeof(struct acpi_table_fadt)));
 
+        /* Take a copy of the Hardware Reduced flag */
+
+        acpi_gbl_reduced_hardware = FALSE;
+        if (acpi_gbl_FADT.flags & ACPI_FADT_HW_REDUCED) {
+                acpi_gbl_reduced_hardware = TRUE;
+        }
+
         /* Convert the local copy of the FADT to the common internal format */
 
         acpi_tb_convert_fadt();
@@ -502,6 +514,12 @@ static void acpi_tb_validate_fadt(void)
                 acpi_gbl_FADT.Xdsdt = (u64) acpi_gbl_FADT.dsdt;
         }
 
+        /* If Hardware Reduced flag is set, we are all done */
+
+        if (acpi_gbl_reduced_hardware) {
+                return;
+        }
+
         /* Examine all of the 64-bit extended address fields (X fields) */
 
         for (i = 0; i < ACPI_FADT_INFO_ENTRIES; i++) {