ACPICA: Update for ACPI 5 hardware-reduced feature

Ensure that AcpiEnable and AcpiDisable work properly when the
hardware-reduced flag is set in the FADT.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

2 files changed, 24 insertions, 0 deletions

diff --git a/drivers/acpi/acpica/evxfevnt.c b/drivers/acpi/acpica/evxfevnt.c
index d6e4e42316db..7039606a0ba8 100644
--- a/drivers/acpi/acpica/evxfevnt.c
+++ b/drivers/acpi/acpica/evxfevnt.c
@@ -74,6 +74,12 @@ acpi_status acpi_enable(void)
                 return_ACPI_STATUS(AE_NO_ACPI_TABLES);
         }
 
+        /* If the Hardware Reduced flag is set, machine is always in acpi mode */
+
+        if (acpi_gbl_reduced_hardware) {
+                return_ACPI_STATUS(AE_OK);
+        }
+
         /* Check current mode */
 
         if (acpi_hw_get_mode() == ACPI_SYS_MODE_ACPI) {
@@ -126,6 +132,12 @@ acpi_status acpi_disable(void)
 
         ACPI_FUNCTION_TRACE(acpi_disable);
 
+        /* If the Hardware Reduced flag is set, machine is always in acpi mode */
+
+        if (acpi_gbl_reduced_hardware) {
+                return_ACPI_STATUS(AE_OK);
+        }
+
         if (acpi_hw_get_mode() == ACPI_SYS_MODE_LEGACY) {
                 ACPI_DEBUG_PRINT((ACPI_DB_INIT,
                                   "System is already in legacy (non-ACPI) mode\n"));
diff --git a/drivers/acpi/acpica/hwacpi.c b/drivers/acpi/acpica/hwacpi.c
index deb3f61e2bd1..9b02a9f5b04a 100644
--- a/drivers/acpi/acpica/hwacpi.c
+++ b/drivers/acpi/acpica/hwacpi.c
@@ -66,6 +66,12 @@ acpi_status acpi_hw_set_mode(u32 mode)
 
         ACPI_FUNCTION_TRACE(hw_set_mode);
 
+        /* If the Hardware Reduced flag is set, machine is always in acpi mode */
+
+        if (acpi_gbl_reduced_hardware) {
+                return_ACPI_STATUS(AE_OK);
+        }
+
         /*
          * ACPI 2.0 clarified that if SMI_CMD in FADT is zero,
          * system does not support mode transition.
@@ -146,6 +152,12 @@ u32 acpi_hw_get_mode(void)
 
         ACPI_FUNCTION_TRACE(hw_get_mode);
 
+        /* If the Hardware Reduced flag is set, machine is always in acpi mode */
+
+        if (acpi_gbl_reduced_hardware) {
+                return_VALUE(ACPI_SYS_MODE_ACPI);
+        }
+
         /*
          * ACPI 2.0 clarified that if SMI_CMD in FADT is zero,
          * system does not support mode transition.