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>
diff --git a/drivers/acpi/acpica/hwacpi.c b/drivers/acpi/acpica/hwacpi.c
index deb3f61..9b02a9f 100644
--- a/drivers/acpi/acpica/hwacpi.c
+++ b/drivers/acpi/acpica/hwacpi.c
@@ -66,6 +66,12 @@
 
 	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 @@
 
 	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.