ACPICA: Truncate I/O addresses to 16 bits for Windows compatibility

This feature is optional and is enabled if the BIOS requests any
Windows OSI strings. It can also be enabled by the host OS.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
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>

drivers/acpi/acpica/acglobal.h

@@ -125,6 +125,14 @@ u8 ACPI_INIT_GLOBAL(acpi_gbl_enable_aml_debug_object, FALSE);
  */
 u8 ACPI_INIT_GLOBAL(acpi_gbl_copy_dsdt_locally, FALSE);
 
+/*
+ * Optionally truncate I/O addresses to 16 bits. Provides compatibility
+ * with other ACPI implementations. NOTE: During ACPICA initialization,
+ * this value is set to TRUE if any Windows OSI strings have been
+ * requested by the BIOS.
+ */
+u8 ACPI_INIT_GLOBAL(acpi_gbl_truncate_io_addresses, FALSE);
+
 /* acpi_gbl_FADT is a local copy of the FADT, converted to a common format. */
 
 struct acpi_table_fadt acpi_gbl_FADT;

drivers/acpi/acpica/hwvalid.c

@@ -222,6 +222,12 @@ acpi_status acpi_hw_read_port(acpi_io_address address, u32 *value, u32 width)
 	u32 one_byte;
 	u32 i;
 
+	/* Truncate address to 16 bits if requested */
+
+	if (acpi_gbl_truncate_io_addresses) {
+		address &= ACPI_UINT16_MAX;
+	}
+
 	/* Validate the entire request and perform the I/O */
 
 	status = acpi_hw_validate_io_request(address, width);
@@ -279,6 +285,12 @@ acpi_status acpi_hw_write_port(acpi_io_address address, u32 value, u32 width)
 	acpi_status status;
 	u32 i;
 
+	/* Truncate address to 16 bits if requested */
+
+	if (acpi_gbl_truncate_io_addresses) {
+		address &= ACPI_UINT16_MAX;
+	}
+
 	/* Validate the entire request and perform the I/O */
 
 	status = acpi_hw_validate_io_request(address, width);

drivers/acpi/acpica/nsinit.c

@@ -193,6 +193,15 @@ acpi_status acpi_ns_initialize_devices(void)
 					acpi_ns_init_one_device, NULL, &info,
 					NULL);
 
+	/*
+	 * Any _OSI requests should be completed by now. If the BIOS has
+	 * requested any Windows OSI strings, we will always truncate
+	 * I/O addresses to 16 bits -- for Windows compatibility.
+	 */
+	if (acpi_gbl_osi_data >= ACPI_OSI_WIN_2000) {
+		acpi_gbl_truncate_io_addresses = TRUE;
+	}
+
 	ACPI_FREE(info.evaluate_info);
 	if (ACPI_FAILURE(status)) {
 		goto error_exit;

include/acpi/acpixf.h

@@ -69,6 +69,7 @@ extern acpi_name acpi_gbl_trace_method_name;
 extern u32 acpi_gbl_trace_flags;
 extern u8 acpi_gbl_enable_aml_debug_object;
 extern u8 acpi_gbl_copy_dsdt_locally;
+extern u8 acpi_gbl_truncate_io_addresses;
 
 extern u32 acpi_current_gpe_count;
 extern struct acpi_table_fadt acpi_gbl_FADT;