ACPICA: Update for field unit access

Mostly for access to Generic Serial Bus, but also cleanup
for the other fields.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Erik Schmauss <erik.schmauss@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpica/acinterp.h

@@ -123,6 +123,9 @@ acpi_ex_trace_point(acpi_trace_event_type type,
 /*
  * exfield - ACPI AML (p-code) execution - field manipulation
  */
+acpi_status
+acpi_ex_get_protocol_buffer_length(u32 protocol_id, u32 *return_length);
+
 acpi_status
 acpi_ex_common_buffer_setup(union acpi_operand_object *obj_desc,
 			    u32 buffer_length, u32 * datum_count);

include/acpi/acconfig.h

@@ -173,12 +173,20 @@
 #define ACPI_RSDP_CHECKSUM_LENGTH       20
 #define ACPI_RSDP_XCHECKSUM_LENGTH      36
 
-/* SMBus, GSBus and IPMI bidirectional buffer size */
+/*
+ * SMBus, GSBus and IPMI buffer sizes. All have a 2-byte header,
+ * containing both Status and Length.
+ */
+#define ACPI_SERIAL_HEADER_SIZE         2	/* Common for below. Status and Length fields */
+
+#define ACPI_SMBUS_DATA_SIZE            32
+#define ACPI_SMBUS_BUFFER_SIZE          ACPI_SERIAL_HEADER_SIZE + ACPI_SMBUS_DATA_SIZE
+
+#define ACPI_IPMI_DATA_SIZE             64
+#define ACPI_IPMI_BUFFER_SIZE           ACPI_SERIAL_HEADER_SIZE + ACPI_IPMI_DATA_SIZE
 
-#define ACPI_SMBUS_BUFFER_SIZE          34
-#define ACPI_IPMI_BUFFER_SIZE           66
-#define ACPI_GSBUS_BUFFER_SIZE          34	/* Not clear if this is needed */
-#define ACPI_MAX_GSBUS_BUFFER_SIZE      255	/* Worst-case bidirectional buffer */
+#define ACPI_MAX_GSBUS_DATA_SIZE        255
+#define ACPI_MAX_GSBUS_BUFFER_SIZE      ACPI_SERIAL_HEADER_SIZE + ACPI_MAX_GSBUS_DATA_SIZE
 
 /* _sx_d and _sx_w control methods */