ACPICA: Split large interpreter file

New file: exserial.c

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/Makefile

@@ -65,6 +65,7 @@ acpi-y +=		\
 	exresnte.o	\
 	exresolv.o	\
 	exresop.o	\
+	exserial.o	\
 	exstore.o	\
 	exstoren.o	\
 	exstorob.o	\

drivers/acpi/acpica/acinterp.h

@@ -270,6 +270,26 @@ acpi_ex_prep_common_field_object(union acpi_operand_object *obj_desc,
 
 acpi_status acpi_ex_prep_field_value(struct acpi_create_field_info *info);
 
+/*
+ * exserial - field_unit support for serial address spaces
+ */
+acpi_status
+acpi_ex_read_serial_bus(union acpi_operand_object *obj_desc,
+			union acpi_operand_object **return_buffer);
+
+acpi_status
+acpi_ex_write_serial_bus(union acpi_operand_object *source_desc,
+			 union acpi_operand_object *obj_desc,
+			 union acpi_operand_object **return_buffer);
+
+acpi_status
+acpi_ex_read_gpio(union acpi_operand_object *obj_desc, void *buffer);
+
+acpi_status
+acpi_ex_write_gpio(union acpi_operand_object *source_desc,
+		   union acpi_operand_object *obj_desc,
+		   union acpi_operand_object **return_buffer);
+
 /*
  * exsystem - Interface to OS services
  */

drivers/acpi/acpica/exfield.c

@@ -16,31 +16,12 @@
 #define _COMPONENT          ACPI_EXECUTER
 ACPI_MODULE_NAME("exfield")
 
-/* Local prototypes */
-static acpi_status
-acpi_ex_read_serial_bus(union acpi_operand_object *obj_desc,
-			union acpi_operand_object **return_buffer);
-
-static acpi_status
-acpi_ex_write_serial_bus(union acpi_operand_object *source_desc,
-			 union acpi_operand_object *obj_desc,
-			 union acpi_operand_object **return_buffer);
-
-static acpi_status
-acpi_ex_read_gpio(union acpi_operand_object *obj_desc, void *buffer);
-
-static acpi_status
-acpi_ex_write_gpio(union acpi_operand_object *source_desc,
-		   union acpi_operand_object *obj_desc,
-		   union acpi_operand_object **return_buffer);
-
 /*
  * This table maps the various Attrib protocols to the byte transfer
  * length. Used for the generic serial bus.
  */
 #define ACPI_INVALID_PROTOCOL_ID        0x80
 #define ACPI_MAX_PROTOCOL_ID            0x0F
-
 const u8 acpi_protocol_lengths[] = {
 	ACPI_INVALID_PROTOCOL_ID,	/* 0 - reserved */
 	ACPI_INVALID_PROTOCOL_ID,	/* 1 - reserved */
@@ -343,348 +324,3 @@ acpi_ex_write_data_to_field(union acpi_operand_object *source_desc,
 	acpi_ex_release_global_lock(obj_desc->common_field.field_flags);
 	return_ACPI_STATUS(status);
 }
-
-/*******************************************************************************
- *
- * FUNCTION:    acpi_ex_read_gpio
- *
- * PARAMETERS:  obj_desc            - The named field to read
- *              buffer              - Where the return data is returnd
- *
- * RETURN:      Status
- *
- * DESCRIPTION: Read from a named field that references a Generic Serial Bus
- *              field
- *
- ******************************************************************************/
-
-static acpi_status
-acpi_ex_read_gpio(union acpi_operand_object *obj_desc, void *buffer)
-{
-	acpi_status status;
-
-	ACPI_FUNCTION_TRACE_PTR(ex_read_gpio, obj_desc);
-
-	/*
-	 * For GPIO (general_purpose_io), the Address will be the bit offset
-	 * from the previous Connection() operator, making it effectively a
-	 * pin number index. The bit_length is the length of the field, which
-	 * is thus the number of pins.
-	 */
-	ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
-			  "GPIO FieldRead [FROM]:  Pin %u Bits %u\n",
-			  obj_desc->field.pin_number_index,
-			  obj_desc->field.bit_length));
-
-	/* Lock entire transaction if requested */
-
-	acpi_ex_acquire_global_lock(obj_desc->common_field.field_flags);
-
-	/* Perform the read */
-
-	status = acpi_ex_access_region(obj_desc, 0, (u64 *)buffer, ACPI_READ);
-
-	acpi_ex_release_global_lock(obj_desc->common_field.field_flags);
-	return_ACPI_STATUS(status);
-}
-
-/*******************************************************************************
- *
- * FUNCTION:    acpi_ex_write_gpio
- *
- * PARAMETERS:  source_desc         - Contains data to write. Expect to be
- *                                    an Integer object.
- *              obj_desc            - The named field
- *              result_desc         - Where the return value is returned, if any
- *
- * RETURN:      Status
- *
- * DESCRIPTION: Write to a named field that references a General Purpose I/O
- *              field.
- *
- ******************************************************************************/
-
-static acpi_status
-acpi_ex_write_gpio(union acpi_operand_object *source_desc,
-		   union acpi_operand_object *obj_desc,
-		   union acpi_operand_object **return_buffer)
-{
-	acpi_status status;
-	void *buffer;
-
-	ACPI_FUNCTION_TRACE_PTR(ex_write_gpio, obj_desc);
-
-	/*
-	 * For GPIO (general_purpose_io), we will bypass the entire field
-	 * mechanism and handoff the bit address and bit width directly to
-	 * the handler. The Address will be the bit offset
-	 * from the previous Connection() operator, making it effectively a
-	 * pin number index. The bit_length is the length of the field, which
-	 * is thus the number of pins.
-	 */
-	if (source_desc->common.type != ACPI_TYPE_INTEGER) {
-		return_ACPI_STATUS(AE_AML_OPERAND_TYPE);
-	}
-
-	ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
-			  "GPIO FieldWrite [FROM]: (%s:%X), Value %.8X  [TO]: Pin %u Bits %u\n",
-			  acpi_ut_get_type_name(source_desc->common.type),
-			  source_desc->common.type,
-			  (u32)source_desc->integer.value,
-			  obj_desc->field.pin_number_index,
-			  obj_desc->field.bit_length));
-
-	buffer = &source_desc->integer.value;
-
-	/* Lock entire transaction if requested */
-
-	acpi_ex_acquire_global_lock(obj_desc->common_field.field_flags);
-
-	/* Perform the write */
-
-	status = acpi_ex_access_region(obj_desc, 0, (u64 *)buffer, ACPI_WRITE);
-	acpi_ex_release_global_lock(obj_desc->common_field.field_flags);
-	return_ACPI_STATUS(status);
-}
-
-/*******************************************************************************
- *
- * FUNCTION:    acpi_ex_read_serial_bus
- *
- * PARAMETERS:  obj_desc            - The named field to read
- *              return_buffer       - Where the return value is returned, if any
- *
- * RETURN:      Status
- *
- * DESCRIPTION: Read from a named field that references a serial bus
- *              (SMBus, IPMI, or GSBus).
- *
- ******************************************************************************/
-
-static acpi_status
-acpi_ex_read_serial_bus(union acpi_operand_object *obj_desc,
-			union acpi_operand_object **return_buffer)
-{
-	acpi_status status;
-	u32 buffer_length;
-	union acpi_operand_object *buffer_desc;
-	u32 function;
-	u16 accessor_type;
-
-	ACPI_FUNCTION_TRACE_PTR(ex_read_serial_bus, obj_desc);
-
-	/*
-	 * This is an SMBus, GSBus or IPMI read. We must create a buffer to
-	 * hold the data and then directly access the region handler.
-	 *
-	 * Note: SMBus and GSBus protocol value is passed in upper 16-bits
-	 * of Function
-	 *
-	 * Common buffer format:
-	 *     Status;    (Byte 0 of the data buffer)
-	 *     Length;    (Byte 1 of the data buffer)
-	 *     Data[x-1]: (Bytes 2-x of the arbitrary length data buffer)
-	 */
-	switch (obj_desc->field.region_obj->region.space_id) {
-	case ACPI_ADR_SPACE_SMBUS:
-
-		buffer_length = ACPI_SMBUS_BUFFER_SIZE;
-		function = ACPI_READ | (obj_desc->field.attribute << 16);
-		break;
-
-	case ACPI_ADR_SPACE_IPMI:
-
-		buffer_length = ACPI_IPMI_BUFFER_SIZE;
-		function = ACPI_READ;
-		break;
-
-	case ACPI_ADR_SPACE_GSBUS:
-
-		accessor_type = obj_desc->field.attribute;
-		if (accessor_type == AML_FIELD_ATTRIB_RAW_PROCESS_BYTES) {
-			ACPI_ERROR((AE_INFO,
-				    "Invalid direct read using bidirectional write-then-read protocol"));
-
-			return_ACPI_STATUS(AE_AML_PROTOCOL);
-		}
-
-		status =
-		    acpi_ex_get_protocol_buffer_length(accessor_type,
-						       &buffer_length);
-		if (ACPI_FAILURE(status)) {
-			ACPI_ERROR((AE_INFO,
-				    "Invalid protocol ID for GSBus: 0x%4.4X",
-				    accessor_type));
-
-			return_ACPI_STATUS(status);
-		}
-
-		/* Add header length to get the full size of the buffer */
-
-		buffer_length += ACPI_SERIAL_HEADER_SIZE;
-		function = ACPI_READ | (accessor_type << 16);
-		break;
-
-	default:
-		return_ACPI_STATUS(AE_AML_INVALID_SPACE_ID);
-	}
-
-	/* Create the local transfer buffer that is returned to the caller */
-
-	buffer_desc = acpi_ut_create_buffer_object(buffer_length);
-	if (!buffer_desc) {
-		return_ACPI_STATUS(AE_NO_MEMORY);
-	}
-
-	/* Lock entire transaction if requested */
-
-	acpi_ex_acquire_global_lock(obj_desc->common_field.field_flags);
-
-	/* Call the region handler for the write-then-read */
-
-	status = acpi_ex_access_region(obj_desc, 0,
-				       ACPI_CAST_PTR(u64,
-						     buffer_desc->buffer.
-						     pointer), function);
-	acpi_ex_release_global_lock(obj_desc->common_field.field_flags);
-
-	*return_buffer = buffer_desc;
-	return_ACPI_STATUS(status);
-}
-
-/*******************************************************************************
- *
- * FUNCTION:    acpi_ex_write_serial_bus
- *
- * PARAMETERS:  source_desc         - Contains data to write
- *              obj_desc            - The named field
- *              return_buffer       - Where the return value is returned, if any
- *
- * RETURN:      Status
- *
- * DESCRIPTION: Write to a named field that references a serial bus
- *              (SMBus, IPMI, GSBus).
- *
- ******************************************************************************/
-
-static acpi_status
-acpi_ex_write_serial_bus(union acpi_operand_object *source_desc,
-			 union acpi_operand_object *obj_desc,
-			 union acpi_operand_object **return_buffer)
-{
-	acpi_status status;
-	u32 buffer_length;
-	u32 data_length;
-	void *buffer;
-	union acpi_operand_object *buffer_desc;
-	u32 function;
-	u16 accessor_type;
-
-	ACPI_FUNCTION_TRACE_PTR(ex_write_serial_bus, obj_desc);
-
-	/*
-	 * This is an SMBus, GSBus or IPMI write. We will bypass the entire
-	 * field mechanism and handoff the buffer directly to the handler.
-	 * For these address spaces, the buffer is bidirectional; on a
-	 * write, return data is returned in the same buffer.
-	 *
-	 * Source must be a buffer of sufficient size, these are fixed size:
-	 * ACPI_SMBUS_BUFFER_SIZE, or ACPI_IPMI_BUFFER_SIZE.
-	 *
-	 * Note: SMBus and GSBus protocol type is passed in upper 16-bits
-	 * of Function
-	 *
-	 * Common buffer format:
-	 *     Status;    (Byte 0 of the data buffer)
-	 *     Length;    (Byte 1 of the data buffer)
-	 *     Data[x-1]: (Bytes 2-x of the arbitrary length data buffer)
-	 */
-	if (source_desc->common.type != ACPI_TYPE_BUFFER) {
-		ACPI_ERROR((AE_INFO,
-			    "SMBus/IPMI/GenericSerialBus write requires "
-			    "Buffer, found type %s",
-			    acpi_ut_get_object_type_name(source_desc)));
-
-		return_ACPI_STATUS(AE_AML_OPERAND_TYPE);
-	}
-
-	switch (obj_desc->field.region_obj->region.space_id) {
-	case ACPI_ADR_SPACE_SMBUS:
-
-		buffer_length = ACPI_SMBUS_BUFFER_SIZE;
-		data_length = ACPI_SMBUS_DATA_SIZE;
-		function = ACPI_WRITE | (obj_desc->field.attribute << 16);
-		break;
-
-	case ACPI_ADR_SPACE_IPMI:
-
-		buffer_length = ACPI_IPMI_BUFFER_SIZE;
-		data_length = ACPI_IPMI_DATA_SIZE;
-		function = ACPI_WRITE;
-		break;
-
-	case ACPI_ADR_SPACE_GSBUS:
-
-		accessor_type = obj_desc->field.attribute;
-		status =
-		    acpi_ex_get_protocol_buffer_length(accessor_type,
-						       &buffer_length);
-		if (ACPI_FAILURE(status)) {
-			ACPI_ERROR((AE_INFO,
-				    "Invalid protocol ID for GSBus: 0x%4.4X",
-				    accessor_type));
-
-			return_ACPI_STATUS(status);
-		}
-
-		/* Add header length to get the full size of the buffer */
-
-		buffer_length += ACPI_SERIAL_HEADER_SIZE;
-		data_length = source_desc->buffer.pointer[1];
-		function = ACPI_WRITE | (accessor_type << 16);
-		break;
-
-	default:
-		return_ACPI_STATUS(AE_AML_INVALID_SPACE_ID);
-	}
-
-#if 0
-	OBSOLETE ?
-	    /* Check for possible buffer overflow */
-	    if (data_length > source_desc->buffer.length) {
-		ACPI_ERROR((AE_INFO,
-			    "Length in buffer header (%u)(%u) is greater than "
-			    "the physical buffer length (%u) and will overflow",
-			    data_length, buffer_length,
-			    source_desc->buffer.length));
-
-		return_ACPI_STATUS(AE_AML_BUFFER_LIMIT);
-	}
-#endif
-
-	/* Create the transfer/bidirectional/return buffer */
-
-	buffer_desc = acpi_ut_create_buffer_object(buffer_length);
-	if (!buffer_desc) {
-		return_ACPI_STATUS(AE_NO_MEMORY);
-	}
-
-	/* Copy the input buffer data to the transfer buffer */
-
-	buffer = buffer_desc->buffer.pointer;
-	memcpy(buffer, source_desc->buffer.pointer, data_length);
-
-	/* Lock entire transaction if requested */
-
-	acpi_ex_acquire_global_lock(obj_desc->common_field.field_flags);
-
-	/*
-	 * Perform the write (returns status and perhaps data in the
-	 * same buffer)
-	 */
-	status = acpi_ex_access_region(obj_desc, 0, (u64 *)buffer, function);
-	acpi_ex_release_global_lock(obj_desc->common_field.field_flags);
-
-	*return_buffer = buffer_desc;
-	return_ACPI_STATUS(status);
-}

drivers/acpi/acpica/exserial.c

@@ -0,0 +1,360 @@
+// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
+/******************************************************************************
+ *
+ * Module Name: exserial - field_unit support for serial address spaces
+ *
+ * Copyright (C) 2000 - 2018, Intel Corp.
+ *
+ *****************************************************************************/
+
+#include <acpi/acpi.h>
+#include "accommon.h"
+#include "acdispat.h"
+#include "acinterp.h"
+#include "amlcode.h"
+
+#define _COMPONENT          ACPI_EXECUTER
+ACPI_MODULE_NAME("exserial")
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ex_read_gpio
+ *
+ * PARAMETERS:  obj_desc            - The named field to read
+ *              buffer              - Where the return data is returnd
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Read from a named field that references a Generic Serial Bus
+ *              field
+ *
+ ******************************************************************************/
+acpi_status acpi_ex_read_gpio(union acpi_operand_object *obj_desc, void *buffer)
+{
+	acpi_status status;
+
+	ACPI_FUNCTION_TRACE_PTR(ex_read_gpio, obj_desc);
+
+	/*
+	 * For GPIO (general_purpose_io), the Address will be the bit offset
+	 * from the previous Connection() operator, making it effectively a
+	 * pin number index. The bit_length is the length of the field, which
+	 * is thus the number of pins.
+	 */
+	ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
+			  "GPIO FieldRead [FROM]:  Pin %u Bits %u\n",
+			  obj_desc->field.pin_number_index,
+			  obj_desc->field.bit_length));
+
+	/* Lock entire transaction if requested */
+
+	acpi_ex_acquire_global_lock(obj_desc->common_field.field_flags);
+
+	/* Perform the read */
+
+	status = acpi_ex_access_region(obj_desc, 0, (u64 *)buffer, ACPI_READ);
+
+	acpi_ex_release_global_lock(obj_desc->common_field.field_flags);
+	return_ACPI_STATUS(status);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ex_write_gpio
+ *
+ * PARAMETERS:  source_desc         - Contains data to write. Expect to be
+ *                                    an Integer object.
+ *              obj_desc            - The named field
+ *              result_desc         - Where the return value is returned, if any
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Write to a named field that references a General Purpose I/O
+ *              field.
+ *
+ ******************************************************************************/
+
+acpi_status
+acpi_ex_write_gpio(union acpi_operand_object *source_desc,
+		   union acpi_operand_object *obj_desc,
+		   union acpi_operand_object **return_buffer)
+{
+	acpi_status status;
+	void *buffer;
+
+	ACPI_FUNCTION_TRACE_PTR(ex_write_gpio, obj_desc);
+
+	/*
+	 * For GPIO (general_purpose_io), we will bypass the entire field
+	 * mechanism and handoff the bit address and bit width directly to
+	 * the handler. The Address will be the bit offset
+	 * from the previous Connection() operator, making it effectively a
+	 * pin number index. The bit_length is the length of the field, which
+	 * is thus the number of pins.
+	 */
+	if (source_desc->common.type != ACPI_TYPE_INTEGER) {
+		return_ACPI_STATUS(AE_AML_OPERAND_TYPE);
+	}
+
+	ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
+			  "GPIO FieldWrite [FROM]: (%s:%X), Value %.8X  [TO]: Pin %u Bits %u\n",
+			  acpi_ut_get_type_name(source_desc->common.type),
+			  source_desc->common.type,
+			  (u32)source_desc->integer.value,
+			  obj_desc->field.pin_number_index,
+			  obj_desc->field.bit_length));
+
+	buffer = &source_desc->integer.value;
+
+	/* Lock entire transaction if requested */
+
+	acpi_ex_acquire_global_lock(obj_desc->common_field.field_flags);
+
+	/* Perform the write */
+
+	status = acpi_ex_access_region(obj_desc, 0, (u64 *)buffer, ACPI_WRITE);
+	acpi_ex_release_global_lock(obj_desc->common_field.field_flags);
+	return_ACPI_STATUS(status);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ex_read_serial_bus
+ *
+ * PARAMETERS:  obj_desc            - The named field to read
+ *              return_buffer       - Where the return value is returned, if any
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Read from a named field that references a serial bus
+ *              (SMBus, IPMI, or GSBus).
+ *
+ ******************************************************************************/
+
+acpi_status
+acpi_ex_read_serial_bus(union acpi_operand_object *obj_desc,
+			union acpi_operand_object **return_buffer)
+{
+	acpi_status status;
+	u32 buffer_length;
+	union acpi_operand_object *buffer_desc;
+	u32 function;
+	u16 accessor_type;
+
+	ACPI_FUNCTION_TRACE_PTR(ex_read_serial_bus, obj_desc);
+
+	/*
+	 * This is an SMBus, GSBus or IPMI read. We must create a buffer to
+	 * hold the data and then directly access the region handler.
+	 *
+	 * Note: SMBus and GSBus protocol value is passed in upper 16-bits
+	 * of Function
+	 *
+	 * Common buffer format:
+	 *     Status;    (Byte 0 of the data buffer)
+	 *     Length;    (Byte 1 of the data buffer)
+	 *     Data[x-1]: (Bytes 2-x of the arbitrary length data buffer)
+	 */
+	switch (obj_desc->field.region_obj->region.space_id) {
+	case ACPI_ADR_SPACE_SMBUS:
+
+		buffer_length = ACPI_SMBUS_BUFFER_SIZE;
+		function = ACPI_READ | (obj_desc->field.attribute << 16);
+		break;
+
+	case ACPI_ADR_SPACE_IPMI:
+
+		buffer_length = ACPI_IPMI_BUFFER_SIZE;
+		function = ACPI_READ;
+		break;
+
+	case ACPI_ADR_SPACE_GSBUS:
+
+		accessor_type = obj_desc->field.attribute;
+		if (accessor_type == AML_FIELD_ATTRIB_RAW_PROCESS_BYTES) {
+			ACPI_ERROR((AE_INFO,
+				    "Invalid direct read using bidirectional write-then-read protocol"));
+
+			return_ACPI_STATUS(AE_AML_PROTOCOL);
+		}
+
+		status =
+		    acpi_ex_get_protocol_buffer_length(accessor_type,
+						       &buffer_length);
+		if (ACPI_FAILURE(status)) {
+			ACPI_ERROR((AE_INFO,
+				    "Invalid protocol ID for GSBus: 0x%4.4X",
+				    accessor_type));
+
+			return_ACPI_STATUS(status);
+		}
+
+		/* Add header length to get the full size of the buffer */
+
+		buffer_length += ACPI_SERIAL_HEADER_SIZE;
+		function = ACPI_READ | (accessor_type << 16);
+		break;
+
+	default:
+		return_ACPI_STATUS(AE_AML_INVALID_SPACE_ID);
+	}
+
+	/* Create the local transfer buffer that is returned to the caller */
+
+	buffer_desc = acpi_ut_create_buffer_object(buffer_length);
+	if (!buffer_desc) {
+		return_ACPI_STATUS(AE_NO_MEMORY);
+	}
+
+	/* Lock entire transaction if requested */
+
+	acpi_ex_acquire_global_lock(obj_desc->common_field.field_flags);
+
+	/* Call the region handler for the write-then-read */
+
+	status = acpi_ex_access_region(obj_desc, 0,
+				       ACPI_CAST_PTR(u64,
+						     buffer_desc->buffer.
+						     pointer), function);
+	acpi_ex_release_global_lock(obj_desc->common_field.field_flags);
+
+	*return_buffer = buffer_desc;
+	return_ACPI_STATUS(status);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ex_write_serial_bus
+ *
+ * PARAMETERS:  source_desc         - Contains data to write
+ *              obj_desc            - The named field
+ *              return_buffer       - Where the return value is returned, if any
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Write to a named field that references a serial bus
+ *              (SMBus, IPMI, GSBus).
+ *
+ ******************************************************************************/
+
+acpi_status
+acpi_ex_write_serial_bus(union acpi_operand_object *source_desc,
+			 union acpi_operand_object *obj_desc,
+			 union acpi_operand_object **return_buffer)
+{
+	acpi_status status;
+	u32 buffer_length;
+	u32 data_length;
+	void *buffer;
+	union acpi_operand_object *buffer_desc;
+	u32 function;
+	u16 accessor_type;
+
+	ACPI_FUNCTION_TRACE_PTR(ex_write_serial_bus, obj_desc);
+
+	/*
+	 * This is an SMBus, GSBus or IPMI write. We will bypass the entire
+	 * field mechanism and handoff the buffer directly to the handler.
+	 * For these address spaces, the buffer is bidirectional; on a
+	 * write, return data is returned in the same buffer.
+	 *
+	 * Source must be a buffer of sufficient size, these are fixed size:
+	 * ACPI_SMBUS_BUFFER_SIZE, or ACPI_IPMI_BUFFER_SIZE.
+	 *
+	 * Note: SMBus and GSBus protocol type is passed in upper 16-bits
+	 * of Function
+	 *
+	 * Common buffer format:
+	 *     Status;    (Byte 0 of the data buffer)
+	 *     Length;    (Byte 1 of the data buffer)
+	 *     Data[x-1]: (Bytes 2-x of the arbitrary length data buffer)
+	 */
+	if (source_desc->common.type != ACPI_TYPE_BUFFER) {
+		ACPI_ERROR((AE_INFO,
+			    "SMBus/IPMI/GenericSerialBus write requires "
+			    "Buffer, found type %s",
+			    acpi_ut_get_object_type_name(source_desc)));
+
+		return_ACPI_STATUS(AE_AML_OPERAND_TYPE);
+	}
+
+	switch (obj_desc->field.region_obj->region.space_id) {
+	case ACPI_ADR_SPACE_SMBUS:
+
+		buffer_length = ACPI_SMBUS_BUFFER_SIZE;
+		data_length = ACPI_SMBUS_DATA_SIZE;
+		function = ACPI_WRITE | (obj_desc->field.attribute << 16);
+		break;
+
+	case ACPI_ADR_SPACE_IPMI:
+
+		buffer_length = ACPI_IPMI_BUFFER_SIZE;
+		data_length = ACPI_IPMI_DATA_SIZE;
+		function = ACPI_WRITE;
+		break;
+
+	case ACPI_ADR_SPACE_GSBUS:
+
+		accessor_type = obj_desc->field.attribute;
+		status =
+		    acpi_ex_get_protocol_buffer_length(accessor_type,
+						       &buffer_length);
+		if (ACPI_FAILURE(status)) {
+			ACPI_ERROR((AE_INFO,
+				    "Invalid protocol ID for GSBus: 0x%4.4X",
+				    accessor_type));
+
+			return_ACPI_STATUS(status);
+		}
+
+		/* Add header length to get the full size of the buffer */
+
+		buffer_length += ACPI_SERIAL_HEADER_SIZE;
+		data_length = source_desc->buffer.pointer[1];
+		function = ACPI_WRITE | (accessor_type << 16);
+		break;
+
+	default:
+		return_ACPI_STATUS(AE_AML_INVALID_SPACE_ID);
+	}
+
+#if 0
+	OBSOLETE ?
+	    /* Check for possible buffer overflow */
+	    if (data_length > source_desc->buffer.length) {
+		ACPI_ERROR((AE_INFO,
+			    "Length in buffer header (%u)(%u) is greater than "
+			    "the physical buffer length (%u) and will overflow",
+			    data_length, buffer_length,
+			    source_desc->buffer.length));
+
+		return_ACPI_STATUS(AE_AML_BUFFER_LIMIT);
+	}
+#endif
+
+	/* Create the transfer/bidirectional/return buffer */
+
+	buffer_desc = acpi_ut_create_buffer_object(buffer_length);
+	if (!buffer_desc) {
+		return_ACPI_STATUS(AE_NO_MEMORY);
+	}
+
+	/* Copy the input buffer data to the transfer buffer */
+
+	buffer = buffer_desc->buffer.pointer;
+	memcpy(buffer, source_desc->buffer.pointer, data_length);
+
+	/* Lock entire transaction if requested */
+
+	acpi_ex_acquire_global_lock(obj_desc->common_field.field_flags);
+
+	/*
+	 * Perform the write (returns status and perhaps data in the
+	 * same buffer)
+	 */
+	status = acpi_ex_access_region(obj_desc, 0, (u64 *)buffer, function);
+	acpi_ex_release_global_lock(obj_desc->common_field.field_flags);
+
+	*return_buffer = buffer_desc;
+	return_ACPI_STATUS(status);
+}