exprep.c

LINUX 2.6.17.4的源码

		/*
		 * buffer_field access can be on any byte boundary, so the
		 * byte_alignment is always 1 byte -- regardless of any byte_alignment
		 * implied by the field access type.
		 */
		byte_alignment = 1;
	}

	*return_byte_alignment = byte_alignment;
	return_UINT32(bit_length);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_prep_common_field_object
 *
 * PARAMETERS:  obj_desc            - The field object
 *              field_flags         - Access, lock_rule, and update_rule.
 *                                    The format of a field_flag is described
 *                                    in the ACPI specification
 *              field_attribute     - Special attributes (not used)
 *              field_bit_position  - Field start position
 *              field_bit_length    - Field length in number of bits
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Initialize the areas of the field object that are common
 *              to the various types of fields.  Note: This is very "sensitive"
 *              code because we are solving the general case for field
 *              alignment.
 *
 ******************************************************************************/

acpi_status
acpi_ex_prep_common_field_object(union acpi_operand_object *obj_desc,
				 u8 field_flags,
				 u8 field_attribute,
				 u32 field_bit_position, u32 field_bit_length)
{
	u32 access_bit_width;
	u32 byte_alignment;
	u32 nearest_byte_address;

	ACPI_FUNCTION_TRACE("ex_prep_common_field_object");

	/*
	 * Note: the structure being initialized is the
	 * ACPI_COMMON_FIELD_INFO;  No structure fields outside of the common
	 * area are initialized by this procedure.
	 */
	obj_desc->common_field.field_flags = field_flags;
	obj_desc->common_field.attribute = field_attribute;
	obj_desc->common_field.bit_length = field_bit_length;

	/*
	 * Decode the access type so we can compute offsets.  The access type gives
	 * two pieces of information - the width of each field access and the
	 * necessary byte_alignment (address granularity) of the access.
	 *
	 * For any_acc, the access_bit_width is the largest width that is both
	 * necessary and possible in an attempt to access the whole field in one
	 * I/O operation.  However, for any_acc, the byte_alignment is always one
	 * byte.
	 *
	 * For all Buffer Fields, the byte_alignment is always one byte.
	 *
	 * For all other access types (Byte, Word, Dword, Qword), the Bitwidth is
	 * the same (equivalent) as the byte_alignment.
	 */
	access_bit_width = acpi_ex_decode_field_access(obj_desc, field_flags,
						       &byte_alignment);
	if (!access_bit_width) {
		return_ACPI_STATUS(AE_AML_OPERAND_VALUE);
	}

	/* Setup width (access granularity) fields */

	obj_desc->common_field.access_byte_width = (u8)
	    ACPI_DIV_8(access_bit_width);	/* 1,  2,  4,  8 */

	obj_desc->common_field.access_bit_width = (u8) access_bit_width;

	/*
	 * base_byte_offset is the address of the start of the field within the
	 * region.  It is the byte address of the first *datum* (field-width data
	 * unit) of the field. (i.e., the first datum that contains at least the
	 * first *bit* of the field.)
	 *
	 * Note: byte_alignment is always either equal to the access_bit_width or 8
	 * (Byte access), and it defines the addressing granularity of the parent
	 * region or buffer.
	 */
	nearest_byte_address =
	    ACPI_ROUND_BITS_DOWN_TO_BYTES(field_bit_position);
	obj_desc->common_field.base_byte_offset = (u32)
	    ACPI_ROUND_DOWN(nearest_byte_address, byte_alignment);

	/*
	 * start_field_bit_offset is the offset of the first bit of the field within
	 * a field datum.
	 */
	obj_desc->common_field.start_field_bit_offset = (u8)
	    (field_bit_position -
	     ACPI_MUL_8(obj_desc->common_field.base_byte_offset));

	/*
	 * Does the entire field fit within a single field access element? (datum)
	 * (i.e., without crossing a datum boundary)
	 */
	if ((obj_desc->common_field.start_field_bit_offset +
	     field_bit_length) <= (u16) access_bit_width) {
		obj_desc->common.flags |= AOPOBJ_SINGLE_DATUM;
	}

	return_ACPI_STATUS(AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_prep_field_value
 *
 * PARAMETERS:  Info    - Contains all field creation info
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Construct an union acpi_operand_object of type def_field and
 *              connect it to the parent Node.
 *
 ******************************************************************************/

acpi_status acpi_ex_prep_field_value(struct acpi_create_field_info *info)
{
	union acpi_operand_object *obj_desc;
	u32 type;
	acpi_status status;

	ACPI_FUNCTION_TRACE("ex_prep_field_value");

	/* Parameter validation */

	if (info->field_type != ACPI_TYPE_LOCAL_INDEX_FIELD) {
		if (!info->region_node) {
			ACPI_ERROR((AE_INFO, "Null region_node"));
			return_ACPI_STATUS(AE_AML_NO_OPERAND);
		}

		type = acpi_ns_get_type(info->region_node);
		if (type != ACPI_TYPE_REGION) {
			ACPI_ERROR((AE_INFO,
				    "Needed Region, found type %X (%s)",
				    type, acpi_ut_get_type_name(type)));

			return_ACPI_STATUS(AE_AML_OPERAND_TYPE);
		}
	}

	/* Allocate a new field object */

	obj_desc = acpi_ut_create_internal_object(info->field_type);
	if (!obj_desc) {
		return_ACPI_STATUS(AE_NO_MEMORY);
	}

	/* Initialize areas of the object that are common to all fields */

	obj_desc->common_field.node = info->field_node;
	status = acpi_ex_prep_common_field_object(obj_desc, info->field_flags,
						  info->attribute,
						  info->field_bit_position,
						  info->field_bit_length);
	if (ACPI_FAILURE(status)) {
		acpi_ut_delete_object_desc(obj_desc);
		return_ACPI_STATUS(status);
	}

	/* Initialize areas of the object that are specific to the field type */

	switch (info->field_type) {
	case ACPI_TYPE_LOCAL_REGION_FIELD:

		obj_desc->field.region_obj =
		    acpi_ns_get_attached_object(info->region_node);

		/* An additional reference for the container */

		acpi_ut_add_reference(obj_desc->field.region_obj);

		ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
				  "region_field: bit_off %X, Off %X, Gran %X, Region %p\n",
				  obj_desc->field.start_field_bit_offset,
				  obj_desc->field.base_byte_offset,
				  obj_desc->field.access_byte_width,
				  obj_desc->field.region_obj));
		break;

	case ACPI_TYPE_LOCAL_BANK_FIELD:

		obj_desc->bank_field.value = info->bank_value;
		obj_desc->bank_field.region_obj =
		    acpi_ns_get_attached_object(info->region_node);
		obj_desc->bank_field.bank_obj =
		    acpi_ns_get_attached_object(info->register_node);

		/* An additional reference for the attached objects */

		acpi_ut_add_reference(obj_desc->bank_field.region_obj);
		acpi_ut_add_reference(obj_desc->bank_field.bank_obj);

		ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
				  "Bank Field: bit_off %X, Off %X, Gran %X, Region %p, bank_reg %p\n",
				  obj_desc->bank_field.start_field_bit_offset,
				  obj_desc->bank_field.base_byte_offset,
				  obj_desc->field.access_byte_width,
				  obj_desc->bank_field.region_obj,
				  obj_desc->bank_field.bank_obj));
		break;

	case ACPI_TYPE_LOCAL_INDEX_FIELD:

		/* Get the Index and Data registers */

		obj_desc->index_field.index_obj =
		    acpi_ns_get_attached_object(info->register_node);
		obj_desc->index_field.data_obj =
		    acpi_ns_get_attached_object(info->data_register_node);

		if (!obj_desc->index_field.data_obj
		    || !obj_desc->index_field.index_obj) {
			ACPI_ERROR((AE_INFO,
				    "Null Index Object during field prep"));
			acpi_ut_delete_object_desc(obj_desc);
			return_ACPI_STATUS(AE_AML_INTERNAL);
		}

		/* An additional reference for the attached objects */

		acpi_ut_add_reference(obj_desc->index_field.data_obj);
		acpi_ut_add_reference(obj_desc->index_field.index_obj);

		/*
		 * The value written to the Index register is the byte offset of the
		 * target field
		 * Note: may change code to: ACPI_DIV_8 (Info->field_bit_position)
		 */
		obj_desc->index_field.value = (u32)
		    (info->field_bit_position /
		     ACPI_MUL_8(obj_desc->field.access_byte_width));

		ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
				  "index_field: bit_off %X, Off %X, Value %X, Gran %X, Index %p, Data %p\n",
				  obj_desc->index_field.start_field_bit_offset,
				  obj_desc->index_field.base_byte_offset,
				  obj_desc->index_field.value,
				  obj_desc->field.access_byte_width,
				  obj_desc->index_field.index_obj,
				  obj_desc->index_field.data_obj));
		break;

	default:
		/* No other types should get here */
		break;
	}

	/*
	 * Store the constructed descriptor (obj_desc) into the parent Node,
	 * preserving the current type of that named_obj.
	 */
	status = acpi_ns_attach_object(info->field_node, obj_desc,
				       acpi_ns_get_type(info->field_node));

	ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
			  "Set named_obj %p [%4.4s], obj_desc %p\n",
			  info->field_node,
			  acpi_ut_get_node_name(info->field_node), obj_desc));

	/* Remove local reference to the object */

	acpi_ut_remove_reference(obj_desc);
	return_ACPI_STATUS(status);
}