amfldio.c

Linux内核源代码 为压缩文件 是<<Linux内核>>一书中的源代码

	field_byte_width = DIV_8 (field_bit_width);
	status = acpi_aml_setup_field (obj_desc, rgn_desc, field_bit_width);
	if (ACPI_FAILURE (status)) {
		return (status);
	}


	/*
	 * Set offset to next multiple of field width,
	 *  add region base address and offset within the field
	 */
	address = rgn_desc->region.address +
			  (obj_desc->field.offset * field_byte_width) +
			  field_byte_offset;

	/* Invoke the appropriate Address_space/Op_region handler */

	status = acpi_ev_address_space_dispatch (rgn_desc, ADDRESS_SPACE_WRITE,
			 address, field_bit_width, &value);



	return (status);
}


/*****************************************************************************
 *
 * FUNCTION:    Acpi_aml_write_field_data_with_update_rule
 *
 * PARAMETERS:  *Obj_desc           - Field to be set
 *              Value               - Value to store
 *              Field_bit_width     - Field Width in bits (8, 16, or 32)
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Apply the field update rule to a field write
 *
 ****************************************************************************/

static ACPI_STATUS
acpi_aml_write_field_data_with_update_rule (
	ACPI_OPERAND_OBJECT     *obj_desc,
	u32                     mask,
	u32                     field_value,
	u32                     this_field_byte_offset,
	u32                     bit_granularity)
{
	ACPI_STATUS             status = AE_OK;
	u32                     merged_value;
	u32                     current_value;


	/* Start with the new bits  */

	merged_value = field_value;

	/* Check if update rule needs to be applied (not if mask is all ones) */


	/* Decode the update rule */

	switch (obj_desc->field.update_rule)
	{

	case UPDATE_PRESERVE:

		/*
		 * Read the current contents of the byte/word/dword containing
		 * the field, and merge with the new field value.
		 */
		status = acpi_aml_read_field_data (obj_desc, this_field_byte_offset,
				   bit_granularity, &current_value);
		merged_value |= (current_value & ~mask);
		break;


	case UPDATE_WRITE_AS_ONES:

		/* Set positions outside the field to all ones */

		merged_value |= ~mask;
		break;


	case UPDATE_WRITE_AS_ZEROS:

		/* Set positions outside the field to all zeros */

		merged_value &= mask;
		break;


	default:
		status = AE_AML_OPERAND_VALUE;
	}


	/* Write the merged value */

	if (ACPI_SUCCESS (status)) {
		status = acpi_aml_write_field_data (obj_desc, this_field_byte_offset,
				   bit_granularity, merged_value);
	}

	return (status);
}


/*****************************************************************************
 *
 * FUNCTION:    Acpi_aml_write_field
 *
 * PARAMETERS:  *Obj_desc           - Field to be set
 *              Value               - Value to store
 *              Field_bit_width     - Field Width in bits (8, 16, or 32)
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Store the value into the given field
 *
 ****************************************************************************/

ACPI_STATUS
acpi_aml_write_field (
	ACPI_OPERAND_OBJECT     *obj_desc,
	void                    *buffer,
	u32                     buffer_length,
	u32                     byte_length,
	u32                     datum_length,
	u32                     bit_granularity,
	u32                     byte_granularity)
{
	ACPI_STATUS             status;
	u32                     this_field_byte_offset;
	u32                     this_field_datum_offset;
	u32                     mask;
	u32                     merged_datum;
	u32                     previous_raw_datum;
	u32                     this_raw_datum;
	u32                     field_value;
	u32                     valid_field_bits;


	/*
	 * Break the request into up to three parts:
	 * non-aligned part at start, aligned part in middle, non-aligned part
	 * at end --- Just like an I/O request ---
	 */

	this_field_byte_offset = 0;
	this_field_datum_offset= 0;

	/* Get a datum */

	switch (byte_granularity)
	{
	case 1:
		previous_raw_datum = ((u8 *) buffer) [this_field_datum_offset];
		break;

	case 2:
		MOVE_UNALIGNED16_TO_32 (&previous_raw_datum, &(((u16 *) buffer) [this_field_datum_offset]));
		break;

	case 4:
		MOVE_UNALIGNED32_TO_32 (&previous_raw_datum, &(((u32 *) buffer) [this_field_datum_offset]));
		break;

	default:
		status = AE_AML_OPERAND_VALUE;
		goto cleanup;
	}


	/*
	 * Write a partial field datum if field does not begin on a datum boundary
	 *
	 * Construct Mask with 1 bits where the field is, 0 bits elsewhere
	 *
	 * 1) Bits above the field
	 */

	mask = (((u32)(-1)) << (u32)obj_desc->field.bit_offset);

	/* 2) Only the bottom 5 bits are valid for a shift operation. */

	if ((obj_desc->field.bit_offset + obj_desc->field_unit.length) < 32) {
		/* Bits above the field */

		mask &= (~(((u32)(-1)) << ((u32)obj_desc->field.bit_offset +
				   (u32)obj_desc->field_unit.length)));
	}

	/* 3) Shift and mask the value into the field position */

	field_value = (previous_raw_datum << obj_desc->field.bit_offset) & mask;

	status = acpi_aml_write_field_data_with_update_rule (obj_desc, mask, field_value,
			 this_field_byte_offset,
			 bit_granularity);
	if (ACPI_FAILURE (status)) {
		goto cleanup;
	}


	/* If the field fits within one datum, we are done. */

	if ((datum_length == 1) &&
	   ((obj_desc->field.bit_offset + obj_desc->field_unit.length) <=
			(u16) bit_granularity))
	{
		goto cleanup;
	}

	/*
	 * We don't need to worry about the update rule for these data, because
	 * all of the bits are part of the field.
	 *
	 * Can't write the last datum, however, because it might contain bits that
	 * are not part of the field -- the update rule must be applied.
	 */

	while (this_field_datum_offset < (datum_length - 1)) {
		this_field_datum_offset++;

		/* Get the next raw datum, it contains bits of the current field datum... */

		switch (byte_granularity)
		{
		case 1:
			this_raw_datum = ((u8 *) buffer) [this_field_datum_offset];
			break;

		case 2:
			MOVE_UNALIGNED16_TO_32 (&this_raw_datum, &(((u16 *) buffer) [this_field_datum_offset]));
			break;

		case 4:
			MOVE_UNALIGNED32_TO_32 (&this_raw_datum, &(((u32 *) buffer) [this_field_datum_offset]));
			break;

		default:
			status = AE_AML_OPERAND_VALUE;
			goto cleanup;
		}

		/*
		 * Put together bits of the two raw data to make a complete field
		 * datum
		 */

		if (obj_desc->field.bit_offset != 0) {
			merged_datum =
				(previous_raw_datum >> (bit_granularity - obj_desc->field.bit_offset)) |
				(this_raw_datum << obj_desc->field.bit_offset);
		}

		else {
			merged_datum = this_raw_datum;
		}

		/* Now write the completed datum  */


		status = acpi_aml_write_field_data (obj_desc,
				   this_field_byte_offset + byte_granularity,
				   bit_granularity, merged_datum);
		if (ACPI_FAILURE (status)) {
			goto cleanup;
		}


		/*
		 * Save the most recent datum since it contains bits of
		 * the *next* field datum
		 */

		previous_raw_datum = this_raw_datum;

		this_field_byte_offset += byte_granularity;

	}  /* while */


	/* Write a partial field datum if field does not end on a datum boundary */

	if ((obj_desc->field_unit.length + obj_desc->field_unit.bit_offset) %
		bit_granularity)
	{
		switch (byte_granularity)
		{
		case 1:
			this_raw_datum = ((u8 *) buffer) [this_field_datum_offset];
			break;

		case 2:
			MOVE_UNALIGNED16_TO_32 (&this_raw_datum, &(((u16 *) buffer) [this_field_datum_offset]));
			break;

		case 4:
			MOVE_UNALIGNED32_TO_32 (&this_raw_datum, &(((u32 *) buffer) [this_field_datum_offset]));
			break;
		}

		/* Construct Mask with 1 bits where the field is, 0 bits elsewhere */

		valid_field_bits = ((obj_desc->field_unit.length % bit_granularity) +
				   obj_desc->field.bit_offset);

		mask = (((u32) 1 << valid_field_bits) - (u32) 1);

		/* Shift and mask the value into the field position */

		field_value = (previous_raw_datum >>
				  (bit_granularity - obj_desc->field.bit_offset)) & mask;

		status = acpi_aml_write_field_data_with_update_rule (obj_desc, mask, field_value,
				 this_field_byte_offset + byte_granularity,
				 bit_granularity);
		if (ACPI_FAILURE (status)) {
			goto cleanup;
		}
	}


cleanup:

	return (status);
}