Advanced Configuration and Power Interface Specification

ACPI Software Programming Model
The following ASL code illustrates how a device supporting the Read/Write N Bytes protocol
should be accessed:
OperationRegion(TOP1, GenericSerialBus, 0x00, 0x100)
Field(TOP1, BufferAcc, NoLock, Preserve)
{
Connection(I2CSerialBus(0x5a,,100000,,"\_SB.I2C",,,,RawDataBuffer(){1,6}))
Offset(0x0),
AccessAs(BufferAcc, AttribBytes (4)),
TFK1, 8, //TFK1 at command value 0
TFK2, 8, //TFK2 at command value 1
Connection(I2CSerialBus(0x5b,,100000,,"\_SB.I2C",,,,RawDataBuffer(){2,9}))
// same connection attribute, but different vendor data passed to driver
AccessAs(BufferAcc, AttribByte)
TM1, 8 //TM1 at command value 2
}
// Create the GenericSerialBus data buffer
Name(BUFF, Buffer(34){})
// Create SerialBus buf as BUFF
CreateByteField(BUFF, 0x00, STAT) // STAT = Status (Byte)
CreateBytefield(BUFF, 0x01, LEN) // LEN = Length (Byte)
CreateWordField(BUFF, 0x02, DATW) // DATW = Data (Word - Bytes 2 & 3, or 16 bits)
CreateField(BUFF, 16, 256, DBUF) // DBUF = Data (Bytes 2-34)
CreateField(BUFF, 16, 32, DATD) // DATD = Data (DWord)
// Read block of data from the device using command value 0
Store(TFK1, BUFF)
If(LNotEqual(STAT, 0x00)) {
Return(0)
}
// Write block of data to the device using command value 1
Store(Store(BUFF,TFK2), BUFF)
If(LNotEqual(STAT, 0x00)) {
Return(0)
}
In this example, two field elements (TFK1, and TFK2) are defined to represent the virtual registers
for command values 0 and 1. Access to any of the field elements will cause a GenericSerialBus
transaction to occur to the device of the length specified in the AccessAttributes.
5.5.2.4.5.3.9 Raw Read/Write N Bytes (AttribRawBytes)
The GenericSerialBus Raw Read/Write N Bytes protocol (AttribRawBytes) transfers variable-sized
data. The actual number of bytes to read or write is specified as part of the AccessAs attribute. The
initial command value specified in the operation region definition is ignored by Raw accesses.
The following ASL code illustrates how a device supporting the Read/Write N Bytes protocol
should be accessed:
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