Advanced Configuration and Power Interface Specification

Advanced Configuration and Power Interface Specification
by this protocol and thus only a single element (at offset 0) can be specified in the field definition.
This protocol transfers no data.
The following ASL code illustrates how a device supporting the Read/Write Quick protocol should
be accessed:
OperationRegion(SMBD, SMBus, 0x4200, 0x100) // SMBus device at slave address 0x42
Field(SMBD, BufferAcc, NoLock, Preserve)
{
AccessAs(BufferAcc, SMBQuick)
// Use the SMBus Read/Write Quick protocol
FLD0, 8 // Virtual register at command value 0.
}
/* Create the SMBus data buffer */
Name(BUFF, Buffer(34){})
CreateByteField(BUFF, 0x00, OB1)
/* Signal device (e.g. OFF) */
Store(FLD0, BUFF)
If(LEqual(OB1, 0x00)) {…}
/* Signal device (e.g. ON) */
Store(BUFF, FLD0)
// Create SMBus data buffer as BUFF
// OB1 = Status (Byte)
// Invoke Read Quick transaction
// Successful?
// Invoke Write Quick transaction
In this example, a single field element (FLD0) at offset 0 is defined to represent the protocol’s read/
write bit. Access to FLD0 will cause an SMBus transaction to occur to the device. Reading the field
results in a Read Quick, and writing to the field results in a Write Quick. In either case data is not
transferred—access to the register is simply used as a mechanism to invoke the transaction.
13.3.2 Send/Receive Byte (SMBSendReceive)
The SMBus Send/Receive Byte protocol (SMBSendReceive) transfers a single byte of data. Like
Read/Write Quick, command values are not used by this protocol and thus only a single element (at
offset 0) can be specified in the field definition.
The following ASL code illustrates how a device supporting the Send/Receive Byte protocol should
be accessed:
OperationRegion(SMBD, SMBus, 0x4200, 0x100) // SMBus device at slave address 0x42
Field(SMBD, BufferAcc, NoLock, Preserve)
{
}
AccessAs(BufferAcc, SMBSendReceive) // Use the SMBus Send/Receive Byte protocol
FLD0, 8 // Virtual register at command value 0.
// Create the SMBus data buffer
Name(BUFF, Buffer(34){})
CreateByteField(BUFF, 0x00, STAT)
CreateByteField(BUFF, 0x02, DATA)
// Create SMBus data buffer as BUFF
// STAT = Status (Byte)
// DATA = Data (Byte)
670 April, 2015 Version 6.0