Advanced Configuration and Power Interface Specification

Advanced Configuration and Power Interface Specification
Table 12-292 Events for Which Embedded Controller Must Generate SCIs
Event
IBF=0
OBF=1
SCI_EVT=1
Description
Signals that the embedded controller has read the last command or data from the input
buffer and the host is free to send more data.
Signals that the embedded controller has written a byte of data into the output buffer and
the host is free to read the returned data.
Signals that the embedded controller has detected an event that requires OS attention.
OSPM should issue a query (QR_EC) command to find the cause of the event.
12.6.2 Command Interrupt Model
The embedded controller must generate SCIs for commands as follows:
Table 12-293 Read Command (3 Bytes)
Byte #1 (Command byte Header) Interrupt on IBF=0
Byte #2 (Address byte to read) No Interrupt
Byte #3 (Data read to host) Interrupt on OBF=1
Table 12-294 Write Command (3 Bytes)
Byte #1 (Command byte Header) Interrupt on IBF=0
Byte #2 (Address byte to write) Interrupt on IBF=0
Byte #3 (Data to read ) Interrupt on IBF=0
Table 12-295 Query Command (2 Bytes
Byte #1 (Command byte Header) No Interrupt
Byte #2 (Query value to host) Interrupt on OBF=1
Table 12-296 Burst Enable Command (2 Bytes)
Byte #1 (Command byte Header) No Interrupt
Byte #2 (Burst acknowledge byte) Interrupt on OBF=1
Table 12-297 Burst Disable Command (1 Byte)
Byte #1 (Command byte Header) Interrupt on IBF=0
12.7 Embedded Controller Interfacing Algorithms
To initiate communications with the embedded controller, OSPM or system management handler
acquires ownership of the interface. This ownership is acquired through the use of the Global Lock
(described in Section 5.2.10.1, “Global Lock”), or is owned by default by OSPM as a non-shared
resource (and the Global Lock is not required for accessibility).
644 April, 2015 Version 6.0