Datasheet

Functional Description
126 Intel® Xeon® Processor D-1500 Product Family
Datasheet - Volume 1 of 4: Integrated Platform Controller Hub
March 2015
for the associated port. See Section 7.3.1 of the AHCI Specification for more
information.
3.15.11 SGPIO Signals
The SGPIO signals, in accordance to the SFF-8485 specification, support per-port LED
signaling. These signals are not related to SATALED#, which allows for simplified
indication of SATA command activity. The SGPIO group interfaces with an external
controller chip that fetches and serializes the data for driving across the SGPIO bus.
The output signals then control the LEDs. This feature is only valid in AHCI/RAID mode.
Note: Intel does not validate all possible usage cases of this feature. Customers should
validate their specific design implementation on their own platforms.
3.15.11.1 Mechanism
The enclosure management for SATA Controller 1 (Device 31: Function 2) involves
sending messages that control LEDs in the enclosure. The messages for this function
are stored after the normal registers in the AHCI BAR, at Offset 580h bytes for Intel®
Xeon® Processor D-1500 Product Family from the beginning of the AHCI BAR as
specified by the EM_LOC global register (Section 8.4.1.6).
Software creates messages for transmission in the enclosure management message
buffer. The data in the message buffer should not be changed if CTL.TM bit is set by
software to transmit an update message. Software should only update the message
buffer when CTL.TM bit is cleared by hardware otherwise the message transmitted will
be indeterminate. Software then writes a register to cause hardware to transmit the
message or take appropriate action based on the message content. The software
should only create message types supported by the controller, which is LED messages
for Intel® Xeon® Processor D-1500 Product Family. If the software creates other non
LED message types (such as, SAF-TE, SES-2), the SGPIO interface may hang and the
result is indeterminate.
During reset all SGPIO pins will be in tri-state state. The interface will continue staying
in tri-state state after reset until the first transmission occurs, when software programs
the message buffer and sets the transmit bit CTL.TM. The SATA host controller will
initiate the transmission by driving SCLOCK and at the same time driving the SLOAD to
“0‟ prior to the actual bit stream transmission. The Host will drive SLOAD low for at
least 5 SCLOCK then only start the bit stream by driving the SLOAD to high. SLOAD will
be driven high for 1 SCLOCK, followed by vendor-specific pattern that is default to
“0000” if software is yet to program the value. A total of 18-bit streams from 6 ports
(Port0, Port1, Port2, Port3, Port4 and Port5) of 3-bit per port LED message will be
transmitted on SDATAOUT0 pin after the SLOAD is driven high for 1 SCLOCK. Only 2
ports (port4, and port 5) of 6-bit total LED message follow by 12 bits of tri-state value
will be transmitted out on SDATAOUT1 pin.
All the default LED message values will be high prior to software setting them, except
the Activity LED message that is configured to be hardware driven that will be
generated based on the activity from the respective port. All the LED message values
will be driven to ‘1’ for the port that is unimplemented as indicated in the Port
Implemented register regardless of the software programmed value through the
message buffer.