Functional Description
5.2.4
Hot-Plug
Each root port implements a Hot-Plug controller which performs the following:
• Messages to turn on / off / blink LEDs
• Presence and attention button detection
• Interrupt generation
The root port only allows Hot-Plug with modules (e.g., ExpressCard*). Edge-connector
based Hot-Plug is not supported.
5.2.4.1
Presence Detection
When a module is plugged in and power is supplied, the physical layer will detect the
presence of the device, and the root port sets SLSTS.PDS (D28:F0/F1/F2/F3/F4/
F5:Offset 5Ah:bit 6) and SLSTS.PDC (D28:F0/F1/F2/F3:Offset 6h:bit 3). If SLCTL.PDE
(D28:F0/F1/F2/F3F4/F5:Offset 58h:bit 3) and SLCTL.HPE (D28:F0/F1/F2/F3F4/
F5:Offset 58h:bit 5) are both set, the root port will also generate an interrupt.
When a module is removed (via the physical layer detection), the root port clears
SLSTS.PDS and sets SLSTS.PDC. If SLCTL.PDE and SLCTL.HPE are both set, the root
port will also generate an interrupt.
5.2.4.2
Message Generation
When system software writes to SLCTL.AIC (D28:F0/F1/F2/F3F4/F5:Offset 58h:bits
7:6) or SLCTL.PIC (D28:F0/F1/F2/F3F4/F5:Offset 58h:bits 9:8), the root port will send
a message down the link to change the state of LEDs on the module.
Writes to these fields are non-postable cycles, and the resulting message is a postable
cycle. When receiving one of these writes, the root port performs the following:
• Changes the state in the register.
• Generates a completion into the upstream queue
• Formulates a message for the downstream port if the field is written to regardless
of if the field changed.
• Generates the message on the downstream port
• When the last message of a command is transmitted, sets SLSTS.CCE (D28:F0/F1/
F2/F3F4/F5:Offset 58h:bit 4) to indicate the command has completed. If
SLCTL.CCE and SLCTL.HPE (D28:F0/F1/F2/F3F4/F5:Offset 58h:bit 5) are set, the
root port generates an interrupt.
The command completed register (SLSTS.CC) applies only to commands issued by
software to control the Attention Indicator (SLCTL.AIC), Power Indicator (SLCTL.PIC),
or Power Controller (SLCTL.PCC). However, writes to other parts of the Slot Control
Register would invariably end up writing to the indicators, power controller fields;
Hence, any write to the Slot Control Register is considered a command and if enabled,
will result in a command complete interrupt. The only exception to this rule is a write to
disable the command complete interrupt which will not result in a command complete
interrupt.
A single write to the Slot Control register is considered to be a single command, and
hence receives a single command complete, even if the write affects more than one
field in the Slot Control Register.
100
Datasheet
INTEL [ INTEL ]
