2.2.2 Redistributor GIC Stream protocol interface

The GIC-600 uses the GIC Stream protocol interface to send interrupts to the core and receive notifications when the core activates interrupts. The GIC Stream protocol interface has a pair of 16-bit wide AXI4-Stream interfaces, one upstream interface, and one downstream interface.

The GIC Stream protocol interface, also referred to as the GIC Stream interface, uses the GIC Stream protocol to pass interrupts and responses to the CPU interface inside each core.

Table 2-7 GIC Stream protocol interface signals

Signal name Description
iri Prefix which identifies the names of the downstream interface signals. These signals are sent by the GIC Stream master. On this interface, the Redistributor is the master and the CPU interface is the slave.
icc Prefix which identifies the names of the upstream interface signals. These signals are sent by the GIC Stream slave. On this interface, the CPU interface is the master and the Redistributor is the slave.
iritdest The GIC Stream master interface uses this signal to direct packets to one core within the cluster.
icctid The GIC Stream slave interface uses this signal to determine which core within the cluster sent a packet.

Both the iritdest and icctid can support 64 cores that use packed binary encoding, as opposed to one-hot encoding. They can also be divided down using an AXI4-Stream crossbar to support clusters of an arbitrary number of cores from 1-64.

The necessary crossbar is generated as part of the render process based on the number of GIC-Stream buses that are specified for each Redistributor.

Non-ConfidentialPDF file icon PDF version100336_0104_00_en
Copyright © 2016–2018 Arm Limited or its affiliates. All rights reserved.