Arm
®
CoreLink™ GIC-600AE Generic Interrupt Controller
Technical Reference Manual
Document ID: 101206_0003_04_en
Issue: 04
Operation
4.16.3 SPI ownership for multichip operation
The owner of an SPI block is defined by the GICD_CHIPR<n> registers.
You can remove SPI blocks from a chip and add them to another chip by reprogramming the
relevant GICD_CHIPR<n> registers during operation. As with all Routing table operations,
GICD_DCHIPR.PUP must be polled to check completion of the operation.
Before you change the owner of an SPI block, you must ensure that the GICD_CTLR group enables
have cleared, GICD_CTLR.RWP has returned to 0, and that the SPI blocks are removed from a chip
before they are added to another chip.
When an SPI block is removed from, or added to, a chip, all programming that is associated with
the SPI block returns to the reset state.
You must not alter the SPI_BLOCK_MIN of an online chip because the results are unpredictable. To
change SPI_BLOCK_MIN:
1.
Move the chip offline by setting GICD_CHIPR<n>.SocketState = 0.
2.
Alter SPI_BLOCK_MIN when the chip is brought back online.
4.16.4 Power control and P-Channel
You can use the P-Channel to isolate a chip from the system.
The P-Channel has the following states:
RUN (pstate signal == 0x0)
The normal functional mode
CONFIG (pstate signal == 0x9)
The GIC does not send any cross-chip messages. It accepts incoming messages but does not
process them.
OFF (pstate signal == 0xF)
The GIC does not send any cross-chip messages and does not accept any incoming
messages. The icrdtready signal is clamped LOW to prevent accesses entering the GIC.
While in both the CONFIG and OFF states, register accesses that are normally sent to another chip
are serviced locally. Therefore, the Routing table registers read the local versions instead of the
copies of the Routing table owner. The same is true for SPIs that are owned remotely. Therefore, it
is safe to save and restore the Distributor register values in either of these P-Channel states.
The GIC can exit reset in either the RUN or OFF states by setting the initial value of the pstate
signal. If you have saved register values and intend to restore them, you must use the OFF state
and restore the Routing table first, before attempting to restore any SPI registers.
Copyright © 2018–2020, 2022 Arm Limited (or its affiliates). All rights reserved.
Non-Confidential
Page 91 of 268
To Next Page
Loading...
Need help?
General
