Arm
®
CoreLink™ GIC-600AE Generic Interrupt Controller
Technical Reference Manual
Document ID: 101206_0003_04_en
Issue: 04
Operation
big cores can be in class 1 and little cores in class 0, allowing 1 of N SPIs to be partitioned
according to the amount of processing they require.
GICD_CTLR.E1NWF
The GICD_CTLR.E1NWF bit controls whether the GIC-600AE wakes a core if there are no
other possible targets for a 1 of N SPI.
The GIC tries to wake the minimum of cores possible and only wakes a core if there is no
other possible target awake that is able to accept the 1 of N interrupt. Therefore, the GIC
uses the GICR_CTLR.DPG and GICR_CLASSR.Class bits to determine if any core is awake
that can accept the interrupt. If a suitable core is not awake, the GIC then wakes a core.
We strongly recommend that if you use GICD_CTLR.E1NWF, you must also set the
GICR_CTLR.DPGx bits to specify whether a core is likely to accept a particular interrupt
group in a timely manner. The GIC does not continue to wake cores until one is found. The
GIC-600AE uses two passes to try to find the best place for a 1 of N interrupt, by using a
round-robin arbiter between:
•
Any core that has its cpu_active signal set, is fully enabled for the interrupt, and has no
other pending interrupts.
•
Any core that is fully enabled for the interrupt and has no interrupts of a higher priority
than the 1 of N interrupt.
If neither option is available to the 1 of N, the interrupt is assigned to any legal target and
regularly re-evaluated to ensure that it is not excluded from other SPIs of the same priority.
4.6 Power management
The GIC-600AE can be powered down by the system power controller. The GIC also supports
the power controller powering down the cores that the GIC services. The GICR_WAKER and
the GICR_PWRR registers provide bits to control functions that are associated with power
management.
4.6.1 Redistributor power management
At reset, the Redistributors are considered to be powered down. To power up the Redistributors,
software must use the GICR_PWRR register.
This requirement is true for all GIC-600AE configurations.
The GICR_PWRR register can control Redistributor power management either by operating
through the core, or through the Redistributor.
Copyright © 2018–2020, 2022 Arm Limited (or its affiliates). All rights reserved.
Non-Confidential
Page 56 of 268
To Next Page
Loading...
Need help?
General
