GICD_IGROUPR<n>, Interrupt Group Registers, n = 0 - 31

The GICD_IGROUPR<n> characteristics are:

Purpose

Controls whether the corresponding interrupt is in Group 0 or Group 1.

Configuration

These registers are available in all GIC configurations. If GICD_CTLR.DS==0, these registers are Secure.

The number of implemented GICD_IGROUPR<n> registers is (GICD_TYPER.ITLinesNumber+1). Registers are numbered from 0.

GICD_IGROUPR0 is Banked for each connected PE with GICR_TYPER.Processor_Number < 8.

Accessing GICD_IGROUPR0 from a PE with GICR_TYPER.Processor_Number > 7 is CONSTRAINED UNPREDICTABLE:

Register is RAZ/WI.
An UNKNOWN banked copy of the register is accessed.

Attributes

GICD_IGROUPR<n> is a 32-bit register.

Field descriptions

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
Group_status_bit31	Group_status_bit30	Group_status_bit29	Group_status_bit28	Group_status_bit27	Group_status_bit26	Group_status_bit25	Group_status_bit24	Group_status_bit23	Group_status_bit22	Group_status_bit21	Group_status_bit20	Group_status_bit19	Group_status_bit18	Group_status_bit17	Group_status_bit16	Group_status_bit15	Group_status_bit14	Group_status_bit13	Group_status_bit12	Group_status_bit11	Group_status_bit10	Group_status_bit9	Group_status_bit8	Group_status_bit7	Group_status_bit6	Group_status_bit5	Group_status_bit4	Group_status_bit3	Group_status_bit2	Group_status_bit1	Group_status_bit0

Group_status_bit<x>, bit [x], for x = 31 to 0

Group status bit.

Group_status_bit<x>	Meaning
0b0	When GICD_CTLR.DS==1, the corresponding interrupt is Group 0. When GICD_CTLR.DS==0, the corresponding interrupt is Secure.
0b1	When GICD_CTLR.DS==1, the corresponding interrupt is Group 1. When GICD_CTLR.DS==0, the corresponding interrupt is Non-secure Group 1.

Group_status_bit<x>

Meaning

0b0

When GICD_CTLR.DS==1, the corresponding interrupt is Group 0.

When GICD_CTLR.DS==0, the corresponding interrupt is Secure.

0b1

When GICD_CTLR.DS==1, the corresponding interrupt is Group 1.

When GICD_CTLR.DS==0, the corresponding interrupt is Non-secure Group 1.

If affinity routing is enabled for the Security state of an interrupt, the bit that corresponds to the interrupt is concatenated with the equivalent bit in GICD_IGRPMODR<n> to form a 2-bit field that defines an interrupt group. The encoding of this field is described in GICD_IGRPMODR<n>.

If affinity routing is disabled for the Security state of an interrupt, then:

The corresponding GICD_IGRPMODR<n> bit is RES0.
For Secure interrupts, the interrupt is Secure Group 0.
For Non-secure interrupts, the interrupt is Non-secure Group 1.

The reset behavior of this field is:

On a GIC reset:
- When n == 0, this field resets to an UNKNOWN value.
- When n > 0, this field resets to 0.

Additional information

For INTID m, when DIV and MOD are the integer division and modulo operations:

The corresponding GICD_IGROUP<n> number, n, is given by n = m DIV 32.
The offset of the required GICD_IGROUP is (0x080 + (4*n)).
The bit number of the required group modifier bit in this register is m MOD 32.

Accessing GICD_IGROUPR<n>

For SGIs and PPIs:

When ARE is 1 for the Security state of an interrupt, the field for that interrupt is RES0 and an implementation is permitted to make the field RAZ/WI in this case.
Equivalent functionality is provided by GICR_IGROUPR0.

When GICD_CTLR.DS==0, the register is RAZ/WI to Non-secure accesses.

Bits corresponding to unimplemented interrupts are RAZ/WI.

Note

Accesses to GICD_IGROUPR0 when affinity routing is not enabled for a Security state access the same state as GICR_IGROUPR0, and must update Redistributor state associated with the PE performing the accesses. Implementations must ensure that an interrupt that is pending at the time of the write uses either the old value or the new value and must ensure that the interrupt is neither lost nor handled more than one time. The effect of the change must be visible in finite time.

GICD_IGROUPR<n> can be accessed through the memory-mapped interfaces:

Component	Frame	Offset	Instance
GIC Distributor	Dist_base	0x0080 + (4 * n)	GICD_IGROUPR<n>

Accesses on this interface are RW.

26/03/2024 09:49; 67c0ae5282a7629ba0ea0ba7267b43cd4f7939f6