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ICH_ELRSR, Interrupt Controller Empty List Register Status Register

The ICH_ELRSR characteristics are:

Purpose

Indicates which List registers contain valid interrupts.

Configuration

AArch32 System register ICH_ELRSR bits [31:0] are architecturally mapped to AArch64 System register ICH_ELRSR_EL2[31:0] .

If EL2 is not implemented, this register is RES0 from EL3.

Attributes

ICH_ELRSR is a 32-bit register.

Field descriptions

The ICH_ELRSR bit assignments are:

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
0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	Status<n>, bit [n], for n = 0 to 15

Bits [31:16]

Reserved, RES0.

Status<n>, bit [n], for n = 0 to 15

Status bit for List register <n>, ICH_LR<n>:

Status<n>	Meaning
0b0	List register ICH_LR<n>, if implemented, contains a valid interrupt. Using this List register can result in overwriting a valid interrupt.
0b1	List register ICH_LR<n> does not contain a valid interrupt. The List register is empty and can be used without overwriting a valid interrupt or losing an EOI maintenance interrupt.

For any List register <n>, the corresponding status bit is set to 1 if ICH_LRC<n>.State is 0b00 and either ICH_LRC<n>.HW is 1 or ICH_LRC<n>.EOI (bit [9]) is 0.

Accessing the ICH_ELRSR

Accesses to this register use the following encodings:

MRC{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

opc1	opc2	CRn	coproc	CRm
0b100	0b101	0b1100	0b1111	0b1011

if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T12 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T12 == '1' then
        AArch32.TakeHypTrapException(0x03);
    else
        UNDEFINED;
elsif PSTATE.EL == EL2 then
    if ICC_HSRE.SRE == '0' then
        UNDEFINED;
    else
        return ICH_ELRSR;
elsif PSTATE.EL == EL3 then
    if ICC_MSRE.SRE == '0' then
        UNDEFINED;
    else
        return ICH_ELRSR;

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