CNTHCTL

Controls the generation of an event stream from the physical counter, and access from Non-secure EL1 modes to the physical counter and the Non-secure EL1 physical timer.

Configuration

AArch32 System register CNTHCTL bits [31:0] are architecturally mapped to AArch64 System register CNTHCTL_EL2[31:0].

This register is present only when EL2 is capable of using AArch32. Otherwise, direct accesses to CNTHCTL are UNDEFINED.

Attributes

Field descriptions

Bits [31:18]

EVNTIS, bit [17]
When FEAT_ECV is implemented:

Controls the scale of the generation of the event stream.

EVNTIS	Meaning
0b0	The CNTHCTL.EVNTI field applies to CNTPCT[15:0].
0b1	The CNTHCTL.EVNTI field applies to CNTPCT[23:8].

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

Otherwise:

Bits [16:8]

EVNTI, bits [7:4]

Selects which bit of CNTPCT, as seen from EL2, is the trigger for the event stream generated from that counter when that stream is enabled.

If FEAT_ECV is implemented, and CNTHCTL.EVNTIS is 1, this field selects a trigger bit in the range 8 to 23 of CNTPCT.

Otherwise, this field selects a trigger bit in the range 0 to 15 of CNTPCT.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

EVNTDIR, bit [3]

Controls which transition of the CNTPCT trigger bit, as seen from EL2 and defined by EVNTI, generates an event when the event stream is enabled.

EVNTDIR	Meaning
0b0	A 0 to 1 transition of the trigger bit triggers an event.
0b1	A 1 to 0 transition of the trigger bit triggers an event.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

EVNTEN, bit [2]

Enables the generation of an event stream from CNTPCT as seen from EL2.

EVNTEN	Meaning
0b0	Disables the event stream.
0b1	Enables the event stream.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

PL1PCEN, bit [1]

Traps Non-secure EL0 and EL1 accesses to the physical timer registers to Hyp mode.

PL1PCEN	Meaning
0b0	Non-secure EL0 and EL1 accesses to the CNTP_CTL, CNTP_CVAL, and CNTP_TVAL are trapped to Hyp mode, unless the it is trapped by CNTKCTL.PL0PTEN.
0b1	This control does not cause any instructions to be trapped.

If EL3 is implemented and EL2 is not implemented, behavior is as if this bit is 1 other than for the purpose of a direct read.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

PL1PCTEN, bit [0]

Traps Non-secure EL0 and EL1 accesses to the physical counter register to Hyp mode.

PL1PCTEN	Meaning
0b0	Non-secure EL0 and EL1 accesses to the CNTPCT are trapped to Hyp mode, unless it is trapped by CNTKCTL.PL0PCTEN.
0b1	This control does not cause any instructions to be trapped.

If EL3 is implemented and EL2 is not implemented, behavior is as if this bit is 1 other than for the purpose of a direct read.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

Accessing CNTHCTL

Accesses to this register use the following encodings in the System register encoding space:

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

coproc	opc1	CRn	CRm	opc2
0b1111	0b100	0b1110	0b0001	0b000

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then UNDEFINED; elsif PSTATE.EL == EL2 then R[t] = CNTHCTL; elsif PSTATE.EL == EL3 then if SCR.NS == '0' then UNDEFINED; else R[t] = CNTHCTL;

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

coproc	opc1	CRn	CRm	opc2
0b1111	0b100	0b1110	0b0001	0b000

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then UNDEFINED; elsif PSTATE.EL == EL2 then CNTHCTL = R[t]; elsif PSTATE.EL == EL3 then if SCR.NS == '0' then UNDEFINED; else CNTHCTL = R[t];

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
RES0														EVNTIS	RES0									EVNTI				EVNTDIR	EVNTEN	PL1PCEN	PL1PCTEN

CNTHCTL, Counter-timer Hyp Control register

Purpose

Configuration

Attributes

Field descriptions

Bits [31:18]

EVNTIS, bit [17]
When FEAT_ECV is implemented:

Otherwise:

Bits [16:8]

EVNTI, bits [7:4]

EVNTDIR, bit [3]

EVNTEN, bit [2]

PL1PCEN, bit [1]

PL1PCTEN, bit [0]

Accessing CNTHCTL

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

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

CNTHCTL, Counter-timer Hyp Control register

Purpose

Configuration

Attributes

Field descriptions

Bits [31:18]

EVNTIS, bit [17]When FEAT_ECV is implemented:

Otherwise:

Bits [16:8]

EVNTI, bits [7:4]

EVNTDIR, bit [3]

EVNTEN, bit [2]

PL1PCEN, bit [1]

PL1PCTEN, bit [0]

Accessing CNTHCTL

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

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

EVNTIS, bit [17]
When FEAT_ECV is implemented: