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ARM Cortex-A72 MPCore Processor Technical Reference Manual : L2 Extended Control Register, EL1

Extended Control Register, EL1

The L2ECTLR_EL1 characteristics are:

Purpose
Provides additional IMPLEMENTATION DEFINED control options for the L2 memory system. There is one L2 Extended Control Register for the Cortex-A72 processor.
Usage constraints

The accessibility to the L2ECTLR_EL1 by Exception level is:

EL0 EL1(NS) EL1(S) EL2 EL3(SCR.NS = 1) EL3(SCR.NS = 0)
- RWa RWa RWb RW RW

The L2ECTLR_EL1 can be written dynamically.

Configurations

The L2ECTLR_EL1 is:

  • Common to the Secure and Non-secure states.
  • 32-bit register in AArch64 state.
  • Architecturally mapped to the AArch32 L2ECTLR register.
Attributes
See the register summary in Table 4-15 AArch64 IMPLEMENTATION DEFINED registers.

The following figure shows the L2ECTLR bit assignments.

Figure 4-51 L2ECTLR_EL1 bit assignments


The following table shows the L2ECTLR_EL1 bit assignments.

Table 4-70 L2ECTLR_EL1 bit assignments

Bits Name Function
[31] - Reserved, RES0.
[30] internal asynchronous error

L2 internal asynchronous error caused by L2 RAM double-bit ECC error. The possible values are:

0No pending asynchronous error. This is the reset value.
1An asynchronous error has occurred.

A write of 0 clears this bit. A write of 1 is ignored.

[29] AXI or CHI asynchronous error

AXI or CHI asynchronous error indication. The possible values are:

0No pending asynchronous error. This is the reset value.
1An asynchronous error has occurred.

A write of 0 clears this bit. A write of 1 is ignored.

[28:3] - Reserved, RES0.
[2:0] L2 dynamic retention control

L2 dynamic retention control. The possible values are:

0b000L2 dynamic retention disabled. This is the reset value.
0b0012 Generic Timer ticks required before retention entry.
0b0108 Generic Timer ticks required before retention entry.
0b01132 Generic Timer ticks required before retention entry.
0b10064 Generic Timer ticks required before retention entry.
0b101128 Generic Timer ticks required before retention entry.
0b110256 Generic Timer ticks required before retention entry.
0b111512 Generic Timer ticks required before retention entry.

To access the L2ECTLR_EL1 in AArch32 state, read or write the CP15 register with:

MRS <Xt>, S3_1_c11_c0_3; Read L2 Extended Control Register
MSR S3_1_c11_c0_3, <Xt>; Write L2 Extended Control Register

To access the L2ECTLR in AArch32 state, read or write the CP15 register with:

MRC p15, 1, <Rt>, c9, c0, 3; Read L2 Extended Control Register
MCR p15, 1, <Rt>, c9, c0, 3; Write L2 Extended Control Register

Related information

a Write access if ACTLR_EL3.L2ECTLR is 1 and ACTLR_EL2.L2ECTLR is 1, or ACTLR_EL3.L2ECTLR is 1 and the Secure SCR.NS is 0.
b Write access if ACTLR_EL3.L2ECTLR is 1.