From 1cafb08debe7cb99968b38a070d25fee0cc9316d Mon Sep 17 00:00:00 2001 From: Bipin Ravi Date: Wed, 1 Sep 2021 01:36:43 -0500 Subject: [PATCH] errata: workaround for Neoverse N2 erratum 2138956 Neoverse N2 erratum 2138956 is a Cat B erratum that applies to revision r0p0 and is still open. This erratum can be avoided by inserting a sequence of 16 DMB ST instructions prior to WFI or WFE. SDEN can be found here: https://developer.arm.com/documentation/SDEN1982442/latest Signed-off-by: Bipin Ravi Change-Id: I1aac87b3075992f875451e4767b21857f596d0b2 --- docs/design/cpu-specific-build-macros.rst | 6 ++- lib/cpus/aarch64/neoverse_n2.S | 49 +++++++++++++++++++++++ lib/cpus/cpu-ops.mk | 8 ++++ 3 files changed, 61 insertions(+), 2 deletions(-) diff --git a/docs/design/cpu-specific-build-macros.rst b/docs/design/cpu-specific-build-macros.rst index 32df862b9..bb1bf7bcc 100644 --- a/docs/design/cpu-specific-build-macros.rst +++ b/docs/design/cpu-specific-build-macros.rst @@ -395,8 +395,10 @@ For Neoverse N2, the following errata build flags are defined : CPU. This needs to be enabled for revision r0p0 of the CPU and is still open. - ``ERRATA_N2_2189731``: This applies errata 2189731 workaround to Neoverse-N2 - CPU. This needs to be enabled only for revision r0p0 of the CPU and is still - open. + CPU. This needs to be enabled for revision r0p0 of the CPU and is still open. + +- ``ERRATA_N2_2138956``: This applies errata 2138956 workaround to Neoverse-N2 + CPU. This needs to be enabled for revision r0p0 of the CPU and is still open. DSU Errata Workarounds ---------------------- diff --git a/lib/cpus/aarch64/neoverse_n2.S b/lib/cpus/aarch64/neoverse_n2.S index 0df40766e..9e7bbf7e6 100644 --- a/lib/cpus/aarch64/neoverse_n2.S +++ b/lib/cpus/aarch64/neoverse_n2.S @@ -141,6 +141,48 @@ func check_errata_2189731 b cpu_rev_var_ls endfunc check_errata_2189731 +/* -------------------------------------------------- + * Errata Workaround for Neoverse N2 Erratum 2138956. + * This applies to revision r0p0 of Neoverse N2. it is still open. + * Inputs: + * x0: variant[4:7] and revision[0:3] of current cpu. + * Shall clobber: x0-x17 + * -------------------------------------------------- + */ +func errata_n2_2138956_wa + /* Check revision. */ + mov x17, x30 + bl check_errata_2138956 + cbz x0, 1f + + /* Apply instruction patching sequence */ + ldr x0,=0x3 + msr S3_6_c15_c8_0,x0 + ldr x0,=0xF3A08002 + msr S3_6_c15_c8_2,x0 + ldr x0,=0xFFF0F7FE + msr S3_6_c15_c8_3,x0 + ldr x0,=0x10002001003FF + msr S3_6_c15_c8_1,x0 + ldr x0,=0x4 + msr S3_6_c15_c8_0,x0 + ldr x0,=0xBF200000 + msr S3_6_c15_c8_2,x0 + ldr x0,=0xFFEF0000 + msr S3_6_c15_c8_3,x0 + ldr x0,=0x10002001003F3 + msr S3_6_c15_c8_1,x0 + isb +1: + ret x17 +endfunc errata_n2_2138956_wa + +func check_errata_2138956 + /* Applies to r0p0 */ + mov x1, #0x00 + b cpu_rev_var_ls +endfunc check_errata_2138956 + /* ------------------------------------------- * The CPU Ops reset function for Neoverse N2. * ------------------------------------------- @@ -176,6 +218,12 @@ func neoverse_n2_reset_func bl errata_n2_2189731_wa #endif + +#if ERRATA_N2_2138956 + mov x0, x18 + bl errata_n2_2138956_wa +#endif + #if ENABLE_AMU /* Make sure accesses from EL0/EL1 and EL2 are not trapped to EL3 */ mrs x0, cptr_el3 @@ -240,6 +288,7 @@ func neoverse_n2_errata_report report_errata ERRATA_N2_2067956, neoverse_n2, 2067956 report_errata ERRATA_N2_2025414, neoverse_n2, 2025414 report_errata ERRATA_N2_2189731, neoverse_n2, 2189731 + report_errata ERRATA_N2_2138956, neoverse_n2, 2138956 ldp x8, x30, [sp], #16 ret diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk index e0fc1f7c7..584682edf 100644 --- a/lib/cpus/cpu-ops.mk +++ b/lib/cpus/cpu-ops.mk @@ -433,6 +433,10 @@ ERRATA_N2_2025414 ?=0 # to revision r0p0 of the Neoverse N2 cpu and is still open. ERRATA_N2_2189731 ?=0 +# Flag to apply erratum 2138956 workaround during reset. This erratum applies +# to revision r0p0 of the Neoverse N2 cpu and is still open. +ERRATA_N2_2138956 ?=0 + # Flag to apply erratum 2055002 workaround during reset. This erratum applies # to revision r1p0, r2p0 of the Cortex-A710 cpu and is still open. ERRATA_A710_2055002 ?=0 @@ -806,6 +810,10 @@ $(eval $(call add_define,ERRATA_N2_2025414)) $(eval $(call assert_boolean,ERRATA_N2_2189731)) $(eval $(call add_define,ERRATA_N2_2189731)) +# Process ERRATA_N2_2138956 flag +$(eval $(call assert_boolean,ERRATA_N2_2138956)) +$(eval $(call add_define,ERRATA_N2_2138956)) + # Process ERRATA_A710_2055002 flag $(eval $(call assert_boolean,ERRATA_A710_2055002)) $(eval $(call add_define,ERRATA_A710_2055002))