fix(cpus): workaround for Neoverse N2 erratum 2346952

Neoverse N2 erratum 2346952 is a Cat B erratum that applies to all
revisions <= r0p2 and is fixed in r0p3.
The workaround is to set L2 TQ size statically to it's full size.

SDEN documentation:
https://developer.arm.com/documentation/SDEN-1982442/latest

Change-Id: I03c3cf1f951fbc906fdebcb99a523c5ac8ba055d
Signed-off-by: Bipin Ravi <bipin.ravi@arm.com>

5 files changed, 30 insertions, 8 deletions

diff --git a/docs/design/cpu-specific-build-macros.rst b/docs/design/cpu-specific-build-macros.rst
index 146026b4a..0b0184076 100644
--- a/docs/design/cpu-specific-build-macros.rst
+++ b/docs/design/cpu-specific-build-macros.rst
@@ -655,6 +655,10 @@ For Neoverse N2, the following errata build flags are defined :
    CPU. This needs to be enabled for revision r0p0 of the CPU, it is fixed in
    r0p1.
 
+-  ``ERRATA_N2_2346952``: This applies errata 2346952 workaround to Neoverse-N2
+   CPU. This needs to be enabled for revisions r0p0, r0p1 and r0p2 of the CPU,
+   it is fixed in r0p3.
+
 -  ``ERRATA_N2_2376738``: This applies errata 2376738 workaround to Neoverse-N2
    CPU. This needs to be enabled for revision r0p0, r0p1, r0p2, r0p3 and is still open.
 
diff --git a/include/lib/cpus/aarch64/neoverse_n2.h b/include/lib/cpus/aarch64/neoverse_n2.h
index 0d5085433..b379faba6 100644
--- a/include/lib/cpus/aarch64/neoverse_n2.h
+++ b/include/lib/cpus/aarch64/neoverse_n2.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020-2022, Arm Limited. All rights reserved.
+ * Copyright (c) 2020-2023, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -65,5 +65,8 @@
 #define NEOVERSE_N2_CPUECTLR2_EL1_PF_MODE_CNSRV		ULL(9)
 #define CPUECTLR2_EL1_PF_MODE_LSB			U(11)
 #define CPUECTLR2_EL1_PF_MODE_WIDTH			U(4)
+#define CPUECTLR2_EL1_TXREQ_STATIC_FULL 		ULL(0)
+#define CPUECTLR2_EL1_TXREQ_LSB				U(0)
+#define CPUECTLR2_EL1_TXREQ_WIDTH			U(3)
 
 #endif /* NEOVERSE_N2_H */
diff --git a/lib/cpus/aarch64/neoverse_n2.S b/lib/cpus/aarch64/neoverse_n2.S
index ead390800..f80115177 100644
--- a/lib/cpus/aarch64/neoverse_n2.S
+++ b/lib/cpus/aarch64/neoverse_n2.S
@@ -165,6 +165,16 @@ workaround_runtime_end neoverse_n2, ERRATUM(2326639)
 
 check_erratum_ls neoverse_n2, ERRATUM(2326639), CPU_REV(0, 0)
 
+workaround_runtime_start neoverse_n2, ERRATUM(2346952), ERRATA_N2_2346952
+	/* Set TXREQ to STATIC and full L2 TQ size */
+	mrs	x1, NEOVERSE_N2_CPUECTLR2_EL1
+	mov	x0, #CPUECTLR2_EL1_TXREQ_STATIC_FULL
+	bfi	x1, x0, #CPUECTLR2_EL1_TXREQ_LSB, #CPUECTLR2_EL1_TXREQ_WIDTH
+	msr	NEOVERSE_N2_CPUECTLR2_EL1, x1
+workaround_runtime_end neoverse_n2, ERRATUM(2346952)
+
+check_erratum_ls neoverse_n2, ERRATUM(2346952), CPU_REV(0, 2)
+
 workaround_reset_start neoverse_n2, ERRATUM(2376738), ERRATA_N2_2376738
 	/* Set CPUACTLR2_EL1[0] to 1 to force PLDW/PFRM
 	 * ST to behave like PLD/PFRM LD and not cause
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index ea2904724..92c6aa491 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -660,6 +660,10 @@ CPU_FLAG_LIST += ERRATA_N2_2280757
 # applies to revision r0p0 of the Neoverse N2 cpu and is fixed in r0p1.
 CPU_FLAG_LIST += ERRATA_N2_2326639
 
+# Flag to apply erratum 2346952 workaround during reset. This erratum applies
+# to r0p0, r0p1, r0p2 of the Neoverse N2 cpu, it is fixed in r0p3.
+CPU_FLAG_LIST += ERRATA_N2_2346952
+
 # Flag to apply erratum 2376738 workaround during reset. This erratum applies
 # to revision r0p0, r0p1, r0p2, r0p3 of the Neoverse N2 cpu and is still open.
 CPU_FLAG_LIST += ERRATA_N2_2376738
diff --git a/services/std_svc/errata_abi/errata_abi_main.c b/services/std_svc/errata_abi/errata_abi_main.c
index 38ba638d0..06c38721f 100644
--- a/services/std_svc/errata_abi/errata_abi_main.c
+++ b/services/std_svc/errata_abi/errata_abi_main.c
@@ -350,14 +350,15 @@ struct em_cpu_list cpu_list[] = {
 		[9] = {2242415, 0x00, 0x00, ERRATA_N2_2242415},
 		[10] = {2280757, 0x00, 0x00, ERRATA_N2_2280757},
 		[11] = {2326639, 0x00, 0x00, ERRATA_N2_2326639},
-		[12] = {2376738, 0x00, 0x03, ERRATA_N2_2376738},
-		[13] = {2388450, 0x00, 0x00, ERRATA_N2_2388450},
-		[14] = {2728475, 0x00, 0x02, ERRATA_N2_2728475, \
+		[12] = {2346952, 0x00, 0x02, ERRATA_N2_2346952},
+		[13] = {2376738, 0x00, 0x00, ERRATA_N2_2376738},
+		[14] = {2388450, 0x00, 0x00, ERRATA_N2_2388450},
+		[15] = {2728475, 0x00, 0x02, ERRATA_N2_2728475, \
 			ERRATA_NON_ARM_INTERCONNECT},
-		[15] = {2743014, 0x00, 0x02, ERRATA_N2_2743014},
-		[16] = {2743089, 0x00, 0x02, ERRATA_N2_2743089},
-		[17] = {2779511, 0x00, 0x02, ERRATA_N2_2779511},
-		[18 ... ERRATA_LIST_END] = UNDEF_ERRATA,
+		[16] = {2743014, 0x00, 0x02, ERRATA_N2_2743014},
+		[17] = {2743089, 0x00, 0x02, ERRATA_N2_2743089},
+		[18] = {2779511, 0x00, 0x02, ERRATA_N2_2779511},
+		[19 ... ERRATA_LIST_END] = UNDEF_ERRATA,
 	}
 },
 #endif /* NEOVERSE_N2_H_INC */