errata: workaround for Neoverse-N2 errata 2002655
Neoverse-N2 erratum 2002655 is a Cat B erratum present in r0p0 of
the Neoverse-N2 processor core, and it is still open.
Neoverse-N2 SDEN: https://documentation-service.arm.com/static/61098b4e3d73a34b640e32c9?token=
Signed-off-by: nayanpatel-arm <nayankumar.patel@arm.com>
Change-Id: I1380418146807527abd97cdd4918265949ba5c01
diff --git a/docs/design/cpu-specific-build-macros.rst b/docs/design/cpu-specific-build-macros.rst
index 2dfaf78..b2b751f 100644
--- a/docs/design/cpu-specific-build-macros.rst
+++ b/docs/design/cpu-specific-build-macros.rst
@@ -333,6 +333,11 @@
CPU. This needs to be enabled for revisions r3p0, r3p1, r4p0, and r4p1, for
revisions r0p0, r1p0, and r2p0 there is no workaround.
+For Neoverse N2, the following errata build flags are defined :
+
+- ``ERRATA_N2_2002655``: This applies errata 2002655 workaround to Neoverse-N2
+ CPU. This needs to be enabled for revision r0p0 of the CPU, it is still open.
+
For Neoverse V1, the following errata build flags are defined :
- ``ERRATA_V1_1774420``: This applies errata 1774420 workaround to Neoverse-V1
diff --git a/lib/cpus/aarch64/neoverse_n2.S b/lib/cpus/aarch64/neoverse_n2.S
index 8d646cb..44db0b3 100644
--- a/lib/cpus/aarch64/neoverse_n2.S
+++ b/lib/cpus/aarch64/neoverse_n2.S
@@ -19,11 +19,55 @@
#error "Neoverse-N2 supports only AArch64. Compile with CTX_INCLUDE_AARCH32_REGS=0"
#endif
+/* --------------------------------------------------
+ * Errata Workaround for Neoverse N2 Erratum 2002655.
+ * 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_2002655_wa
+ /* Check revision. */
+ mov x17, x30
+ bl check_errata_2002655
+ cbz x0, 1f
+
+ /* Apply instruction patching sequence */
+ ldr x0,=0x6
+ 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,=0x40000001003ff
+ msr S3_6_c15_c8_1,x0
+ ldr x0,=0x7
+ 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,=0x40000001003f3
+ msr S3_6_c15_c8_1,x0
+ isb
+1:
+ ret x17
+endfunc errata_n2_2002655_wa
+
+func check_errata_2002655
+ /* Applies to r0p0 */
+ mov x1, #0x00
+ b cpu_rev_var_ls
+endfunc check_errata_2002655
+
/* -------------------------------------------------
* The CPU Ops reset function for Neoverse N2.
* -------------------------------------------------
*/
func neoverse_n2_reset_func
+ mov x19, x30
+
/* Check if the PE implements SSBS */
mrs x0, id_aa64pfr1_el1
tst x0, #(ID_AA64PFR1_EL1_SSBS_MASK << ID_AA64PFR1_EL1_SSBS_SHIFT)
@@ -58,8 +102,16 @@
msr NEOVERSE_N2_CPUECTLR_EL1, x0
#endif
+ bl cpu_get_rev_var
+ mov x18, x0
+
+#if ERRATA_N2_2002655
+ mov x0, x18
+ bl errata_n2_2002655_wa
+#endif
+
isb
- ret
+ ret x19
endfunc neoverse_n2_reset_func
func neoverse_n2_core_pwr_dwn
@@ -80,7 +132,18 @@
* Errata printing function for Neoverse N2 cores. Must follow AAPCS.
*/
func neoverse_n2_errata_report
- /* No errata reported for Neoverse N2 cores */
+ stp x8, x30, [sp, #-16]!
+
+ bl cpu_get_rev_var
+ mov x8, x0
+
+ /*
+ * Report all errata. The revision-variant information is passed to
+ * checking functions of each errata.
+ */
+ report_errata ERRATA_N2_2002655, neoverse_n2, 2002655
+
+ ldp x8, x30, [sp], #16
ret
endfunc neoverse_n2_errata_report
#endif
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index e81471e..a46d3b6 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -380,6 +380,10 @@
# exists in revisions r0p0, r1p0, and r2p0 as well but there is no workaround.
ERRATA_N1_1946160 ?=0
+# Flag to apply erratum 2002655 workaround during reset. This erratum applies
+# to revisions r0p0 of the Neoverse-N2 cpu, it is still open.
+ERRATA_N2_2002655 ?=0
+
# Flag to apply erratum 1774420 workaround during reset. This erratum applies
# to revisions r0p0 and r1p0 of the Neoverse V1 core, and was fixed in r1p1.
ERRATA_V1_1774420 ?=0
@@ -722,6 +726,10 @@
$(eval $(call assert_boolean,ERRATA_N1_1946160))
$(eval $(call add_define,ERRATA_N1_1946160))
+# Process ERRATA_N2_2002655 flag
+$(eval $(call assert_boolean,ERRATA_N2_2002655))
+$(eval $(call add_define,ERRATA_N2_2002655))
+
# Process ERRATA_V1_1774420 flag
$(eval $(call assert_boolean,ERRATA_V1_1774420))
$(eval $(call add_define,ERRATA_V1_1774420))