fix(errata): workaround for Neoverse-N2 erratum 2138953
Neoverse-N2 erratum 2138953 is a Cat B erratum that applies to
revision r0p0 of CPU. It is still open. The workaround
is to write the value 4'b1001 to the PF_MODE bits in the
IMP_CPUECTLR2_EL1 register which will place the data prefetcher
in the most conservative mode instead of disabling it.
SDEN can be found here:
https://developer.arm.com/documentation/SDEN1982442/latest
Signed-off-by: nayanpatel-arm <nayankumar.patel@arm.com>
Change-Id: Ife0a4bece7ccf83cc99c1d5f5b5a43084bb69d64
diff --git a/lib/cpus/aarch64/neoverse_n2.S b/lib/cpus/aarch64/neoverse_n2.S
index 9e7bbf7..330cc59 100644
--- a/lib/cpus/aarch64/neoverse_n2.S
+++ b/lib/cpus/aarch64/neoverse_n2.S
@@ -183,6 +183,35 @@
b cpu_rev_var_ls
endfunc check_errata_2138956
+/* --------------------------------------------------
+ * Errata Workaround for Neoverse N2 Erratum 2138953.
+ * 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-x1, x17
+ * --------------------------------------------------
+ */
+func errata_n2_2138953_wa
+ /* Check revision. */
+ mov x17, x30
+ bl check_errata_2138953
+ cbz x0, 1f
+
+ /* Apply instruction patching sequence */
+ mrs x1, NEOVERSE_N2_CPUECTLR2_EL1
+ mov x0, #NEOVERSE_N2_CPUECTLR2_EL1_PF_MODE_CNSRV
+ bfi x1, x0, #CPUECTLR2_EL1_PF_MODE_LSB, #CPUECTLR2_EL1_PF_MODE_WIDTH
+ msr NEOVERSE_N2_CPUECTLR2_EL1, x1
+1:
+ ret x17
+endfunc errata_n2_2138953_wa
+
+func check_errata_2138953
+ /* Applies to r0p0 */
+ mov x1, #0x00
+ b cpu_rev_var_ls
+endfunc check_errata_2138953
+
/* -------------------------------------------
* The CPU Ops reset function for Neoverse N2.
* -------------------------------------------
@@ -224,6 +253,11 @@
bl errata_n2_2138956_wa
#endif
+#if ERRATA_N2_2138953
+ mov x0, x18
+ bl errata_n2_2138953_wa
+#endif
+
#if ENABLE_AMU
/* Make sure accesses from EL0/EL1 and EL2 are not trapped to EL3 */
mrs x0, cptr_el3
@@ -287,8 +321,9 @@
report_errata ERRATA_N2_2002655, neoverse_n2, 2002655
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_2189731, neoverse_n2, 2189731
report_errata ERRATA_N2_2138956, neoverse_n2, 2138956
+ report_errata ERRATA_N2_2138953, neoverse_n2, 2138953
ldp x8, x30, [sp], #16
ret