fix(cpus): workaround for Neoverse N2 erratum 2009478
Neoverse N2 erratum 2009478 is a Cat B erratum that applies to
revision r0p0 and is fixed in r0p1. The workaround is to clear
the ED bit for all core error records before setting the PWRDN_EN
bit in CPUPWRCTLR_EL1 to request a power down.
SDEN documentation:
https://developer.arm.com/documentation/SDEN1982442/latest
Signed-off-by: Bipin Ravi <bipin.ravi@arm.com>
Change-Id: Ic5ef58c9e795b90026af1d2b09edc0eea3ceee51
diff --git a/lib/cpus/aarch64/neoverse_n2.S b/lib/cpus/aarch64/neoverse_n2.S
index acf8dee..ead3908 100644
--- a/lib/cpus/aarch64/neoverse_n2.S
+++ b/lib/cpus/aarch64/neoverse_n2.S
@@ -68,6 +68,22 @@
check_erratum_ls neoverse_n2, ERRATUM(2067956), CPU_REV(0, 0)
+workaround_runtime_start neoverse_n2, ERRATUM(2009478), ERRATA_N2_2009478
+ /* Stash ERRSELR_EL1 in x2 */
+ mrs x2, ERRSELR_EL1
+
+ /* Select error record 0 and clear ED bit */
+ msr ERRSELR_EL1, xzr
+ mrs x1, ERXCTLR_EL1
+ bfi x1, xzr, #ERXCTLR_ED_SHIFT, #1
+ msr ERXCTLR_EL1, x1
+
+ /* Restore ERRSELR_EL1 from x2 */
+ msr ERRSELR_EL1, x2
+workaround_runtime_end neoverse_n2, ERRATUM(2009478), NO_ISB
+
+check_erratum_ls neoverse_n2, ERRATUM(2009478), CPU_REV(0, 0)
+
workaround_reset_start neoverse_n2, ERRATUM(2138953), ERRATA_N2_2138953
/* Apply instruction patching sequence */
mrs x1, NEOVERSE_N2_CPUECTLR2_EL1
@@ -233,7 +249,9 @@
func neoverse_n2_core_pwr_dwn
- apply_erratum neoverse_n2, ERRATUM(2326639), ERRATA_N2_2326639
+ apply_erratum neoverse_n2, ERRATUM(2009478), ERRATA_N2_2009478
+ apply_erratum neoverse_n2, ERRATUM(2326639), ERRATA_N2_2326639, NO_GET_CPU_REV
+
/* ---------------------------------------------------
* Enable CPU power down bit in power control register
* No need to do cache maintenance here.
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index 8df0a29..88ef8a7 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -615,6 +615,10 @@
# to revisions r0p0 of the Neoverse-N2 cpu and is fixed in r0p1.
CPU_FLAG_LIST += ERRATA_N2_2002655
+# Flag to apply erratum 2009478 workaround during powerdown. This erratum
+# applies to revision r0p0 of the Neoverse N2 cpu, it is fixed in r0p1.
+CPU_FLAG_LIST += ERRATA_N2_2009478
+
# Flag to apply erratum 2067956 workaround during reset. This erratum applies
# to revision r0p0 of the Neoverse N2 cpu and is fixed in r0p1.
CPU_FLAG_LIST += ERRATA_N2_2067956