fix(cpus): workaround for Cortex-A510 erratum 2684597

Cortex-A510 erratum 2684597 is a Cat B erratum that applies to revisions
r0p0, r0p1, r0p2, r0p3, r1p0, r1p1 and r1p2. It is fixed in r1p3. The
workaround is to execute a TSB CSYNC and DSB before executing WFI for
power down.

SDEN can be found here:
https://developer.arm.com/documentation/SDEN1873361/latest
https://developer.arm.com/documentation/SDEN1873351/latest

Change-Id: Ic0b24b600bc013eb59c797401fbdc9bda8058d6d
Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index c9b4447..9c556b6 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -736,6 +736,11 @@
 # to revisions r0p0, r0p1, r0p2, r0p3, r1p0, and r1p1. It is fixed in r1p2.
 ERRATA_A510_2666669	?=0
 
+# Flag to apply erratum 2684597 workaround during powerdown. This erratum
+# applies to revision r0p0, r0p1, r0p2, r0p3, r1p0, r1p1 and r1p2 of the
+# Cortex-A510 cpu and is fixed in r1p3.
+ERRATA_A510_2684597	?=0
+
 # Flag to apply DSU erratum 798953. This erratum applies to DSUs revision r0p0.
 # Applying the workaround results in higher DSU power consumption on idle.
 ERRATA_DSU_798953	?=0
@@ -1390,6 +1395,10 @@
 $(eval $(call assert_boolean,ERRATA_A510_2666669))
 $(eval $(call add_define,ERRATA_A510_2666669))
 
+# Process ERRATA_A510_2684597 flag
+$(eval $(call assert_boolean,ERRATA_A510_2684597))
+$(eval $(call add_define,ERRATA_A510_2684597))
+
 #Process ERRATA_DSU_798953 flag
 $(eval $(call assert_boolean,ERRATA_DSU_798953))
 $(eval $(call add_define,ERRATA_DSU_798953))