Workaround for Cortex A78 erratum 1951500
Cortex A78 erratum 1951500 is a Cat B erratum that applies to revisions
r0p0, r1p0, and r1p1. The workaround is to insert a DMB ST before
acquire atomic instructions without release semantics. This workaround
works on revisions r1p0 and r1p1, in r0p0 there is no workaround.
SDEN can be found here:
https://documentation-service.arm.com/static/5fb66157ca04df4095c1cc2e
Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: I47610cee75af6a127ea65edc4d5cffc7e6a2d0a3
diff --git a/lib/cpus/aarch64/cortex_a78.S b/lib/cpus/aarch64/cortex_a78.S
index ef760ed..f61726b 100644
--- a/lib/cpus/aarch64/cortex_a78.S
+++ b/lib/cpus/aarch64/cortex_a78.S
@@ -72,6 +72,60 @@
b cpu_rev_var_ls
endfunc check_errata_1941498
+ /* --------------------------------------------------
+ * Errata Workaround for A78 Erratum 1951500.
+ * This applies to revisions r1p0 and r1p1 of A78.
+ * The issue also exists in r0p0 but there is no fix
+ * in that revision.
+ * Inputs:
+ * x0: variant[4:7] and revision[0:3] of current cpu.
+ * Shall clobber: x0-x17
+ * --------------------------------------------------
+ */
+func errata_a78_1951500_wa
+ /* Compare x0 against revisions r1p0 - r1p1 */
+ mov x17, x30
+ bl check_errata_1951500
+ cbz x0, 1f
+
+ msr S3_6_c15_c8_0, xzr
+ ldr x0, =0x10E3900002
+ msr S3_6_c15_c8_2, x0
+ ldr x0, =0x10FFF00083
+ msr S3_6_c15_c8_3, x0
+ ldr x0, =0x2001003FF
+ msr S3_6_c15_c8_1, x0
+
+ mov x0, #1
+ msr S3_6_c15_c8_0, x0
+ ldr x0, =0x10E3800082
+ msr S3_6_c15_c8_2, x0
+ ldr x0, =0x10FFF00083
+ msr S3_6_c15_c8_3, x0
+ ldr x0, =0x2001003FF
+ msr S3_6_c15_c8_1, x0
+
+ mov x0, #2
+ msr S3_6_c15_c8_0, x0
+ ldr x0, =0x10E3800200
+ msr S3_6_c15_c8_2, x0
+ ldr x0, =0x10FFF003E0
+ msr S3_6_c15_c8_3, x0
+ ldr x0, =0x2001003FF
+ msr S3_6_c15_c8_1, x0
+
+ isb
+1:
+ ret x17
+endfunc errata_a78_1951500_wa
+
+func check_errata_1951500
+ /* Applies to revisions r1p0 and r1p1. */
+ mov x1, #CPU_REV(1, 0)
+ mov x2, #CPU_REV(1, 1)
+ b cpu_rev_var_range
+endfunc check_errata_1951500
+
/* -------------------------------------------------
* The CPU Ops reset function for Cortex-A78
* -------------------------------------------------
@@ -91,6 +145,11 @@
bl errata_a78_1941498_wa
#endif
+#if ERRATA_A78_1951500
+ mov x0, x18
+ bl errata_a78_1951500_wa
+#endif
+
#if ENABLE_AMU
/* Make sure accesses from EL0/EL1 and EL2 are not trapped to EL3 */
mrs x0, actlr_el3
@@ -147,6 +206,7 @@
*/
report_errata ERRATA_A78_1688305, cortex_a78, 1688305
report_errata ERRATA_A78_1941498, cortex_a78, 1941498
+ report_errata ERRATA_A78_1951500, cortex_a78, 1951500
ldp x8, x30, [sp], #16
ret
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index b7dec0b..93b538c 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -298,6 +298,11 @@
# to revisions r0p0, r1p0, and r1p1 of the A78 cpu.
ERRATA_A78_1941498 ?=0
+# Flag to apply erratum 1951500 workaround during reset. This erratum applies
+# to revisions r1p0 and r1p1 of the A78 cpu. The issue is present in r0p0 as
+# well but there is no workaround for that revision.
+ERRATA_A78_1951500 ?=0
+
# Flag to apply T32 CLREX workaround during reset. This erratum applies
# only to r0p0 and r1p0 of the Neoverse N1 cpu.
ERRATA_N1_1043202 ?=0
@@ -583,6 +588,10 @@
$(eval $(call assert_boolean,ERRATA_A78_1941498))
$(eval $(call add_define,ERRATA_A78_1941498))
+# Process ERRATA_A78_1951500 flag
+$(eval $(call assert_boolean,ERRATA_A78_1951500))
+$(eval $(call add_define,ERRATA_A78_1951500))
+
# Process ERRATA_N1_1043202 flag
$(eval $(call assert_boolean,ERRATA_N1_1043202))
$(eval $(call add_define,ERRATA_N1_1043202))