Workaround for Neoverse N1 erratum 1257314
Neoverse N1 erratum 1257314 is a Cat B erratum [1],
present in older revisions of the Neoverse N1 processor core.
The workaround is to set a bit in the implementation defined
CPUACTLR3_EL1 system register, which prevents parallel
execution of divide and square root instructions.
[1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.pjdoc-466751330-10325/index.html
Change-Id: I54f0f40ff9043efee40d51e796b92ed85b394cbb
Signed-off-by: Lauren Wehrmeister <lauren.wehrmeister@arm.com>
diff --git a/docs/design/cpu-specific-build-macros.rst b/docs/design/cpu-specific-build-macros.rst
index ee8da17..14dfe95 100644
--- a/docs/design/cpu-specific-build-macros.rst
+++ b/docs/design/cpu-specific-build-macros.rst
@@ -243,6 +243,9 @@
- ``ERRATA_N1_1220197``: This applies errata 1220197 workaround to Neoverse-N1
CPU. This needs to be enabled only for revision <= r2p0 of the CPU.
+- ``ERRATA_N1_1257314``: This applies errata 1257314 workaround to Neoverse-N1
+ CPU. This needs to be enabled only for revision <= r3p0 of the CPU.
+
- ``ERRATA_N1_1315703``: This applies errata 1315703 workaround to Neoverse-N1
CPU. This needs to be enabled only for revision <= r3p0 of the CPU.
diff --git a/include/lib/cpus/aarch64/neoverse_n1.h b/include/lib/cpus/aarch64/neoverse_n1.h
index 952ae6e..0e9ddb8 100644
--- a/include/lib/cpus/aarch64/neoverse_n1.h
+++ b/include/lib/cpus/aarch64/neoverse_n1.h
@@ -48,6 +48,9 @@
#define NEOVERSE_N1_CPUACTLR2_EL1_BIT_16 (ULL(1) << 16)
#define NEOVERSE_N1_CPUACTLR2_EL1_BIT_59 (ULL(1) << 59)
+#define NEOVERSE_N1_CPUACTLR3_EL1 S3_0_C15_C1_2
+
+#define NEOVERSE_N1_CPUACTLR3_EL1_BIT_10 (ULL(1) << 10)
/* Instruction patching registers */
#define CPUPSELR_EL3 S3_6_C15_C8_0
diff --git a/lib/cpus/aarch64/neoverse_n1.S b/lib/cpus/aarch64/neoverse_n1.S
index 0e7b8e8..19b21a5 100644
--- a/lib/cpus/aarch64/neoverse_n1.S
+++ b/lib/cpus/aarch64/neoverse_n1.S
@@ -212,6 +212,33 @@
endfunc check_errata_1220197
/* --------------------------------------------------
+ * Errata Workaround for Neoverse N1 Errata #1257314
+ * This applies to revision <=r3p0 of Neoverse N1.
+ * Inputs:
+ * x0: variant[4:7] and revision[0:3] of current cpu.
+ * Shall clobber: x0-x17
+ * --------------------------------------------------
+ */
+func errata_n1_1257314_wa
+ /* Compare x0 against revision r3p0 */
+ mov x17, x30
+ bl check_errata_1257314
+ cbz x0, 1f
+ mrs x1, NEOVERSE_N1_CPUACTLR3_EL1
+ orr x1, x1, NEOVERSE_N1_CPUACTLR3_EL1_BIT_10
+ msr NEOVERSE_N1_CPUACTLR3_EL1, x1
+ isb
+1:
+ ret x17
+endfunc errata_n1_1257314_wa
+
+func check_errata_1257314
+ /* Applies to <=r3p0 */
+ mov x1, #0x30
+ b cpu_rev_var_ls
+endfunc check_errata_1257314
+
+/* --------------------------------------------------
* Errata Workaround for Neoverse N1 Erratum 1315703.
* This applies to revision <= r3p0 of Neoverse N1.
* Inputs:
@@ -284,6 +311,11 @@
bl errata_n1_1220197_wa
#endif
+#if ERRATA_N1_1257314
+ mov x0, x18
+ bl errata_n1_1257314_wa
+#endif
+
#if ERRATA_N1_1315703
mov x0, x18
bl errata_n1_1315703_wa
@@ -351,6 +383,7 @@
report_errata ERRATA_N1_1165347, neoverse_n1, 1165347
report_errata ERRATA_N1_1207823, neoverse_n1, 1207823
report_errata ERRATA_N1_1220197, neoverse_n1, 1220197
+ report_errata ERRATA_N1_1257314, neoverse_n1, 1257314
report_errata ERRATA_N1_1315703, neoverse_n1, 1315703
report_errata ERRATA_DSU_936184, neoverse_n1, dsu_936184
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index bb53dad..c4769d9 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -258,6 +258,10 @@
# only to revision <= r2p0 of the Neoverse N1 cpu.
ERRATA_N1_1220197 ?=0
+# Flag to apply erratum 1257314 workaround during reset. This erratum applies
+# only to revision <= r3p0 of the Neoverse N1 cpu.
+ERRATA_N1_1257314 ?=0
+
# Flag to apply erratum 1315703 workaround during reset. This erratum applies
# to revisions before r3p1 of the Neoverse N1 cpu.
ERRATA_N1_1315703 ?=1
@@ -471,6 +475,10 @@
$(eval $(call assert_boolean,ERRATA_N1_1220197))
$(eval $(call add_define,ERRATA_N1_1220197))
+# Process ERRATA_N1_1257314 flag
+$(eval $(call assert_boolean,ERRATA_N1_1257314))
+$(eval $(call add_define,ERRATA_N1_1257314))
+
# Process ERRATA_N1_1315703 flag
$(eval $(call assert_boolean,ERRATA_N1_1315703))
$(eval $(call add_define,ERRATA_N1_1315703))