Workaround for Neoverse N1 erratum 1207823

Neoverse N1 erratum 1207823 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
CPUACTLR2_EL1 system register.

[1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.pjdoc-466751330-10325/index.html

Change-Id: Ia932337821f1ef0d644db3612480462a8d924d21
Signed-off-by: Lauren Wehrmeister <[email protected]>

diff --git a/docs/design/cpu-specific-build-macros.rst b/docs/design/cpu-specific-build-macros.rst
index fd99d8e90f4c062c7733cb274af61f011564e686..ef24f2e393ffbae93197ac4ad4e8d84c08ce39bb 100644 (file)
--- a/docs/design/cpu-specific-build-macros.rst
+++ b/docs/design/cpu-specific-build-macros.rst
@@ -237,6 +237,9 @@ For Neoverse N1, the following errata build flags are defined :
 -  ``ERRATA_N1_1165347``: This applies errata 1165347 workaround to Neoverse-N1
    CPU. This needs to be enabled only for revision <= r2p0 of the CPU.
 
+-  ``ERRATA_N1_1207823``: This applies errata 1207823 workaround to Neoverse-N1
+   CPU. This needs to be enabled only for revision <= r2p0 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 7950cd220b5fc2fca1e678397453b50dab90c0c9..8925827e93449057b2ad8d676001eb02dd7b4ac1 100644 (file)
--- a/include/lib/cpus/aarch64/neoverse_n1.h
+++ b/include/lib/cpus/aarch64/neoverse_n1.h
@@ -41,6 +41,7 @@
 
 #define NEOVERSE_N1_CPUACTLR2_EL1_BIT_0                (ULL(1) << 0)
 #define NEOVERSE_N1_CPUACTLR2_EL1_BIT_2                (ULL(1) << 2)
+#define NEOVERSE_N1_CPUACTLR2_EL1_BIT_11       (ULL(1) << 11)
 #define NEOVERSE_N1_CPUACTLR2_EL1_BIT_15       (ULL(1) << 15)
 #define NEOVERSE_N1_CPUACTLR2_EL1_BIT_16       (ULL(1) << 16)
 #define NEOVERSE_N1_CPUACTLR2_EL1_BIT_59       (ULL(1) << 59)

diff --git a/lib/cpus/aarch64/neoverse_n1.S b/lib/cpus/aarch64/neoverse_n1.S
index a8ffa254691eb0d5bdd567893314f2d386f601c6..c9bcea89819137639df347905460c504a63e4525 100644 (file)
--- a/lib/cpus/aarch64/neoverse_n1.S
+++ b/lib/cpus/aarch64/neoverse_n1.S
@@ -157,6 +157,33 @@ func check_errata_1165347
        b       cpu_rev_var_ls
 endfunc check_errata_1165347
 
+/* --------------------------------------------------
+ * Errata Workaround for Neoverse N1 Errata #1207823
+ * This applies to revision <=r2p0 of Neoverse N1.
+ * Inputs:
+ * x0: variant[4:7] and revision[0:3] of current cpu.
+ * Shall clobber: x0-x17
+ * --------------------------------------------------
+ */
+func errata_n1_1207823_wa
+       /* Compare x0 against revision r2p0 */
+       mov     x17, x30
+       bl      check_errata_1207823
+       cbz     x0, 1f
+       mrs     x1, NEOVERSE_N1_CPUACTLR2_EL1
+       orr     x1, x1, NEOVERSE_N1_CPUACTLR2_EL1_BIT_11
+       msr     NEOVERSE_N1_CPUACTLR2_EL1, x1
+       isb
+1:
+       ret     x17
+endfunc errata_n1_1207823_wa
+
+func check_errata_1207823
+       /* Applies to <=r2p0 */
+       mov     x1, #0x20
+       b       cpu_rev_var_ls
+endfunc check_errata_1207823
+
 /* --------------------------------------------------
  * Errata Workaround for Neoverse N1 Erratum 1315703.
  * This applies to revision <= r3p0 of Neoverse N1.
@@ -220,6 +247,11 @@ func neoverse_n1_reset_func
        bl      errata_n1_1165347_wa
 #endif
 
+#if ERRATA_N1_1207823
+       mov     x0, x18
+       bl      errata_n1_1207823_wa
+#endif
+
 #if ERRATA_N1_1315703
        mov     x0, x18
        bl      errata_n1_1315703_wa
@@ -285,6 +317,7 @@ func neoverse_n1_errata_report
        report_errata ERRATA_N1_1073348, neoverse_n1, 1073348
        report_errata ERRATA_N1_1130799, neoverse_n1, 1130799
        report_errata ERRATA_N1_1165347, neoverse_n1, 1165347
+       report_errata ERRATA_N1_1207823, neoverse_n1, 1207823
        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 faaf1203bf6226fec066c708dced97801ffb3140..78efbeb3c0cbfc077c7727f5a38520bc7df42b0d 100644 (file)
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -250,6 +250,10 @@ ERRATA_N1_1130799  ?=0
 # only to revision <= r2p0 of the Neoverse N1 cpu.
 ERRATA_N1_1165347      ?=0
 
+# Flag to apply erratum 1207823 workaround during reset. This erratum applies
+# only to revision <= r2p0 of the Neoverse N1 cpu.
+ERRATA_N1_1207823      ?=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
@@ -455,6 +459,10 @@ $(eval $(call add_define,ERRATA_N1_1130799))
 $(eval $(call assert_boolean,ERRATA_N1_1165347))
 $(eval $(call add_define,ERRATA_N1_1165347))
 
+# Process ERRATA_N1_1207823 flag
+$(eval $(call assert_boolean,ERRATA_N1_1207823))
+$(eval $(call add_define,ERRATA_N1_1207823))
+
 # Process ERRATA_N1_1315703 flag
 $(eval $(call assert_boolean,ERRATA_N1_1315703))
 $(eval $(call add_define,ERRATA_N1_1315703))