fix(errata): workaround for DSU-110 erratum 2313941
DSU-110 erratum 2313941 is a Cat B erratum and applies to revisions
r0p0, r1p0, r2p0, r2p1, r3p0, r3p1 and is still open.
The workaround sets IMP_CLUSTERACTLR_EL1[16:15] bits to 0b11 to disable
clock gating of the SCLK domain. This will increase the idle power
consumption.
This patch applies the fix for Cortex-X2/A510/A710 and Neoverse N2.
SDEN can be found here:
https://developer.arm.com/documentation/SDEN1781796/latest
Signed-off-by: Bipin Ravi <bipin.ravi@arm.com>
Change-Id: I54d948b23e8e01aaf1898ed9fe4e2255dd209318
Signed-off-by: Bipin Ravi <bipin.ravi@arm.com>
diff --git a/lib/cpus/aarch64/dsu_helpers.S b/lib/cpus/aarch64/dsu_helpers.S
index da052d5..419b6ea 100644
--- a/lib/cpus/aarch64/dsu_helpers.S
+++ b/lib/cpus/aarch64/dsu_helpers.S
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2019-2020, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2019-2022, Arm Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
@@ -139,3 +139,57 @@
1:
ret x17
endfunc errata_dsu_936184_wa
+
+ /* -----------------------------------------------------------------------
+ * DSU erratum 2313941 check function
+ * Checks the DSU variant, revision and configuration to determine if
+ * the erratum applies. Erratum applies on all configurations of the
+ * DSU and if revision-variant is r0p0, r1p0, r2p0, r2p1, r3p0, r3p1.
+ *
+ * The erratum is still open.
+ *
+ * This function is called from both assembly and C environment. So it
+ * follows AAPCS.
+ *
+ * Clobbers: x0-x3
+ * -----------------------------------------------------------------------
+ */
+ .globl check_errata_dsu_2313941
+ .globl errata_dsu_2313941_wa
+
+func check_errata_dsu_2313941
+ mov x2, #ERRATA_APPLIES
+ mov x3, #ERRATA_NOT_APPLIES
+
+ /* Check if DSU version is less than or equal to r3p1 */
+ mrs x1, CLUSTERIDR_EL1
+
+ /* DSU variant and revision bitfields in CLUSTERIDR are adjacent */
+ ubfx x0, x1, #CLUSTERIDR_REV_SHIFT,\
+ #(CLUSTERIDR_REV_BITS + CLUSTERIDR_VAR_BITS)
+ mov x1, #(0x31 << CLUSTERIDR_REV_SHIFT)
+ cmp x0, x1
+ csel x0, x2, x3, LS
+ ret
+endfunc check_errata_dsu_2313941
+
+ /* --------------------------------------------------
+ * Errata Workaround for DSU erratum #2313941.
+ *
+ * Can clobber only: x0-x17
+ * --------------------------------------------------
+ */
+func errata_dsu_2313941_wa
+ mov x17, x30
+ bl check_errata_dsu_2313941
+ cbz x0, 1f
+
+ /* If erratum applies, disable high-level clock gating */
+ mrs x0, CLUSTERACTLR_EL1
+ orr x0, x0, #CLUSTERACTLR_EL1_DISABLE_SCLK_GATING
+ msr CLUSTERACTLR_EL1, x0
+ isb
+1:
+ ret x17
+endfunc errata_dsu_2313941_wa
+