errata: workaround for Cortex-A710 erratum 2055002

Cortex-A710 erratum 2055002 is a Cat B erratum that applies to
revisions r1p0 & r2p0 and is still open. The workaround is to
set CPUACTLR_EL1[46] to force L2 tag ECC inline correction mode.
This workaround works on revision r1p0 & r2p0.

SDEN can be found here:
https://developer.arm.com/documentation/SDEN1775101/latest

Signed-off-by: Bipin Ravi <bipin.ravi@arm.com>
Change-Id: I67be1dce53c4651167d8cee33c116e73b9dafe81

docs/design/cpu-specific-build-macros.rst

@@ -378,6 +378,10 @@ For Cortex-A710, the following errata build flags are defined :
    Cortex-A710 CPU. This needs to be enabled only for revisions r0p0, r1p0 and
    r2p0 of the CPU. It is still open.
 
+-  ``ERRATA_A710_2055002``: This applies errata 2055002 workaround to
+   Cortex-A710 CPU. This needs to be enabled for revisions r1p0, r2p0 of the CPU
+   and is still open.
+
 For Neoverse N2, the following errata build flags are defined :
 
 -  ``ERRATA_N2_2067956``: This applies errata 2067956 workaround to Neoverse-N2

include/lib/cpus/aarch64/cortex_a710.h

@@ -20,4 +20,10 @@
 #define CORTEX_A710_CPUPWRCTLR_EL1				S3_0_C15_C2_7
 #define CORTEX_A710_CPUPWRCTLR_EL1_CORE_PWRDN_BIT		U(1)
 
+/*******************************************************************************
+ * CPU Auxiliary Control register specific definitions.
+ ******************************************************************************/
+#define CORTEX_A710_CPUACTLR_EL1 				S3_0_C15_C1_0
+#define CORTEX_A710_CPUACTLR_EL1_BIT_46 			(ULL(1) << 46)
+
 #endif /* CORTEX_A710_H */

lib/cpus/aarch64/cortex_a710.S

@@ -107,6 +107,32 @@ func check_errata_2081180
 	b	cpu_rev_var_ls
 endfunc check_errata_2081180
 
+/* ---------------------------------------------------------------------
+ * Errata Workaround for Cortex-A710 Erratum 2055002.
+ * This applies to revision r1p0, r2p0 of Cortex-A710 and is still open.
+ * Inputs:
+ * x0: variant[4:7] and revision[0:3] of current cpu.
+ * Shall clobber: x0-x17
+ * ---------------------------------------------------------------------
+ */
+func errata_a710_2055002_wa
+	/* Compare x0 against revision r2p0 */
+	mov	x17, x30
+	bl	check_errata_2055002
+	cbz	x0, 1f
+	mrs	x1, CORTEX_A710_CPUACTLR_EL1
+	orr	x1, x1, CORTEX_A710_CPUACTLR_EL1_BIT_46
+	msr	CORTEX_A710_CPUACTLR_EL1, x1
+1:
+	ret	x17
+endfunc errata_a710_2055002_wa
+
+func check_errata_2055002
+	/* Applies to r1p0, r2p0 */
+	mov	x1, #0x20
+	b	cpu_rev_var_ls
+endfunc check_errata_2055002
+
 	/* ----------------------------------------------------
 	 * HW will do the cache maintenance while powering down
 	 * ----------------------------------------------------
@@ -123,10 +149,10 @@ func cortex_a710_core_pwr_dwn
 	ret
 endfunc cortex_a710_core_pwr_dwn
 
-	/*
-	 * Errata printing function for Cortex A710. Must follow AAPCS.
-	 */
 #if REPORT_ERRATA
+	/*
+	 * Errata printing function for Cortex-A710. Must follow AAPCS.
+	 */
 func cortex_a710_errata_report
 	stp	x8, x30, [sp, #-16]!
 
@@ -139,6 +165,7 @@ func cortex_a710_errata_report
 	 */
 	report_errata ERRATA_A710_1987031, cortex_a710, 1987031
 	report_errata ERRATA_A710_2081180, cortex_a710, 2081180
+	report_errata ERRATA_A710_2055002, cortex_a710, 2055002
 
 	ldp	x8, x30, [sp], #16
 	ret
@@ -164,6 +191,11 @@ func cortex_a710_reset_func
 	bl	errata_a710_2081180_wa
 #endif
 
+#if ERRATA_A710_2055002
+	mov	x0, x18
+	bl	errata_a710_2055002_wa
+#endif
+
 	isb
 	ret	x19
 endfunc cortex_a710_reset_func

lib/cpus/cpu-ops.mk

@@ -429,6 +429,10 @@ ERRATA_N2_2067956	?=0
 # to revision r0p0 of the Neoverse N2 cpu and is still open.
 ERRATA_N2_2025414	?=0
 
+# Flag to apply erratum 2055002 workaround during reset. This erratum applies
+# to revision r1p0, r2p0 of the Cortex-A710 cpu and is still open.
+ERRATA_A710_2055002	?=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
@@ -790,6 +794,10 @@ $(eval $(call add_define,ERRATA_N2_2067956))
 $(eval $(call assert_boolean,ERRATA_N2_2025414))
 $(eval $(call add_define,ERRATA_N2_2025414))
 
+# Process ERRATA_A710_2055002 flag
+$(eval $(call assert_boolean,ERRATA_A710_2055002))
+$(eval $(call add_define,ERRATA_A710_2055002))
+
 # Process ERRATA_DSU_798953 flag
 $(eval $(call assert_boolean,ERRATA_DSU_798953))
 $(eval $(call add_define,ERRATA_DSU_798953))