fix(cpus): workaround for Cortex-A78C erratum 2779484

Cortex-A78C erratum 2779484 is a Cat B erratum that applies to
revisions r0p1 and r0p2 and is still open.

The workaround is to set the CPUACTLR3_EL1[47] bit to 1. Setting this
bit might have a small impact on power and negligible impact on
performance.

SDEN documentation:
https://developer.arm.com/documentation/SDEN2004089/latest

Signed-off-by: Bipin Ravi <bipin.ravi@arm.com>
Change-Id: I9a8c16a845c3ba6eb2f17a5119aa6ca09a0d27ed

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

@@ -369,6 +369,10 @@ For Cortex-A78C, the following errata build flags are defined :
   Cortex-A78C CPU. This needs to be enabled for revisions r0p0, r0p1 and r0p2.
   This erratum is still open.
 
+- ``ERRATA_A78C_2779484`` : This applies errata 2779484 workaround to
+  Cortex-A78C CPU. This needs to be enabled for revisions r0p1 and r0p2.
+  This erratum is still open.
+
 For Cortex-X1 CPU, the following errata build flags are defined:
 
 - ``ERRATA_X1_1821534`` : This applies errata 1821534 workaround to Cortex-X1

include/lib/cpus/aarch64/cortex_a78c.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021-2022, Arm Limited. All rights reserved.
+ * Copyright (c) 2021-2023, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -33,6 +33,11 @@
 #define CORTEX_A78C_CPUPWRCTLR_EL1			S3_0_C15_C2_7
 #define CORTEX_A78C_CPUPWRCTLR_EL1_CORE_PWRDN_EN_BIT	U(1)
 
+/*******************************************************************************
+ * CPU Auxiliary Control register 3 specific definitions.
+ ******************************************************************************/
+#define CORTEX_A78C_ACTLR3_EL1				S3_0_C15_C1_2
+
 /*******************************************************************************
  * CPU Implementation Specific Selected Instruction registers
  ******************************************************************************/

lib/cpus/aarch64/cortex_a78c.S

@@ -177,6 +177,36 @@ func check_errata_2772121
 	b	cpu_rev_var_ls
 endfunc check_errata_2772121
 
+/* --------------------------------------------------
+ * Errata Workaround for Cortex A78C Errata 2779484.
+ * This applies to revisions r0p1 and r0p2.
+ * It is still open.
+ * x0: variant[4:7] and revision[0:3] of current cpu.
+ * Shall clobber: x0-x1, x17
+ * --------------------------------------------------
+ */
+func errata_a78c_2779484_wa
+	/* Check revision. */
+	mov	x17, x30
+	bl	check_errata_2779484
+	cbz	x0, 1f
+
+	/* Apply the workaround */
+	mrs	x1, CORTEX_A78C_ACTLR3_EL1
+	orr	x1, x1, #BIT(47)
+	msr	CORTEX_A78C_ACTLR3_EL1, x1
+
+1:
+	ret	x17
+endfunc errata_a78c_2779484_wa
+
+func check_errata_2779484
+	/* Applies to r0p1 and r0p2*/
+	mov	x1, #0x01
+	mov	x2, #0x02
+	b	cpu_rev_var_range
+endfunc check_errata_2779484
+
 func check_errata_cve_2022_23960
 #if WORKAROUND_CVE_2022_23960
 	mov	x0, #ERRATA_APPLIES
@@ -215,6 +245,11 @@ func cortex_a78c_reset_func
 	bl	errata_a78c_2395411_wa
 #endif
 
+#if ERRATA_A78C_2779484
+	mov	x0, x18
+	bl	errata_a78c_2779484_wa
+#endif
+
 #if IMAGE_BL31 && WORKAROUND_CVE_2022_23960
 	/*
 	 * The Cortex-A78c generic vectors are overridden to apply errata
@@ -269,6 +304,7 @@ func cortex_a78c_errata_report
 	report_errata ERRATA_A78C_2376749, cortex_a78c, 2376749
 	report_errata ERRATA_A78C_2395411, cortex_a78c, 2395411
 	report_errata ERRATA_A78C_2772121, cortex_a78c, 2772121
+	report_errata ERRATA_A78C_2779484, cortex_a78c, 2779484
 	report_errata WORKAROUND_CVE_2022_23960, cortex_a78c, cve_2022_23960
 
 	ldp	x8, x30, [sp], #16

lib/cpus/cpu-ops.mk

@@ -407,6 +407,10 @@ ERRATA_A78C_2395411 	?=0
 # applies to revisions r0p0, r0p1 and r0p2 of the A78C cpu. It is still open.
 ERRATA_A78C_2772121 	?=0
 
+# Flag to apply erratum 2779484 workaround during reset. This erratum
+# applies to revisions r0p1 and r0p2 of the A78C cpu. It is still open.
+ERRATA_A78C_2779484 	?=0
+
 # Flag to apply erratum 1821534 workaround during reset. This erratum applies
 # to revisions r0p0 - r1p0 of the X1 cpu and fixed in r1p1.
 ERRATA_X1_1821534	?=0
@@ -1097,6 +1101,10 @@ $(eval $(call add_define,ERRATA_A78C_2395411))
 $(eval $(call assert_boolean,ERRATA_A78C_2772121))
 $(eval $(call add_define,ERRATA_A78C_2772121))
 
+# Process ERRATA_A78C_2779484 flag
+$(eval $(call assert_boolean,ERRATA_A78C_2779484))
+$(eval $(call add_define,ERRATA_A78C_2779484))
+
 # Process ERRATA_X1_1821534 flag
 $(eval $(call assert_boolean,ERRATA_X1_1821534))
 $(eval $(call add_define,ERRATA_X1_1821534))