errata: workaround for Cortex A77 errata 1791578

Cortex A77 erratum 1791578 is a Cat B erratum present in r0p0, r1p0,
and r1p1 of the A77 processor core, it is still open.

SDEN can be found here:
https://documentation-service.arm.com/static/60a63a3c982fc7708ac1c8b1

Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: Ib4b963144f880002de308def12744b982d3df868

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

@@ -263,6 +263,9 @@ For Cortex-A77, the following errata build flags are defined :
 -  ``ERRATA_A77_1946167``: This applies errata 1946167 workaround to Cortex-A77
    CPU. This needs to be enabled only for revision <= r1p1 of the CPU.
 
+-  ``ERRATA_A77_1791578``: This applies errata 1791578 workaround to Cortex-A77
+   CPU. This needs to be enabled for r0p0, r1p0, and r1p1, it is still open.
+
 For Cortex-A78, the following errata build flags are defined :
 
 -  ``ERRATA_A78_1688305``: This applies errata 1688305 workaround to Cortex-A78

include/lib/cpus/aarch64/cortex_a77.h

 /*
- * Copyright (c) 2018-2020, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2021, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -24,6 +24,12 @@
 #define CORTEX_A77_CPUPWRCTLR_EL1			S3_0_C15_C2_7
 #define CORTEX_A77_CPUPWRCTLR_EL1_CORE_PWRDN_BIT	(U(1) << 0)
 
+/*******************************************************************************
+ * CPU Auxiliary Control register specific definitions.
+ ******************************************************************************/
+#define CORTEX_A77_ACTLR2_EL1				S3_0_C15_C1_1
+#define CORTEX_A77_ACTLR2_EL1_BIT_2			(ULL(1) << 2)
+
 #define CORTEX_A77_CPUPSELR_EL3				S3_6_C15_C8_0
 #define CORTEX_A77_CPUPCR_EL3				S3_6_C15_C8_1
 #define CORTEX_A77_CPUPOR_EL3				S3_6_C15_C8_2

lib/cpus/aarch64/cortex_a77.S

@@ -166,6 +166,34 @@ func check_errata_1946167
 	b	cpu_rev_var_ls
 endfunc check_errata_1946167
 
+	/* --------------------------------------------------
+	 * Errata Workaround for Cortex A77 Errata #1791578.
+	 * This applies to revisions r0p0, r1p0, and r1p1 and is still open.
+	 * x0: variant[4:7] and revision[0:3] of current cpu.
+	 * Shall clobber: x0-x17
+	 * --------------------------------------------------
+	 */
+func errata_a77_1791578_wa
+	/* Check workaround compatibility. */
+	mov	x17, x30
+	bl	check_errata_1791578
+	cbz	x0, 1f
+
+	/* Set bit 2 in ACTLR2_EL1 */
+	mrs     x1, CORTEX_A77_ACTLR2_EL1
+	orr	x1, x1, #CORTEX_A77_ACTLR2_EL1_BIT_2
+	msr     CORTEX_A77_ACTLR2_EL1, x1
+	isb
+1:
+	ret	x17
+endfunc errata_a77_1791578_wa
+
+func check_errata_1791578
+	/* Applies to r0p0, r1p0, and r1p1 right now */
+	mov	x1, #0x11
+	b	cpu_rev_var_ls
+endfunc check_errata_1791578
+
 	/* -------------------------------------------------
 	 * The CPU Ops reset function for Cortex-A77.
 	 * Shall clobber: x0-x19
@@ -191,6 +219,11 @@ func cortex_a77_reset_func
 	bl	errata_a77_1946167_wa
 #endif
 
+#if ERRATA_A77_1791578
+	mov	x0, x18
+	bl	errata_a77_1791578_wa
+#endif
+
 	ret	x19
 endfunc cortex_a77_reset_func
 
@@ -227,6 +260,7 @@ func cortex_a77_errata_report
 	report_errata ERRATA_A77_1508412, cortex_a77, 1508412
 	report_errata ERRATA_A77_1925769, cortex_a77, 1925769
 	report_errata ERRATA_A77_1946167, cortex_a77, 1946167
+	report_errata ERRATA_A77_1791578, cortex_a77, 1791578
 
 	ldp	x8, x30, [sp], #16
 	ret

lib/cpus/cpu-ops.mk

@@ -294,6 +294,10 @@ ERRATA_A77_1925769	?=0
 # only to revision <= r1p1 of the Cortex A77 cpu.
 ERRATA_A77_1946167	?=0
 
+# Flag to apply erratum 1791578 workaround during reset. This erratum applies
+# to revisions r0p0, r1p0, and r1p1, it is still open.
+ERRATA_A77_1791578	?=0
+
 # Flag to apply erratum 1688305 workaround during reset. This erratum applies
 # to revisions r0p0 - r1p0 of the A78 cpu.
 ERRATA_A78_1688305	?=0
@@ -593,6 +597,10 @@ $(eval $(call add_define,ERRATA_A77_1925769))
 $(eval $(call assert_boolean,ERRATA_A77_1946167))
 $(eval $(call add_define,ERRATA_A77_1946167))
 
+# Process ERRATA_A77_1791578 flag
+$(eval $(call assert_boolean,ERRATA_A77_1791578))
+$(eval $(call add_define,ERRATA_A77_1791578))
+
 # Process ERRATA_A78_1688305 flag
 $(eval $(call assert_boolean,ERRATA_A78_1688305))
 $(eval $(call add_define,ERRATA_A78_1688305))