Cortex-A35: Implement workaround for errata 855472

Under specific conditions, the processor might issue an eviction and an
L2 cache clean operation to the interconnect in the wrong order. Set
the CPUACTLR.ENDCCASCI bit to 1 to avoid this.

Change-Id: Ide7393adeae04581fa70eb9173b742049fc3e050
Signed-off-by: Louis Mayencourt <louis.mayencourt@arm.com>

docs/cpu-specific-build-macros.rst

@@ -92,6 +92,11 @@ For Cortex-A17, the following errata build flags are defined :
 -  ``ERRATA_A17_852423``: This applies errata 852423 workaround to Cortex-A17
    CPU. This needs to be enabled only for revision <= r1p2 of the CPU.
 
+For Cortex-A35, the following errata build flags are defined :
+
+-  ``ERRATA_A35_855472``: This applies errata 855472 workaround to Cortex-A35
+   CPUs. This needs to be enabled only for revision r0p0 of Cortex-A35.
+
 For Cortex-A53, the following errata build flags are defined :
 
 -  ``ERRATA_A53_819472``: This applies errata 819472 workaround to all

include/lib/cpus/aarch64/cortex_a35.h

@@ -19,4 +19,11 @@
 #define CORTEX_A35_CPUECTLR_EL1			S3_1_C15_C2_1
 #define CORTEX_A35_CPUECTLR_SMPEN_BIT		(ULL(1) << 6)
 
+/*******************************************************************************
+ * CPU Auxiliary Control register specific definitions.
+ ******************************************************************************/
+#define CORTEX_A35_CPUACTLR_EL1			S3_1_C15_C2_0
+
+#define CORTEX_A35_CPUACTLR_EL1_ENDCCASCI	(ULL(1) << 44)
+
 #endif /* CORTEX_A35_H */

lib/cpus/aarch64/cortex_a35.S

 /*
- * Copyright (c) 2016, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -36,12 +36,47 @@ func cortex_a35_disable_smp
 	ret
 endfunc cortex_a35_disable_smp
 
+	 /* ---------------------------------------------------
+	 * Errata Workaround for Cortex A35 Errata #855472.
+	 * This applies to revisions r0p0 of Cortex A35.
+	 * Inputs:
+	 * x0: variant[4:7] and revision[0:3] of current cpu.
+	 * Shall clobber: x0-x17
+	 * ---------------------------------------------------
+	 */
+func errata_a35_855472_wa
+	 /*
+	  * Compare x0 against revision r0p0
+	  */
+	 mov	x17, x30
+	 bl	check_errata_855472
+	 cbz	x0, 1f
+	 mrs	x1, CORTEX_A35_CPUACTLR_EL1
+	 orr	x1, x1, #CORTEX_A35_CPUACTLR_EL1_ENDCCASCI
+	 msr	CORTEX_A35_CPUACTLR_EL1, x1
+	 isb
+1:
+	ret	x17
+endfunc errata_a35_855472_wa
+
+func check_errata_855472
+	mov	x1, #0x00
+	b	cpu_rev_var_ls
+endfunc check_errata_855472
+
 	/* -------------------------------------------------
 	 * The CPU Ops reset function for Cortex-A35.
 	 * Clobbers: x0
 	 * -------------------------------------------------
 	 */
 func cortex_a35_reset_func
+	mov	x19, x30
+	bl	cpu_get_rev_var
+
+#if ERRATA_A35_855472
+	bl	errata_a35_855472_wa
+#endif
+
 	/* ---------------------------------------------
 	 * Enable the SMP bit.
 	 * ---------------------------------------------
@@ -50,7 +85,7 @@ func cortex_a35_reset_func
 	orr	x0, x0, #CORTEX_A35_CPUECTLR_SMPEN_BIT
 	msr	CORTEX_A35_CPUECTLR_EL1, x0
 	isb
-	ret
+	ret	x19
 endfunc cortex_a35_reset_func
 
 func cortex_a35_core_pwr_dwn
@@ -119,6 +154,18 @@ endfunc cortex_a35_cluster_pwr_dwn
  * Errata printing function for Cortex A35. Must follow AAPCS.
  */
 func cortex_a35_errata_report
+	stp	x8, x30, [sp, #-16]!
+
+	bl	cpu_get_rev_var
+	mov	x8, x0
+
+	/*
+	 * Report all errata. The revision-variant information is passed to
+	 * checking functions of each errata.
+	 */
+	report_errata ERRATA_A35_855472, cortex_a35, 855472
+
+	ldp	x8, x30, [sp], #16
 	ret
 endfunc cortex_a35_errata_report
 #endif

lib/cpus/cpu-ops.mk

@@ -72,6 +72,10 @@ ERRATA_A17_852421	?=0
 # only to revision <= r1p2 of the Cortex A17 cpu.
 ERRATA_A17_852423	?=0
 
+# Flag to apply erratum 855472 workaround during reset. This erratum applies
+# only to revision r0p0 of the Cortex A35 cpu.
+ERRATA_A35_855472	?=0
+
 # Flag to apply erratum 819472 workaround during reset. This erratum applies
 # only to revision <= r0p1 of the Cortex A53 cpu.
 ERRATA_A53_819472	?=0
@@ -235,6 +239,10 @@ $(eval $(call add_define,ERRATA_A17_852421))
 $(eval $(call assert_boolean,ERRATA_A17_852423))
 $(eval $(call add_define,ERRATA_A17_852423))
 
+# Process ERRATA_A35_855472 flag
+$(eval $(call assert_boolean,ERRATA_A35_855472))
+$(eval $(call add_define,ERRATA_A35_855472))
+
 # Process ERRATA_A53_819472 flag
 $(eval $(call assert_boolean,ERRATA_A53_819472))
 $(eval $(call add_define,ERRATA_A53_819472))