Cortex-A55: Implement workaround for erratum 778703

Change-Id: I094e5cb2c44618e7a4116af5fbb6b18078a79951
Signed-off-by: Ambroise Vincent <ambroise.vincent@arm.com>

docs/cpu-specific-build-macros.rst

@@ -102,6 +102,9 @@ For Cortex-A55, the following errata build flags are defined :
 -  ``ERRATA_A55_768277``: This applies errata 768277 workaround to Cortex-A55
    CPU. This needs to be enabled only for revision r0p0 of the CPU.
 
+-  ``ERRATA_A55_778703``: This applies errata 778703 workaround to Cortex-A55
+   CPU. This needs to be enabled only for revision r0p0 of the CPU.
+
 For Cortex-A57, the following errata build flags are defined :
 
 -  ``ERRATA_A57_806969``: This applies errata 806969 workaround to Cortex-A57

include/lib/cpus/aarch64/cortex_a55.h

@@ -18,13 +18,23 @@
 #define CORTEX_A55_CPUPWRCTLR_EL1	S3_0_C15_C2_7
 #define CORTEX_A55_CPUECTLR_EL1		S3_0_C15_C1_4
 
+#define CORTEX_A55_CPUECTLR_EL1_L1WSCTL	(ULL(3) << 25)
+
 /*******************************************************************************
  * CPU Auxiliary Control register specific definitions.
  ******************************************************************************/
 #define CORTEX_A55_CPUACTLR_EL1				S3_0_C15_C1_0
 
+#define CORTEX_A55_CPUACTLR_EL1_DISABLE_WRITE_STREAMING	(ULL(1) << 24)
 #define CORTEX_A55_CPUACTLR_EL1_DISABLE_DUAL_ISSUE	(ULL(1) << 31)
 
+/*******************************************************************************
+ * CPU Identification register specific definitions.
+ ******************************************************************************/
+#define CORTEX_A55_CLIDR_EL1				S3_1_C0_C0_1
+
+#define CORTEX_A55_CLIDR_EL1_CTYPE3			(ULL(7) << 6)
+
 /* Definitions of register field mask in CORTEX_A55_CPUPWRCTLR_EL1 */
 #define CORTEX_A55_CORE_PWRDN_EN_MASK	U(0x1)
 

lib/cpus/aarch64/cortex_a55.S

@@ -39,6 +39,49 @@ func check_errata_768277
 	b	cpu_rev_var_ls
 endfunc check_errata_768277
 
+	/* ------------------------------------------------------------------
+	 * Errata Workaround for Cortex A55 Errata #778703.
+	 * This applies only to revision r0p0 of Cortex A55 where L2 cache is
+	 * not configured.
+	 * Inputs:
+	 * x0: variant[4:7] and revision[0:3] of current cpu.
+	 * Shall clobber: x0-x17
+	 * ------------------------------------------------------------------
+	 */
+func errata_a55_778703_wa
+	/*
+	 * Compare x0 against revision r0p0 and check that no private L2 cache
+	 * is configured
+	 */
+	mov	x17, x30
+	bl	check_errata_778703
+	cbz	x0, 1f
+	mrs	x1, CORTEX_A55_CPUECTLR_EL1
+	orr	x1, x1, #CORTEX_A55_CPUECTLR_EL1_L1WSCTL
+	msr	CORTEX_A55_CPUECTLR_EL1, x1
+	mrs	x1, CORTEX_A55_CPUACTLR_EL1
+	orr	x1, x1, #CORTEX_A55_CPUACTLR_EL1_DISABLE_WRITE_STREAMING
+	msr	CORTEX_A55_CPUACTLR_EL1, x1
+	isb
+1:
+	ret	x17
+endfunc errata_a55_778703_wa
+
+func check_errata_778703
+	mov	x16, x30
+	mov	x1, #0x00
+	bl	cpu_rev_var_ls
+	/*
+	 * Check that no private L2 cache is configured
+	 */
+	mrs	x1, CORTEX_A55_CLIDR_EL1
+	and	x1, x1, CORTEX_A55_CLIDR_EL1_CTYPE3
+	cmp	x1, #0
+	mov	x2, #ERRATA_NOT_APPLIES
+	csel	x0, x0, x2, eq
+	ret	x16
+endfunc check_errata_778703
+
 func cortex_a55_reset_func
 	mov	x19, x30
 
@@ -54,6 +97,11 @@ func cortex_a55_reset_func
 	bl	errata_a55_768277_wa
 #endif
 
+#if ERRATA_A55_778703
+	mov	x0, x18
+	bl	errata_a55_778703_wa
+#endif
+
 	ret	x19
 endfunc cortex_a55_reset_func
 
@@ -88,6 +136,7 @@ func cortex_a55_errata_report
 	 */
 	report_errata ERRATA_DSU_936184, cortex_a55, dsu_936184
 	report_errata ERRATA_A55_768277, cortex_a55, 768277
+	report_errata ERRATA_A55_778703, cortex_a55, 778703
 
 	ldp	x8, x30, [sp], #16
 	ret

lib/cpus/cpu-ops.mk

@@ -83,6 +83,10 @@ ERRATA_A53_855873	?=0
 # only to revision r0p0 of the Cortex A55 cpu.
 ERRATA_A55_768277	?=0
 
+# Flag to apply erratum 778703 workaround during reset. This erratum applies
+# only to revision r0p0 of the Cortex A55 cpu.
+ERRATA_A55_778703	?=0
+
 # Flag to apply erratum 806969 workaround during reset. This erratum applies
 # only to revision r0p0 of the Cortex A57 cpu.
 ERRATA_A57_806969	?=0
@@ -156,6 +160,10 @@ $(eval $(call add_define,ERRATA_A53_855873))
 $(eval $(call assert_boolean,ERRATA_A55_768277))
 $(eval $(call add_define,ERRATA_A55_768277))
 
+# Process ERRATA_A55_778703 flag
+$(eval $(call assert_boolean,ERRATA_A55_778703))
+$(eval $(call add_define,ERRATA_A55_778703))
+
 # Process ERRATA_A57_806969 flag
 $(eval $(call assert_boolean,ERRATA_A57_806969))
 $(eval $(call add_define,ERRATA_A57_806969))