[U-Boot] [PATCH v2] armv8: errata: Implement workaround for Cortex-A53 Erratum 855873

[Alison Wang]

855873: An eviction might overtake a cache clean operation
Workaround: The erratum can be avoided by upgrading cache clean by
address operations to cache clean and invalidate operations. For
Cortex-A53 r0p3 and later release, this can be achieved by setting
CPUACTLR.ENDCCASCI to 1.

This patch is to implement the workaround for this erratum.

Signed-off-by: Alison Wang <alison.wang at nxp.com>
---
Changes in v2:
- Check the revision of Cortex-A53 and apply the erratum to r0p3 and later release.
- Fix the mistake in the commit description.

 arch/arm/Kconfig                          |  3 +++
 arch/arm/cpu/armv8/fsl-layerscape/Kconfig |  2 ++
 arch/arm/cpu/armv8/start.S                | 20 +++++++++++++++++++-
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index d43aaac..4a885a3 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -103,6 +103,9 @@ config ARM_ERRATA_852421
 config ARM_ERRATA_852423
 	bool
 
+config ARM_ERRATA_855873
+	bool
+
 config CPU_ARM720T
 	bool
 	select SYS_CACHE_SHIFT_5
diff --git a/arch/arm/cpu/armv8/fsl-layerscape/Kconfig b/arch/arm/cpu/armv8/fsl-layerscape/Kconfig
index 5825f9b..63658b5 100644
--- a/arch/arm/cpu/armv8/fsl-layerscape/Kconfig
+++ b/arch/arm/cpu/armv8/fsl-layerscape/Kconfig
@@ -1,6 +1,7 @@
 config ARCH_LS1012A
 	bool
 	select ARMV8_SET_SMPEN
+	select ARM_ERRATA_855873
 	select FSL_LSCH2
 	select SYS_FSL_DDR_BE
 	select SYS_FSL_MMDC
@@ -11,6 +12,7 @@ config ARCH_LS1012A
 config ARCH_LS1043A
 	bool
 	select ARMV8_SET_SMPEN
+	select ARM_ERRATA_855873
 	select FSL_LSCH2
 	select SYS_FSL_DDR
 	select SYS_FSL_DDR_BE
diff --git a/arch/arm/cpu/armv8/start.S b/arch/arm/cpu/armv8/start.S
index 5c500be..6ca054b 100644
--- a/arch/arm/cpu/armv8/start.S
+++ b/arch/arm/cpu/armv8/start.S
@@ -170,7 +170,10 @@ reset_sctrl:
 WEAK(apply_core_errata)
 
 	mov	x29, lr			/* Save LR */
-	/* For now, we support Cortex-A57 specific errata only */
+	/* For now, we support Cortex-A53, Cortex-A57 specific errata */
+
+	/* Check if we are running on a Cortex-A53 core */
+	branch_if_a53_core x0, apply_a53_core_errata
 
 	/* Check if we are running on a Cortex-A57 core */
 	branch_if_a57_core x0, apply_a57_core_errata
@@ -178,6 +181,21 @@ WEAK(apply_core_errata)
 	mov	lr, x29			/* Restore LR */
 	ret
 
+apply_a53_core_errata:
+
+#ifdef CONFIG_ARM_ERRATA_855873
+	mrs	x0, midr_el1
+	and	x0, x0, #0xf
+	cmp	x0, #3
+	b.lt	0b
+
+	mrs	x0, S3_1_c15_c2_0	/* cpuactlr_el1 */
+	/* Enable data cache clean as data cache clean/invalidate */
+	orr	x0, x0, #1 << 44
+	msr	S3_1_c15_c2_0, x0	/* cpuactlr_el1 */
+#endif
+	b 0b
+
 apply_a57_core_errata:
 
 #ifdef CONFIG_ARM_ERRATA_828024
-- 
2.1.0.27.g96db324