[U-Boot] [PATCH v4 03/10] Exynos542x: Add workaround for ARM errata 798870

[Akshay Saraswat]

This patch adds workaround for ARM errata 798870 which says
"If back-to-back speculative cache line fills (fill A and fill B) are
issued from the L1 data cache of a CPU to the L2 cache, the second
request (fill B) is then cancelled, and the second request would have
detected a hazard against a recent write or eviction (write B) to the
same cache line as fill B then the L2 logic might deadlock."

Signed-off-by: Kimoon Kim <kimoon.kim at samsung.com>
Signed-off-by: Akshay Saraswat <akshay.s at samsung.com>
Reviewed-by: Simon Glass <sjg at chromium.org>
Tested-by: Simon Glass <sjg at chromium.org>
---
Changes since v3:
	- Added errata number in comment.
	- Moved changes to arm generic armv7.h

Changes since v2:
	- No change.

Changes since v1:
	- Added Reviewed-by & Tested-by.
	- Added space before */ on line # 40.

 arch/arm/include/asm/armv7.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/arch/arm/include/asm/armv7.h b/arch/arm/include/asm/armv7.h
index a13da23..a2040b7 100644
--- a/arch/arm/include/asm/armv7.h
+++ b/arch/arm/include/asm/armv7.h
@@ -69,6 +69,22 @@
 #define CP15DSB	asm volatile ("mcr     p15, 0, %0, c7, c10, 4" : : "r" (0))
 #define CP15DMB	asm volatile ("mcr     p15, 0, %0, c7, c10, 5" : : "r" (0))
 
+/*
+ * Workaround for ARM errata # 798870
+ * Set L2ACTLR[7] to reissue any memory transaction in the L2 that has been
+ * stalled for 1024 cycles to verify that its hazard condition still exists.
+ */
+static inline void v7_enable_l2_hazard_detect(void)
+{
+	uint32_t val;
+
+	/* L2ACTLR[7]: Enable hazard detect timeout */
+	asm volatile ("mrc     p15, 1, %0, c15, c0, 0\n\t" : "=r"(val));
+	val |= (1 << 7);
+	asm volatile ("mcr     p15, 1, %0, c15, c0, 0\n\t" : : "r"(val));
+}
+
+void v7_en_l2_hazard_detect(void);
 void v7_outer_cache_enable(void);
 void v7_outer_cache_disable(void);
 void v7_outer_cache_flush_all(void);
-- 
1.9.1