ARM: 7541/1: Add ARM ERRATA 775420 workaround

arm: Add ARM ERRATA 775420 workaround

Workaround for the 775420 Cortex-A9 (r2p2, r2p6,r2p8,r2p10,r3p0) erratum.
In case a date cache maintenance operation aborts with MMU exception, it
might cause the processor to deadlock. This workaround puts DSB before
executing ISB if an abort may occur on cache maintenance.

Based on work by Kouei Abe and feedback from Catalin Marinas.

Signed-off-by: Kouei Abe <kouei.abe.cp@rms.renesas.com>
[ horms@verge.net.au: Changed to implementation
  suggested by catalin.marinas@arm.com ]
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 13 insertions, 0 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 2f88d8d97701..48c19d44be9a 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1413,6 +1413,16 @@ config PL310_ERRATA_769419
           on systems with an outer cache, the store buffer is drained
           explicitly.
 
+config ARM_ERRATA_775420
+       bool "ARM errata: A data cache maintenance operation which aborts, might lead to deadlock"
+       depends on CPU_V7
+       help
+         This option enables the workaround for the 775420 Cortex-A9 (r2p2,
+         r2p6,r2p8,r2p10,r3p0) erratum. In case a date cache maintenance
+         operation aborts with MMU exception, it might cause the processor
+         to deadlock. This workaround puts DSB before executing ISB if
+         an abort may occur on cache maintenance.
+
 endmenu
 
 source "arch/arm/common/Kconfig"
diff --git a/arch/arm/mm/cache-v7.S b/arch/arm/mm/cache-v7.S
index 39e3fb3db801..3b172275262e 100644
--- a/arch/arm/mm/cache-v7.S
+++ b/arch/arm/mm/cache-v7.S
@@ -211,6 +211,9 @@ ENTRY(v7_coherent_user_range)
  * isn't mapped, fail with -EFAULT.
  */
 9001:
+#ifdef CONFIG_ARM_ERRATA_775420
+        dsb
+#endif
         mov     r0, #-EFAULT
         mov     pc, lr
  UNWIND(.fnend          )