[PATCH v5 06/14] ARM: mvebu: Low level function to disable HW coherency support

Gregory CLEMENT
2014-03-25T22:48:55Z

When going to deep idle we need to disable the SoC snooping (aka
hardware coherency support). Playing with the coherency fabric
requires to use assembly code to be sure that the compiler doesn't
reorder the instructions nor do wrong optimization.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
---
arch/arm/mach-mvebu/coherency_ll.S | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

diff --git a/arch/arm/mach-mvebu/coherency_ll.S b/arch/arm/mach-mvebu/coherency_ll.S
index c7179a03891d..6e1b31fb1a94 100644
--- a/arch/arm/mach-mvebu/coherency_ll.S
+++ b/arch/arm/mach-mvebu/coherency_ll.S
@@ -102,6 +102,26 @@ ENTRY(ll_enable_coherency)
mov pc, lr
ENDPROC(ll_enable_coherency)

+ENTRY(ll_disable_coherency)
+ /*
+ * r0 being untouched in ll_get_coherency_base and
+ * ll_get_cpuid, we can use it to save lr modifing it with the
+ * following bl
+ */
+ mov r0, lr
+ bl ll_get_coherency_base
+ bl ll_get_cpuid
+ mov lr, r0
+ add r0, r1, #ARMADA_XP_CFB_CTL_REG_OFFSET
+1:
+ ldrex r2, [r0]
+ bic r2, r2, r3
+ strex r1, r2, [r0]
+ cmp r1, #0
+ bne 1b
+ dsb
+ mov pc, lr
+ENDPROC(ll_disable_coherency)

.align 2
3:
--
1.8.1.2