ARM: 8122/1: smp_scu: enable SCU standby support
With SCU standby enabled, SCU CLK will be turned off when all processors
are in WFI mode. And the clock will be turned on when any processor
leaves WFI mode.
This behavior should be preferable in terms of power efficiency of
system idle. So let's set the SCU standby bit to enable the support in
function scu_enable().
Cortex-A9 earlier than r2p0 has no standby bit in SCU, so we need to
skip setting the bit for those.
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>
Acked-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/smp_scu.c b/arch/arm/kernel/smp_scu.c
index c947508..72f9241 100644
--- a/arch/arm/kernel/smp_scu.c
+++ b/arch/arm/kernel/smp_scu.c
@@ -18,6 +18,7 @@
#define SCU_CTRL 0x00
#define SCU_ENABLE (1 << 0)
+#define SCU_STANDBY_ENABLE (1 << 5)
#define SCU_CONFIG 0x04
#define SCU_CPU_STATUS 0x08
#define SCU_INVALIDATE 0x0c
@@ -55,6 +56,12 @@
return;
scu_ctrl |= SCU_ENABLE;
+
+ /* Cortex-A9 earlier than r2p0 has no standby bit in SCU */
+ if ((read_cpuid_id() & 0xff0ffff0) == 0x410fc090 &&
+ (read_cpuid_id() & 0x00f0000f) >= 0x00200000)
+ scu_ctrl |= SCU_STANDBY_ENABLE;
+
writel_relaxed(scu_ctrl, scu_base + SCU_CTRL);
/*
