From c716483c3db10b31bf9bf43c5f45f2c3117ca13a Mon Sep 17 00:00:00 2001
From: Shawn Guo <shawn.guo@linaro.org>
Date: Thu, 31 Jul 2014 02:07:37 +0100
Subject: 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>
---
 arch/arm/kernel/smp_scu.c | 7 +++++++
 1 file changed, 7 insertions(+)

(limited to 'arch')

diff --git a/arch/arm/kernel/smp_scu.c b/arch/arm/kernel/smp_scu.c
index c947508f84e6..72f9241ad5db 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 @@ void scu_enable(void __iomem *scu_base)
 		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);
 
 	/*
-- 
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