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authorRussell King <rmk+kernel@arm.linux.org.uk>2011-02-04 10:36:39 +0000
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-02-11 12:29:18 +0000
commit292ec42af7c6361435fe9df50cd59ec76f6741c6 (patch)
tree376c6bdc9f615988c19f9597020a8cde99005543 /arch/arm/kernel/smp_scu.c
parentafe8a887550f7cc24eb16449670b93f6b43c32d8 (diff)
downloadlinux-292ec42af7c6361435fe9df50cd59ec76f6741c6.tar.bz2
ARM: pm: add function to set WFI low-power mode for SMP CPUs
Add a function to set the SCU low-power mode for SMP CPUs. This centralizes this functionality rather than having to expose the SCU register definitions to each platform. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel/smp_scu.c')
-rw-r--r--arch/arm/kernel/smp_scu.c23
1 files changed, 23 insertions, 0 deletions
diff --git a/arch/arm/kernel/smp_scu.c b/arch/arm/kernel/smp_scu.c
index 9ab4149bd983..a1e757c3439b 100644
--- a/arch/arm/kernel/smp_scu.c
+++ b/arch/arm/kernel/smp_scu.c
@@ -50,3 +50,26 @@ void __init scu_enable(void __iomem *scu_base)
*/
flush_cache_all();
}
+
+/*
+ * Set the executing CPUs power mode as defined. This will be in
+ * preparation for it executing a WFI instruction.
+ *
+ * This function must be called with preemption disabled, and as it
+ * has the side effect of disabling coherency, caches must have been
+ * flushed. Interrupts must also have been disabled.
+ */
+int scu_power_mode(void __iomem *scu_base, unsigned int mode)
+{
+ unsigned int val;
+ int cpu = smp_processor_id();
+
+ if (mode > 3 || mode == 1 || cpu > 3)
+ return -EINVAL;
+
+ val = __raw_readb(scu_base + SCU_CPU_STATUS + cpu) & ~0x03;
+ val |= mode;
+ __raw_writeb(val, scu_base + SCU_CPU_STATUS + cpu);
+
+ return 0;
+}