From 1b7f72fc395d3d2b498fee5ecfb9e46497f55cdd Mon Sep 17 00:00:00 2001
From: Nicolas Pitre <nicolas.pitre@linaro.org>
Date: Tue, 2 Aug 2011 12:52:48 -0400
Subject: ARM: mach-ebsa110: move special idle code out of line
... and hook it to arm_pm_idle.
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
---
arch/arm/mach-ebsa110/core.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
(limited to 'arch/arm/mach-ebsa110/core.c')
diff --git a/arch/arm/mach-ebsa110/core.c b/arch/arm/mach-ebsa110/core.c
index 294aad07f7a0..804c9122b7b3 100644
--- a/arch/arm/mach-ebsa110/core.c
+++ b/arch/arm/mach-ebsa110/core.c
@@ -271,8 +271,33 @@ static struct platform_device *ebsa110_devices[] = {
&am79c961_device,
};
+/*
+ * EBSA110 idling methodology:
+ *
+ * We can not execute the "wait for interrupt" instruction since that
+ * will stop our MCLK signal (which provides the clock for the glue
+ * logic, and therefore the timer interrupt).
+ *
+ * Instead, we spin, polling the IRQ_STAT register for the occurrence
+ * of any interrupt with core clock down to the memory clock.
+ */
+static void ebsa110_idle(void)
+{
+ const char *irq_stat = (char *)0xff000000;
+
+ /* disable clock switching */
+ asm volatile ("mcr p15, 0, ip, c15, c2, 2" : : : "cc");
+
+ /* wait for an interrupt to occur */
+ while (!*irq_stat);
+
+ /* enable clock switching */
+ asm volatile ("mcr p15, 0, ip, c15, c1, 2" : : : "cc");
+}
+
static int __init ebsa110_init(void)
{
+ arm_pm_idle = ebsa110_idle;
return platform_add_devices(ebsa110_devices, ARRAY_SIZE(ebsa110_devices));
}
--
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