arm/tegra: Harmony: Configure PMC for low-level interrupts

Without this, the PMC continually detects an interrupt when the PMU_IRQ
line is high, causing the tps6686x IRQ handler thread to hog an entire
CPU.

This change was originally written by Wei Ni <wni@nvidia.com> for Seaboard
in the ChromeOS kernel.

Long-term, this should probably be moved into some kind of PMU driver,
or perhaps integrated into the GPIO/IRQ/pinmux system?
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Olof Johansson <olof@lixom.net>

arch/arm/mach-tegra/board-harmony-power.c

@@ -18,10 +18,11 @@
 #include <linux/i2c.h>
 #include <linux/platform_device.h>
 #include <linux/gpio.h>
-
+#include <linux/io.h>
 #include <linux/regulator/machine.h>
 #include <linux/mfd/tps6586x.h>
 
+#include <mach/iomap.h>
 #include <mach/irqs.h>
 
 #include "board-harmony.h"
@@ -113,6 +114,16 @@ static struct i2c_board_info __initdata harmony_regulators[] = {
 
 int __init harmony_regulator_init(void)
 {
+	void __iomem *pmc = IO_ADDRESS(TEGRA_PMC_BASE);
+	u32 pmc_ctrl;
+
+	/*
+	 * Configure the power management controller to trigger PMU
+	 * interrupts when low
+	 */
+	pmc_ctrl = readl(pmc + PMC_CTRL);
+	writel(pmc_ctrl | PMC_CTRL_INTR_LOW, pmc + PMC_CTRL);
+
 	i2c_register_board_info(3, harmony_regulators, 1);
 
 	return 0;