ARM: tegra114: add low level support for CPU idle powered-down mode

The flow controller would take care the power sequence when CPU idle in
powered-down mode. It powered gate the CPU when CPU runs into WFI
instruction. And wake up the CPU when event be triggered.

The sequence is below.
* setting wfi bitmap for the CPU as the halt event in the
  FLOW_CTRL_CPU_HALT_REG to monitor the CPU running into WFI,then power
  gate it
* setting IRQ and FIQ as wake up event to wake up CPU when event triggered

Signed-off-by: Joseph Lo <josephl@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>

arch/arm/mach-tegra/flowctrl.h

@@ -28,6 +28,8 @@
 #define FLOW_CTRL_SCLK_RESUME		(1 << 27)
 #define FLOW_CTRL_HALT_CPU_IRQ		(1 << 10)
 #define	FLOW_CTRL_HALT_CPU_FIQ		(1 << 8)
+#define FLOW_CTRL_HALT_GIC_IRQ		(1 << 9)
+#define FLOW_CTRL_HALT_GIC_FIQ		(1 << 8)
 #define FLOW_CTRL_CPU0_CSR		0x8
 #define	FLOW_CTRL_CSR_INTR_FLAG		(1 << 15)
 #define FLOW_CTRL_CSR_EVENT_FLAG	(1 << 14)

arch/arm/mach-tegra/sleep-tegra30.S

@@ -99,6 +99,8 @@ flow_ctrl_setting_for_lp2:
 	cmp	r10, #TEGRA30
 	moveq   r3, #FLOW_CTRL_WAIT_FOR_INTERRUPT	@ For LP2
 	movne	r3, #FLOW_CTRL_WAITEVENT
+	orrne	r3, r3, #FLOW_CTRL_HALT_GIC_IRQ
+	orrne	r3, r3, #FLOW_CTRL_HALT_GIC_FIQ
 flow_ctrl_done:
 	cmp	r10, #TEGRA30
 	str	r3, [r2]