irq-imgpdc: add ImgTec PDC irqchip driver

Add irqchip driver for the ImgTec PowerDown Controller (PDC) as found in
the TZ1090. The PDC has a number of general system wakeup (SysWake)
interrupts (which would for example be connected to a power button or an
external peripheral), and a number of peripheral interrupts which can
also wake the system but are connected straight to specific low-power
peripherals (such as RTC or Infrared). It has a single interrupt output
for SysWakes, and individual interrupt outputs for each peripheral.

The driver demuxes the SysWake interrupt line, and passes the peripheral
interrupts straight through. It also handles the set_wake interrupt
operation to enable/disable the appropriate wake event bits.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Rob Landley <rob@landley.net>
Cc: linux-metag@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: devicetree-discuss@lists.ozlabs.org

Documentation/devicetree/bindings/metag/pdc-intc.txt

+* ImgTec Powerdown Controller (PDC) Interrupt Controller Binding
+
+This binding specifies what properties must be available in the device tree
+representation of a PDC IRQ controller. This has a number of input interrupt
+lines which can wake the system, and are passed on through output interrupt
+lines.
+
+Required properties:
+
+    - compatible: Specifies the compatibility list for the interrupt controller.
+      The type shall be <string> and the value shall include "img,pdc-intc".
+
+    - reg: Specifies the base PDC physical address(s) and size(s) of the
+      addressable register space. The type shall be <prop-encoded-array>.
+
+    - interrupt-controller: The presence of this property identifies the node
+      as an interrupt controller. No property value shall be defined.
+
+    - #interrupt-cells: Specifies the number of cells needed to encode an
+      interrupt source. The type shall be a <u32> and the value shall be 2.
+
+    - num-perips: Number of waking peripherals.
+
+    - num-syswakes: Number of SysWake inputs.
+
+    - interrupts: List of interrupt specifiers. The first specifier shall be the
+      shared SysWake interrupt, and remaining specifies shall be PDC peripheral
+      interrupts in order.
+
+* Interrupt Specifier Definition
+
+  Interrupt specifiers consists of 2 cells encoded as follows:
+
+    - <1st-cell>: The interrupt-number that identifies the interrupt source.
+                    0-7:  Peripheral interrupts
+                    8-15: SysWake interrupts
+
+    - <2nd-cell>: The level-sense information, encoded using the Linux interrupt
+                  flags as follows (only 4 valid for peripheral interrupts):
+                    0 = none (decided by software)
+                    1 = low-to-high edge triggered
+                    2 = high-to-low edge triggered
+                    3 = both edge triggered
+                    4 = active-high level-sensitive (required for perip irqs)
+                    8 = active-low level-sensitive
+
+* Examples
+
+Example 1:
+
+	/*
+	 * TZ1090 PDC block
+	 */
+	pdc: pdc@0x02006000 {
+		// This is an interrupt controller node.
+		interrupt-controller;
+
+		// Three cells to encode interrupt sources.
+		#interrupt-cells = <2>;
+
+		// Offset address of 0x02006000 and size of 0x1000.
+		reg = <0x02006000 0x1000>;
+
+		// Compatible with Meta hardware trigger block.
+		compatible = "img,pdc-intc";
+
+		// Three peripherals are connected.
+		num-perips = <3>;
+
+		// Four SysWakes are connected.
+		num-syswakes = <4>;
+
+		interrupts = <18 4 /* level */>, /* Syswakes */
+			     <30 4 /* level */>, /* Peripheral 0 (RTC) */
+			     <29 4 /* level */>, /* Peripheral 1 (IR) */
+			     <31 4 /* level */>; /* Peripheral 2 (WDT) */
+	};
+
+Example 2:
+
+	/*
+	 * An SoC peripheral that is wired through the PDC.
+	 */
+	rtc0 {
+		// The interrupt controller that this device is wired to.
+		interrupt-parent = <&pdc>;
+
+		// Interrupt source Peripheral 0
+		interrupts = <0   /* Peripheral 0 (RTC) */
+		              4>  /* IRQ_TYPE_LEVEL_HIGH */
+	};
+
+Example 3:
+
+	/*
+	 * An interrupt generating device that is wired to a SysWake pin.
+	 */
+	touchscreen0 {
+		// The interrupt controller that this device is wired to.
+		interrupt-parent = <&pdc>;
+
+		// Interrupt source SysWake 0 that is active-low level-sensitive
+		interrupts = <8 /* SysWake0 */
+			      8 /* IRQ_TYPE_LEVEL_LOW */>;
+	};

drivers/irqchip/Kconfig

@@ -30,6 +30,11 @@ config ARM_VIC_NR
 	  The maximum number of VICs available in the system, for
 	  power management.
 
+config IMGPDC_IRQ
+	bool
+	select GENERIC_IRQ_CHIP
+	select IRQ_DOMAIN
+
 config ORION_IRQCHIP
 	bool
 	select IRQ_DOMAIN

drivers/irqchip/Makefile

@@ -14,6 +14,7 @@ obj-$(CONFIG_ARCH_SPEAR3XX)		+= spear-shirq.o
 obj-$(CONFIG_ARM_GIC)			+= irq-gic.o
 obj-$(CONFIG_ARM_NVIC)			+= irq-nvic.o
 obj-$(CONFIG_ARM_VIC)			+= irq-vic.o
+obj-$(CONFIG_IMGPDC_IRQ)		+= irq-imgpdc.o
 obj-$(CONFIG_SIRF_IRQ)			+= irq-sirfsoc.o
 obj-$(CONFIG_RENESAS_INTC_IRQPIN)	+= irq-renesas-intc-irqpin.o
 obj-$(CONFIG_RENESAS_IRQC)		+= irq-renesas-irqc.o