irqchip: renesas-intc-irqpin: DT binding for sense bitfield width

Most Renesas irqpin controllers have 4-bit sense fields, however, some
have different widths. This patch adds a DT binding to optionally
specify such non-standard values.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

Documentation/devicetree/bindings/interrupt-controller/renesas,intc-irqpin.txt

+DT bindings for the R-/SH-Mobile irqpin controller
+
+Required properties:
+
+- compatible: has to be "renesas,intc-irqpin"
+- #interrupt-cells: has to be <2>: an interrupt index and flags, as defined in
+  interrupts.txt in this directory
+
+Optional properties:
+
+- any properties, listed in interrupts.txt, and any standard resource allocation
+  properties
+- sense-bitfield-width: width of a single sense bitfield in the SENSE register,
+  if different from the default 4 bits

drivers/irqchip/irq-renesas-intc-irqpin.c

@@ -18,6 +18,7 @@
  */
 
 #include <linux/init.h>
+#include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/spinlock.h>
 #include <linux/interrupt.h>
@@ -349,6 +350,9 @@ static int intc_irqpin_probe(struct platform_device *pdev)
 	/* deal with driver instance configuration */
 	if (pdata)
 		memcpy(&p->config, pdata, sizeof(*pdata));
+	else
+		of_property_read_u32(pdev->dev.of_node, "sense-bitfield-width",
+				     &p->config.sense_bitfield_width);
 	if (!p->config.sense_bitfield_width)
 		p->config.sense_bitfield_width = 4; /* default to 4 bits */