irqchip: crossbar: Initialise the crossbar with a safe value

Since crossbar is s/w configurable, the initial settings of the
crossbar cannot be assumed to be sane. This implies that:
a) On initialization all un-reserved crossbars must be initialized to
   a known 'safe' value.
b) When unmapping the interrupt, the safe value must be written to
   ensure that the crossbar mapping matches with interrupt controller
   usage.

So provide a safe value in the dt data to map if
'0' is not safe for the platform and use it during init and unmap

While at this, fix the below checkpatch warning.
Fixes checkpatch warning:
WARNING: Unnecessary space before function pointer arguments
 #37: FILE: drivers/irqchip/irq-crossbar.c:37:
 +	void (*write) (int, int);

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Sricharan R <r.sricharan@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Link: https://lkml.kernel.org/r/1403766634-18543-5-git-send-email-r.sricharan@ti.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/arm/omap/crossbar.txt b/Documentation/devicetree/bindings/arm/omap/crossbar.txt
index 079576573ec0..5f45c78e31a9 100644
--- a/Documentation/devicetree/bindings/arm/omap/crossbar.txt
+++ b/Documentation/devicetree/bindings/arm/omap/crossbar.txt
@@ -22,6 +22,9 @@ Optional properties:
   SOC-specific hard-wiring of those irqs which unexpectedly bypasses the
   crossbar. These irqs have a crossbar register, but still cannot be used.
 
+- ti,irqs-safe-map: integer which maps to a safe configuration to use
+  when the interrupt controller irq is unused (when not provided, default is 0)
+
 Examples:
 		crossbar_mpu: @4a020000 {
 			compatible = "ti,irq-crossbar";