[PATCH v3] Introduce minimal irqchip infrastructure

[Thomas Petazzoni]

Thomas, Rob, Arnd,

Here is a small set of patches that introduces a small irqchip
infrastructure that allows the registration of irqchip drivers without
having each of those drivers to expose a public API in
include/linux/irqchip/ (patch 1/4), moves the only existing irqchip
driver, irq-bcm2835 to this infrastructure (patch 2/4), moves the
irqchip driver for the Armada 370 / Armada XP SoCs to the
drivers/irqchip directory (patch 3/4) and finally adds the
drivers/irqchip directory to the IRQ subsystem entry in the
MAINTAINERS file (patch 4/4).

Changes since v2:

 * Fixed the entry in the MAINTAINERS file. Noticed by Rob Herring.

 * Simplified the Kconfig logic by making the IRQCHIP option enabled
   by default as soon as OF_IRQ is enabled. The individual ARCH_<foo>
   Kconfig options no longer have to select IRQCHIP. Also, the option
   was renamed from USE_IRQCHIP to just IRQCHIP. Suggested by Rob
   Herring.

 * Added Reviewed-by tags given by Rob Herring.

Changes since v1:

 * Add a new patch mentionning the drivers/irqchip in the list of
   directories part of the IRQ subsystem maintained by Thomas Gleixner
   in the MAINTAINERS file. Requested by Arnd Bergmann.

 * Reduce the amount of code movement in the irq-bcm2835.c and
   irq-armada-370-xp.c files by using one forward declaration for the
   IRQ handling entry point. Requested by Stephen Warren.

 * Rename the armctrl_of_init() function to bcm2835_irqchip_init() as
   requested by Stephen Warren.

 * Added the formal Acked-by and Reviewed-by received from Stephen
   Warren.

Thanks,

Thomas