Provide an implementation to fix RTC irqs before enabling the irqchip.

This was previously done in arch/arm/mach-at91/sysirq_mask.c but as we're
trying to use standard implementation (IRQCHIP_DECLARE and automatic call
of irqchip_init within arch/arm/kernel/irq.c) we need to do those fixups
in the irqchip driver.
Signed-off-by: NBoris BREZILLON <boris.brezillon@free-electrons.com>
Link: https://lkml.kernel.org/r/1405016741-2407-3-git-send-email-boris.brezillon@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

Add irq fixup infrastructure to handle IP blocks connected to shared irqs
that are left in an unknown state when booting the kernel.

In this case the IP block which has not masked its interrupt and has no
driver loaded (either because it is not compiled or because it is not
loaded yet) might generate spurious interrupts when another IP block
request the shared irq.

A good example of this case is the RTC block on which register configs are
kept even after a shutdown (if a proper VDDcore is supplied), and thus
might generate spurious interrupts when the platform is switched on.
Signed-off-by: NBoris BREZILLON <boris.brezillon@free-electrons.com>
Link: https://lkml.kernel.org/r/1405016741-2407-2-git-send-email-boris.brezillon@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>

Add AIC (Advanced Interrupt Controller) and AIC5 (AIC5 is an evolution of
the AIC block) drivers.
Put common code in irq-atmel-aic-common.c/.h so that both driver can access
shared functions (this will ease maintenance).

These drivers are only compatible with dt enabled board and replace the
old implementation found in arch/arm/mach-at91/irq.c.
Signed-off-by: NBoris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: NNicolas Ferre <nicolas.ferre@atmel.com>
Link: https://lkml.kernel.org/r/1405012462-766-4-git-send-email-boris.brezillon@free-electrons.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>