irqchip: Add driver for Cirrus Logic Madera codecs

irqchip: Add driver for Cirrus Logic Madera codecs

The Cirrus Logic Madera codecs (Cirrus Logic CS47L35/85/90/91 and WM1840)
are highly complex devices containing up to 7 programmable DSPs and many
other internal sources of interrupts plus a number of GPIOs that can be
used as interrupt inputs. The large number (>150) of internal interrupt
sources are managed by an on-board interrupt controller.

This driver provides the handling for the interrupt controller. As the
codec is accessed via regmap, we can make use of the generic IRQ
functionality from regmap to do most of the work. Only around half of
the possible interrupt source are currently of interest from the driver
so only this subset is defined. Others can be added in future if needed.

The KConfig options are not user-configurable because this driver is
mandatory so is automatically included when the parent MFD driver is
selected.

Change-Id: Ia6e8581e963368f63fb8b6528236248eeccb47da
Signed-off-by: Richard Fitzgerald <rf@opensource.wolfsonmicro.com>
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>