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.

---
The MFD dependency is now in Linus's tree so this patch should apply to the irq tree without breaking it.

---
 MAINTAINERS                        |   2 +
 drivers/irqchip/Kconfig            |   3 +
 drivers/irqchip/Makefile           |   1 +
 drivers/irqchip/irq-madera.c       | 256 +++++++++++++++++++++++++++++++++++++
 include/linux/irqchip/irq-madera.h | 132 +++++++++++++++++++
 5 files changed, 394 insertions(+)
 create mode 100644 drivers/irqchip/irq-madera.c
 create mode 100644 include/linux/irqchip/irq-madera.h

index f4855974f325..9060061f15f1 100644
@@ -3604,8 +3604,10 @@ W:	https://github.com/CirrusLogic/linux-drivers/wiki
 S:	Supported
 F:	Documentation/devicetree/bindings/mfd/madera.txt
 F:	Documentation/devicetree/bindings/pinctrl/cirrus,madera-pinctrl.txt
+F:	include/linux/irqchip/irq-madera*
 F:	include/linux/mfd/madera/*
 F:	drivers/gpio/gpio-madera*
+F:	drivers/irqchip/irq-madera*
 F:	drivers/mfd/madera*
 F:	drivers/mfd/cs47l*
 F:	drivers/pinctrl/cirrus/*

index 51a5ef0e96ed..a7252da28305 100644
@@ -150,6 +150,9 @@ config IMGPDC_IRQ
 	select GENERIC_IRQ_CHIP
 	select IRQ_DOMAIN
 
+config MADERA_IRQ
+	tristate
+
 config IRQ_MIPS_CPU
 	bool
 	select GENERIC_IRQ_CHIP

index 794c13d3ac3d..3dcea8a6e5de 100644
@@ -91,3 +91,4 @@ obj-$(CONFIG_QCOM_PDC)			+= qcom-pdc.o
 obj-$(CONFIG_CSKY_MPINTC)		+= irq-csky-mpintc.o
 obj-$(CONFIG_CSKY_APB_INTC)		+= irq-csky-apb-intc.o
 obj-$(CONFIG_SIFIVE_PLIC)		+= irq-sifive-plic.o
+obj-$(CONFIG_MADERA_IRQ)		+= irq-madera.o

2.11.0