This adds support for Vybrid's interrupt router. On VF6xx models,
almost all peripherals can be used by either of the two CPU's,
the Cortex-A5 or the Cortex-M4. The interrupt router routes the
peripheral interrupts to the configured CPU.

This IRQ chip driver configures the interrupt router to route
the requested interrupt to the CPU the kernel is running on.
The driver makes use of the irqdomain hierarchy support. The
parent is given by the device tree. This should be one of the
two possible parents either ARM GIC or the ARM NVIC interrupt
controller. The latter is currently not yet supported.

Note that there is no resource control mechnism implemented to
avoid concurrent access of the same peripheral. The user needs
to make sure to use device trees which assign the peripherals
orthogonally. However, this driver warns the user in case the
interrupt is already configured for the other CPU. This provides
a poor man's resource controller.

Acked-by: Marc Zyngier <redacted>
Signed-off-by: Stefan Agner <stefan@agner.ch>
---
 arch/arm/mach-imx/Kconfig           |   1 +
 drivers/irqchip/Kconfig             |  11 ++
 drivers/irqchip/Makefile            |   1 +
 drivers/irqchip/irq-vf610-mscm-ir.c | 206 ++++++++++++++++++++++++++++++++++++
 4 files changed, 219 insertions(+)
 create mode 100644 drivers/irqchip/irq-vf610-mscm-ir.c

diff --git a/arch/arm/mach-imx/Kconfig b/arch/arm/mach-imx/Kconfig
index e8627e0..bf91a59 100644
--- a/arch/arm/mach-imx/Kconfig
+++ b/arch/arm/mach-imx/Kconfig

@@ -631,6 +631,7 @@ config SOC_IMX6SX
 
 config SOC_VF610
 	bool "Vybrid Family VF610 support"
+	select VF610_MSCM_IR
 	select ARM_GIC
 	select PINCTRL_VF610
 	select PL310_ERRATA_769419 if CACHE_L2X0

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index cc79d2a..9c13d81 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig

@@ -136,6 +136,17 @@ config IRQ_CROSSBAR
 	  a free irq and configures the IP. Thus the peripheral interrupts are
 	  routed to one of the free irqchip interrupt lines.
 
+config VF610_MSCM_IR
+	bool
+	help
+	  Support for MSCM interrupt router available on Vybrid SoC's. The
+	  interrupt router is between the CPU's interrupt controller and the
+	  peripheral. The router allows to route the peripheral interrupts to
+	  one of the two available CPU's on Vybrid VF6xx SoC's (Cortex-A5 or
+	  Cortex-M4). The router will be configured transparently on a IRQ
+	  request.
+	select IRQ_DOMAIN_HIERARCHY
+