soc: apple: Add DockChannel driver

DockChannel is a simple FIFO interface used to communicate between SoC
blocks. Add a driver that represents the shared interrupt controller for
the DockChannel block, and then exposes probe and data transfer
functions that child device drivers can use to instantiate individual
FIFOs.

Signed-off-by: Hector Martin <marcan@marcan.st>

Author: marcan

drivers/soc/apple/Kconfig

@@ -41,6 +41,16 @@ config APPLE_SART
 
 	  Say 'y' here if you have an Apple SoC.
 
+config APPLE_DOCKCHANNEL
+	tristate "Apple DockChannel FIFO"
+	depends on ARCH_APPLE || COMPILE_TEST
+	default ARCH_APPLE
+	help
+	  DockChannel is a simple FIFO used on Apple SoCs for debug and inter-processor
+	  communications.
+
+	  Say 'y' here if you have an Apple SoC.
+
 endmenu
 
 endif

drivers/soc/apple/Makefile

@@ -8,3 +8,6 @@ apple-rtkit-y = rtkit.o rtkit-crashlog.o
 
 obj-$(CONFIG_APPLE_SART) += apple-sart.o
 apple-sart-y = sart.o
+
+obj-$(CONFIG_APPLE_DOCKCHANNEL) += apple-dockchannel.o
+apple-dockchannel-y = dockchannel.o