Add basic support for MCP23017 I/O Expander

drivers/ioexpander/Kconfig

@@ -14,6 +14,50 @@ config IOEXPANDER
 
 if IOEXPANDER
 
+config IOEXPANDER_MCP23X17
+	bool "MCP23017/MCP23S17 I2C/SPI IO expander"
+	default n
+	depends on I2C
+	---help---
+		Enable support for the MCP23017/MCP23S17 IO Expander
+
+if IOEXPANDER_MCP23X17
+
+config MCP23X17_MULTIPLE
+	bool "Multiple MCP23x17 Devices"
+	default n
+	---help---
+		Can be defined to support multiple MCP23x17 devices on board.
+
+config MCP23X17_INT_ENABLE
+	bool "Enable MCP23x17 Interrupt Support"
+	default n
+	select IOEXPANDER_INT_ENABLE
+	---help---
+		Enable driver interrupt functionality
+
+config MCP23X17_INT_NCALLBACKS
+	int "Max number of interrupt callbacks"
+	default 4
+	depends on MCP23X17_INT_ENABLE
+	---help---
+		This is the maximum number of interrupt callbacks supported
+
+config MCP23X17_INT_POLL
+	bool "Enable interrupt poll"
+	default n
+	---help---
+		Enable polling for missed interrupts.
+
+config MCP23X17_INT_POLLDELAY
+	int "Interrupt poll delay (used)"
+	default 500000
+	depends on MCP23X17_INT_POLL
+	---help---
+		This microsecond delay defines the polling rate for missed interrupts.
+
+endif # IOEXPANDER_MCP23X17
+
 config IOEXPANDER_PCA9555
 	bool "PCA9555 I2C IO expander"
 	default n