mfd: Add HTCPLD driver

This change introduces a driver for the HTC PLD chip found
on some smartphones, such as the HTC Wizard and HTC Herald.
It works through the I2C bus and acts as a GPIO extender.
Specifically:

 * it can have several sub-devices, each with its own I2C
   address
 * Each sub-device provides 8 output and 8 input pins
 * The chip attaches to one GPIO to signal when any of the
   input GPIOs change -- at which point all chips must be
   scanned for changes

This driver implements the GPIOs throught the kernel's
GPIO and IRQ framework.  This allows any GPIO-servicing
drivers to operate on htcpld pins, such as the gpio-keys
and gpio-leds drivers.

Signed-off-by: Cory Maccarrone <darkstar6262@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/mfd/Kconfig

@@ -78,6 +78,15 @@ config HTC_PASIC3
 	  HTC Magician devices, respectively. Actual functionality is
 	  handled by the leds-pasic3 and ds1wm drivers.
 
+config HTC_I2CPLD
+	bool "HTC I2C PLD chip support"
+	depends on I2C=y
+	help
+	  If you say yes here you get support for the supposed CPLD
+	  found on omap850 HTC devices like the HTC Wizard and HTC Herald.
+	  This device provides input and output GPIOs through an I2C
+	  interface to one or more sub-chips.
+
 config UCB1400_CORE
 	tristate "Philips UCB1400 Core driver"
 	depends on AC97_BUS

drivers/mfd/Makefile

@@ -10,6 +10,7 @@ obj-$(CONFIG_MFD_SH_MOBILE_SDHI)		+= sh_mobile_sdhi.o
 
 obj-$(CONFIG_HTC_EGPIO)		+= htc-egpio.o
 obj-$(CONFIG_HTC_PASIC3)	+= htc-pasic3.o
+obj-$(CONFIG_HTC_I2CPLD)	+= htc-i2cpld.o
 
 obj-$(CONFIG_MFD_DM355EVM_MSP)	+= dm355evm_msp.o