i2c: imx-lpi2c: add low power i2c bus driver

This patch adds lpi2c bus driver to support new i.MX products
which use lpi2c instead of the old imx i2c.

The lpi2c can continue operating in stop mode when an appropriate
clock is available. It is also designed for low CPU overhead with
DMA offloading of FIFO register accesses.
Signed-off-by: Gao Pan <pandy.gao@nxp.com>
Reviewed-by: Fugang Duan <B38611@freescale.com>
Reviewed-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/Kconfig

@@ -597,6 +597,16 @@ config I2C_IMX
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-imx.
 
+config I2C_IMX_LPI2C
+	tristate "IMX Low Power I2C interface"
+	depends on ARCH_MXC || COMPILE_TEST
+	help
+          Say Y here if you want to use the Low Power IIC bus controller
+          on the Freescale i.MX processors.
+
+          This driver can also be built as a module. If so, the module
+          will be called i2c-imx-lpi2c.
+
 config I2C_IOP3XX
 	tristate "Intel IOPx3xx and IXP4xx on-chip I2C interface"
 	depends on ARCH_IOP32X || ARCH_IOP33X || ARCH_IXP4XX || ARCH_IOP13XX

drivers/i2c/busses/Makefile

@@ -56,6 +56,7 @@ obj-$(CONFIG_I2C_HIX5HD2)	+= i2c-hix5hd2.o
 obj-$(CONFIG_I2C_IBM_IIC)	+= i2c-ibm_iic.o
 obj-$(CONFIG_I2C_IMG)		+= i2c-img-scb.o
 obj-$(CONFIG_I2C_IMX)		+= i2c-imx.o
+obj-$(CONFIG_I2C_IMX_LPI2C)	+= i2c-imx-lpi2c.o
 obj-$(CONFIG_I2C_IOP3XX)	+= i2c-iop3xx.o
 obj-$(CONFIG_I2C_JZ4780)	+= i2c-jz4780.o
 obj-$(CONFIG_I2C_KEMPLD)	+= i2c-kempld.o