NFC: nxp-nci_i2c: Add I2C support to NXP NCI driver

Add a module to the NXP-NCI driver to support NFC controllers with an
I2C control interface, such as the NPC100.

Signed-off-by: Clément Perrochaud <clement.perrochaud@effinnov.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Documentation/devicetree/bindings/net/nfc/nxp-nci.txt

@@ -0,0 +1,35 @@
+* NXP Semiconductors NXP NCI NFC Controllers
+
+Required properties:
+- compatible: Should be "nxp,nxp-nci-i2c".
+- clock-frequency: I²C work frequency.
+- reg: address on the bus
+- interrupt-parent: phandle for the interrupt gpio controller
+- interrupts: GPIO interrupt to which the chip is connected
+- enable-gpios: Output GPIO pin used for enabling/disabling the chip
+- firmware-gpios: Output GPIO pin used to enter firmware download mode
+
+Optional SoC Specific Properties:
+- pinctrl-names: Contains only one value - "default".
+- pintctrl-0: Specifies the pin control groups used for this controller.
+
+Example (for ARM-based BeagleBone with NPC100 NFC controller on I2C2):
+
+&i2c2 {
+
+	status = "okay";
+
+	npc100: npc100@29 {
+
+		compatible = "nxp,nxp-nci-i2c";
+
+		reg = <0x29>;
+		clock-frequency = <100000>;
+
+		interrupt-parent = <&gpio1>;
+		interrupts = <29 GPIO_ACTIVE_HIGH>;
+
+		enable-gpios = <&gpio0 30 GPIO_ACTIVE_HIGH>;
+		firmware-gpios = <&gpio0 31 GPIO_ACTIVE_HIGH>;
+	};
+};

drivers/nfc/nxp-nci/Kconfig

@@ -11,3 +11,15 @@ config NFC_NXP_NCI
 	  To compile this driver as a module, choose m here. The module will
 	  be called nxp_nci.
 	  Say N if unsure.
+
+config NFC_NXP_NCI_I2C
+	tristate "NXP-NCI I2C support"
+	depends on NFC_NXP_NCI && I2C
+	---help---
+	  This module adds support for an I2C interface to the NXP NCI
+	  chips.
+	  Select this if your platform is using the I2C bus.
+
+	  To compile this driver as a module, choose m here. The module will
+	  be called nxp_nci_i2c.
+	  Say Y if unsure.

drivers/nfc/nxp-nci/Makefile

@@ -3,7 +3,9 @@
 #
 
 nxp-nci-objs = core.o firmware.o
+nxp-nci_i2c-objs = i2c.o
 
 obj-$(CONFIG_NFC_NXP_NCI) += nxp-nci.o
+obj-$(CONFIG_NFC_NXP_NCI_I2C) += nxp-nci_i2c.o
 
 ccflags-$(CONFIG_NFC_DEBUG) := -DDEBUG