HID: ft260: add usb hid to i2c host bridge driver

The FTDI FT260 chip implements USB to I2C/UART bridges through two
USB HID class interfaces. The first - for I2C, and the second for UART.
Each interface is independent, and the kernel detects it as a separate
USB hidraw device.

This commit adds I2C host adapter support.

Signed-off-by: Michael Zaidman <michael.zaidman@gmail.com>
Tested-by: Aaron Jones (FTDI-UK) <aaron.jones@ftdichip.com
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

MAINTAINERS

@@ -7278,6 +7278,13 @@ F:	fs/verity/
 F:	include/linux/fsverity.h
 F:	include/uapi/linux/fsverity.h
 
+FT260 FTDI USB-HID TO I2C BRIDGE DRIVER
+M:	Michael Zaidman <michael.zaidman@gmail.com>
+L:	linux-i2c@vger.kernel.org
+L:	linux-input@vger.kernel.org
+S:	Maintained
+F:	drivers/hid/hid-ft260.c
+
 FUJITSU LAPTOP EXTRAS
 M:	Jonathan Woithe <jwoithe@just42.net>
 L:	platform-driver-x86@vger.kernel.org

drivers/hid/Kconfig

@@ -351,6 +351,17 @@ config HID_EZKEY
 	help
 	Support for Ezkey BTC 8193 keyboard.
 
+config HID_FT260
+	tristate "FTDI FT260 USB HID to I2C host support"
+	depends on USB_HID && HIDRAW && I2C
+	help
+	  Provides I2C host adapter functionality over USB-HID through FT260
+	  device. The customizable USB descriptor fields are exposed as sysfs
+	  attributes.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called hid-ft260.
+
 config HID_GEMBIRD
 	tristate "Gembird Joypad"
 	depends on HID

drivers/hid/Makefile

@@ -46,6 +46,7 @@ obj-$(CONFIG_HID_ELAN)		+= hid-elan.o
 obj-$(CONFIG_HID_ELECOM)	+= hid-elecom.o
 obj-$(CONFIG_HID_ELO)		+= hid-elo.o
 obj-$(CONFIG_HID_EZKEY)		+= hid-ezkey.o
+obj-$(CONFIG_HID_FT260)		+= hid-ft260.o
 obj-$(CONFIG_HID_GEMBIRD)	+= hid-gembird.o
 obj-$(CONFIG_HID_GFRM)		+= hid-gfrm.o
 obj-$(CONFIG_HID_GLORIOUS)  += hid-glorious.o

drivers/hid/hid-ids.h

@@ -430,6 +430,7 @@
 
 #define USB_VENDOR_ID_FUTURE_TECHNOLOGY	0x0403
 #define USB_DEVICE_ID_RETRODE2		0x97c1
+#define USB_DEVICE_ID_FT260             0x6030
 
 #define USB_VENDOR_ID_ESSENTIAL_REALITY	0x0d7f
 #define USB_DEVICE_ID_ESSENTIAL_REALITY_P5 0x0100