HID: add hid-cp2112 driver

This patch adds support for the Silicon Labs CP2112 "Single-Chip HID USB to
SMBus Master Bridge."

This is a HID device driver which registers as an i2c adapter and gpiochip to
expose these functions of the CP2112. The customizable USB descriptor fields
are exposed as sysfs attributes.  The SMBus byte-read, byte-data-read/write,
and word-data-read transfer modes have been tested by talking to an i2c
sensor.  The GPIO functions and USB descriptor field programming have also
been tested.
Signed-off-by: David Barksdale <dbarksdale@uplogix.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/Kconfig

@@ -175,6 +175,15 @@ config HID_PRODIKEYS
 	  multimedia keyboard, but will lack support for the musical keyboard
 	  and some additional multimedia keys.
 
+config HID_CP2112
+	tristate "Silicon Labs CP2112 HID USB-to-SMBus Bridge support"
+	depends on USB_HID && I2C
+	---help---
+	Support for Silicon Labs CP2112 HID USB to SMBus Master Bridge.
+	This is a HID device driver which registers as an i2c adapter
+	and gpiochip to expose these functions of the CP2112. The
+	customizable USB descriptor fields are exposed as sysfs attributes.
+
 config HID_CYPRESS
 	tristate "Cypress mouse and barcode readers" if EXPERT
 	depends on HID

drivers/hid/Makefile

@@ -41,6 +41,7 @@ obj-$(CONFIG_HID_AUREAL)        += hid-aureal.o
 obj-$(CONFIG_HID_BELKIN)	+= hid-belkin.o
 obj-$(CONFIG_HID_CHERRY)	+= hid-cherry.o
 obj-$(CONFIG_HID_CHICONY)	+= hid-chicony.o
+obj-$(CONFIG_HID_CP2112)	+= hid-cp2112.o
 obj-$(CONFIG_HID_CYPRESS)	+= hid-cypress.o
 obj-$(CONFIG_HID_DRAGONRISE)	+= hid-dr.o
 obj-$(CONFIG_HID_EMS_FF)	+= hid-emsff.o

drivers/hid/hid-core.c

@@ -1692,6 +1692,7 @@ static const struct hid_device_id hid_have_special_driver[] = {
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CHICONY, USB_DEVICE_ID_CHICONY_WIRELESS2) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CHICONY, USB_DEVICE_ID_CHICONY_AK1D) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CREATIVELABS, USB_DEVICE_ID_PRODIKEYS_PCMIDI) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CYGNAL, USB_DEVICE_ID_CYGNAL_CP2112) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CYPRESS, USB_DEVICE_ID_CYPRESS_BARCODE_1) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CYPRESS, USB_DEVICE_ID_CYPRESS_BARCODE_2) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_CYPRESS, USB_DEVICE_ID_CYPRESS_BARCODE_3) },

drivers/hid/hid-ids.h

@@ -240,6 +240,7 @@
 
 #define USB_VENDOR_ID_CYGNAL		0x10c4
 #define USB_DEVICE_ID_CYGNAL_RADIO_SI470X	0x818a
+#define USB_DEVICE_ID_CYGNAL_CP2112	0xea90
 
 #define USB_VENDOR_ID_CYPRESS		0x04b4
 #define USB_DEVICE_ID_CYPRESS_MOUSE	0x0001