HID: add driver for U2F Zero built-in LED and RNG

U2F Zero supports custom commands for blinking the LED and getting data
from the internal hardware RNG. Expose the blinking function as a LED
device, and the internal hardware RNG as an HWRNG so that it can be used
to feed the enthropy pool.

Signed-off-by: Andrej Shadura <[email protected]>
Signed-off-by: Jiri Kosina <[email protected]>

Author: andrewshadura

drivers/hid/Kconfig

@@ -1003,6 +1003,21 @@ config HID_UDRAW_PS3
 	  Say Y here if you want to use the THQ uDraw gaming tablet for
 	  the PS3.
 
+config HID_U2FZERO
+	tristate "U2F Zero LED and RNG support"
+	depends on USB_HID
+	depends on LEDS_CLASS
+	help
+	  Support for the LED of the U2F Zero device.
+
+	  U2F Zero supports custom commands for blinking the LED
+	  and getting data from the internal hardware RNG.
+	  The internal hardware can be used to feed the enthropy pool.
+
+	  U2F Zero only supports blinking its LED, so this driver doesn't
+	  allow setting the brightness to anything but 1, which will
+	  trigger a single blink and immediately reset to back 0.
+
 config HID_WACOM
 	tristate "Wacom Intuos/Graphire tablet support (USB)"
 	depends on USB_HID

drivers/hid/Makefile

@@ -109,6 +109,7 @@ obj-$(CONFIG_HID_THRUSTMASTER)	+= hid-tmff.o
 obj-$(CONFIG_HID_TIVO)		+= hid-tivo.o
 obj-$(CONFIG_HID_TOPSEED)	+= hid-topseed.o
 obj-$(CONFIG_HID_TWINHAN)	+= hid-twinhan.o
+obj-$(CONFIG_HID_U2FZERO)	+= hid-u2fzero.o
 hid-uclogic-objs		:= hid-uclogic-core.o \
 				   hid-uclogic-rdesc.o \
 				   hid-uclogic-params.o

drivers/hid/hid-ids.h

@@ -323,6 +323,7 @@
 #define USB_DEVICE_ID_CYGNAL_RADIO_SI470X	0x818a
 #define USB_DEVICE_ID_FOCALTECH_FTXXXX_MULTITOUCH	0x81b9
 #define USB_DEVICE_ID_CYGNAL_CP2112	0xea90
+#define USB_DEVICE_ID_U2F_ZERO		0x8acf
 
 #define USB_DEVICE_ID_CYGNAL_RADIO_SI4713       0x8244