HID: Add driver for USB ELAN Touchpad

This is driver for usb touchpad found on HP Pavilion x2 10-p0xx laptop. On this
device keyboard and touchpad connected as a single usb device with two
interfaces: keyboard, which exposes ordinary keys and second interface is
touchpad which also contains FlightMode button and audio mute led (which
physically placed on keyboard for some reason).

Initially, this touchpad works in mouse emulation mode, this driver will switch
it to touchpad mode, which can track 5 fingers and can report coordinates for
two of them.
Signed-off-by: Alexandrov Stansilav <neko@nya.ai>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/Kconfig

@@ -274,6 +274,14 @@ config HID_EMS_FF
 	Currently the following devices are known to be supported:
 	 - Trio Linker Plus II
 
+config HID_ELAN
+	tristate "ELAN USB Touchpad Support"
+	depends on LEDS_CLASS && USB_HID
+	---help---
+	Say Y to enable support for the USB ELAN touchpad
+	Currently the following devices are known to be supported:
+	 - HP Pavilion X2 10-p0XX.
+
 config HID_ELECOM
 	tristate "ELECOM HID devices"
 	depends on HID

drivers/hid/Makefile

@@ -39,6 +39,7 @@ 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
+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

drivers/hid/hid-ids.h

@@ -368,6 +368,7 @@
 #define USB_DEVICE_ID_DWAV_EGALAX_MULTITOUCH_A001	0xa001
 
 #define USB_VENDOR_ID_ELAN		0x04f3
+#define USB_DEVICE_ID_HP_X2_10_COVER	0x0755
 
 #define USB_VENDOR_ID_ELECOM		0x056e
 #define USB_DEVICE_ID_ELECOM_BM084	0x0061

drivers/hid/hid-quirks.c

@@ -333,6 +333,9 @@ static const struct hid_device_id hid_have_special_driver[] = {
 	{ HID_USB_DEVICE(USB_VENDOR_ID_DRAGONRISE, 0x0006) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_DRAGONRISE, 0x0011) },
 #endif
+#if IS_ENABLED(CONFIG_HID_ELAN)
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELAN, USB_DEVICE_ID_HP_X2_10_COVER) },
+#endif
 #if IS_ENABLED(CONFIG_HID_ELECOM)
 	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_BM084) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_EX_G_WIRED) },