usb: gadget: Add snapshot of USB CDEV function driver

This change adds USB CDEV function driver which creates USB
character device to provide DUN and NMEA functionality.
This snapshot is taken as of msm-4.19 commit 104eef6e1fe8 ("platform:
msm: Remove unused local count variable").

Change-Id: I2a20aec1c21a506f8981e907bc0f0f58fff7fe58
Signed-off-by: Jack Pham <jackp@codeaurora.org>

drivers/usb/gadget/Kconfig

@@ -231,6 +231,9 @@ config USB_F_QDSS
 config USB_F_CCID
 	tristate
 
+config USB_F_CDEV
+	tristate
+
 # this first set of drivers all depend on bulk-capable hardware.
 
 config USB_CONFIGFS
@@ -555,6 +558,18 @@ config USB_CONFIGFS_F_CCID
 	  allowing a userspace component to be able to provide the
 	  implementation necessary to interface with the smartcard.
 
+config USB_CONFIGFS_F_CDEV
+	tristate "USB Serial Character function"
+	select USB_F_CDEV
+	depends on USB_CONFIGFS
+	help
+	  The serial character function is a generic function driver that
+	  exposes a pair of bulk IN and OUT endpoints which are backed by
+	  a character device and mapped to its read/write routines. The
+	  function also supports a single interrupt IN endpoint for
+	  asynchronous notification to the host. This driver is typically
+	  used to support DUN/NMEA functions.
+
 choice
 	tristate "USB Gadget precomposed configurations"
 	default USB_ETH

drivers/usb/gadget/function/Makefile

@@ -60,3 +60,5 @@ usb_f_qdss-y			:= f_qdss.o u_qdss.o
 obj-$(CONFIG_USB_F_QDSS)	+= usb_f_qdss.o
 usb_f_ccid-y			:= f_ccid.o
 obj-$(CONFIG_USB_F_CCID)	+= usb_f_ccid.o
+usb_f_cdev-y			:= f_cdev.o
+obj-$(CONFIG_USB_F_CDEV)	+= usb_f_cdev.o