USB: add Printer Gadget Driver

G_PRINTER: Adds a USB printer gadget driver for use in printer firmware.

This adds a USB printer gadget driver for use in printer firmware.
The printer gadget channels data between the USB host and a userspace
program driving the print engine. The user space program reads and
writes the device file /dev/g_printer to receive or send printer data.
It can use ioctl calls to the device file to get or set printer status.
Signed-off-by: Craig W. Nadler <craig@nadler.us>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/Kconfig

@@ -548,6 +548,20 @@ config USB_MIDI_GADGET
 	  Say "y" to link the driver statically, or "m" to build a
 	  dynamically linked module called "g_midi".
 
+config USB_G_PRINTER
+	tristate "Printer Gadget"
+	help
+	  The Printer Gadget channels data between the USB host and a
+	  userspace program driving the print engine. The user space
+	  program reads and writes the device file /dev/g_printer to
+	  receive or send printer data. It can use ioctl calls to
+	  the device file to get or set printer status.
+
+	  Say "y" to link the driver statically, or "m" to build a
+	  dynamically linked module called "g_printer".
+
+	  For more information, see Documentation/usb/gadget_printer.txt
+	  which includes sample code for accessing the device file.
 
 # put drivers that need isochronous transfer support (for audio
 # or video class gadget drivers), or specific hardware, here.

drivers/usb/gadget/Makefile

@@ -28,6 +28,8 @@ g_midi-objs			:= gmidi.o usbstring.o config.o epautoconf.o
 gadgetfs-objs			:= inode.o
 g_file_storage-objs		:= file_storage.o usbstring.o config.o \
 					epautoconf.o
+g_printer-objs			:= printer.o usbstring.o config.o \
+					epautoconf.o
 
 ifeq ($(CONFIG_USB_ETH_RNDIS),y)
 	g_ether-objs		+= rndis.o
@@ -38,5 +40,6 @@ obj-$(CONFIG_USB_ETH)		+= g_ether.o
 obj-$(CONFIG_USB_GADGETFS)	+= gadgetfs.o
 obj-$(CONFIG_USB_FILE_STORAGE)	+= g_file_storage.o
 obj-$(CONFIG_USB_G_SERIAL)	+= g_serial.o
+obj-$(CONFIG_USB_G_PRINTER)	+= g_printer.o
 obj-$(CONFIG_USB_MIDI_GADGET)	+= g_midi.o
 

include/linux/usb/Kbuild

@@ -3,4 +3,5 @@ unifdef-y += cdc.h
 unifdef-y += ch9.h
 unifdef-y += gadgetfs.h
 unifdef-y += midi.h
+unifdef-y += g_printer.h
 

include/linux/usb/g_printer.h

+/*
+ * g_printer.h -- Header file for USB Printer gadget driver
+ *
+ * Copyright (C) 2007 Craig W. Nadler
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+
+#define PRINTER_NOT_ERROR	0x08
+#define PRINTER_SELECTED	0x10
+#define PRINTER_PAPER_EMPTY	0x20
+
+/* The 'g' code is also used by gadgetfs ioctl requests.
+ * Don't add any colliding codes to either driver, and keep
+ * them in unique ranges (size 0x20 for now).
+ */
+#define GADGET_GET_PRINTER_STATUS	_IOR('g', 0x21, unsigned char)
+#define GADGET_SET_PRINTER_STATUS	_IOWR('g', 0x22, unsigned char)

include/linux/usb/gadgetfs.h

@@ -59,6 +59,11 @@ struct usb_gadgetfs_event {
 };
 
 
+/* The 'g' code is also used by printer gadget ioctl requests.
+ * Don't add any colliding codes to either driver, and keep
+ * them in unique ranges (size 0x20 for now).
+ */
+
 /* endpoint ioctls */
 
 /* IN transfers may be reported to the gadget driver as complete