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>

Documentation/usb/gadget_printer.txt

+
+                       Linux USB Printer Gadget Driver
+                                 06/04/2007
+
+              Copyright (C) 2007 Craig W. Nadler <craig@nadler.us>
+
+
+
+GENERAL
+=======
+
+This driver may be used if you are writing printer firmware using Linux as
+the embedded OS. This driver has nothing to do with using a printer with
+your Linux host system.
+
+You will need a USB device controller and a Linux driver for it that accepts
+a gadget / "device class" driver using the Linux USB Gadget API. After the
+USB device controller driver is loaded then load the printer gadget driver.
+This will present a printer interface to the USB Host that your USB Device
+port is connected to.
+
+This driver is structured for printer firmware that runs in user mode. The
+user mode printer firmware will read and write data from the kernel mode
+printer gadget driver using a device file. The printer returns a printer status
+byte when the USB HOST sends a device request to get the printer status.  The
+user space firmware can read or write this status byte using a device file
+/dev/g_printer . Both blocking and non-blocking read/write calls are supported.
+
+
+
+
+HOWTO USE THIS DRIVER
+=====================
+
+To load the USB device controller driver and the printer gadget driver. The
+following example uses the Netchip 2280 USB device controller driver:
+
+modprobe net2280
+modprobe g_printer
+
+
+The follow command line parameter can be used when loading the printer gadget
+(ex: modprobe g_printer idVendor=0x0525 idProduct=0xa4a8 ):
+
+idVendor - This is the Vendor ID used in the device descriptor. The default is
+	the Netchip vendor id 0x0525. YOU MUST CHANGE TO YOUR OWN VENDOR ID
+	BEFORE RELEASING A PRODUCT. If you plan to release a product and don't
+	already have a Vendor ID please see www.usb.org for details on how to
+	get one.
+
+idProduct - This is the Product ID used in the device descriptor. The default
+	is 0xa4a8, you should change this to an ID that's not used by any of
+	your other USB products if you have any. It would be a good idea to
+	start numbering your products starting with say 0x0001.
+
+bcdDevice - This is the version number of your product. It would be a good idea
+	to put your firmware version here.
+
+iManufacturer - A string containing the name of the Vendor.
+
+iProduct - A string containing the Product Name.
+
+iSerialNum - A string containing the Serial Number. This should be changed for
+	each unit of your product.
+
+iPNPstring -  The PNP ID string used for this printer. You will want to set
+	either on the command line or hard code the PNP ID string used for
+	your printer product.
+
+qlen - The number of 8k buffers to use per endpoint. The default is 10, you
+	should tune this for your product. You may also want to tune the
+	size of each buffer for your product.
+
+
+
+
+USING THE EXAMPLE CODE
+======================
+
+This example code talks to stdout, instead of a print engine.
+
+To compile the test code below:
+
+1) save it to a file called prn_example.c
+2) compile the code with the follow command:
+	 gcc prn_example.c -o prn_example
+
+
+
+To read printer data from the host to stdout:
+
+	# prn_example -read_data
+
+
+To write printer data from a file (data_file) to the host:
+
+	# cat data_file | prn_example -write_data
+
+
+To get the current printer status for the gadget driver:
+
+	# prn_example -get_status
+
+	Printer status is:
+	     Printer is NOT Selected
+	     Paper is Out
+	     Printer OK
+
+
+To set printer to Selected/On-line:
+
+	# prn_example -selected
+
+
+To set printer to Not Selected/Off-line:
+
+	# prn_example -not_selected
+
+
+To set paper status to paper out:
+
+	# prn_example -paper_out
+
+
+To set paper status to paper loaded:
+
+	# prn_example -paper_loaded
+
+
+To set error status to printer OK:
+
+	# prn_example -no_error
+
+
+To set error status to ERROR:
+
+	# prn_example -error
+
+
+
+
+EXAMPLE CODE
+============
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <linux/poll.h>
+#include <sys/ioctl.h>
+#include <linux/usb/g_printer.h>
+
+#define PRINTER_FILE			"/dev/g_printer"
+#define BUF_SIZE			512
+
+
+/*
+ * 'usage()' - Show program usage.
+ */
+
+static void
+usage(const char *option)		/* I - Option string or NULL */
+{
+	if (option) {
+		fprintf(stderr,"prn_example: Unknown option \"%s\"!\n",
+				option);
+	}
+
+	fputs("\n", stderr);
+	fputs("Usage: prn_example -[options]\n", stderr);
+	fputs("Options:\n", stderr);
+	fputs("\n", stderr);
+	fputs("-get_status    Get the current printer status.\n", stderr);
+	fputs("-selected      Set the selected status to selected.\n", stderr);
+	fputs("-not_selected  Set the selected status to NOT selected.\n",
+			stderr);
+	fputs("-error         Set the error status to error.\n", stderr);
+	fputs("-no_error      Set the error status to NO error.\n", stderr);
+	fputs("-paper_out     Set the paper status to paper out.\n", stderr);
+	fputs("-paper_loaded  Set the paper status to paper loaded.\n",
+			stderr);
+	fputs("-read_data     Read printer data from driver.\n", stderr);
+	fputs("-write_data    Write printer sata to driver.\n", stderr);
+	fputs("-NB_read_data  (Non-Blocking) Read printer data from driver.\n",
+			stderr);
+	fputs("\n\n", stderr);
+
+	exit(1);
+}
+
+
+static int
+read_printer_data()
+{
+	struct pollfd	fd[1];
+
+	/* Open device file for printer gadget. */
+	fd[0].fd = open(PRINTER_FILE, O_RDWR);
+	if (fd[0].fd < 0) {
+		printf("Error %d opening %s\n", fd[0].fd, PRINTER_FILE);
+		close(fd[0].fd);
+		return(-1);
+	}
+
+	fd[0].events = POLLIN | POLLRDNORM;
+
+	while (1) {
+		static char buf[BUF_SIZE];
+		int bytes_read;
+		int retval;
+
+		/* Wait for up to 1 second for data. */
+		retval = poll(fd, 1, 1000);
+
+		if (retval && (fd[0].revents & POLLRDNORM)) {
+
+			/* Read data from printer gadget driver. */
+			bytes_read = read(fd[0].fd, buf, BUF_SIZE);
+
+			if (bytes_read < 0) {
+				printf("Error %d reading from %s\n",
+						fd[0].fd, PRINTER_FILE);
+				close(fd[0].fd);
+				return(-1);
+			} else if (bytes_read > 0) {
+				/* Write data to standard OUTPUT (stdout). */
+				fwrite(buf, 1, bytes_read, stdout);
+				fflush(stdout);
+			}
+
+		}
+
+	}
+
+	/* Close the device file. */
+	close(fd[0].fd);
+
+	return 0;
+}
+
+
+static int
+write_printer_data()
+{
+	struct pollfd	fd[1];
+
+	/* Open device file for printer gadget. */
+	fd[0].fd = open (PRINTER_FILE, O_RDWR);
+	if (fd[0].fd < 0) {
+		printf("Error %d opening %s\n", fd[0].fd, PRINTER_FILE);
+		close(fd[0].fd);
+		return(-1);
+	}
+
+	fd[0].events = POLLOUT | POLLWRNORM;
+
+	while (1) {
+		int retval;
+		static char buf[BUF_SIZE];
+		/* Read data from standard INPUT (stdin). */
+		int bytes_read = fread(buf, 1, BUF_SIZE, stdin);
+
+		if (!bytes_read) {
+			break;
+		}
+
+		while (bytes_read) {
+
+			/* Wait for up to 1 second to sent data. */
+			retval = poll(fd, 1, 1000);
+
+			/* Write data to printer gadget driver. */
+			if (retval && (fd[0].revents & POLLWRNORM)) {
+				retval = write(fd[0].fd, buf, bytes_read);
+				if (retval < 0) {
+					printf("Error %d writing to %s\n",
+							fd[0].fd,
+							PRINTER_FILE);
+					close(fd[0].fd);
+					return(-1);
+				} else {
+					bytes_read -= retval;
+				}
+
+			}
+
+		}
+
+	}
+
+	/* Wait until the data has been sent. */
+	fsync(fd[0].fd);
+
+	/* Close the device file. */
+	close(fd[0].fd);
+
+	return 0;
+}
+
+
+static int
+read_NB_printer_data()
+{
+	int		fd;
+	static char	buf[BUF_SIZE];
+	int		bytes_read;
+
+	/* Open device file for printer gadget. */
+	fd = open(PRINTER_FILE, O_RDWR|O_NONBLOCK);
+	if (fd < 0) {
+		printf("Error %d opening %s\n", fd, PRINTER_FILE);
+		close(fd);
+		return(-1);
+	}
+
+	while (1) {
+		/* Read data from printer gadget driver. */
+		bytes_read = read(fd, buf, BUF_SIZE);
+		if (bytes_read <= 0) {
+			break;
+		}
+
+		/* Write data to standard OUTPUT (stdout). */
+		fwrite(buf, 1, bytes_read, stdout);
+		fflush(stdout);
+	}
+
+	/* Close the device file. */
+	close(fd);
+
+	return 0;
+}
+
+
+static int
+get_printer_status()
+{
+	int	retval;
+	int	fd;
+
+	/* Open device file for printer gadget. */
+	fd = open(PRINTER_FILE, O_RDWR);
+	if (fd < 0) {
+		printf("Error %d opening %s\n", fd, PRINTER_FILE);
+		close(fd);
+		return(-1);
+	}
+
+	/* Make the IOCTL call. */
+	retval = ioctl(fd, GADGET_GET_PRINTER_STATUS);
+	if (retval < 0) {
+		fprintf(stderr, "ERROR: Failed to set printer status\n");
+		return(-1);
+	}
+
+	/* Close the device file. */
+	close(fd);
+
+	return(retval);
+}
+
+
+static int
+set_printer_status(unsigned char buf, int clear_printer_status_bit)
+{
+	int	retval;
+	int	fd;
+
+	retval = get_printer_status();
+	if (retval < 0) {
+		fprintf(stderr, "ERROR: Failed to get printer status\n");
+		return(-1);
+	}
+
+	/* Open device file for printer gadget. */
+	fd = open(PRINTER_FILE, O_RDWR);
+
+	if (fd < 0) {
+		printf("Error %d opening %s\n", fd, PRINTER_FILE);
+		close(fd);
+		return(-1);
+	}
+
+	if (clear_printer_status_bit) {
+		retval &= ~buf;
+	} else {
+		retval |= buf;
+	}
+
+	/* Make the IOCTL call. */
+	if (ioctl(fd, GADGET_SET_PRINTER_STATUS, (unsigned char)retval)) {
+		fprintf(stderr, "ERROR: Failed to set printer status\n");
+		return(-1);
+	}
+
+	/* Close the device file. */
+	close(fd);
+
+	return 0;
+}
+
+
+static int
+display_printer_status()
+{
+	char	printer_status;
+
+	printer_status = get_printer_status();
+	if (printer_status < 0) {
+		fprintf(stderr, "ERROR: Failed to get printer status\n");
+		return(-1);
+	}
+
+	printf("Printer status is:\n");
+	if (printer_status & PRINTER_SELECTED) {
+		printf("     Printer is Selected\n");
+	} else {
+		printf("     Printer is NOT Selected\n");
+	}
+	if (printer_status & PRINTER_PAPER_EMPTY) {
+		printf("     Paper is Out\n");
+	} else {
+		printf("     Paper is Loaded\n");
+	}
+	if (printer_status & PRINTER_NOT_ERROR) {
+		printf("     Printer OK\n");
+	} else {
+		printf("     Printer ERROR\n");
+	}
+
+	return(0);
+}
+
+
+int
+main(int  argc, char *argv[])
+{
+	int	i;		/* Looping var */
+	int	retval = 0;
+
+	/* No Args */
+	if (argc == 1) {
+		usage(0);
+		exit(0);
+	}
+
+	for (i = 1; i < argc && !retval; i ++) {
+
+		if (argv[i][0] != '-') {
+			continue;
+		}
+
+		if (!strcmp(argv[i], "-get_status")) {
+			if (display_printer_status()) {
+				retval = 1;
+			}
+
+		} else if (!strcmp(argv[i], "-paper_loaded")) {
+			if (set_printer_status(PRINTER_PAPER_EMPTY, 1)) {
+				retval = 1;
+			}
+
+		} else if (!strcmp(argv[i], "-paper_out")) {
+			if (set_printer_status(PRINTER_PAPER_EMPTY, 0)) {
+				retval = 1;
+			}
+
+		} else if (!strcmp(argv[i], "-selected")) {
+			if (set_printer_status(PRINTER_SELECTED, 0)) {
+				retval = 1;
+			}
+
+		} else if (!strcmp(argv[i], "-not_selected")) {
+			if (set_printer_status(PRINTER_SELECTED, 1)) {
+				retval = 1;
+			}
+
+		} else if (!strcmp(argv[i], "-error")) {
+			if (set_printer_status(PRINTER_NOT_ERROR, 1)) {
+				retval = 1;
+			}
+
+		} else if (!strcmp(argv[i], "-no_error")) {
+			if (set_printer_status(PRINTER_NOT_ERROR, 0)) {
+				retval = 1;
+			}
+
+		} else if (!strcmp(argv[i], "-read_data")) {
+			if (read_printer_data()) {
+				retval = 1;
+			}
+
+		} else if (!strcmp(argv[i], "-write_data")) {
+			if (write_printer_data()) {
+				retval = 1;
+			}
+
+		} else if (!strcmp(argv[i], "-NB_read_data")) {
+			if (read_NB_printer_data()) {
+				retval = 1;
+			}
+
+		} else {
+			usage(argv[i]);
+			retval = 1;
+		}
+	}
+
+	exit(retval);
+}

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
 

drivers/usb/gadget/printer.c

+/*
+ * printer.c -- Printer gadget driver
+ *
+ * Copyright (C) 2003-2005 David Brownell
+ * Copyright (C) 2006 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
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/ioport.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/smp_lock.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/timer.h>
+#include <linux/list.h>
+#include <linux/interrupt.h>
+#include <linux/utsname.h>
+#include <linux/device.h>
+#include <linux/moduleparam.h>
+#include <linux/fs.h>
+#include <linux/poll.h>
+#include <linux/types.h>
+#include <linux/ctype.h>
+#include <linux/cdev.h>
+
+#include <asm/byteorder.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <asm/system.h>
+#include <linux/uaccess.h>
+#include <asm/unaligned.h>
+
+#include <linux/usb/ch9.h>
+#include <linux/usb/gadget.h>
+#include <linux/usb/g_printer.h>
+
+#include "gadget_chips.h"
+
+#define DRIVER_DESC		"Printer Gadget"
+#define DRIVER_VERSION		"2007 OCT 06"
+
+static const char shortname [] = "printer";
+static const char driver_desc [] = DRIVER_DESC;
+
+static dev_t g_printer_devno;
+
+static struct class *usb_gadget_class;
+
+/*-------------------------------------------------------------------------*/
+
+struct printer_dev {
+	spinlock_t		lock;		/* lock this structure */
+	/* lock buffer lists during read/write calls */
+	spinlock_t		lock_printer_io;
+	struct usb_gadget	*gadget;
+	struct usb_request	*req;		/* for control responses */
+	u8			config;
+	s8			interface;
+	struct usb_ep		*in_ep, *out_ep;
+	const struct usb_endpoint_descriptor
+				*in, *out;
+	struct list_head	rx_reqs;	/* List of free RX structs */
+	struct list_head	rx_reqs_active;	/* List of Active RX xfers */
+	struct list_head	rx_buffers;	/* List of completed xfers */
+	/* wait until there is data to be read. */
+	wait_queue_head_t	rx_wait;
+	struct list_head	tx_reqs;	/* List of free TX structs */
+	struct list_head	tx_reqs_active; /* List of Active TX xfers */
+	/* Wait until there are write buffers available to use. */
+	wait_queue_head_t	tx_wait;
+	/* Wait until all write buffers have been sent. */
+	wait_queue_head_t	tx_flush_wait;
+	struct usb_request	*current_rx_req;
+	size_t			current_rx_bytes;
+	u8			*current_rx_buf;
+	u8			printer_status;
+	u8			reset_printer;
+	struct class_device	*printer_class_dev;
+	struct cdev		printer_cdev;
+	struct device		*pdev;
+	u8			printer_cdev_open;
+	wait_queue_head_t	wait;
+};
+
+static struct printer_dev usb_printer_gadget;
+
+/*-------------------------------------------------------------------------*/
+
+/* DO NOT REUSE THESE IDs with a protocol-incompatible driver!!  Ever!!
+ * Instead:  allocate your own, using normal USB-IF procedures.
+ */
+
+/* Thanks to NetChip Technologies for donating this product ID.
+ */
+#define PRINTER_VENDOR_NUM	0x0525		/* NetChip */
+#define PRINTER_PRODUCT_NUM	0xa4a8		/* Linux-USB Printer Gadget */
+
+/* Some systems will want different product identifers published in the
+ * device descriptor, either numbers or strings or both.  These string
+ * parameters are in UTF-8 (superset of ASCII's 7 bit characters).
+ */
+
+static ushort __initdata idVendor;
+module_param(idVendor, ushort, S_IRUGO);
+MODULE_PARM_DESC(idVendor, "USB Vendor ID");
+
+static ushort __initdata idProduct;
+module_param(idProduct, ushort, S_IRUGO);
+MODULE_PARM_DESC(idProduct, "USB Product ID");
+
+static ushort __initdata bcdDevice;
+module_param(bcdDevice, ushort, S_IRUGO);
+MODULE_PARM_DESC(bcdDevice, "USB Device version (BCD)");
+
+static char *__initdata iManufacturer;
+module_param(iManufacturer, charp, S_IRUGO);
+MODULE_PARM_DESC(iManufacturer, "USB Manufacturer string");
+
+static char *__initdata iProduct;
+module_param(iProduct, charp, S_IRUGO);
+MODULE_PARM_DESC(iProduct, "USB Product string");
+
+static char *__initdata iSerialNum;
+module_param(iSerialNum, charp, S_IRUGO);
+MODULE_PARM_DESC(iSerialNum, "1");
+
+static char *__initdata iPNPstring;
+module_param(iPNPstring, charp, S_IRUGO);
+MODULE_PARM_DESC(iPNPstring, "MFG:linux;MDL:g_printer;CLS:PRINTER;SN:1;");
+
+/* Number of requests to allocate per endpoint, not used for ep0. */
+static unsigned qlen = 10;
+module_param(qlen, uint, S_IRUGO|S_IWUSR);
+
+#define QLEN	qlen
+
+#ifdef CONFIG_USB_GADGET_DUALSPEED
+#define DEVSPEED	USB_SPEED_HIGH
+#else   /* full speed (low speed doesn't do bulk) */
+#define DEVSPEED        USB_SPEED_FULL
+#endif
+
+/*-------------------------------------------------------------------------*/
+
+#define xprintk(d, level, fmt, args...) \
+	printk(level "%s: " fmt, DRIVER_DESC, ## args)
+
+#ifdef DEBUG
+#define DBG(dev, fmt, args...) \
+	xprintk(dev, KERN_DEBUG, fmt, ## args)
+#else
+#define DBG(dev, fmt, args...) \
+	do { } while (0)
+#endif /* DEBUG */
+
+#ifdef VERBOSE
+#define VDBG(dev, fmt, args...) \
+	xprintk(dev, KERN_DEBUG, fmt, ## args)
+#else
+#define VDBG(dev, fmt, args...) \
+	do { } while (0)
+#endif /* VERBOSE */
+
+#define ERROR(dev, fmt, args...) \
+	xprintk(dev, KERN_ERR, fmt, ## args)
+#define WARN(dev, fmt, args...) \
+	xprintk(dev, KERN_WARNING, fmt, ## args)
+#define INFO(dev, fmt, args...) \
+	xprintk(dev, KERN_INFO, fmt, ## args)
+
+/*-------------------------------------------------------------------------*/
+
+/* USB DRIVER HOOKUP (to the hardware driver, below us), mostly
+ * ep0 implementation:  descriptors, config management, setup().
+ * also optional class-specific notification interrupt transfer.
+ */
+
+/*
+ * DESCRIPTORS ... most are static, but strings and (full) configuration
+ * descriptors are built on demand.
+ */
+
+#define STRING_MANUFACTURER		1
+#define STRING_PRODUCT			2
+#define STRING_SERIALNUM		3
+
+/* holds our biggest descriptor */
+#define USB_DESC_BUFSIZE		256
+#define USB_BUFSIZE			8192
+
+/* This device advertises one configuration. */
+#define DEV_CONFIG_VALUE		1
+#define	PRINTER_INTERFACE		0
+
+static struct usb_device_descriptor device_desc = {
+	.bLength =		sizeof device_desc,
+	.bDescriptorType =	USB_DT_DEVICE,
+	.bcdUSB =		__constant_cpu_to_le16(0x0200),
+	.bDeviceClass =		USB_CLASS_PER_INTERFACE,
+	.bDeviceSubClass =	0,
+	.bDeviceProtocol =	0,
+	.idVendor =		__constant_cpu_to_le16(PRINTER_VENDOR_NUM),
+	.idProduct =		__constant_cpu_to_le16(PRINTER_PRODUCT_NUM),
+	.iManufacturer =	STRING_MANUFACTURER,
+	.iProduct =		STRING_PRODUCT,
+	.iSerialNumber =	STRING_SERIALNUM,
+	.bNumConfigurations =	1
+};
+
+static struct usb_otg_descriptor otg_desc = {
+	.bLength =		sizeof otg_desc,
+	.bDescriptorType =	USB_DT_OTG,
+	.bmAttributes =		USB_OTG_SRP
+};
+
+static struct usb_config_descriptor config_desc = {
+	.bLength =		sizeof config_desc,
+	.bDescriptorType =	USB_DT_CONFIG,
+
+	/* compute wTotalLength on the fly */
+	.bNumInterfaces =	1,
+	.bConfigurationValue =	DEV_CONFIG_VALUE,
+	.iConfiguration =	0,
+	.bmAttributes =		USB_CONFIG_ATT_ONE | USB_CONFIG_ATT_SELFPOWER,
+	.bMaxPower =		1	/* Self-Powered */
+};
+
+static struct usb_interface_descriptor intf_desc = {
+	.bLength =		sizeof intf_desc,
+	.bDescriptorType =	USB_DT_INTERFACE,
+	.bInterfaceNumber =	PRINTER_INTERFACE,
+	.bNumEndpoints =	2,
+	.bInterfaceClass =	USB_CLASS_PRINTER,
+	.bInterfaceSubClass =	1,	/* Printer Sub-Class */
+	.bInterfaceProtocol =	2,	/* Bi-Directional */
+	.iInterface =		0
+};
+
+static struct usb_endpoint_descriptor fs_ep_in_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK
+};
+
+static struct usb_endpoint_descriptor fs_ep_out_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bEndpointAddress =	USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK
+};
+
+static const struct usb_descriptor_header *fs_printer_function [11] = {
+	(struct usb_descriptor_header *) &otg_desc,
+	(struct usb_descriptor_header *) &intf_desc,
+	(struct usb_descriptor_header *) &fs_ep_in_desc,
+	(struct usb_descriptor_header *) &fs_ep_out_desc,
+	NULL
+};
+
+#ifdef	CONFIG_USB_GADGET_DUALSPEED
+
+/*
+ * usb 2.0 devices need to expose both high speed and full speed
+ * descriptors, unless they only run at full speed.
+ */
+
+static struct usb_endpoint_descriptor hs_ep_in_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	__constant_cpu_to_le16(512)
+};
+
+static struct usb_endpoint_descriptor hs_ep_out_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	__constant_cpu_to_le16(512)
+};
+
+static struct usb_qualifier_descriptor dev_qualifier = {
+	.bLength =		sizeof dev_qualifier,
+	.bDescriptorType =	USB_DT_DEVICE_QUALIFIER,
+	.bcdUSB =		__constant_cpu_to_le16(0x0200),
+	.bDeviceClass =		USB_CLASS_PRINTER,
+	.bNumConfigurations =	1
+};
+
+static const struct usb_descriptor_header *hs_printer_function [11] = {
+	(struct usb_descriptor_header *) &otg_desc,
+	(struct usb_descriptor_header *) &intf_desc,
+	(struct usb_descriptor_header *) &hs_ep_in_desc,
+	(struct usb_descriptor_header *) &hs_ep_out_desc,
+	NULL
+};
+
+/* maxpacket and other transfer characteristics vary by speed. */
+#define ep_desc(g, hs, fs) (((g)->speed == USB_SPEED_HIGH)?(hs):(fs))
+
+#else
+
+/* if there's no high speed support, maxpacket doesn't change. */
+#define ep_desc(g, hs, fs) (((void)(g)), (fs))
+
+#endif	/* !CONFIG_USB_GADGET_DUALSPEED */
+
+/*-------------------------------------------------------------------------*/
+
+/* descriptors that are built on-demand */
+
+static char				manufacturer [50];
+static char				product_desc [40] = DRIVER_DESC;
+static char				serial_num [40] = "1";
+static char				pnp_string [1024] =
+	"XXMFG:linux;MDL:g_printer;CLS:PRINTER;SN:1;";
+
+/* static strings, in UTF-8 */
+static struct usb_string		strings [] = {
+	{ STRING_MANUFACTURER,	manufacturer, },
+	{ STRING_PRODUCT,	product_desc, },
+	{ STRING_SERIALNUM,	serial_num, },
+	{  }		/* end of list */
+};
+
+static struct usb_gadget_strings	stringtab = {
+	.language	= 0x0409,	/* en-us */
+	.strings	= strings,
+};
+
+/*-------------------------------------------------------------------------*/
+
+static struct usb_request *
+printer_req_alloc(struct usb_ep *ep, unsigned len, gfp_t gfp_flags)
+{
+	struct usb_request	*req;
+
+	req = usb_ep_alloc_request(ep, gfp_flags);
+
+	if (req != NULL) {
+		req->length = len;
+		req->buf = kmalloc(len, gfp_flags);
+		if (req->buf == NULL) {
+			usb_ep_free_request(ep, req);
+			return NULL;
+		}
+	}
+
+	return req;
+}
+
+static void
+printer_req_free(struct usb_ep *ep, struct usb_request *req)
+{
+	if (ep != NULL && req != NULL) {
+		kfree(req->buf);
+		usb_ep_free_request(ep, req);
+	}
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void rx_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct printer_dev	*dev = ep->driver_data;
+	int			status = req->status;
+	unsigned long		flags;
+
+	spin_lock_irqsave(&dev->lock, flags);
+
+	list_del_init(&req->list);	/* Remode from Active List */
+
+	switch (status) {
+
+	/* normal completion */
+	case 0:
+		list_add_tail(&req->list, &dev->rx_buffers);
+		wake_up_interruptible(&dev->rx_wait);
+		DBG(dev, "G_Printer : rx length %d\n", req->actual);
+		break;
+
+	/* software-driven interface shutdown */
+	case -ECONNRESET:		/* unlink */
+	case -ESHUTDOWN:		/* disconnect etc */
+		VDBG(dev, "rx shutdown, code %d\n", status);
+		list_add(&req->list, &dev->rx_reqs);
+		break;
+
+	/* for hardware automagic (such as pxa) */
+	case -ECONNABORTED:		/* endpoint reset */
+		DBG(dev, "rx %s reset\n", ep->name);
+		list_add(&req->list, &dev->rx_reqs);
+		break;
+
+	/* data overrun */
+	case -EOVERFLOW:
+		/* FALLTHROUGH */
+
+	default:
+		DBG(dev, "rx status %d\n", status);
+		list_add(&req->list, &dev->rx_reqs);
+		break;
+	}
+	spin_unlock_irqrestore(&dev->lock, flags);
+}
+
+static void tx_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct printer_dev	*dev = ep->driver_data;
+
+	switch (req->status) {
+	default:
+		VDBG(dev, "tx err %d\n", req->status);
+		/* FALLTHROUGH */
+	case -ECONNRESET:		/* unlink */
+	case -ESHUTDOWN:		/* disconnect etc */
+		break;
+	case 0:
+		break;
+	}
+
+	spin_lock(&dev->lock);
+	/* Take the request struct off the active list and put it on the
+	 * free list.
+	 */
+	list_del_init(&req->list);
+	list_add(&req->list, &dev->tx_reqs);
+	wake_up_interruptible(&dev->tx_wait);
+	if (likely(list_empty(&dev->tx_reqs_active)))
+		wake_up_interruptible(&dev->tx_flush_wait);
+
+	spin_unlock(&dev->lock);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int
+printer_open(struct inode *inode, struct file *fd)
+{
+	struct printer_dev	*dev;
+	unsigned long		flags;
+	int			ret = -EBUSY;
+
+	dev = container_of(inode->i_cdev, struct printer_dev, printer_cdev);
+
+	spin_lock_irqsave(&dev->lock, flags);
+
+	if (!dev->printer_cdev_open) {
+		dev->printer_cdev_open = 1;
+		fd->private_data = dev;
+		ret = 0;
+		/* Change the printer status to show that it's on-line. */
+		dev->printer_status |= PRINTER_SELECTED;
+	}
+
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	DBG(dev, "printer_open returned %x\n", ret);
+
+	return ret;
+}
+
+static int
+printer_close(struct inode *inode, struct file *fd)
+{
+	struct printer_dev	*dev = fd->private_data;
+	unsigned long		flags;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	dev->printer_cdev_open = 0;
+	fd->private_data = NULL;
+	/* Change printer status to show that the printer is off-line. */
+	dev->printer_status &= ~PRINTER_SELECTED;
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	DBG(dev, "printer_close\n");
+
+	return 0;
+}
+
+static ssize_t
+printer_read(struct file *fd, char __user *buf, size_t len, loff_t *ptr)
+{
+	struct printer_dev		*dev = fd->private_data;
+	unsigned long			flags;
+	size_t				size;
+	size_t				bytes_copied;
+	struct usb_request		*req;
+	/* This is a pointer to the current USB rx request. */
+	struct usb_request		*current_rx_req;
+	/* This is the number of bytes in the current rx buffer. */
+	size_t				current_rx_bytes;
+	/* This is a pointer to the current rx buffer. */
+	u8				*current_rx_buf;
+
+	if (len == 0)
+		return -EINVAL;
+
+	DBG(dev, "printer_read trying to read %d bytes\n", (int)len);
+
+	spin_lock(&dev->lock_printer_io);
+	spin_lock_irqsave(&dev->lock, flags);
+
+	/* We will use this flag later to check if a printer reset happened
+	 * after we turn interrupts back on.
+	 */
+	dev->reset_printer = 0;
+
+	while (likely(!list_empty(&dev->rx_reqs))) {
+		int error;
+
+		req = container_of(dev->rx_reqs.next,
+				struct usb_request, list);
+		list_del_init(&req->list);
+
+		/* The USB Host sends us whatever amount of data it wants to
+		 * so we always set the length field to the full USB_BUFSIZE.
+		 * If the amount of data is more than the read() caller asked
+		 * for it will be stored in the request buffer until it is
+		 * asked for by read().
+		 */
+		req->length = USB_BUFSIZE;
+		req->complete = rx_complete;
+
+		error = usb_ep_queue(dev->out_ep, req, GFP_ATOMIC);
+		if (error) {
+			DBG(dev, "rx submit --> %d\n", error);
+			list_add(&req->list, &dev->rx_reqs);
+			break;
+		} else {
+			list_add(&req->list, &dev->rx_reqs_active);
+		}
+	}
+
+	bytes_copied = 0;
+	current_rx_req = dev->current_rx_req;
+	current_rx_bytes = dev->current_rx_bytes;
+	current_rx_buf = dev->current_rx_buf;
+	dev->current_rx_req = NULL;
+	dev->current_rx_bytes = 0;
+	dev->current_rx_buf = NULL;
+
+	/* Check if there is any data in the read buffers. Please note that
+	 * current_rx_bytes is the number of bytes in the current rx buffer.
+	 * If it is zero then check if there are any other rx_buffers that
+	 * are on the completed list. We are only out of data if all rx
+	 * buffers are empty.
+	 */
+	if ((current_rx_bytes == 0) &&
+			(likely(list_empty(&dev->rx_buffers)))) {
+		/* Turn interrupts back on before sleeping. */
+		spin_unlock_irqrestore(&dev->lock, flags);
+
+		/*
+		 * If no data is available check if this is a NON-Blocking
+		 * call or not.
+		 */
+		if (fd->f_flags & (O_NONBLOCK|O_NDELAY)) {
+			spin_unlock(&dev->lock_printer_io);
+			return -EAGAIN;
+		}
+
+		/* Sleep until data is available */
+		wait_event_interruptible(dev->rx_wait,
+				(likely(!list_empty(&dev->rx_buffers))));
+		spin_lock_irqsave(&dev->lock, flags);
+	}
+
+	/* We have data to return then copy it to the caller's buffer.*/
+	while ((current_rx_bytes || likely(!list_empty(&dev->rx_buffers)))
+			&& len) {
+		if (current_rx_bytes == 0) {
+			req = container_of(dev->rx_buffers.next,
+					struct usb_request, list);
+			list_del_init(&req->list);
+
+			if (req->actual && req->buf) {
+				current_rx_req = req;
+				current_rx_bytes = req->actual;
+				current_rx_buf = req->buf;
+			} else {
+				list_add(&req->list, &dev->rx_reqs);
+				continue;
+			}
+		}
+
+		/* Don't leave irqs off while doing memory copies */
+		spin_unlock_irqrestore(&dev->lock, flags);
+
+		if (len > current_rx_bytes)
+			size = current_rx_bytes;
+		else
+			size = len;
+
+		size -= copy_to_user(buf, current_rx_buf, size);
+		bytes_copied += size;
+		len -= size;
+		buf += size;
+
+		spin_lock_irqsave(&dev->lock, flags);
+
+		/* We've disconnected or reset free the req and buffer */
+		if (dev->reset_printer) {
+			printer_req_free(dev->out_ep, current_rx_req);
+			spin_unlock_irqrestore(&dev->lock, flags);
+			spin_unlock(&dev->lock_printer_io);
+			return -EAGAIN;
+		}
+
+		/* If we not returning all the data left in this RX request
+		 * buffer then adjust the amount of data left in the buffer.
+		 * Othewise if we are done with this RX request buffer then
+		 * requeue it to get any incoming data from the USB host.
+		 */
+		if (size < current_rx_bytes) {
+			current_rx_bytes -= size;
+			current_rx_buf += size;
+		} else {
+			list_add(&current_rx_req->list, &dev->rx_reqs);
+			current_rx_bytes = 0;
+			current_rx_buf = NULL;
+			current_rx_req = NULL;
+		}
+	}
+
+	dev->current_rx_req = current_rx_req;
+	dev->current_rx_bytes = current_rx_bytes;
+	dev->current_rx_buf = current_rx_buf;
+
+	spin_unlock_irqrestore(&dev->lock, flags);
+	spin_unlock(&dev->lock_printer_io);
+
+	DBG(dev, "printer_read returned %d bytes\n", (int)bytes_copied);
+
+	if (bytes_copied)
+		return bytes_copied;
+	else
+		return -EAGAIN;
+}
+
+static ssize_t
+printer_write(struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
+{
+	struct printer_dev	*dev = fd->private_data;
+	unsigned long		flags;
+	size_t			size;	/* Amount of data in a TX request. */
+	size_t			bytes_copied = 0;
+	struct usb_request	*req;
+
+	DBG(dev, "printer_write trying to send %d bytes\n", (int)len);
+
+	if (len == 0)
+		return -EINVAL;
+
+	spin_lock(&dev->lock_printer_io);
+	spin_lock_irqsave(&dev->lock, flags);
+
+	/* Check if a printer reset happens while we have interrupts on */
+	dev->reset_printer = 0;
+
+	/* Check if there is any available write buffers */
+	if (likely(list_empty(&dev->tx_reqs))) {
+		/* Turn interrupts back on before sleeping. */
+		spin_unlock_irqrestore(&dev->lock, flags);
+
+		/*
+		 * If write buffers are available check if this is
+		 * a NON-Blocking call or not.
+		 */
+		if (fd->f_flags & (O_NONBLOCK|O_NDELAY)) {
+			spin_unlock(&dev->lock_printer_io);
+			return -EAGAIN;
+		}
+
+		/* Sleep until a write buffer is available */
+		wait_event_interruptible(dev->tx_wait,
+				(likely(!list_empty(&dev->tx_reqs))));
+		spin_lock_irqsave(&dev->lock, flags);
+	}
+
+	while (likely(!list_empty(&dev->tx_reqs)) && len) {
+
+		if (len > USB_BUFSIZE)
+			size = USB_BUFSIZE;
+		else
+			size = len;
+
+		req = container_of(dev->tx_reqs.next, struct usb_request,
+				list);
+		list_del_init(&req->list);
+
+		req->complete = tx_complete;
+		req->length = size;
+
+		/* Check if we need to send a zero length packet. */
+		if (len > size)
+			/* They will be more TX requests so no yet. */
+			req->zero = 0;
+		else
+			/* If the data amount is not a multple of the
+			 * maxpacket size then send a zero length packet.
+			 */
+			req->zero = ((len % dev->in_ep->maxpacket) == 0);
+
+		/* Don't leave irqs off while doing memory copies */
+		spin_unlock_irqrestore(&dev->lock, flags);
+
+		if (copy_from_user(req->buf, buf, size)) {
+			list_add(&req->list, &dev->tx_reqs);
+			spin_unlock(&dev->lock_printer_io);
+			return bytes_copied;
+		}
+
+		bytes_copied += size;
+		len -= size;
+		buf += size;
+
+		spin_lock_irqsave(&dev->lock, flags);
+
+		/* We've disconnected or reset so free the req and buffer */
+		if (dev->reset_printer) {
+			printer_req_free(dev->in_ep, req);
+			spin_unlock_irqrestore(&dev->lock, flags);
+			spin_unlock(&dev->lock_printer_io);
+			return -EAGAIN;
+		}
+
+		if (usb_ep_queue(dev->in_ep, req, GFP_ATOMIC)) {
+			list_add(&req->list, &dev->tx_reqs);
+			spin_unlock_irqrestore(&dev->lock, flags);
+			spin_unlock(&dev->lock_printer_io);
+			return -EAGAIN;
+		}
+
+		list_add(&req->list, &dev->tx_reqs_active);
+
+	}
+
+	spin_unlock_irqrestore(&dev->lock, flags);
+	spin_unlock(&dev->lock_printer_io);
+
+	DBG(dev, "printer_write sent %d bytes\n", (int)bytes_copied);
+
+	if (bytes_copied) {
+		return bytes_copied;
+	} else {
+		return -EAGAIN;
+	}
+}
+
+static int
+printer_fsync(struct file *fd, struct dentry *dentry, int datasync)
+{
+	struct printer_dev	*dev = fd->private_data;
+	unsigned long		flags;
+	int			tx_list_empty;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	tx_list_empty = (likely(list_empty(&dev->tx_reqs)));
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	if (!tx_list_empty) {
+		/* Sleep until all data has been sent */
+		wait_event_interruptible(dev->tx_flush_wait,
+				(likely(list_empty(&dev->tx_reqs_active))));
+	}
+
+	return 0;
+}
+
+static unsigned int
+printer_poll(struct file *fd, poll_table *wait)
+{
+	struct printer_dev	*dev = fd->private_data;
+	unsigned long		flags;
+	int			status = 0;
+
+	poll_wait(fd, &dev->rx_wait, wait);
+	poll_wait(fd, &dev->tx_wait, wait);
+
+	spin_lock_irqsave(&dev->lock, flags);
+	if (likely(!list_empty(&dev->tx_reqs)))
+		status |= POLLOUT | POLLWRNORM;
+
+	if (likely(!list_empty(&dev->rx_buffers)))
+		status |= POLLIN | POLLRDNORM;
+
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	return status;
+}
+
+static int
+printer_ioctl(struct inode *inode, struct file *fd, unsigned int code,
+		unsigned long arg)
+{
+	struct printer_dev	*dev = fd->private_data;
+	unsigned long		flags;
+	int			status = 0;
+
+	DBG(dev, "printer_ioctl: cmd=0x%4.4x, arg=%lu\n", code, arg);
+
+	/* handle ioctls */
+
+	spin_lock_irqsave(&dev->lock, flags);
+
+	switch (code) {
+	case GADGET_GET_PRINTER_STATUS:
+		status = (int)dev->printer_status;
+		break;
+	case GADGET_SET_PRINTER_STATUS:
+		dev->printer_status = (u8)arg;
+		break;
+	default:
+		/* could not handle ioctl */
+		DBG(dev, "printer_ioctl: ERROR cmd=0x%4.4xis not supported\n",
+				code);
+		status = -ENOTTY;
+	}
+
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	return status;
+}
+
+/* used after endpoint configuration */
+static struct file_operations printer_io_operations = {
+	.owner =	THIS_MODULE,
+	.open =		printer_open,
+	.read =		printer_read,
+	.write =	printer_write,
+	.fsync =	printer_fsync,
+	.poll =		printer_poll,
+	.ioctl =	printer_ioctl,
+	.release =	printer_close
+};
+
+/*-------------------------------------------------------------------------*/
+
+static int
+set_printer_interface(struct printer_dev *dev)
+{
+	int			result = 0;
+
+	dev->in = ep_desc(dev->gadget, &hs_ep_in_desc, &fs_ep_in_desc);
+	dev->in_ep->driver_data = dev;
+
+	dev->out = ep_desc(dev->gadget, &hs_ep_out_desc, &fs_ep_out_desc);
+	dev->out_ep->driver_data = dev;
+
+	result = usb_ep_enable(dev->in_ep, dev->in);
+	if (result != 0) {
+		DBG(dev, "enable %s --> %d\n", dev->in_ep->name, result);
+		goto done;
+	}
+
+	result = usb_ep_enable(dev->out_ep, dev->out);
+	if (result != 0) {
+		DBG(dev, "enable %s --> %d\n", dev->in_ep->name, result);
+		goto done;
+	}
+
+done:
+	/* on error, disable any endpoints  */
+	if (result != 0) {
+		(void) usb_ep_disable(dev->in_ep);
+		(void) usb_ep_disable(dev->out_ep);
+		dev->in = NULL;
+		dev->out = NULL;
+	}
+
+	/* caller is responsible for cleanup on error */
+	return result;
+}
+
+static void printer_reset_interface(struct printer_dev *dev)
+{
+	if (dev->interface < 0)
+		return;
+
+	DBG(dev, "%s\n", __FUNCTION__);
+
+	if (dev->in)
+		usb_ep_disable(dev->in_ep);
+
+	if (dev->out)
+		usb_ep_disable(dev->out_ep);
+
+	dev->interface = -1;
+}
+
+/* change our operational config.  must agree with the code
+ * that returns config descriptors, and altsetting code.
+ */
+static int
+printer_set_config(struct printer_dev *dev, unsigned number)
+{
+	int			result = 0;
+	struct usb_gadget	*gadget = dev->gadget;
+
+	if (gadget_is_sa1100(gadget) && dev->config) {
+		/* tx fifo is full, but we can't clear it...*/
+		INFO(dev, "can't change configurations\n");
+		return -ESPIPE;
+	}
+
+	switch (number) {
+	case DEV_CONFIG_VALUE:
+		result = 0;
+		break;
+	default:
+		result = -EINVAL;
+		/* FALL THROUGH */
+	case 0:
+		break;
+	}
+
+	if (result) {
+		usb_gadget_vbus_draw(dev->gadget,
+				dev->gadget->is_otg ? 8 : 100);
+	} else {
+		char *speed;
+		unsigned power;
+
+		power = 2 * config_desc.bMaxPower;
+		usb_gadget_vbus_draw(dev->gadget, power);
+
+		switch (gadget->speed) {
+		case USB_SPEED_FULL:	speed = "full"; break;
+#ifdef CONFIG_USB_GADGET_DUALSPEED
+		case USB_SPEED_HIGH:	speed = "high"; break;
+#endif
+		default:		speed = "?"; break;
+		}
+
+		dev->config = number;
+		INFO(dev, "%s speed config #%d: %d mA, %s\n",
+				speed, number, power, driver_desc);
+	}
+	return result;
+}
+
+static int
+config_buf(enum usb_device_speed speed, u8 *buf, u8 type, unsigned index,
+		int is_otg)
+{
+	int					len;
+	const struct usb_descriptor_header	**function;
+#ifdef CONFIG_USB_GADGET_DUALSPEED
+	int					hs = (speed == USB_SPEED_HIGH);
+
+	if (type == USB_DT_OTHER_SPEED_CONFIG)
+		hs = !hs;
+
+	if (hs) {
+		function = hs_printer_function;
+	} else {
+		function = fs_printer_function;
+	}
+#else
+	function = fs_printer_function;
+#endif
+
+	if (index >= device_desc.bNumConfigurations)
+		return -EINVAL;
+
+	/* for now, don't advertise srp-only devices */
+	if (!is_otg)
+		function++;
+
+	len = usb_gadget_config_buf(&config_desc, buf, USB_DESC_BUFSIZE,
+			function);
+	if (len < 0)
+		return len;
+	((struct usb_config_descriptor *) buf)->bDescriptorType = type;
+	return len;
+}
+
+/* Change our operational Interface. */
+static int
+set_interface(struct printer_dev *dev, unsigned number)
+{
+	int			result = 0;
+
+	if (gadget_is_sa1100(dev->gadget) && dev->interface < 0) {
+		/* tx fifo is full, but we can't clear it...*/
+		INFO(dev, "can't change interfaces\n");
+		return -ESPIPE;
+	}
+
+	/* Free the current interface */
+	switch (dev->interface) {
+	case PRINTER_INTERFACE:
+		printer_reset_interface(dev);
+		break;
+	}
+
+	switch (number) {
+	case PRINTER_INTERFACE:
+		result = set_printer_interface(dev);
+		if (result) {
+			printer_reset_interface(dev);
+		} else {
+			dev->interface = PRINTER_INTERFACE;
+		}
+		break;
+	default:
+		result = -EINVAL;
+		/* FALL THROUGH */
+	}
+
+	if (!result)
+		INFO(dev, "Using interface %x\n", number);
+
+	return result;
+}
+
+static void printer_setup_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	if (req->status || req->actual != req->length)
+		DBG((struct printer_dev *) ep->driver_data,
+				"setup complete --> %d, %d/%d\n",
+				req->status, req->actual, req->length);
+}
+
+static void printer_soft_reset(struct printer_dev *dev)
+{
+	struct usb_request	*req;
+
+	INFO(dev, "Received Printer Reset Request\n");
+
+	if (usb_ep_disable(dev->in_ep))
+		DBG(dev, "Failed to disable USB in_ep\n");
+	if (usb_ep_disable(dev->out_ep))
+		DBG(dev, "Failed to disable USB out_ep\n");
+
+	if (dev->current_rx_req != NULL) {
+		list_add(&dev->current_rx_req->list, &dev->rx_reqs);
+		dev->current_rx_req = NULL;
+	}
+	dev->current_rx_bytes = 0;
+	dev->current_rx_buf = NULL;
+	dev->reset_printer = 1;
+
+	while (likely(!(list_empty(&dev->rx_buffers)))) {
+		req = container_of(dev->rx_buffers.next, struct usb_request,
+				list);
+		list_del_init(&req->list);
+		list_add(&req->list, &dev->rx_reqs);
+	}
+
+	while (likely(!(list_empty(&dev->rx_reqs_active)))) {
+		req = container_of(dev->rx_buffers.next, struct usb_request,
+				list);
+		list_del_init(&req->list);
+		list_add(&req->list, &dev->rx_reqs);
+	}
+
+	while (likely(!(list_empty(&dev->tx_reqs_active)))) {
+		req = container_of(dev->tx_reqs_active.next,
+				struct usb_request, list);
+		list_del_init(&req->list);
+		list_add(&req->list, &dev->tx_reqs);
+	}
+
+	if (usb_ep_enable(dev->in_ep, dev->in))
+		DBG(dev, "Failed to enable USB in_ep\n");
+	if (usb_ep_enable(dev->out_ep, dev->out))
+		DBG(dev, "Failed to enable USB out_ep\n");
+
+	wake_up_interruptible(&dev->tx_wait);
+	wake_up_interruptible(&dev->tx_flush_wait);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * The setup() callback implements all the ep0 functionality that's not
+ * handled lower down.
+ */
+static int
+printer_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
+{
+	struct printer_dev	*dev = get_gadget_data(gadget);
+	struct usb_request	*req = dev->req;
+	int			value = -EOPNOTSUPP;
+	u16			wIndex = le16_to_cpu(ctrl->wIndex);
+	u16			wValue = le16_to_cpu(ctrl->wValue);
+	u16			wLength = le16_to_cpu(ctrl->wLength);
+
+	DBG(dev, "ctrl req%02x.%02x v%04x i%04x l%d\n",
+		ctrl->bRequestType, ctrl->bRequest, wValue, wIndex, wLength);
+
+	req->complete = printer_setup_complete;
+
+	switch (ctrl->bRequestType&USB_TYPE_MASK) {
+
+	case USB_TYPE_STANDARD:
+		switch (ctrl->bRequest) {
+
+		case USB_REQ_GET_DESCRIPTOR:
+			if (ctrl->bRequestType != USB_DIR_IN)
+				break;
+			switch (wValue >> 8) {
+
+			case USB_DT_DEVICE:
+				value = min(wLength, (u16) sizeof device_desc);
+				memcpy(req->buf, &device_desc, value);
+				break;
+#ifdef CONFIG_USB_GADGET_DUALSPEED
+			case USB_DT_DEVICE_QUALIFIER:
+				if (!gadget->is_dualspeed)
+					break;
+				value = min(wLength,
+						(u16) sizeof dev_qualifier);
+				memcpy(req->buf, &dev_qualifier, value);
+				break;
+
+			case USB_DT_OTHER_SPEED_CONFIG:
+				if (!gadget->is_dualspeed)
+					break;
+				/* FALLTHROUGH */
+#endif /* CONFIG_USB_GADGET_DUALSPEED */
+			case USB_DT_CONFIG:
+				value = config_buf(gadget->speed, req->buf,
+						wValue >> 8,
+						wValue & 0xff,
+						gadget->is_otg);
+				if (value >= 0)
+					value = min(wLength, (u16) value);
+				break;
+
+			case USB_DT_STRING:
+				value = usb_gadget_get_string(&stringtab,
+						wValue & 0xff, req->buf);
+				if (value >= 0)
+					value = min(wLength, (u16) value);
+				break;
+			}
+			break;
+
+		case USB_REQ_SET_CONFIGURATION:
+			if (ctrl->bRequestType != 0)
+				break;
+			if (gadget->a_hnp_support)
+				DBG(dev, "HNP available\n");
+			else if (gadget->a_alt_hnp_support)
+				DBG(dev, "HNP needs a different root port\n");
+			value = printer_set_config(dev, wValue);
+			break;
+		case USB_REQ_GET_CONFIGURATION:
+			if (ctrl->bRequestType != USB_DIR_IN)
+				break;
+			*(u8 *)req->buf = dev->config;
+			value = min(wLength, (u16) 1);
+			break;
+
+		case USB_REQ_SET_INTERFACE:
+			if (ctrl->bRequestType != USB_RECIP_INTERFACE ||
+					!dev->config)
+				break;
+
+			value = set_interface(dev, PRINTER_INTERFACE);
+			break;
+		case USB_REQ_GET_INTERFACE:
+			if (ctrl->bRequestType !=
+					(USB_DIR_IN|USB_RECIP_INTERFACE)
+					|| !dev->config)
+				break;
+
+			*(u8 *)req->buf = dev->interface;
+			value = min(wLength, (u16) 1);
+			break;
+
+		default:
+			goto unknown;
+		}
+		break;
+
+	case USB_TYPE_CLASS:
+		switch (ctrl->bRequest) {
+		case 0: /* Get the IEEE-1284 PNP String */
+			/* Only one printer interface is supported. */
+			if ((wIndex>>8) != PRINTER_INTERFACE)
+				break;
+
+			value = (pnp_string[0]<<8)|pnp_string[1];
+			memcpy(req->buf, pnp_string, value);
+			DBG(dev, "1284 PNP String: %x %s\n", value,
+					&pnp_string[2]);
+			break;
+
+		case 1: /* Get Port Status */
+			/* Only one printer interface is supported. */
+			if (wIndex != PRINTER_INTERFACE)
+				break;
+
+			*(u8 *)req->buf = dev->printer_status;
+			value = min(wLength, (u16) 1);
+			break;
+
+		case 2: /* Soft Reset */
+			/* Only one printer interface is supported. */
+			if (wIndex != PRINTER_INTERFACE)
+				break;
+
+			printer_soft_reset(dev);
+
+			value = 0;
+			break;
+
+		default:
+			goto unknown;
+		}
+		break;
+
+	default:
+unknown:
+		VDBG(dev,
+			"unknown ctrl req%02x.%02x v%04x i%04x l%d\n",
+			ctrl->bRequestType, ctrl->bRequest,
+			wValue, wIndex, wLength);
+		break;
+	}
+
+	/* respond with data transfer before status phase? */
+	if (value >= 0) {
+		req->length = value;
+		req->zero = value < wLength
+				&& (value % gadget->ep0->maxpacket) == 0;
+		value = usb_ep_queue(gadget->ep0, req, GFP_ATOMIC);
+		if (value < 0) {
+			DBG(dev, "ep_queue --> %d\n", value);
+			req->status = 0;
+			printer_setup_complete(gadget->ep0, req);
+		}
+	}
+
+	/* host either stalls (value < 0) or reports success */
+	return value;
+}
+
+static void
+printer_disconnect(struct usb_gadget *gadget)
+{
+	struct printer_dev	*dev = get_gadget_data(gadget);
+	unsigned long		flags;
+
+	DBG(dev, "%s\n", __FUNCTION__);
+
+	spin_lock_irqsave(&dev->lock, flags);
+
+	printer_reset_interface(dev);
+
+	spin_unlock_irqrestore(&dev->lock, flags);
+}
+
+static void
+printer_unbind(struct usb_gadget *gadget)
+{
+	struct printer_dev	*dev = get_gadget_data(gadget);
+	struct usb_request	*req;
+
+
+	DBG(dev, "%s\n", __FUNCTION__);
+
+	/* Remove sysfs files */
+	device_destroy(usb_gadget_class, g_printer_devno);
+
+	/* Remove Character Device */
+	cdev_del(&dev->printer_cdev);
+
+	/* we must already have been disconnected ... no i/o may be active */
+	WARN_ON(!list_empty(&dev->tx_reqs_active));
+	WARN_ON(!list_empty(&dev->rx_reqs_active));
+
+	/* Free all memory for this driver. */
+	while (!list_empty(&dev->tx_reqs)) {
+		req = container_of(dev->tx_reqs.next, struct usb_request,
+				list);
+		list_del(&req->list);
+		printer_req_free(dev->in_ep, req);
+	}
+
+	if (dev->current_rx_req != NULL);
+		printer_req_free(dev->out_ep, dev->current_rx_req);
+
+	while (!list_empty(&dev->rx_reqs)) {
+		req = container_of(dev->rx_reqs.next,
+				struct usb_request, list);
+		list_del(&req->list);
+		printer_req_free(dev->out_ep, req);
+	}
+
+	while (!list_empty(&dev->rx_buffers)) {
+		req = container_of(dev->rx_buffers.next,
+				struct usb_request, list);
+		list_del(&req->list);
+		printer_req_free(dev->out_ep, req);
+	}
+
+	if (dev->req) {
+		printer_req_free(gadget->ep0, dev->req);
+		dev->req = NULL;
+	}
+
+	set_gadget_data(gadget, NULL);
+}
+
+static int __init
+printer_bind(struct usb_gadget *gadget)
+{
+	struct printer_dev	*dev;
+	struct usb_ep		*in_ep, *out_ep;
+	int			status = -ENOMEM;
+	int			gcnum;
+	size_t			len;
+	u32			i;
+	struct usb_request	*req;
+
+	dev = &usb_printer_gadget;
+
+
+	/* Setup the sysfs files for the printer gadget. */
+	dev->pdev = device_create(usb_gadget_class, NULL, g_printer_devno,
+			"g_printer");
+	if (IS_ERR(dev->pdev)) {
+		ERROR(dev, "Failed to create device: g_printer\n");
+		goto fail;
+	}
+
+	/*
+	 * Register a character device as an interface to a user mode
+	 * program that handles the printer specific functionality.
+	 */
+	cdev_init(&dev->printer_cdev, &printer_io_operations);
+	dev->printer_cdev.owner = THIS_MODULE;
+	status = cdev_add(&dev->printer_cdev, g_printer_devno, 1);
+	if (status) {
+		ERROR(dev, "Failed to open char device\n");
+		goto fail;
+	}
+
+	if (gadget_is_sa1100(gadget)) {
+		/* hardware can't write zero length packets. */
+		ERROR(dev, "SA1100 controller is unsupport by this driver\n");
+		goto fail;
+	}
+
+	gcnum = usb_gadget_controller_number(gadget);
+	if (gcnum >= 0) {
+		device_desc.bcdDevice = cpu_to_le16(0x0200 + gcnum);
+	} else {
+		dev_warn(&gadget->dev, "controller '%s' not recognized\n",
+			gadget->name);
+		/* unrecognized, but safe unless bulk is REALLY quirky */
+		device_desc.bcdDevice =
+			__constant_cpu_to_le16(0xFFFF);
+	}
+	snprintf(manufacturer, sizeof(manufacturer), "%s %s with %s",
+		init_utsname()->sysname, init_utsname()->release,
+		gadget->name);
+
+	device_desc.idVendor =
+		__constant_cpu_to_le16(PRINTER_VENDOR_NUM);
+	device_desc.idProduct =
+		__constant_cpu_to_le16(PRINTER_PRODUCT_NUM);
+
+	/* support optional vendor/distro customization */
+	if (idVendor) {
+		if (!idProduct) {
+			dev_err(&gadget->dev, "idVendor needs idProduct!\n");
+			return -ENODEV;
+		}
+		device_desc.idVendor = cpu_to_le16(idVendor);
+		device_desc.idProduct = cpu_to_le16(idProduct);
+		if (bcdDevice)
+			device_desc.bcdDevice = cpu_to_le16(bcdDevice);
+	}
+
+	if (iManufacturer)
+		strlcpy(manufacturer, iManufacturer, sizeof manufacturer);
+
+	if (iProduct)
+		strlcpy(product_desc, iProduct, sizeof product_desc);
+
+	if (iSerialNum)
+		strlcpy(serial_num, iSerialNum, sizeof serial_num);
+
+	if (iPNPstring)
+		strlcpy(&pnp_string[2], iPNPstring, (sizeof pnp_string)-2);
+
+	len = strlen(pnp_string);
+	pnp_string[0] = (len >> 8) & 0xFF;
+	pnp_string[1] = len & 0xFF;
+
+	/* all we really need is bulk IN/OUT */
+	usb_ep_autoconfig_reset(gadget);
+	in_ep = usb_ep_autoconfig(gadget, &fs_ep_in_desc);
+	if (!in_ep) {
+autoconf_fail:
+		dev_err(&gadget->dev, "can't autoconfigure on %s\n",
+			gadget->name);
+		return -ENODEV;
+	}
+	in_ep->driver_data = in_ep;	/* claim */
+
+	out_ep = usb_ep_autoconfig(gadget, &fs_ep_out_desc);
+	if (!out_ep)
+		goto autoconf_fail;
+	out_ep->driver_data = out_ep;	/* claim */
+
+#ifdef	CONFIG_USB_GADGET_DUALSPEED
+	/* assumes ep0 uses the same value for both speeds ... */
+	dev_qualifier.bMaxPacketSize0 = device_desc.bMaxPacketSize0;
+
+	/* and that all endpoints are dual-speed */
+	hs_ep_in_desc.bEndpointAddress = fs_ep_in_desc.bEndpointAddress;
+	hs_ep_out_desc.bEndpointAddress = fs_ep_out_desc.bEndpointAddress;
+#endif	/* DUALSPEED */
+
+	device_desc.bMaxPacketSize0 = gadget->ep0->maxpacket;
+	usb_gadget_set_selfpowered(gadget);
+
+	if (gadget->is_otg) {
+		otg_desc.bmAttributes |= USB_OTG_HNP,
+		config_desc.bmAttributes |= USB_CONFIG_ATT_WAKEUP;
+		config_desc.bMaxPower = 4;
+	}
+
+	spin_lock_init(&dev->lock);
+	spin_lock_init(&dev->lock_printer_io);
+	INIT_LIST_HEAD(&dev->tx_reqs);
+	INIT_LIST_HEAD(&dev->tx_reqs_active);
+	INIT_LIST_HEAD(&dev->rx_reqs);
+	INIT_LIST_HEAD(&dev->rx_reqs_active);
+	INIT_LIST_HEAD(&dev->rx_buffers);
+	init_waitqueue_head(&dev->rx_wait);
+	init_waitqueue_head(&dev->tx_wait);
+	init_waitqueue_head(&dev->tx_flush_wait);
+
+	dev->config = 0;
+	dev->interface = -1;
+	dev->printer_cdev_open = 0;
+	dev->printer_status = PRINTER_NOT_ERROR;
+	dev->current_rx_req = NULL;
+	dev->current_rx_bytes = 0;
+	dev->current_rx_buf = NULL;
+
+	dev->in_ep = in_ep;
+	dev->out_ep = out_ep;
+
+	/* preallocate control message data and buffer */
+	dev->req = printer_req_alloc(gadget->ep0, USB_DESC_BUFSIZE,
+			GFP_KERNEL);
+	if (!dev->req) {
+		status = -ENOMEM;
+		goto fail;
+	}
+
+	for (i = 0; i < QLEN; i++) {
+		req = printer_req_alloc(dev->in_ep, USB_BUFSIZE, GFP_KERNEL);
+		if (!req) {
+			while (!list_empty(&dev->tx_reqs)) {
+				req = container_of(dev->tx_reqs.next,
+						struct usb_request, list);
+				list_del(&req->list);
+				printer_req_free(dev->in_ep, req);
+			}
+			return -ENOMEM;
+		}
+		list_add(&req->list, &dev->tx_reqs);
+	}
+
+	for (i = 0; i < QLEN; i++) {
+		req = printer_req_alloc(dev->out_ep, USB_BUFSIZE, GFP_KERNEL);
+		if (!req) {
+			while (!list_empty(&dev->rx_reqs)) {
+				req = container_of(dev->rx_reqs.next,
+						struct usb_request, list);
+				list_del(&req->list);
+				printer_req_free(dev->out_ep, req);
+			}
+			return -ENOMEM;
+		}
+		list_add(&req->list, &dev->rx_reqs);
+	}
+
+	dev->req->complete = printer_setup_complete;
+
+	/* finish hookup to lower layer ... */
+	dev->gadget = gadget;
+	set_gadget_data(gadget, dev);
+	gadget->ep0->driver_data = dev;
+
+	INFO(dev, "%s, version: " DRIVER_VERSION "\n", driver_desc);
+	INFO(dev, "using %s, OUT %s IN %s\n", gadget->name, out_ep->name,
+			in_ep->name);
+
+	return 0;
+
+fail:
+	printer_unbind(gadget);
+	return status;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static struct usb_gadget_driver printer_driver = {
+	.speed		= DEVSPEED,
+
+	.function	= (char *) driver_desc,
+	.bind		= printer_bind,
+	.unbind		= printer_unbind,
+
+	.setup		= printer_setup,
+	.disconnect	= printer_disconnect,
+
+	.driver		= {
+		.name		= (char *) shortname,
+		.owner		= THIS_MODULE,
+	},
+};
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_AUTHOR("Craig Nadler");
+MODULE_LICENSE("GPL");
+
+static int __init
+init(void)
+{
+	int status;
+
+	usb_gadget_class = class_create(THIS_MODULE, "usb_printer_gadget");
+	if (IS_ERR(usb_gadget_class)) {
+		status = PTR_ERR(usb_gadget_class);
+		ERROR(dev, "unable to create usb_gadget class %d\n", status);
+		return status;
+	}
+
+	status = alloc_chrdev_region(&g_printer_devno, 0, 1,
+			"USB printer gadget");
+	if (status) {
+		ERROR(dev, "alloc_chrdev_region %d\n", status);
+		class_destroy(usb_gadget_class);
+		return status;
+	}
+
+	status = usb_gadget_register_driver(&printer_driver);
+	if (status) {
+		class_destroy(usb_gadget_class);
+		unregister_chrdev_region(g_printer_devno, 1);
+		DBG(dev, "usb_gadget_register_driver %x\n", status);
+	}
+
+	return status;
+}
+module_init(init);
+
+static void __exit
+cleanup(void)
+{
+	int status;
+
+	spin_lock(&usb_printer_gadget.lock_printer_io);
+	class_destroy(usb_gadget_class);
+	unregister_chrdev_region(g_printer_devno, 2);
+
+	status = usb_gadget_unregister_driver(&printer_driver);
+	if (status)
+		ERROR(dev, "usb_gadget_unregister_driver %x\n", status);
+
+	spin_unlock(&usb_printer_gadget.lock_printer_io);
+}
+module_exit(cleanup);

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