USB: add gadget serial driver from Al Borchers

drivers/usb/gadget/Kconfig

@@ -177,6 +177,27 @@ config USB_GADGETFS_PXA2XX
 	depends on USB_GADGETFS && USB_PXA2XX
 	default y
 
+config USB_G_SERIAL
+	tristate "serial Gadget"
+	depends on USB_GADGET && (USB_DUMMY_HCD || USB_NET2280 || USB_PXA2XX || USB_SA1100)
+
+config USB_G_SERIAL_NET2280
+	bool
+	# for now, treat the "dummy" hcd as if it were a net2280
+	depends on USB_G_SERIAL && (USB_NET2280 || USB_DUMMY_HCD)
+	default y
+
+config USB_G_SERIAL_PXA2XX
+	bool
+	depends on USB_G_SERIAL && USB_PXA2XX
+	default y
+
+config USB_G_SERIAL_SA1100
+	bool
+	depends on USB_G_SERIAL && USB_SA1100
+	default y
+
+
 endchoice
 
 # endmenuconfig

drivers/usb/gadget/Makefile

@@ -8,9 +8,10 @@ obj-$(CONFIG_USB_NET2280)	+= net2280.o
 #
 g_zero-objs			:= zero.o usbstring.o
 g_ether-objs			:= ether.o usbstring.o
+g_serial-objs			:= serial.o usbstring.o
 gadgetfs-objs			:= inode.o usbstring.o
  
 obj-$(CONFIG_USB_ZERO)		+= g_zero.o
 obj-$(CONFIG_USB_ETH)		+= g_ether.o
 obj-$(CONFIG_USB_GADGETFS)	+= gadgetfs.o
-
+obj-$(CONFIG_USB_G_SERIAL)	+= g_serial.o

drivers/usb/gadget/serial.c

+/*
+ * g_serial.c -- USB gadget serial driver
+ *
+ * Copyright 2003 (C) Al Borchers (alborchers@steinerpoint.com)
+ *
+ * This code is based in part on the Gadget Zero driver, which
+ * is Copyright (C) 2003 by David Brownell, all rights reserved.
+ *
+ * This code also borrows from usbserial.c, which is
+ * Copyright (C) 1999 - 2002 Greg Kroah-Hartman (greg@kroah.com)
+ * Copyright (C) 2000 Peter Berger (pberger@brimson.com)
+ * Copyright (C) 2000 Al Borchers (alborchers@steinerpoint.com)
+ *
+ * This software is distributed under the terms of the GNU General
+ * Public License ("GPL") as published by the Free Software Foundation,
+ * either version 2 of that License or (at your option) any later version.
+ *
+ */
+
+#include <linux/config.h>
+#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/uts.h>
+#include <linux/version.h>
+#include <linux/wait.h>
+#include <linux/list.h>
+#include <linux/proc_fs.h>
+#include <linux/device.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+
+#include <asm/byteorder.h>
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <asm/system.h>
+#include <asm/unaligned.h>
+#include <asm/uaccess.h>
+
+#include <linux/usb_ch9.h>
+#include <linux/usb_gadget.h>
+
+
+/* Wait Cond */
+
+#define __wait_cond_interruptible(wq, condition, lock, flags, ret)	\
+do {									\
+	wait_queue_t __wait;						\
+	init_waitqueue_entry(&__wait, current);				\
+									\
+	add_wait_queue(&wq, &__wait);					\
+	for (;;) {							\
+		set_current_state(TASK_INTERRUPTIBLE);			\
+		if (condition)						\
+			break;						\
+		if (!signal_pending(current)) {				\
+			spin_unlock_irqrestore(lock, flags);		\
+			schedule();					\
+			spin_lock_irqsave(lock, flags);			\
+			continue;					\
+		}							\
+		ret = -ERESTARTSYS;					\
+		break;							\
+	}								\
+	current->state = TASK_RUNNING;					\
+	remove_wait_queue(&wq, &__wait);				\
+} while (0)
+	
+#define wait_cond_interruptible(wq, condition, lock, flags)		\
+({									\
+	int __ret = 0;							\
+	if (!(condition))						\
+		__wait_cond_interruptible(wq, condition, lock, flags,	\
+						__ret);			\
+	__ret;								\
+})
+
+#define __wait_cond_interruptible_timeout(wq, condition, lock, flags, 	\
+						timeout, ret)		\
+do {									\
+	signed long __timeout = timeout;				\
+	wait_queue_t __wait;						\
+	init_waitqueue_entry(&__wait, current);				\
+									\
+	add_wait_queue(&wq, &__wait);					\
+	for (;;) {							\
+		set_current_state(TASK_INTERRUPTIBLE);			\
+		if (__timeout == 0)					\
+			break;						\
+		if (condition)						\
+			break;						\
+		if (!signal_pending(current)) {				\
+			spin_unlock_irqrestore(lock, flags);		\
+			__timeout = schedule_timeout(__timeout);	\
+			spin_lock_irqsave(lock, flags);			\
+			continue;					\
+		}							\
+		ret = -ERESTARTSYS;					\
+		break;							\
+	}								\
+	current->state = TASK_RUNNING;					\
+	remove_wait_queue(&wq, &__wait);				\
+} while (0)
+	
+#define wait_cond_interruptible_timeout(wq, condition, lock, flags,	\
+						timeout)		\
+({									\
+	int __ret = 0;							\
+	if (!(condition))						\
+		__wait_cond_interruptible_timeout(wq, condition, lock,	\
+						flags, timeout, __ret);	\
+	__ret;								\
+})
+
+
+/* Defines */
+
+#define GS_VERSION_STR			"v0.1"
+#define GS_VERSION_NUM			0x0001
+
+#define GS_LONG_NAME			"Gadget Serial"
+#define GS_SHORT_NAME			"g_serial"
+
+#define GS_MAJOR			127
+#define GS_MINOR_START			0
+
+#define GS_NUM_PORTS			16
+
+#define GS_VENDOR_ID			0x05F9
+#define GS_PRODUCT_ID			0xFFFF
+
+#define GS_NUM_CONFIGS			1
+#define GS_NO_CONFIG_ID			0
+#define GS_BULK_CONFIG_ID		2
+
+#define GS_NUM_INTERFACES		1
+#define GS_INTERFACE_ID			0
+#define GS_ALT_INTERFACE_ID		0
+
+#define GS_NUM_ENDPOINTS		2
+
+#define GS_MAX_DESC_LEN			256
+
+#define GS_DEFAULT_READ_Q_SIZE		32
+#define GS_DEFAULT_WRITE_Q_SIZE		32
+
+#define GS_DEFAULT_WRITE_BUF_SIZE	8192
+#define GS_TMP_BUF_SIZE			8192
+
+#define GS_CLOSE_TIMEOUT		15
+
+/* debug macro */
+#if G_SERIAL_DEBUG
+
+static int debug = G_SERIAL_DEBUG;
+
+#define gs_debug(format, arg...) \
+	do { if (debug) printk(KERN_DEBUG format, ## arg); } while(0)
+#define gs_debug_level(level, format, arg...) \
+	do { if (debug>=level) printk(KERN_DEBUG format, ## arg); } while(0)
+
+#else
+
+#define gs_debug(format, arg...) \
+	do { } while(0)
+#define gs_debug_level(level, format, arg...) \
+	do { } while(0)
+
+#endif /* G_SERIAL_DEBUG */
+
+
+/* USB Controllers */
+
+/*
+ * NetChip 2280, PCI based.
+ *
+ * This has half a dozen configurable endpoints, four with dedicated
+ * DMA channels to manage their FIFOs.  It supports high speed.
+ * Those endpoints can be arranged in any desired configuration.
+ */
+#ifdef	CONFIG_USB_G_SERIAL_NET2280
+#define CHIP				"net2280"
+#define EP0_MAXPACKET			64
+static const char EP_OUT_NAME[] =	"ep-a";
+#define EP_OUT_NUM			2
+static const char EP_IN_NAME[] =	"ep-b";
+#define EP_IN_NUM			2
+#define HIGHSPEED
+#define SELFPOWER			USB_CONFIG_ATT_SELFPOWER
+
+extern int net2280_set_fifo_mode(struct usb_gadget *gadget, int mode);
+
+static inline void hw_optimize(struct usb_gadget *gadget)
+{
+	/* we can have bigger ep-a/ep-b fifos (2KB each, 4 packets
+	 * for highspeed bulk) because we're not using ep-c/ep-d.
+	 */
+	net2280_set_fifo_mode (gadget, 1);
+}
+#endif
+
+
+/*
+ * PXA-2xx UDC:  widely used in second gen Linux-capable PDAs.
+ *
+ * This has fifteen fixed-function full speed endpoints, and it
+ * can support all USB transfer types.
+ *
+ * These supports three or four configurations, with fixed numbers.
+ * The hardware interprets SET_INTERFACE, net effect is that you
+ * can't use altsettings or reset the interfaces independently.
+ * So stick to a single interface.
+ */
+#ifdef	CONFIG_USB_G_SERIAL_PXA2XX
+#define CHIP				"pxa2xx"
+#define EP0_MAXPACKET			16
+static const char EP_OUT_NAME[] =	"ep12out-bulk";
+#define EP_OUT_NUM			12
+static const char EP_IN_NAME[] =	"ep11in-bulk";
+#define EP_IN_NUM			11
+#define SELFPOWER 			USB_CONFIG_ATT_SELFPOWER
+
+/* no hw optimizations to apply */
+#define hw_optimize(g)			do {} while (0)
+#endif
+
+
+/*
+ * SA-1100 UDC:  widely used in first gen Linux-capable PDAs.
+ *
+ * This has only two fixed function endpoints, which can only
+ * be used for bulk (or interrupt) transfers.  (Plus control.)
+ *
+ * Since it can't flush its TX fifos without disabling the UDC,
+ * the current configuration or altsettings can't change except
+ * in special situations.  So this is a case of "choose it right
+ * during enumeration" ...
+ */
+#ifdef	CONFIG_USB_G_SERIAL_SA1100
+#define CHIP				"sa1100"
+#define EP0_MAXPACKET			8
+static const char EP_OUT_NAME[] =	"ep1out-bulk";
+#define EP_OUT_NUM			1
+static const char EP_IN_NAME [] =	"ep2in-bulk";
+#define EP_IN_NUM			2
+#define SELFPOWER			USB_CONFIG_ATT_SELFPOWER
+
+/* no hw optimizations to apply */
+#define hw_optimize(g)			do {} while (0)
+#endif
+
+
+/*
+ * Toshiba TC86C001 ("Goku-S") UDC
+ *
+ * This has three semi-configurable full speed bulk/interrupt endpoints.
+ */
+#ifdef	CONFIG_USB_G_SERIAL_GOKU
+#define CHIP				"goku"
+#define DRIVER_VERSION_NUM		0x0116
+#define EP0_MAXPACKET			8
+static const char EP_OUT_NAME [] =	"ep1-bulk";
+#define EP_OUT_NUM			1
+static const char EP_IN_NAME [] =	"ep2-bulk";
+#define EP_IN_NUM			2
+#define SELFPOWER			USB_CONFIG_ATT_SELFPOWER
+
+/* no hw optimizations to apply */
+#define hw_optimize(g)			do {} while (0)
+#endif
+
+/*
+ * USB Controller Defaults
+ */
+#ifndef EP0_MAXPACKET
+#error Configure some USB peripheral controller for g_serial!
+#endif
+
+#ifndef SELFPOWER
+/* default: say we rely on bus power */
+#define SELFPOWER   			0
+/* else value must be USB_CONFIG_ATT_SELFPOWER */
+#endif
+
+#ifndef	MAX_USB_POWER
+/* any hub supports this steady state bus power consumption */
+#define MAX_USB_POWER			100	/* mA */
+#endif
+
+#ifndef	WAKEUP
+/* default: this driver won't do remote wakeup */
+#define WAKEUP				0
+/* else value must be USB_CONFIG_ATT_WAKEUP */
+#endif
+
+
+/* Structures */
+
+struct gs_dev;
+
+/* circular buffer */
+struct gs_buf {
+	unsigned int		buf_size;
+	char			*buf_buf;
+	char			*buf_get;
+	char			*buf_put;
+};
+
+/* list of requests */
+struct gs_req_entry {
+	struct list_head	re_entry;
+	struct usb_request	*re_req;
+};
+
+/* the port structure holds info for each port, one for each minor number */
+struct gs_port {
+	struct gs_dev 		*port_dev;	/* pointer to device struct */
+	struct tty_struct	*port_tty;	/* pointer to tty struct */
+	spinlock_t		port_lock;
+	int 			port_num;
+	int			port_open_count;
+	int			port_in_use;	/* open/close in progress */
+	wait_queue_head_t	port_write_wait;/* waiting to write */
+	struct gs_buf		*port_write_buf;
+};
+
+/* the device structure holds info for the USB device */
+struct gs_dev {
+	struct usb_gadget	*dev_gadget;	/* gadget device pointer */
+	spinlock_t		dev_lock;	/* lock for set/reset config */
+	int			dev_config;	/* configuration number */
+	struct usb_ep		*dev_in_ep;	/* address of in endpoint */
+	struct usb_ep		*dev_out_ep;	/* address of out endpoint */
+	struct usb_request	*dev_ctrl_req;	/* control request */
+	struct list_head	dev_req_list;	/* list of write requests */
+	int			dev_sched_port;	/* round robin port scheduled */
+	struct gs_port		*dev_port[GS_NUM_PORTS]; /* the ports */
+};
+
+
+/* Functions */
+
+/* module */
+static int __init gs_module_init(void);
+static void __exit gs_module_exit(void);
+
+/* tty driver */
+static int gs_open(struct tty_struct *tty, struct file *file);
+static void gs_close(struct tty_struct *tty, struct file *file);
+static int gs_write(struct tty_struct *tty, int from_user,
+	const unsigned char *buf, int count);
+static void gs_put_char(struct tty_struct *tty, unsigned char ch);
+static void gs_flush_chars(struct tty_struct *tty);
+static int gs_write_room(struct tty_struct *tty);
+static int gs_chars_in_buffer(struct tty_struct *tty);
+static void gs_throttle(struct tty_struct * tty);
+static void gs_unthrottle(struct tty_struct * tty);
+static void gs_break(struct tty_struct *tty, int break_state);
+static int  gs_ioctl(struct tty_struct *tty, struct file *file,
+	unsigned int cmd, unsigned long arg);
+static void gs_set_termios(struct tty_struct *tty, struct termios *old);
+
+static int gs_send(struct gs_dev *dev);
+static int gs_send_packet(struct gs_dev *dev, char *packet,
+	unsigned int size);
+static int gs_recv_packet(struct gs_dev *dev, char *packet,
+	unsigned int size);
+static void gs_read_complete(struct usb_ep *ep, struct usb_request *req);
+static void gs_write_complete(struct usb_ep *ep, struct usb_request *req);
+
+/* gadget driver */
+static int gs_bind(struct usb_gadget *gadget);
+static void gs_unbind(struct usb_gadget *gadget);
+static int gs_setup(struct usb_gadget *gadget,
+	const struct usb_ctrlrequest *ctrl);
+static void gs_setup_complete(struct usb_ep *ep, struct usb_request *req);
+static void gs_disconnect(struct usb_gadget *gadget);
+static int gs_set_config(struct gs_dev *dev, unsigned config);
+static void gs_reset_config(struct gs_dev *dev);
+static int gs_build_config_desc(u8 *buf, enum usb_device_speed speed,
+		u8 type, unsigned int index);
+
+static struct usb_request *gs_alloc_req(struct usb_ep *ep, unsigned int len,
+	int kmalloc_flags);
+static void gs_free_req(struct usb_ep *ep, struct usb_request *req);
+
+static struct gs_req_entry *gs_alloc_req_entry(struct usb_ep *ep, unsigned len,
+	int kmalloc_flags);
+static void gs_free_req_entry(struct usb_ep *ep, struct gs_req_entry *req);
+
+static int gs_alloc_ports(struct gs_dev *dev, int kmalloc_flags);
+static void gs_free_ports(struct gs_dev *dev);
+
+/* circular buffer */
+static struct gs_buf *gs_buf_alloc(unsigned int size, int kmalloc_flags);
+static void gs_buf_free(struct gs_buf *gb);
+static void gs_buf_clear(struct gs_buf *gb);
+static unsigned int gs_buf_data_avail(struct gs_buf *gb);
+static unsigned int gs_buf_space_avail(struct gs_buf *gb);
+static unsigned int gs_buf_put(struct gs_buf *gb, const char *buf,
+	unsigned int count);
+static unsigned int gs_buf_get(struct gs_buf *gb, char *buf,
+	unsigned int count);
+
+
+/* Globals */
+
+static struct gs_dev *gs_device;
+
+static struct semaphore	gs_open_close_sem[GS_NUM_PORTS];
+
+static unsigned int read_q_size = GS_DEFAULT_READ_Q_SIZE;
+static unsigned int write_q_size = GS_DEFAULT_WRITE_Q_SIZE;
+
+static unsigned int write_buf_size = GS_DEFAULT_WRITE_BUF_SIZE;
+
+static unsigned char gs_tmp_buf[GS_TMP_BUF_SIZE];
+static struct semaphore	gs_tmp_buf_sem;
+
+/* tty driver struct */
+static struct tty_operations gs_tty_ops = {
+	.open =			gs_open,
+	.close =		gs_close,
+	.write =		gs_write,
+	.put_char =		gs_put_char,
+	.flush_chars =		gs_flush_chars,
+	.write_room =		gs_write_room,
+	.ioctl =		gs_ioctl,
+	.set_termios =		gs_set_termios,
+	.throttle =		gs_throttle,
+	.unthrottle =		gs_unthrottle,
+	.break_ctl =		gs_break,
+	.chars_in_buffer =	gs_chars_in_buffer,
+};
+static struct tty_driver *gs_tty_driver;
+
+/* gadget driver struct */
+static struct usb_gadget_driver gs_gadget_driver = {
+#ifdef HIGHSPEED
+	.speed =		USB_SPEED_HIGH,
+#else
+	.speed =		USB_SPEED_FULL,
+#endif
+	.function =		GS_LONG_NAME,
+	.bind =			gs_bind,
+	.unbind =		gs_unbind,
+	.setup =		gs_setup,
+	.disconnect =		gs_disconnect,
+	.driver = {
+		.name =		GS_SHORT_NAME,
+		/* .shutdown = ... */
+		/* .suspend = ...  */
+		/* .resume = ...   */
+	},
+};
+
+
+/* USB descriptors */
+
+#define GS_MANUFACTURER_STR_ID	1
+#define GS_PRODUCT_STR_ID	2
+#define GS_SERIAL_STR_ID	3
+#define GS_CONFIG_STR_ID	4
+
+/* static strings, in iso 8859/1 */
+static struct usb_string gs_strings[] = {
+	{ GS_MANUFACTURER_STR_ID, UTS_SYSNAME " " UTS_RELEASE " with " CHIP },
+	{ GS_PRODUCT_STR_ID, GS_LONG_NAME },
+	{ GS_SERIAL_STR_ID, "0" },
+	{ GS_CONFIG_STR_ID, "Bulk" },
+	{  } /* end of list */
+};
+
+static struct usb_gadget_strings gs_string_table = {
+	.language =		0x0409,	/* en-us */
+	.strings =		gs_strings,
+};
+
+static const struct usb_device_descriptor gs_device_desc = {
+	.bLength =		USB_DT_DEVICE_SIZE,
+	.bDescriptorType =	USB_DT_DEVICE,
+	.bcdUSB =		__constant_cpu_to_le16(0x0200),
+	.bDeviceClass =		USB_CLASS_VENDOR_SPEC,
+	.bMaxPacketSize0 =	EP0_MAXPACKET,
+	.idVendor =		__constant_cpu_to_le16(GS_VENDOR_ID),
+	.idProduct =		__constant_cpu_to_le16(GS_PRODUCT_ID),
+	.bcdDevice =		__constant_cpu_to_le16(GS_VERSION_NUM),
+	.iManufacturer =	GS_MANUFACTURER_STR_ID,
+	.iProduct =		GS_PRODUCT_STR_ID,
+	.iSerialNumber =	GS_SERIAL_STR_ID,
+	.bNumConfigurations =	GS_NUM_CONFIGS,
+};
+
+static const struct usb_config_descriptor gs_config_desc = {
+	.bLength =		USB_DT_CONFIG_SIZE,
+	.bDescriptorType =	USB_DT_CONFIG,
+	/* .wTotalLength set by gs_build_config_desc */
+	.bNumInterfaces =	GS_NUM_INTERFACES,
+	.bConfigurationValue =	GS_BULK_CONFIG_ID,
+	.iConfiguration =	GS_CONFIG_STR_ID,
+	.bmAttributes =		USB_CONFIG_ATT_ONE | SELFPOWER | WAKEUP,
+	.bMaxPower =		(MAX_USB_POWER + 1) / 2,
+};
+
+static const struct usb_interface_descriptor gs_interface_desc = {
+	.bLength =		USB_DT_INTERFACE_SIZE,
+	.bDescriptorType =	USB_DT_INTERFACE,
+	.bNumEndpoints =	GS_NUM_ENDPOINTS,
+	.bInterfaceClass =	USB_CLASS_VENDOR_SPEC,
+	.iInterface =		GS_CONFIG_STR_ID,
+};
+
+static const struct usb_endpoint_descriptor gs_fullspeed_in_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bEndpointAddress =	EP_IN_NUM | USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	__constant_cpu_to_le16(64),
+};
+
+static const struct usb_endpoint_descriptor gs_fullspeed_out_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bEndpointAddress =	EP_OUT_NUM | USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	__constant_cpu_to_le16(64),
+};
+
+static const struct usb_endpoint_descriptor gs_highspeed_in_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bEndpointAddress =	EP_IN_NUM | USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	__constant_cpu_to_le16(512),
+};
+
+static const struct usb_endpoint_descriptor gs_highspeed_out_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+	.bEndpointAddress =	EP_OUT_NUM | USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	__constant_cpu_to_le16(512),
+};
+
+#ifdef HIGHSPEED
+static const struct usb_qualifier_descriptor gs_qualifier_desc = {
+	.bLength =		sizeof(struct usb_qualifier_descriptor),
+	.bDescriptorType =	USB_DT_DEVICE_QUALIFIER,
+	.bcdUSB =		__constant_cpu_to_le16 (0x0200),
+	.bDeviceClass =		USB_CLASS_VENDOR_SPEC,
+	/* assumes ep0 uses the same value for both speeds ... */
+	.bMaxPacketSize0 =	EP0_MAXPACKET,
+	.bNumConfigurations =	GS_NUM_CONFIGS,
+};
+#endif
+
+
+/* Module */
+MODULE_DESCRIPTION(GS_LONG_NAME);
+MODULE_AUTHOR("Al Borchers");
+MODULE_LICENSE("GPL");
+
+MODULE_PARM(debug, "i");
+MODULE_PARM_DESC(debug, "Enable debugging, 0=off, 1=on");
+
+MODULE_PARM(read_q_size, "i");
+MODULE_PARM_DESC(read_q_size, "Read request queue size, default=32");
+
+MODULE_PARM(write_q_size, "i");
+MODULE_PARM_DESC(write_q_size, "Write request queue size, default=32");
+
+MODULE_PARM(write_buf_size, "i");
+MODULE_PARM_DESC(write_buf_size, "Write buffer size, default=8192");
+
+module_init(gs_module_init);
+module_exit(gs_module_exit);
+
+/*
+*  gs_module_init
+*
+*  Register as a USB gadget driver and a tty driver.
+*/
+static int __init gs_module_init(void)
+{
+	int i;
+	int retval;
+
+	retval = usb_gadget_register_driver(&gs_gadget_driver);
+	if (retval) {
+		printk(KERN_ERR "gs_module_init: cannot register gadget driver, ret=%d\n", retval);
+		return retval;
+	}
+
+	gs_tty_driver = alloc_tty_driver(GS_NUM_PORTS);
+	if (!gs_tty_driver)
+		return -ENOMEM;
+	gs_tty_driver->owner = THIS_MODULE;
+	gs_tty_driver->driver_name = GS_SHORT_NAME;
+	gs_tty_driver->name = "ttygs";
+	gs_tty_driver->devfs_name = "usb/ttygs/";
+	gs_tty_driver->major = GS_MAJOR;
+	gs_tty_driver->minor_start = GS_MINOR_START;
+	gs_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
+	gs_tty_driver->subtype = SERIAL_TYPE_NORMAL;
+	gs_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_NO_DEVFS;
+	gs_tty_driver->init_termios = tty_std_termios;
+	gs_tty_driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
+	tty_set_operations(gs_tty_driver, &gs_tty_ops);
+
+	for (i=0; i < GS_NUM_PORTS; i++)
+		sema_init(&gs_open_close_sem[i], 1);
+
+	sema_init(&gs_tmp_buf_sem, 1);
+
+	retval = tty_register_driver(gs_tty_driver);
+	if (retval) {
+		usb_gadget_unregister_driver(&gs_gadget_driver);
+		put_tty_driver(gs_tty_driver);
+		printk(KERN_ERR "gs_module_init: cannot register tty driver, ret=%d\n", retval);
+		return retval;
+	}
+
+	printk(KERN_INFO "gs_module_init: %s %s loaded\n", GS_LONG_NAME, GS_VERSION_STR);
+	return 0;
+}
+
+/*
+* gs_module_exit
+*
+* Unregister as a tty driver and a USB gadget driver.
+*/
+static void __exit gs_module_exit(void)
+{
+	tty_unregister_driver(gs_tty_driver);
+	put_tty_driver(gs_tty_driver);
+	usb_gadget_unregister_driver(&gs_gadget_driver);
+
+	printk(KERN_INFO "gs_module_exit: %s %s unloaded\n", GS_LONG_NAME, GS_VERSION_STR);
+}
+
+/* TTY Driver */
+
+/*
+ * gs_open
+ */
+static int gs_open(struct tty_struct *tty, struct file *file)
+{
+	int port_num;
+	unsigned long flags;
+	struct gs_port *port;
+	struct gs_dev *dev;
+	struct gs_buf *buf;
+	struct semaphore *sem;
+
+	port_num = tty->index;
+
+	gs_debug("gs_open: (%d,%p,%p)\n", port_num, tty, file);
+
+	tty->driver_data = NULL;
+
+	if (port_num < 0 || port_num >= GS_NUM_PORTS) {
+		printk(KERN_ERR "gs_open: (%d,%p,%p) invalid port number\n",
+			port_num, tty, file);
+		return -ENODEV;
+	}
+
+	dev = gs_device;
+
+	if (dev == NULL) {
+		printk(KERN_ERR "gs_open: (%d,%p,%p) NULL device pointer\n",
+			port_num, tty, file);
+		return -ENODEV;
+	}
+
+	sem = &gs_open_close_sem[port_num];
+	if (down_interruptible(sem)) {
+		printk(KERN_ERR
+		"gs_open: (%d,%p,%p) interrupted waiting for semaphore\n",
+			port_num, tty, file);
+		return -ERESTARTSYS;
+	}
+
+	spin_lock_irqsave(&dev->dev_lock, flags);
+
+	if (dev->dev_config == GS_NO_CONFIG_ID) {
+		printk(KERN_ERR
+			"gs_open: (%d,%p,%p) device is not connected\n",
+			port_num, tty, file);
+		spin_unlock_irqrestore(&dev->dev_lock, flags);
+		up(sem);
+		return -ENODEV;
+	}
+
+	port = dev->dev_port[port_num];
+
+	if (port == NULL) {
+		printk(KERN_ERR "gs_open: (%d,%p,%p) NULL port pointer\n",
+			port_num, tty, file);
+		spin_unlock_irqrestore(&dev->dev_lock, flags);
+		up(sem);
+		return -ENODEV;
+	}
+
+	spin_lock(&port->port_lock);
+	spin_unlock(&dev->dev_lock);
+
+	if (port->port_dev == NULL) {
+		printk(KERN_ERR "gs_open: (%d,%p,%p) port disconnected (1)\n",
+			port_num, tty, file);
+		spin_unlock_irqrestore(&port->port_lock, flags);
+		up(sem);
+		return -EIO;
+	}
+
+	if (port->port_open_count > 0) {
+		++port->port_open_count;
+		spin_unlock_irqrestore(&port->port_lock, flags);
+		gs_debug("gs_open: (%d,%p,%p) already open\n",
+			port_num, tty, file);
+		up(sem);
+		return 0;
+	}
+
+	/* mark port as in use, we can drop port lock and sleep if necessary */
+	port->port_in_use = 1;
+
+	/* allocate write buffer on first open */
+	if (port->port_write_buf == NULL) {
+		spin_unlock_irqrestore(&port->port_lock, flags);
+		buf = gs_buf_alloc(write_buf_size, GFP_KERNEL);
+		spin_lock_irqsave(&port->port_lock, flags);
+
+		/* might have been disconnected while asleep, check */
+		if (port->port_dev == NULL) {
+			printk(KERN_ERR
+				"gs_open: (%d,%p,%p) port disconnected (2)\n",
+				port_num, tty, file);
+			port->port_in_use = 0;
+			spin_unlock_irqrestore(&port->port_lock, flags);
+			up(sem);
+			return -EIO;
+		}
+
+		if ((port->port_write_buf=buf) == NULL) {
+			printk(KERN_ERR "gs_open: (%d,%p,%p) cannot allocate port write buffer\n",
+				port_num, tty, file);
+			port->port_in_use = 0;
+			spin_unlock_irqrestore(&port->port_lock, flags);
+			up(sem);
+			return -ENOMEM;
+		}
+
+	}
+
+	/* wait for carrier detect (not implemented) */
+
+	/* might have been disconnected while asleep, check */
+	if (port->port_dev == NULL) {
+		printk(KERN_ERR "gs_open: (%d,%p,%p) port disconnected (3)\n",
+			port_num, tty, file);
+		port->port_in_use = 0;
+		spin_unlock_irqrestore(&port->port_lock, flags);
+		up(sem);
+		return -EIO;
+	}
+
+	tty->driver_data = port;
+	port->port_tty = tty;
+	port->port_open_count = 1;
+	port->port_in_use = 0;
+
+	spin_unlock_irqrestore(&port->port_lock, flags);
+	up(sem);
+
+	gs_debug("gs_open: (%d,%p,%p) completed\n", port_num, tty, file);
+
+	return 0;
+}
+
+/*
+ * gs_close
+ */
+static void gs_close(struct tty_struct *tty, struct file *file)
+{
+	unsigned long flags;
+	struct gs_port *port = tty->driver_data;
+	struct semaphore *sem;
+
+	if (port == NULL) {
+		printk(KERN_ERR "gs_close: NULL port pointer\n");
+		return;
+	}
+
+	gs_debug("gs_close: (%d,%p,%p)\n", port->port_num, tty, file);
+
+	sem = &gs_open_close_sem[port->port_num];
+	down(sem);
+
+	spin_lock_irqsave(&port->port_lock, flags);
+
+	if (port->port_open_count == 0) {
+		printk(KERN_ERR
+			"gs_close: (%d,%p,%p) port is already closed\n",
+			port->port_num, tty, file);
+		spin_unlock_irqrestore(&port->port_lock, flags);
+		up(sem);
+		return;
+	}
+
+	if (port->port_open_count > 0) {
+		--port->port_open_count;
+		spin_unlock_irqrestore(&port->port_lock, flags);
+		up(sem);
+		return;
+	}
+
+	/* free disconnected port on final close */
+	if (port->port_dev == NULL) {
+		kfree(port);
+		spin_unlock_irqrestore(&port->port_lock, flags);
+		up(sem);
+		return;
+	}
+
+	/* mark port as closed but in use, we can drop port lock */
+	/* and sleep if necessary */
+	port->port_in_use = 1;
+	port->port_open_count = 0;
+
+	/* wait for write buffer to drain, or */
+	/* at most GS_CLOSE_TIMEOUT seconds */
+	if (gs_buf_data_avail(port->port_write_buf) > 0) {
+		wait_cond_interruptible_timeout(port->port_write_wait,
+		port->port_dev == NULL
+		|| gs_buf_data_avail(port->port_write_buf) == 0,
+		&port->port_lock, flags, GS_CLOSE_TIMEOUT * HZ);
+	}
+
+	/* free disconnected port on final close */
+	/* (might have happened during the above sleep) */
+	if (port->port_dev == NULL) {
+		kfree(port);
+		spin_unlock_irqrestore(&port->port_lock, flags);
+		up(sem);
+		return;
+	}
+
+	gs_buf_clear(port->port_write_buf);
+
+	tty->driver_data = NULL;
+	port->port_tty = NULL;
+	port->port_in_use = 0;
+
+	spin_unlock_irqrestore(&port->port_lock, flags);
+	up(sem);
+
+	gs_debug("gs_close: (%d,%p,%p) completed\n",
+		port->port_num, tty, file);
+}
+
+/*
+ * gs_write
+ */
+static int gs_write(struct tty_struct *tty, int from_user, const unsigned char *buf, int count)
+{
+	unsigned long flags;
+	struct gs_port *port = tty->driver_data;
+
+	if (port == NULL) {
+		printk(KERN_ERR "gs_write: NULL port pointer\n");
+		return -EIO;
+	}
+
+	gs_debug("gs_write: (%d,%p) writing %d bytes\n", port->port_num, tty,
+		count);
+
+	if (count == 0)
+		return 0;
+
+	/* copy from user into tmp buffer, get tmp_buf semaphore */
+	if (from_user) {
+		if (count > GS_TMP_BUF_SIZE)
+			count = GS_TMP_BUF_SIZE;
+		down(&gs_tmp_buf_sem);
+		if (copy_from_user(gs_tmp_buf, buf, count) != 0) {
+			up(&gs_tmp_buf_sem);
+			printk(KERN_ERR
+			"gs_write: (%d,%p) cannot copy from user space\n",
+				port->port_num, tty);
+			return -EFAULT;
+		}
+		buf = gs_tmp_buf;
+	}
+
+	spin_lock_irqsave(&port->port_lock, flags);
+
+	if (port->port_dev == NULL) {
+		printk(KERN_ERR "gs_write: (%d,%p) port is not connected\n",
+			port->port_num, tty);
+		spin_unlock_irqrestore(&port->port_lock, flags);
+		if (from_user)
+			up(&gs_tmp_buf_sem);
+		return -EIO;
+	}
+
+	if (port->port_open_count == 0) {
+		printk(KERN_ERR "gs_write: (%d,%p) port is closed\n",
+			port->port_num, tty);
+		spin_unlock_irqrestore(&port->port_lock, flags);
+		if (from_user)
+			up(&gs_tmp_buf_sem);
+		return -EBADF;
+	}
+
+	count = gs_buf_put(port->port_write_buf, buf, count);
+
+	spin_unlock_irqrestore(&port->port_lock, flags);
+
+	if (from_user)
+		up(&gs_tmp_buf_sem);
+
+	gs_send(gs_device);
+
+	gs_debug("gs_write: (%d,%p) wrote %d bytes\n", port->port_num, tty,
+		count);
+
+	return count;
+}
+
+/*
+ * gs_put_char
+ */
+static void gs_put_char(struct tty_struct *tty, unsigned char ch)
+{
+	unsigned long flags;
+	struct gs_port *port = tty->driver_data;
+
+	if (port == NULL) {
+		printk(KERN_ERR "gs_put_char: NULL port pointer\n");
+		return;
+	}
+
+	gs_debug("gs_put_char: (%d,%p) char=0x%x, called from %p, %p, %p\n", port->port_num, tty, ch, __builtin_return_address(0), __builtin_return_address(1), __builtin_return_address(2));
+
+	spin_lock_irqsave(&port->port_lock, flags);
+
+	if (port->port_dev == NULL) {
+		printk(KERN_ERR "gs_put_char: (%d,%p) port is not connected\n",
+			port->port_num, tty);
+		spin_unlock_irqrestore(&port->port_lock, flags);
+		return;
+	}
+
+	if (port->port_open_count == 0) {
+		printk(KERN_ERR "gs_put_char: (%d,%p) port is closed\n",
+			port->port_num, tty);
+		spin_unlock_irqrestore(&port->port_lock, flags);
+		return;
+	}
+
+	gs_buf_put(port->port_write_buf, &ch, 1);
+
+	spin_unlock_irqrestore(&port->port_lock, flags);
+}
+
+/*
+ * gs_flush_chars
+ */
+static void gs_flush_chars(struct tty_struct *tty)
+{
+	unsigned long flags;
+	struct gs_port *port = tty->driver_data;
+
+	if (port == NULL) {
+		printk(KERN_ERR "gs_flush_chars: NULL port pointer\n");
+		return;
+	}
+
+	gs_debug("gs_flush_chars: (%d,%p)\n", port->port_num, tty);
+
+	spin_lock_irqsave(&port->port_lock, flags);
+
+	if (port->port_dev == NULL) {
+		printk(KERN_ERR
+			"gs_flush_chars: (%d,%p) port is not connected\n",
+			port->port_num, tty);
+		spin_unlock_irqrestore(&port->port_lock, flags);
+		return;
+	}
+
+	if (port->port_open_count == 0) {
+		printk(KERN_ERR "gs_flush_chars: (%d,%p) port is closed\n",
+			port->port_num, tty);
+		spin_unlock_irqrestore(&port->port_lock, flags);
+		return;
+	}
+
+	spin_unlock_irqrestore(&port->port_lock, flags);
+
+	gs_send(gs_device);
+}
+
+/*
+ * gs_write_room
+ */
+static int gs_write_room(struct tty_struct *tty)
+{
+
+	int room = 0;
+	unsigned long flags;
+	struct gs_port *port = tty->driver_data;
+
+
+	if (port == NULL)
+		return 0;
+
+	spin_lock_irqsave(&port->port_lock, flags);
+
+	if (port->port_dev != NULL && port->port_open_count > 0
+	&& port->port_write_buf != NULL)
+		room = gs_buf_space_avail(port->port_write_buf);
+
+	spin_unlock_irqrestore(&port->port_lock, flags);
+
+	gs_debug("gs_write_room: (%d,%p) room=%d\n",
+		port->port_num, tty, room);
+
+	return room;
+}
+
+/*
+ * gs_chars_in_buffer
+ */
+static int gs_chars_in_buffer(struct tty_struct *tty)
+{
+	int chars = 0;
+	unsigned long flags;
+	struct gs_port *port = tty->driver_data;
+
+	if (port == NULL)
+		return 0;
+
+	spin_lock_irqsave(&port->port_lock, flags);
+
+	if (port->port_dev != NULL && port->port_open_count > 0
+	&& port->port_write_buf != NULL)
+		chars = gs_buf_data_avail(port->port_write_buf);
+
+	spin_unlock_irqrestore(&port->port_lock, flags);
+
+	gs_debug("gs_chars_in_buffer: (%d,%p) chars=%d\n",
+		port->port_num, tty, chars);
+
+	return chars;
+}
+
+/*
+ * gs_throttle
+ */
+static void gs_throttle(struct tty_struct *tty)
+{
+}
+
+/*
+ * gs_unthrottle
+ */
+static void gs_unthrottle(struct tty_struct *tty)
+{
+}
+
+/*
+ * gs_break
+ */
+static void gs_break(struct tty_struct *tty, int break_state)
+{
+}
+
+/*
+ * gs_ioctl
+ */
+static int gs_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct gs_port *port = tty->driver_data;
+
+	if (port == NULL) {
+		printk(KERN_ERR "gs_ioctl: NULL port pointer\n");
+		return -EIO;
+	}
+
+	gs_debug("gs_ioctl: (%d,%p,%p) cmd=0x%4.4x, arg=%lu\n",
+		port->port_num, tty, file, cmd, arg);
+
+	/* handle ioctls */
+
+	/* could not handle ioctl */
+	return -ENOIOCTLCMD;
+}
+
+/*
+ * gs_set_termios
+ */
+static void gs_set_termios(struct tty_struct *tty, struct termios *old)
+{
+}
+
+/*
+* gs_send
+*
+* This function finds available write requests, calls
+* gs_send_packet to fill these packets with data, and
+* continues until either there are no more write requests
+* available or no more data to send.  This function is
+* run whenever data arrives or write requests are available.
+*/
+static int gs_send(struct gs_dev *dev)
+{
+	int ret,len;
+	unsigned long flags;
+	struct usb_ep *ep;
+	struct usb_request *req;
+	struct gs_req_entry *req_entry;
+
+	if (dev == NULL) {
+		printk(KERN_ERR "gs_send: NULL device pointer\n");
+		return -ENODEV;
+	}
+
+	spin_lock_irqsave(&dev->dev_lock, flags);
+
+	ep = dev->dev_in_ep;
+
+	while(!list_empty(&dev->dev_req_list)) {
+
+		req_entry = list_entry(dev->dev_req_list.next,
+			struct gs_req_entry, re_entry);
+
+		req = req_entry->re_req;
+
+		len = gs_send_packet(dev, req->buf, ep->maxpacket);
+
+		if (len > 0) {
+gs_debug_level(3, "gs_send: len=%d, 0x%2.2x 0x%2.2x 0x%2.2x ...\n", len, *((unsigned char *)req->buf), *((unsigned char *)req->buf+1), *((unsigned char *)req->buf+2));
+			list_del(&req_entry->re_entry);
+			req->length = len;
+			if ((ret=usb_ep_queue(ep, req, GFP_ATOMIC))) {
+				printk(KERN_ERR
+				"gs_send: cannot queue read request, ret=%d\n",
+					ret);
+				break;
+			}
+		} else {
+			break;
+		}
+
+	}
+
+	spin_unlock_irqrestore(&dev->dev_lock, flags);
+
+	return 0;
+}
+
+/*
+ * gs_send_packet
+ *
+ * If there is data to send, a packet is built in the given
+ * buffer and the size is returned.  If there is no data to
+ * send, 0 is returned.  If there is any error a negative
+ * error number is returned.
+ *
+ * Called during USB completion routine, on interrupt time.
+ *
+ * We assume that disconnect will not happen until all completion
+ * routines have completed, so we can assume that the dev_port
+ * array does not change during the lifetime of this function.
+ */
+static int gs_send_packet(struct gs_dev *dev, char *packet, unsigned int size)
+{
+	unsigned int len;
+	struct gs_port *port;
+
+	/* TEMPORARY -- only port 0 is supported right now */
+	port = dev->dev_port[0];
+
+	if (port == NULL) {
+		printk(KERN_ERR
+			"gs_send_packet: port=%d, NULL port pointer\n",
+			0);
+		return -EIO;
+	}
+
+	spin_lock(&port->port_lock);
+
+	len = gs_buf_data_avail(port->port_write_buf);
+	if (len < size)
+		size = len;
+
+	if (size == 0) {
+		spin_unlock(&port->port_lock);
+		return 0;
+	}
+
+	size = gs_buf_get(port->port_write_buf, packet, size);
+
+	wake_up_interruptible(&port->port_tty->write_wait);
+
+	spin_unlock(&port->port_lock);
+
+	return size;
+}
+
+/*
+ * gs_recv_packet
+ *
+ * Called for each USB packet received.  Reads the packet
+ * header and stuffs the data in the appropriate tty buffer.
+ * Returns 0 if successful, or a negative error number.
+ *
+ * Called during USB completion routine, on interrupt time.
+ *
+ * We assume that disconnect will not happen until all completion
+ * routines have completed, so we can assume that the dev_port
+ * array does not change during the lifetime of this function.
+ */
+static int gs_recv_packet(struct gs_dev *dev, char *packet, unsigned int size)
+{
+	unsigned int len;
+	struct gs_port *port;
+
+	/* TEMPORARY -- only port 0 is supported right now */
+	port = dev->dev_port[0];
+
+	if (port == NULL) {
+		printk(KERN_ERR "gs_recv_packet: port=%d, NULL port pointer\n",
+			port->port_num);
+		return -EIO;
+	}
+
+	spin_lock(&port->port_lock);
+
+	if (port->port_tty == NULL) {
+		printk(KERN_ERR "gs_recv_packet: port=%d, NULL tty pointer\n",
+			port->port_num);
+		spin_unlock(&port->port_lock);
+		return -EIO;
+	}
+
+	if (port->port_tty->magic != TTY_MAGIC) {
+		printk(KERN_ERR "gs_recv_packet: port=%d, bad tty magic\n",
+			port->port_num);
+		spin_unlock(&port->port_lock);
+		return -EIO;
+	}
+
+	len = (unsigned int)(TTY_FLIPBUF_SIZE - port->port_tty->flip.count);
+	if (len < size)
+		size = len;
+
+	if (size > 0) {
+		memcpy(port->port_tty->flip.char_buf_ptr, packet, size);
+		port->port_tty->flip.char_buf_ptr += size;
+		port->port_tty->flip.count += size;
+		tty_flip_buffer_push(port->port_tty);
+		wake_up_interruptible(&port->port_tty->read_wait);
+	}
+
+	spin_unlock(&port->port_lock);
+
+	return 0;
+}
+
+/*
+* gs_read_complete
+*/
+static void gs_read_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	int ret;
+	struct gs_dev *dev = ep->driver_data;
+
+	if (dev == NULL) {
+		printk(KERN_ERR "gs_read_complete: NULL device pointer\n");
+		return;
+	}
+
+	switch(req->status) {
+	case 0:
+ 		/* normal completion */
+		gs_recv_packet(dev, req->buf, req->actual);
+requeue:
+		req->length = ep->maxpacket;
+		if ((ret=usb_ep_queue(ep, req, GFP_ATOMIC))) {
+			printk(KERN_ERR
+			"gs_read_complete: cannot queue read request, ret=%d\n",
+				ret);
+		}
+		break;
+
+	case -ESHUTDOWN:
+		/* disconnect */
+		gs_debug("gs_read_complete: shutdown\n");
+		gs_free_req(ep, req);
+		break;
+
+	default:
+		/* unexpected */
+		printk(KERN_ERR
+		"gs_read_complete: unexpected status error, status=%d\n",
+			req->status);
+		goto requeue;
+		break;
+	}
+}
+
+/*
+* gs_write_complete
+*/
+static void gs_write_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct gs_dev *dev = ep->driver_data;
+	struct gs_req_entry *gs_req = req->context;
+
+	if (dev == NULL) {
+		printk(KERN_ERR "gs_write_complete: NULL device pointer\n");
+		return;
+	}
+
+	switch(req->status) {
+	case 0:
+		/* normal completion */
+requeue:
+		if (gs_req == NULL) {
+			printk(KERN_ERR
+				"gs_write_complete: NULL request pointer\n");
+			return;
+		}
+
+		spin_lock(&dev->dev_lock);
+		list_add(&gs_req->re_entry, &dev->dev_req_list);
+		spin_unlock(&dev->dev_lock);
+
+		gs_send(dev);
+
+		break;
+
+	case -ESHUTDOWN:
+		/* disconnect */
+		gs_debug("gs_write_complete: shutdown\n");
+		gs_free_req(ep, req);
+		break;
+
+	default:
+		printk(KERN_ERR
+		"gs_write_complete: unexpected status error, status=%d\n",
+			req->status);
+		goto requeue;
+		break;
+	}
+}
+
+/* Gadget Driver */
+
+/*
+ * gs_bind
+ *
+ * Called on module load.  Allocates and initializes the device
+ * structure and a control request.
+ */
+static int gs_bind(struct usb_gadget *gadget)
+{
+	int ret;
+	struct gs_dev *dev;
+
+	gs_device = dev = kmalloc(sizeof(struct gs_dev), GFP_KERNEL);
+	if (dev == NULL)
+		return -ENOMEM;
+
+	set_gadget_data(gadget, dev);
+
+	memset(dev, 0, sizeof(struct gs_dev));
+	dev->dev_gadget = gadget;
+	spin_lock_init(&dev->dev_lock);
+	INIT_LIST_HEAD(&dev->dev_req_list);
+
+	if ((ret=gs_alloc_ports(dev, GFP_KERNEL)) != 0) {
+		printk(KERN_ERR "gs_bind: cannot allocate ports\n");
+		gs_unbind(gadget);
+		return ret;
+	}
+
+	/* preallocate control response and buffer */
+	dev->dev_ctrl_req = gs_alloc_req(gadget->ep0, GS_MAX_DESC_LEN,
+		GFP_KERNEL);
+	if (dev->dev_ctrl_req == NULL) {
+		gs_unbind(gadget);
+		return -ENOMEM;
+	}
+	dev->dev_ctrl_req->complete = gs_setup_complete;
+
+	gadget->ep0->driver_data = dev;
+
+	printk(KERN_INFO "gs_bind: %s %s bound\n",
+		GS_LONG_NAME, GS_VERSION_STR);
+
+	return 0;
+}
+
+/*
+ * gs_unbind
+ *
+ * Called on module unload.  Frees the control request and device
+ * structure.
+ */
+static void gs_unbind(struct usb_gadget *gadget)
+{
+	struct gs_dev *dev = get_gadget_data(gadget);
+
+	gs_device = NULL;
+
+	/* read/write requests already freed, only control request remains */
+	if (dev != NULL) {
+		if (dev->dev_ctrl_req != NULL)
+			gs_free_req(gadget->ep0, dev->dev_ctrl_req);
+		gs_free_ports(dev);
+		kfree(dev);
+		set_gadget_data(gadget, NULL);
+	}
+
+	printk(KERN_INFO "gs_unbind: %s %s unbound\n", GS_LONG_NAME,
+		GS_VERSION_STR);
+}
+
+/*
+ * gs_setup
+ *
+ * Implements all the control endpoint functionality that's not
+ * handled in hardware or the hardware driver.
+ *
+ * Returns the size of the data sent to the host, or a negative
+ * error number.
+ */
+static int gs_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
+{
+	int ret = -EOPNOTSUPP;
+	unsigned int sv_config;
+	struct gs_dev *dev = get_gadget_data(gadget);
+	struct usb_request *req = dev->dev_ctrl_req;
+
+	switch (ctrl->bRequest) {
+	case USB_REQ_GET_DESCRIPTOR:
+		if (ctrl->bRequestType != USB_DIR_IN)
+			break;
+
+		switch (ctrl->wValue >> 8) {
+		case USB_DT_DEVICE:
+			ret = min(ctrl->wLength,
+				(u16)sizeof(struct usb_device_descriptor));
+			memcpy(req->buf, &gs_device_desc, ret);
+			break;
+
+#ifdef HIGHSPEED
+		case USB_DT_DEVICE_QUALIFIER:
+			ret = min(ctrl->wLength,
+				(u16)sizeof(struct usb_qualifier_descriptor));
+			memcpy(req->buf, &gs_qualifier_desc, ret);
+			break;
+
+		case USB_DT_OTHER_SPEED_CONFIG:
+#endif /* HIGHSPEED */
+		case USB_DT_CONFIG:
+			ret = gs_build_config_desc(req->buf, gadget->speed,
+				ctrl->wValue >> 8, ctrl->wValue & 0xff);
+			if (ret >= 0)
+				ret = min(ctrl->wLength, (u16)ret);
+			break;
+
+		case USB_DT_STRING:
+			/* wIndex == language code. */
+			ret = usb_gadget_get_string(&gs_string_table,
+				ctrl->wValue & 0xff, req->buf);
+			if (ret >= 0)
+				ret = min(ctrl->wLength, (u16)ret);
+			break;
+		}
+		break;
+
+	case USB_REQ_SET_CONFIGURATION:
+		if (ctrl->bRequestType != 0)
+			break;
+		spin_lock(&dev->dev_lock);
+		ret = gs_set_config(dev, ctrl->wValue);
+		spin_unlock(&dev->dev_lock);
+		break;
+
+	case USB_REQ_GET_CONFIGURATION:
+		if (ctrl->bRequestType != USB_DIR_IN)
+			break;
+		*(u8 *)req->buf = dev->dev_config;
+		ret = min(ctrl->wLength, (u16)1);
+		break;
+
+	case USB_REQ_SET_INTERFACE:
+		if (ctrl->bRequestType != USB_RECIP_INTERFACE)
+			break;
+		spin_lock(&dev->dev_lock);
+		if (dev->dev_config == GS_BULK_CONFIG_ID
+		&& ctrl->wIndex == GS_INTERFACE_ID
+		&& ctrl->wValue == GS_ALT_INTERFACE_ID) {
+			sv_config = dev->dev_config;
+			/* since there is only one interface, setting the */
+			/* interface is equivalent to setting the config */
+			gs_reset_config(dev);
+			gs_set_config(dev, sv_config);
+			ret = 0;
+		}
+		spin_unlock(&dev->dev_lock);
+		break;
+
+	case USB_REQ_GET_INTERFACE:
+		if (ctrl->bRequestType != (USB_DIR_IN|USB_RECIP_INTERFACE))
+			break;
+		if (dev->dev_config == GS_NO_CONFIG_ID)
+			break;
+		if (ctrl->wIndex != GS_INTERFACE_ID) {
+			ret = -EDOM;
+			break;
+		}
+		*(u8 *)req->buf = GS_ALT_INTERFACE_ID;
+		ret = min(ctrl->wLength, (u16)1);
+		break;
+
+	default:
+		printk(KERN_ERR "gs_setup: unknown request, type=%02x, request=%02x, value=%04x, index=%04x, length=%d\n",
+			ctrl->bRequestType, ctrl->bRequest, ctrl->wValue,
+			ctrl->wIndex, ctrl->wLength);
+		break;
+
+	}
+
+	/* respond with data transfer before status phase? */
+	if (ret >= 0) {
+		req->length = ret;
+		ret = usb_ep_queue(gadget->ep0, req, GFP_ATOMIC);
+		if (ret < 0) {
+			printk(KERN_ERR
+				"gs_setup: cannot queue response, ret=%d\n",
+				ret);
+			req->status = 0;
+			gs_setup_complete(gadget->ep0, req);
+		}
+	}
+
+	/* device either stalls (ret < 0) or reports success */
+	return ret;
+}
+
+/*
+ * gs_setup_complete
+ */
+static void gs_setup_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	if (req->status || req->actual != req->length) {
+		printk(KERN_ERR "gs_setup_complete: status error, status=%d, actual=%d, length=%d\n",
+			req->status, req->actual, req->length);
+	}
+}
+
+/*
+ * gs_disconnect
+ *
+ * Called when the device is disconnected.  Frees the closed
+ * ports and disconnects open ports.  Open ports will be freed
+ * on close.  Then reallocates the ports for the next connection.
+ */
+static void gs_disconnect(struct usb_gadget *gadget)
+{
+	unsigned long flags;
+	struct gs_dev *dev = get_gadget_data(gadget);
+
+	spin_lock_irqsave(&dev->dev_lock, flags);
+
+	gs_reset_config(dev);
+
+	/* free closed ports and disconnect open ports */
+	/* (open ports will be freed when closed) */
+	gs_free_ports(dev);
+
+	/* re-allocate ports for the next connection */
+	if (gs_alloc_ports(dev, GFP_ATOMIC) != 0)
+		printk(KERN_ERR "gs_disconnect: cannot re-allocate ports\n");
+
+	spin_unlock_irqrestore(&dev->dev_lock, flags);
+
+	printk(KERN_INFO "gs_disconnect: %s disconnected\n", GS_LONG_NAME);
+}
+
+/*
+ * gs_set_config
+ *
+ * Configures the device by enabling device specific
+ * optimizations, setting up the endpoints, allocating
+ * read and write requests and queuing read requests.
+ *
+ * The device lock must be held when calling this function.
+ */
+static int gs_set_config(struct gs_dev *dev, unsigned config)
+{
+	int i;
+	int ret = 0;
+	struct usb_gadget *gadget = dev->dev_gadget;
+	struct usb_ep *ep;
+	struct usb_request *req;
+	struct gs_req_entry *req_entry;
+
+	if (dev == NULL) {
+		printk(KERN_ERR "gs_set_config: NULL device pointer\n");
+		return 0;
+	}
+
+	if (config == dev->dev_config)
+		return 0;
+
+	gs_reset_config(dev);
+
+	if (config == GS_NO_CONFIG_ID)
+		return 0;
+
+	if (config != GS_BULK_CONFIG_ID)
+		return -EINVAL;
+
+	hw_optimize(gadget);
+
+	gadget_for_each_ep(ep, gadget) {
+
+		if (strcmp(ep->name, EP_IN_NAME) == 0) {
+			ret = usb_ep_enable(ep,
+				gadget->speed == USB_SPEED_HIGH ?
+ 				&gs_highspeed_in_desc : &gs_fullspeed_in_desc);
+			if (ret == 0) {
+				ep->driver_data = dev;
+				dev->dev_in_ep = ep;
+			} else {
+				printk(KERN_ERR "gs_set_config: cannot enable in endpoint %s, ret=%d\n",
+					ep->name, ret);
+				gs_reset_config(dev);
+				return ret;
+			}
+		}
+
+		else if (strcmp(ep->name, EP_OUT_NAME) == 0) {
+			ret = usb_ep_enable(ep,
+				gadget->speed == USB_SPEED_HIGH ?
+				&gs_highspeed_out_desc :
+				&gs_fullspeed_out_desc);
+			if (ret == 0) {
+				ep->driver_data = dev;
+				dev->dev_out_ep = ep;
+			} else {
+				printk(KERN_ERR "gs_set_config: cannot enable out endpoint %s, ret=%d\n",
+					ep->name, ret);
+				gs_reset_config(dev);
+				return ret;
+			}
+		}
+
+	}
+
+	if (dev->dev_in_ep == NULL || dev->dev_out_ep == NULL) {
+		gs_reset_config(dev);
+		printk(KERN_ERR "gs_set_config: cannot find endpoints\n");
+		return -ENODEV;
+	}
+
+	/* allocate and queue read requests */
+	ep = dev->dev_out_ep;
+	for (i=0; i<read_q_size && ret == 0; i++) {
+		if ((req=gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC))) {
+			req->complete = gs_read_complete;
+			if ((ret=usb_ep_queue(ep, req, GFP_ATOMIC))) {
+				printk(KERN_ERR "gs_set_config: cannot queue read request, ret=%d\n",
+					ret);
+			}
+		} else {
+			gs_reset_config(dev);
+			printk(KERN_ERR
+			"gs_set_config: cannot allocate read requests\n");
+			return -ENOMEM;
+		}
+	}
+
+	/* allocate write requests, and put on free list */
+	ep = dev->dev_in_ep;
+	for (i=0; i<write_q_size; i++) {
+		if ((req_entry=gs_alloc_req_entry(ep, ep->maxpacket, GFP_ATOMIC))) {
+			req_entry->re_req->complete = gs_write_complete;
+			list_add(&req_entry->re_entry, &dev->dev_req_list);
+		} else {
+			gs_reset_config(dev);
+			printk(KERN_ERR
+			"gs_set_config: cannot allocate write requests\n");
+			return -ENOMEM;
+		}
+	}
+
+	dev->dev_config = config;
+
+	printk(KERN_INFO "gs_set_config: %s configured for %s speed\n",
+		GS_LONG_NAME,
+		gadget->speed == USB_SPEED_HIGH ? "high" : "full");
+
+	return 0;
+}
+
+/*
+ * gs_reset_config
+ *
+ * Mark the device as not configured, disable all endpoints,
+ * which forces completion of pending I/O and frees queued
+ * requests, and free the remaining write requests on the
+ * free list.
+ *
+ * The device lock must be held when calling this function.
+ */
+static void gs_reset_config(struct gs_dev *dev)
+{
+	struct gs_req_entry *req_entry;
+
+	if (dev == NULL) {
+		printk(KERN_ERR "gs_reset_config: NULL device pointer\n");
+		return;
+	}
+
+	if (dev->dev_config == GS_NO_CONFIG_ID)
+		return;
+
+	dev->dev_config = GS_NO_CONFIG_ID;
+
+	/* free write requests on the free list */
+	while(!list_empty(&dev->dev_req_list)) {
+		req_entry = list_entry(dev->dev_req_list.next,
+			struct gs_req_entry, re_entry);
+		list_del(&req_entry->re_entry);
+		gs_free_req_entry(dev->dev_in_ep, req_entry);
+	}
+
+	/* disable endpoints, forcing completion of pending i/o; */
+	/* completion handlers free their requests in this case */
+	if (dev->dev_in_ep) {
+		usb_ep_disable(dev->dev_in_ep);
+		dev->dev_in_ep = NULL;
+	}
+	if (dev->dev_out_ep) {
+		usb_ep_disable(dev->dev_out_ep);
+		dev->dev_out_ep = NULL;
+	}
+}
+
+/*
+ * gs_build_config_desc
+ *
+ * Builds a config descriptor in the given buffer and returns the
+ * length, or a negative error number.
+ */
+static int gs_build_config_desc(u8 *buf, enum usb_device_speed speed, u8 type, unsigned int index)
+{
+	int high_speed;
+	int len = USB_DT_CONFIG_SIZE + USB_DT_INTERFACE_SIZE
+				+ GS_NUM_ENDPOINTS * USB_DT_ENDPOINT_SIZE;
+
+	/* only one config */
+	if (index != 0)
+		return -EINVAL;
+
+	memcpy(buf, &gs_config_desc, USB_DT_CONFIG_SIZE);
+	((struct usb_config_descriptor *)buf)->bDescriptorType = type;
+	((struct usb_config_descriptor *)buf)->wTotalLength = __constant_cpu_to_le16(len);
+	buf += USB_DT_CONFIG_SIZE;
+
+	memcpy(buf, &gs_interface_desc, USB_DT_INTERFACE_SIZE);
+	buf += USB_DT_INTERFACE_SIZE;
+
+	/* other speed switches high and full speed */
+	high_speed = (speed == USB_SPEED_HIGH);
+	if (type == USB_DT_OTHER_SPEED_CONFIG)
+		high_speed = !high_speed;
+
+	memcpy(buf,
+		high_speed ? &gs_highspeed_in_desc : &gs_fullspeed_in_desc,
+		USB_DT_ENDPOINT_SIZE);
+	buf += USB_DT_ENDPOINT_SIZE;
+	memcpy(buf,
+		high_speed ? &gs_highspeed_out_desc : &gs_fullspeed_out_desc,
+		USB_DT_ENDPOINT_SIZE);
+
+	return len;
+}
+
+/*
+ * gs_alloc_req
+ *
+ * Allocate a usb_request and its buffer.  Returns a pointer to the
+ * usb_request or NULL if there is an error.
+ */
+static struct usb_request *gs_alloc_req(struct usb_ep *ep, unsigned int len, int kmalloc_flags)
+{
+	struct usb_request *req;
+
+	if (ep == NULL)
+		return NULL;
+
+	req = usb_ep_alloc_request(ep, kmalloc_flags);
+
+	if (req != NULL) {
+		req->length = len;
+		req->buf = usb_ep_alloc_buffer(ep, len, &req->dma,
+			kmalloc_flags);
+		if (req->buf == NULL) {
+			usb_ep_free_request(ep, req);
+			return NULL;
+		}
+	}
+
+	return req;
+}
+
+/*
+ * gs_free_req
+ *
+ * Free a usb_request and its buffer.
+ */
+static void gs_free_req(struct usb_ep *ep, struct usb_request *req)
+{
+	if (ep != NULL && req != NULL) {
+		if (req->buf != NULL)
+			usb_ep_free_buffer(ep, req->buf, req->dma,
+				req->length);
+		usb_ep_free_request(ep, req);
+	}
+}
+
+/*
+ * gs_alloc_req_entry
+ *
+ * Allocates a request and its buffer, using the given
+ * endpoint, buffer len, and kmalloc flags.
+ */
+static struct gs_req_entry *gs_alloc_req_entry(struct usb_ep *ep, unsigned len, int kmalloc_flags)
+{
+	struct gs_req_entry	*req;
+
+	req = kmalloc(sizeof(struct gs_req_entry), kmalloc_flags);
+	if (req == NULL)
+		return NULL;
+
+	req->re_req = gs_alloc_req(ep, len, kmalloc_flags);
+	if (req->re_req == NULL) {
+		kfree(req);
+		return NULL;
+	}
+
+	req->re_req->context = req;
+
+	return req;
+}
+
+/*
+ * gs_free_req_entry
+ *
+ * Frees a request and its buffer.
+ */
+static void gs_free_req_entry(struct usb_ep *ep, struct gs_req_entry *req)
+{
+	if (ep != NULL && req != NULL) {
+		if (req->re_req != NULL)
+			gs_free_req(ep, req->re_req);
+		kfree(req);
+	}
+}
+
+/*
+ * gs_alloc_ports
+ *
+ * Allocate all ports and set the gs_dev struct to point to them.
+ * Return 0 if successful, or a negative error number.
+ *
+ * The device lock is normally held when calling this function.
+ */
+static int gs_alloc_ports(struct gs_dev *dev, int kmalloc_flags)
+{
+	int i;
+	struct gs_port *port;
+
+	if (dev == NULL)
+		return -EIO;
+
+	for (i=0; i<GS_NUM_PORTS; i++) {
+		if ((port=(struct gs_port *)kmalloc(sizeof(struct gs_port), kmalloc_flags)) == NULL)
+			return -ENOMEM;
+
+		memset(port, 0, sizeof(struct gs_port));
+		port->port_dev = dev;
+		port->port_num = i;
+		spin_lock_init(&port->port_lock);
+		init_waitqueue_head(&port->port_write_wait);
+
+		dev->dev_port[i] = port;
+	}
+
+	return 0;
+}
+
+/*
+ * gs_free_ports
+ *
+ * Free all closed ports.  Open ports are disconnected by
+ * freeing their write buffers, setting their device pointers
+ * and the pointers to them in the device to NULL.  These
+ * ports will be freed when closed.
+ *
+ * The device lock is normally held when calling this function.
+ */
+static void gs_free_ports(struct gs_dev *dev)
+{
+	int i;
+	unsigned long flags;
+	struct gs_port *port;
+
+	if (dev == NULL)
+		return;
+
+	for (i=0; i<GS_NUM_PORTS; i++) {
+		if ((port=dev->dev_port[i]) != NULL) {
+			dev->dev_port[i] = NULL;
+
+			spin_lock_irqsave(&port->port_lock, flags);
+
+			if (port->port_write_buf != NULL) {
+				gs_buf_free(port->port_write_buf);
+				port->port_write_buf = NULL;
+			}
+
+			if (port->port_open_count > 0 || port->port_in_use) {
+				port->port_dev = NULL;
+				wake_up_interruptible(&port->port_write_wait);
+				wake_up_interruptible(&port->port_tty->read_wait);
+				wake_up_interruptible(&port->port_tty->write_wait);
+			} else {
+				kfree(port);
+			}
+
+			spin_unlock_irqrestore(&port->port_lock, flags);
+		}
+	}
+}
+
+/* Circular Buffer */
+
+/*
+ * gs_buf_alloc
+ *
+ * Allocate a circular buffer and all associated memory.
+ */
+static struct gs_buf *gs_buf_alloc(unsigned int size, int kmalloc_flags)
+{
+	struct gs_buf *gb;
+
+	if (size == 0)
+		return NULL;
+
+	gb = (struct gs_buf *)kmalloc(sizeof(struct gs_buf), kmalloc_flags);
+	if (gb == NULL)
+		return NULL;
+
+	gb->buf_buf = kmalloc(size, kmalloc_flags);
+	if (gb->buf_buf == NULL) {
+		kfree(gb);
+		return NULL;
+	}
+
+	gb->buf_size = size;
+	gb->buf_get = gb->buf_put = gb->buf_buf;
+
+	return gb;
+}
+
+/*
+ * gs_buf_free
+ *
+ * Free the buffer and all associated memory.
+ */
+void gs_buf_free(struct gs_buf *gb)
+{
+	if (gb != NULL) {
+		if (gb->buf_buf != NULL)
+			kfree(gb->buf_buf);
+		kfree(gb);
+	}
+}
+
+/*
+ * gs_buf_clear
+ *
+ * Clear out all data in the circular buffer.
+ */
+void gs_buf_clear(struct gs_buf *gb)
+{
+	if (gb != NULL)
+		gb->buf_get = gb->buf_put;
+		/* equivalent to a get of all data available */
+}
+
+/*
+ * gs_buf_data_avail
+ *
+ * Return the number of bytes of data available in the circular
+ * buffer.
+ */
+unsigned int gs_buf_data_avail(struct gs_buf *gb)
+{
+	if (gb != NULL)
+		return (gb->buf_size + gb->buf_put - gb->buf_get) % gb->buf_size;
+	else
+		return 0;
+}
+
+/*
+ * gs_buf_space_avail
+ *
+ * Return the number of bytes of space available in the circular
+ * buffer.
+ */
+unsigned int gs_buf_space_avail(struct gs_buf *gb)
+{
+	if (gb != NULL)
+		return (gb->buf_size + gb->buf_get - gb->buf_put - 1) % gb->buf_size;
+	else
+		return 0;
+}
+
+/*
+ * gs_buf_put
+ *
+ * Copy data data from a user buffer and put it into the circular buffer.
+ * Restrict to the amount of space available.
+ *
+ * Return the number of bytes copied.
+ */
+unsigned int gs_buf_put(struct gs_buf *gb, const char *buf, unsigned int count)
+{
+	unsigned int len;
+
+	if (gb == NULL)
+		return 0;
+
+	len  = gs_buf_space_avail(gb);
+	if (count > len)
+		count = len;
+
+	if (count == 0)
+		return 0;
+
+	len = gb->buf_buf + gb->buf_size - gb->buf_put;
+	if (count > len) {
+		memcpy(gb->buf_put, buf, len);
+		memcpy(gb->buf_buf, buf+len, count - len);
+		gb->buf_put = gb->buf_buf + count - len;
+	} else {
+		memcpy(gb->buf_put, buf, count);
+		if (count < len)
+			gb->buf_put += count;
+		else /* count == len */
+			gb->buf_put = gb->buf_buf;
+	}
+
+	return count;
+}
+
+/*
+ * gs_buf_get
+ *
+ * Get data from the circular buffer and copy to the given buffer.
+ * Restrict to the amount of data available.
+ *
+ * Return the number of bytes copied.
+ */
+unsigned int gs_buf_get(struct gs_buf *gb, char *buf, unsigned int count)
+{
+	unsigned int len;
+
+	if (gb == NULL)
+		return 0;
+
+	len = gs_buf_data_avail(gb);
+	if (count > len)
+		count = len;
+
+	if (count == 0)
+		return 0;
+
+	len = gb->buf_buf + gb->buf_size - gb->buf_get;
+	if (count > len) {
+		memcpy(buf, gb->buf_get, len);
+		memcpy(buf+len, gb->buf_buf, count - len);
+		gb->buf_get = gb->buf_buf + count - len;
+	} else {
+		memcpy(buf, gb->buf_get, count);
+		if (count < len)
+			gb->buf_get += count;
+		else /* count == len */
+			gb->buf_get = gb->buf_buf;
+	}
+
+	return count;
+}