Here is version 0.20 of the garmin gps driver patch for review,
fixing the problems reported by oliver neukum.
 
Hermann Kneissel
 
diff -Naur linux-2.6.9/drivers/usb/serial/garmin_gps.c linux-2.6.9-gps/drivers/usb/serial/garmin_gps.c
--- linux-2.6.9/drivers/usb/serial/garmin_gps.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.9-gps/drivers/usb/serial/garmin_gps.c	2004-10-19 20:25:23.059968273 +0200
@@ -0,0 +1,1882 @@
+/*
+ * Garmin GPS driver
+ *
+ * Copyright (C) 2004 Hermann Kneissel [EMAIL PROTECTED]
+ *
+ * The latest version of the driver can be found at
+ * http://sourceforge.net/projects/garmin-gps/
+ *
+ * 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 USA
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/timer.h>
+#include <linux/tty.h>
+#include <linux/tty_driver.h>
+#include <linux/tty_flip.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <asm/uaccess.h>
+#include <linux/usb.h>
+
+#ifdef CONFIG_USB_SERIAL_DEBUG
+	static int debug = 1;
+#else
+	static int debug;
+#endif
+
+/* the mode to be set whenthe port ist opened */
+static int initial_mode = 1;
+
+#include "usb-serial.h"
+
+#define GARMIN_VENDOR_ID             0x091E
+
+/*
+ * Version Information
+ */
+
+#define VERSION_MAJOR	0
+#define VERSION_MINOR	20
+
+#define _STR(s) #s
+#define _DRIVER_VERSION(a,b) "v" _STR(a) "." _STR(b)
+#define DRIVER_VERSION _DRIVER_VERSION(VERSION_MAJOR, VERSION_MINOR)
+#define DRIVER_AUTHOR "hermann kneissel"
+#define DRIVER_DESC "garmin gps driver"
+
+/* debug flags */
+#define DEBUG_DRIVER	  0x0001
+#define DEBUG_QUEUE	  0x0002
+#define DEBUG_PROT_GSP    0x0010
+#define DEBUG_PROT_NATIVE 0x0040
+#define DEBUG_DATA_USB	  0x0100
+#define DEBUG_DATA_TTY	  0x0200
+#define DEBUG_DATA_GSP    0x0400
+
+/* error codes returned by the driver */
+#define EINVPKT	1000	/* invalid packet structure */
+
+
+
+struct garmin_data;
+
+/* function prototypes */
+static int  garmin_open(struct usb_serial_port *port, struct file *filp);
+static void garmin_close(struct usb_serial_port *port, struct file *filp);
+static int  garmin_write(struct usb_serial_port *port,
+			 int from_user, const unsigned char *buf, int count);
+static int  garmin_flush_queue(struct garmin_data * garmin_data_p);
+static int  garmin_write_room(struct usb_serial_port *port);
+static int  garmin_chars_in_buffer(struct usb_serial_port *port);
+static void garmin_throttle(struct usb_serial_port *port);
+static void garmin_unthrottle(struct usb_serial_port *port);
+static int  gpsmap_probe(struct usb_serial *serial,
+			 const struct usb_device_id *id);
+static void garmin_shutdown(struct usb_serial *serial);
+static int  garmin_ioctl(struct usb_serial_port *port, struct file * file,
+			 unsigned int cmd, unsigned long arg);
+static void garmin_set_termios(struct usb_serial_port *port,
+			       struct termios *old_termios);
+static void garmin_write_bulk_callback(struct urb *urb, struct pt_regs *regs);
+static void garmin_read_bulk_callback(struct urb *urb, struct pt_regs *regs);
+static void garmin_read_int_callback(struct urb *urb, struct pt_regs *regs);
+static int  garmin_attach(struct usb_serial *serial);
+static int  garmin_probe(struct usb_serial *serial,
+			 const struct usb_device_id *id);
+static int  garmin_write_bulk(struct usb_serial_port *port, int from_user,
+			     const unsigned char *buf, int count);
+static int  process_resetdev_request(struct usb_serial_port *port);
+static void gsp_next_packet(struct garmin_data * garmin_data_p);
+
+
+/* Parameters that may be passed into the module. */
+static int vendor  = -1;
+static int product = -1;
+
+/* some special packets to be send or received */
+static unsigned char const GARMIN_START_SESSION_REQ[]
+	= { 0, 0, 0, 0,  5, 0, 0, 0, 0, 0, 0, 0 };
+static unsigned char const GARMIN_START_SESSION_REQ2[]
+	= { 0, 0, 0, 0, 16, 0, 0, 0, 0, 0, 0, 0 };
+static unsigned char const GARMIN_START_SESSION_REPLY[]
+	= { 0, 0, 0, 0,  6, 0, 0, 0, 4, 0, 0, 0 };
+static unsigned char const GARMIN_SESSION_ACTIVE_REPLY[]
+	= { 0, 0, 0, 0, 17, 0, 0, 0, 4, 0, 0, 0, 0, 16, 0, 0 };
+static unsigned char const GARMIN_BULK_IN_AVAIL_REPLY[]
+	= { 0, 0, 0, 0,  2, 0, 0, 0, 0, 0, 0, 0 };
+static unsigned char const GARMIN_APP_LAYER_REPLY[]
+	= { 0x14, 0, 0, 0 };
+static unsigned char const GARMIN_START_PVT_REQ[]
+	= { 20, 0, 0, 0,  10, 0, 0, 0, 2, 0, 0, 0, 49, 0 };
+static unsigned char const GARMIN_STOP_PVT_REQ[]
+	= { 20, 0, 0, 0,  10, 0, 0, 0, 2, 0, 0, 0, 50, 0 };
+static unsigned char const GARMIN_STOP_TRANSFER_REQ[]
+	= { 20, 0, 0, 0,  10, 0, 0, 0, 2, 0, 0, 0, 0, 0 };
+static unsigned char const GARMIN_STOP_TRANSFER_REQ_V2[]
+	= { 20, 0, 0, 0,  10, 0, 0, 0, 1, 0, 0, 0, 0 };
+static unsigned char const PRIVATE_REQ[]
+	=    { 0x4B, 0x6E, 0x10, 0x01,  0xFF, 0, 0, 0, 0xFF, 0, 0, 0 };
+
+// size of a buffer able to hold a complete (incl. stuffing) packet
+#define GPSBUFSIZ 512
+// max. size of our private packets
+#define PRIVPKTSIZ 64
+
+#define GARMIN_LAYERID_TRANSPORT  0
+#define GARMIN_LAYERID_APPL      20
+// our own layer-id to use for some control mechanisms
+#define GARMIN_LAYERID_PRIVATE	0x01106E4B
+
+#define GARMIN_PKTID_PVT_DATA	51
+#define GARMIN_PKTID_L001_COMMAND_DATA 10
+
+#define CMND_ABORT_TRANSFER 0
+
+// packet ids used in private layer
+#define PRIV_PKTID_SET_DEBUG	1
+#define PRIV_PKTID_SET_MODE	2
+#define PRIV_PKTID_INFO_REQ	3
+#define PRIV_PKTID_INFO_RESP	4
+#define PRIV_PKTID_RESET_REQ	5
+#define PRIV_PKTID_SET_DEF_MODE	6
+
+#define GARMIN_PKTHDR_LENGTH	12
+
+#define ETX	0x03
+#define DLE	0x10
+#define ACK	0x06
+#define NAK	0x15
+
+
+
+static struct usb_device_id id_table [] = {
+	/* same device id for GPSmap60C and GPS18 */
+	{ USB_DEVICE(GARMIN_VENDOR_ID, 3 ),
+		.driver_info = (kernel_ulong_t)&gpsmap_probe },
+	{ },					/* optional parameter entry */
+	{ }					/* Terminating entry */
+};
+
+static struct usb_device_id id_table_combined [] = {
+	{ USB_DEVICE(GARMIN_VENDOR_ID, 3) },
+	{ },					/* optional parameter entry */
+	{ }					/* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE (usb, id_table_combined);
+
+static struct usb_driver garmin_driver = {
+	.owner =	THIS_MODULE,
+	.name =		"garmin_gps",
+	.probe =	usb_serial_probe,
+	.disconnect =	usb_serial_disconnect,
+	.id_table =	id_table_combined,
+};
+
+/* All of the device info needed */
+static struct usb_serial_device_type garmin_device = {
+	.owner               = THIS_MODULE,
+	.name                = "Garmin GPS usb/tty",
+	.short_name          = "garmin_gps",
+	.id_table            = id_table,
+	.num_interrupt_in    = 1,
+	.num_bulk_in         = 1,
+	.num_bulk_out        = 1,
+	.num_ports           = 1,
+	.open                = garmin_open,
+	.close               = garmin_close,
+	.throttle            = garmin_throttle,
+	.unthrottle          = garmin_unthrottle,
+	.attach              = garmin_attach,
+	.probe               = garmin_probe,
+	.shutdown            = garmin_shutdown,
+	.ioctl               = garmin_ioctl,
+	.set_termios         = garmin_set_termios,
+	.write               = garmin_write,
+	.write_room          = garmin_write_room,
+	.chars_in_buffer     = garmin_chars_in_buffer,
+	.write_bulk_callback = garmin_write_bulk_callback,
+	.read_bulk_callback  = garmin_read_bulk_callback,
+	.read_int_callback   = garmin_read_int_callback,
+};
+
+static int bytes_in;
+static int bytes_out;
+
+/* structure used to queue incoming packets */
+struct garmin_packet {
+	struct list_head  list;
+	int               seq;
+	int               size; // the real size of the data array, always > 0
+	__u8              data[1];
+};
+
+/* structure used to keep the current state of the driver */
+struct garmin_data {
+	__u8  state;
+	__u16 flags;
+	__u8  mode;
+	__u8  ignorePkts;
+	__u8  count;
+	__u8  pkt_id;
+	__u8  serial_num[4];
+	struct timer_list timer;
+	struct usb_serial_port *port;
+	int   seq_counter;
+	int   insize;
+	int   outsize;
+	__u8  inbuffer [GPSBUFSIZ]; /* tty -> usb */
+	__u8  outbuffer[GPSBUFSIZ]; /* usb -> tty */
+	spinlock_t lock;
+	struct list_head pktlist;
+};
+
+
+#define STATE_NEW            0
+#define STATE_INITIAL_DELAY  1
+#define STATE_TIMEOUT        2
+#define STATE_SESSION_REQ1   3
+#define STATE_SESSION_REQ2   4
+#define STATE_ACTIVE         5
+
+#define STATE_RESET	     8
+#define STATE_DISCONNECTED   9
+#define STATE_WAIT_TTY_ACK  10
+#define STATE_GSP_WAIT_DATA 11
+
+#define MODE_NATIVE          0
+#define MODE_GARMIN_SERIAL   1
+
+// Flags used in garmin_data.flags:
+#define FLAGS_SESSION_REPLY_MASK  0x00C0
+#define FLAGS_SESSION_REPLY1_SEEN 0x0080
+#define FLAGS_SESSION_REPLY2_SEEN 0x0040
+#define FLAGS_BULK_IN_ACTIVE      0x0020
+#define FLAGS_THROTTLED           0x0010
+#define CLEAR_HALT_REQUIRED       0x0001
+
+#define FLAGS_QUEUING             0x0100
+#define FLAGS_APP_RESP_SEEN       0x0200
+#define FLAGS_APP_REQ_SEEN        0x0400
+#define FLAGS_DROP_DATA           0x0800
+
+#define FLAGS_GSP_SKIP            0x1000
+#define FLAGS_GSP_DLESEEN         0x2000
+
+
+#undef dbg
+#define dbg_drv(garmin_data_p, format, arg...) \
+	do { \
+		if (debug&DEBUG_DRIVER) \
+			dev_printk(KERN_DEBUG, &garmin_data_p->port->dev, \
+				   format "\n" , ## arg); \
+	} while (0)
+
+#define dbg_gsp(garmin_data_p, format, arg...) \
+	do { \
+		if (debug&DEBUG_PROT_GSP) \
+	     		dev_printk(KERN_DEBUG, &garmin_data_p->port->dev, \
+				   format "\n", ## arg); \
+	} while (0)
+
+#define dbg_queue(garmin_data_p, format, arg...) \
+	do { \
+		if (debug&DEBUG_QUEUE) \
+			dev_printk(KERN_DEBUG, &garmin_data_p->port->dev, \
+				   format "\n", ## arg); \
+	} while (0)
+
+#define dbg_nat(garmin_data_p, format, arg...) \
+	do { \
+		if (debug&DEBUG_PROT_NATIVE) \
+			dev_printk(KERN_DEBUG, &garmin_data_p->port->dev, \
+				   format "\n" , ## arg); \
+	} while (0)
+
+static inline int garmin_debug_data(int debug,
+                                    struct device *dev,
+                                    const char *function,
+                                    int size,
+                                    const unsigned char *data)
+{
+	int i;
+
+	if (debug) {
+		dev_printk(KERN_DEBUG, dev,
+                   "%s - length = %d, data = ", function, size);
+		for (i = 0; i < size; ++i)
+			printk ("%.2x ", data[i]);
+		printk ("\n");
+	}
+	return debug;
+}
+
+
+static inline int get_int(const unsigned char *buf)
+{
+	return  (0xFF & buf[0]) | ((0xFF & buf[1]) << 8) |
+	        ((0xFF & buf[2]) << 16) | ((0xFF & buf[3]) << 24);
+}
+
+
+static inline int get_short(const unsigned char *buf)
+{
+	return  (0xFF & buf[0]) | ((0xFF & buf[1]) << 8);
+}
+
+
+static inline void set_int(unsigned char *buf, int value)
+{
+	buf[0] = 0xFF & value;
+	buf[1] = 0xFF & (value >> 8);
+	buf[2] = 0xFF & (value >> 16);
+	buf[3] = 0xFF & (value >> 24);
+}
+
+
+static inline int noResponseFromAppLayer(struct garmin_data * garmin_data_p)
+{
+	return ((garmin_data_p->flags
+				& (FLAGS_APP_REQ_SEEN|FLAGS_APP_RESP_SEEN))
+	        == FLAGS_APP_REQ_SEEN);
+}
+
+
+/*
+ * check if the usb-packet in buf contains an abort-transfer command.
+ * (if yes, all queued data will be dropped)
+ */
+static inline int isAbortTrfCmnd(const unsigned char *buf)
+{
+	if (0 == memcmp(buf, GARMIN_STOP_TRANSFER_REQ, 
+	                sizeof(GARMIN_STOP_TRANSFER_REQ)) ||
+	    0 == memcmp(buf, GARMIN_STOP_TRANSFER_REQ_V2, 
+	                sizeof(GARMIN_STOP_TRANSFER_REQ_V2)))
+		return 1;
+	else
+		return 0;
+}
+
+
+static struct list_head *list_first(struct list_head *head)
+{
+	return head->next;
+}
+
+
+
+static void send_to_tty(struct usb_serial_port *port,
+                        char *data, unsigned int actual_length)
+{
+	struct tty_struct *tty = port->tty;
+	int i;
+
+	if (tty && actual_length) {
+
+		garmin_debug_data (debug & DEBUG_DATA_TTY, &port->dev,
+		                   __FUNCTION__,
+		                   actual_length, data);
+
+		for (i = 0; i < actual_length ; ++i) {
+			/* if we insert more than TTY_FLIPBUF_SIZE characters,
+			   we drop them. */
+			if(tty->flip.count >= TTY_FLIPBUF_SIZE) {
+				tty_flip_buffer_push(tty);
+			}
+			/* this doesn't actually push the data through unless
+			   tty->low_latency is set */
+			tty_insert_flip_char(tty, data[i], 0);
+		}
+		tty_flip_buffer_push(tty);
+	}
+	bytes_in += actual_length;
+}
+
+
+/******************************************************************************
+ * packet queue handling
+ ******************************************************************************/
+
+/*
+ * queue a received (usb-)packet for later processing
+ */
+static int pkt_add(struct garmin_data * garmin_data_p,
+                   unsigned char *data, unsigned int data_length)
+{
+	int result = 0;
+	unsigned long flags;
+	struct garmin_packet *pkt;
+
+	/* process only packets containg data ... */
+	if (data_length) {
+		garmin_data_p->flags |= FLAGS_QUEUING;
+		pkt = kmalloc(sizeof(struct garmin_packet)+data_length,
+		              GFP_ATOMIC);
+		if (pkt == 0) {
+			dev_err(&garmin_data_p->port->dev, "out of memory\n");
+			return 0;
+		}
+		pkt->size = data_length;
+		memcpy(pkt->data, data, data_length);
+
+		spin_lock_irqsave(&garmin_data_p->lock, flags);
+		result = list_empty(&garmin_data_p->pktlist);
+		pkt->seq = garmin_data_p->seq_counter++;
+		list_add_tail(&pkt->list, &garmin_data_p->pktlist);
+		spin_unlock_irqrestore(&garmin_data_p->lock, flags);
+
+		/* in serial mode, if someone is waiting for data from
+		   the device, iconvert and send the next packet to tty. */
+		if (result && (garmin_data_p->state == STATE_GSP_WAIT_DATA)) {
+			gsp_next_packet(garmin_data_p);
+		}
+	}
+	return result;
+}
+
+
+/* get the next pending packet */
+static struct garmin_packet *pkt_pop(struct garmin_data * garmin_data_p)
+{
+	unsigned long flags;
+	struct garmin_packet *result = 0;
+
+	spin_lock_irqsave(&garmin_data_p->lock, flags);
+	if (!list_empty(&garmin_data_p->pktlist)) {
+		result = (struct garmin_packet *)
+			 list_first(&garmin_data_p->pktlist);
+		list_del(&result->list);
+	}
+	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
+	return result;
+}
+
+
+/* free up all queued data */
+static void pkt_clear(struct garmin_data * garmin_data_p)
+{
+	unsigned long flags;
+	struct garmin_packet *result = 0;
+
+	dbg_drv(garmin_data_p, "%s", __FUNCTION__);
+
+	spin_lock_irqsave(&garmin_data_p->lock, flags);
+	while (!list_empty(&garmin_data_p->pktlist)) {
+		result = (struct garmin_packet *)
+		         list_first(&garmin_data_p->pktlist);
+		list_del(&result->list);
+		kfree(result);
+	}
+	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
+}
+
+
+/******************************************************************************
+ * garmin serial protocol handling handling
+ ******************************************************************************/
+
+
+/* send a packet back to the tty */
+static int gsp_send_packet(struct garmin_data * garmin_data_p, __u8 pkt_id,
+                           unsigned data_length, unsigned char *data)
+{
+	__u8 pkt[512];
+	__u8 cksum = 0;
+	__u8 *ptr = pkt;
+	unsigned  l = 0;
+	unsigned  i = 0;
+
+	dbg_gsp(garmin_data_p,
+		"%s - pkt-id: 0x%X, %d bytes.", __FUNCTION__,
+		0xFF & pkt_id, data_length);
+
+	if (data_length && data_length < 256) {
+
+		*ptr++ = DLE;
+		*ptr++ = pkt_id;
+		cksum += pkt_id;
+
+		*ptr++ = data_length;
+		cksum += data_length;
+		if (data_length == DLE) {
+			*ptr++ = DLE;
+		}
+
+		while (i < data_length) {
+			*ptr++ = data[i];
+			cksum += data[i];
+			if (data[i] == DLE) {
+				*ptr++ = DLE;
+			}
+			i++;
+		}
+
+		*ptr++ = 0xff & (-cksum);
+		*ptr++ = DLE;
+		*ptr++ = ETX;
+
+		l = ptr-pkt;
+
+		send_to_tty(garmin_data_p->port, pkt, l);
+	}
+	return 0;
+}
+
+
+/* send an ack packet back to the tty */
+static int gsp_send_ack(struct garmin_data * garmin_data_p, __u8 pkt_id)
+{
+	__u8 pkt[2];
+
+	dbg_gsp(garmin_data_p,
+		"%s - pkt-id: 0x%X.", __FUNCTION__, 0xFF & pkt_id);
+
+	pkt[0] = pkt_id;
+	pkt[1] = 0;
+	return gsp_send_packet(garmin_data_p, ACK, 2, pkt);
+}
+
+
+
+/*
+ * called for a complete packet received from tty layer
+ * buf -> serial packet
+ */
+static int gsp_rec_packet(struct garmin_data * garmin_data_p,
+                          const unsigned char *buf, int count)
+{
+	__u8 usbpacket[512];
+	__u8 *data = usbpacket+GARMIN_PKTHDR_LENGTH;
+	int cksum = 0;
+	int i = 1;
+	int n = 0;
+	int size = buf[1];
+
+	garmin_debug_data (debug & DEBUG_DATA_GSP, &garmin_data_p->port->dev,
+			   __FUNCTION__, count, buf);
+
+	set_int(usbpacket, GARMIN_LAYERID_APPL);
+	set_int(usbpacket+4, buf[0]);
+	set_int(usbpacket+8, buf[1]);
+
+	cksum += buf[0]; // id
+	cksum += buf[1]; // len
+	i++;
+
+	while (n < size) {
+		if (i >= count) {
+			dbg_gsp(garmin_data_p,
+				"%s - packet too small, "
+			        "expected %d byte, got %d",
+				__FUNCTION__, size, count);
+			return -EINVPKT;
+		}
+		*data++ = buf[i];
+		cksum += buf[i];
+		i++;
+		n++;
+	}
+
+	garmin_write_bulk (garmin_data_p->port, 0, usbpacket,
+			   GARMIN_PKTHDR_LENGTH+size);
+
+	/* if this was an abort-transfer command, flush all
+	   queued data. */
+	if (isAbortTrfCmnd(usbpacket)) {
+		garmin_data_p->flags |= FLAGS_DROP_DATA;
+		pkt_clear(garmin_data_p);
+	}
+
+	return count;
+}
+
+
+
+/*
+ * Called for data received from tty
+ *
+ * buf contains the datas read, it may span more than one packet or even
+ * incomplete packets
+ *
+ * input record should be a serial-record, but it may not be complete.
+ * Copy it into our local buffer, until an etx is seen (or an error
+ * occurs).
+ * Once the record is complete, convert into a usb packet and send it
+ * to the bulk pipe, send an ack back to the tty.
+ *
+ * If the input is an ack, just send the last queued packet to the
+ * tty layer.
+ *
+ * if the input is an abort command, drop all queued data.
+ */
+
+static int gsp_receive(struct garmin_data * garmin_data_p,
+                       int from_user, const unsigned char *buf, int count)
+{
+	__u8 buffer[GPSBUFSIZ];
+	int offs = 0;
+	int ack_or_nak_seen = 0;
+	int i,len;
+	__u8 *dest = garmin_data_p->inbuffer;
+	int size = garmin_data_p->insize;
+	int dleSeen = garmin_data_p->flags & FLAGS_GSP_DLESEEN;
+	int skip = garmin_data_p->flags & FLAGS_GSP_SKIP;
+
+	dbg_gsp(garmin_data_p,
+		"%s - dle=%d skip=%d size=%d count=%d",
+		__FUNCTION__, dleSeen, skip, size, count);
+
+	while (offs < count) {
+		len = GPSBUFSIZ;
+		if ((offs+len) > count)
+			len = count-offs;
+
+		if (from_user) {
+			if (copy_from_user(buffer, buf+offs, len))
+				return -EFAULT;
+		} else {
+			memcpy(buffer, buf+offs, len);
+		}
+		offs += len;
+
+		i=0;
+		while (i < len) {
+			if (buffer[i] == DLE) {
+				if (skip) { /* start of a new pkt */
+					skip = 0;
+					size = 0;
+					dleSeen = 1;
+				} else if (dleSeen) {
+					dest[size++] = buffer[i];
+					dleSeen = 0;
+				} else {
+					dleSeen = 1;
+				}
+			} else if (buffer[i] == ETX) {
+				if (dleSeen) {
+					/* packet complete */
+					if (dest[0] == ACK) {
+						ack_or_nak_seen = ACK;
+						dbg_gsp(garmin_data_p,
+						"ACK packet complete.");
+					} else if (dest[0] == NAK) {
+						ack_or_nak_seen = NAK;
+						dbg_gsp(garmin_data_p,
+						"NAK packet complete.");
+					} else {
+						dbg_gsp(garmin_data_p,
+							"packet complete "
+						        "- id=0x%X.",
+						        0xFF & dest[0]);
+						gsp_rec_packet(garmin_data_p,
+							       dest,
+						               size);
+					}
+
+					skip = 1;
+					size = 0;
+					dleSeen = 0;
+				} else {
+					dest[size++] = buffer[i];
+				}
+			} else if (!skip) {
+
+				if (dleSeen) {
+					dbg_gsp(garmin_data_p,
+						"non-masked DLE at %d"
+					        " - restarting", i);
+					size = 0;
+					dleSeen = 0;
+				}
+
+				dest[size++] = buffer[i];
+			}
+
+			if (size >= GPSBUFSIZ) {
+				dbg_gsp(garmin_data_p,
+					"%s - packet too large.", __FUNCTION__);
+				skip = 1;
+				size = 0;
+				dleSeen = 0;
+			}
+
+			i++;
+		}
+	}
+
+	garmin_data_p->insize = size;
+
+	// copy flags back to structure
+	if (skip)
+		garmin_data_p->flags |= FLAGS_GSP_SKIP;
+	else
+		garmin_data_p->flags &= ~FLAGS_GSP_SKIP;
+
+	if (dleSeen)
+		garmin_data_p->flags |= FLAGS_GSP_DLESEEN;
+	else
+		garmin_data_p->flags &= ~FLAGS_GSP_DLESEEN;
+
+	if (ack_or_nak_seen) {
+		garmin_data_p->state = STATE_GSP_WAIT_DATA;
+		gsp_next_packet(garmin_data_p);
+	}
+
+	return count;
+}
+
+
+
+
+/*
+ * Sends a usb packet to the tty
+ *
+ * Assumes, that all packages and at an usb-packet boundary.
+ *
+ * return -1 on error, 0 if packet is incomplete or > 0 if packet was sent
+ */
+int gsp_send(struct garmin_data * garmin_data_p, const unsigned char *buf,
+              int count)
+{
+	char buffer[GPSBUFSIZ];
+	int cksum = 0;
+	int i=0;
+	int k;
+	int len;
+
+	dbg_gsp(garmin_data_p,
+		"%s - state %d - %d bytes.", __FUNCTION__,
+	         garmin_data_p->state, count);
+
+	len = garmin_data_p->outsize;
+	if ((len+count) > GPSBUFSIZ) {
+		dbg_gsp(garmin_data_p, "packet too large");
+		garmin_data_p->outsize = 0;
+		return -4;
+	}
+
+	memcpy(garmin_data_p->outbuffer+len, buf, count);
+	len += count;
+	garmin_data_p->outsize = len;
+
+	if (len >= GARMIN_PKTHDR_LENGTH) {
+		k = GARMIN_PKTHDR_LENGTH + (garmin_data_p->outbuffer[8] & 0xff);
+		if (len < k)
+			return 0;
+	}
+
+	garmin_data_p->outsize = 0;
+	buf = garmin_data_p->outbuffer;
+	count = len;
+
+	if (debug & DEBUG_DATA_GSP)
+		garmin_debug_data (1, &garmin_data_p->port->dev, __FUNCTION__,
+		                   len, buf);
+	else
+		dbg_gsp(garmin_data_p,
+			"%s - pkt id=0x%x complete.", __FUNCTION__,
+		        get_int(buf+4));
+
+	if (GARMIN_LAYERID_APPL != get_int(buf)) {
+		dbg_gsp(garmin_data_p,
+			"not an application packet (%d)", get_int(buf));
+		return -1;
+	}
+
+	if (get_int(buf+4) > 255) {
+		dbg_gsp(garmin_data_p,
+			"packet-id %d too large", get_int(buf+4));
+		return -2;
+	}
+
+	if (get_int(buf+8) > 255) {
+		dbg_gsp(garmin_data_p,
+			"packet-size %d too large", get_int(buf+8));
+		return -3;
+	}
+
+	if (buf[4] == 0xFD) {
+	}
+
+	buffer[i++] = DLE;
+	buffer[i++] = buf[4];
+	cksum += buf[4];
+	len = 0xFF & buf[8];
+	buffer[i++] = len;
+	cksum += len;
+	if (len == DLE)
+	  buffer[i++] = DLE;
+
+	len += GARMIN_PKTHDR_LENGTH;
+	for (k=GARMIN_PKTHDR_LENGTH; k<len; k++) {
+		buffer[i++] = buf[k];
+		cksum += buf[k];
+		if (buf[k] == DLE)
+			buffer[i++] = DLE;
+	}
+
+	cksum = 0xFF & -cksum;
+	buffer[i++] = cksum;
+	if (cksum == DLE)
+		buffer[i++] = DLE;
+	buffer[i++] = DLE;
+	buffer[i++] = ETX;
+
+	send_to_tty(garmin_data_p->port, buffer, i);
+
+	garmin_data_p->pkt_id = buf[4];
+	garmin_data_p->state  = STATE_WAIT_TTY_ACK;
+
+	return i;
+}
+
+
+
+
+
+/*
+ * Process the next pending data packet - if there is one
+ */
+static void gsp_next_packet(struct garmin_data * garmin_data_p)
+{
+	struct garmin_packet *pkt = 0;
+
+	while ((pkt = pkt_pop(garmin_data_p)) != 0)
+	{
+		dbg_queue(garmin_data_p,
+			  "%s - next pkt: %d", __FUNCTION__, pkt->seq);
+		if (gsp_send(garmin_data_p, pkt->data, pkt->size) > 0) {
+			kfree(pkt);
+			return;
+		}
+		kfree(pkt);
+	}
+}
+
+
+
+
+/******************************************************************************
+ * garmin native mode
+ ******************************************************************************/
+
+
+/*
+ * Called for data received from tty
+ *
+ * The input data is expected to be in garmin usb-packet format.
+ *
+ * buf contains the datas read, it may span more than one packet
+ * or even incomplete packets
+ */
+static int nat_receive(struct garmin_data * garmin_data_p,
+                       int from_user,
+                       const unsigned char *buf, int count)
+{
+	__u8 * dest;
+	int offs = 0;
+	int result = count;
+	int len;
+
+	while (offs < count) {
+		// if buffer contains header, copy rest of data
+		if (garmin_data_p->insize >= GARMIN_PKTHDR_LENGTH)
+			len = GARMIN_PKTHDR_LENGTH
+			      +get_int(garmin_data_p->inbuffer+8);
+		else
+			len = GARMIN_PKTHDR_LENGTH;
+
+		if (len >= GPSBUFSIZ) {
+			/* seem to be an invalid packet, ignore rest of input */
+			dbg_nat(garmin_data_p,
+				"%s - packet size too large: %d",
+			        __FUNCTION__, len);
+			garmin_data_p->insize = 0;
+			count = 0;
+			result = -EINVPKT;
+		} else {
+			len -= garmin_data_p->insize;
+			if (len > (count-offs))
+				len = (count-offs);
+			if (len > 0) {
+				dest = garmin_data_p->inbuffer
+				       	+garmin_data_p->insize;
+				if (from_user) {
+					if (copy_from_user(dest, buf+offs, len))
+						return -EFAULT;
+
+				} else {
+					memcpy(dest, buf+offs, len);
+				}
+				garmin_data_p->insize += len;
+				offs += len;
+			}
+		}
+
+		/* do we have a complete packet ? */
+		if (garmin_data_p->insize >= GARMIN_PKTHDR_LENGTH) {
+			len = GARMIN_PKTHDR_LENGTH+
+				get_int(garmin_data_p->inbuffer+8);
+			if (garmin_data_p->insize >= len) {
+				garmin_write_bulk (garmin_data_p->port, 0,
+				                   garmin_data_p->inbuffer,
+				                   len);
+				garmin_data_p->insize = 0;
+
+				/* if this was an abort-transfer command,
+				   flush all queued data. */
+				if (isAbortTrfCmnd(garmin_data_p->inbuffer)) {
+					garmin_data_p->flags |= FLAGS_DROP_DATA;
+					pkt_clear(garmin_data_p);
+				}
+			}
+		}
+	}
+	return result;
+}
+
+
+/******************************************************************************
+ * private packets
+ ******************************************************************************/
+
+static void priv_status_resp(struct usb_serial_port *port)
+{
+	struct garmin_data * garmin_data_p =
+		(struct garmin_data *) usb_get_serial_port_data(port);
+	__u8 pkt[GARMIN_PKTHDR_LENGTH+12];
+
+	set_int(pkt, GARMIN_LAYERID_PRIVATE);
+	set_int(pkt+4, PRIV_PKTID_INFO_RESP);
+	set_int(pkt+8, 12);
+	set_int(pkt+12, VERSION_MAJOR << 16 | VERSION_MINOR);
+	set_int(pkt+16, garmin_data_p->mode);
+	memcpy(pkt+20, garmin_data_p->serial_num, 4);
+
+	send_to_tty(port, pkt, sizeof(pkt));
+}
+
+
+/******************************************************************************
+ * Timer callback
+ ******************************************************************************/
+
+static void timeout_handler(unsigned long data)
+{
+	struct garmin_data *garmin_data_p = (struct garmin_data *) data;
+
+	/* send the next queued packet to the tty port */
+	if (garmin_data_p->mode == MODE_NATIVE)
+		if (garmin_data_p->flags & FLAGS_QUEUING)
+			garmin_flush_queue(garmin_data_p);
+}
+
+/******************************************************************************
+ * Garmin specific driver functions
+ ******************************************************************************/
+
+/*
+ * clear all cached data
+ */
+static int garmin_clear(struct garmin_data * garmin_data_p)
+{
+	int status = 0;
+
+	struct usb_serial_port *port = garmin_data_p->port;
+
+	if (port != 0 && garmin_data_p->flags & FLAGS_APP_RESP_SEEN) {
+		/* send a terminate command */
+		status = garmin_write_bulk(port, 0, GARMIN_STOP_TRANSFER_REQ,
+		                           sizeof(GARMIN_STOP_TRANSFER_REQ));
+	}
+
+	/* flush all queued data */
+	pkt_clear(garmin_data_p);
+
+	garmin_data_p->insize = 0;
+	garmin_data_p->outsize = 0;
+
+	return status;
+}
+
+
+
+
+
+
+static int garmin_init_session(struct usb_serial_port *port)
+{
+	struct usb_serial *serial = port->serial;
+	struct garmin_data * garmin_data_p =
+		(struct garmin_data *) usb_get_serial_port_data(port);
+	int status = 0;
+
+	if (status == 0) {
+		usb_unlink_urb (port->interrupt_in_urb);
+
+		dbg_drv(garmin_data_p,
+			"%s - adding interrupt input", __FUNCTION__);
+		port->interrupt_in_urb->dev = serial->dev;
+		status = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
+		if (status)
+			dev_err(&serial->dev->dev,
+			        "%s - failed submitting interrupt urb,"
+				" error %d\n",
+			        __FUNCTION__, status);
+	}
+
+	if (status == 0) {
+		dbg_drv(garmin_data_p,
+			"%s - starting session ...", __FUNCTION__);
+		garmin_data_p->state = STATE_ACTIVE;
+		status = garmin_write_bulk(port, 0, GARMIN_START_SESSION_REQ,
+		                           sizeof(GARMIN_START_SESSION_REQ));
+
+		if (status >= 0) {
+
+			garmin_data_p->ignorePkts++;
+
+			/* not needed, but the win32 driver does it too ... */
+			status = garmin_write_bulk(port, 0,
+						   GARMIN_START_SESSION_REQ2,
+			                           sizeof(GARMIN_START_SESSION_REQ2));
+			if (status >= 0) {
+				status = 0;
+				garmin_data_p->ignorePkts++;
+			}
+		}
+	}
+
+	return status;
+}
+
+
+
+
+
+static int garmin_open (struct usb_serial_port *port, struct file *filp)
+{
+	int status = 0;
+	struct garmin_data * garmin_data_p
+		= (struct garmin_data *) usb_get_serial_port_data(port);
+
+	dbg_drv(garmin_data_p,
+		"%s - port %d", __FUNCTION__, port->number);
+
+	bytes_in = 0;
+	bytes_out = 0;
+
+	/*
+	 * Force low_latency on so that our tty_push actually forces the data
+	 * through, otherwise it is scheduled, and with high data rates (like
+	 * with OHCI) data can get lost.
+	 */
+	if (port->tty)
+		port->tty->low_latency = 1;
+
+	garmin_data_p->mode  = initial_mode;
+	garmin_data_p->count = 0;
+	garmin_data_p->flags = 0;
+
+	/* shutdown any bulk reads that might be going on */
+	usb_unlink_urb (port->write_urb);
+	usb_unlink_urb (port->read_urb);
+
+	if (garmin_data_p->state == STATE_RESET) {
+		status = garmin_init_session(port);
+	}
+
+	garmin_data_p->state = STATE_ACTIVE;
+
+	return status;
+}
+
+
+static void garmin_close (struct usb_serial_port *port, struct file * filp)
+{
+	int status;
+	struct usb_serial *serial = port->serial;
+	struct garmin_data * garmin_data_p
+		= (struct garmin_data *) usb_get_serial_port_data(port);
+
+	dbg_drv(garmin_data_p,
+		"%s - port %d - mode=%d state=%d flags=0x%X", __FUNCTION__,
+		port->number, garmin_data_p->mode,
+		garmin_data_p->state, garmin_data_p->flags);
+
+	if (!serial)
+		return;
+
+	garmin_clear(garmin_data_p);
+
+	/* shutdown our urbs */
+	status = usb_unlink_urb (port->read_urb);
+	if (status)
+		dbg_drv(garmin_data_p,
+			"%s - port %d - error %d during unlink read_urb",
+			__FUNCTION__, port->number, status);
+
+	status = usb_unlink_urb (port->write_urb);
+	if (status)
+		dbg_drv(garmin_data_p,
+			"%s - port %d - error %d during unlink write_urb",
+			__FUNCTION__, port->number, status);
+
+	if (noResponseFromAppLayer(garmin_data_p) ||
+	    ((garmin_data_p->flags & CLEAR_HALT_REQUIRED) != 0)) {
+		process_resetdev_request(port);
+		garmin_data_p->state = STATE_RESET;
+	} else {
+		garmin_data_p->state = STATE_DISCONNECTED;
+	}
+
+	/* Uncomment the following line if you want to see some statistics
+	   in your syslog
+	dev_info (&port->dev, "Bytes In = %d  Bytes Out = %d\n",
+	          bytes_in, bytes_out);
+	*/
+}
+
+
+static int process_resetdev_request(struct usb_serial_port *port)
+{
+	int status;
+	struct garmin_data * garmin_data_p
+		= (struct garmin_data *) usb_get_serial_port_data(port);
+
+	garmin_data_p->flags &= ~(CLEAR_HALT_REQUIRED);
+	garmin_data_p->state = STATE_RESET;
+	memset(garmin_data_p->serial_num, 0, 4);
+
+	usb_unlink_urb (port->interrupt_in_urb);
+	dbg_drv(garmin_data_p, "%s - usb_reset_device", __FUNCTION__ );
+	status = usb_reset_device(port->serial->dev);
+	if (status)
+		dbg_drv(garmin_data_p,
+			"%s - usb_reset_device failed: %d",
+			__FUNCTION__, status);
+	return status;
+}
+
+
+
+static int garmin_write_bulk (struct usb_serial_port *port, int from_user,
+                              const unsigned char *buf, int count)
+{
+	struct usb_serial *serial = port->serial;
+	struct garmin_data * garmin_data_p
+		= (struct garmin_data *) usb_get_serial_port_data(port);
+	struct urb *urb;
+	unsigned char *buffer;
+	int status;
+
+	dbg_drv(garmin_data_p,
+		"%s - port %d, state %d", __FUNCTION__, port->number,
+		garmin_data_p->state);
+
+	garmin_data_p->flags &= ~FLAGS_DROP_DATA;
+
+	buffer = kmalloc (count, GFP_ATOMIC);
+	if (!buffer) {
+		dev_err(&port->dev, "out of memory\n");
+		return -ENOMEM;
+	}
+
+	urb = usb_alloc_urb(0, GFP_ATOMIC);
+	if (!urb) {
+		dev_err(&port->dev, "no more free urbs\n");
+		kfree (buffer);
+		return -ENOMEM;
+	}
+
+	if (from_user) {
+		if (copy_from_user (buffer, buf, count)) {
+			kfree (buffer);
+			usb_free_urb (urb);
+			return -EFAULT;
+		}
+	} else {
+		memcpy (buffer, buf, count);
+	}
+
+	garmin_debug_data (debug & DEBUG_DATA_USB, &port->dev, __FUNCTION__,
+	                   count, buffer);
+
+	usb_fill_bulk_urb (urb, serial->dev,
+			 	usb_sndbulkpipe (serial->dev,
+				port->bulk_out_endpointAddress),
+				buffer, count,
+				garmin_write_bulk_callback, port);
+	urb->transfer_flags |= URB_ZERO_PACKET;
+
+	if (GARMIN_LAYERID_APPL == get_int(buffer)) {
+		garmin_data_p->flags |= FLAGS_APP_REQ_SEEN;
+		if (garmin_data_p->mode == MODE_GARMIN_SERIAL)  {
+			pkt_clear(garmin_data_p);
+			garmin_data_p->state = STATE_GSP_WAIT_DATA;
+		}
+	}
+
+	/* send it down the pipe */
+	status = usb_submit_urb(urb, GFP_ATOMIC);
+	if (status) {
+		dev_err(&port->dev,
+		        "%s - usb_submit_urb(write bulk) "
+		        "failed with status = %d\n",
+				__FUNCTION__, status);
+		count = status;
+	} else {
+
+		if (GARMIN_LAYERID_APPL == get_int(buffer)
+		    && (garmin_data_p->mode == MODE_GARMIN_SERIAL))  {
+
+			gsp_send_ack(garmin_data_p, buffer[4]);
+		}
+
+		bytes_out += count;
+	}
+
+	/* we are done with this urb, so let the host driver
+	 * really free it when it is finished with it */
+	usb_free_urb (urb);
+
+	return count;
+}
+
+
+
+static int garmin_write (struct usb_serial_port *port, int from_user,
+                         const unsigned char *buf, int count)
+{
+	__u8 privpkt[PRIVPKTSIZ];
+	int pktid, pktsiz, len;
+	struct garmin_data * garmin_data_p =
+		(struct garmin_data *) usb_get_serial_port_data(port);
+
+	dbg_drv(garmin_data_p,
+		"%s - port %d, state %d, mode %d", __FUNCTION__,
+	    	port->number, garmin_data_p->state, garmin_data_p->mode);
+
+	garmin_debug_data (debug & DEBUG_DATA_TTY, &port->dev, __FUNCTION__,
+	                   count, buf);
+
+	/* check for our private packets */
+	if (count >= GARMIN_PKTHDR_LENGTH) {
+
+		len = PRIVPKTSIZ;
+		if (count < len)
+			len = count;
+
+		if (from_user) {
+			if (copy_from_user(privpkt, buf, len))
+				return -EFAULT;
+		} else {
+			memcpy(privpkt, buf, len);
+		}
+
+		pktsiz = get_int(privpkt+8);
+
+		if (count == (GARMIN_PKTHDR_LENGTH+pktsiz)
+				&& GARMIN_LAYERID_PRIVATE == get_int(privpkt)) {
+
+			pktid = get_int(privpkt+4);
+			dbg_drv(garmin_data_p,
+				"%s - processing private request %d",
+				__FUNCTION__, pktid);
+
+			// drop all unfinished transfers
+			garmin_clear(garmin_data_p);
+
+			switch(pktid) {
+
+			case PRIV_PKTID_SET_DEBUG:
+				if (pktsiz != 4)
+					return -EINVPKT;
+				debug = get_int(privpkt+12);
+				dbg_drv(garmin_data_p,
+					"%s - debug level set to 0x%X",
+					__FUNCTION__, debug);
+				break;
+
+			case PRIV_PKTID_SET_MODE:
+				if (pktsiz != 4)
+					return -EINVPKT;
+				garmin_data_p->mode = get_int(privpkt+12);
+				dbg_drv(garmin_data_p,
+					"%s - mode set to %d",
+					__FUNCTION__, garmin_data_p->mode);
+				break;
+
+			case PRIV_PKTID_INFO_REQ:
+				priv_status_resp(port);
+				break;
+
+			case PRIV_PKTID_RESET_REQ:
+				garmin_data_p->flags |= FLAGS_APP_REQ_SEEN;
+				break;
+
+			case PRIV_PKTID_SET_DEF_MODE:
+				if (pktsiz != 4)
+					return -EINVPKT;
+				initial_mode = get_int(privpkt+12);
+				dbg_drv(garmin_data_p,
+					"%s - initial_mode set to %d",
+					__FUNCTION__,
+					garmin_data_p->mode);
+				break;
+			}
+			return count;
+		}
+	}
+
+	if (garmin_data_p->mode == MODE_GARMIN_SERIAL) {
+
+		return gsp_receive(garmin_data_p, from_user, buf, count);
+
+	} else {	/* MODE_NATIVE */
+
+		return nat_receive(garmin_data_p, from_user, buf, count);
+		//return garmin_write_bulk(port, from_user, buf, count);
+	}
+}
+
+
+static int garmin_write_room (struct usb_serial_port *port)
+{
+	/*
+	 * We really can take anything the user throws at us
+	 * but let's pick a nice big number to tell the tty
+	 * layer that we have lots of free space
+	 */
+	return 2048;
+}
+
+
+static int garmin_chars_in_buffer (struct usb_serial_port *port)
+{
+	/*
+	 * We can't really account for how much data we
+	 * have sent out, but hasn't made it through to the
+	 * device, so just tell the tty layer that everything
+	 * is flushed.
+	 */
+	return 0;
+}
+
+
+static void garmin_write_bulk_callback (struct urb *urb, struct pt_regs *regs)
+{
+	struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
+	struct garmin_data * garmin_data_p
+		= (struct garmin_data *) usb_get_serial_port_data(port);
+
+	/* free up the transfer buffer, as usb_free_urb() does not do this */
+	kfree (urb->transfer_buffer);
+
+	dbg_drv(garmin_data_p, "%s - port %d", __FUNCTION__, port->number);
+
+	if (urb->status) {
+		dbg_drv(garmin_data_p,
+			"%s - nonzero write bulk status received: %d",
+			__FUNCTION__, urb->status);
+		garmin_data_p->flags |= CLEAR_HALT_REQUIRED;
+	}
+
+	schedule_work(&port->work);
+}
+
+
+static void garmin_read_bulk_callback (struct urb *urb, struct pt_regs *regs)
+{
+	struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
+	struct usb_serial *serial =  port->serial;
+	unsigned char *data = urb->transfer_buffer;
+	struct garmin_data * garmin_data_p
+		= (struct garmin_data *) usb_get_serial_port_data(port);
+	int status;
+
+	dbg_drv(garmin_data_p, "%s - port %d", __FUNCTION__, port->number);
+
+	if (!serial) {
+		dbg_drv(garmin_data_p,
+			"%s - bad serial pointer, exiting", __FUNCTION__);
+		return;
+	}
+
+	if (urb->status) {
+		dbg_drv(garmin_data_p,
+			"%s - nonzero read bulk status received: %d",
+			__FUNCTION__, urb->status);
+		return;
+	}
+
+	garmin_debug_data (debug & DEBUG_DATA_USB, &port->dev, __FUNCTION__,
+	                   urb->actual_length, data);
+
+	send_to_tty(port, data, urb->actual_length);
+
+	/* Continue trying to read until nothing more is received  */
+	if (urb->actual_length > 0) {
+		usb_fill_bulk_urb (port->read_urb, serial->dev,
+			   usb_rcvbulkpipe (serial->dev,
+					    port->bulk_in_endpointAddress),
+			   port->read_urb->transfer_buffer,
+			   port->read_urb->transfer_buffer_length,
+			   garmin_read_bulk_callback, port);
+		status = usb_submit_urb(port->read_urb, GFP_ATOMIC);
+		if (status)
+			dev_err(&port->dev,
+				"%s - failed resubmitting read urb, error %d\n",
+			        __FUNCTION__, status);
+	}
+	return;
+}
+
+static void garmin_read_int_callback (struct urb *urb, struct pt_regs *regs)
+{
+	int status;
+	struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
+	struct usb_serial *serial = port->serial;
+	struct garmin_data * garmin_data_p
+		= (struct garmin_data *) usb_get_serial_port_data(port);
+	unsigned char *data = urb->transfer_buffer;
+
+	switch (urb->status) {
+	case 0:
+		/* success */
+		break;
+	case -ECONNRESET:
+	case -ENOENT:
+	case -ESHUTDOWN:
+		/* this urb is terminated, clean up */
+		dbg_drv(garmin_data_p, "%s - urb shutting down with status: %d",
+			__FUNCTION__, urb->status);
+		return;
+	default:
+		dbg_drv(garmin_data_p, "%s - nonzero urb status received: %d",
+			__FUNCTION__, urb->status);
+		return;
+	}
+
+	garmin_debug_data (debug & DEBUG_DATA_USB, &port->dev, __FUNCTION__,
+	                   urb->actual_length, urb->transfer_buffer);
+
+	if (urb->actual_length == sizeof(GARMIN_BULK_IN_AVAIL_REPLY) &&
+	    0 == memcmp(data, GARMIN_BULK_IN_AVAIL_REPLY,
+		        sizeof(GARMIN_BULK_IN_AVAIL_REPLY))) {
+
+		dbg_drv(garmin_data_p,
+			"%s - bulk data available.", __FUNCTION__);
+
+		/* bulk data available */
+		usb_fill_bulk_urb (port->read_urb, serial->dev,
+				usb_rcvbulkpipe (serial->dev,
+				port->bulk_in_endpointAddress),
+				port->read_urb->transfer_buffer,
+				port->read_urb->transfer_buffer_length,
+				garmin_read_bulk_callback, port);
+		status = usb_submit_urb(port->read_urb, GFP_KERNEL);
+		if (status) {
+			dev_err(&port->dev,
+				"%s - failed submitting read urb, error %d\n",
+			__FUNCTION__, status);
+		}
+
+	} else if (urb->actual_length == (4+sizeof(GARMIN_START_SESSION_REPLY))
+			 && 0 == memcmp(data, GARMIN_START_SESSION_REPLY,
+			                sizeof(GARMIN_START_SESSION_REPLY))) {
+
+		garmin_data_p->flags |= FLAGS_SESSION_REPLY1_SEEN;
+		/* save the serial number */
+		memcpy(garmin_data_p->serial_num, data+GARMIN_PKTHDR_LENGTH, 4);
+		dbg_drv(garmin_data_p,
+			"%s - start-of-session reply seen - serial %u.",
+			__FUNCTION__, get_int(garmin_data_p->serial_num));
+
+	}
+
+	if (garmin_data_p->ignorePkts) {
+		/* this reply belongs to a request generated by the driver,
+		   ignore it. */
+		dbg_drv(garmin_data_p,
+			"%s - pkt ignored (%d)",
+			__FUNCTION__, garmin_data_p->ignorePkts);
+		garmin_data_p->ignorePkts--;
+	} else if (garmin_data_p->flags & FLAGS_DROP_DATA) {
+		/* abort-transfer cmd is actice */
+		dbg_drv(garmin_data_p,
+			"%s - pkt dropped", __FUNCTION__);
+	} else if (garmin_data_p->state != STATE_DISCONNECTED &&
+	           garmin_data_p->state != STATE_RESET ) {
+
+		/* remember any appl.layer packets, so we know
+		   if a reset is required or not when closing
+		   the device */
+		if (0 == memcmp(data, GARMIN_APP_LAYER_REPLY,
+		                sizeof(GARMIN_APP_LAYER_REPLY)))
+			garmin_data_p->flags |= FLAGS_APP_RESP_SEEN;
+
+		/* if throttling is active or postprecessing is required
+		   put the received data in th input queue, otherwise
+		   send it directly to the tty port */
+		if (garmin_data_p->flags & FLAGS_QUEUING) {
+			pkt_add(garmin_data_p, data,
+			        urb->actual_length);
+		} else if (garmin_data_p->mode == MODE_GARMIN_SERIAL) {
+			if (get_int(data) == GARMIN_LAYERID_APPL) {
+				pkt_add(garmin_data_p, data,
+			        	urb->actual_length);
+			}
+		} else {
+			send_to_tty(port, data, urb->actual_length);
+		}
+	}
+
+	port->interrupt_in_urb->dev = port->serial->dev;
+	status = usb_submit_urb (urb, GFP_ATOMIC);
+	if (status)
+		dev_err(&urb->dev->dev,
+			"%s - Error %d submitting interrupt urb\n",
+			__FUNCTION__, status);
+}
+
+
+/*
+ * Sends the next queued packt to the tty port (garmin native mode only)
+ * and then sets a timer to call itself again until all queued data
+ * is sent.
+ */
+static int garmin_flush_queue(struct garmin_data * garmin_data_p)
+{
+	struct garmin_packet *pkt;
+
+	if ((garmin_data_p->flags & FLAGS_THROTTLED) == 0) {
+		pkt = pkt_pop(garmin_data_p);
+		if (pkt != 0) {
+
+			send_to_tty(garmin_data_p->port, pkt->data, pkt->size);
+			kfree(pkt);
+			mod_timer(&garmin_data_p->timer, (1)+jiffies);
+
+		} else {
+			garmin_data_p->flags &= ~FLAGS_QUEUING;
+		}
+	}
+	return 0;
+}
+
+
+static void garmin_throttle (struct usb_serial_port *port)
+{
+	struct garmin_data * garmin_data_p
+		= (struct garmin_data *) usb_get_serial_port_data(port);
+
+	dbg_drv(garmin_data_p, "%s - port %d", __FUNCTION__, port->number);
+	/* set flag, data received will be put into a queue
+	   for later processing */
+	garmin_data_p->flags |= FLAGS_QUEUING|FLAGS_THROTTLED;
+}
+
+
+static void garmin_unthrottle (struct usb_serial_port *port)
+{
+	struct garmin_data * garmin_data_p
+		= (struct garmin_data *) usb_get_serial_port_data(port);
+
+	dbg_drv(garmin_data_p, "%s - port %d", __FUNCTION__, port->number);
+	garmin_data_p->flags &= ~FLAGS_THROTTLED;
+
+	/* in native mode send queued data to tty, in
+	   serial mode nothing needs to be done here */
+	if (garmin_data_p->mode == MODE_NATIVE)
+		garmin_flush_queue(garmin_data_p);
+}
+
+
+static int gpsmap_probe (struct usb_serial *serial,
+                         const struct usb_device_id *id)
+{
+	return 0;
+}
+
+
+static int garmin_probe (struct usb_serial *serial,
+                         const struct usb_device_id *id)
+{
+	int retval = 0;
+	int (*startup) (struct usb_serial *, const struct usb_device_id *);
+
+	if (serial->dev->actconfig->desc.bConfigurationValue != 1) {
+		err("active config #%d != 1 ??",
+			serial->dev->actconfig->desc.bConfigurationValue);
+		return -ENODEV;
+	}
+
+	if (id->driver_info) {
+		startup = (void *)id->driver_info;
+		retval = startup(serial, id);
+	}
+
+	return retval;
+}
+
+
+static int garmin_attach (struct usb_serial *serial)
+{
+	int status = 0;
+	struct usb_serial_port *port = serial->port[0];
+	struct garmin_data * garmin_data_p = 0;
+
+	garmin_data_p = kmalloc (sizeof(struct garmin_data), GFP_KERNEL);
+	if (garmin_data_p == NULL) {
+		dev_err(&port->dev, "%s - Out of memory\n", __FUNCTION__);
+		return -ENOMEM;
+	}
+	memset (garmin_data_p, 0, sizeof(struct garmin_data));
+	init_timer(&garmin_data_p->timer);
+	spin_lock_init(&garmin_data_p->lock);
+	INIT_LIST_HEAD(&garmin_data_p->pktlist);
+	//garmin_data_p->timer.expires = jiffies + session_timeout;
+	garmin_data_p->timer.data = (unsigned long)garmin_data_p;
+	garmin_data_p->timer.function = timeout_handler;
+	garmin_data_p->port = port;
+	garmin_data_p->state = 0;
+	garmin_data_p->count = 0;
+	usb_set_serial_port_data(port, garmin_data_p);
+
+	status = garmin_init_session(port);
+
+	return status;
+}
+
+
+static void garmin_shutdown (struct usb_serial *serial)
+{
+	int status = 0;
+	struct usb_serial_port *port = serial->port[0];
+	struct garmin_data * garmin_data_p
+		= (struct garmin_data *) usb_get_serial_port_data(port);
+
+	status = usb_unlink_urb (port->interrupt_in_urb);
+	if (status)
+		dbg_drv(garmin_data_p,
+			"%s - port %d - "
+			"error %d during unlink interrupt_in_urb",
+			__FUNCTION__, port->number, status);
+
+	dbg_drv(garmin_data_p, "%s", __FUNCTION__);
+
+	del_timer_sync(&garmin_data_p->timer);
+	kfree (garmin_data_p);
+	usb_set_serial_port_data(port, NULL);
+}
+
+
+/*
+ * does nothing useful at the moment
+ */
+static int garmin_ioctl (struct usb_serial_port *port,
+                         struct file * file, unsigned int cmd,
+                         unsigned long arg)
+{
+	unsigned int status = 0;
+	void * user_p = (void *) arg;
+
+	switch(cmd)
+	{
+	case TIOCSERGETLSR:
+		status = TIOCSER_TEMT;
+		if (copy_to_user(user_p, &status, sizeof(int)))
+			return -EFAULT;
+		return 0;
+
+	default:
+		return -ENOIOCTLCMD;
+	}
+}
+
+
+/* This function is all nice and good,
+   but we don't change anything based on it :) */
+static void garmin_set_termios (struct usb_serial_port *port,
+                                struct termios *old_termios)
+{
+	struct garmin_data * garmin_data_p
+		= (struct garmin_data *) usb_get_serial_port_data(port);
+	unsigned int cflag;
+
+	dbg_drv(garmin_data_p, "%s - port %d", __FUNCTION__, port->number);
+
+	if ((!port->tty) || (!port->tty->termios)) {
+		dbg_drv(garmin_data_p, "%s - no tty structures", __FUNCTION__);
+		return;
+	}
+
+	cflag = port->tty->termios->c_cflag;
+	/* check that they really want us to change something */
+	if (old_termios) {
+		if ((cflag == old_termios->c_cflag) &&
+		    (RELEVANT_IFLAG(port->tty->termios->c_iflag)
+				== RELEVANT_IFLAG(old_termios->c_iflag))) {
+			dbg_drv(garmin_data_p,
+				"%s - nothing to change...", __FUNCTION__);
+			return;
+		}
+	}
+
+	/* get the byte size */
+	switch (cflag & CSIZE) {
+		case CS5:
+			dbg_drv(garmin_data_p,
+				"%s - data bits = 5", __FUNCTION__);
+			break;
+		case CS6:
+			dbg_drv(garmin_data_p,
+				"%s - data bits = 6", __FUNCTION__);
+			break;
+		case CS7:
+			dbg_drv(garmin_data_p,
+				"%s - data bits = 7", __FUNCTION__);
+			break;
+		default:
+		case CS8:
+			dbg_drv(garmin_data_p,
+				"%s - data bits = 8", __FUNCTION__);
+			break;
+	}
+
+	/* determine the parity */
+	if (cflag & PARENB)
+		if (cflag & PARODD)
+			dbg_drv(garmin_data_p,
+				"%s - parity = odd", __FUNCTION__);
+		else
+			dbg_drv(garmin_data_p,
+				"%s - parity = even", __FUNCTION__);
+	else
+		dbg_drv(garmin_data_p,
+			"%s - parity = none", __FUNCTION__);
+
+	/* figure out the stop bits requested */
+	if (cflag & CSTOPB)
+		dbg_drv(garmin_data_p, "%s - stop bits = 2", __FUNCTION__);
+	else
+		dbg_drv(garmin_data_p, "%s - stop bits = 1", __FUNCTION__);
+
+
+	/* figure out the flow control settings */
+	if (cflag & CRTSCTS)
+		dbg_drv(garmin_data_p, "%s - RTS/CTS is enabled", __FUNCTION__);
+	else
+		dbg_drv(garmin_data_p, "%s - RTS/CTS is disabled",__FUNCTION__);
+
+	/* determine software flow control */
+	if (I_IXOFF(port->tty))
+		dbg_drv(garmin_data_p,
+			"%s - XON/XOFF is enabled, XON = %2x, XOFF = %2x",
+			__FUNCTION__, START_CHAR(port->tty),
+			STOP_CHAR(port->tty));
+	else
+		dbg_drv(garmin_data_p,
+			"%s - XON/XOFF is disabled", __FUNCTION__);
+
+	/* get the baud rate wanted */
+	dbg_drv(garmin_data_p,
+		"%s - baud rate = %d", __FUNCTION__,
+		tty_get_baud_rate(port->tty));
+
+	return;
+}
+
+
+
+static int __init garmin_init (void)
+{
+	int i, retval;
+
+	/* Only if parameters were passed to us */
+	if ((vendor>0) && (product>0)) {
+		struct usb_device_id usb_dev_temp[]=
+			{{USB_DEVICE(vendor, product),
+			.driver_info = (kernel_ulong_t)&gpsmap_probe }};
+
+		/* Find the last entry in id_table */
+		for (i=0; ; i++) {
+			if (id_table[i].idVendor==0) {
+				id_table[i] = usb_dev_temp[0];
+				break;
+			}
+		}
+		/* Find the last entry in id_table_combined */
+		for (i=0; ; i++) {
+			if (id_table_combined[i].idVendor==0) {
+				id_table_combined[i] = usb_dev_temp[0];
+				break;
+			}
+		}
+		info("Untested USB device specified at time of module insertion");
+		info("Warning: This is not guaranteed to work");
+		info("Using a newer kernel is preferred to this method");
+		info("Adding garmin-gps support for unknown device: 0x%x/0x%x",
+			vendor, product);
+	}
+	retval = usb_serial_register(&garmin_device);
+	if (retval)
+		goto failed_garmin_register;
+	retval = usb_register(&garmin_driver);
+	if (retval)
+		goto failed_usb_register;
+	info(DRIVER_DESC " " DRIVER_VERSION);
+
+	return 0;
+failed_usb_register:
+	usb_serial_deregister(&garmin_device);
+failed_garmin_register:
+	return retval;
+}
+
+
+static void __exit garmin_exit (void)
+{
+	usb_deregister (&garmin_driver);
+	usb_serial_deregister (&garmin_device);
+}
+
+
+
+
+module_init(garmin_init);
+module_exit(garmin_exit);
+
+MODULE_AUTHOR( DRIVER_AUTHOR );
+MODULE_DESCRIPTION( DRIVER_DESC );
+MODULE_LICENSE("GPL");
+
+MODULE_PARM(debug, "i");
+MODULE_PARM_DESC(debug, "Debug enabled or not");
+MODULE_PARM(initial_mode, "i");
+MODULE_PARM_DESC(initial_mode, "Initial mode");
+
+MODULE_PARM(vendor, "i");
+MODULE_PARM_DESC(vendor, "User specified vendor ID");
+MODULE_PARM(product, "i");
+MODULE_PARM_DESC(product, "User specified product ID");
+
+
diff -Naur linux-2.6.9/drivers/usb/serial/Kconfig linux-2.6.9-gps/drivers/usb/serial/Kconfig
--- linux-2.6.9/drivers/usb/serial/Kconfig	2004-10-18 23:54:40.000000000 +0200
+++ linux-2.6.9-gps/drivers/usb/serial/Kconfig	2004-10-19 20:24:51.999313133 +0200
@@ -127,6 +127,19 @@
 	  To compile this driver as a module, choose M here: the
 	  module will be called visor.
 
+config USB_SERIAL_GARMIN
+	tristate "Garmin GPS driver"
+	depends on USB_SERIAL
+	help
+	  Say Y here if you want to connect to your Garmin GPS.
+	  Should work with most Garmin GPS devices which have a native USB port.
+
+	  See <http://sourceforge.net/projects/garmin-gps> for the latest
+	  version of the driver.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called garmin_gps.
+
 config USB_SERIAL_IPAQ
 	tristate "USB PocketPC PDA Driver"
 	depends on USB_SERIAL
diff -Naur linux-2.6.9/drivers/usb/serial/Makefile linux-2.6.9-gps/drivers/usb/serial/Makefile
--- linux-2.6.9/drivers/usb/serial/Makefile	2004-10-18 23:53:22.000000000 +0200
+++ linux-2.6.9-gps/drivers/usb/serial/Makefile	2004-10-19 20:24:52.000312993 +0200
@@ -29,6 +29,7 @@
 obj-$(CONFIG_USB_SERIAL_PL2303)			+= pl2303.o
 obj-$(CONFIG_USB_SERIAL_SAFE)			+= safe_serial.o
 obj-$(CONFIG_USB_SERIAL_VISOR)			+= visor.o
+obj-$(CONFIG_USB_SERIAL_GARMIN)			+= garmin_gps.o
 obj-$(CONFIG_USB_SERIAL_WHITEHEAT)		+= whiteheat.o
 obj-$(CONFIG_USB_SERIAL_XIRCOM)			+= keyspan_pda.o
 

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