Subject: USB: usbnet (5/9) module for genesys gl620a cables

From: David Brownell <[email-masked]>
Date: Sat, 13 Aug 2005 14:10:54 -0700

Another host-to-host cable using custom framing to interop with Win32.
This moves the GeneSys GL620USB-A support into its own driver file.

Signed-off-by: David Brownell <[email-masked]>

---
 drivers/usb/net/Kconfig  |   20 +-
 drivers/usb/net/Makefile |    1 
 drivers/usb/net/gl620a.c |  408 +++++++++++++++++++++++++++++++++++++++++++++++
 drivers/usb/net/usbnet.c |  348 ----------------------------------------
 4 files changed, 419 insertions(+), 358 deletions(-)

--- gregkh-2.6.orig/drivers/usb/net/Makefile	2005-08-30 12:23:40.000000000 -0700
+++ gregkh-2.6/drivers/usb/net/Makefile	2005-08-30 12:23:46.000000000 -0700
@@ -7,6 +7,7 @@ obj-$(CONFIG_USB_KAWETH)	+= kaweth.o
 obj-$(CONFIG_USB_PEGASUS)	+= pegasus.o
 obj-$(CONFIG_USB_RTL8150)	+= rtl8150.o
 obj-$(CONFIG_USB_NET_AX8817X)	+= asix.o
+obj-$(CONFIG_USB_NET_GL620A)	+= gl620a.o
 obj-$(CONFIG_USB_NET_NET1080)	+= net1080.o
 obj-$(CONFIG_USB_NET_SIMPLE)	+= simple.o
 obj-$(CONFIG_USB_USBNET)	+= usbnet.o
--- gregkh-2.6.orig/drivers/usb/net/Kconfig	2005-08-30 12:23:40.000000000 -0700
+++ gregkh-2.6/drivers/usb/net/Kconfig	2005-08-30 12:23:46.000000000 -0700
@@ -128,16 +128,6 @@ config USB_USBNET
 comment "USB Host-to-Host Cables"
 	depends on USB_USBNET
 
-config USB_GENESYS
-	boolean "GeneSys GL620USB-A based cables"
-	default y
-	depends on USB_USBNET
-	help
-	  Choose this option if you're using a host-to-host cable,
-	  or PC2PC motherboard, with this chip.
-
-	  Note that the half-duplex "GL620USB" is not supported.
-
 config USB_PL2301
 	boolean "Prolific PL-2301/2302 based cables"
 	default y
@@ -224,6 +214,16 @@ config USB_NET_AX8817X
 	  what other networking devices you have in use.  

+config USB_NET_GL620A
+	tristate "GeneSys GL620USB-A based cables"
+	default y
+	depends on USB_USBNET
+	help
+	  Choose this option if you're using a host-to-host cable,
+	  or PC2PC motherboard, with this chip.
+
+	  Note that the half-duplex "GL620USB" is not supported.
+
 config USB_NET_NET1080
 	tristate "NetChip 1080 based cables (Laplink, ...)"
 	default y
--- gregkh-2.6.orig/drivers/usb/net/usbnet.c	2005-08-30 12:23:40.000000000 -0700
+++ gregkh-2.6/drivers/usb/net/usbnet.c	2005-08-30 12:24:38.000000000 -0700
@@ -152,9 +152,6 @@
 // us (it polls at HZ/4 usually) before we report too many false errors.
 #define THROTTLE_JIFFIES	(HZ/8)
 
-// for vendor-specific control operations
-#define	CONTROL_TIMEOUT_MS	USB_CTRL_GET_TIMEOUT
-
 // between wakeups
 #define UNLINK_TIMEOUT_MS	3
 
@@ -686,341 +683,6 @@ static const struct driver_info	cdc_info

 
-#ifdef CONFIG_USB_GENESYS
-#define	HAVE_HARDWARE
-
-/*-------------------------------------------------------------------------
- *
- * GeneSys GL620USB-A (www.genesyslogic.com.tw)
- *
- * ... should partially interop with the Win32 driver for this hardware
- * The GeneSys docs imply there's some NDIS issue motivating this framing.
- *
- * Some info from GeneSys:
- *  - GL620USB-A is full duplex; GL620USB is only half duplex for bulk.
- *    (Some cables, like the BAFO-100c, use the half duplex version.)
- *  - For the full duplex model, the low bit of the version code says
- *    which side is which ("left/right").
- *  - For the half duplex type, a control/interrupt handshake settles
- *    the transfer direction.  (That's disabled here, partially coded.)
- *    A control URB would block until other side writes an interrupt.
- *
- * Original code from Jiun-Jie Huang <[email-masked]>
- * and merged into "usbnet" by Stanislav Brabec <[email-masked]>.
- *
- *-------------------------------------------------------------------------*/
-
-// control msg write command
-#define GENELINK_CONNECT_WRITE			0xF0
-// interrupt pipe index
-#define GENELINK_INTERRUPT_PIPE			0x03
-// interrupt read buffer size
-#define INTERRUPT_BUFSIZE			0x08
-// interrupt pipe interval value
-#define GENELINK_INTERRUPT_INTERVAL		0x10
-// max transmit packet number per transmit
-#define GL_MAX_TRANSMIT_PACKETS			32
-// max packet length
-#define GL_MAX_PACKET_LEN			1514
-// max receive buffer size 
-#define GL_RCV_BUF_SIZE		\
-	(((GL_MAX_PACKET_LEN + 4) * GL_MAX_TRANSMIT_PACKETS) + 4)
-
-struct gl_packet {
-	u32		packet_length;
-	char		packet_data [1];
-};
-
-struct gl_header {
-	u32			packet_count;
-	struct gl_packet	packets;
-};
-
-#ifdef	GENELINK_ACK
-
-// FIXME:  this code is incomplete, not debugged; it doesn't
-// handle interrupts correctly.  interrupts should be generic
-// code like all other device I/O, anyway.
-
-struct gl_priv { 
-	struct urb	*irq_urb;
-	char		irq_buf [INTERRUPT_BUFSIZE];
-};
-
-static inline int gl_control_write (struct usbnet *dev, u8 request, u16 value)
-{
-	int retval;
-
-	retval = usb_control_msg (dev->udev,
-		      usb_sndctrlpipe (dev->udev, 0),
-		      request,
-		      USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
-		      value, 
-		      0,			// index
-		      0,			// data buffer
-		      0,			// size
-		      CONTROL_TIMEOUT_MS);
-	return retval;
-}
-
-static void gl_interrupt_complete (struct urb *urb, struct pt_regs *regs)
-{
-	int status = urb->status;
-	
-	switch (status) {
-	case 0:
-		/* success */
-		break;
-	case -ECONNRESET:
-	case -ENOENT:
-	case -ESHUTDOWN:
-		/* this urb is terminated, clean up */
-		dbg("%s - urb shutting down with status: %d",
-				__FUNCTION__, status);
-		return;
-	default:
-		dbg("%s - nonzero urb status received: %d",
-				__FUNCTION__, urb->status);
-	}
-
-	status = usb_submit_urb (urb, GFP_ATOMIC);
-	if (status)
-		err ("%s - usb_submit_urb failed with result %d",
-		     __FUNCTION__, status);
-}
-
-static int gl_interrupt_read (struct usbnet *dev)
-{
-	struct gl_priv	*priv = dev->priv_data;
-	int		retval;
-
-	// issue usb interrupt read
-	if (priv && priv->irq_urb) {
-		// submit urb
-		if ((retval = usb_submit_urb (priv->irq_urb, GFP_KERNEL)) != 0)
-			dbg ("gl_interrupt_read: submit fail - %X...", retval);
-		else
-			dbg ("gl_interrupt_read: submit success...");
-	}
-
-	return 0;
-}
-
-// check whether another side is connected
-static int genelink_check_connect (struct usbnet *dev)
-{
-	int			retval;
-
-	dbg ("genelink_check_connect...");
-
-	// detect whether another side is connected
-	if ((retval = gl_control_write (dev, GENELINK_CONNECT_WRITE, 0)) != 0) {
-		dbg ("%s: genelink_check_connect write fail - %X",
-			dev->net->name, retval);
-		return retval;
-	}
-
-	// usb interrupt read to ack another side 
-	if ((retval = gl_interrupt_read (dev)) != 0) {
-		dbg ("%s: genelink_check_connect read fail - %X",
-			dev->net->name, retval);
-		return retval;
-	}
-
-	dbg ("%s: genelink_check_connect read success", dev->net->name);
-	return 0;
-}
-
-// allocate and initialize the private data for genelink
-static int genelink_init (struct usbnet *dev)
-{
-	struct gl_priv *priv;
-
-	// allocate the private data structure
-	if ((priv = kmalloc (sizeof *priv, GFP_KERNEL)) == 0) {
-		dbg ("%s: cannot allocate private data per device",
-			dev->net->name);
-		return -ENOMEM;
-	}
-
-	// allocate irq urb
-	if ((priv->irq_urb = usb_alloc_urb (0, GFP_KERNEL)) == 0) {
-		dbg ("%s: cannot allocate private irq urb per device",
-			dev->net->name);
-		kfree (priv);
-		return -ENOMEM;
-	}
-
-	// fill irq urb
-	usb_fill_int_urb (priv->irq_urb, dev->udev,
-		usb_rcvintpipe (dev->udev, GENELINK_INTERRUPT_PIPE),
-		priv->irq_buf, INTERRUPT_BUFSIZE,
-		gl_interrupt_complete, 0,
-		GENELINK_INTERRUPT_INTERVAL);
-
-	// set private data pointer
-	dev->priv_data = priv;
-
-	return 0;
-}
-
-// release the private data
-static int genelink_free (struct usbnet *dev)
-{
-	struct gl_priv	*priv = dev->priv_data;
-
-	if (!priv) 
-		return 0;
-
-// FIXME:  can't cancel here; it's synchronous, and
-// should have happened earlier in any case (interrupt
-// handling needs to be generic)
-
-	// cancel irq urb first
-	usb_kill_urb (priv->irq_urb);
-
-	// free irq urb
-	usb_free_urb (priv->irq_urb);
-
-	// free the private data structure
-	kfree (priv);
-
-	return 0;
-}
-
-#endif
-
-static int genelink_rx_fixup (struct usbnet *dev, struct sk_buff *skb)
-{
-	struct gl_header	*header;
-	struct gl_packet	*packet;
-	struct sk_buff		*gl_skb;
-	u32			size;
-
-	header = (struct gl_header *) skb->data;
-
-	// get the packet count of the received skb
-	le32_to_cpus (&header->packet_count);
-	if ((header->packet_count > GL_MAX_TRANSMIT_PACKETS)
-			|| (header->packet_count < 0)) {
-		dbg ("genelink: invalid received packet count %d",
-			header->packet_count);
-		return 0;
-	}
-
-	// set the current packet pointer to the first packet
-	packet = &header->packets;
-
-	// decrement the length for the packet count size 4 bytes
-	skb_pull (skb, 4);
-
-	while (header->packet_count > 1) {
-		// get the packet length
-		size = packet->packet_length;
-
-		// this may be a broken packet
-		if (size > GL_MAX_PACKET_LEN) {
-			dbg ("genelink: invalid rx length %d", size);
-			return 0;
-		}
-
-		// allocate the skb for the individual packet
-		gl_skb = alloc_skb (size, GFP_ATOMIC);
-		if (gl_skb) {
-
-			// copy the packet data to the new skb
-			memcpy(skb_put(gl_skb, size), packet->packet_data, size);
-			usbnet_skb_return (dev, gl_skb);
-		}
-
-		// advance to the next packet
-		packet = (struct gl_packet *)
-			&packet->packet_data [size];
-		header->packet_count--;
-
-		// shift the data pointer to the next gl_packet
-		skb_pull (skb, size + 4);
-	}
-
-	// skip the packet length field 4 bytes
-	skb_pull (skb, 4);
-
-	if (skb->len > GL_MAX_PACKET_LEN) {
-		dbg ("genelink: invalid rx length %d", skb->len);
-		return 0;
-	}
-	return 1;
-}
-
-static struct sk_buff *
-genelink_tx_fixup (struct usbnet *dev, struct sk_buff *skb, unsigned flags)
-{
-	int 	padlen;
-	int	length = skb->len;
-	int	headroom = skb_headroom (skb);
-	int	tailroom = skb_tailroom (skb);
-	u32	*packet_count;
-	u32	*packet_len;
-
-	// FIXME:  magic numbers, bleech
-	padlen = ((skb->len + (4 + 4*1)) % 64) ? 0 : 1;
-
-	if ((!skb_cloned (skb))
-			&& ((headroom + tailroom) >= (padlen + (4 + 4*1)))) {
-		if ((headroom < (4 + 4*1)) || (tailroom < padlen)) {
-			skb->data = memmove (skb->head + (4 + 4*1),
-					     skb->data, skb->len);
-			skb->tail = skb->data + skb->len;
-		}
-	} else {
-		struct sk_buff	*skb2;
-		skb2 = skb_copy_expand (skb, (4 + 4*1) , padlen, flags);
-		dev_kfree_skb_any (skb);
-		skb = skb2;
-		if (!skb)
-			return NULL;
-	}
-
-	// attach the packet count to the header
-	packet_count = (u32 *) skb_push (skb, (4 + 4*1));
-	packet_len = packet_count + 1;
-
-	// FIXME little endian?
-	*packet_count = 1;
-	*packet_len = length;
-
-	// add padding byte
-	if ((skb->len % dev->maxpacket) == 0)
-		skb_put (skb, 1);
-
-	return skb;
-}
-
-static int genelink_bind (struct usbnet *dev, struct usb_interface *intf)
-{
-	dev->hard_mtu = GL_RCV_BUF_SIZE;
-	dev->net->hard_header_len += 4;
-	return 0;
-}
-
-static const struct driver_info	genelink_info = {
-	.description =	"Genesys GeneLink",
-	.flags =	FLAG_FRAMING_GL | FLAG_NO_SETINT,
-	.bind =		genelink_bind,
-	.rx_fixup =	genelink_rx_fixup,
-	.tx_fixup =	genelink_tx_fixup,
-
-	.in = 1, .out = 2,
-
-#ifdef	GENELINK_ACK
-	.check_connect =genelink_check_connect,
-#endif
-};
-
-#endif /* CONFIG_USB_GENESYS */
-
-
-
 #ifdef CONFIG_USB_PL2301
 #define	HAVE_HARDWARE
 
@@ -2305,16 +1967,6 @@ EXPORT_SYMBOL_GPL(usbnet_resume);
 
 static const struct usb_device_id	products [] = {
 
-#ifdef	CONFIG_USB_GENESYS
-{
-	USB_DEVICE (0x05e3, 0x0502),	// GL620USB-A
-	.driver_info =	(unsigned long) &genelink_info,
-},
-	/* NOT: USB_DEVICE (0x05e3, 0x0501),	// GL620USB
-	 * that's half duplex, not currently supported
-	 */
-#endif
-
 #ifdef CONFIG_USB_PL2301
 {
 	USB_DEVICE (0x067b, 0x0000),	// PL-2301
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gregkh-2.6/drivers/usb/net/gl620a.c	2005-08-30 12:23:46.000000000 -0700
@@ -0,0 +1,408 @@
+/*
+ * GeneSys GL620USB-A based links
+ * Copyright (C) 2001 by Jiun-Jie Huang <[email-masked]>
+ * Copyright (C) 2001 by Stanislav Brabec <[email-masked]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+// #define	DEBUG			// error path messages, extra info
+// #define	VERBOSE			// more; success messages
+
+#include <linux/config.h>
+#ifdef	CONFIG_USB_DEBUG
+#   define DEBUG
+#endif
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/ethtool.h>
+#include <linux/workqueue.h>
+#include <linux/mii.h>
+#include <linux/usb.h>
+
+#include "usbnet.h"
+
+
+/*
+ * GeneSys GL620USB-A (www.genesyslogic.com.tw)
+ *
+ * ... should partially interop with the Win32 driver for this hardware.
+ * The GeneSys docs imply there's some NDIS issue motivating this framing.
+ *
+ * Some info from GeneSys:
+ *  - GL620USB-A is full duplex; GL620USB is only half duplex for bulk.
+ *    (Some cables, like the BAFO-100c, use the half duplex version.)
+ *  - For the full duplex model, the low bit of the version code says
+ *    which side is which ("left/right").
+ *  - For the half duplex type, a control/interrupt handshake settles
+ *    the transfer direction.  (That's disabled here, partially coded.)
+ *    A control URB would block until other side writes an interrupt.
+ *
+ * Original code from Jiun-Jie Huang <[email-masked]>
+ * and merged into "usbnet" by Stanislav Brabec <[email-masked]>.
+ *
+ * NOTE:  This driver is missing some byteswapping; big-endian hosts
+ * will have problems talking to little-endian ones.
+ */
+
+// control msg write command
+#define GENELINK_CONNECT_WRITE			0xF0
+// interrupt pipe index
+#define GENELINK_INTERRUPT_PIPE			0x03
+// interrupt read buffer size
+#define INTERRUPT_BUFSIZE			0x08
+// interrupt pipe interval value
+#define GENELINK_INTERRUPT_INTERVAL		0x10
+// max transmit packet number per transmit
+#define GL_MAX_TRANSMIT_PACKETS			32
+// max packet length
+#define GL_MAX_PACKET_LEN			1514
+// max receive buffer size
+#define GL_RCV_BUF_SIZE		\
+	(((GL_MAX_PACKET_LEN + 4) * GL_MAX_TRANSMIT_PACKETS) + 4)
+
+struct gl_packet {
+	u32		packet_length;
+	char		packet_data [1];
+};
+
+struct gl_header {
+	u32			packet_count;
+	struct gl_packet	packets;
+};
+
+#ifdef	GENELINK_ACK
+
+// FIXME:  this code is incomplete, not debugged; it doesn't
+// handle interrupts correctly.  interrupts should be generic
+// code like all other device I/O, anyway.
+
+struct gl_priv {
+	struct urb	*irq_urb;
+	char		irq_buf [INTERRUPT_BUFSIZE];
+};
+
+static inline int gl_control_write(struct usbnet *dev, u8 request, u16 value)
+{
+	int retval;
+
+	retval = usb_control_msg(dev->udev,
+		      usb_sndctrlpipe(dev->udev, 0),
+		      request,
+		      USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+		      value,
+		      0,			// index
+		      0,			// data buffer
+		      0,			// size
+		      CONTROL_TIMEOUT_MS);
+	return retval;
+}
+
+static void gl_interrupt_complete(struct urb *urb, struct pt_regs *regs)
+{
+	int status = urb->status;
+
+	switch (status) {
+	case 0:
+		/* success */
+		break;
+	case -ECONNRESET:
+	case -ENOENT:
+	case -ESHUTDOWN:
+		/* this urb is terminated, clean up */
+		dbg("%s - urb shutting down with status: %d",
+				__FUNCTION__, status);
+		return;
+	default:
+		dbg("%s - nonzero urb status received: %d",
+				__FUNCTION__, urb->status);
+	}
+
+	status = usb_submit_urb(urb, GFP_ATOMIC);
+	if (status)
+		err("%s - usb_submit_urb failed with result %d",
+		     __FUNCTION__, status);
+}
+
+static int gl_interrupt_read(struct usbnet *dev)
+{
+	struct gl_priv	*priv = dev->priv_data;
+	int		retval;
+
+	// issue usb interrupt read
+	if (priv && priv->irq_urb) {
+		// submit urb
+		if ((retval = usb_submit_urb(priv->irq_urb, GFP_KERNEL)) != 0)
+			dbg("gl_interrupt_read: submit fail - %X...", retval);
+		else
+			dbg("gl_interrupt_read: submit success...");
+	}
+
+	return 0;
+}
+
+// check whether another side is connected
+static int genelink_check_connect(struct usbnet *dev)
+{
+	int			retval;
+
+	dbg("genelink_check_connect...");
+
+	// detect whether another side is connected
+	if ((retval = gl_control_write(dev, GENELINK_CONNECT_WRITE, 0)) != 0) {
+		dbg("%s: genelink_check_connect write fail - %X",
+			dev->net->name, retval);
+		return retval;
+	}
+
+	// usb interrupt read to ack another side
+	if ((retval = gl_interrupt_read(dev)) != 0) {
+		dbg("%s: genelink_check_connect read fail - %X",
+			dev->net->name, retval);
+		return retval;
+	}
+
+	dbg("%s: genelink_check_connect read success", dev->net->name);
+	return 0;
+}
+
+// allocate and initialize the private data for genelink
+static int genelink_init(struct usbnet *dev)
+{
+	struct gl_priv *priv;
+
+	// allocate the private data structure
+	if ((priv = kmalloc(sizeof *priv, GFP_KERNEL)) == 0) {
+		dbg("%s: cannot allocate private data per device",
+			dev->net->name);
+		return -ENOMEM;
+	}
+
+	// allocate irq urb
+	if ((priv->irq_urb = usb_alloc_urb(0, GFP_KERNEL)) == 0) {
+		dbg("%s: cannot allocate private irq urb per device",
+			dev->net->name);
+		kfree(priv);
+		return -ENOMEM;
+	}
+
+	// fill irq urb
+	usb_fill_int_urb(priv->irq_urb, dev->udev,
+		usb_rcvintpipe(dev->udev, GENELINK_INTERRUPT_PIPE),
+		priv->irq_buf, INTERRUPT_BUFSIZE,
+		gl_interrupt_complete, 0,
+		GENELINK_INTERRUPT_INTERVAL);
+
+	// set private data pointer
+	dev->priv_data = priv;
+
+	return 0;
+}
+
+// release the private data
+static int genelink_free(struct usbnet *dev)
+{
+	struct gl_priv	*priv = dev->priv_data;
+
+	if (!priv)
+		return 0;
+
+// FIXME:  can't cancel here; it's synchronous, and
+// should have happened earlier in any case (interrupt
+// handling needs to be generic)
+
+	// cancel irq urb first
+	usb_kill_urb(priv->irq_urb);
+
+	// free irq urb
+	usb_free_urb(priv->irq_urb);
+
+	// free the private data structure
+	kfree(priv);
+
+	return 0;
+}
+
+#endif
+
+static int genelink_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
+{
+	struct gl_header	*header;
+	struct gl_packet	*packet;
+	struct sk_buff		*gl_skb;
+	u32			size;
+
+	header = (struct gl_header *) skb->data;
+
+	// get the packet count of the received skb
+	le32_to_cpus(&header->packet_count);
+	if ((header->packet_count > GL_MAX_TRANSMIT_PACKETS)
+			|| (header->packet_count < 0)) {
+		dbg("genelink: invalid received packet count %d",
+			header->packet_count);
+		return 0;
+	}
+
+	// set the current packet pointer to the first packet
+	packet = &header->packets;
+
+	// decrement the length for the packet count size 4 bytes
+	skb_pull(skb, 4);
+
+	while (header->packet_count > 1) {
+		// get the packet length
+		size = packet->packet_length;
+
+		// this may be a broken packet
+		if (size > GL_MAX_PACKET_LEN) {
+			dbg("genelink: invalid rx length %d", size);
+			return 0;
+		}
+
+		// allocate the skb for the individual packet
+		gl_skb = alloc_skb(size, GFP_ATOMIC);
+		if (gl_skb) {
+
+			// copy the packet data to the new skb
+			memcpy(skb_put(gl_skb, size), packet->packet_data, size);
+			usbnet_skb_return(dev, skb);
+		}
+
+		// advance to the next packet
+		packet = (struct gl_packet *)
+			&packet->packet_data [size];
+		header->packet_count--;
+
+		// shift the data pointer to the next gl_packet
+		skb_pull(skb, size + 4);
+	}
+
+	// skip the packet length field 4 bytes
+	skb_pull(skb, 4);
+
+	if (skb->len > GL_MAX_PACKET_LEN) {
+		dbg("genelink: invalid rx length %d", skb->len);
+		return 0;
+	}
+	return 1;
+}
+
+static struct sk_buff *
+genelink_tx_fixup(struct usbnet *dev, struct sk_buff *skb, unsigned flags)
+{
+	int 	padlen;
+	int	length = skb->len;
+	int	headroom = skb_headroom(skb);
+	int	tailroom = skb_tailroom(skb);
+	u32	*packet_count;
+	u32	*packet_len;
+
+	// FIXME:  magic numbers, bleech
+	padlen = ((skb->len + (4 + 4*1)) % 64) ? 0 : 1;
+
+	if ((!skb_cloned(skb))
+			&& ((headroom + tailroom) >= (padlen + (4 + 4*1)))) {
+		if ((headroom < (4 + 4*1)) || (tailroom < padlen)) {
+			skb->data = memmove(skb->head + (4 + 4*1),
+					     skb->data, skb->len);
+			skb->tail = skb->data + skb->len;
+		}
+	} else {
+		struct sk_buff	*skb2;
+		skb2 = skb_copy_expand(skb, (4 + 4*1) , padlen, flags);
+		dev_kfree_skb_any(skb);
+		skb = skb2;
+		if (!skb)
+			return NULL;
+	}
+
+	// attach the packet count to the header
+	packet_count = (u32 *) skb_push(skb, (4 + 4*1));
+	packet_len = packet_count + 1;
+
+	// FIXME little endian?
+	*packet_count = 1;
+	*packet_len = length;
+
+	// add padding byte
+	if ((skb->len % dev->maxpacket) == 0)
+		skb_put(skb, 1);
+
+	return skb;
+}
+
+static int genelink_bind(struct usbnet *dev, struct usb_interface *intf)
+{
+	dev->hard_mtu = GL_RCV_BUF_SIZE;
+	dev->net->hard_header_len += 4;
+	return 0;
+}
+
+static const struct driver_info	genelink_info = {
+	.description =	"Genesys GeneLink",
+	.flags =	FLAG_FRAMING_GL | FLAG_NO_SETINT,
+	.bind =		genelink_bind,
+	.rx_fixup =	genelink_rx_fixup,
+	.tx_fixup =	genelink_tx_fixup,
+
+	.in = 1, .out = 2,
+
+#ifdef	GENELINK_ACK
+	.check_connect =genelink_check_connect,
+#endif
+};
+
+static const struct usb_device_id	products [] = {
+
+{
+	USB_DEVICE(0x05e3, 0x0502),	// GL620USB-A
+	.driver_info =	(unsigned long) &genelink_info,
+},
+	/* NOT: USB_DEVICE(0x05e3, 0x0501),	// GL620USB
+	 * that's half duplex, not currently supported
+	 */
+	{ },		// END
+};
+MODULE_DEVICE_TABLE(usb, products);
+
+static struct usb_driver gl620a_driver = {
+	.owner =	THIS_MODULE,
+	.name =		"gl620a",
+	.id_table =	products,
+	.probe =	usbnet_probe,
+	.disconnect =	usbnet_disconnect,
+	.suspend =	usbnet_suspend,
+	.resume =	usbnet_resume,
+};
+
+static int __init usbnet_init(void)
+{
+ 	return usb_register(&gl620a_driver);
+}
+module_init(usbnet_init);
+
+static void __exit usbnet_exit(void)
+{
+ 	usb_deregister(&gl620a_driver);
+}
+module_exit(usbnet_exit);
+
+MODULE_AUTHOR("Jiun-Jie Huang");
+MODULE_DESCRIPTION("GL620-USB-A Host-to-Host Link cables");
+MODULE_LICENSE("GPL");
+