gl620a.c

Go to the documentation of this file.

/*
 * GeneSys GL620USB-A based links
 * Copyright (C) 2001 by Jiun-Jie Huang <[email protected]>
 * Copyright (C) 2001 by Stanislav Brabec <[email protected]>
 *
 * 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/module.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 <linux/usb/usbnet.h>
#include <linux/gfp.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 protected]>
 * and merged into "usbnet" by Stanislav Brabec <[email protected]>.
 */

// 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 {
    __le32      packet_length;
    char        packet_data [1];
};

struct gl_header {
    __le32          packet_count;
    struct gl_packet    packets;
};

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;
    u32         count;

    header = (struct gl_header *) skb->data;

    // get the packet count of the received skb
    count = le32_to_cpu(header->packet_count);
    if (count > GL_MAX_TRANSMIT_PACKETS) {
        netdev_dbg(dev->net,
               "genelink: invalid received packet count %u\n",
               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 (count > 1) {
        // get the packet length
        size = le32_to_cpu(packet->packet_length);

        // this may be a broken packet
        if (size > GL_MAX_PACKET_LEN) {
            netdev_dbg(dev->net, "genelink: invalid rx length %d\n",
                   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];
        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) {
        netdev_dbg(dev->net, "genelink: invalid rx length %d\n",
               skb->len);
        return 0;
    }
    return 1;
}

static struct sk_buff *
genelink_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
{
    int     padlen;
    int length = skb->len;
    int headroom = skb_headroom(skb);
    int tailroom = skb_tailroom(skb);
    __le32  *packet_count;
    __le32  *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_set_tail_pointer(skb, 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 = (__le32 *) skb_push(skb, (4 + 4*1));
    packet_len = packet_count + 1;

    *packet_count = cpu_to_le32(1);
    *packet_len = cpu_to_le32(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;
    dev->in = usb_rcvbulkpipe(dev->udev, dev->driver_info->in);
    dev->out = usb_sndbulkpipe(dev->udev, dev->driver_info->out);
    return 0;
}

static const struct driver_info genelink_info = {
    .description =  "Genesys GeneLink",
    .flags =    FLAG_POINTTOPOINT | 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 = {
    .name =     "gl620a",
    .id_table = products,
    .probe =    usbnet_probe,
    .disconnect =   usbnet_disconnect,
    .suspend =  usbnet_suspend,
    .resume =   usbnet_resume,
    .disable_hub_initiated_lpm = 1,
};

module_usb_driver(gl620a_driver);

MODULE_AUTHOR("Jiun-Jie Huang");
MODULE_DESCRIPTION("GL620-USB-A Host-to-Host Link cables");
MODULE_LICENSE("GPL");