net1080.c

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/*
 * Net1080 based USB host-to-host cables
 * Copyright (C) 2000-2005 by David Brownell
 *
 * 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/slab.h>

#include <asm/unaligned.h>


/*
 * Netchip 1080 driver ... http://www.netchip.com
 * (Sept 2004:  End-of-life announcement has been sent.)
 * Used in (some) LapLink cables
 */

#define frame_errors    data[1]

/*
 * NetChip framing of ethernet packets, supporting additional error
 * checks for links that may drop bulk packets from inside messages.
 * Odd USB length == always short read for last usb packet.
 *  - nc_header
 *  - Ethernet header (14 bytes)
 *  - payload
 *  - (optional padding byte, if needed so length becomes odd)
 *  - nc_trailer
 *
 * This framing is to be avoided for non-NetChip devices.
 */

struct nc_header {      // packed:
    __le16  hdr_len;        // sizeof nc_header (LE, all)
    __le16  packet_len;     // payload size (including ethhdr)
    __le16  packet_id;      // detects dropped packets
#define MIN_HEADER  6

    // all else is optional, and must start with:
    // __le16   vendorId;   // from usb-if
    // __le16   productId;
} __packed;

#define PAD_BYTE    ((unsigned char)0xAC)

struct nc_trailer {
    __le16  packet_id;
} __packed;

// packets may use FLAG_FRAMING_NC and optional pad
#define FRAMED_SIZE(mtu) (sizeof (struct nc_header) \
                + sizeof (struct ethhdr) \
                + (mtu) \
                + 1 \
                + sizeof (struct nc_trailer))

#define MIN_FRAMED  FRAMED_SIZE(0)

/* packets _could_ be up to 64KB... */
#define NC_MAX_PACKET   32767


/*
 * Zero means no timeout; else, how long a 64 byte bulk packet may be queued
 * before the hardware drops it.  If that's done, the driver will need to
 * frame network packets to guard against the dropped USB packets.  The win32
 * driver sets this for both sides of the link.
 */
#define NC_READ_TTL_MS  ((u8)255)   // ms

/*
 * We ignore most registers and EEPROM contents.
 */
#define REG_USBCTL  ((u8)0x04)
#define REG_TTL     ((u8)0x10)
#define REG_STATUS  ((u8)0x11)

/*
 * Vendor specific requests to read/write data
 */
#define REQUEST_REGISTER    ((u8)0x10)
#define REQUEST_EEPROM      ((u8)0x11)

static int
nc_vendor_read(struct usbnet *dev, u8 req, u8 regnum, u16 *retval_ptr)
{
    int status = usb_control_msg(dev->udev,
        usb_rcvctrlpipe(dev->udev, 0),
        req,
        USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
        0, regnum,
        retval_ptr, sizeof *retval_ptr,
        USB_CTRL_GET_TIMEOUT);
    if (status > 0)
        status = 0;
    if (!status)
        le16_to_cpus(retval_ptr);
    return status;
}

static inline int
nc_register_read(struct usbnet *dev, u8 regnum, u16 *retval_ptr)
{
    return nc_vendor_read(dev, REQUEST_REGISTER, regnum, retval_ptr);
}

// no retval ... can become async, usable in_interrupt()
static void
nc_vendor_write(struct usbnet *dev, u8 req, u8 regnum, u16 value)
{
    usb_control_msg(dev->udev,
        usb_sndctrlpipe(dev->udev, 0),
        req,
        USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
        value, regnum,
        NULL, 0,            // data is in setup packet
        USB_CTRL_SET_TIMEOUT);
}

static inline void
nc_register_write(struct usbnet *dev, u8 regnum, u16 value)
{
    nc_vendor_write(dev, REQUEST_REGISTER, regnum, value);
}


#if 0
static void nc_dump_registers(struct usbnet *dev)
{
    u8  reg;
    u16 *vp = kmalloc(sizeof (u16));

    if (!vp)
        return;

    netdev_dbg(dev->net, "registers:\n");
    for (reg = 0; reg < 0x20; reg++) {
        int retval;

        // reading some registers is trouble
        if (reg >= 0x08 && reg <= 0xf)
            continue;
        if (reg >= 0x12 && reg <= 0x1e)
            continue;

        retval = nc_register_read(dev, reg, vp);
        if (retval < 0)
            netdev_dbg(dev->net, "reg [0x%x] ==> error %d\n",
                   reg, retval);
        else
            netdev_dbg(dev->net, "reg [0x%x] = 0x%x\n", reg, *vp);
    }
    kfree(vp);
}
#endif


/*-------------------------------------------------------------------------*/

/*
 * Control register
 */

#define USBCTL_WRITABLE_MASK    0x1f0f
// bits 15-13 reserved, r/o
#define USBCTL_ENABLE_LANG  (1 << 12)
#define USBCTL_ENABLE_MFGR  (1 << 11)
#define USBCTL_ENABLE_PROD  (1 << 10)
#define USBCTL_ENABLE_SERIAL    (1 << 9)
#define USBCTL_ENABLE_DEFAULTS  (1 << 8)
// bits 7-4 reserved, r/o
#define USBCTL_FLUSH_OTHER  (1 << 3)
#define USBCTL_FLUSH_THIS   (1 << 2)
#define USBCTL_DISCONN_OTHER    (1 << 1)
#define USBCTL_DISCONN_THIS (1 << 0)

static inline void nc_dump_usbctl(struct usbnet *dev, u16 usbctl)
{
    netif_dbg(dev, link, dev->net,
          "net1080 %s-%s usbctl 0x%x:%s%s%s%s%s; this%s%s; other%s%s; r/o 0x%x\n",
          dev->udev->bus->bus_name, dev->udev->devpath,
          usbctl,
          (usbctl & USBCTL_ENABLE_LANG) ? " lang" : "",
          (usbctl & USBCTL_ENABLE_MFGR) ? " mfgr" : "",
          (usbctl & USBCTL_ENABLE_PROD) ? " prod" : "",
          (usbctl & USBCTL_ENABLE_SERIAL) ? " serial" : "",
          (usbctl & USBCTL_ENABLE_DEFAULTS) ? " defaults" : "",

          (usbctl & USBCTL_FLUSH_THIS) ? " FLUSH" : "",
          (usbctl & USBCTL_DISCONN_THIS) ? " DIS" : "",

          (usbctl & USBCTL_FLUSH_OTHER) ? " FLUSH" : "",
          (usbctl & USBCTL_DISCONN_OTHER) ? " DIS" : "",

          usbctl & ~USBCTL_WRITABLE_MASK);
}

/*-------------------------------------------------------------------------*/

/*
 * Status register
 */

#define STATUS_PORT_A       (1 << 15)

#define STATUS_CONN_OTHER   (1 << 14)
#define STATUS_SUSPEND_OTHER    (1 << 13)
#define STATUS_MAILBOX_OTHER    (1 << 12)
#define STATUS_PACKETS_OTHER(n) (((n) >> 8) & 0x03)

#define STATUS_CONN_THIS    (1 << 6)
#define STATUS_SUSPEND_THIS (1 << 5)
#define STATUS_MAILBOX_THIS (1 << 4)
#define STATUS_PACKETS_THIS(n)  (((n) >> 0) & 0x03)

#define STATUS_UNSPEC_MASK  0x0c8c
#define STATUS_NOISE_MASK   ((u16)~(0x0303|STATUS_UNSPEC_MASK))


static inline void nc_dump_status(struct usbnet *dev, u16 status)
{
    netif_dbg(dev, link, dev->net,
          "net1080 %s-%s status 0x%x: this (%c) PKT=%d%s%s%s; other PKT=%d%s%s%s; unspec 0x%x\n",
          dev->udev->bus->bus_name, dev->udev->devpath,
          status,

          // XXX the packet counts don't seem right
          // (1 at reset, not 0); maybe UNSPEC too

          (status & STATUS_PORT_A) ? 'A' : 'B',
          STATUS_PACKETS_THIS(status),
          (status & STATUS_CONN_THIS) ? " CON" : "",
          (status & STATUS_SUSPEND_THIS) ? " SUS" : "",
          (status & STATUS_MAILBOX_THIS) ? " MBOX" : "",

          STATUS_PACKETS_OTHER(status),
          (status & STATUS_CONN_OTHER) ? " CON" : "",
          (status & STATUS_SUSPEND_OTHER) ? " SUS" : "",
          (status & STATUS_MAILBOX_OTHER) ? " MBOX" : "",

          status & STATUS_UNSPEC_MASK);
}

/*-------------------------------------------------------------------------*/

/*
 * TTL register
 */

#define TTL_THIS(ttl)   (0x00ff & ttl)
#define TTL_OTHER(ttl)  (0x00ff & (ttl >> 8))
#define MK_TTL(this,other)  ((u16)(((other)<<8)|(0x00ff&(this))))

static inline void nc_dump_ttl(struct usbnet *dev, u16 ttl)
{
    netif_dbg(dev, link, dev->net, "net1080 %s-%s ttl 0x%x this = %d, other = %d\n",
          dev->udev->bus->bus_name, dev->udev->devpath,
          ttl, TTL_THIS(ttl), TTL_OTHER(ttl));
}

/*-------------------------------------------------------------------------*/

static int net1080_reset(struct usbnet *dev)
{
    u16     usbctl, status, ttl;
    u16     *vp = kmalloc(sizeof (u16), GFP_KERNEL);
    int     retval;

    if (!vp)
        return -ENOMEM;

    // nc_dump_registers(dev);

    if ((retval = nc_register_read(dev, REG_STATUS, vp)) < 0) {
        netdev_dbg(dev->net, "can't read %s-%s status: %d\n",
               dev->udev->bus->bus_name, dev->udev->devpath, retval);
        goto done;
    }
    status = *vp;
    nc_dump_status(dev, status);

    if ((retval = nc_register_read(dev, REG_USBCTL, vp)) < 0) {
        netdev_dbg(dev->net, "can't read USBCTL, %d\n", retval);
        goto done;
    }
    usbctl = *vp;
    nc_dump_usbctl(dev, usbctl);

    nc_register_write(dev, REG_USBCTL,
            USBCTL_FLUSH_THIS | USBCTL_FLUSH_OTHER);

    if ((retval = nc_register_read(dev, REG_TTL, vp)) < 0) {
        netdev_dbg(dev->net, "can't read TTL, %d\n", retval);
        goto done;
    }
    ttl = *vp;
    // nc_dump_ttl(dev, ttl);

    nc_register_write(dev, REG_TTL,
            MK_TTL(NC_READ_TTL_MS, TTL_OTHER(ttl)) );
    netdev_dbg(dev->net, "assigned TTL, %d ms\n", NC_READ_TTL_MS);

    netif_info(dev, link, dev->net, "port %c, peer %sconnected\n",
           (status & STATUS_PORT_A) ? 'A' : 'B',
           (status & STATUS_CONN_OTHER) ? "" : "dis");
    retval = 0;

done:
    kfree(vp);
    return retval;
}

static int net1080_check_connect(struct usbnet *dev)
{
    int         retval;
    u16         status;
    u16         *vp = kmalloc(sizeof (u16), GFP_KERNEL);

    if (!vp)
        return -ENOMEM;
    retval = nc_register_read(dev, REG_STATUS, vp);
    status = *vp;
    kfree(vp);
    if (retval != 0) {
        netdev_dbg(dev->net, "net1080_check_conn read - %d\n", retval);
        return retval;
    }
    if ((status & STATUS_CONN_OTHER) != STATUS_CONN_OTHER)
        return -ENOLINK;
    return 0;
}

static void nc_flush_complete(struct urb *urb)
{
    kfree(urb->context);
    usb_free_urb(urb);
}

static void nc_ensure_sync(struct usbnet *dev)
{
    dev->frame_errors++;
    if (dev->frame_errors > 5) {
        struct urb      *urb;
        struct usb_ctrlrequest  *req;
        int         status;

        /* Send a flush */
        urb = usb_alloc_urb(0, GFP_ATOMIC);
        if (!urb)
            return;

        req = kmalloc(sizeof *req, GFP_ATOMIC);
        if (!req) {
            usb_free_urb(urb);
            return;
        }

        req->bRequestType = USB_DIR_OUT
            | USB_TYPE_VENDOR
            | USB_RECIP_DEVICE;
        req->bRequest = REQUEST_REGISTER;
        req->wValue = cpu_to_le16(USBCTL_FLUSH_THIS
                | USBCTL_FLUSH_OTHER);
        req->wIndex = cpu_to_le16(REG_USBCTL);
        req->wLength = cpu_to_le16(0);

        /* queue an async control request, we don't need
         * to do anything when it finishes except clean up.
         */
        usb_fill_control_urb(urb, dev->udev,
            usb_sndctrlpipe(dev->udev, 0),
            (unsigned char *) req,
            NULL, 0,
            nc_flush_complete, req);
        status = usb_submit_urb(urb, GFP_ATOMIC);
        if (status) {
            kfree(req);
            usb_free_urb(urb);
            return;
        }

        netif_dbg(dev, rx_err, dev->net,
              "flush net1080; too many framing errors\n");
        dev->frame_errors = 0;
    }
}

static int net1080_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
{
    struct nc_header    *header;
    struct nc_trailer   *trailer;
    u16         hdr_len, packet_len;

    if (!(skb->len & 0x01)) {
        netdev_dbg(dev->net, "rx framesize %d range %d..%d mtu %d\n",
               skb->len, dev->net->hard_header_len, dev->hard_mtu,
               dev->net->mtu);
        dev->net->stats.rx_frame_errors++;
        nc_ensure_sync(dev);
        return 0;
    }

    header = (struct nc_header *) skb->data;
    hdr_len = le16_to_cpup(&header->hdr_len);
    packet_len = le16_to_cpup(&header->packet_len);
    if (FRAMED_SIZE(packet_len) > NC_MAX_PACKET) {
        dev->net->stats.rx_frame_errors++;
        netdev_dbg(dev->net, "packet too big, %d\n", packet_len);
        nc_ensure_sync(dev);
        return 0;
    } else if (hdr_len < MIN_HEADER) {
        dev->net->stats.rx_frame_errors++;
        netdev_dbg(dev->net, "header too short, %d\n", hdr_len);
        nc_ensure_sync(dev);
        return 0;
    } else if (hdr_len > MIN_HEADER) {
        // out of band data for us?
        netdev_dbg(dev->net, "header OOB, %d bytes\n", hdr_len - MIN_HEADER);
        nc_ensure_sync(dev);
        // switch (vendor/product ids) { ... }
    }
    skb_pull(skb, hdr_len);

    trailer = (struct nc_trailer *)
        (skb->data + skb->len - sizeof *trailer);
    skb_trim(skb, skb->len - sizeof *trailer);

    if ((packet_len & 0x01) == 0) {
        if (skb->data [packet_len] != PAD_BYTE) {
            dev->net->stats.rx_frame_errors++;
            netdev_dbg(dev->net, "bad pad\n");
            return 0;
        }
        skb_trim(skb, skb->len - 1);
    }
    if (skb->len != packet_len) {
        dev->net->stats.rx_frame_errors++;
        netdev_dbg(dev->net, "bad packet len %d (expected %d)\n",
               skb->len, packet_len);
        nc_ensure_sync(dev);
        return 0;
    }
    if (header->packet_id != get_unaligned(&trailer->packet_id)) {
        dev->net->stats.rx_fifo_errors++;
        netdev_dbg(dev->net, "(2+ dropped) rx packet_id mismatch 0x%x 0x%x\n",
               le16_to_cpu(header->packet_id),
               le16_to_cpu(trailer->packet_id));
        return 0;
    }
#if 0
    netdev_dbg(dev->net, "frame <rx h %d p %d id %d\n", header->hdr_len,
           header->packet_len, header->packet_id);
#endif
    dev->frame_errors = 0;
    return 1;
}

static struct sk_buff *
net1080_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
{
    struct sk_buff      *skb2;
    struct nc_header    *header = NULL;
    struct nc_trailer   *trailer = NULL;
    int         padlen = sizeof (struct nc_trailer);
    int         len = skb->len;

    if (!((len + padlen + sizeof (struct nc_header)) & 0x01))
        padlen++;
    if (!skb_cloned(skb)) {
        int headroom = skb_headroom(skb);
        int tailroom = skb_tailroom(skb);

        if (padlen <= tailroom &&
            sizeof(struct nc_header) <= headroom)
            /* There's enough head and tail room */
            goto encapsulate;

        if ((sizeof (struct nc_header) + padlen) <
                (headroom + tailroom)) {
            /* There's enough total room, so just readjust */
            skb->data = memmove(skb->head
                        + sizeof (struct nc_header),
                        skb->data, skb->len);
            skb_set_tail_pointer(skb, len);
            goto encapsulate;
        }
    }

    /* Create a new skb to use with the correct size */
    skb2 = skb_copy_expand(skb,
                sizeof (struct nc_header),
                padlen,
                flags);
    dev_kfree_skb_any(skb);
    if (!skb2)
        return skb2;
    skb = skb2;

encapsulate:
    /* header first */
    header = (struct nc_header *) skb_push(skb, sizeof *header);
    header->hdr_len = cpu_to_le16(sizeof (*header));
    header->packet_len = cpu_to_le16(len);
    header->packet_id = cpu_to_le16((u16)dev->xid++);

    /* maybe pad; then trailer */
    if (!((skb->len + sizeof *trailer) & 0x01))
        *skb_put(skb, 1) = PAD_BYTE;
    trailer = (struct nc_trailer *) skb_put(skb, sizeof *trailer);
    put_unaligned(header->packet_id, &trailer->packet_id);
#if 0
    netdev_dbg(dev->net, "frame >tx h %d p %d id %d\n",
           header->hdr_len, header->packet_len,
           header->packet_id);
#endif
    return skb;
}

static int net1080_bind(struct usbnet *dev, struct usb_interface *intf)
{
    unsigned    extra = sizeof (struct nc_header)
                + 1
                + sizeof (struct nc_trailer);

    dev->net->hard_header_len += extra;
    dev->rx_urb_size = dev->net->hard_header_len + dev->net->mtu;
    dev->hard_mtu = NC_MAX_PACKET;
    return usbnet_get_endpoints (dev, intf);
}

static const struct driver_info net1080_info = {
    .description =  "NetChip TurboCONNECT",
    .flags =    FLAG_POINTTOPOINT | FLAG_FRAMING_NC,
    .bind =     net1080_bind,
    .reset =    net1080_reset,
    .check_connect = net1080_check_connect,
    .rx_fixup = net1080_rx_fixup,
    .tx_fixup = net1080_tx_fixup,
};

static const struct usb_device_id   products [] = {
{
    USB_DEVICE(0x0525, 0x1080), // NetChip ref design
    .driver_info =  (unsigned long) &net1080_info,
}, {
    USB_DEVICE(0x06D0, 0x0622), // Laplink Gold
    .driver_info =  (unsigned long) &net1080_info,
},
    { },        // END
};
MODULE_DEVICE_TABLE(usb, products);

static struct usb_driver net1080_driver = {
    .name =     "net1080",
    .id_table = products,
    .probe =    usbnet_probe,
    .disconnect =   usbnet_disconnect,
    .suspend =  usbnet_suspend,
    .resume =   usbnet_resume,
    .disable_hub_initiated_lpm = 1,
};

module_usb_driver(net1080_driver);

MODULE_AUTHOR("David Brownell");
MODULE_DESCRIPTION("NetChip 1080 based USB Host-to-Host Links");
MODULE_LICENSE("GPL");