cx82310_eth.c

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/*
 * Driver for USB ethernet port of Conexant CX82310-based ADSL routers
 * Copyright (C) 2010 by Ondrej Zary
 * some parts inspired by the cxacru driver
 *
 * 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
 */

#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>

enum cx82310_cmd {
    CMD_START       = 0x84, /* no effect? */
    CMD_STOP        = 0x85, /* no effect? */
    CMD_GET_STATUS      = 0x90, /* returns nothing? */
    CMD_GET_MAC_ADDR    = 0x91, /* read MAC address */
    CMD_GET_LINK_STATUS = 0x92, /* not useful, link is always up */
    CMD_ETHERNET_MODE   = 0x99, /* unknown, needed during init */
};

enum cx82310_status {
    STATUS_UNDEFINED,
    STATUS_SUCCESS,
    STATUS_ERROR,
    STATUS_UNSUPPORTED,
    STATUS_UNIMPLEMENTED,
    STATUS_PARAMETER_ERROR,
    STATUS_DBG_LOOPBACK,
};

#define CMD_PACKET_SIZE 64
/* first command after power on can take around 8 seconds */
#define CMD_TIMEOUT 15000
#define CMD_REPLY_RETRY 5

#define CX82310_MTU 1514
#define CMD_EP      0x01

/*
 * execute control command
 *  - optionally send some data (command parameters)
 *  - optionally wait for the reply
 *  - optionally read some data from the reply
 */
static int cx82310_cmd(struct usbnet *dev, enum cx82310_cmd cmd, bool reply,
               u8 *wdata, int wlen, u8 *rdata, int rlen)
{
    int actual_len, retries, ret;
    struct usb_device *udev = dev->udev;
    u8 *buf = kzalloc(CMD_PACKET_SIZE, GFP_KERNEL);

    if (!buf)
        return -ENOMEM;

    /* create command packet */
    buf[0] = cmd;
    if (wdata)
        memcpy(buf + 4, wdata, min_t(int, wlen, CMD_PACKET_SIZE - 4));

    /* send command packet */
    ret = usb_bulk_msg(udev, usb_sndbulkpipe(udev, CMD_EP), buf,
               CMD_PACKET_SIZE, &actual_len, CMD_TIMEOUT);
    if (ret < 0) {
        dev_err(&dev->udev->dev, "send command %#x: error %d\n",
            cmd, ret);
        goto end;
    }

    if (reply) {
        /* wait for reply, retry if it's empty */
        for (retries = 0; retries < CMD_REPLY_RETRY; retries++) {
            ret = usb_bulk_msg(udev, usb_rcvbulkpipe(udev, CMD_EP),
                       buf, CMD_PACKET_SIZE, &actual_len,
                       CMD_TIMEOUT);
            if (ret < 0) {
                dev_err(&dev->udev->dev,
                    "reply receive error %d\n", ret);
                goto end;
            }
            if (actual_len > 0)
                break;
        }
        if (actual_len == 0) {
            dev_err(&dev->udev->dev, "no reply to command %#x\n",
                cmd);
            ret = -EIO;
            goto end;
        }
        if (buf[0] != cmd) {
            dev_err(&dev->udev->dev,
                "got reply to command %#x, expected: %#x\n",
                buf[0], cmd);
            ret = -EIO;
            goto end;
        }
        if (buf[1] != STATUS_SUCCESS) {
            dev_err(&dev->udev->dev, "command %#x failed: %#x\n",
                cmd, buf[1]);
            ret = -EIO;
            goto end;
        }
        if (rdata)
            memcpy(rdata, buf + 4,
                   min_t(int, rlen, CMD_PACKET_SIZE - 4));
    }
end:
    kfree(buf);
    return ret;
}

#define partial_len data[0]     /* length of partial packet data */
#define partial_rem data[1]     /* remaining (missing) data length */
#define partial_data    data[2]     /* partial packet data */

static int cx82310_bind(struct usbnet *dev, struct usb_interface *intf)
{
    int ret;
    char buf[15];
    struct usb_device *udev = dev->udev;

    /* avoid ADSL modems - continue only if iProduct is "USB NET CARD" */
    if (usb_string(udev, udev->descriptor.iProduct, buf, sizeof(buf)) > 0
        && strcmp(buf, "USB NET CARD")) {
        dev_info(&udev->dev, "ignoring: probably an ADSL modem\n");
        return -ENODEV;
    }

    ret = usbnet_get_endpoints(dev, intf);
    if (ret)
        return ret;

    /*
     * this must not include ethernet header as the device can send partial
     * packets with no header (and sometimes even empty URBs)
     */
    dev->net->hard_header_len = 0;
    /* we can send at most 1514 bytes of data (+ 2-byte header) per URB */
    dev->hard_mtu = CX82310_MTU + 2;
    /* we can receive URBs up to 4KB from the device */
    dev->rx_urb_size = 4096;

    dev->partial_data = (unsigned long) kmalloc(dev->hard_mtu, GFP_KERNEL);
    if (!dev->partial_data)
        return -ENOMEM;

    /* enable ethernet mode (?) */
    ret = cx82310_cmd(dev, CMD_ETHERNET_MODE, true, "\x01", 1, NULL, 0);
    if (ret) {
        dev_err(&udev->dev, "unable to enable ethernet mode: %d\n",
            ret);
        goto err;
    }

    /* get the MAC address */
    ret = cx82310_cmd(dev, CMD_GET_MAC_ADDR, true, NULL, 0,
              dev->net->dev_addr, ETH_ALEN);
    if (ret) {
        dev_err(&udev->dev, "unable to read MAC address: %d\n", ret);
        goto err;
    }

    /* start (does not seem to have any effect?) */
    ret = cx82310_cmd(dev, CMD_START, false, NULL, 0, NULL, 0);
    if (ret)
        goto err;

    return 0;
err:
    kfree((void *)dev->partial_data);
    return ret;
}

static void cx82310_unbind(struct usbnet *dev, struct usb_interface *intf)
{
    kfree((void *)dev->partial_data);
}

/*
 * RX is NOT easy - we can receive multiple packets per skb, each having 2-byte
 * packet length at the beginning.
 * The last packet might be incomplete (when it crosses the 4KB URB size),
 * continuing in the next skb (without any headers).
 * If a packet has odd length, there is one extra byte at the end (before next
 * packet or at the end of the URB).
 */
static int cx82310_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
{
    int len;
    struct sk_buff *skb2;

    /*
     * If the last skb ended with an incomplete packet, this skb contains
     * end of that packet at the beginning.
     */
    if (dev->partial_rem) {
        len = dev->partial_len + dev->partial_rem;
        skb2 = alloc_skb(len, GFP_ATOMIC);
        if (!skb2)
            return 0;
        skb_put(skb2, len);
        memcpy(skb2->data, (void *)dev->partial_data,
               dev->partial_len);
        memcpy(skb2->data + dev->partial_len, skb->data,
               dev->partial_rem);
        usbnet_skb_return(dev, skb2);
        skb_pull(skb, (dev->partial_rem + 1) & ~1);
        dev->partial_rem = 0;
        if (skb->len < 2)
            return 1;
    }

    /* a skb can contain multiple packets */
    while (skb->len > 1) {
        /* first two bytes are packet length */
        len = skb->data[0] | (skb->data[1] << 8);
        skb_pull(skb, 2);

        /* if last packet in the skb, let usbnet to process it */
        if (len == skb->len || len + 1 == skb->len) {
            skb_trim(skb, len);
            break;
        }

        if (len > CX82310_MTU) {
            dev_err(&dev->udev->dev, "RX packet too long: %d B\n",
                len);
            return 0;
        }

        /* incomplete packet, save it for the next skb */
        if (len > skb->len) {
            dev->partial_len = skb->len;
            dev->partial_rem = len - skb->len;
            memcpy((void *)dev->partial_data, skb->data,
                   dev->partial_len);
            skb_pull(skb, skb->len);
            break;
        }

        skb2 = alloc_skb(len, GFP_ATOMIC);
        if (!skb2)
            return 0;
        skb_put(skb2, len);
        memcpy(skb2->data, skb->data, len);
        /* process the packet */
        usbnet_skb_return(dev, skb2);

        skb_pull(skb, (len + 1) & ~1);
    }

    /* let usbnet process the last packet */
    return 1;
}

/* TX is easy, just add 2 bytes of length at the beginning */
static struct sk_buff *cx82310_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
                       gfp_t flags)
{
    int len = skb->len;

    if (skb_headroom(skb) < 2) {
        struct sk_buff *skb2 = skb_copy_expand(skb, 2, 0, flags);
        dev_kfree_skb_any(skb);
        skb = skb2;
        if (!skb)
            return NULL;
    }
    skb_push(skb, 2);

    skb->data[0] = len;
    skb->data[1] = len >> 8;

    return skb;
}


static const struct driver_info cx82310_info = {
    .description    = "Conexant CX82310 USB ethernet",
    .flags      = FLAG_ETHER,
    .bind       = cx82310_bind,
    .unbind     = cx82310_unbind,
    .rx_fixup   = cx82310_rx_fixup,
    .tx_fixup   = cx82310_tx_fixup,
};

static const struct usb_device_id products[] = {
    {
        USB_DEVICE_AND_INTERFACE_INFO(0x0572, 0xcb01, 0xff, 0, 0),
        .driver_info = (unsigned long) &cx82310_info
    },
    { },
};
MODULE_DEVICE_TABLE(usb, products);

static struct usb_driver cx82310_driver = {
    .name       = "cx82310_eth",
    .id_table   = products,
    .probe      = usbnet_probe,
    .disconnect = usbnet_disconnect,
    .suspend    = usbnet_suspend,
    .resume     = usbnet_resume,
    .disable_hub_initiated_lpm = 1,
};

module_usb_driver(cx82310_driver);

MODULE_AUTHOR("Ondrej Zary");
MODULE_DESCRIPTION("Conexant CX82310-based ADSL router USB ethernet driver");
MODULE_LICENSE("GPL");