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//==========================================================================

//

//      ecos_usbeth.c

//

//      Linux device driver for eCos-based USB ethernet peripherals.

//

//==========================================================================

// ####ECOSGPLCOPYRIGHTBEGIN####                                            

// -------------------------------------------                              

// This file is part of eCos, the Embedded Configurable Operating System.   

// Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.

//

// eCos 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 or (at your option) any later      

// version.                                                                 

//

// eCos 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 eCos; if not, write to the Free Software Foundation, Inc.,    

// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.            

//

// As a special exception, if other files instantiate templates or use      

// macros or inline functions from this file, or you compile this file      

// and link it with other works to produce a work based on this file,       

// this file does not by itself cause the resulting work to be covered by   

// the GNU General Public License. However the source code for this file    

// must still be made available in accordance with section (3) of the GNU   

// General Public License v2.                                               

//

// This exception does not invalidate any other reasons why a work based    

// on this file might be covered by the GNU General Public License.         

// -------------------------------------------                              

// ####ECOSGPLCOPYRIGHTEND####                                              

//==========================================================================

//#####DESCRIPTIONBEGIN####                                             

//

// Author(s):           bartv

// Contributors:        bartv

// Date:                2000-11-12

//

//####DESCRIPTIONEND####

//==========================================================================

#include <linux/module.h>

#include <linux/init.h>

#include <linux/usb.h>

#include <linux/netdevice.h>

#include <linux/etherdevice.h>

#ifdef MODULE

MODULE_AUTHOR("Bart Veer <bartv@redhat.com>");

MODULE_DESCRIPTION("USB ethernet driver for eCos-based peripherals");

#endif

// This array identifies specific implementations of eCos USB-ethernet

// devices. All implementations should add their vendor and device

// details.

typedef struct ecos_usbeth_impl {

    const char* name;

    __u16       vendor;

    __u16       id;

} ecos_usbeth_impl;

const static ecos_usbeth_impl ecos_usbeth_implementations[] = {

    { "eCos ether",     0x4242, 0x4242 },

    { (const char*) 0,       0,      0 }

};

// Constants. These have to be kept in sync with the target-side

// code.

#define ECOS_USBETH_MAXTU                           1516

#define ECOS_USBETH_MAX_CONTROL_TU                     8

#define ECOS_USBETH_CONTROL_GET_MAC_ADDRESS         0x01

#define ECOS_USBETH_CONTROL_SET_PROMISCUOUS_MODE    0x02

// The main data structure. It keeps track of both the USB

// and network side of things, and provides buffers for

// the various operations.

//

// NOTE: currently this driver only supports a single

// plugged-in device. Theoretically multiple eCos-based

// USB ethernet devices could be plugged in to a single

// host and each one would require an ecos_usbeth

// structure.

typedef struct ecos_usbeth {

    spinlock_t                  usb_lock;

    int                         target_promiscuous;

    struct usb_device*          usb_dev;

    struct net_device*          net_dev;

    struct net_device_stats     stats;

    struct urb                  rx_urb;

    struct urb                  tx_urb;

    unsigned char               rx_buffer[ECOS_USBETH_MAXTU];

    unsigned char               tx_buffer[ECOS_USBETH_MAXTU];

} ecos_usbeth;

// open()

// Invoked by the TCP/IP stack when the interface is brought up.

// This just starts a receive operation.

static int

ecos_usbeth_open(struct net_device* net)

{

    ecos_usbeth* usbeth = (ecos_usbeth*) net->priv;

    int          res;

    netif_start_queue(net);

    res = usb_submit_urb(&(usbeth->rx_urb));

    if (0 != res) {

        printk("ecos_usbeth: failed to start USB receives, %d\n", res);

    }

    MOD_INC_USE_COUNT;

    return 0;

}

// close()

// Invoked by the TCP/IP stack when the interface is taken down.

// Any active USB operations need to be cancelled. During

// a disconnect this may get called twice, once for the

// disconnect and once for the network interface being

// brought down.

static int

ecos_usbeth_close(struct net_device* net)

{

    ecos_usbeth* usbeth = (ecos_usbeth*) net->priv;

    if (0 != netif_running(net)) {

        netif_stop_queue(net);

        net->start = 0;

        if (-EINPROGRESS == usbeth->rx_urb.status) {

            usb_unlink_urb(&(usbeth->rx_urb));

        }

        if (-EINPROGRESS == usbeth->tx_urb.status) {

            usb_unlink_urb(&(usbeth->tx_urb));

        }

        MOD_DEC_USE_COUNT;

    }

    return 0;

}

// Reception.

// probe() fills in an rx_urb. When the net device is brought up

// the urb is activated, and this callback gets run for incoming

// data.

static void

ecos_usbeth_rx_callback(struct urb* urb)

{

    ecos_usbeth*        usbeth  = (ecos_usbeth*) urb->context;

    struct net_device*  net     = usbeth->net_dev;

    struct sk_buff*     skb;

    int                 len;

    int                 res;

    if (0 != urb->status) {

        // This happens numerous times during a disconnect. Do not

        // issue a warning, but do clear the status field or things

        // get confused when resubmitting.

        //

        // Some host hardware does not distinguish between CRC errors

        // (very rare) and timeouts (perfectly normal). Do not

        // increment the error count if it might have been a timeout.

        if (USB_ST_CRC != urb->status) {

            usbeth->stats.rx_errors++;

        }

        urb->status = 0;

    } else if (2 > urb->actual_length) {

        // With some hardware the target may have to send a bogus

        // first packet. Just ignore those.

    } else {

        len = usbeth->rx_buffer[0] + (usbeth->rx_buffer[1] << 8);

        if (len > (urb->actual_length - 2)) {

            usbeth->stats.rx_errors++;

            usbeth->stats.rx_length_errors++;

            printk("ecos_usbeth: warning, packet size mismatch, got %d bytes, expected %d\n",

                   urb->actual_length, len);

        } else {

            skb = dev_alloc_skb(len + 2);

            if ((struct sk_buff*)0 == skb) {

                printk("ecos_usbeth: failed to alloc skb, dropping packet\n");

                usbeth->stats.rx_dropped++;

            } else {

#if 0

                {

                    int i;

                    printk("--------------------------------------------------------------\n");

                    printk("ecos_usbeth RX: total size %d\n", len);

                    for (i = 0; (i < len) && (i < 128); i+= 8) {

                        printk("rx  %x %x %x %x %x %x %x %x\n",

                               usbeth->rx_buffer[i+0], usbeth->rx_buffer[i+1], usbeth->rx_buffer[i+2], usbeth->rx_buffer[i+3],

                               usbeth->rx_buffer[i+4], usbeth->rx_buffer[i+5], usbeth->rx_buffer[i+6], usbeth->rx_buffer[i+7]);

                    }

                    printk("--------------------------------------------------------------\n");

                }

#endif

                skb->dev        = net;

                eth_copy_and_sum(skb, &(usbeth->rx_buffer[2]), len, 0);

                skb_put(skb, len);

                skb->protocol   = eth_type_trans(skb, net);

                netif_rx(skb);

                usbeth->stats.rx_packets++;

                usbeth->stats.rx_bytes += len;

            }

        }

    }

    if (0 != netif_running(net)) {

        res = usb_submit_urb(&(usbeth->rx_urb));

        if (0 != res) {

            printk("ecos_usbeth: failed to restart USB receives after packet, %d\n", res);

        }

    }

}

// start_tx().

// Transmit a single packet. The relevant USB protocol requires a

// 2-byte length field at the start, the incoming buffer has no space

// for this, and the URB API does not support any form of

// scatter/gather. Therefore unfortunately the whole packet has to be

// copied. The callback function is specified when the URB is filled

// in by probe().

static void

ecos_usbeth_tx_callback(struct urb* urb)

{

    ecos_usbeth* usbeth = (ecos_usbeth*) urb->context;

    spin_lock(&usbeth->usb_lock);

    if (0 != netif_running(usbeth->net_dev)) {

        netif_wake_queue(usbeth->net_dev);

    }

    spin_unlock(&usbeth->usb_lock);

}

static int

ecos_usbeth_start_tx(struct sk_buff* skb, struct net_device* net)

{

    ecos_usbeth* usbeth = (ecos_usbeth*) net->priv;

    int          res;

    if ((skb->len + 2) > ECOS_USBETH_MAXTU) {

        printk("ecos_usbeth: oversized packet of %d bytes\n", skb->len);

        return 0;

    }

    if (netif_queue_stopped(net)) {

        // Another transmission already in progress.

        // USB bulk operations should complete within 5s.

        int current_delay = jiffies - net->trans_start;

        if (current_delay < (5 * HZ)) {

            return 1;

        } else {

            // There has been a timeout. Discard this message.

            //printk("transmission timed out\n");

            usbeth->stats.tx_errors++;

            dev_kfree_skb(skb);

            return 0;

        }

    }

    spin_lock(&usbeth->usb_lock);

    usbeth->tx_buffer[0]        = skb->len & 0x00FF;

    usbeth->tx_buffer[1]        = (skb->len >> 8) & 0x00FF;

    memcpy(&(usbeth->tx_buffer[2]), skb->data, skb->len);

    usbeth->tx_urb.transfer_buffer_length = skb->len + 2;

    // Some targets are unhappy about receiving 0-length packets, not

    // just sending them.

    if (0 == (usbeth->tx_urb.transfer_buffer_length % 64)) {

        usbeth->tx_urb.transfer_buffer_length++;

    }

#if 0

    {

        int i;

        printk("--------------------------------------------------------------\n");

        printk("ecos_usbeth start_tx: len %d\n", skb->len + 2);

        for (i = 0; (i < (skb->len + 2)) && (i < 128); i+= 8) {

            printk("tx  %x %x %x %x %x %x %x %x\n",

                   usbeth->tx_buffer[i], usbeth->tx_buffer[i+1], usbeth->tx_buffer[i+2], usbeth->tx_buffer[i+3],

                   usbeth->tx_buffer[i+4], usbeth->tx_buffer[i+5], usbeth->tx_buffer[i+6], usbeth->tx_buffer[i+7]);

        }

        printk("--------------------------------------------------------------\n");

    }

#endif

    res = usb_submit_urb(&(usbeth->tx_urb));

    if (0 == res) {

        netif_stop_queue(net);

        net->trans_start        = jiffies;

        usbeth->stats.tx_packets++;

        usbeth->stats.tx_bytes  += skb->len;

    } else {

        printk("ecos_usbeth: failed to start USB packet transmission, %d\n", res);

        usbeth->stats.tx_errors++;

    }

    spin_unlock(&usbeth->usb_lock);

    dev_kfree_skb(skb);

    return 0;

}

// set_rx_mode()

// Invoked by the network stack to enable/disable promiscuous mode or

// for multicasting. The latter is not yet supported on the target

// side. The former involves a USB control message. The main call

// is not allowed to block.

static void

ecos_usbeth_set_rx_mode_callback(struct urb* urb)

{

    kfree(urb->setup_packet);

    usb_free_urb(urb);

}

static void

ecos_usbeth_set_rx_mode(struct net_device* net)

{

    ecos_usbeth* usbeth         = (ecos_usbeth*) net->priv;

    __u16        promiscuous    = net->flags & IFF_PROMISC;

    int          res;

    if (promiscuous != usbeth->target_promiscuous) {

        devrequest*     req;

        urb_t*          urb;

        urb = usb_alloc_urb(0);

        if ((urb_t*)0 == urb) {

            return;

        }

        req = kmalloc(sizeof(devrequest), GFP_KERNEL);

        if ((devrequest*)0 == req) {

            usb_free_urb(urb);

            return;

        }

        req->requesttype        = USB_TYPE_CLASS | USB_RECIP_DEVICE;

        req->request            = ECOS_USBETH_CONTROL_SET_PROMISCUOUS_MODE;

        req->value              = cpu_to_le16p(&promiscuous);

        req->index              = 0;

        req->length             = 0;

        FILL_CONTROL_URB(urb,

                         usbeth->usb_dev,

                         usb_sndctrlpipe(usbeth->usb_dev, 0),

                         (unsigned char*) req,

                         (void*) 0,

                         0,

                         &ecos_usbeth_set_rx_mode_callback,

                         (void*) usbeth);

        res = usb_submit_urb(urb);

        if (0 != res) {

            kfree(req);

            usb_free_urb(urb);

        } else {

            usbeth->target_promiscuous = promiscuous;

        }

    }

}

// netdev_stats()

// Supply the current network statistics. These are held in

// the stats field of the ecos_usbeth structure

static struct net_device_stats*

ecos_usbeth_netdev_stats(struct net_device* net)

{

    ecos_usbeth* usbeth = (ecos_usbeth*) net->priv;

    return &(usbeth->stats);

}

// ioctl()

// Currently none of the network ioctl()'s are supported

static int

ecos_usbeth_ioctl(struct net_device* net, struct ifreq* request, int command)

{

    return -EINVAL;

}

// probe().

// This is invoked by the generic USB code when a new device has

// been detected and its configuration details have been extracted

// and stored in the usbdev structure. The interface_id specifies

// a specific USB interface, to cope with multifunction peripherals.

//

// FIXME; right now this code only copes with simple enumeration data.

// OK, to be really honest it just looks for the vendor and device ids

// in the simple test cases and ignores everything else.

//

// On success it should return a non-NULL pointer, which happens to be

// a newly allocated ecos_usbeth structure. This will get passed to

// the disconnect function. Filling in the ecos_usbeth structure will,

// amongst other things, register this as a network device driver.

// The MAC address is obtained from the peripheral via a control

// request.

static void*

ecos_usbeth_probe(struct usb_device* usbdev, unsigned int interface_id)

{

    struct net_device*  net;

    ecos_usbeth*        usbeth;

    int                 res;

    unsigned char       MAC[6];

    unsigned char       dummy[1];

    int                 tx_endpoint = -1;

    int                 rx_endpoint = -1;

    const ecos_usbeth_impl*   impl;

    int                 found_impl = 0;

    // See if this is the correct driver for this USB peripheral.

    impl = ecos_usbeth_implementations;

    while (impl->name != NULL) {

        if ((usbdev->descriptor.idVendor  != impl->vendor) ||

            (usbdev->descriptor.idProduct != impl->id)) {

            found_impl = 1;

            break;

        }

        impl++;

    }

    if (! found_impl) {

        return (void*) 0;

    }

    // For now only support USB-ethernet peripherals consisting of a single

    // configuration, with a single interface, with two bulk endpoints.

    if ((1 != usbdev->descriptor.bNumConfigurations)  ||

        (1 != usbdev->config[0].bNumInterfaces) ||

        (2 != usbdev->config[0].interface[0].altsetting->bNumEndpoints)) {

        return (void*) 0;

    }

    if ((0 == (usbdev->config[0].interface[0].altsetting->endpoint[0].bEndpointAddress & USB_DIR_IN)) &&

        (0 != (usbdev->config[0].interface[0].altsetting->endpoint[1].bEndpointAddress & USB_DIR_IN))) {

        tx_endpoint = usbdev->config[0].interface[0].altsetting->endpoint[0].bEndpointAddress;

        rx_endpoint = usbdev->config[0].interface[0].altsetting->endpoint[1].bEndpointAddress & ~USB_DIR_IN;

    }

    if ((0 != (usbdev->config[0].interface[0].altsetting->endpoint[0].bEndpointAddress & USB_DIR_IN)) &&

        (0 == (usbdev->config[0].interface[0].altsetting->endpoint[1].bEndpointAddress & USB_DIR_IN))) {

        tx_endpoint = usbdev->config[0].interface[0].altsetting->endpoint[1].bEndpointAddress;

        rx_endpoint = usbdev->config[0].interface[0].altsetting->endpoint[0].bEndpointAddress & ~USB_DIR_IN;

    }

    if (-1 == tx_endpoint) {

        return (void*) 0;

    }

    res = usb_set_configuration(usbdev, usbdev->config[0].bConfigurationValue);

    if (0 != res) {

        printk("ecos_usbeth: failed to set configuration, %d\n", res);

        return (void*) 0;

    }

    res = usb_control_msg(usbdev,

                          usb_rcvctrlpipe(usbdev, 0),

                          ECOS_USBETH_CONTROL_GET_MAC_ADDRESS,

                          USB_TYPE_CLASS | USB_RECIP_DEVICE | USB_DIR_IN,

                          0,

                          0,

                          (void*) MAC,

                          6,

                          5 * HZ);

    if (6 != res) {

        printk("ecos_usbeth: failed to get MAC address, %d\n", res);

        return (void*) 0;

    }

    res = usb_control_msg(usbdev,

                          usb_sndctrlpipe(usbdev, 0),                           // pipe

                          ECOS_USBETH_CONTROL_SET_PROMISCUOUS_MODE,             // request

                          USB_TYPE_CLASS | USB_RECIP_DEVICE,                    // requesttype

                          0,                                                    // value

                          0,                                                    // index

                          (void*) dummy,                                        // data

                          0,                                                    // size

                          5 * HZ);                                              // timeout

    if (0 != res) {

        printk("ecos_usbeth: failed to disable promiscous mode, %d\n", res);

    }

    usbeth = (ecos_usbeth*) kmalloc(sizeof(ecos_usbeth), GFP_KERNEL);

    if ((ecos_usbeth*)0 == usbeth) {

        printk("ecos_usbeth: failed to allocate memory for usbeth data structure\n");

        return (void*) 0;

    }

    memset(usbeth, 0, sizeof(ecos_usbeth));

    net                 = init_etherdev(0, 0);

    if ((struct net_device*) 0 == net) {

        kfree(usbeth);

        printk("ecos_usbeth: failed to allocate memory for net data structure\n");

        return (void*) 0;

    }

    usbeth->usb_lock    = SPIN_LOCK_UNLOCKED;

    usbeth->usb_dev     = usbdev;

    FILL_BULK_URB(&(usbeth->tx_urb), usbdev, usb_sndbulkpipe(usbdev, tx_endpoint),

                  usbeth->tx_buffer, ECOS_USBETH_MAXTU, &ecos_usbeth_tx_callback, (void*) usbeth);

    FILL_BULK_URB(&(usbeth->rx_urb), usbdev, usb_rcvbulkpipe(usbdev, rx_endpoint),

                  usbeth->rx_buffer, ECOS_USBETH_MAXTU, &ecos_usbeth_rx_callback, (void*) usbeth);

    usbeth->net_dev             = net;

    usbeth->target_promiscuous  = 0;

    net->priv                   = (void*) usbeth;

    net->open                   = &ecos_usbeth_open;

    net->stop                   = &ecos_usbeth_close;

    net->do_ioctl               = &ecos_usbeth_ioctl;

    net->hard_start_xmit        = &ecos_usbeth_start_tx;

    net->set_multicast_list     = &ecos_usbeth_set_rx_mode;

    net->get_stats              = &ecos_usbeth_netdev_stats;

    net->mtu                    = 1500; // ECOS_USBETH_MAXTU - 2;

    memcpy(net->dev_addr, MAC, 6);

    printk("eCos-based USB ethernet peripheral active at %s\n", net->name);

    MOD_INC_USE_COUNT;

    return (void*) usbeth;

}

// disconnect().

// Invoked after probe() has recognized a device but that device

// has gone away. 

static void

ecos_usbeth_disconnect(struct usb_device* usbdev, void* data)

{

    ecos_usbeth* usbeth = (ecos_usbeth*) data;

    if (!usbeth) {

        printk("ecos_usbeth: warning, disconnecting unconnected device\n");

        return;

    }

    if (0 != netif_running(usbeth->net_dev)) {

        ecos_usbeth_close(usbeth->net_dev);

    }

    unregister_netdev(usbeth->net_dev);

    if (-EINPROGRESS == usbeth->rx_urb.status) {

        usb_unlink_urb(&(usbeth->rx_urb));

    }

    if (-EINPROGRESS == usbeth->tx_urb.status) {

        usb_unlink_urb(&(usbeth->tx_urb));

    }

    kfree(usbeth);

    MOD_DEC_USE_COUNT;

}

static struct usb_driver ecos_usbeth_driver = {

    name:       "ecos_usbeth",

    probe:      ecos_usbeth_probe,

    disconnect: ecos_usbeth_disconnect,

};

// init()

// Called when the module is loaded. It just registers the device with

// the generic USB code. Nothing else can really be done until

// the USB code detects that a device has been attached.

int __init

ecos_usbeth_init(void)

{

    printk("eCos USB-ethernet device driver\n");

    return usb_register(&ecos_usbeth_driver);

}

// exit()

// Called when the module is unloaded. disconnect() will be

// invoked if appropriate.

void __exit

ecos_usbeth_exit(void)

{

    usb_deregister(&ecos_usbeth_driver);

}

module_init(ecos_usbeth_init);

module_exit(ecos_usbeth_exit);