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

//

//      usbethdrv.c

//

//      Network device driver for USB-ethernet devices.

//

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

//####ECOSGPLCOPYRIGHTBEGIN####

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

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

// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, 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.,

// 59 Temple Place, Suite 330, Boston, MA 02111-1307 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.

//

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

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

//

// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.

// at http://sources.redhat.com/ecos/ecos-license/

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

//####ECOSGPLCOPYRIGHTEND####

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

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

//

// Author(s):    bartv

// Contributors: bartv

// Date:         2000-10-04

//

//####DESCRIPTIONEND####

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

#include <cyg/infra/cyg_type.h>

#include <cyg/hal/hal_arch.h>

#include <cyg/infra/diag.h>

#include <cyg/hal/drv_api.h>

#define __ECOS 1

#include <cyg/io/eth/netdev.h>

#include <cyg/io/eth/eth_drv.h>

#include <cyg/io/eth/eth_drv_stats.h>

#include <pkgconf/io_usb_slave_eth.h>

#include <cyg/io/usb/usbs_eth.h>

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

// The network driver data structure.

ETH_DRV_SC(usbs_eth_sc0,

           (void*) &usbs_eth0,

           CYGDAT_USBS_ETHDRV_NAME,

           usbs_ethdrv_start,

           usbs_ethdrv_stop,

           usbs_ethdrv_ioctl,

           usbs_ethdrv_can_send,

           usbs_ethdrv_send,

           usbs_ethdrv_recv,

           usbs_ethdrv_deliver,

           usbs_ethdrv_poll,

           usbs_ethdrv_intvector);

NETDEVTAB_ENTRY(usbs_eth_netdev0,

                "usbs_eth0",

                usbs_ethdrv_init,

                &usbs_eth_sc0);

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

// Statics gathering. The following macro can be used to increment a

// statistic without having to use a #ifdef for the statistics

// configuration option everywhere.

#ifdef CYGFUN_USBS_ETHDRV_STATISTICS

# define INCR_STAT(a)   \

     CYG_MACRO_START    \

     (a) += 1;          \

     CYG_MACRO_END

#else

# define INCR_STAT(a)      CYG_EMPTY_STATEMENT

#endif

// Various constants related to SNMP statistics. It is not clear

// what these are all for.

#ifdef CYGFUN_USBS_ETHDRV_STATISTICS

# define CYGDAT_USBS_ETHDRV_DESCRIPTION "eCos USB ethernet device"

#endif

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

// Utility functions.

//

// The TCP/IP stack works in terms of scatter/gather buffers. USB tends to

// involve DMA operations so it is more convenient to work in terms of

// 1514 byte flat buffers. Actually, the first two bytes of the buffer

// are used to hold the ethernet frame size to work around restrictions

// with certain hardware implementations of USB that may be unable to

// transfer certain packet sizes.

static bool

scatter(unsigned char* buf, struct eth_drv_sg* sg, int sg_len)

{

    unsigned int size;

    size = buf[0] | (buf[1] << 8);

    buf++; buf++;

    CYG_ASSERT((size >= CYGNUM_USBS_ETH_MIN_FRAME_SIZE) && (size <= CYGNUM_USBS_ETH_MAX_FRAME_SIZE),\

               "ethernet frame size limits must be observed");

    while ((size > 0) && (sg_len > 0)) {

        if (size > sg->len) {

            memcpy((void*) sg->buf, buf, sg->len);

            buf  += sg->len;

            size -= sg->len;

            sg++;

            sg_len--;

        } else {

            memcpy((void*) sg->buf, buf, size);

            size = 0;

        }

    }

    return 0 == size;

}

static bool

gather(unsigned char* buf, unsigned int size, struct eth_drv_sg* sg, int sg_len)

{

    unsigned int    left = size;

    unsigned char*  base = buf;

    buf++; buf++;

    while ((left > 0) && (sg_len > 0)) {

        if (left > sg->len) {

            memcpy(buf, (void*) sg->buf, sg->len);

            buf  += sg->len;

            left -= sg->len;

            sg++;

            sg_len--;

        } else {

            memcpy(buf, (void*) sg->buf, left);

            left = 0;

        }

    }

    size    = size - left;

    base[0] = size & 0x00FF;

    base[1] = (size >> 8) & 0x00FF;

    return 0 == left;

}

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

// usbs_ethdrv_init()

//

// This function is called during system initialization to decide

// whether or not this particular network device is usable. For

// USB-ethernet this is problematical, the device is only really

// usable once both sides have come up. The typical sequence

// of events is something like:

//

// 1) the eCos peripheral is powered up. Static constructors are

//    run resulting in basic initialization.

//

// 2) the eCos TCP/IP stack initialization happens. Roughly in

//    parallel the eCos USB slave side is initialized as well,

//    i.e. enumeration data is supplied to control endpoints,

//    endpoints are associated with application classes, and so

//    on. The relative order of TCP/IP and USB initialization is

//    not particularly important.

//

//    It is the TCP/IP stack's initialization code that will

//    invoke usbs_eth_init().

//

// 3) host-side USB detects that the eCos peripheral has been

//    connected or powered up. It goes through the enumeration

//    process and will end up loading a host-side network driver.

//    This connects to the eCos-side USB ethernet code to

//    e.g. obtain the MAC address. 

//

// 4) when the host-side is ready, the eCos side can be brought up.

//    The required call is (sc->funs->eth_drv->init)(sc, enaddr)

//

// In practice it is easier for now to invoke the init() function

// immediately. There are not going to be any incoming packets

// until the host is ready, and can_send() can just return false

// for the time being.

//

// Invoked in: thread context only

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

static bool

usbs_ethdrv_init(struct cyg_netdevtab_entry* ndp)

{

    struct eth_drv_sc*  sc  = (struct eth_drv_sc*)(ndp->device_instance);

    usbs_eth*           eth = (usbs_eth*)(sc->driver_private);

    (*sc->funs->eth_drv->init)(sc, eth->ecos_MAC);

    return true;

}

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

// The receive process that is used to transfer a received ethernet

// packet into the stack. The calling sequence is somewhat convoluted.

// It started off as:

//

//   1) Ethernet hw ISR invoked by hardware, schedules its own

//      hw_dsr(), and blocks further interrupts in the ethernet chip

//   2) hw_dsr() calls generic eth_drv_dsr() from io/eth common package

//   3) eth_drv_dsr() interacts with the TCP/IP stack and allocates mbufs

//      (typically, the TCP/IP stack might not be in use)

//   4) eth_drv_dsr() calls usbs_eth_recv() to transfer the data to mbufs

//   5) eth_drv_dsr() returns to hw_dsr() which reenables interrupts

//   6) hw_dsr() completes and everything can proceed.

//

// The problem with this is that the whole ethernet packet gets copied

// inside a DSR, affecting dispatch latency (but not interrupt latency).

// This is bad. Hence there is an alternative route involving a separate

// thread in the TCP/IP stack.

//

//   1) Ethernet hw ISR runs as before, scheduling hw_dsr()

//   2) hw_dsr() calls up into eth_drv_dsr()

//   3) eth_drv_dsr() wakes up a thread inside the TCP/IP stack

//   4) eth_drv_dsr() returns to hw_dsr(), which performs no further

//      processing. Ethernet chip interrupts remain disabled.

//   5) The TCP/IP thread ends up calling hw_deliver(). This should take

//      care of any pending activity. For every buffered packet there should

//      be a call to a generic recv() function which then goes back into

//      the driver-specific recv() function.

//

// The advantage is that ethernet packet copying now happens at thread

// level rather than DSR level so thread priorities can be used to

// schedule things.

//

// USB-ethernet does not interact directly with any hardware, instead

// it just passes information to lower levels of USB code. The reception

// process is started by usbs_ethdrv_start() when the TCP/IP stack brings

// up the interface. 

//

// When the USB transfer has completed a callback will be invoked, at

// DSR level. Assuming the transfer went ok, the callback will invoke

// eth_drv_dsr() to inform the higher level code. 

//

// The deliver function can check the state of the buffer

// and go through the sc->funs->eth_drv->recv()/recv() sequence

// to transfer the data into the stack. 

//

// usbs_ethdrv_recv() does a scatter from the internal buffer into the

// mbuf, thus freeing up the buffer. This allows it to start another

// receive,

//

// Synchronisation involves the scheduler lock because the recv

// callback is invoked inside a DSR.

static void usbs_ethdrv_halted_callback(void*, int);

static void

usbs_ethdrv_recv_callback(usbs_eth* eth, void* callback_data, int size)

{

    cyg_bool resubmit = true;

    struct eth_drv_sc* sc = (struct eth_drv_sc*) callback_data;

    CYG_ASSERT( eth == (usbs_eth*)(sc->driver_private), "USB and TCP/IP worlds need to be consistent");

    INCR_STAT(eth->interrupts);

    if (!eth->ecos_up) {

        // This message should just be discarded since the eCos TCP/IP

        // stack is not expecting anything from this interface.

        // Reception will resume when the interface comes back up.

        eth->rx_active  = false;

        resubmit        = false;

    } else if (size < 0) {

        // An error has occurred. The likely possibilities are:

        // -EPIPE:      connection to the host has been broken

        // -EAGAIN:     the endpoint is haltedn

        // -EMSGSIZE:   bogus message from host

        // -EIO:        other

        if (-EAGAIN == size) {

            // EAGAIN should be handled by waiting for the endpoint to be reset.

            resubmit = false;

            usbs_start_rx_endpoint_wait(eth->rx_endpoint, &usbs_ethdrv_halted_callback, (void*) sc);

        } else if (-EMSGSIZE == size) {

            // Do nothing for now

        } else {

            // EPIPE should be resubmitted, the usbseth.c will use the

            // pending rx support. EIO could mean anything.

        }

    } else if (0 == size) {

        // The endpoint is no longer halted. Just do the resubmit at

        // the end.

    } else {

        // A packet has been received. Now do a size sanity check

        // based on the first two bytes.

        int real_size = eth->rx_bufptr[0] + (eth->rx_bufptr[1] << 8);

        if (real_size < CYGNUM_USBS_ETH_MIN_FRAME_SIZE) {

            INCR_STAT(eth->rx_short_frames);

        } else if (real_size > CYGNUM_USBS_ETH_MAX_FRAME_SIZE) {

            INCR_STAT(eth->rx_too_long_frames);

        } else {

            // The packet appears to be valid. Inform higher level

            // code and mark the buffer as in use.

            resubmit            = false;

            eth->rx_buffer_full = true;

            eth->rx_active      = false;

            eth_drv_dsr(0, 0, (cyg_addrword_t) sc);

        }

    }

    if (resubmit) {

        eth->rx_active = true;

        usbs_eth_start_rx(eth, eth->rx_bufptr, &usbs_ethdrv_recv_callback, callback_data);

    }

}

// Another callback, used to wait while an endpoint is halted.

static void

usbs_ethdrv_halted_callback(void* callback_data, int size)

{

    struct eth_drv_sc* sc = (struct eth_drv_sc*) callback_data;

    usbs_ethdrv_recv_callback((usbs_eth*) sc->driver_private, callback_data, 0);

}

// Start a receive operation. It is not possible to abort an existing

// rx operation, so a valid sequence of events is: start, rx ongoing,

// stop, restart. The rx_active field is used to keep track of whether

// or not there is still a receive in progress. The receive callback

// will just discard incoming data if the eCos stack is not currently

// running.

static void

usbs_ethdrv_start_recv(struct eth_drv_sc* sc, usbs_eth* eth)

{

    cyg_drv_dsr_lock();

    if (!eth->rx_active) {

        eth->rx_active = true;

        usbs_eth_start_rx(eth, eth->rx_bufptr, &usbs_ethdrv_recv_callback, (void*) sc);

    }

    cyg_drv_dsr_unlock();

}

// This is invoked from the delivery thread when a valid buffer

// has been received. The buffer should be scattered into the

// supplied list, then another receive should be started.

static void

usbs_ethdrv_recv(struct eth_drv_sc* sc,

                 struct eth_drv_sg* sg_list, int sg_len)

{

    usbs_eth* eth = (usbs_eth*)(sc->driver_private);

    CYG_ASSERT( eth->rx_buffer_full, "This function should only be called when there is a buffer available");

    (void) scatter(eth->rx_bufptr, sg_list, sg_len);

    eth->rx_buffer_full = false;

    eth->rx_active      = true;

    usbs_eth_start_rx(eth, eth->rx_bufptr, &usbs_ethdrv_recv_callback, (void*) sc);

}

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

// Now for the transmit process.

//

// When an application thread writes down a socket the data gets moved

// into mbufs, and then passed to the appropriate device driver - which

// may or may not be able to process it immediately. There is also a

// timeout thread within the TCP/IP to handle retransmits etc.

//

// The stack will start by calling usbs_ethdrv_can_send() to determine

// whether or not the driver can accept the packet. For the purposes

// of the USB-ethernet driver this is true provided both host

// and target are up and there is a spare buffer available.

//

// If the usbs_eth_can_send() returns true then there will be a call

// to usbs_ethdrv_send(). This gathers the data into a single

// buffer. If there is no transmit in progress yet then one is started.

//

// At some point the packet will have been transmitted and a callback

// gets invoked. This needs to call eth_drv_dsr(), waking up the

// delivery thread. The deliver() function can then check which

// transmissions have completed and inform the higher level code

// via sc->funs->eth_drv->tx_done(). The buffer can be re-used at

// that point.

static void

usbs_ethdrv_send_callback(usbs_eth* eth, void* callback_data, int size)

{

    struct eth_drv_sc* sc = (struct eth_drv_sc*) callback_data;

    CYG_ASSERT( eth == (usbs_eth*)(sc->driver_private), "USB and TCP/IP worlds need to be consistent");

    INCR_STAT(eth->interrupts);

    // There are a variety of possible error codes. -EAGAIN indicates

    // that the endpoint is stalled. -EPIPE indicates that the

    // connection to the host has been lost. These are not really

    // particularly interesting. Whatever happens the buffer

    // must be cleared and higher-level code informed so that

    // the mbufs can be released.

    if (size > 0) {

        INCR_STAT(eth->tx_count);

    }

    eth->tx_done = true;

    eth_drv_dsr(0, 0, (cyg_addrword_t) sc);

}

// Is it possible to send an ethernet frame? This requires

// an empty buffer, i.e. there should be no existing

// transmit in progress. It also requires that the host

// is connected and that the endpoint is not currently halted.

static int

usbs_ethdrv_can_send(struct eth_drv_sc* sc)

{

    usbs_eth* eth = (usbs_eth*)(sc->driver_private);

    return eth->host_up && !eth->tx_buffer_full && !eth->tx_endpoint->halted;

}

// Actually start a packet transmission. This means collecting

// all the data into a single buffer and then invoking the

// lower-level code. The latter may discard the packet immediately

// if the MAC is not appropriate: it would be more efficient to

// catch that here, especially for large packets, but the check

// has to happen inside the lower-level code anyway in case

// that is being invoked directly rather than via the driver.

//

// There is a possible recursion problem,

// send->start_tx->tx_done->can_send->send, which is guarded

// against using the tx_in_send flag.

static void

usbs_ethdrv_send(struct eth_drv_sc* sc,

              struct eth_drv_sg* sgl_list, int sg_len, int total_len,

              unsigned long key)

{

    usbs_eth* eth = (usbs_eth*)(sc->driver_private);

    CYG_ASSERT( 0 == eth->tx_in_send, "send() should not be invoked recursively");

    CYG_ASSERT( total_len <= CYGNUM_USBS_ETH_MAX_FRAME_SIZE, "ethernet maximum frame size should be observed");

    CYG_ASSERT( CYGNUM_USBS_ETH_MIN_FRAME_SIZE <= total_len, "ethernet minimum frame size should be observed");

    eth->tx_in_send = true;

    CYG_ASSERT( !eth->tx_buffer_full, "the transmit buffer should be empty");

    gather(eth->tx_buffer, CYGNUM_USBS_ETH_MAX_FRAME_SIZE, sgl_list, sg_len);

    eth->tx_buffer_full = true;

    eth->tx_done        = false;

    eth->tx_key         = key;

    usbs_eth_start_tx(eth, eth->tx_buffer, &usbs_ethdrv_send_callback, (void*) sc);

    eth->tx_in_send = false;

}

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

// Deliver needs to take into account both receive and transmit buffers.

static void

usbs_ethdrv_deliver(struct eth_drv_sc* sc)

{

    usbs_eth* eth = (usbs_eth*)(sc->driver_private);

    if (eth->rx_buffer_full) {

        int size = eth->rx_bufptr[0] + (eth->rx_bufptr[1] << 8);

        (*sc->funs->eth_drv->recv)(sc, size);

    }

    if (eth->tx_done) {

        unsigned long key   = eth->tx_key;

        eth->tx_buffer_full = false;

        eth->tx_done        = false;

        (*sc->funs->eth_drv->tx_done)(sc, key, 1);

    }

}

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

// usbs_ethdrv_start()

//

// This gets called by the TCP/IP stack later on during

// initialization, when the stack is ready to send and receive

// packets. It may get called multiple times while the stack

// is running, with different flags values.

//

// As far as transmits are concerned, nothing needs to be done. If no

// transmit is in progress then everything is fine anyway. If a

// transmit is already in progress then it must be allowed to complete

// via the usual route. Receives should however be restarted, the

// start function has appropriate safeguards.

//

// Invoked in: thread context only

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

static void

usbs_ethdrv_start(struct eth_drv_sc* sc, unsigned char* enaddr, int flags)

{

    usbs_eth* eth = (usbs_eth*)(sc->driver_private);

    if (!eth->ecos_up) {

        eth->ecos_up = true;

        usbs_ethdrv_start_recv(sc, eth);

    }

}

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

// usbs_ethdrv_stop()

//

// Similarly this gets called by the TCP/IP stack to bring the network

// interface down. Nothing should happen for any packets currently

// being transmitted or received, that would cause confusion everywhere.

// The receive callback checks the ecos_up flag and does the right

// thing. The TCP/IP stack should not call can_send() after taking

// the interface down so no new transmits will be initiated.

//

// Invoked in: thread context only

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

static void

usbs_ethdrv_stop(struct eth_drv_sc* sc)

{

    usbs_eth* eth = (usbs_eth*)(sc->driver_private);

    eth->ecos_up = false;

}

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

// usbs_eth_ioctl()

//

// The operations to worry about here are:

//

//    SET_MAC_ADDRESS,via the SIOCSIFHWADDR ioctl

//

//    GET_IF_STATS and GET_IF_STATS_UD, to report gathered statistics.

//

// Invoked in: thread context only

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

static int

usbs_ethdrv_ioctl(struct eth_drv_sc* sc, unsigned long key, void* data, int data_length)

{

    usbs_eth* eth = (usbs_eth*)(sc->driver_private);

    int       result = EINVAL;

    switch(key) {

      case ETH_DRV_SET_MAC_ADDRESS:

        {

            if (6 == data_length) {

                memcpy(eth->ecos_MAC, data, 6);

                result = 0;

            }

        }

        break;

#if defined(CYGFUN_USBS_ETHDRV_STATISTICS) && defined(ETH_DRV_GET_IF_STATS_UD)

      case ETH_DRV_GET_IF_STATS_UD:

      case ETH_DRV_GET_IF_STATS:

        {

            static unsigned char my_chipset[] = { 0, 0 };

            struct ether_drv_stats *p = (struct ether_drv_stats*) data;

            int    i;

            strcpy(p->description, CYGDAT_USBS_ETHDRV_DESCRIPTION);

            for ( i = 0; i < SNMP_CHIPSET_LEN; i++ ) {

                if ( 0 == (p->snmp_chipset[i] = my_chipset[i]) ) {

                    break;

                }

            }

            p->duplex               = 3;        // 3 == duplex

            p->operational          = (eth->host_up && eth->ecos_up) ? 3 : 2;   // 3 == up, 2 == down

            p->speed                = 10 * 1000000;

            p->supports_dot3        = 1;

            p->rx_too_long_frames   = eth->rx_too_long_frames;

            p->rx_short_frames      = eth->rx_short_frames;

            p->interrupts           = eth->interrupts;

            p->rx_count             = eth->rx_count;

            p->tx_count             = eth->tx_count;

            p->tx_queue_len         = 1;

        }

        break;

#endif

      default:

        break;

    }

    return result;

}

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

// usbs_ethdrv_poll()

//

// On real ethernet hardware this is used by RedBoot once the

// application has started running, so that the network device can be

// used for debugging purposes as well as for the application's own

// needs. The lower-level USB device may supply a poll function as well.

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

static void

usbs_ethdrv_poll(struct eth_drv_sc* sc)

{

    usbs_eth*   eth = (usbs_eth*)(sc->driver_private);

    (*eth->control_endpoint->poll_fn)(eth->control_endpoint);

}

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

// usbs_ethdrv_intvector()

//

// See usbs_eth_poll().

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

static int

usbs_ethdrv_intvector(struct eth_drv_sc* sc)

{

    usbs_eth*   eth = (usbs_eth*)(sc->driver_private);

    return eth->control_endpoint->interrupt_vector;

}