/******************************************************************************
 *
 *  $Id$
 *
 *  Copyright (C) 2006  Florian Pose, Ingenieurgemeinschaft IgH
 *
 *  This file is part of the IgH EtherCAT Master.
 *
 *  The IgH EtherCAT Master 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.
 *
 *  The IgH EtherCAT Master 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 the IgH EtherCAT Master; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 *  The right to use EtherCAT Technology is granted and comes free of
 *  charge under condition of compatibility of product made by
 *  Licensee. People intending to distribute/sell products based on the
 *  code, have to sign an agreement to guarantee that products using
 *  software based on IgH EtherCAT master stay compatible with the actual
 *  EtherCAT specification (which are released themselves as an open
 *  standard) as the (only) precondition to have the right to use EtherCAT
 *  Technology, IP and trade marks.
 *
 *****************************************************************************/

/**
   \file
   EtherCAT device methods.
*/

/*****************************************************************************/

#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/if_ether.h>
#include <linux/netdevice.h>

#include "device.h"
#include "master.h"

#ifdef EC_DEBUG_RING
#define timersub(a, b, result) \
    do { \
        (result)->tv_sec = (a)->tv_sec - (b)->tv_sec; \
        (result)->tv_usec = (a)->tv_usec - (b)->tv_usec; \
        if ((result)->tv_usec < 0) { \
            --(result)->tv_sec; \
            (result)->tv_usec += 1000000; \
        } \
    } while (0)
#endif

/*****************************************************************************/

/**
   Device constructor.
   \return 0 in case of success, else < 0
*/

int ec_device_init(ec_device_t *device, /**< EtherCAT device */
        ec_master_t *master /**< master owning the device */
        )
{
    unsigned int i;
    struct ethhdr *eth;
#ifdef EC_DEBUG_IF
    char ifname[10];
    char mb = 'x';
#endif
#ifdef EC_DEBUG_RING
    device->debug_frame_index = 0;
    device->debug_frame_count = 0;
#endif

    device->master = master;
    device->tx_ring_index = 0;

#ifdef EC_DEBUG_IF
    if (device == &master->main_device)
        mb = 'm';
    else if (device == &master->backup_device)
        mb = 'b';

    sprintf(ifname, "ecdbg%c%u", mb, master->index);

    if (ec_debug_init(&device->dbg, ifname)) {
        EC_ERR("Failed to init debug device!\n");
        goto out_return;
    }
#endif

    for (i = 0; i < EC_TX_RING_SIZE; i++)
        device->tx_skb[i] = NULL;

    for (i = 0; i < EC_TX_RING_SIZE; i++) {
        if (!(device->tx_skb[i] = dev_alloc_skb(ETH_FRAME_LEN))) {
            EC_ERR("Error allocating device socket buffer!\n");
            goto out_tx_ring;
        }

        // add Ethernet-II-header
        skb_reserve(device->tx_skb[i], ETH_HLEN);
        eth = (struct ethhdr *) skb_push(device->tx_skb[i], ETH_HLEN);
        eth->h_proto = htons(0x88A4);
        memset(eth->h_dest, 0xFF, ETH_ALEN);
    }

    ec_device_detach(device); // resets remaining fields
    return 0;

out_tx_ring:
    for (i = 0; i < EC_TX_RING_SIZE; i++)
        if (device->tx_skb[i])
            dev_kfree_skb(device->tx_skb[i]);
#ifdef EC_DEBUG_IF
    ec_debug_clear(&device->dbg);
out_return:
#endif
    return -1;
}

/*****************************************************************************/

/**
   EtherCAT device destuctor.
*/

void ec_device_clear(ec_device_t *device /**< EtherCAT device */)
{
    unsigned int i;

    if (device->open) ec_device_close(device);
    for (i = 0; i < EC_TX_RING_SIZE; i++)
        dev_kfree_skb(device->tx_skb[i]);
#ifdef EC_DEBUG_IF
    ec_debug_clear(&device->dbg);
#endif
}

/*****************************************************************************/

/**
   Associate with net_device.
*/

void ec_device_attach(ec_device_t *device, /**< EtherCAT device */
        struct net_device *net_dev, /**< net_device structure */
        ec_pollfunc_t poll, /**< pointer to device's poll function */
        struct module *module /**< the device's module */
        )
{
    unsigned int i;
    struct ethhdr *eth;

    ec_device_detach(device); // resets fields

    device->dev = net_dev;
    device->poll = poll;
    device->module = module;

    for (i = 0; i < EC_TX_RING_SIZE; i++) {
        device->tx_skb[i]->dev = net_dev;
        eth = (struct ethhdr *) (device->tx_skb[i]->data);
        memcpy(eth->h_source, net_dev->dev_addr, ETH_ALEN);
    }
}

/*****************************************************************************/

/**
   Disconnect from net_device.
*/

void ec_device_detach(ec_device_t *device /**< EtherCAT device */)
{
    unsigned int i;

    device->dev = NULL;
    device->poll = NULL;
    device->module = NULL;
    device->open = 0;
    device->link_state = 0; // down
    device->tx_count = 0;
    device->rx_count = 0;
    for (i = 0; i < EC_TX_RING_SIZE; i++)
        device->tx_skb[i]->dev = NULL;
}

/*****************************************************************************/

/**
   Opens the EtherCAT device.
   \return 0 in case of success, else < 0
*/

int ec_device_open(ec_device_t *device /**< EtherCAT device */)
{
    if (!device->dev) {
        EC_ERR("No net_device to open!\n");
        return -1;
    }

    if (device->open) {
        EC_WARN("Device already opened!\n");
        return 0;
    }

    device->link_state = 0;
    device->tx_count = 0;
    device->rx_count = 0;

    if (device->dev->open(device->dev) == 0) device->open = 1;

    return device->open ? 0 : -1;
}

/*****************************************************************************/

/**
   Stops the EtherCAT device.
   \return 0 in case of success, else < 0
*/

int ec_device_close(ec_device_t *device /**< EtherCAT device */)
{
    if (!device->dev) {
        EC_ERR("No device to close!\n");
        return -1;
    }

    if (!device->open) {
        EC_WARN("Device already closed!\n");
        return 0;
    }

    if (device->dev->stop(device->dev) == 0) device->open = 0;

    return !device->open ? 0 : -1;
}

/*****************************************************************************/

/**
   Returns a pointer to the device's transmit memory.
   \return pointer to the TX socket buffer
*/

uint8_t *ec_device_tx_data(ec_device_t *device /**< EtherCAT device */)
{
    /* cycle through socket buffers, because otherwise there is a race
     * condition, if multiple frames are sent and the DMA is not scheduled in
     * between. */
    device->tx_ring_index++;
    device->tx_ring_index %= EC_TX_RING_SIZE;
    return device->tx_skb[device->tx_ring_index]->data + ETH_HLEN;
}

/*****************************************************************************/

/**
   Sends the content of the transmit socket buffer.
   Cuts the socket buffer content to the (now known) size, and calls the
   start_xmit() function of the assigned net_device.
*/

void ec_device_send(ec_device_t *device, /**< EtherCAT device */
                    size_t size /**< number of bytes to send */
                    )
{
    struct sk_buff *skb = device->tx_skb[device->tx_ring_index];

    if (unlikely(!device->link_state)) // Link down
        return;

    // set the right length for the data
    skb->len = ETH_HLEN + size;

    if (unlikely(device->master->debug_level > 1)) {
        EC_DBG("sending frame:\n");
        ec_print_data(skb->data + ETH_HLEN, size);
    }

    // start sending
    if (device->dev->hard_start_xmit(skb, device->dev) == NETDEV_TX_OK) {
		device->tx_count++;
#ifdef EC_DEBUG_IF
		ec_debug_send(&device->dbg, skb->data, ETH_HLEN + size);
#endif
#ifdef EC_DEBUG_RING
		ec_device_debug_ring_append(
				device, TX, skb->data + ETH_HLEN, size);
#endif
	}
}

/*****************************************************************************/

#ifdef EC_DEBUG_RING
/**
 * Appends frame data to the debug ring.
 */

void ec_device_debug_ring_append(
        ec_device_t *device, /**< EtherCAT device */
        ec_debug_frame_dir_t dir, /**< direction */
        const void *data, /**< frame data */
        size_t size /**< data size */
        )
{
    ec_debug_frame_t *df = &device->debug_frames[device->debug_frame_index];

    df->dir = dir;
    if (dir == TX)
        do_gettimeofday(&df->t);
    else
        df->t = device->timeval_poll;
    memcpy(df->data, data, size);
    df->data_size = size;

    device->debug_frame_index++;
    device->debug_frame_index %= EC_DEBUG_RING_SIZE;
    if (unlikely(device->debug_frame_count < EC_DEBUG_RING_SIZE))
        device->debug_frame_count++;
}

/*****************************************************************************/

/**
 * Outputs the debug ring.
 */

void ec_device_debug_ring_print(
        const ec_device_t *device /**< EtherCAT device */
        )
{
    int i;
    unsigned int ring_index;
    const ec_debug_frame_t *df;
    struct timeval t0, diff;

    // calculate index of the newest frame in the ring to get its time
    ring_index = (device->debug_frame_index + EC_DEBUG_RING_SIZE - 1)
        % EC_DEBUG_RING_SIZE;
    t0 = device->debug_frames[ring_index].t;

    EC_DBG("Debug ring %u:\n", ring_index);

    // calculate index of the oldest frame in the ring
    ring_index = (device->debug_frame_index + EC_DEBUG_RING_SIZE
            - device->debug_frame_count) % EC_DEBUG_RING_SIZE;

    for (i = 0; i < device->debug_frame_count; i++) {
        df = &device->debug_frames[ring_index];
        timersub(&t0, &df->t, &diff);

        EC_DBG("Frame %u, dt=%u.%06u s, %s:\n",
                i + 1 - device->debug_frame_count,
                (unsigned int) diff.tv_sec,
                (unsigned int) diff.tv_usec,
                (df->dir == TX) ? "TX" : "RX");
        ec_print_data(df->data, df->data_size);

        ring_index++;
        ring_index %= EC_DEBUG_RING_SIZE;
    }
}
#endif

/*****************************************************************************/

/**
   Calls the poll function of the assigned net_device.
   The master itself works without using interrupts. Therefore the processing
   of received data and status changes of the network device has to be
   done by the master calling the ISR "manually".
*/

void ec_device_poll(ec_device_t *device /**< EtherCAT device */)
{
    device->cycles_poll = get_cycles();
    device->jiffies_poll = jiffies;
#ifdef EC_DEBUG_RING
    do_gettimeofday(&device->timeval_poll);
#endif
    device->poll(device->dev);
}

/******************************************************************************
 *  Device interface
 *****************************************************************************/

/**
   Accepts a received frame.
   Forwards the received data to the master. The master will analyze the frame
   and dispatch the received commands to the sending instances.
   \ingroup DeviceInterface
*/

void ecdev_receive(ec_device_t *device, /**< EtherCAT device */
                   const void *data, /**< pointer to received data */
                   size_t size /**< number of bytes received */
                   )
{
    const void *ec_data = data + ETH_HLEN;
    size_t ec_size = size - ETH_HLEN;
    device->rx_count++;

    if (unlikely(device->master->debug_level > 1)) {
        EC_DBG("Received frame:\n");
        ec_print_data(ec_data, ec_size);
    }

#ifdef EC_DEBUG_IF
    ec_debug_send(&device->dbg, data, size);
#endif
#ifdef EC_DEBUG_RING
    ec_device_debug_ring_append(device, RX, ec_data, ec_size);
#endif

    ec_master_receive_datagrams(device->master, ec_data, ec_size);
}

/*****************************************************************************/

/**
   Sets a new link state.
   If the device notifies the master about the link being down, the master
   will not try to send frames using this device.
   \ingroup DeviceInterface
*/

void ecdev_set_link(ec_device_t *device, /**< EtherCAT device */
        uint8_t state /**< new link state */
        )
{
    if (unlikely(!device)) {
        EC_WARN("ecdev_link_state: no device!\n");
        return;
    }

    if (likely(state != device->link_state)) {
        device->link_state = state;
        EC_INFO("Link state changed to %s.\n", (state ? "UP" : "DOWN"));
    }
}

/*****************************************************************************/

/**
   Reads the link state.
   \ingroup DeviceInterface
*/

uint8_t ecdev_get_link(ec_device_t *device /**< EtherCAT device */)
{
    if (unlikely(!device)) {
        EC_WARN("ecdev_link_state: no device!\n");
        return 0;
    }

    return device->link_state;
}

/*****************************************************************************/

/** \cond */

EXPORT_SYMBOL(ecdev_receive);
EXPORT_SYMBOL(ecdev_get_link);
EXPORT_SYMBOL(ecdev_set_link);

/** \endcond */

/*****************************************************************************/