/******************************************************************************
 *
 *  d e v i c e . c
 *
 *  EtherCAT device methods.
 *
 *  $Id$
 *
 *****************************************************************************/

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

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

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

/**
   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 */
                   struct net_device *net_dev, /**< net_device structure */
                   ec_isr_t isr, /**< pointer to device's ISR */
                   struct module *module /**< pointer to the owning module */
                   )
{
    struct ethhdr *eth;

    device->master = master;
    device->dev = net_dev;
    device->isr = isr;
    device->module = module;

    device->open = 0;
    device->link_state = 0; // down

    if (!(device->tx_skb = dev_alloc_skb(ETH_HLEN + EC_MAX_FRAME_SIZE))) {
        EC_ERR("Error allocating device socket buffer!\n");
        return -1;
    }

    device->tx_skb->dev = net_dev;

    // add Ethernet-II-header
    skb_reserve(device->tx_skb, ETH_HLEN);
    eth = (struct ethhdr *) skb_push(device->tx_skb, ETH_HLEN);
    eth->h_proto = htons(0x88A4);
    memcpy(eth->h_source, net_dev->dev_addr, net_dev->addr_len);
    memset(eth->h_dest, 0xFF, net_dev->addr_len);

    return 0;
}

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

/**
   EtherCAT device destuctor.
*/

void ec_device_clear(ec_device_t *device /**< EtherCAT device */)
{
    if (device->open) ec_device_close(device);
    if (device->tx_skb) dev_kfree_skb(device->tx_skb);
}

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

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

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

    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 could have received frames before
    for (i = 0; i < 4; i++) ec_device_call_isr(device);

    device->link_state = 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 */)
{
    return device->tx_skb->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 */
                    )
{
    if (unlikely(!device->link_state)) // Link down
        return;

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

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

    // start sending
    device->dev->hard_start_xmit(device->tx_skb, device->dev);
}

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

/**
   Calls the interrupt service routine of the assigned net_device.
*/

void ec_device_call_isr(ec_device_t *device /**< EtherCAT device */)
{
    if (likely(device->isr)) device->isr(0, device->dev, NULL);
}

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

/**
   Accepts a received frame.
   Forwards the received data to the master.
*/

void ecdev_receive(ec_device_t *device, /**< EtherCAT device */
                   const void *data, /**< pointer to receibed data */
                   size_t size /**< number of bytes received */
                   )
{
    if (unlikely(device->master->debug_level > 1)) {
        EC_DBG("Received frame:\n");
        ec_print_data_diff(device->tx_skb->data + ETH_HLEN, data, size);
    }

    ec_master_receive(device->master, data, size);
}

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

/**
   Sets a new link state.
*/

void ecdev_link_state(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"));
    }
}

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

EXPORT_SYMBOL(ecdev_receive);
EXPORT_SYMBOL(ecdev_link_state);

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