master.c

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/******************************************************************************
 *
 *  $Id: master.c 533 2006-09-01 12:35:41Z fp $
 *
 *  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.
 *
 *****************************************************************************/

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

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/delay.h>

#include "../include/ecrt.h"
#include "globals.h"
#include "master.h"
#include "slave.h"
#include "device.h"
#include "datagram.h"
#include "ethernet.h"

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

void ec_master_sync_io(ec_master_t *);
void ec_master_idle_run(void *);
void ec_master_eoe_run(unsigned long);
ssize_t ec_show_master_attribute(struct kobject *, struct attribute *, char *);
ssize_t ec_store_master_attribute(struct kobject *, struct attribute *,
                                  const char *, size_t);

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

EC_SYSFS_READ_ATTR(info);
EC_SYSFS_READ_WRITE_ATTR(eeprom_write_enable);
EC_SYSFS_READ_WRITE_ATTR(debug_level);

static struct attribute *ec_def_attrs[] = {
    &attr_info,
    &attr_eeprom_write_enable,
    &attr_debug_level,
    NULL,
};

static struct sysfs_ops ec_sysfs_ops = {
    .show = &ec_show_master_attribute,
    .store = ec_store_master_attribute
};

static struct kobj_type ktype_ec_master = {
    .release = ec_master_clear,
    .sysfs_ops = &ec_sysfs_ops,
    .default_attrs = ec_def_attrs
};

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

int ec_master_init(ec_master_t *master, 
                   unsigned int index, 
                   unsigned int eoeif_count 
                   )
{
    ec_eoe_t *eoe, *next_eoe;
    unsigned int i;

    EC_INFO("Initializing master %i.\n", index);

    master->index = index;
    master->device = NULL;
    master->reserved = 0;
    INIT_LIST_HEAD(&master->slaves);
    INIT_LIST_HEAD(&master->datagram_queue);
    INIT_LIST_HEAD(&master->domains);
    INIT_LIST_HEAD(&master->eoe_handlers);
    INIT_WORK(&master->idle_work, ec_master_idle_run, (void *) master);
    init_timer(&master->eoe_timer);
    master->eoe_timer.function = ec_master_eoe_run;
    master->eoe_timer.data = (unsigned long) master;
    master->internal_lock = SPIN_LOCK_UNLOCKED;
    master->eoe_running = 0;
    master->eoe_checked = 0;
    for (i = 0; i < HZ; i++) {
        master->idle_cycle_times[i] = 0;
        master->eoe_cycle_times[i] = 0;
    }
    master->idle_cycle_time_pos = 0;
    master->eoe_cycle_time_pos = 0;

    // create workqueue
    if (!(master->workqueue = create_singlethread_workqueue("EtherCAT"))) {
        EC_ERR("Failed to create master workqueue.\n");
        goto out_return;
    }

    // create EoE handlers
    for (i = 0; i < eoeif_count; i++) {
        if (!(eoe = (ec_eoe_t *) kmalloc(sizeof(ec_eoe_t), GFP_KERNEL))) {
            EC_ERR("Failed to allocate EoE-Object.\n");
            goto out_clear_eoe;
        }
        if (ec_eoe_init(eoe)) {
            kfree(eoe);
            goto out_clear_eoe;
        }
        list_add_tail(&eoe->list, &master->eoe_handlers);
    }

    // create state machine object
    if (ec_fsm_init(&master->fsm, master)) goto out_clear_eoe;

    // init kobject and add it to the hierarchy
    memset(&master->kobj, 0x00, sizeof(struct kobject));
    kobject_init(&master->kobj);
    master->kobj.ktype = &ktype_ec_master;
    if (kobject_set_name(&master->kobj, "ethercat%i", index)) {
        EC_ERR("Failed to set kobj name.\n");
        kobject_put(&master->kobj);
        return -1;
    }

    ec_master_reset(master);
    return 0;

 out_clear_eoe:
    list_for_each_entry_safe(eoe, next_eoe, &master->eoe_handlers, list) {
        list_del(&eoe->list);
        ec_eoe_clear(eoe);
        kfree(eoe);
    }
    destroy_workqueue(master->workqueue);
 out_return:
    return -1;
}

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

void ec_master_clear(struct kobject *kobj )
{
    ec_master_t *master = container_of(kobj, ec_master_t, kobj);
    ec_eoe_t *eoe, *next_eoe;

    EC_INFO("Clearing master %i...\n", master->index);

    ec_master_reset(master);
    ec_fsm_clear(&master->fsm);
    destroy_workqueue(master->workqueue);

    // clear EoE objects
    list_for_each_entry_safe(eoe, next_eoe, &master->eoe_handlers, list) {
        list_del(&eoe->list);
        ec_eoe_clear(eoe);
        kfree(eoe);
    }

    if (master->device) {
        ec_device_clear(master->device);
        kfree(master->device);
    }

    EC_INFO("Master %i cleared.\n", master->index);
}

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

void ec_master_reset(ec_master_t *master )
{
    ec_datagram_t *datagram, *next_c;
    ec_domain_t *domain, *next_d;

    ec_master_eoe_stop(master);
    ec_master_idle_stop(master);
    ec_master_clear_slaves(master);

    // empty datagram queue
    list_for_each_entry_safe(datagram, next_c,
                             &master->datagram_queue, queue) {
        datagram->state = EC_DATAGRAM_ERROR;
        list_del_init(&datagram->queue);
    }

    // clear domains
    list_for_each_entry_safe(domain, next_d, &master->domains, list) {
        list_del(&domain->list);
        kobject_del(&domain->kobj);
        kobject_put(&domain->kobj);
    }

    master->datagram_index = 0;
    master->debug_level = 0;

    master->stats.timeouts = 0;
    master->stats.corrupted = 0;
    master->stats.skipped = 0;
    master->stats.unmatched = 0;
    master->stats.output_jiffies = 0;

    master->mode = EC_MASTER_MODE_ORPHANED;

    master->request_cb = NULL;
    master->release_cb = NULL;
    master->cb_data = NULL;

    master->eeprom_write_enable = 0;

    ec_fsm_reset(&master->fsm);
}

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

void ec_master_clear_slaves(ec_master_t *master)
{
    ec_slave_t *slave, *next_slave;

    list_for_each_entry_safe(slave, next_slave, &master->slaves, list) {
        list_del(&slave->list);
        kobject_del(&slave->kobj);
        kobject_put(&slave->kobj);
    }
    master->slave_count = 0;
}

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

void ec_master_queue_datagram(ec_master_t *master, 
                              ec_datagram_t *datagram 
                              )
{
    ec_datagram_t *queued_datagram;

    // check, if the datagram is already queued
    list_for_each_entry(queued_datagram, &master->datagram_queue, queue) {
        if (queued_datagram == datagram) {
            master->stats.skipped++;
            ec_master_output_stats(master);
            datagram->state = EC_DATAGRAM_QUEUED;
            return;
        }
    }

    list_add_tail(&datagram->queue, &master->datagram_queue);
    datagram->state = EC_DATAGRAM_QUEUED;
}

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

void ec_master_send_datagrams(ec_master_t *master )
{
    ec_datagram_t *datagram;
    size_t datagram_size;
    uint8_t *frame_data, *cur_data;
    void *follows_word;
    cycles_t cycles_start, cycles_end;
    unsigned int frame_count, more_datagrams_waiting;

    frame_count = 0;
    cycles_start = get_cycles();

    if (unlikely(master->debug_level > 1))
        EC_DBG("ec_master_send_datagrams\n");

    do {
        // fetch pointer to transmit socket buffer
        frame_data = ec_device_tx_data(master->device);
        cur_data = frame_data + EC_FRAME_HEADER_SIZE;
        follows_word = NULL;
        more_datagrams_waiting = 0;

        // fill current frame with datagrams
        list_for_each_entry(datagram, &master->datagram_queue, queue) {
            if (datagram->state != EC_DATAGRAM_QUEUED) continue;

            // does the current datagram fit in the frame?
            datagram_size = EC_DATAGRAM_HEADER_SIZE + datagram->data_size
                + EC_DATAGRAM_FOOTER_SIZE;
            if (cur_data - frame_data + datagram_size > ETH_DATA_LEN) {
                more_datagrams_waiting = 1;
                break;
            }

            datagram->state = EC_DATAGRAM_SENT;
            datagram->cycles_sent = cycles_start;
            datagram->index = master->datagram_index++;

            if (unlikely(master->debug_level > 1))
                EC_DBG("adding datagram 0x%02X\n", datagram->index);

            // set "datagram following" flag in previous frame
            if (follows_word)
                EC_WRITE_U16(follows_word, EC_READ_U16(follows_word) | 0x8000);

            // EtherCAT datagram header
            EC_WRITE_U8 (cur_data,     datagram->type);
            EC_WRITE_U8 (cur_data + 1, datagram->index);
            EC_WRITE_U32(cur_data + 2, datagram->address.logical);
            EC_WRITE_U16(cur_data + 6, datagram->data_size & 0x7FF);
            EC_WRITE_U16(cur_data + 8, 0x0000);
            follows_word = cur_data + 6;
            cur_data += EC_DATAGRAM_HEADER_SIZE;

            // EtherCAT datagram data
            memcpy(cur_data, datagram->data, datagram->data_size);
            cur_data += datagram->data_size;

            // EtherCAT datagram footer
            EC_WRITE_U16(cur_data, 0x0000); // reset working counter
            cur_data += EC_DATAGRAM_FOOTER_SIZE;
        }

        if (cur_data - frame_data == EC_FRAME_HEADER_SIZE) {
            if (unlikely(master->debug_level > 1))
                EC_DBG("nothing to send.\n");
            break;
        }

        // EtherCAT frame header
        EC_WRITE_U16(frame_data, ((cur_data - frame_data
                                   - EC_FRAME_HEADER_SIZE) & 0x7FF) | 0x1000);

        // pad frame
        while (cur_data - frame_data < ETH_ZLEN - ETH_HLEN)
            EC_WRITE_U8(cur_data++, 0x00);

        if (unlikely(master->debug_level > 1))
            EC_DBG("frame size: %i\n", cur_data - frame_data);

        // send frame
        ec_device_send(master->device, cur_data - frame_data);
        frame_count++;
    }
    while (more_datagrams_waiting);

    if (unlikely(master->debug_level > 1)) {
        cycles_end = get_cycles();
        EC_DBG("ec_master_send_datagrams sent %i frames in %ius.\n",
               frame_count,
               (unsigned int) (cycles_end - cycles_start) * 1000 / cpu_khz);
    }
}

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

void ec_master_receive_datagrams(ec_master_t *master, 
                                 const uint8_t *frame_data, 
                                 size_t size 
                                 )
{
    size_t frame_size, data_size;
    uint8_t datagram_type, datagram_index;
    unsigned int cmd_follows, matched;
    const uint8_t *cur_data;
    ec_datagram_t *datagram;

    if (unlikely(size < EC_FRAME_HEADER_SIZE)) {
        master->stats.corrupted++;
        ec_master_output_stats(master);
        return;
    }

    cur_data = frame_data;

    // check length of entire frame
    frame_size = EC_READ_U16(cur_data) & 0x07FF;
    cur_data += EC_FRAME_HEADER_SIZE;

    if (unlikely(frame_size > size)) {
        master->stats.corrupted++;
        ec_master_output_stats(master);
        return;
    }

    cmd_follows = 1;
    while (cmd_follows) {
        // process datagram header
        datagram_type  = EC_READ_U8 (cur_data);
        datagram_index = EC_READ_U8 (cur_data + 1);
        data_size      = EC_READ_U16(cur_data + 6) & 0x07FF;
        cmd_follows    = EC_READ_U16(cur_data + 6) & 0x8000;
        cur_data += EC_DATAGRAM_HEADER_SIZE;

        if (unlikely(cur_data - frame_data
                     + data_size + EC_DATAGRAM_FOOTER_SIZE > size)) {
            master->stats.corrupted++;
            ec_master_output_stats(master);
            return;
        }

        // search for matching datagram in the queue
        matched = 0;
        list_for_each_entry(datagram, &master->datagram_queue, queue) {
            if (datagram->state == EC_DATAGRAM_SENT
                && datagram->type == datagram_type
                && datagram->index == datagram_index
                && datagram->data_size == data_size) {
                matched = 1;
                break;
            }
        }

        // no matching datagram was found
        if (!matched) {
            master->stats.unmatched++;
            ec_master_output_stats(master);
            cur_data += data_size + EC_DATAGRAM_FOOTER_SIZE;
            continue;
        }

        // copy received data into the datagram memory
        memcpy(datagram->data, cur_data, data_size);
        cur_data += data_size;

        // set the datagram's working counter
        datagram->working_counter = EC_READ_U16(cur_data);
        cur_data += EC_DATAGRAM_FOOTER_SIZE;

        // dequeue the received datagram
        datagram->state = EC_DATAGRAM_RECEIVED;
        list_del_init(&datagram->queue);
    }
}

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

int ec_master_bus_scan(ec_master_t *master )
{
    ec_fsm_t *fsm = &master->fsm;

    ec_fsm_startup(fsm); // init startup state machine

    do {
        ec_fsm_execute(fsm);
        ec_master_sync_io(master);
    }
    while (ec_fsm_startup_running(fsm));

    if (!ec_fsm_startup_success(fsm)) {
        ec_master_clear_slaves(master);
        return -1;
    }

    return 0;
}

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

void ec_master_output_stats(ec_master_t *master )
{
    if (unlikely(jiffies - master->stats.output_jiffies >= HZ)) {
        master->stats.output_jiffies = jiffies;

        if (master->stats.timeouts) {
            EC_WARN("%i datagrams TIMED OUT!\n", master->stats.timeouts);
            master->stats.timeouts = 0;
        }
        if (master->stats.corrupted) {
            EC_WARN("%i frame(s) CORRUPTED!\n", master->stats.corrupted);
            master->stats.corrupted = 0;
        }
        if (master->stats.skipped) {
            EC_WARN("%i datagram(s) SKIPPED!\n", master->stats.skipped);
            master->stats.skipped = 0;
        }
        if (master->stats.unmatched) {
            EC_WARN("%i datagram(s) UNMATCHED!\n", master->stats.unmatched);
            master->stats.unmatched = 0;
        }
    }
}

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

void ec_master_idle_start(ec_master_t *master )
{
    if (master->mode == EC_MASTER_MODE_IDLE) return;

    if (master->mode == EC_MASTER_MODE_OPERATION) {
        EC_ERR("ec_master_idle_start: Master already running!\n");
        return;
    }

    EC_INFO("Starting Idle mode.\n");

    master->mode = EC_MASTER_MODE_IDLE;
    ec_fsm_reset(&master->fsm);
    queue_delayed_work(master->workqueue, &master->idle_work, 1);
}

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

void ec_master_idle_stop(ec_master_t *master )
{
    if (master->mode != EC_MASTER_MODE_IDLE) return;

    ec_master_eoe_stop(master);

    EC_INFO("Stopping Idle mode.\n");
    master->mode = EC_MASTER_MODE_ORPHANED; // this is important for the
                                            // IDLE work function to not
                                            // queue itself again

    if (!cancel_delayed_work(&master->idle_work)) {
        flush_workqueue(master->workqueue);
    }

    ec_master_clear_slaves(master);
}

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

void ec_master_idle_run(void *data )
{
    ec_master_t *master = (ec_master_t *) data;
    cycles_t cycles_start, cycles_end;

    // aquire master lock
    spin_lock_bh(&master->internal_lock);

    cycles_start = get_cycles();
    ecrt_master_receive(master);

    // execute master state machine
    ec_fsm_execute(&master->fsm);

    ecrt_master_send(master);
    cycles_end = get_cycles();

    // release master lock
    spin_unlock_bh(&master->internal_lock);

    master->idle_cycle_times[master->idle_cycle_time_pos]
        = (u32) (cycles_end - cycles_start) * 1000 / cpu_khz;
    master->idle_cycle_time_pos++;
    master->idle_cycle_time_pos %= HZ;

    if (master->mode == EC_MASTER_MODE_IDLE)
        queue_delayed_work(master->workqueue, &master->idle_work, 1);
}

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

void ec_sync_config(const ec_sii_sync_t *sync, 
                    const ec_slave_t *slave, 
                    uint8_t *data 
                    )
{
    size_t sync_size;

    sync_size = ec_slave_calc_sync_size(slave, sync);

    if (slave->master->debug_level) {
        EC_INFO("Slave %i, sync manager %i:\n", slave->ring_position,
                sync->index);
        EC_INFO("  Address: 0x%04X\n", sync->physical_start_address);
        EC_INFO("     Size: %i\n", sync_size);
        EC_INFO("  Control: 0x%02X\n", sync->control_register);
    }

    EC_WRITE_U16(data,     sync->physical_start_address);
    EC_WRITE_U16(data + 2, sync_size);
    EC_WRITE_U8 (data + 4, sync->control_register);
    EC_WRITE_U8 (data + 5, 0x00); // status byte (read only)
    EC_WRITE_U16(data + 6, sync->enable ? 0x0001 : 0x0000); // enable
}

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

void ec_fmmu_config(const ec_fmmu_t *fmmu, 
                    const ec_slave_t *slave, 
                    uint8_t *data 
                    )
{
    size_t sync_size;

    sync_size = ec_slave_calc_sync_size(slave, fmmu->sync);

    EC_WRITE_U32(data,      fmmu->logical_start_address);
    EC_WRITE_U16(data + 4,  sync_size); // size of fmmu
    EC_WRITE_U8 (data + 6,  0x00); // logical start bit
    EC_WRITE_U8 (data + 7,  0x07); // logical end bit
    EC_WRITE_U16(data + 8,  fmmu->sync->physical_start_address);
    EC_WRITE_U8 (data + 10, 0x00); // physical start bit
    EC_WRITE_U8 (data + 11, ((fmmu->sync->control_register & 0x04)
                             ? 0x02 : 0x01));
    EC_WRITE_U16(data + 12, 0x0001); // enable
    EC_WRITE_U16(data + 14, 0x0000); // reserved
}

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

ssize_t ec_master_info(ec_master_t *master, 
                       char *buffer 
                       )
{
    off_t off = 0;
    ec_eoe_t *eoe;
    uint32_t cur, sum, min, max, pos, i;

    off += sprintf(buffer + off, "\nMode: ");
    switch (master->mode) {
        case EC_MASTER_MODE_ORPHANED:
            off += sprintf(buffer + off, "ORPHANED");
            break;
        case EC_MASTER_MODE_IDLE:
            off += sprintf(buffer + off, "IDLE");
            break;
        case EC_MASTER_MODE_OPERATION:
            off += sprintf(buffer + off, "OPERATION");
            break;
    }

    off += sprintf(buffer + off, "\nSlaves: %i\n",
                   master->slave_count);

    off += sprintf(buffer + off, "\nTiming (min/avg/max) [us]:\n");

    sum = 0;
    min = 0xFFFFFFFF;
    max = 0;
    pos = master->idle_cycle_time_pos;
    for (i = 0; i < HZ; i++) {
        cur = master->idle_cycle_times[(i + pos) % HZ];
        sum += cur;
        if (cur < min) min = cur;
        if (cur > max) max = cur;
    }
    off += sprintf(buffer + off, "  Idle cycle: %u / %u.%u / %u\n",
                   min, sum / HZ, (sum * 100 / HZ) % 100, max);

    sum = 0;
    min = 0xFFFFFFFF;
    max = 0;
    pos = master->eoe_cycle_time_pos;
    for (i = 0; i < HZ; i++) {
        cur = master->eoe_cycle_times[(i + pos) % HZ];
        sum += cur;
        if (cur < min) min = cur;
        if (cur > max) max = cur;
    }
    off += sprintf(buffer + off, "  EoE cycle: %u / %u.%u / %u\n",
                   min, sum / HZ, (sum * 100 / HZ) % 100, max);

    if (!list_empty(&master->eoe_handlers))
        off += sprintf(buffer + off, "\nEoE statistics (RX/TX) [bps]:\n");
    list_for_each_entry(eoe, &master->eoe_handlers, list) {
        off += sprintf(buffer + off, "  %s: %u / %u (%u KB/s)\n",
                       eoe->dev->name, eoe->rx_rate, eoe->tx_rate,
                       ((eoe->rx_rate + eoe->tx_rate) / 8 + 512) / 1024);
    }

    off += sprintf(buffer + off, "\n");

    return off;
}

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

ssize_t ec_show_master_attribute(struct kobject *kobj, 
                                 struct attribute *attr, 
                                 char *buffer 
                                 )
{
    ec_master_t *master = container_of(kobj, ec_master_t, kobj);

    if (attr == &attr_info) {
        return ec_master_info(master, buffer);
    }
    else if (attr == &attr_debug_level) {
        return sprintf(buffer, "%i\n", master->debug_level);
    }
    else if (attr == &attr_eeprom_write_enable) {
        return sprintf(buffer, "%i\n", master->eeprom_write_enable);
    }

    return 0;
}

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

ssize_t ec_store_master_attribute(struct kobject *kobj, 
                                  struct attribute *attr, 
                                  const char *buffer, 
                                  size_t size 
                                  )
{
    ec_master_t *master = container_of(kobj, ec_master_t, kobj);

    if (attr == &attr_eeprom_write_enable) {
        if (!strcmp(buffer, "1\n")) {
            master->eeprom_write_enable = 1;
            EC_INFO("Slave EEPROM writing enabled.\n");
            return size;
        }
        else if (!strcmp(buffer, "0\n")) {
            master->eeprom_write_enable = 0;
            EC_INFO("Slave EEPROM writing disabled.\n");
            return size;
        }

        EC_ERR("Invalid value for eeprom_write_enable!\n");

        if (master->eeprom_write_enable) {
            master->eeprom_write_enable = 0;
            EC_INFO("Slave EEPROM writing disabled.\n");
        }
    }
    else if (attr == &attr_debug_level) {
        if (!strcmp(buffer, "0\n")) {
            master->debug_level = 0;
        }
        else if (!strcmp(buffer, "1\n")) {
            master->debug_level = 1;
        }
        else if (!strcmp(buffer, "2\n")) {
            master->debug_level = 2;
        }
        else {
            EC_ERR("Invalid debug level value!\n");
            return -EINVAL;
        }

        EC_INFO("Master debug level set to %i.\n", master->debug_level);
        return size;
    }

    return -EINVAL;
}

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

void ec_master_eoe_start(ec_master_t *master )
{
    ec_eoe_t *eoe;
    ec_slave_t *slave;
    unsigned int coupled, found;

    if (master->eoe_running || master->eoe_checked) return;

    master->eoe_checked = 1;

    // if the locking callbacks are not set in operation mode,
    // the EoE timer my not be started.
    if (master->mode == EC_MASTER_MODE_OPERATION
        && (!master->request_cb || !master->release_cb)) {
        EC_INFO("No EoE processing because of missing locking callbacks.\n");
        return;
    }

    // decouple all EoE handlers
    list_for_each_entry(eoe, &master->eoe_handlers, list)
        eoe->slave = NULL;

    // couple a free EoE handler to every EoE-capable slave
    coupled = 0;
    list_for_each_entry(slave, &master->slaves, list) {
        if (!(slave->sii_mailbox_protocols & EC_MBOX_EOE)) continue;

        found = 0;
        list_for_each_entry(eoe, &master->eoe_handlers, list) {
            if (eoe->slave) continue;
            eoe->slave = slave;
            found = 1;
            coupled++;
            EC_INFO("Coupling device %s to slave %i.\n",
                    eoe->dev->name, slave->ring_position);
            if (eoe->opened) slave->requested_state = EC_SLAVE_STATE_OP;
            else slave->requested_state = EC_SLAVE_STATE_INIT;
            slave->error_flag = 0;
            break;
        }

        if (!found) {
            EC_WARN("No EoE handler for slave %i!\n", slave->ring_position);
            slave->requested_state = EC_SLAVE_STATE_INIT;
            slave->error_flag = 0;
        }
    }

    if (!coupled) {
        EC_INFO("No EoE handlers coupled.\n");
        return;
    }

    EC_INFO("Starting EoE processing.\n");
    master->eoe_running = 1;

    // start EoE processing
    master->eoe_timer.expires = jiffies + 10;
    add_timer(&master->eoe_timer);
    return;
}

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

void ec_master_eoe_stop(ec_master_t *master )
{
    ec_eoe_t *eoe;

    master->eoe_checked = 0;

    if (!master->eoe_running) return;

    EC_INFO("Stopping EoE processing.\n");

    del_timer_sync(&master->eoe_timer);

    // decouple all EoE handlers
    list_for_each_entry(eoe, &master->eoe_handlers, list) {
        if (eoe->slave) {
            eoe->slave->requested_state = EC_SLAVE_STATE_INIT;
            eoe->slave->error_flag = 0;
            eoe->slave = NULL;
        }
    }

    master->eoe_running = 0;
}

/*****************************************************************************/
void ec_master_eoe_run(unsigned long data )
{
    ec_master_t *master = (ec_master_t *) data;
    ec_eoe_t *eoe;
    unsigned int active = 0;
    cycles_t cycles_start, cycles_end;
    unsigned long restart_jiffies;

    list_for_each_entry(eoe, &master->eoe_handlers, list) {
        if (ec_eoe_active(eoe)) active++;
    }
    if (!active) goto queue_timer;

    // aquire master lock...
    if (master->mode == EC_MASTER_MODE_OPERATION) {
        // request_cb must return 0, if the lock has been aquired!
        if (master->request_cb(master->cb_data))
            goto queue_timer;
    }
    else if (master->mode == EC_MASTER_MODE_IDLE) {
        spin_lock(&master->internal_lock);
    }
    else
        goto queue_timer;

    // actual EoE processing
    cycles_start = get_cycles();
    ecrt_master_receive(master);

    list_for_each_entry(eoe, &master->eoe_handlers, list) {
        ec_eoe_run(eoe);
    }

    ecrt_master_send(master);
    cycles_end = get_cycles();

    // release lock...
    if (master->mode == EC_MASTER_MODE_OPERATION) {
        master->release_cb(master->cb_data);
    }
    else if (master->mode == EC_MASTER_MODE_IDLE) {
        spin_unlock(&master->internal_lock);
    }

    master->eoe_cycle_times[master->eoe_cycle_time_pos]
        = (u32) (cycles_end - cycles_start) * 1000 / cpu_khz;
    master->eoe_cycle_time_pos++;
    master->eoe_cycle_time_pos %= HZ;

 queue_timer:
    restart_jiffies = HZ / EC_EOE_FREQUENCY;
    if (!restart_jiffies) restart_jiffies = 1;
    master->eoe_timer.expires += restart_jiffies;
    add_timer(&master->eoe_timer);
}

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

void ec_master_calc_addressing(ec_master_t *master )
{
    uint16_t coupler_index, coupler_subindex;
    uint16_t reverse_coupler_index, current_coupler_index;
    ec_slave_t *slave;

    coupler_index = 0;
    reverse_coupler_index = 0xFFFF;
    current_coupler_index = 0x0000;
    coupler_subindex = 0;

    list_for_each_entry(slave, &master->slaves, list) {
        if (ec_slave_is_coupler(slave)) {
            if (slave->sii_alias)
                current_coupler_index = reverse_coupler_index--;
            else
                current_coupler_index = coupler_index++;
            coupler_subindex = 0;
        }

        slave->coupler_index = current_coupler_index;
        slave->coupler_subindex = coupler_subindex;
        coupler_subindex++;
    }
}

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

void ec_master_measure_bus_time(ec_master_t *master)
{
    ec_datagram_t datagram;
    cycles_t cycles_start, cycles_end, cycles_timeout;
    uint32_t times[100], sum, min, max, i;

    ec_datagram_init(&datagram);

    if (ec_datagram_brd(&datagram, 0x130, 2)) {
        EC_ERR("Failed to allocate datagram for bus time measuring.\n");
        ec_datagram_clear(&datagram);
        return;
    }

    cycles_timeout = (cycles_t) EC_IO_TIMEOUT * (cpu_khz / 1000);

    sum = 0;
    min = 0xFFFFFFFF;
    max = 0;

    for (i = 0; i < 100; i++) {
        ec_master_queue_datagram(master, &datagram);
        ecrt_master_send(master);
        cycles_start = get_cycles();

        while (1) { // active waiting
            ec_device_call_isr(master->device);
            cycles_end = get_cycles(); // take current time

            if (datagram.state == EC_DATAGRAM_RECEIVED) {
                break;
            }
            else if (datagram.state == EC_DATAGRAM_ERROR) {
                EC_WARN("Failed to measure bus time.\n");
                goto error;
            }
            else if (cycles_end - cycles_start >= cycles_timeout) {
                EC_WARN("Timeout while measuring bus time.\n");
                goto error;
            }
        }

        times[i] = (unsigned int) (cycles_end - cycles_start) * 1000 / cpu_khz;
        sum += times[i];
        if (times[i] > max) max = times[i];
        if (times[i] < min) min = times[i];
    }

    EC_INFO("Bus time is (min/avg/max) %u/%u.%u/%u us.\n",
            min, sum / 100, sum % 100, max);

  error:
    // Dequeue and free datagram
    list_del(&datagram.queue);
    ec_datagram_clear(&datagram);
}

/******************************************************************************
 *  Realtime interface
 *****************************************************************************/

ec_domain_t *ecrt_master_create_domain(ec_master_t *master )
{
    ec_domain_t *domain, *last_domain;
    unsigned int index;

    if (!(domain = (ec_domain_t *) kmalloc(sizeof(ec_domain_t), GFP_KERNEL))) {
        EC_ERR("Error allocating domain memory!\n");
        goto out_return;
    }

    if (list_empty(&master->domains)) index = 0;
    else {
        last_domain = list_entry(master->domains.prev, ec_domain_t, list);
        index = last_domain->index + 1;
    }

    if (ec_domain_init(domain, master, index)) {
        EC_ERR("Failed to init domain.\n");
        goto out_return;
    }

    if (kobject_add(&domain->kobj)) {
        EC_ERR("Failed to add domain kobject.\n");
        goto out_put;
    }

    list_add_tail(&domain->list, &master->domains);
    return domain;

 out_put:
    kobject_put(&domain->kobj);
 out_return:
    return NULL;
}

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

int ecrt_master_activate(ec_master_t *master )
{
    uint32_t domain_offset;
    ec_domain_t *domain;
    ec_fsm_t *fsm = &master->fsm;
    ec_slave_t *slave;

    // allocate all domains
    domain_offset = 0;
    list_for_each_entry(domain, &master->domains, list) {
        if (ec_domain_alloc(domain, domain_offset)) {
            EC_ERR("Failed to allocate domain %X!\n", (u32) domain);
            return -1;
        }
        domain_offset += domain->data_size;
    }

    // determine initial states.
    list_for_each_entry(slave, &master->slaves, list) {
        if (ec_slave_is_coupler(slave) || slave->registered) {
            slave->requested_state = EC_SLAVE_STATE_OP;
        }
        else {
            slave->requested_state = EC_SLAVE_STATE_PREOP;
        }
    }

    ec_fsm_configuration(fsm); // init configuration state machine

    do {
        ec_fsm_execute(fsm);
        ec_master_sync_io(master);
    }
    while (ec_fsm_configuration_running(fsm));

    if (!ec_fsm_configuration_success(fsm)) {
        return -1;
    }

    ec_fsm_reset(&master->fsm); // prepare for operation state machine

    return 0;
}

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

void ecrt_master_deactivate(ec_master_t *master )
{
    ec_fsm_t *fsm = &master->fsm;
    ec_slave_t *slave;

    list_for_each_entry(slave, &master->slaves, list) {
        slave->requested_state = EC_SLAVE_STATE_INIT;
    }

    ec_fsm_configuration(fsm); // init configuration state machine

    do {
        ec_fsm_execute(fsm);
        ec_master_sync_io(master);
    }
    while (ec_fsm_configuration_running(fsm));
}

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

void ec_master_sync_io(ec_master_t *master )
{
    ec_datagram_t *datagram;
    unsigned int datagrams_waiting;

    // send datagrams
    ecrt_master_send(master);

    while (1) { // active waiting
        ecrt_master_receive(master); // receive and dequeue datagrams

        // count number of datagrams still waiting for response
        datagrams_waiting = 0;
        list_for_each_entry(datagram, &master->datagram_queue, queue) {
            datagrams_waiting++;
        }

        // if there are no more datagrams waiting, abort loop.
        if (!datagrams_waiting) break;
    }
}

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

void ecrt_master_send(ec_master_t *master )
{
    ec_datagram_t *datagram, *n;

    if (unlikely(!master->device->link_state)) {
        // link is down, no datagram can be sent
        list_for_each_entry_safe(datagram, n, &master->datagram_queue, queue) {
            datagram->state = EC_DATAGRAM_ERROR;
            list_del_init(&datagram->queue);
        }

        // query link state
        ec_device_call_isr(master->device);
        return;
    }

    // send frames
    ec_master_send_datagrams(master);
}

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

void ecrt_master_receive(ec_master_t *master )
{
    ec_datagram_t *datagram, *next;
    cycles_t cycles_received, cycles_timeout;

    ec_device_call_isr(master->device);

    cycles_received = get_cycles();
    cycles_timeout = EC_IO_TIMEOUT * cpu_khz / 1000;

    // dequeue all datagrams that timed out
    list_for_each_entry_safe(datagram, next, &master->datagram_queue, queue) {
        switch (datagram->state) {
            case EC_DATAGRAM_SENT:
            case EC_DATAGRAM_QUEUED:
                if (cycles_received - datagram->cycles_sent > cycles_timeout) {
                    list_del_init(&datagram->queue);
                    datagram->state = EC_DATAGRAM_TIMED_OUT;
                    master->stats.timeouts++;
                    ec_master_output_stats(master);
                }
                break;
            default:
                break;
        }
    }
}

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

void ecrt_master_prepare(ec_master_t *master )
{
    ec_domain_t *domain;
    cycles_t cycles_start, cycles_end, cycles_timeout;

    // queue datagrams of all domains
    list_for_each_entry(domain, &master->domains, list)
        ec_domain_queue(domain);

    ecrt_master_send(master);

    cycles_start = get_cycles(); // take sending time
    cycles_timeout = (cycles_t) EC_IO_TIMEOUT * (cpu_khz / 1000);

    // active waiting
    while (1) {
        cycles_end = get_cycles();
        if (cycles_end - cycles_start >= cycles_timeout) break;
    }
}

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

void ecrt_master_run(ec_master_t *master )
{
    // output statistics
    ec_master_output_stats(master);

    // execute master state machine
    ec_fsm_execute(&master->fsm);
}

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

ec_slave_t *ecrt_master_get_slave(const ec_master_t *master, 
                                  const char *address 
                                  )
{
    unsigned long first, second;
    char *remainder, *remainder2;
    unsigned int alias_requested, alias_found;
    ec_slave_t *alias_slave = NULL, *slave;

    if (!address || address[0] == 0) return NULL;

    alias_requested = 0;
    if (address[0] == '#') {
        alias_requested = 1;
        address++;
    }

    first = simple_strtoul(address, &remainder, 0);
    if (remainder == address) {
        EC_ERR("Slave address \"%s\" - First number empty!\n", address);
        return NULL;
    }

    if (alias_requested) {
        alias_found = 0;
        list_for_each_entry(alias_slave, &master->slaves, list) {
            if (alias_slave->sii_alias == first) {
                alias_found = 1;
                break;
            }
        }
        if (!alias_found) {
            EC_ERR("Slave address \"%s\" - Alias not found!\n", address);
            return NULL;
        }
    }

    if (!remainder[0]) { // absolute position
        if (alias_requested) {
            return alias_slave;
        }
        else {
            list_for_each_entry(slave, &master->slaves, list) {
                if (slave->ring_position == first) return slave;
            }
            EC_ERR("Slave address \"%s\" - Absolute position invalid!\n",
                   address);
        }
    }
    else if (remainder[0] == ':') { // field position
        remainder++;
        second = simple_strtoul(remainder, &remainder2, 0);

        if (remainder2 == remainder) {
            EC_ERR("Slave address \"%s\" - Second number empty!\n", address);
            return NULL;
        }

        if (remainder2[0]) {
            EC_ERR("Slave address \"%s\" - Invalid trailer!\n", address);
            return NULL;
        }

        if (alias_requested) {
            if (!ec_slave_is_coupler(alias_slave)) {
                EC_ERR("Slave address \"%s\": Alias slave must be bus coupler"
                       " in colon mode.\n", address);
                return NULL;
            }
            list_for_each_entry(slave, &master->slaves, list) {
                if (slave->coupler_index == alias_slave->coupler_index
                    && slave->coupler_subindex == second)
                    return slave;
            }
            EC_ERR("Slave address \"%s\" - Bus coupler %i has no %lu. slave"
                   " following!\n", address, alias_slave->ring_position,
                   second);
            return NULL;
        }
        else {
            list_for_each_entry(slave, &master->slaves, list) {
                if (slave->coupler_index == first
                    && slave->coupler_subindex == second) return slave;
            }
        }
    }
    else
        EC_ERR("Slave address \"%s\" - Invalid format!\n", address);

    return NULL;
}

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

void ecrt_master_callbacks(ec_master_t *master, 
                           int (*request_cb)(void *), 
                           void (*release_cb)(void *), 
                           void *cb_data 
                           )
{
    master->request_cb = request_cb;
    master->release_cb = release_cb;
    master->cb_data = cb_data;
}

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

EXPORT_SYMBOL(ecrt_master_create_domain);
EXPORT_SYMBOL(ecrt_master_activate);
EXPORT_SYMBOL(ecrt_master_deactivate);
EXPORT_SYMBOL(ecrt_master_prepare);
EXPORT_SYMBOL(ecrt_master_send);
EXPORT_SYMBOL(ecrt_master_receive);
EXPORT_SYMBOL(ecrt_master_run);
EXPORT_SYMBOL(ecrt_master_callbacks);
EXPORT_SYMBOL(ecrt_master_get_slave);

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

---