master/fsm.c
branchstable-1.0
changeset 1619 0d4119024f55
child 1621 4bbe090553f7
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/master/fsm.c	Mon May 29 09:08:56 2006 +0000
@@ -0,0 +1,1758 @@
+/******************************************************************************
+ *
+ *  $Id$
+ *
+ *  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 finite state machines.
+*/
+
+/*****************************************************************************/
+
+#include "globals.h"
+#include "fsm.h"
+#include "master.h"
+
+/*****************************************************************************/
+
+/**
+   Size of memory to allocate while reading categories.
+*/
+
+#define EC_CAT_MEM 0x100
+
+/*****************************************************************************/
+
+const ec_code_msg_t al_status_messages[];
+
+/*****************************************************************************/
+
+void ec_fsm_master_start(ec_fsm_t *);
+void ec_fsm_master_broadcast(ec_fsm_t *);
+void ec_fsm_master_proc_states(ec_fsm_t *);
+void ec_fsm_master_scan(ec_fsm_t *);
+void ec_fsm_master_states(ec_fsm_t *);
+void ec_fsm_master_validate_vendor(ec_fsm_t *);
+void ec_fsm_master_validate_product(ec_fsm_t *);
+void ec_fsm_master_reconfigure(ec_fsm_t *);
+void ec_fsm_master_address(ec_fsm_t *);
+void ec_fsm_master_conf(ec_fsm_t *);
+
+void ec_fsm_slave_start_reading(ec_fsm_t *);
+void ec_fsm_slave_read_status(ec_fsm_t *);
+void ec_fsm_slave_read_base(ec_fsm_t *);
+void ec_fsm_slave_read_dl(ec_fsm_t *);
+void ec_fsm_slave_prepare_sii(ec_fsm_t *);
+void ec_fsm_slave_read_sii(ec_fsm_t *);
+void ec_fsm_slave_category_header(ec_fsm_t *);
+void ec_fsm_slave_category_data(ec_fsm_t *);
+void ec_fsm_slave_end(ec_fsm_t *);
+
+void ec_fsm_slave_conf(ec_fsm_t *);
+void ec_fsm_slave_sync(ec_fsm_t *);
+void ec_fsm_slave_preop(ec_fsm_t *);
+void ec_fsm_slave_fmmu(ec_fsm_t *);
+void ec_fsm_slave_saveop(ec_fsm_t *);
+void ec_fsm_slave_op(ec_fsm_t *);
+void ec_fsm_slave_op2(ec_fsm_t *);
+
+void ec_fsm_sii_start_reading(ec_fsm_t *);
+void ec_fsm_sii_check(ec_fsm_t *);
+void ec_fsm_sii_fetch(ec_fsm_t *);
+void ec_fsm_sii_end(ec_fsm_t *);
+void ec_fsm_sii_error(ec_fsm_t *);
+
+void ec_fsm_change_start(ec_fsm_t *);
+void ec_fsm_change_check(ec_fsm_t *);
+void ec_fsm_change_status(ec_fsm_t *);
+void ec_fsm_change_code(ec_fsm_t *);
+void ec_fsm_change_ack(ec_fsm_t *);
+void ec_fsm_change_ack2(ec_fsm_t *);
+void ec_fsm_change_end(ec_fsm_t *);
+void ec_fsm_change_error(ec_fsm_t *);
+
+/*****************************************************************************/
+
+/**
+   Constructor.
+*/
+
+int ec_fsm_init(ec_fsm_t *fsm, /**< finite state machine */
+                ec_master_t *master /**< EtherCAT master */
+                )
+{
+    fsm->master = master;
+    fsm->master_state = ec_fsm_master_start;
+    fsm->master_slaves_responding = 0;
+    fsm->master_slave_states = EC_SLAVE_STATE_UNKNOWN;
+    fsm->master_validation = 0;
+    fsm->slave_cat_data = NULL;
+
+    ec_command_init(&fsm->command);
+    if (ec_command_prealloc(&fsm->command, EC_MAX_DATA_SIZE)) {
+        EC_ERR("FSM failed to allocate FSM command.\n");
+        return -1;
+    }
+
+    return 0;
+}
+
+/*****************************************************************************/
+
+/**
+   Destructor.
+*/
+
+void ec_fsm_clear(ec_fsm_t *fsm /**< finite state machine */)
+{
+    if (fsm->slave_cat_data) kfree(fsm->slave_cat_data);
+    ec_command_clear(&fsm->command);
+}
+
+/*****************************************************************************/
+
+/**
+   Resets the state machine.
+*/
+
+void ec_fsm_reset(ec_fsm_t *fsm /**< finite state machine */)
+{
+    fsm->master_state = ec_fsm_master_start;
+    fsm->master_slaves_responding = 0;
+    fsm->master_slave_states = EC_SLAVE_STATE_UNKNOWN;
+
+    if (fsm->slave_cat_data) {
+        kfree(fsm->slave_cat_data);
+        fsm->slave_cat_data = NULL;
+    }
+}
+
+/*****************************************************************************/
+
+/**
+   Executes the current state of the state machine.
+*/
+
+void ec_fsm_execute(ec_fsm_t *fsm /**< finite state machine */)
+{
+    fsm->master_state(fsm);
+}
+
+/******************************************************************************
+ *  master state machine
+ *****************************************************************************/
+
+/**
+   Master state: START.
+   Starts with getting slave count and slave states.
+*/
+
+void ec_fsm_master_start(ec_fsm_t *fsm)
+{
+    ec_command_brd(&fsm->command, 0x0130, 2);
+    ec_master_queue_command(fsm->master, &fsm->command);
+    fsm->master_state = ec_fsm_master_broadcast;
+}
+
+/*****************************************************************************/
+
+/**
+   Master state: BROADCAST.
+   Processes the broadcast read slave count and slaves states.
+*/
+
+void ec_fsm_master_broadcast(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+    unsigned int topology_change, states_change, i;
+    ec_slave_t *slave;
+    ec_master_t *master = fsm->master;
+
+    if (command->state != EC_CMD_RECEIVED) {
+        if (!master->device->link_state) {
+            fsm->master_slaves_responding = 0;
+            list_for_each_entry(slave, &master->slaves, list) {
+                slave->online = 0;
+            }
+        }
+        fsm->master_state = ec_fsm_master_start;
+        fsm->master_state(fsm); // execute immediately
+        return;
+    }
+
+    topology_change = (command->working_counter !=
+                       fsm->master_slaves_responding);
+    states_change = (EC_READ_U8(command->data) != fsm->master_slave_states);
+
+    fsm->master_slave_states = EC_READ_U8(command->data);
+    fsm->master_slaves_responding = command->working_counter;
+
+    if (topology_change) {
+        EC_INFO("%i slave%s responding.\n",
+                fsm->master_slaves_responding,
+                fsm->master_slaves_responding == 1 ? "" : "s");
+
+        if (master->mode == EC_MASTER_MODE_RUNNING) {
+            if (fsm->master_slaves_responding == master->slave_count) {
+                fsm->master_validation = 1; // start validation later
+            }
+            else {
+                EC_WARN("Invalid slave count. Bus in tainted state.\n");
+            }
+        }
+    }
+
+    if (states_change) {
+        EC_INFO("Slave states: ");
+        ec_print_states(fsm->master_slave_states);
+        printk(".\n");
+    }
+
+    // topology change in free-run mode: clear all slaves and scan the bus
+    if (topology_change && master->mode == EC_MASTER_MODE_FREERUN) {
+        EC_INFO("Scanning bus.\n");
+
+        ec_master_eoe_stop(master);
+        ec_master_clear_slaves(master);
+
+        if (!fsm->master_slaves_responding) {
+            // no slaves present -> finish state machine.
+            fsm->master_state = ec_fsm_master_start;
+            fsm->master_state(fsm); // execute immediately
+            return;
+        }
+
+        // init slaves
+        for (i = 0; i < fsm->master_slaves_responding; i++) {
+            if (!(slave = (ec_slave_t *) kmalloc(sizeof(ec_slave_t),
+                                                 GFP_ATOMIC))) {
+                EC_ERR("Failed to allocate slave %i!\n", i);
+                fsm->master_state = ec_fsm_master_start;
+                fsm->master_state(fsm); // execute immediately
+                return;
+            }
+
+            if (ec_slave_init(slave, master, i, i + 1)) {
+                fsm->master_state = ec_fsm_master_start;
+                fsm->master_state(fsm); // execute immediately
+                return;
+            }
+
+            if (kobject_add(&slave->kobj)) {
+                EC_ERR("Failed to add kobject.\n");
+                kobject_put(&slave->kobj); // free
+                fsm->master_state = ec_fsm_master_start;
+                fsm->master_state(fsm); // execute immediately
+                return;
+            }
+
+            list_add_tail(&slave->list, &master->slaves);
+        }
+
+        // begin scanning of slaves
+        fsm->slave = list_entry(master->slaves.next, ec_slave_t, list);
+        fsm->slave_state = ec_fsm_slave_start_reading;
+        fsm->master_state = ec_fsm_master_scan;
+        fsm->master_state(fsm); // execute immediately
+        return;
+    }
+
+    // fetch state from each slave
+    fsm->slave = list_entry(master->slaves.next, ec_slave_t, list);
+    ec_command_nprd(&fsm->command, fsm->slave->station_address, 0x0130, 2);
+    ec_master_queue_command(master, &fsm->command);
+    fsm->master_state = ec_fsm_master_states;
+}
+
+/*****************************************************************************/
+
+/**
+   Master action: Get state of next slave.
+*/
+
+void ec_fsm_master_action_next_slave_state(ec_fsm_t *fsm
+                                           /**< finite state machine */)
+{
+    ec_master_t *master = fsm->master;
+    ec_slave_t *slave = fsm->slave;
+
+    // have all states been read?
+    if (slave->list.next == &master->slaves) {
+
+        // check, if a bus validation has to be done
+        if (fsm->master_validation) {
+            fsm->master_validation = 0;
+            list_for_each_entry(slave, &master->slaves, list) {
+                if (slave->online) continue;
+
+                // At least one slave is offline. validate!
+                EC_INFO("Validating bus.\n");
+                fsm->slave = list_entry(master->slaves.next, ec_slave_t, list);
+                fsm->master_state = ec_fsm_master_validate_vendor;
+                fsm->sii_offset = 0x0008; // vendor ID
+                fsm->sii_mode = 0;
+                fsm->sii_state = ec_fsm_sii_start_reading;
+                fsm->sii_state(fsm); // execute immediately
+                return;
+            }
+        }
+
+        fsm->master_state = ec_fsm_master_proc_states;
+        fsm->master_state(fsm); // execute immediately
+        return;
+    }
+
+    // process next slave
+    fsm->slave = list_entry(fsm->slave->list.next, ec_slave_t, list);
+    ec_command_nprd(&fsm->command, fsm->slave->station_address, 0x0130, 2);
+    ec_master_queue_command(master, &fsm->command);
+    fsm->master_state = ec_fsm_master_states;
+}
+
+/*****************************************************************************/
+
+/**
+   Master state: STATES.
+   Fetches the AL- and online state of a slave.
+*/
+
+void ec_fsm_master_states(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_slave_t *slave = fsm->slave;
+    ec_command_t *command = &fsm->command;
+    uint8_t new_state;
+
+    if (command->state != EC_CMD_RECEIVED) {
+        fsm->master_state = ec_fsm_master_start;
+        fsm->master_state(fsm); // execute immediately
+        return;
+    }
+
+    // did the slave not respond to its station address?
+    if (command->working_counter != 1) {
+        if (slave->online) {
+            slave->online = 0;
+            EC_INFO("Slave %i: offline.\n", slave->ring_position);
+        }
+        ec_fsm_master_action_next_slave_state(fsm);
+        return;
+    }
+
+    // slave responded
+    new_state = EC_READ_U8(command->data);
+    if (!slave->online) { // slave was offline before
+        slave->online = 1;
+        slave->state_error = 0;
+        slave->current_state = new_state;
+        EC_INFO("Slave %i: online (", slave->ring_position);
+        ec_print_states(new_state);
+        printk(").\n");
+    }
+    else if (new_state != slave->current_state) {
+        EC_INFO("Slave %i: ", slave->ring_position);
+        ec_print_states(slave->current_state);
+        printk(" -> ");
+        ec_print_states(new_state);
+        printk(".\n");
+        slave->current_state = new_state;
+    }
+
+    ec_fsm_master_action_next_slave_state(fsm);
+}
+
+/*****************************************************************************/
+
+/**
+   Master state: PROC_STATES.
+   Processes the slave states.
+*/
+
+void ec_fsm_master_proc_states(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_master_t *master = fsm->master;
+    ec_slave_t *slave;
+
+    // check if any slaves are not in the state, they're supposed to be
+    list_for_each_entry(slave, &master->slaves, list) {
+        if (slave->state_error || !slave->online ||
+            slave->requested_state == EC_SLAVE_STATE_UNKNOWN ||
+            slave->current_state == slave->requested_state) continue;
+
+        EC_INFO("Changing state of slave %i from ", slave->ring_position);
+        ec_print_states(slave->current_state);
+        printk(" to ");
+        ec_print_states(slave->requested_state);
+        printk(".\n");
+
+        fsm->slave = slave;
+        fsm->slave_state = ec_fsm_slave_conf;
+        fsm->change_new = EC_SLAVE_STATE_INIT;
+        fsm->change_state = ec_fsm_change_start;
+        fsm->master_state = ec_fsm_master_conf;
+        fsm->master_state(fsm); // execute immediately
+        return;
+    }
+
+    // nothing to configure. restart master state machine.
+    fsm->master_state = ec_fsm_master_start;
+    fsm->master_state(fsm); // execute immediately
+}
+
+/*****************************************************************************/
+
+/**
+   Master state: VALIDATE_VENDOR.
+   Validates the vendor ID of a slave.
+*/
+
+void ec_fsm_master_validate_vendor(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_slave_t *slave = fsm->slave;
+
+    fsm->sii_state(fsm); // execute SII state machine
+
+    if (fsm->sii_state == ec_fsm_sii_error) {
+        EC_ERR("Failed to validate vendor ID of slave %i.\n",
+               slave->ring_position);
+        fsm->master_state = ec_fsm_master_start;
+        fsm->master_state(fsm); // execute immediately
+        return;
+    }
+
+    if (fsm->sii_state != ec_fsm_sii_end) return;
+
+    if (fsm->sii_result != slave->sii_vendor_id) {
+        EC_ERR("Slave %i: invalid vendor ID!\n", slave->ring_position);
+        fsm->master_state = ec_fsm_master_start;
+        fsm->master_state(fsm); // execute immediately
+        return;
+    }
+
+    // vendor ID is ok. check product code.
+    fsm->master_state = ec_fsm_master_validate_product;
+    fsm->sii_offset = 0x000A; // product code
+    fsm->sii_mode = 0;
+    fsm->sii_state = ec_fsm_sii_start_reading;
+    fsm->sii_state(fsm); // execute immediately
+}
+
+/*****************************************************************************/
+
+/**
+   Master state: VALIDATE_PRODUCT.
+   Validates the product ID of a slave.
+*/
+
+void ec_fsm_master_validate_product(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_slave_t *slave = fsm->slave;
+
+    fsm->sii_state(fsm); // execute SII state machine
+
+    if (fsm->sii_state == ec_fsm_sii_error) {
+        EC_ERR("Failed to validate product code of slave %i.\n",
+               slave->ring_position);
+        fsm->master_state = ec_fsm_master_start;
+        fsm->master_state(fsm); // execute immediately
+        return;
+    }
+
+    if (fsm->sii_state != ec_fsm_sii_end) return;
+
+    if (fsm->sii_result != slave->sii_product_code) {
+        EC_ERR("Slave %i: invalid product code!\n", slave->ring_position);
+        EC_ERR("expected 0x%08X, got 0x%08X.\n", slave->sii_product_code,
+               fsm->sii_result);
+        fsm->master_state = ec_fsm_master_start;
+        fsm->master_state(fsm); // execute immediately
+        return;
+    }
+
+    // have all states been validated?
+    if (slave->list.next == &fsm->master->slaves) {
+        fsm->slave = list_entry(fsm->master->slaves.next, ec_slave_t, list);
+        fsm->master_state = ec_fsm_master_reconfigure;
+        return;
+    }
+
+    // validate next slave
+    fsm->slave = list_entry(fsm->slave->list.next, ec_slave_t, list);
+    fsm->master_state = ec_fsm_master_validate_vendor;
+    fsm->sii_offset = 0x0008; // vendor ID
+    fsm->sii_mode = 0;
+    fsm->sii_state = ec_fsm_sii_start_reading;
+    fsm->sii_state(fsm); // execute immediately
+}
+
+/*****************************************************************************/
+
+/**
+   Master state: RECONFIGURE.
+   Looks for slave, that have lost their configuration and writes
+   their station address, so that they can be reconfigured later.
+*/
+
+void ec_fsm_master_reconfigure(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+
+    while (fsm->slave->online) {
+        if (fsm->slave->list.next == &fsm->master->slaves) { // last slave?
+            fsm->master_state = ec_fsm_master_start;
+            fsm->master_state(fsm); // execute immediately
+            return;
+        }
+        // check next slave
+        fsm->slave = list_entry(fsm->slave->list.next, ec_slave_t, list);
+    }
+
+    EC_INFO("Reinitializing slave %i.\n", fsm->slave->ring_position);
+
+    // write station address
+    ec_command_apwr(command, fsm->slave->ring_position, 0x0010, 2);
+    EC_WRITE_U16(command->data, fsm->slave->station_address);
+    ec_master_queue_command(fsm->master, command);
+    fsm->master_state = ec_fsm_master_address;
+}
+
+/*****************************************************************************/
+
+/**
+   Master state: ADDRESS.
+   Checks, if the new station address has been written to the slave.
+*/
+
+void ec_fsm_master_address(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_slave_t *slave = fsm->slave;
+    ec_command_t *command = &fsm->command;
+
+    if (command->state != EC_CMD_RECEIVED || command->working_counter != 1) {
+        EC_ERR("Failed to write station address on slave %i.\n",
+               slave->ring_position);
+    }
+
+    if (fsm->slave->list.next == &fsm->master->slaves) { // last slave?
+        fsm->master_state = ec_fsm_master_start;
+        fsm->master_state(fsm); // execute immediately
+        return;
+    }
+
+    // check next slave
+    fsm->slave = list_entry(fsm->slave->list.next, ec_slave_t, list);
+    fsm->master_state = ec_fsm_master_reconfigure;
+    fsm->master_state(fsm); // execute immediately
+}
+
+/*****************************************************************************/
+
+/**
+   Master state: SCAN.
+   Executes the sub-statemachine for the scanning of a slave.
+*/
+
+void ec_fsm_master_scan(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_master_t *master = fsm->master;
+    ec_slave_t *slave = fsm->slave;
+    uint16_t coupler_index, coupler_subindex;
+    uint16_t reverse_coupler_index, current_coupler_index;
+    ec_slave_ident_t *ident;
+
+    fsm->slave_state(fsm); // execute slave state machine
+
+    if (fsm->slave_state != ec_fsm_slave_end) return;
+
+    // have all slaves been fetched?
+    if (slave->list.next == &master->slaves) {
+        EC_INFO("Bus scanning completed.\n");
+
+        // identify all slaves and calculate coupler addressing
+
+        coupler_index = 0;
+        reverse_coupler_index = 0xFFFF;
+        current_coupler_index = 0x3FFF;
+        coupler_subindex = 0;
+
+        list_for_each_entry(slave, &master->slaves, list)
+        {
+            // search for identification in "database"
+            ident = slave_idents;
+            while (ident->type) {
+                if (ident->vendor_id == slave->sii_vendor_id
+                    && ident->product_code == slave->sii_product_code) {
+                    slave->type = ident->type;
+                    break;
+                }
+                ident++;
+            }
+
+            if (!slave->type) {
+                EC_WARN("FSM: Unknown slave device (vendor 0x%08X,"
+                        " code 0x%08X) at position %i.\n",
+                        slave->sii_vendor_id, slave->sii_product_code,
+                        slave->ring_position);
+            }
+            else {
+                // if the slave is a bus coupler, change adressing base
+                if (slave->type->special == EC_TYPE_BUS_COUPLER) {
+                    if (slave->sii_alias)
+                        current_coupler_index = reverse_coupler_index--;
+                    else
+                        current_coupler_index = coupler_index++;
+                    coupler_subindex = 0;
+                }
+            }
+
+            // determine initial state.
+            if ((slave->type && slave->type->special == EC_TYPE_BUS_COUPLER)) {
+                slave->requested_state = EC_SLAVE_STATE_OP;
+            }
+            else {
+                if (master->mode == EC_MASTER_MODE_RUNNING)
+                    slave->requested_state = EC_SLAVE_STATE_PREOP;
+                else
+                    slave->requested_state = EC_SLAVE_STATE_INIT;
+            }
+            slave->state_error = 0;
+
+            // calculate coupler-based slave address
+            slave->coupler_index = current_coupler_index;
+            slave->coupler_subindex = coupler_subindex;
+            coupler_subindex++;
+        }
+
+        if (master->mode == EC_MASTER_MODE_FREERUN) {
+            // start EoE processing
+            ec_master_eoe_start(master);
+        }
+
+        fsm->master_state = ec_fsm_master_start;
+        fsm->master_state(fsm); // execute immediately
+        return;
+    }
+
+    // process next slave
+    fsm->slave = list_entry(fsm->slave->list.next, ec_slave_t, list);
+    fsm->slave_state = ec_fsm_slave_start_reading;
+    fsm->slave_state(fsm); // execute immediately
+}
+
+/*****************************************************************************/
+
+/**
+   Master state: CONF.
+   Starts configuring a slave.
+*/
+
+void ec_fsm_master_conf(ec_fsm_t *fsm /**< finite state machine */)
+{
+    fsm->slave_state(fsm); // execute slave's state machine
+    if (fsm->slave_state != ec_fsm_slave_end) return;
+    fsm->master_state = ec_fsm_master_proc_states;
+    fsm->master_state(fsm); // execute immediately
+}
+
+/******************************************************************************
+ *  slave state machine
+ *****************************************************************************/
+
+/**
+   Slave state: START_READING.
+   First state of the slave state machine. Writes the station address to the
+   slave, according to its ring position.
+*/
+
+void ec_fsm_slave_start_reading(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+
+    // write station address
+    ec_command_apwr(command, fsm->slave->ring_position, 0x0010, 2);
+    EC_WRITE_U16(command->data, fsm->slave->station_address);
+    ec_master_queue_command(fsm->master, command);
+    fsm->slave_state = ec_fsm_slave_read_status;
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: READ_STATUS.
+*/
+
+void ec_fsm_slave_read_status(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+
+    if (command->state != EC_CMD_RECEIVED || command->working_counter != 1) {
+        EC_ERR("FSM failed to write station address of slave %i.\n",
+               fsm->slave->ring_position);
+        fsm->slave_state = ec_fsm_slave_end;
+        return;
+    }
+
+    // read AL status
+    ec_command_nprd(command, fsm->slave->station_address, 0x0130, 2);
+    ec_master_queue_command(fsm->master, command);
+    fsm->slave_state = ec_fsm_slave_read_base;
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: READ_BASE.
+*/
+
+void ec_fsm_slave_read_base(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+    ec_slave_t *slave = fsm->slave;
+
+    if (command->state != EC_CMD_RECEIVED || command->working_counter != 1) {
+        EC_ERR("FSM failed to read AL status of slave %i.\n",
+               fsm->slave->ring_position);
+        fsm->slave_state = ec_fsm_slave_end;
+        return;
+    }
+
+    slave->current_state = EC_READ_U8(command->data);
+    if (slave->current_state & EC_ACK) {
+        EC_WARN("Slave %i has status error bit set (0x%02X)!\n",
+                slave->ring_position, slave->current_state);
+        slave->current_state &= 0x0F;
+    }
+
+    // read base data
+    ec_command_nprd(command, fsm->slave->station_address, 0x0000, 6);
+    ec_master_queue_command(fsm->master, command);
+    fsm->slave_state = ec_fsm_slave_read_dl;
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: READ_DL.
+*/
+
+void ec_fsm_slave_read_dl(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+    ec_slave_t *slave = fsm->slave;
+
+    if (command->state != EC_CMD_RECEIVED || command->working_counter != 1) {
+        EC_ERR("FSM failed to read base data of slave %i.\n",
+               slave->ring_position);
+        fsm->slave_state = ec_fsm_slave_end;
+        return;
+    }
+
+    slave->base_type       = EC_READ_U8 (command->data);
+    slave->base_revision   = EC_READ_U8 (command->data + 1);
+    slave->base_build      = EC_READ_U16(command->data + 2);
+    slave->base_fmmu_count = EC_READ_U8 (command->data + 4);
+    slave->base_sync_count = EC_READ_U8 (command->data + 5);
+
+    if (slave->base_fmmu_count > EC_MAX_FMMUS)
+        slave->base_fmmu_count = EC_MAX_FMMUS;
+
+    // read data link status
+    ec_command_nprd(command, slave->station_address, 0x0110, 2);
+    ec_master_queue_command(slave->master, command);
+    fsm->slave_state = ec_fsm_slave_prepare_sii;
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: PREPARE_SII.
+*/
+
+void ec_fsm_slave_prepare_sii(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+    ec_slave_t *slave = fsm->slave;
+    uint16_t dl_status;
+    unsigned int i;
+
+    if (command->state != EC_CMD_RECEIVED || command->working_counter != 1) {
+        EC_ERR("FSM failed to read DL status of slave %i.\n",
+               slave->ring_position);
+        fsm->slave_state = ec_fsm_slave_end;
+        return;
+    }
+
+    dl_status = EC_READ_U16(command->data);
+
+    for (i = 0; i < 4; i++) {
+        slave->dl_link[i] = dl_status & (1 << (4 + i)) ? 1 : 0;
+        slave->dl_loop[i] = dl_status & (1 << (8 + i * 2)) ? 1 : 0;
+        slave->dl_signal[i] = dl_status & (1 << (9 + i * 2)) ? 1 : 0;
+    }
+
+    fsm->sii_offset = 0x0004;
+    fsm->sii_mode = 1;
+    fsm->sii_state = ec_fsm_sii_start_reading;
+    fsm->slave_sii_num = 0;
+    fsm->slave_state = ec_fsm_slave_read_sii;
+    fsm->slave_state(fsm); // execute state immediately
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: READ_SII.
+*/
+
+void ec_fsm_slave_read_sii(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_slave_t *slave = fsm->slave;
+
+    // execute SII state machine
+    fsm->sii_state(fsm);
+
+    if (fsm->sii_state == ec_fsm_sii_error) {
+        fsm->slave_state = ec_fsm_slave_end;
+        EC_ERR("FSM failed to read SII data at 0x%04X on slave %i.\n",
+               fsm->sii_offset, slave->ring_position);
+        return;
+    }
+
+    if (fsm->sii_state != ec_fsm_sii_end) return;
+
+    switch (fsm->slave_sii_num) {
+        case 0:
+            slave->sii_alias = fsm->sii_result & 0xFFFF;
+            fsm->sii_offset = 0x0008;
+            break;
+        case 1:
+            slave->sii_vendor_id = fsm->sii_result;
+            fsm->sii_offset = 0x000A;
+            break;
+        case 2:
+            slave->sii_product_code = fsm->sii_result;
+            fsm->sii_offset = 0x000C;
+            break;
+        case 3:
+            slave->sii_revision_number = fsm->sii_result;
+            fsm->sii_offset = 0x000E;
+            break;
+        case 4:
+            slave->sii_serial_number = fsm->sii_result;
+            fsm->sii_offset = 0x0018;
+            break;
+        case 5:
+            slave->sii_rx_mailbox_offset = fsm->sii_result & 0xFFFF;
+            slave->sii_rx_mailbox_size = fsm->sii_result >> 16;
+            fsm->sii_offset = 0x001A;
+            break;
+        case 6:
+            slave->sii_tx_mailbox_offset = fsm->sii_result & 0xFFFF;
+            slave->sii_tx_mailbox_size = fsm->sii_result >> 16;
+            fsm->sii_offset = 0x001C;
+            break;
+        case 7:
+            slave->sii_mailbox_protocols = fsm->sii_result & 0xFFFF;
+
+            fsm->slave_cat_offset = 0x0040;
+
+            if (fsm->slave_cat_data) {
+                EC_INFO("FSM freeing old category data on slave %i...\n",
+                        fsm->slave->ring_position);
+                kfree(fsm->slave_cat_data);
+            }
+
+            if (!(fsm->slave_cat_data =
+                  (uint8_t *) kmalloc(EC_CAT_MEM, GFP_ATOMIC))) {
+                EC_ERR("FSM Failed to allocate category data.\n");
+                fsm->slave_state = ec_fsm_slave_end;
+                return;
+            }
+
+            // start reading first category header
+            fsm->sii_offset = fsm->slave_cat_offset;
+            fsm->sii_state = ec_fsm_sii_start_reading;
+
+            fsm->slave_state = ec_fsm_slave_category_header;
+            fsm->slave_state(fsm); // execute state immediately
+            return;
+    }
+
+    fsm->slave_sii_num++;
+    fsm->sii_state = ec_fsm_sii_start_reading;
+    fsm->slave_state(fsm); // execute state immediately
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: CATEGORY_HEADER.
+   Start reading categories.
+*/
+
+void ec_fsm_slave_category_header(ec_fsm_t *fsm /**< finite state machine */)
+{
+    // execute SII state machine
+    fsm->sii_state(fsm);
+
+    if (fsm->sii_state == ec_fsm_sii_error) {
+        kfree(fsm->slave_cat_data);
+        fsm->slave_cat_data = NULL;
+        fsm->slave_state = ec_fsm_slave_end;
+        EC_ERR("FSM failed to read category header at 0x%04X on slave %i.\n",
+               fsm->slave_cat_offset, fsm->slave->ring_position);
+        return;
+    }
+
+    if (fsm->sii_state != ec_fsm_sii_end) return;
+
+    // last category?
+    if ((fsm->sii_result & 0xFFFF) == 0xFFFF) {
+        kfree(fsm->slave_cat_data);
+        fsm->slave_cat_data = NULL;
+        fsm->slave_state = ec_fsm_slave_end;
+        return;
+    }
+
+    fsm->slave_cat_type = fsm->sii_result & 0x7FFF;
+    fsm->slave_cat_words = (fsm->sii_result >> 16) & 0xFFFF;
+
+    if (fsm->slave_cat_words > EC_CAT_MEM * 2) {
+        EC_ERR("FSM category memory too small! %i words needed.\n",
+               fsm->slave_cat_words);
+        fsm->slave_state = ec_fsm_slave_end;
+        return;
+    }
+
+    // start reading category data
+    fsm->slave_cat_data_offset = 0;
+    fsm->sii_offset = (fsm->slave_cat_offset + 2 +
+                       fsm->slave_cat_data_offset);
+    fsm->sii_mode = 1;
+    fsm->sii_state = ec_fsm_sii_start_reading;
+    fsm->slave_state = ec_fsm_slave_category_data;
+    fsm->slave_state(fsm); // execute state immediately
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: CATEGORY_DATA.
+   Reads category data.
+*/
+
+void ec_fsm_slave_category_data(ec_fsm_t *fsm /**< finite state machine */)
+{
+    // execute SII state machine
+    fsm->sii_state(fsm);
+
+    if (fsm->sii_state == ec_fsm_sii_error) {
+        kfree(fsm->slave_cat_data);
+        fsm->slave_cat_data = NULL;
+        fsm->slave_state = ec_fsm_slave_end;
+        EC_ERR("FSM failed to read category 0x%02X data at 0x%04X"
+               " on slave %i.\n", fsm->slave_cat_type, fsm->sii_offset,
+               fsm->slave->ring_position);
+        return;
+    }
+
+    if (fsm->sii_state != ec_fsm_sii_end) return;
+
+    fsm->slave_cat_data[fsm->slave_cat_data_offset * 2] =
+        fsm->sii_result & 0xFF;
+    fsm->slave_cat_data[fsm->slave_cat_data_offset * 2 + 1] =
+        (fsm->sii_result >> 8) & 0xFF;
+
+    // read second word "on the fly"
+    if (fsm->slave_cat_data_offset + 1 < fsm->slave_cat_words) {
+        fsm->slave_cat_data_offset++;
+        fsm->slave_cat_data[fsm->slave_cat_data_offset * 2] =
+            (fsm->sii_result >> 16) & 0xFF;
+        fsm->slave_cat_data[fsm->slave_cat_data_offset * 2 + 1] =
+            (fsm->sii_result >> 24) & 0xFF;
+    }
+
+    fsm->slave_cat_data_offset++;
+
+    if (fsm->slave_cat_data_offset < fsm->slave_cat_words) {
+        fsm->sii_offset = (fsm->slave_cat_offset + 2 +
+                           fsm->slave_cat_data_offset);
+        fsm->sii_mode = 1;
+        fsm->sii_state = ec_fsm_sii_start_reading;
+        fsm->slave_state = ec_fsm_slave_category_data;
+        fsm->slave_state(fsm); // execute state immediately
+        return;
+    }
+
+    // category data complete
+    switch (fsm->slave_cat_type)
+    {
+        case 0x000A:
+            if (ec_slave_fetch_strings(fsm->slave, fsm->slave_cat_data))
+                goto out_free;
+            break;
+        case 0x001E:
+            if (ec_slave_fetch_general(fsm->slave, fsm->slave_cat_data))
+                goto out_free;
+            break;
+        case 0x0028:
+            break;
+        case 0x0029:
+            if (ec_slave_fetch_sync(fsm->slave, fsm->slave_cat_data,
+                                    fsm->slave_cat_words))
+                goto out_free;
+            break;
+        case 0x0032:
+            if (ec_slave_fetch_pdo(fsm->slave, fsm->slave_cat_data,
+                                   fsm->slave_cat_words,
+                                   EC_TX_PDO))
+                goto out_free;
+            break;
+        case 0x0033:
+            if (ec_slave_fetch_pdo(fsm->slave, fsm->slave_cat_data,
+                                   fsm->slave_cat_words,
+                                   EC_RX_PDO))
+                goto out_free;
+            break;
+        default:
+            EC_WARN("FSM: Unknown category type 0x%04X in slave %i.\n",
+                    fsm->slave_cat_type, fsm->slave->ring_position);
+    }
+
+    // start reading next category header
+    fsm->slave_cat_offset += 2 + fsm->slave_cat_words;
+    fsm->sii_offset = fsm->slave_cat_offset;
+    fsm->sii_mode = 1;
+    fsm->sii_state = ec_fsm_sii_start_reading;
+    fsm->slave_state = ec_fsm_slave_category_header;
+    fsm->slave_state(fsm); // execute state immediately
+    return;
+
+ out_free:
+    kfree(fsm->slave_cat_data);
+    fsm->slave_cat_data = NULL;
+    fsm->slave_state = ec_fsm_slave_end;
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: CONF.
+*/
+
+void ec_fsm_slave_conf(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_slave_t *slave = fsm->slave;
+    ec_master_t *master = fsm->master;
+    ec_command_t *command = &fsm->command;
+
+    fsm->change_state(fsm); // execute state change state machine
+
+    if (fsm->change_state == ec_fsm_change_error) {
+        fsm->slave_state = ec_fsm_slave_end;
+        return;
+    }
+
+    if (fsm->change_state != ec_fsm_change_end) return;
+
+    // slave is now in INIT
+    if (slave->current_state == slave->requested_state) {
+        fsm->slave_state = ec_fsm_slave_end;
+        return;
+    }
+
+    // check for slave registration
+    if (!slave->type) {
+        EC_WARN("Slave %i has unknown type!\n", slave->ring_position);
+    }
+
+    // check and reset CRC fault counters
+    //ec_slave_check_crc(slave);
+
+    if (!slave->base_fmmu_count) { // no fmmus
+        fsm->slave_state = ec_fsm_slave_sync;
+        fsm->slave_state(fsm); // execute immediately
+        return;
+    }
+
+    // reset FMMUs
+    ec_command_npwr(command, slave->station_address, 0x0600,
+                    EC_FMMU_SIZE * slave->base_fmmu_count);
+    memset(command->data, 0x00, EC_FMMU_SIZE * slave->base_fmmu_count);
+    ec_master_queue_command(master, command);
+    fsm->slave_state = ec_fsm_slave_sync;
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: SYNC.
+   Configure sync managers.
+*/
+
+void ec_fsm_slave_sync(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+    ec_slave_t *slave = fsm->slave;
+    unsigned int j;
+    const ec_sync_t *sync;
+    ec_eeprom_sync_t *eeprom_sync, mbox_sync;
+
+    if (command->state != EC_CMD_RECEIVED || command->working_counter != 1) {
+        EC_ERR("Failed to reset FMMUs of slave %i.\n",
+               slave->ring_position);
+        slave->state_error = 1;
+        fsm->slave_state = ec_fsm_slave_end;
+        return;
+    }
+
+    if (!slave->base_sync_count) { // no sync managers
+        fsm->slave_state = ec_fsm_slave_preop;
+        fsm->slave_state(fsm); // execute immediately
+        return;
+    }
+
+    // configure sync managers
+    ec_command_npwr(command, slave->station_address, 0x0800,
+                    EC_SYNC_SIZE * slave->base_sync_count);
+    memset(command->data, 0x00, EC_SYNC_SIZE * slave->base_sync_count);
+
+    // known slave type, take type's SM information
+    if (slave->type) {
+        for (j = 0; slave->type->sync_managers[j] && j < EC_MAX_SYNC; j++) {
+            sync = slave->type->sync_managers[j];
+            ec_sync_config(sync, command->data + EC_SYNC_SIZE * j);
+        }
+    }
+
+    // unknown type, but slave has mailbox
+    else if (slave->sii_mailbox_protocols)
+    {
+        // does it supply sync manager configurations in its EEPROM?
+        if (!list_empty(&slave->eeprom_syncs)) {
+            list_for_each_entry(eeprom_sync, &slave->eeprom_syncs, list) {
+                if (eeprom_sync->index >= slave->base_sync_count) {
+                    EC_ERR("Invalid sync manager configuration found!");
+                    fsm->slave_state = ec_fsm_slave_end;
+                    return;
+                }
+                ec_eeprom_sync_config(eeprom_sync,
+                                      command->data + EC_SYNC_SIZE
+                                      * eeprom_sync->index);
+            }
+        }
+
+        // no sync manager information; guess mailbox settings
+        else {
+            mbox_sync.physical_start_address =
+                slave->sii_rx_mailbox_offset;
+            mbox_sync.length = slave->sii_rx_mailbox_size;
+            mbox_sync.control_register = 0x26;
+            mbox_sync.enable = 1;
+            ec_eeprom_sync_config(&mbox_sync, command->data);
+
+            mbox_sync.physical_start_address =
+                slave->sii_tx_mailbox_offset;
+            mbox_sync.length = slave->sii_tx_mailbox_size;
+            mbox_sync.control_register = 0x22;
+            mbox_sync.enable = 1;
+            ec_eeprom_sync_config(&mbox_sync,
+                                  command->data + EC_SYNC_SIZE);
+        }
+
+        EC_INFO("Mailbox configured for unknown slave %i\n",
+                slave->ring_position);
+    }
+
+    ec_master_queue_command(fsm->master, command);
+    fsm->slave_state = ec_fsm_slave_preop;
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: PREOP.
+   Change slave state to PREOP.
+*/
+
+void ec_fsm_slave_preop(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+    ec_slave_t *slave = fsm->slave;
+
+    if (command->state != EC_CMD_RECEIVED || command->working_counter != 1) {
+        EC_ERR("Failed to set sync managers on slave %i.\n",
+               slave->ring_position);
+        slave->state_error = 1;
+        fsm->slave_state = ec_fsm_slave_end;
+        return;
+    }
+
+    fsm->change_new = EC_SLAVE_STATE_PREOP;
+    fsm->change_state = ec_fsm_change_start;
+    fsm->slave_state = ec_fsm_slave_fmmu;
+    fsm->change_state(fsm); // execute immediately
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: FMMU.
+   Configure FMMUs.
+*/
+
+void ec_fsm_slave_fmmu(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_slave_t *slave = fsm->slave;
+    ec_master_t *master = fsm->master;
+    ec_command_t *command = &fsm->command;
+    unsigned int j;
+
+    fsm->change_state(fsm); // execute state change state machine
+
+    if (fsm->change_state == ec_fsm_change_error) {
+        fsm->slave_state = ec_fsm_slave_end;
+        return;
+    }
+
+    if (fsm->change_state != ec_fsm_change_end) return;
+
+    // slave is now in PREOP
+    if (slave->current_state == slave->requested_state) {
+        fsm->slave_state = ec_fsm_slave_end;
+        return;
+    }
+
+    // stop activation here for slaves without type
+    if (!slave->type) {
+        fsm->slave_state = ec_fsm_slave_end;
+        return;
+    }
+
+    if (!slave->base_fmmu_count) {
+        fsm->slave_state = ec_fsm_slave_saveop;
+        fsm->slave_state(fsm); // execute immediately
+        return;
+    }
+
+    // configure FMMUs
+    ec_command_npwr(command, slave->station_address,
+                    0x0600, EC_FMMU_SIZE * slave->base_fmmu_count);
+    memset(command->data, 0x00, EC_FMMU_SIZE * slave->base_fmmu_count);
+    for (j = 0; j < slave->fmmu_count; j++) {
+        ec_fmmu_config(&slave->fmmus[j], command->data + EC_FMMU_SIZE * j);
+    }
+
+    ec_master_queue_command(master, command);
+    fsm->slave_state = ec_fsm_slave_saveop;
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: SAVEOP.
+   Set slave state to SAVEOP.
+*/
+
+void ec_fsm_slave_saveop(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+
+    if (fsm->slave->base_fmmu_count && (command->state != EC_CMD_RECEIVED ||
+                                        command->working_counter != 1)) {
+        EC_ERR("FSM failed to set FMMUs on slave %i.\n",
+               fsm->slave->ring_position);
+        fsm->slave->state_error = 1;
+        fsm->slave_state = ec_fsm_slave_end;
+        return;
+    }
+
+    // set state to SAVEOP
+    fsm->slave_state = ec_fsm_slave_op;
+    fsm->change_new = EC_SLAVE_STATE_SAVEOP;
+    fsm->change_state = ec_fsm_change_start;
+    fsm->change_state(fsm); // execute immediately
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: OP.
+   Set slave state to OP.
+*/
+
+void ec_fsm_slave_op(ec_fsm_t *fsm /**< finite state machine */)
+{
+    fsm->change_state(fsm); // execute state change state machine
+
+    if (fsm->change_state == ec_fsm_change_error) {
+        fsm->slave_state = ec_fsm_slave_end;
+        return;
+    }
+
+    if (fsm->change_state != ec_fsm_change_end) return;
+
+    // slave is now in SAVEOP
+    if (fsm->slave->current_state == fsm->slave->requested_state) {
+        fsm->slave_state = ec_fsm_slave_end;
+        return;
+    }
+
+    // set state to OP
+    fsm->slave_state = ec_fsm_slave_op2;
+    fsm->change_new = EC_SLAVE_STATE_OP;
+    fsm->change_state = ec_fsm_change_start;
+    fsm->change_state(fsm); // execute immediately
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: OP2
+   Executes the change state machine, until the OP state is set.
+*/
+
+void ec_fsm_slave_op2(ec_fsm_t *fsm /**< finite state machine */)
+{
+    fsm->change_state(fsm); // execute state change state machine
+
+    if (fsm->change_state == ec_fsm_change_error) {
+        fsm->slave_state = ec_fsm_slave_end;
+        return;
+    }
+
+    if (fsm->change_state != ec_fsm_change_end) return;
+
+    // slave is now in OP
+    fsm->slave_state = ec_fsm_slave_end;
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: END.
+   End state of the slave state machine.
+*/
+
+void ec_fsm_slave_end(ec_fsm_t *fsm /**< finite state machine */)
+{
+}
+
+/******************************************************************************
+ *  SII state machine
+ *****************************************************************************/
+
+/**
+   SII state: START_READING.
+   Starts reading the slave information interface.
+*/
+
+void ec_fsm_sii_start_reading(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+
+    // initiate read operation
+    if (fsm->sii_mode) {
+        ec_command_npwr(command, fsm->slave->station_address, 0x502, 4);
+    }
+    else {
+        ec_command_apwr(command, fsm->slave->ring_position, 0x502, 4);
+    }
+
+    EC_WRITE_U8 (command->data,     0x00); // read-only access
+    EC_WRITE_U8 (command->data + 1, 0x01); // request read operation
+    EC_WRITE_U16(command->data + 2, fsm->sii_offset);
+    ec_master_queue_command(fsm->master, command);
+    fsm->sii_state = ec_fsm_sii_check;
+}
+
+/*****************************************************************************/
+
+/**
+   SII state: CHECK.
+   Checks, if the SII-read-command has been sent and issues a fetch command.
+*/
+
+void ec_fsm_sii_check(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+
+    if (command->state != EC_CMD_RECEIVED || command->working_counter != 1) {
+        EC_ERR("SII: Reception of read command failed.\n");
+        fsm->sii_state = ec_fsm_sii_error;
+        return;
+    }
+
+    fsm->sii_start = get_cycles();
+
+    // issue check/fetch command
+    if (fsm->sii_mode) {
+        ec_command_nprd(command, fsm->slave->station_address, 0x502, 10);
+    }
+    else {
+        ec_command_aprd(command, fsm->slave->ring_position, 0x502, 10);
+    }
+
+    ec_master_queue_command(fsm->master, command);
+    fsm->sii_state = ec_fsm_sii_fetch;
+}
+
+/*****************************************************************************/
+
+/**
+   SII state: FETCH.
+   Fetches the result of an SII-read command.
+*/
+
+void ec_fsm_sii_fetch(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+
+    if (command->state != EC_CMD_RECEIVED || command->working_counter != 1) {
+        EC_ERR("SII: Reception of check/fetch command failed.\n");
+        fsm->sii_state = ec_fsm_sii_error;
+        return;
+    }
+
+    // check "busy bit"
+    if (EC_READ_U8(command->data + 1) & 0x81) {
+        // still busy... timeout?
+        if (get_cycles() - fsm->sii_start >= (cycles_t) 10 * cpu_khz) {
+            EC_ERR("SII: Timeout.\n");
+            fsm->sii_state = ec_fsm_sii_error;
+#if 0
+            EC_DBG("SII busy: %02X %02X %02X %02X\n",
+                   EC_READ_U8(command->data + 0),
+                   EC_READ_U8(command->data + 1),
+                   EC_READ_U8(command->data + 2),
+                   EC_READ_U8(command->data + 3));
+#endif
+        }
+
+        // issue check/fetch command again
+        if (fsm->sii_mode) {
+            ec_command_nprd(command, fsm->slave->station_address, 0x502, 10);
+        }
+        else {
+            ec_command_aprd(command, fsm->slave->ring_position, 0x502, 10);
+        }
+        ec_master_queue_command(fsm->master, command);
+        return;
+    }
+
+#if 0
+    EC_DBG("SII rec: %02X %02X %02X %02X - %02X %02X %02X %02X\n",
+           EC_READ_U8(command->data + 0), EC_READ_U8(command->data + 1),
+           EC_READ_U8(command->data + 2), EC_READ_U8(command->data + 3),
+           EC_READ_U8(command->data + 6), EC_READ_U8(command->data + 7),
+           EC_READ_U8(command->data + 8), EC_READ_U8(command->data + 9));
+#endif
+
+    // SII value received.
+    fsm->sii_result = EC_READ_U32(command->data + 6);
+    fsm->sii_state = ec_fsm_sii_end;
+}
+
+/*****************************************************************************/
+
+/**
+   SII state: END.
+   End state of the slave SII state machine.
+*/
+
+void ec_fsm_sii_end(ec_fsm_t *fsm /**< finite state machine */)
+{
+}
+
+/*****************************************************************************/
+
+/**
+   SII state: ERROR.
+   End state of the slave SII state machine.
+*/
+
+void ec_fsm_sii_error(ec_fsm_t *fsm /**< finite state machine */)
+{
+}
+
+/******************************************************************************
+ *  state change state machine
+ *****************************************************************************/
+
+/**
+   Change state: START.
+*/
+
+void ec_fsm_change_start(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+    ec_slave_t *slave = fsm->slave;
+
+    // write new state to slave
+    ec_command_npwr(command, slave->station_address, 0x0120, 2);
+    EC_WRITE_U16(command->data, fsm->change_new);
+    ec_master_queue_command(fsm->master, command);
+    fsm->change_state = ec_fsm_change_check;
+}
+
+/*****************************************************************************/
+
+/**
+   Change state: CHECK.
+*/
+
+void ec_fsm_change_check(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+    ec_slave_t *slave = fsm->slave;
+
+    if (command->state != EC_CMD_RECEIVED) {
+        EC_ERR("Failed to send state command to slave %i!\n",
+               fsm->slave->ring_position);
+        slave->state_error = 1;
+        fsm->change_state = ec_fsm_change_error;
+        return;
+    }
+
+    if (command->working_counter != 1) {
+        EC_ERR("Failed to set state 0x%02X on slave %i: Slave did not"
+               " respond.\n", fsm->change_new, fsm->slave->ring_position);
+        slave->state_error = 1;
+        fsm->change_state = ec_fsm_change_error;
+        return;
+    }
+
+    fsm->change_start = get_cycles();
+
+    // read AL status from slave
+    ec_command_nprd(command, slave->station_address, 0x0130, 2);
+    ec_master_queue_command(fsm->master, command);
+    fsm->change_state = ec_fsm_change_status;
+}
+
+/*****************************************************************************/
+
+/**
+   Change state: STATUS.
+*/
+
+void ec_fsm_change_status(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+    ec_slave_t *slave = fsm->slave;
+
+    if (command->state != EC_CMD_RECEIVED || command->working_counter != 1) {
+        EC_ERR("Failed to check state 0x%02X on slave %i.\n",
+               fsm->change_new, slave->ring_position);
+        slave->state_error = 1;
+        fsm->change_state = ec_fsm_change_error;
+        return;
+    }
+
+    slave->current_state = EC_READ_U8(command->data);
+
+    if (slave->current_state == fsm->change_new) {
+        // state has been set successfully
+        fsm->change_state = ec_fsm_change_end;
+        return;
+    }
+
+    if (slave->current_state & 0x10) {
+        // state change error
+        fsm->change_new = slave->current_state & 0x0F;
+        EC_ERR("Failed to set state 0x%02X - Slave %i refused state change"
+               " (code 0x%02X)!\n", fsm->change_new, slave->ring_position,
+               slave->current_state);
+        // fetch AL status error code
+        ec_command_nprd(command, slave->station_address, 0x0134, 2);
+        ec_master_queue_command(fsm->master, command);
+        fsm->change_state = ec_fsm_change_code;
+        return;
+    }
+
+    if (get_cycles() - fsm->change_start >= (cycles_t) 10 * cpu_khz) {
+        // timeout while checking
+        slave->state_error = 1;
+        fsm->change_state = ec_fsm_change_error;
+        EC_ERR("Timeout while setting state 0x%02X on slave %i.\n",
+               fsm->change_new, slave->ring_position);
+        return;
+    }
+
+    // still old state: check again
+    ec_command_nprd(command, slave->station_address, 0x0130, 2);
+    ec_master_queue_command(fsm->master, command);
+}
+
+/*****************************************************************************/
+
+/**
+   Change state: CODE.
+*/
+
+void ec_fsm_change_code(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+    ec_slave_t *slave = fsm->slave;
+    uint32_t code;
+    const ec_code_msg_t *al_msg;
+
+    if (command->state != EC_CMD_RECEIVED || command->working_counter != 1) {
+        EC_ERR("Reception of AL status code command failed.\n");
+        slave->state_error = 1;
+        fsm->change_state = ec_fsm_change_error;
+        return;
+    }
+
+    if ((code = EC_READ_U16(command->data))) {
+        for (al_msg = al_status_messages; al_msg->code; al_msg++) {
+            if (al_msg->code != code) continue;
+            EC_ERR("AL status message 0x%04X: \"%s\".\n",
+                   al_msg->code, al_msg->message);
+            break;
+        }
+        if (!al_msg->code)
+            EC_ERR("Unknown AL status code 0x%04X.\n", code);
+    }
+
+    // acknowledge "old" slave state
+    ec_command_npwr(command, slave->station_address, 0x0120, 2);
+    EC_WRITE_U16(command->data, slave->current_state);
+    ec_master_queue_command(fsm->master, command);
+    fsm->change_state = ec_fsm_change_ack;
+}
+
+/*****************************************************************************/
+
+/**
+   Change state: ACK.
+*/
+
+void ec_fsm_change_ack(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+    ec_slave_t *slave = fsm->slave;
+
+    if (command->state != EC_CMD_RECEIVED || command->working_counter != 1) {
+        EC_ERR("Reception of state ack command failed.\n");
+        slave->state_error = 1;
+        fsm->change_state = ec_fsm_change_error;
+        return;
+    }
+
+    // read new AL status
+    ec_command_nprd(command, slave->station_address, 0x0130, 2);
+    ec_master_queue_command(fsm->master, command);
+    fsm->change_state = ec_fsm_change_ack2;
+}
+
+/*****************************************************************************/
+
+/**
+   Change state: ACK.
+   Acknowledge 2.
+*/
+
+void ec_fsm_change_ack2(ec_fsm_t *fsm /**< finite state machine */)
+{
+    ec_command_t *command = &fsm->command;
+    ec_slave_t *slave = fsm->slave;
+
+    if (command->state != EC_CMD_RECEIVED || command->working_counter != 1) {
+        EC_ERR("Reception of state ack check command failed.\n");
+        slave->state_error = 1;
+        fsm->change_state = ec_fsm_change_error;
+        return;
+    }
+
+    slave->current_state = EC_READ_U8(command->data);
+
+    if (slave->current_state == fsm->change_new) {
+        EC_INFO("Acknowleged state 0x%02X on slave %i.\n",
+                slave->current_state, slave->ring_position);
+        slave->state_error = 1;
+        fsm->change_state = ec_fsm_change_error;
+        return;
+    }
+
+    EC_WARN("Failed to acknowledge state 0x%02X on slave %i"
+            " - Timeout!\n", fsm->change_new, slave->ring_position);
+    slave->state_error = 1;
+    fsm->change_state = ec_fsm_change_error;
+}
+
+/*****************************************************************************/
+
+/**
+   Change state: END.
+*/
+
+void ec_fsm_change_end(ec_fsm_t *fsm /**< finite state machine */)
+{
+}
+
+/*****************************************************************************/
+
+/**
+   Change state: ERROR.
+*/
+
+void ec_fsm_change_error(ec_fsm_t *fsm /**< finite state machine */)
+{
+}
+
+/*****************************************************************************/
+
+/**
+   Application layer status messages.
+*/
+
+const ec_code_msg_t al_status_messages[] = {
+    {0x0001, "Unspecified error"},
+    {0x0011, "Invalud requested state change"},
+    {0x0012, "Unknown requested state"},
+    {0x0013, "Bootstrap not supported"},
+    {0x0014, "No valid firmware"},
+    {0x0015, "Invalid mailbox configuration"},
+    {0x0016, "Invalid mailbox configuration"},
+    {0x0017, "Invalid sync manager configuration"},
+    {0x0018, "No valid inputs available"},
+    {0x0019, "No valid outputs"},
+    {0x001A, "Synchronisation error"},
+    {0x001B, "Sync manager watchdog"},
+    {0x0020, "Slave needs cold start"},
+    {0x0021, "Slave needs INIT"},
+    {0x0022, "Slave needs PREOP"},
+    {0x0023, "Slave needs SAVEOP"},
+    {}
+};
+
+/*****************************************************************************/