master/fsm.c
changeset 238 b4960499098f
child 246 0bf7c769de06
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/master/fsm.c	Tue May 16 11:57:06 2006 +0000
@@ -0,0 +1,787 @@
+/******************************************************************************
+ *
+ *  $Id$
+ *
+ *  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; version 2 of the License.
+ *
+ *  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
+ *
+ *****************************************************************************/
+
+/**
+   \file
+   EtherCAT finite state machines.
+*/
+
+/*****************************************************************************/
+
+#include "globals.h"
+#include "fsm.h"
+#include "master.h"
+
+/*****************************************************************************/
+
+#define EC_CAT_MEM 0x100
+
+/*****************************************************************************/
+
+void ec_fsm_master_start(ec_fsm_t *);
+void ec_fsm_master_wait(ec_fsm_t *);
+void ec_fsm_master_slave(ec_fsm_t *);
+void ec_fsm_master_calc(ec_fsm_t *);
+void ec_fsm_master_finished(ec_fsm_t *);
+
+void ec_fsm_slave_start(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_categories(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_finished(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_finished(ec_fsm_t *);
+void ec_fsm_sii_error(ec_fsm_t *);
+
+/*****************************************************************************/
+
+int ec_fsm_init(ec_fsm_t *fsm, ec_master_t *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->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;
+}
+
+/*****************************************************************************/
+
+void ec_fsm_clear(ec_fsm_t *fsm)
+{
+    if (fsm->slave_cat_data) kfree(fsm->slave_cat_data);
+    ec_command_clear(&fsm->command);
+}
+
+/*****************************************************************************/
+
+void ec_fsm_reset(ec_fsm_t *fsm)
+{
+    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;
+    }
+}
+
+/*****************************************************************************/
+
+void ec_fsm_execute(ec_fsm_t *fsm)
+{
+    fsm->master_state(fsm);
+}
+
+/*****************************************************************************/
+
+int ec_fsm_idle(const ec_fsm_t *fsm)
+{
+    return (fsm->master_state == ec_fsm_master_start ||
+            fsm->master_state == ec_fsm_master_wait ||
+            fsm->master_state == ec_fsm_master_finished);
+}
+
+/******************************************************************************
+ *  master state machine
+ *****************************************************************************/
+
+/**
+   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_wait;
+}
+
+/*****************************************************************************/
+
+void ec_fsm_master_wait(ec_fsm_t *fsm)
+{
+    ec_command_t *command = &fsm->command;
+    unsigned int first, topology_change, i;
+    ec_slave_t *slave;
+
+    if (command->state != EC_CMD_RECEIVED) {
+        fsm->master_state = ec_fsm_master_start;
+        fsm->master_state(fsm); // execute immediately
+        return;
+    }
+
+    if (command->working_counter == fsm->master_slaves_responding &&
+        command->data[0] == fsm->master_slave_states) {
+        fsm->master_state = ec_fsm_master_start;
+        fsm->master_state(fsm); // execute immediately
+        return;
+    }
+
+    topology_change = command->working_counter !=
+        fsm->master_slaves_responding;
+
+    fsm->master_slaves_responding = command->working_counter;
+    fsm->master_slave_states = command->data[0];
+
+    EC_INFO("FSM: %i slave%s responding (", fsm->master_slaves_responding,
+            fsm->master_slaves_responding == 1 ? "" : "s");
+
+    first = 1;
+    if (fsm->master_slave_states & EC_SLAVE_STATE_INIT) {
+        printk("INIT");
+        first = 0;
+    }
+    if (fsm->master_slave_states & EC_SLAVE_STATE_PREOP) {
+        if (!first) printk(", ");
+        printk("PREOP");
+        first = 0;
+    }
+    if (fsm->master_slave_states & EC_SLAVE_STATE_SAVEOP) {
+        if (!first) printk(", ");
+        printk("SAVEOP");
+        first = 0;
+    }
+    if (fsm->master_slave_states & EC_SLAVE_STATE_OP) {
+        if (!first) printk(", ");
+        printk("OP");
+    }
+    printk(")\n");
+
+    if (!topology_change || fsm->master->mode == EC_MASTER_MODE_RUNNING) {
+        fsm->master_state = ec_fsm_master_start;
+        fsm->master_state(fsm); // execute immediately
+        return;
+    }
+
+    // topology change!
+    ec_master_clear_slaves(fsm->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("FSM failed to allocate slave %i!\n", i);
+            fsm->master_state = ec_fsm_master_finished;
+            return;
+        }
+
+        if (ec_slave_init(slave, fsm->master, i, i + 1)) {
+            fsm->master_state = ec_fsm_master_finished;
+            return;
+        }
+
+        if (kobject_add(&slave->kobj)) {
+            EC_ERR("FSM failed to add kobject.\n");
+            kobject_put(&slave->kobj); // free
+            fsm->master_state = ec_fsm_master_finished;
+            return;
+        }
+
+        list_add_tail(&slave->list, &fsm->master->slaves);
+    }
+
+    // begin scanning of slaves
+    fsm->slave = list_entry(fsm->master->slaves.next,
+                            ec_slave_t, list);
+    fsm->slave_state = ec_fsm_slave_start;
+
+    fsm->master_state = ec_fsm_master_slave;
+    fsm->master_state(fsm); // execute immediately
+}
+
+/*****************************************************************************/
+
+/**
+   State: Get Slave.
+   Executes the sub-statemachine of a slave.
+*/
+
+void ec_fsm_master_slave(ec_fsm_t *fsm)
+{
+    ec_master_t *master = fsm->master;
+
+    fsm->slave_state(fsm); // execute slave state machine
+
+    if (fsm->slave_state != ec_fsm_slave_finished) return;
+
+    // have all slaves been fetched?
+    if (fsm->slave->list.next == &master->slaves) {
+        fsm->master_state = ec_fsm_master_calc;
+        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;
+    fsm->slave_state(fsm); // execute immediately
+}
+
+/*****************************************************************************/
+
+/**
+   Free-Run state: Calc.
+*/
+
+void ec_fsm_master_calc(ec_fsm_t *fsm)
+{
+    uint16_t coupler_index, coupler_subindex;
+    uint16_t reverse_coupler_index, current_coupler_index;
+    ec_slave_t *slave;
+    ec_slave_ident_t *ident;
+    ec_master_t *master = fsm->master;
+
+    coupler_index = 0;
+    reverse_coupler_index = 0xFFFF;
+    current_coupler_index = 0x3FFF;
+    coupler_subindex = 0;
+
+    // for every slave on the bus
+    list_for_each_entry(slave, &master->slaves, list)
+    {
+        // search for identification in "database"
+        ident = slave_idents;
+        while (ident->type) {
+            if (unlikely(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 (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;
+        }
+
+        slave->coupler_index = current_coupler_index;
+        slave->coupler_subindex = coupler_subindex;
+        coupler_subindex++;
+    }
+
+    fsm->master_state = ec_fsm_master_start;
+    fsm->master_state(fsm); // execute immediately
+}
+
+/*****************************************************************************/
+
+/**
+   Free-Run state: Finished.
+   End state of the state machine. Does nothing.
+*/
+
+void ec_fsm_master_finished(ec_fsm_t *fsm)
+{
+}
+
+/******************************************************************************
+ *  slave state machine
+ *****************************************************************************/
+
+/**
+   Slave state: Start.
+   First state of the slave state machine. Writes the station address to the
+   slave, according to its ring position.
+*/
+
+void ec_fsm_slave_start(ec_fsm_t *fsm)
+{
+    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_base;
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: Read base.
+*/
+
+void ec_fsm_slave_read_base(ec_fsm_t *fsm)
+{
+    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_finished;
+        return;
+    }
+
+    // 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)
+{
+    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_finished;
+        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)
+{
+    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_finished;
+        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_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)
+{
+    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_finished;
+        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_finished) 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_state = ec_fsm_slave_categories;
+            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: Categories.
+*/
+
+void ec_fsm_slave_categories(ec_fsm_t *fsm)
+{
+    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_finished;
+        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
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: Read categories.
+   Start reading categories.
+*/
+
+void ec_fsm_slave_category_header(ec_fsm_t *fsm)
+{
+    // 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_finished;
+        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_finished) 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_finished;
+        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_finished;
+        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_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)
+{
+    // 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_finished;
+        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_finished) 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_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_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_finished;
+}
+
+/*****************************************************************************/
+
+/**
+   Slave state: Finished.
+   End state of the slave state machine.
+*/
+
+void ec_fsm_slave_finished(ec_fsm_t *fsm)
+{
+}
+
+/******************************************************************************
+ *  SII state machine
+ *****************************************************************************/
+
+/**
+   Slave SII state: Start reading.
+   Starts reading the slave information interface.
+*/
+
+void ec_fsm_sii_start_reading(ec_fsm_t *fsm)
+{
+    ec_command_t *command = &fsm->command;
+
+    // initiate read operation
+    ec_command_npwr(command, fsm->slave->station_address, 0x502, 6);
+    EC_WRITE_U8 (command->data,     0x00); // read-only access
+    EC_WRITE_U8 (command->data + 1, 0x01); // request read operation
+    EC_WRITE_U32(command->data + 2, fsm->sii_offset);
+    ec_master_queue_command(fsm->master, command);
+    fsm->sii_state = ec_fsm_sii_check;
+}
+
+/*****************************************************************************/
+
+/**
+   Slave 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)
+{
+    ec_command_t *command = &fsm->command;
+
+    if (command->state != EC_CMD_RECEIVED || command->working_counter != 1) {
+        EC_ERR("FSM SII: Reception of check command failed.\n");
+        fsm->sii_state = ec_fsm_sii_error;
+        return;
+    }
+
+    ec_command_nprd(command, fsm->slave->station_address, 0x502, 10);
+    ec_master_queue_command(fsm->master, command);
+    fsm->sii_state = ec_fsm_sii_fetch;
+}
+
+/*****************************************************************************/
+
+/**
+   Slave SII state: Fetch.
+   Fetches the result of an SII-read command.
+*/
+
+void ec_fsm_sii_fetch(ec_fsm_t *fsm)
+{
+    ec_command_t *command = &fsm->command;
+
+    if (command->state != EC_CMD_RECEIVED || command->working_counter != 1) {
+        EC_ERR("FSM SII: Reception of fetch command failed.\n");
+        fsm->sii_state = ec_fsm_sii_error;
+        return;
+    }
+
+    // check "busy bit"
+    if (likely((EC_READ_U8(command->data + 1) & 0x81) == 0)) {
+        fsm->sii_result = EC_READ_U32(command->data + 6);
+        fsm->sii_state = ec_fsm_sii_finished;
+    }
+}
+
+/*****************************************************************************/
+
+/**
+   Slave SII state: Finished.
+   End state of the slave SII state machine.
+*/
+
+void ec_fsm_sii_finished(ec_fsm_t *fsm)
+{
+}
+
+/*****************************************************************************/
+
+/**
+   Slave SII state: Error.
+   End state of the slave SII state machine.
+*/
+
+void ec_fsm_sii_error(ec_fsm_t *fsm)
+{
+}
+
+/*****************************************************************************/