// SPDX-License-Identifier: GPL-2.0+
/*
 * IUCV network driver
 *
 * Copyright IBM Corp. 2001, 2009
 *
 * Author(s):
 *      Original netiucv driver:
 *              Fritz Elfert (elfert@de.ibm.com, felfert@millenux.com)
 *      Sysfs integration and all bugs therein:
 *              Cornelia Huck (cornelia.huck@de.ibm.com)
 *      PM functions:
 *              Ursula Braun (ursula.braun@de.ibm.com)
 *
 * Documentation used:
 *  the source of the original IUCV driver by:
 *    Stefan Hegewald <hegewald@de.ibm.com>
 *    Hartmut Penner <hpenner@de.ibm.com>
 *    Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
 *    Martin Schwidefsky (schwidefsky@de.ibm.com)
 *    Alan Altmark (Alan_Altmark@us.ibm.com)  Sept. 2000
 */

#define KMSG_COMPONENT "netiucv"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#undef DEBUG

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/interrupt.h>
#include <linux/timer.h>
#include <linux/bitops.h>

#include <linux/signal.h>
#include <linux/string.h>
#include <linux/device.h>

#include <linux/ip.h>
#include <linux/if_arp.h>
#include <linux/tcp.h>
#include <linux/skbuff.h>
#include <linux/ctype.h>
#include <net/dst.h>

#include <asm/io.h>
#include <linux/uaccess.h>
#include <asm/ebcdic.h>

#include <net/iucv/iucv.h>
#include "fsm.h"

MODULE_AUTHOR
    ("(C) 2001 IBM Corporation by Fritz Elfert (felfert@millenux.com)");
MODULE_DESCRIPTION ("Linux for S/390 IUCV network driver");

/**
 * Debug Facility stuff
 */
#define IUCV_DBF_SETUP_NAME "iucv_setup"
#define IUCV_DBF_SETUP_LEN 64
#define IUCV_DBF_SETUP_PAGES 2
#define IUCV_DBF_SETUP_NR_AREAS 1
#define IUCV_DBF_SETUP_LEVEL 3

#define IUCV_DBF_DATA_NAME "iucv_data"
#define IUCV_DBF_DATA_LEN 128
#define IUCV_DBF_DATA_PAGES 2
#define IUCV_DBF_DATA_NR_AREAS 1
#define IUCV_DBF_DATA_LEVEL 2

#define IUCV_DBF_TRACE_NAME "iucv_trace"
#define IUCV_DBF_TRACE_LEN 16
#define IUCV_DBF_TRACE_PAGES 4
#define IUCV_DBF_TRACE_NR_AREAS 1
#define IUCV_DBF_TRACE_LEVEL 3

#define IUCV_DBF_TEXT(name,level,text) \
        do { \
                debug_text_event(iucv_dbf_##name,level,text); \
        } while (0)

#define IUCV_DBF_HEX(name,level,addr,len) \
        do { \
                debug_event(iucv_dbf_##name,level,(void*)(addr),len); \
        } while (0)

DECLARE_PER_CPU(char[256], iucv_dbf_txt_buf);

#define IUCV_DBF_TEXT_(name, level, text...) \
        do { \
                if (debug_level_enabled(iucv_dbf_##name, level)) { \
                        char* __buf = get_cpu_var(iucv_dbf_txt_buf); \
                        sprintf(__buf, text); \
                        debug_text_event(iucv_dbf_##name, level, __buf); \
                        put_cpu_var(iucv_dbf_txt_buf); \
                } \
        } while (0)

#define IUCV_DBF_SPRINTF(name,level,text...) \
        do { \
                debug_sprintf_event(iucv_dbf_trace, level, ##text ); \
                debug_sprintf_event(iucv_dbf_trace, level, text ); \
        } while (0)

/**
 * some more debug stuff
 */
#define PRINTK_HEADER " iucv: "       /* for debugging */

/* dummy device to make sure netiucv_pm functions are called */
static struct device *netiucv_dev;

static int netiucv_pm_prepare(struct device *);
static void netiucv_pm_complete(struct device *);
static int netiucv_pm_freeze(struct device *);
static int netiucv_pm_restore_thaw(struct device *);

static const struct dev_pm_ops netiucv_pm_ops = {
        .prepare = netiucv_pm_prepare,
        .complete = netiucv_pm_complete,
        .freeze = netiucv_pm_freeze,
        .thaw = netiucv_pm_restore_thaw,
        .restore = netiucv_pm_restore_thaw,
};

static struct device_driver netiucv_driver = {
        .owner = THIS_MODULE,
        .name = "netiucv",
        .bus  = &iucv_bus,
        .pm = &netiucv_pm_ops,
};

static int netiucv_callback_connreq(struct iucv_path *, u8 *, u8 *);
static void netiucv_callback_connack(struct iucv_path *, u8 *);
static void netiucv_callback_connrej(struct iucv_path *, u8 *);
static void netiucv_callback_connsusp(struct iucv_path *, u8 *);
static void netiucv_callback_connres(struct iucv_path *, u8 *);
static void netiucv_callback_rx(struct iucv_path *, struct iucv_message *);
static void netiucv_callback_txdone(struct iucv_path *, struct iucv_message *);

static struct iucv_handler netiucv_handler = {
        .path_pending     = netiucv_callback_connreq,
        .path_complete    = netiucv_callback_connack,
        .path_severed     = netiucv_callback_connrej,
        .path_quiesced    = netiucv_callback_connsusp,
        .path_resumed     = netiucv_callback_connres,
        .message_pending  = netiucv_callback_rx,
        .message_complete = netiucv_callback_txdone
};

/**
 * Per connection profiling data
 */
struct connection_profile {
        unsigned long maxmulti;
        unsigned long maxcqueue;
        unsigned long doios_single;
        unsigned long doios_multi;
        unsigned long txlen;
        unsigned long tx_time;
        unsigned long send_stamp;
        unsigned long tx_pending;
        unsigned long tx_max_pending;
};

/**
 * Representation of one iucv connection
 */
struct iucv_connection {
        struct list_head          list;
        struct iucv_path          *path;
        struct sk_buff            *rx_buff;
        struct sk_buff            *tx_buff;
        struct sk_buff_head       collect_queue;
        struct sk_buff_head       commit_queue;
        spinlock_t                collect_lock;
        int                       collect_len;
        int                       max_buffsize;
        fsm_timer                 timer;
        fsm_instance              *fsm;
        struct net_device         *netdev;
        struct connection_profile prof;
        char                      userid[9];
        char                      userdata[17];
};

/**
 * Linked list of all connection structs.
 */
static LIST_HEAD(iucv_connection_list);
static DEFINE_RWLOCK(iucv_connection_rwlock);

/**
 * Representation of event-data for the
 * connection state machine.
 */
struct iucv_event {
        struct iucv_connection *conn;
        void                   *data;
};

/**
 * Private part of the network device structure
 */
struct netiucv_priv {
        struct net_device_stats stats;
        unsigned long           tbusy;
        fsm_instance            *fsm;
        struct iucv_connection  *conn;
        struct device           *dev;
        int                      pm_state;
};

/**
 * Link level header for a packet.
 */
struct ll_header {
        u16 next;
};

#define NETIUCV_HDRLEN           (sizeof(struct ll_header))
#define NETIUCV_BUFSIZE_MAX      65537
#define NETIUCV_BUFSIZE_DEFAULT  NETIUCV_BUFSIZE_MAX
#define NETIUCV_MTU_MAX          (NETIUCV_BUFSIZE_MAX - NETIUCV_HDRLEN)
#define NETIUCV_MTU_DEFAULT      9216
#define NETIUCV_QUEUELEN_DEFAULT 50
#define NETIUCV_TIMEOUT_5SEC     5000

/**
 * Compatibility macros for busy handling
 * of network devices.
 */
static void netiucv_clear_busy(struct net_device *dev)
{
        struct netiucv_priv *priv = netdev_priv(dev);
        clear_bit(0, &priv->tbusy);
        netif_wake_queue(dev);
}

static int netiucv_test_and_set_busy(struct net_device *dev)
{
        struct netiucv_priv *priv = netdev_priv(dev);
        netif_stop_queue(dev);
        return test_and_set_bit(0, &priv->tbusy);
}

static u8 iucvMagic_ascii[16] = {
        0x30, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
        0x30, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20
};

static u8 iucvMagic_ebcdic[16] = {
        0xF0, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
        0xF0, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40
};

/**
 * Convert an iucv userId to its printable
 * form (strip whitespace at end).
 *
 * @param An iucv userId
 *
 * @returns The printable string (static data!!)
 */
static char *netiucv_printname(char *name, int len)
{
        static char tmp[17];
        char *p = tmp;
        memcpy(tmp, name, len);
        tmp[len] = '\0';
        while (*p && ((p - tmp) < len) && (!isspace(*p)))
                p++;
        *p = '\0';
        return tmp;
}

static char *netiucv_printuser(struct iucv_connection *conn)
{
        static char tmp_uid[9];
        static char tmp_udat[17];
        static char buf[100];

        if (memcmp(conn->userdata, iucvMagic_ebcdic, 16)) {
                tmp_uid[8] = '\0';
                tmp_udat[16] = '\0';
                memcpy(tmp_uid, netiucv_printname(conn->userid, 8), 8);
                memcpy(tmp_udat, conn->userdata, 16);
                EBCASC(tmp_udat, 16);
                memcpy(tmp_udat, netiucv_printname(tmp_udat, 16), 16);
                sprintf(buf, "%s.%s", tmp_uid, tmp_udat);
                return buf;
        } else
                return netiucv_printname(conn->userid, 8);
}

/**
 * States of the interface statemachine.
 */
enum dev_states {
        DEV_STATE_STOPPED,
        DEV_STATE_STARTWAIT,
        DEV_STATE_STOPWAIT,
        DEV_STATE_RUNNING,
        /**
         * MUST be always the last element!!
         */
        NR_DEV_STATES
};

static const char *dev_state_names[] = {
        "Stopped",
        "StartWait",
        "StopWait",
        "Running",
};

/**
 * Events of the interface statemachine.
 */
enum dev_events {
        DEV_EVENT_START,
        DEV_EVENT_STOP,
        DEV_EVENT_CONUP,
        DEV_EVENT_CONDOWN,
        /**
         * MUST be always the last element!!
         */
        NR_DEV_EVENTS
};

static const char *dev_event_names[] = {
        "Start",
        "Stop",
        "Connection up",
        "Connection down",
};

/**
 * Events of the connection statemachine
 */
enum conn_events {
        /**
         * Events, representing callbacks from
         * lowlevel iucv layer)
         */
        CONN_EVENT_CONN_REQ,
        CONN_EVENT_CONN_ACK,
        CONN_EVENT_CONN_REJ,
        CONN_EVENT_CONN_SUS,
        CONN_EVENT_CONN_RES,
        CONN_EVENT_RX,
        CONN_EVENT_TXDONE,

        /**
         * Events, representing errors return codes from
         * calls to lowlevel iucv layer
         */

        /**
         * Event, representing timer expiry.
         */
        CONN_EVENT_TIMER,

        /**
         * Events, representing commands from upper levels.
         */
        CONN_EVENT_START,
        CONN_EVENT_STOP,

        /**
         * MUST be always the last element!!
         */
        NR_CONN_EVENTS,
};

static const char *conn_event_names[] = {
        "Remote connection request",
        "Remote connection acknowledge",
        "Remote connection reject",
        "Connection suspended",
        "Connection resumed",
        "Data received",
        "Data sent",

        "Timer",

        "Start",
        "Stop",
};

/**
 * States of the connection statemachine.
 */
enum conn_states {
        /**
         * Connection not assigned to any device,
         * initial state, invalid
         */
        CONN_STATE_INVALID,

        /**
         * Userid assigned but not operating
         */
        CONN_STATE_STOPPED,

        /**
         * Connection registered,
         * no connection request sent yet,
         * no connection request received
         */
        CONN_STATE_STARTWAIT,

        /**
         * Connection registered and connection request sent,
         * no acknowledge and no connection request received yet.
         */
        CONN_STATE_SETUPWAIT,

        /**
         * Connection up and running idle
         */
        CONN_STATE_IDLE,

        /**
         * Data sent, awaiting CONN_EVENT_TXDONE
         */
        CONN_STATE_TX,

        /**
         * Error during registration.
         */
        CONN_STATE_REGERR,

        /**
         * Error during registration.
         */
        CONN_STATE_CONNERR,

        /**
         * MUST be always the last element!!
         */
        NR_CONN_STATES,
};

static const char *conn_state_names[] = {
        "Invalid",
        "Stopped",
        "StartWait",
        "SetupWait",
        "Idle",
        "TX",
        "Terminating",
        "Registration error",
        "Connect error",
};


/**
 * Debug Facility Stuff
 */
static debug_info_t *iucv_dbf_setup = NULL;
static debug_info_t *iucv_dbf_data = NULL;
static debug_info_t *iucv_dbf_trace = NULL;

DEFINE_PER_CPU(char[256], iucv_dbf_txt_buf);

static void iucv_unregister_dbf_views(void)
{
        debug_unregister(iucv_dbf_setup);
        debug_unregister(iucv_dbf_data);
        debug_unregister(iucv_dbf_trace);
}
static int iucv_register_dbf_views(void)
{
        iucv_dbf_setup = debug_register(IUCV_DBF_SETUP_NAME,
                                        IUCV_DBF_SETUP_PAGES,
                                        IUCV_DBF_SETUP_NR_AREAS,
                                        IUCV_DBF_SETUP_LEN);
        iucv_dbf_data = debug_register(IUCV_DBF_DATA_NAME,
                                       IUCV_DBF_DATA_PAGES,
                                       IUCV_DBF_DATA_NR_AREAS,
                                       IUCV_DBF_DATA_LEN);
        iucv_dbf_trace = debug_register(IUCV_DBF_TRACE_NAME,
                                        IUCV_DBF_TRACE_PAGES,
                                        IUCV_DBF_TRACE_NR_AREAS,
                                        IUCV_DBF_TRACE_LEN);

        if ((iucv_dbf_setup == NULL) || (iucv_dbf_data == NULL) ||
            (iucv_dbf_trace == NULL)) {
                iucv_unregister_dbf_views();
                return -ENOMEM;
        }
        debug_register_view(iucv_dbf_setup, &debug_hex_ascii_view);
        debug_set_level(iucv_dbf_setup, IUCV_DBF_SETUP_LEVEL);

        debug_register_view(iucv_dbf_data, &debug_hex_ascii_view);
        debug_set_level(iucv_dbf_data, IUCV_DBF_DATA_LEVEL);

        debug_register_view(iucv_dbf_trace, &debug_hex_ascii_view);
        debug_set_level(iucv_dbf_trace, IUCV_DBF_TRACE_LEVEL);

        return 0;
}

/*
 * Callback-wrappers, called from lowlevel iucv layer.
 */

static void netiucv_callback_rx(struct iucv_path *path,
                                struct iucv_message *msg)
{
        struct iucv_connection *conn = path->private;
        struct iucv_event ev;

        ev.conn = conn;
        ev.data = msg;
        fsm_event(conn->fsm, CONN_EVENT_RX, &ev);
}

static void netiucv_callback_txdone(struct iucv_path *path,
                                    struct iucv_message *msg)
{
        struct iucv_connection *conn = path->private;
        struct iucv_event ev;

        ev.conn = conn;
        ev.data = msg;
        fsm_event(conn->fsm, CONN_EVENT_TXDONE, &ev);
}

static void netiucv_callback_connack(struct iucv_path *path, u8 ipuser[16])
{
        struct iucv_connection *conn = path->private;

        fsm_event(conn->fsm, CONN_EVENT_CONN_ACK, conn);
}

static int netiucv_callback_connreq(struct iucv_path *path, u8 *ipvmid,
                                    u8 *ipuser)
{
        struct iucv_connection *conn = path->private;
        struct iucv_event ev;
        static char tmp_user[9];
        static char tmp_udat[17];
        int rc;

        rc = -EINVAL;
        memcpy(tmp_user, netiucv_printname(ipvmid, 8), 8);
        memcpy(tmp_udat, ipuser, 16);
        EBCASC(tmp_udat, 16);
        read_lock_bh(&iucv_connection_rwlock);
        list_for_each_entry(conn, &iucv_connection_list, list) {
                if (strncmp(ipvmid, conn->userid, 8) ||
                    strncmp(ipuser, conn->userdata, 16))
                        continue;
                /* Found a matching connection for this path. */
                conn->path = path;
                ev.conn = conn;
                ev.data = path;
                fsm_event(conn->fsm, CONN_EVENT_CONN_REQ, &ev);
                rc = 0;
        }
        IUCV_DBF_TEXT_(setup, 2, "Connection requested for %s.%s\n",
                       tmp_user, netiucv_printname(tmp_udat, 16));
        read_unlock_bh(&iucv_connection_rwlock);
        return rc;
}

static void netiucv_callback_connrej(struct iucv_path *path, u8 *ipuser)
{
        struct iucv_connection *conn = path->private;

        fsm_event(conn->fsm, CONN_EVENT_CONN_REJ, conn);
}

static void netiucv_callback_connsusp(struct iucv_path *path, u8 *ipuser)
{
        struct iucv_connection *conn = path->private;

        fsm_event(conn->fsm, CONN_EVENT_CONN_SUS, conn);
}

static void netiucv_callback_connres(struct iucv_path *path, u8 *ipuser)
{
        struct iucv_connection *conn = path->private;

        fsm_event(conn->fsm, CONN_EVENT_CONN_RES, conn);
}

/**
 * NOP action for statemachines
 */
static void netiucv_action_nop(fsm_instance *fi, int event, void *arg)
{
}

/*
 * Actions of the connection statemachine
 */

/**
 * netiucv_unpack_skb
 * @conn: The connection where this skb has been received.
 * @pskb: The received skb.
 *
 * Unpack a just received skb and hand it over to upper layers.
 * Helper function for conn_action_rx.
 */
static void netiucv_unpack_skb(struct iucv_connection *conn,
                               struct sk_buff *pskb)
{
        struct net_device     *dev = conn->netdev;
        struct netiucv_priv   *privptr = netdev_priv(dev);
        u16 offset = 0;

        skb_put(pskb, NETIUCV_HDRLEN);
        pskb->dev = dev;
        pskb->ip_summed = CHECKSUM_NONE;
        pskb->protocol = cpu_to_be16(ETH_P_IP);

        while (1) {
                struct sk_buff *skb;
                struct ll_header *header = (struct ll_header *) pskb->data;

                if (!header->next)
                        break;

                skb_pull(pskb, NETIUCV_HDRLEN);
                header->next -= offset;
                offset += header->next;
                header->next -= NETIUCV_HDRLEN;
                if (skb_tailroom(pskb) < header->next) {
                        IUCV_DBF_TEXT_(data, 2, "Illegal next field: %d > %d\n",
                                header->next, skb_tailroom(pskb));
                        return;
                }
                skb_put(pskb, header->next);
                skb_reset_mac_header(pskb);
                skb = dev_alloc_skb(pskb->len);
                if (!skb) {
                        IUCV_DBF_TEXT(data, 2,
                                "Out of memory in netiucv_unpack_skb\n");
                        privptr->stats.rx_dropped++;
                        return;
                }
                skb_copy_from_linear_data(pskb, skb_put(skb, pskb->len),
                                          pskb->len);
                skb_reset_mac_header(skb);
                skb->dev = pskb->dev;
                skb->protocol = pskb->protocol;
                pskb->ip_summed = CHECKSUM_UNNECESSARY;
                privptr->stats.rx_packets++;
                privptr->stats.rx_bytes += skb->len;
                /*
                 * Since receiving is always initiated from a tasklet (in iucv.c),
                 * we must use netif_rx_ni() instead of netif_rx()
                 */
                netif_rx_ni(skb);
                skb_pull(pskb, header->next);
                skb_put(pskb, NETIUCV_HDRLEN);
        }
}

static void conn_action_rx(fsm_instance *fi, int event, void *arg)
{
        struct iucv_event *ev = arg;
        struct iucv_connection *conn = ev->conn;
        struct iucv_message *msg = ev->data;
        struct netiucv_priv *privptr = netdev_priv(conn->netdev);
        int rc;

        IUCV_DBF_TEXT(trace, 4, __func__);

        if (!conn->netdev) {
                iucv_message_reject(conn->path, msg);
                IUCV_DBF_TEXT(data, 2,
                              "Received data for unlinked connection\n");
                return;
        }
        if (msg->length > conn->max_buffsize) {
                iucv_message_reject(conn->path, msg);
                privptr->stats.rx_dropped++;
                IUCV_DBF_TEXT_(data, 2, "msglen %d > max_buffsize %d\n",
                               msg->length, conn->max_buffsize);
                return;
        }
        conn->rx_buff->data = conn->rx_buff->head;
        skb_reset_tail_pointer(conn->rx_buff);
        conn->rx_buff->len = 0;
        rc = iucv_message_receive(conn->path, msg, 0, conn->rx_buff->data,
                                  msg->length, NULL);
        if (rc || msg->length < 5) {
                privptr->stats.rx_errors++;
                IUCV_DBF_TEXT_(data, 2, "rc %d from iucv_receive\n", rc);
                return;
        }
        netiucv_unpack_skb(conn, conn->rx_buff);
}

static void conn_action_txdone(fsm_instance *fi, int event, void *arg)
{
        struct iucv_event *ev = arg;
        struct iucv_connection *conn = ev->conn;
        struct iucv_message *msg = ev->data;
        struct iucv_message txmsg;
        struct netiucv_priv *privptr = NULL;
        u32 single_flag = msg->tag;
        u32 txbytes = 0;
        u32 txpackets = 0;
        u32 stat_maxcq = 0;
        struct sk_buff *skb;
        unsigned long saveflags;
        struct ll_header header;
        int rc;

        IUCV_DBF_TEXT(trace, 4, __func__);

        if (!conn || !conn->netdev) {
                IUCV_DBF_TEXT(data, 2,
                              "Send confirmation for unlinked connection\n");
                return;
        }
        privptr = netdev_priv(conn->netdev);
        conn->prof.tx_pending--;
        if (single_flag) {
                if ((skb = skb_dequeue(&conn->commit_queue))) {
                        refcount_dec(&skb->users);
                        if (privptr) {
                                privptr->stats.tx_packets++;
                                privptr->stats.tx_bytes +=
                                        (skb->len - NETIUCV_HDRLEN
                                                  - NETIUCV_HDRLEN);
                        }
                        dev_kfree_skb_any(skb);
                }
        }
        conn->tx_buff->data = conn->tx_buff->head;
        skb_reset_tail_pointer(conn->tx_buff);
        conn->tx_buff->len = 0;
        spin_lock_irqsave(&conn->collect_lock, saveflags);
        while ((skb = skb_dequeue(&conn->collect_queue))) {
                header.next = conn->tx_buff->len + skb->len + NETIUCV_HDRLEN;
                skb_put_data(conn->tx_buff, &header, NETIUCV_HDRLEN);
                skb_copy_from_linear_data(skb,
                                          skb_put(conn->tx_buff, skb->len),
                                          skb->len);
                txbytes += skb->len;
                txpackets++;
                stat_maxcq++;
                refcount_dec(&skb->users);
                dev_kfree_skb_any(skb);
        }
        if (conn->collect_len > conn->prof.maxmulti)
                conn->prof.maxmulti = conn->collect_len;
        conn->collect_len = 0;
        spin_unlock_irqrestore(&conn->collect_lock, saveflags);
        if (conn->tx_buff->len == 0) {
                fsm_newstate(fi, CONN_STATE_IDLE);
                return;
        }

        header.next = 0;
        skb_put_data(conn->tx_buff, &header, NETIUCV_HDRLEN);
        conn->prof.send_stamp = jiffies;
        txmsg.class = 0;
        txmsg.tag = 0;
        rc = iucv_message_send(conn->path, &txmsg, 0, 0,
                               conn->tx_buff->data, conn->tx_buff->len);
        conn->prof.doios_multi++;
        conn->prof.txlen += conn->tx_buff->len;
        conn->prof.tx_pending++;
        if (conn->prof.tx_pending > conn->prof.tx_max_pending)
                conn->prof.tx_max_pending = conn->prof.tx_pending;
        if (rc) {
                conn->prof.tx_pending--;
                fsm_newstate(fi, CONN_STATE_IDLE);
                if (privptr)
                        privptr->stats.tx_errors += txpackets;
                IUCV_DBF_TEXT_(data, 2, "rc %d from iucv_send\n", rc);
        } else {
                if (privptr) {
                        privptr->stats.tx_packets += txpackets;
                        privptr->stats.tx_bytes += txbytes;
                }
                if (stat_maxcq > conn->prof.maxcqueue)
                        conn->prof.maxcqueue = stat_maxcq;
        }
}

static void conn_action_connaccept(fsm_instance *fi, int event, void *arg)
{
        struct iucv_event *ev = arg;
        struct iucv_connection *conn = ev->conn;
        struct iucv_path *path = ev->data;
        struct net_device *netdev = conn->netdev;
        struct netiucv_priv *privptr = netdev_priv(netdev);
        int rc;

        IUCV_DBF_TEXT(trace, 3, __func__);

        conn->path = path;
        path->msglim = NETIUCV_QUEUELEN_DEFAULT;
        path->flags = 0;
        rc = iucv_path_accept(path, &netiucv_handler, conn->userdata , conn);
        if (rc) {
                IUCV_DBF_TEXT_(setup, 2, "rc %d from iucv_accept", rc);
                return;
        }
        fsm_newstate(fi, CONN_STATE_IDLE);
        netdev->tx_queue_len = conn->path->msglim;
        fsm_event(privptr->fsm, DEV_EVENT_CONUP, netdev);
}

static void conn_action_connreject(fsm_instance *fi, int event, void *arg)
{
        struct iucv_event *ev = arg;
        struct iucv_path *path = ev->data;

        IUCV_DBF_TEXT(trace, 3, __func__);
        iucv_path_sever(path, NULL);
}

static void conn_action_connack(fsm_instance *fi, int event, void *arg)
{
        struct iucv_connection *conn = arg;
        struct net_device *netdev = conn->netdev;
        struct netiucv_priv *privptr = netdev_priv(netdev);

        IUCV_DBF_TEXT(trace, 3, __func__);
        fsm_deltimer(&conn->timer);
        fsm_newstate(fi, CONN_STATE_IDLE);
        netdev->tx_queue_len = conn->path->msglim;
        fsm_event(privptr->fsm, DEV_EVENT_CONUP, netdev);
}

static void conn_action_conntimsev(fsm_instance *fi, int event, void *arg)
{
        struct iucv_connection *conn = arg;

        IUCV_DBF_TEXT(trace, 3, __func__);
        fsm_deltimer(&conn->timer);
        iucv_path_sever(conn->path, conn->userdata);
        fsm_newstate(fi, CONN_STATE_STARTWAIT);
}

static void conn_action_connsever(fsm_instance *fi, int event, void *arg)
{
        struct iucv_connection *conn = arg;
        struct net_device *netdev = conn->netdev;
        struct netiucv_priv *privptr = netdev_priv(netdev);

        IUCV_DBF_TEXT(trace, 3, __func__);

        fsm_deltimer(&conn->timer);
        iucv_path_sever(conn->path, conn->userdata);
        dev_info(privptr->dev, "The peer z/VM guest %s has closed the "
                               "connection\n", netiucv_printuser(conn));
        IUCV_DBF_TEXT(data, 2,
                      "conn_action_connsever: Remote dropped connection\n");
        fsm_newstate(fi, CONN_STATE_STARTWAIT);
        fsm_event(privptr->fsm, DEV_EVENT_CONDOWN, netdev);
}

static void conn_action_start(fsm_instance *fi, int event, void *arg)
{
        struct iucv_connection *conn = arg;
        struct net_device *netdev = conn->netdev;
        struct netiucv_priv *privptr = netdev_priv(netdev);
        int rc;

        IUCV_DBF_TEXT(trace, 3, __func__);

        fsm_newstate(fi, CONN_STATE_STARTWAIT);

        /*
         * We must set the state before calling iucv_connect because the
         * callback handler could be called at any point after the connection
         * request is sent
         */

        fsm_newstate(fi, CONN_STATE_SETUPWAIT);
        conn->path = iucv_path_alloc(NETIUCV_QUEUELEN_DEFAULT, 0, GFP_KERNEL);
        IUCV_DBF_TEXT_(setup, 2, "%s: connecting to %s ...\n",
                netdev->name, netiucv_printuser(conn));

        rc = iucv_path_connect(conn->path, &netiucv_handler, conn->userid,
                               NULL, conn->userdata, conn);
        switch (rc) {
        case 0:
                netdev->tx_queue_len = conn->path->msglim;
                fsm_addtimer(&conn->timer, NETIUCV_TIMEOUT_5SEC,
                             CONN_EVENT_TIMER, conn);
                return;
        case 11:
                dev_warn(privptr->dev,
                        "The IUCV device failed to connect to z/VM guest %s\n",
                        netiucv_printname(conn->userid, 8));
                fsm_newstate(fi, CONN_STATE_STARTWAIT);
                break;
        case 12:
                dev_warn(privptr->dev,
                        "The IUCV device failed to connect to the peer on z/VM"
                        " guest %s\n", netiucv_printname(conn->userid, 8));
                fsm_newstate(fi, CONN_STATE_STARTWAIT);
                break;
        case 13:
                dev_err(privptr->dev,
                        "Connecting the IUCV device would exceed the maximum"
                        " number of IUCV connections\n");
                fsm_newstate(fi, CONN_STATE_CONNERR);
                break;
        case 14:
                dev_err(privptr->dev,
                        "z/VM guest %s has too many IUCV connections"
                        " to connect with the IUCV device\n",
                        netiucv_printname(conn->userid, 8));
                fsm_newstate(fi, CONN_STATE_CONNERR);
                break;
        case 15:
                dev_err(privptr->dev,
                        "The IUCV device cannot connect to a z/VM guest with no"
                        " IUCV authorization\n");
                fsm_newstate(fi, CONN_STATE_CONNERR);
                break;
        default:
                dev_err(privptr->dev,
                        "Connecting the IUCV device failed with error %d\n",
                        rc);
                fsm_newstate(fi, CONN_STATE_CONNERR);
                break;
        }
        IUCV_DBF_TEXT_(setup, 5, "iucv_connect rc is %d\n", rc);
        kfree(conn->path);
        conn->path = NULL;
}

static void netiucv_purge_skb_queue(struct sk_buff_head *q)
{
        struct sk_buff *skb;

        while ((skb = skb_dequeue(q))) {
                refcount_dec(&skb->users);
                dev_kfree_skb_any(skb);
        }
}

static void conn_action_stop(fsm_instance *fi, int event, void *arg)
{
        struct iucv_event *ev = arg;
        struct iucv_connection *conn = ev->conn;
        struct net_device *netdev = conn->netdev;
        struct netiucv_priv *privptr = netdev_priv(netdev);

        IUCV_DBF_TEXT(trace, 3, __func__);

        fsm_deltimer(&conn->timer);
        fsm_newstate(fi, CONN_STATE_STOPPED);
        netiucv_purge_skb_queue(&conn->collect_queue);
        if (conn->path) {
                IUCV_DBF_TEXT(trace, 5, "calling iucv_path_sever\n");
                iucv_path_sever(conn->path, conn->userdata);
                kfree(conn->path);
                conn->path = NULL;
        }
        netiucv_purge_skb_queue(&conn->commit_queue);
        fsm_event(privptr->fsm, DEV_EVENT_CONDOWN, netdev);
}

static void conn_action_inval(fsm_instance *fi, int event, void *arg)
{
        struct iucv_connection *conn = arg;
        struct net_device *netdev = conn->netdev;

        IUCV_DBF_TEXT_(data, 2, "%s('%s'): conn_action_inval called\n",
                netdev->name, conn->userid);
}

static const fsm_node conn_fsm[] = {
        { CONN_STATE_INVALID,   CONN_EVENT_START,    conn_action_inval      },
        { CONN_STATE_STOPPED,   CONN_EVENT_START,    conn_action_start      },

        { CONN_STATE_STOPPED,   CONN_EVENT_STOP,     conn_action_stop       },
        { CONN_STATE_STARTWAIT, CONN_EVENT_STOP,     conn_action_stop       },
        { CONN_STATE_SETUPWAIT, CONN_EVENT_STOP,     conn_action_stop       },
        { CONN_STATE_IDLE,      CONN_EVENT_STOP,     conn_action_stop       },
        { CONN_STATE_TX,        CONN_EVENT_STOP,     conn_action_stop       },
        { CONN_STATE_REGERR,    CONN_EVENT_STOP,     conn_action_stop       },
        { CONN_STATE_CONNERR,   CONN_EVENT_STOP,     conn_action_stop       },

        { CONN_STATE_STOPPED,   CONN_EVENT_CONN_REQ, conn_action_connreject },
        { CONN_STATE_STARTWAIT, CONN_EVENT_CONN_REQ, conn_action_connaccept },
        { CONN_STATE_SETUPWAIT, CONN_EVENT_CONN_REQ, conn_action_connaccept },
        { CONN_STATE_IDLE,      CONN_EVENT_CONN_REQ, conn_action_connreject },
        { CONN_STATE_TX,        CONN_EVENT_CONN_REQ, conn_action_connreject },

        { CONN_STATE_SETUPWAIT, CONN_EVENT_CONN_ACK, conn_action_connack    },
        { CONN_STATE_SETUPWAIT, CONN_EVENT_TIMER,    conn_action_conntimsev },

        { CONN_STATE_SETUPWAIT, CONN_EVENT_CONN_REJ, conn_action_connsever  },
        { CONN_STATE_IDLE,      CONN_EVENT_CONN_REJ, conn_action_connsever  },
        { CONN_STATE_TX,        CONN_EVENT_CONN_REJ, conn_action_connsever  },

        { CONN_STATE_IDLE,      CONN_EVENT_RX,       conn_action_rx         },
        { CONN_STATE_TX,        CONN_EVENT_RX,       conn_action_rx         },

        { CONN_STATE_TX,        CONN_EVENT_TXDONE,   conn_action_txdone     },
        { CONN_STATE_IDLE,      CONN_EVENT_TXDONE,   conn_action_txdone     },
};

static const int CONN_FSM_LEN = sizeof(conn_fsm) / sizeof(fsm_node);


/*
 * Actions for interface - statemachine.
 */

/**
 * dev_action_start
 * @fi: An instance of an interface statemachine.
 * @event: The event, just happened.
 * @arg: Generic pointer, casted from struct net_device * upon call.
 *
 * Startup connection by sending CONN_EVENT_START to it.
 */
static void dev_action_start(fsm_instance *fi, int event, void *arg)
{
        struct net_device   *dev = arg;
        struct netiucv_priv *privptr = netdev_priv(dev);

        IUCV_DBF_TEXT(trace, 3, __func__);

        fsm_newstate(fi, DEV_STATE_STARTWAIT);
        fsm_event(privptr->conn->fsm, CONN_EVENT_START, privptr->conn);
}

/**
 * Shutdown connection by sending CONN_EVENT_STOP to it.
 *
 * @param fi    An instance of an interface statemachine.
 * @param event The event, just happened.
 * @param arg   Generic pointer, casted from struct net_device * upon call.
 */
static void
dev_action_stop(fsm_instance *fi, int event, void *arg)
{
        struct net_device   *dev = arg;
        struct netiucv_priv *privptr = netdev_priv(dev);
        struct iucv_event   ev;

        IUCV_DBF_TEXT(trace, 3, __func__);

        ev.conn = privptr->conn;

        fsm_newstate(fi, DEV_STATE_STOPWAIT);
        fsm_event(privptr->conn->fsm, CONN_EVENT_STOP, &ev);
}

/**
 * Called from connection statemachine
 * when a connection is up and running.
 *
 * @param fi    An instance of an interface statemachine.
 * @param event The event, just happened.
 * @param arg   Generic pointer, casted from struct net_device * upon call.
 */
static void
dev_action_connup(fsm_instance *fi, int event, void *arg)
{
        struct net_device   *dev = arg;
        struct netiucv_priv *privptr = netdev_priv(dev);

        IUCV_DBF_TEXT(trace, 3, __func__);

        switch (fsm_getstate(fi)) {
                case DEV_STATE_STARTWAIT:
                        fsm_newstate(fi, DEV_STATE_RUNNING);
                        dev_info(privptr->dev,
                                "The IUCV device has been connected"
                                " successfully to %s\n",
                                netiucv_printuser(privptr->conn));
                        IUCV_DBF_TEXT(setup, 3,
                                "connection is up and running\n");
                        break;
                case DEV_STATE_STOPWAIT:
                        IUCV_DBF_TEXT(data, 2,
                                "dev_action_connup: in DEV_STATE_STOPWAIT\n");
                        break;
        }
}

/**
 * Called from connection statemachine
 * when a connection has been shutdown.
 *
 * @param fi    An instance of an interface statemachine.
 * @param event The event, just happened.
 * @param arg   Generic pointer, casted from struct net_device * upon call.
 */
static void
dev_action_conndown(fsm_instance *fi, int event, void *arg)
{
        IUCV_DBF_TEXT(trace, 3, __func__);

        switch (fsm_getstate(fi)) {
                case DEV_STATE_RUNNING:
                        fsm_newstate(fi, DEV_STATE_STARTWAIT);
                        break;
                case DEV_STATE_STOPWAIT:
                        fsm_newstate(fi, DEV_STATE_STOPPED);
                        IUCV_DBF_TEXT(setup, 3, "connection is down\n");
                        break;
        }
}

static const fsm_node dev_fsm[] = {
        { DEV_STATE_STOPPED,    DEV_EVENT_START,   dev_action_start    },

        { DEV_STATE_STOPWAIT,   DEV_EVENT_START,   dev_action_start    },
        { DEV_STATE_STOPWAIT,   DEV_EVENT_CONDOWN, dev_action_conndown },

        { DEV_STATE_STARTWAIT,  DEV_EVENT_STOP,    dev_action_stop     },
        { DEV_STATE_STARTWAIT,  DEV_EVENT_CONUP,   dev_action_connup   },

        { DEV_STATE_RUNNING,    DEV_EVENT_STOP,    dev_action_stop     },
        { DEV_STATE_RUNNING,    DEV_EVENT_CONDOWN, dev_action_conndown },
        { DEV_STATE_RUNNING,    DEV_EVENT_CONUP,   netiucv_action_nop  },
};

static const int DEV_FSM_LEN = sizeof(dev_fsm) / sizeof(fsm_node);

/**
 * Transmit a packet.
 * This is a helper function for netiucv_tx().
 *
 * @param conn Connection to be used for sending.
 * @param skb Pointer to struct sk_buff of packet to send.
 *            The linklevel header has already been set up
 *            by netiucv_tx().
 *
 * @return 0 on success, -ERRNO on failure. (Never fails.)
 */
static int netiucv_transmit_skb(struct iucv_connection *conn,
                                struct sk_buff *skb)
{
        struct iucv_message msg;
        unsigned long saveflags;
        struct ll_header header;
        int rc;

        if (fsm_getstate(conn->fsm) != CONN_STATE_IDLE) {
                int l = skb->len + NETIUCV_HDRLEN;

                spin_lock_irqsave(&conn->collect_lock, saveflags);
                if (conn->collect_len + l >
                    (conn->max_buffsize - NETIUCV_HDRLEN)) {
                        rc = -EBUSY;
                        IUCV_DBF_TEXT(data, 2,
                                      "EBUSY from netiucv_transmit_skb\n");
                } else {
                        refcount_inc(&skb->users);
                        skb_queue_tail(&conn->collect_queue, skb);
                        conn->collect_len += l;
                        rc = 0;
                }
                spin_unlock_irqrestore(&conn->collect_lock, saveflags);
        } else {
                struct sk_buff *nskb = skb;
                /**
                 * Copy the skb to a new allocated skb in lowmem only if the
                 * data is located above 2G in memory or tailroom is < 2.
                 */
                unsigned long hi = ((unsigned long)(skb_tail_pointer(skb) +
                                    NETIUCV_HDRLEN)) >> 31;
                int copied = 0;
                if (hi || (skb_tailroom(skb) < 2)) {
                        nskb = alloc_skb(skb->len + NETIUCV_HDRLEN +
                                         NETIUCV_HDRLEN, GFP_ATOMIC | GFP_DMA);
                        if (!nskb) {
                                IUCV_DBF_TEXT(data, 2, "alloc_skb failed\n");
                                rc = -ENOMEM;
                                return rc;
                        } else {
                                skb_reserve(nskb, NETIUCV_HDRLEN);
                                skb_put_data(nskb, skb->data, skb->len);
                        }
                        copied = 1;
                }
                /**
                 * skb now is below 2G and has enough room. Add headers.
                 */
                header.next = nskb->len + NETIUCV_HDRLEN;
                memcpy(skb_push(nskb, NETIUCV_HDRLEN), &header, NETIUCV_HDRLEN);
                header.next = 0;
                skb_put_data(nskb, &header, NETIUCV_HDRLEN);

                fsm_newstate(conn->fsm, CONN_STATE_TX);
                conn->prof.send_stamp = jiffies;

                msg.tag = 1;
                msg.class = 0;
                rc = iucv_message_send(conn->path, &msg, 0, 0,
                                       nskb->data, nskb->len);
                conn->prof.doios_single++;
                conn->prof.txlen += skb->len;
                conn->prof.tx_pending++;
                if (conn->prof.tx_pending > conn->prof.tx_max_pending)
                        conn->prof.tx_max_pending = conn->prof.tx_pending;
                if (rc) {
                        struct netiucv_priv *privptr;
                        fsm_newstate(conn->fsm, CONN_STATE_IDLE);
                        conn->prof.tx_pending--;
                        privptr = netdev_priv(conn->netdev);
                        if (privptr)
                                privptr->stats.tx_errors++;
                        if (copied)
                                dev_kfree_skb(nskb);
                        else {
                                /**
                                 * Remove our headers. They get added
                                 * again on retransmit.
                                 */
                                skb_pull(skb, NETIUCV_HDRLEN);
                                skb_trim(skb, skb->len - NETIUCV_HDRLEN);
                        }
                        IUCV_DBF_TEXT_(data, 2, "rc %d from iucv_send\n", rc);
                } else {
                        if (copied)
                                dev_kfree_skb(skb);
                        refcount_inc(&nskb->users);
                        skb_queue_tail(&conn->commit_queue, nskb);
                }
        }

        return rc;
}

/*
 * Interface API for upper network layers
 */

/**
 * Open an interface.
 * Called from generic network layer when ifconfig up is run.
 *
 * @param dev Pointer to interface struct.
 *
 * @return 0 on success, -ERRNO on failure. (Never fails.)
 */
static int netiucv_open(struct net_device *dev)
{
        struct netiucv_priv *priv = netdev_priv(dev);

        fsm_event(priv->fsm, DEV_EVENT_START, dev);
        return 0;
}

/**
 * Close an interface.
 * Called from generic network layer when ifconfig down is run.
 *
 * @param dev Pointer to interface struct.
 *
 * @return 0 on success, -ERRNO on failure. (Never fails.)
 */
static int netiucv_close(struct net_device *dev)
{
        struct netiucv_priv *priv = netdev_priv(dev);

        fsm_event(priv->fsm, DEV_EVENT_STOP, dev);
        return 0;
}

static int netiucv_pm_prepare(struct device *dev)
{
        IUCV_DBF_TEXT(trace, 3, __func__);
        return 0;
}

static void netiucv_pm_complete(struct device *dev)
{
        IUCV_DBF_TEXT(trace, 3, __func__);
        return;
}

/**
 * netiucv_pm_freeze() - Freeze PM callback
 * @dev:        netiucv device
 *
 * close open netiucv interfaces
 */
static int netiucv_pm_freeze(struct device *dev)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);
        struct net_device *ndev = NULL;
        int rc = 0;

        IUCV_DBF_TEXT(trace, 3, __func__);
        if (priv && priv->conn)
                ndev = priv->conn->netdev;
        if (!ndev)
                goto out;
        netif_device_detach(ndev);
        priv->pm_state = fsm_getstate(priv->fsm);
        rc = netiucv_close(ndev);
out:
        return rc;
}

/**
 * netiucv_pm_restore_thaw() - Thaw and restore PM callback
 * @dev:        netiucv device
 *
 * re-open netiucv interfaces closed during freeze
 */
static int netiucv_pm_restore_thaw(struct device *dev)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);
        struct net_device *ndev = NULL;
        int rc = 0;

        IUCV_DBF_TEXT(trace, 3, __func__);
        if (priv && priv->conn)
                ndev = priv->conn->netdev;
        if (!ndev)
                goto out;
        switch (priv->pm_state) {
        case DEV_STATE_RUNNING:
        case DEV_STATE_STARTWAIT:
                rc = netiucv_open(ndev);
                break;
        default:
                break;
        }
        netif_device_attach(ndev);
out:
        return rc;
}

/**
 * Start transmission of a packet.
 * Called from generic network device layer.
 *
 * @param skb Pointer to buffer containing the packet.
 * @param dev Pointer to interface struct.
 *
 * @return 0 if packet consumed, !0 if packet rejected.
 *         Note: If we return !0, then the packet is free'd by
 *               the generic network layer.
 */
static int netiucv_tx(struct sk_buff *skb, struct net_device *dev)
{
        struct netiucv_priv *privptr = netdev_priv(dev);
        int rc;

        IUCV_DBF_TEXT(trace, 4, __func__);
        /**
         * Some sanity checks ...
         */
        if (skb == NULL) {
                IUCV_DBF_TEXT(data, 2, "netiucv_tx: skb is NULL\n");
                privptr->stats.tx_dropped++;
                return NETDEV_TX_OK;
        }
        if (skb_headroom(skb) < NETIUCV_HDRLEN) {
                IUCV_DBF_TEXT(data, 2,
                        "netiucv_tx: skb_headroom < NETIUCV_HDRLEN\n");
                dev_kfree_skb(skb);
                privptr->stats.tx_dropped++;
                return NETDEV_TX_OK;
        }

        /**
         * If connection is not running, try to restart it
         * and throw away packet.
         */
        if (fsm_getstate(privptr->fsm) != DEV_STATE_RUNNING) {
                dev_kfree_skb(skb);
                privptr->stats.tx_dropped++;
                privptr->stats.tx_errors++;
                privptr->stats.tx_carrier_errors++;
                return NETDEV_TX_OK;
        }

        if (netiucv_test_and_set_busy(dev)) {
                IUCV_DBF_TEXT(data, 2, "EBUSY from netiucv_tx\n");
                return NETDEV_TX_BUSY;
        }
        netif_trans_update(dev);
        rc = netiucv_transmit_skb(privptr->conn, skb);
        netiucv_clear_busy(dev);
        return rc ? NETDEV_TX_BUSY : NETDEV_TX_OK;
}

/**
 * netiucv_stats
 * @dev: Pointer to interface struct.
 *
 * Returns interface statistics of a device.
 *
 * Returns pointer to stats struct of this interface.
 */
static struct net_device_stats *netiucv_stats (struct net_device * dev)
{
        struct netiucv_priv *priv = netdev_priv(dev);

        IUCV_DBF_TEXT(trace, 5, __func__);
        return &priv->stats;
}

/*
 * attributes in sysfs
 */

static ssize_t user_show(struct device *dev, struct device_attribute *attr,
                         char *buf)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 5, __func__);
        return sprintf(buf, "%s\n", netiucv_printuser(priv->conn));
}

static int netiucv_check_user(const char *buf, size_t count, char *username,
                              char *userdata)
{
        const char *p;
        int i;

        p = strchr(buf, '.');
        if ((p && ((count > 26) ||
                   ((p - buf) > 8) ||
                   (buf + count - p > 18))) ||
            (!p && (count > 9))) {
                IUCV_DBF_TEXT(setup, 2, "conn_write: too long\n");
                return -EINVAL;
        }

        for (i = 0, p = buf; i < 8 && *p && *p != '.'; i++, p++) {
                if (isalnum(*p) || *p == '$') {
                        username[i] = toupper(*p);
                        continue;
                }
                if (*p == '\n')
                        /* trailing lf, grr */
                        break;
                IUCV_DBF_TEXT_(setup, 2,
                               "conn_write: invalid character %02x\n", *p);
                return -EINVAL;
        }
        while (i < 8)
                username[i++] = ' ';
        username[8] = '\0';

        if (*p == '.') {
                p++;
                for (i = 0; i < 16 && *p; i++, p++) {
                        if (*p == '\n')
                                break;
                        userdata[i] = toupper(*p);
                }
                while (i > 0 && i < 16)
                        userdata[i++] = ' ';
        } else
                memcpy(userdata, iucvMagic_ascii, 16);
        userdata[16] = '\0';
        ASCEBC(userdata, 16);

        return 0;
}

static ssize_t user_write(struct device *dev, struct device_attribute *attr,
                          const char *buf, size_t count)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);
        struct net_device *ndev = priv->conn->netdev;
        char    username[9];
        char    userdata[17];
        int     rc;
        struct iucv_connection *cp;

        IUCV_DBF_TEXT(trace, 3, __func__);
        rc = netiucv_check_user(buf, count, username, userdata);
        if (rc)
                return rc;

        if (memcmp(username, priv->conn->userid, 9) &&
            (ndev->flags & (IFF_UP | IFF_RUNNING))) {
                /* username changed while the interface is active. */
                IUCV_DBF_TEXT(setup, 2, "user_write: device active\n");
                return -EPERM;
        }
        read_lock_bh(&iucv_connection_rwlock);
        list_for_each_entry(cp, &iucv_connection_list, list) {
                if (!strncmp(username, cp->userid, 9) &&
                   !strncmp(userdata, cp->userdata, 17) && cp->netdev != ndev) {
                        read_unlock_bh(&iucv_connection_rwlock);
                        IUCV_DBF_TEXT_(setup, 2, "user_write: Connection to %s "
                                "already exists\n", netiucv_printuser(cp));
                        return -EEXIST;
                }
        }
        read_unlock_bh(&iucv_connection_rwlock);
        memcpy(priv->conn->userid, username, 9);
        memcpy(priv->conn->userdata, userdata, 17);
        return count;
}

static DEVICE_ATTR(user, 0644, user_show, user_write);

static ssize_t buffer_show (struct device *dev, struct device_attribute *attr,
                            char *buf)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 5, __func__);
        return sprintf(buf, "%d\n", priv->conn->max_buffsize);
}

static ssize_t buffer_write (struct device *dev, struct device_attribute *attr,
                             const char *buf, size_t count)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);
        struct net_device *ndev = priv->conn->netdev;
        unsigned int bs1;
        int rc;

        IUCV_DBF_TEXT(trace, 3, __func__);
        if (count >= 39)
                return -EINVAL;

        rc = kstrtouint(buf, 0, &bs1);

        if (rc == -EINVAL) {
                IUCV_DBF_TEXT_(setup, 2, "buffer_write: invalid char %s\n",
                        buf);
                return -EINVAL;
        }
        if ((rc == -ERANGE) || (bs1 > NETIUCV_BUFSIZE_MAX)) {
                IUCV_DBF_TEXT_(setup, 2,
                        "buffer_write: buffer size %d too large\n",
                        bs1);
                return -EINVAL;
        }
        if ((ndev->flags & IFF_RUNNING) &&
            (bs1 < (ndev->mtu + NETIUCV_HDRLEN + 2))) {
                IUCV_DBF_TEXT_(setup, 2,
                        "buffer_write: buffer size %d too small\n",
                        bs1);
                return -EINVAL;
        }
        if (bs1 < (576 + NETIUCV_HDRLEN + NETIUCV_HDRLEN)) {
                IUCV_DBF_TEXT_(setup, 2,
                        "buffer_write: buffer size %d too small\n",
                        bs1);
                return -EINVAL;
        }

        priv->conn->max_buffsize = bs1;
        if (!(ndev->flags & IFF_RUNNING))
                ndev->mtu = bs1 - NETIUCV_HDRLEN - NETIUCV_HDRLEN;

        return count;

}

static DEVICE_ATTR(buffer, 0644, buffer_show, buffer_write);

static ssize_t dev_fsm_show (struct device *dev, struct device_attribute *attr,
                             char *buf)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 5, __func__);
        return sprintf(buf, "%s\n", fsm_getstate_str(priv->fsm));
}

static DEVICE_ATTR(device_fsm_state, 0444, dev_fsm_show, NULL);

static ssize_t conn_fsm_show (struct device *dev,
                              struct device_attribute *attr, char *buf)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 5, __func__);
        return sprintf(buf, "%s\n", fsm_getstate_str(priv->conn->fsm));
}

static DEVICE_ATTR(connection_fsm_state, 0444, conn_fsm_show, NULL);

static ssize_t maxmulti_show (struct device *dev,
                              struct device_attribute *attr, char *buf)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 5, __func__);
        return sprintf(buf, "%ld\n", priv->conn->prof.maxmulti);
}

static ssize_t maxmulti_write (struct device *dev,
                               struct device_attribute *attr,
                               const char *buf, size_t count)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 4, __func__);
        priv->conn->prof.maxmulti = 0;
        return count;
}

static DEVICE_ATTR(max_tx_buffer_used, 0644, maxmulti_show, maxmulti_write);

static ssize_t maxcq_show (struct device *dev, struct device_attribute *attr,
                           char *buf)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 5, __func__);
        return sprintf(buf, "%ld\n", priv->conn->prof.maxcqueue);
}

static ssize_t maxcq_write (struct device *dev, struct device_attribute *attr,
                            const char *buf, size_t count)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 4, __func__);
        priv->conn->prof.maxcqueue = 0;
        return count;
}

static DEVICE_ATTR(max_chained_skbs, 0644, maxcq_show, maxcq_write);

static ssize_t sdoio_show (struct device *dev, struct device_attribute *attr,
                           char *buf)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 5, __func__);
        return sprintf(buf, "%ld\n", priv->conn->prof.doios_single);
}

static ssize_t sdoio_write (struct device *dev, struct device_attribute *attr,
                            const char *buf, size_t count)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 4, __func__);
        priv->conn->prof.doios_single = 0;
        return count;
}

static DEVICE_ATTR(tx_single_write_ops, 0644, sdoio_show, sdoio_write);

static ssize_t mdoio_show (struct device *dev, struct device_attribute *attr,
                           char *buf)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 5, __func__);
        return sprintf(buf, "%ld\n", priv->conn->prof.doios_multi);
}

static ssize_t mdoio_write (struct device *dev, struct device_attribute *attr,
                            const char *buf, size_t count)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 5, __func__);
        priv->conn->prof.doios_multi = 0;
        return count;
}

static DEVICE_ATTR(tx_multi_write_ops, 0644, mdoio_show, mdoio_write);

static ssize_t txlen_show (struct device *dev, struct device_attribute *attr,
                           char *buf)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 5, __func__);
        return sprintf(buf, "%ld\n", priv->conn->prof.txlen);
}

static ssize_t txlen_write (struct device *dev, struct device_attribute *attr,
                            const char *buf, size_t count)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 4, __func__);
        priv->conn->prof.txlen = 0;
        return count;
}

static DEVICE_ATTR(netto_bytes, 0644, txlen_show, txlen_write);

static ssize_t txtime_show (struct device *dev, struct device_attribute *attr,
                            char *buf)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 5, __func__);
        return sprintf(buf, "%ld\n", priv->conn->prof.tx_time);
}

static ssize_t txtime_write (struct device *dev, struct device_attribute *attr,
                             const char *buf, size_t count)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 4, __func__);
        priv->conn->prof.tx_time = 0;
        return count;
}

static DEVICE_ATTR(max_tx_io_time, 0644, txtime_show, txtime_write);

static ssize_t txpend_show (struct device *dev, struct device_attribute *attr,
                            char *buf)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 5, __func__);
        return sprintf(buf, "%ld\n", priv->conn->prof.tx_pending);
}

static ssize_t txpend_write (struct device *dev, struct device_attribute *attr,
                             const char *buf, size_t count)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 4, __func__);
        priv->conn->prof.tx_pending = 0;
        return count;
}

static DEVICE_ATTR(tx_pending, 0644, txpend_show, txpend_write);

static ssize_t txmpnd_show (struct device *dev, struct device_attribute *attr,
                            char *buf)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 5, __func__);
        return sprintf(buf, "%ld\n", priv->conn->prof.tx_max_pending);
}

static ssize_t txmpnd_write (struct device *dev, struct device_attribute *attr,
                             const char *buf, size_t count)
{
        struct netiucv_priv *priv = dev_get_drvdata(dev);

        IUCV_DBF_TEXT(trace, 4, __func__);
        priv->conn->prof.tx_max_pending = 0;
        return count;
}

static DEVICE_ATTR(tx_max_pending, 0644, txmpnd_show, txmpnd_write);

static struct attribute *netiucv_attrs[] = {
        &dev_attr_buffer.attr,
        &dev_attr_user.attr,
        NULL,
};

static struct attribute_group netiucv_attr_group = {
        .attrs = netiucv_attrs,
};

static struct attribute *netiucv_stat_attrs[] = {
        &dev_attr_device_fsm_state.attr,
        &dev_attr_connection_fsm_state.attr,
        &dev_attr_max_tx_buffer_used.attr,
        &dev_attr_max_chained_skbs.attr,
        &dev_attr_tx_single_write_ops.attr,
        &dev_attr_tx_multi_write_ops.attr,
        &dev_attr_netto_bytes.attr,
        &dev_attr_max_tx_io_time.attr,
        &dev_attr_tx_pending.attr,
        &dev_attr_tx_max_pending.attr,
        NULL,
};

static struct attribute_group netiucv_stat_attr_group = {
        .name  = "stats",
        .attrs = netiucv_stat_attrs,
};

static const struct attribute_group *netiucv_attr_groups[] = {
        &netiucv_stat_attr_group,
        &netiucv_attr_group,
        NULL,
};

static int netiucv_register_device(struct net_device *ndev)
{
        struct netiucv_priv *priv = netdev_priv(ndev);
        struct device *dev = kzalloc(sizeof(struct device), GFP_KERNEL);
        int ret;

        IUCV_DBF_TEXT(trace, 3, __func__);

        if (dev) {
                dev_set_name(dev, "net%s", ndev->name);
                dev->bus = &iucv_bus;
                dev->parent = iucv_root;
                dev->groups = netiucv_attr_groups;
                /*
                 * The release function could be called after the
                 * module has been unloaded. It's _only_ task is to
                 * free the struct. Therefore, we specify kfree()
                 * directly here. (Probably a little bit obfuscating
                 * but legitime ...).
                 */
                dev->release = (void (*)(struct device *))kfree;
                dev->driver = &netiucv_driver;
        } else
                return -ENOMEM;

        ret = device_register(dev);
        if (ret) {
                put_device(dev);
                return ret;
        }
        priv->dev = dev;
        dev_set_drvdata(dev, priv);
        return 0;
}

static void netiucv_unregister_device(struct device *dev)
{
        IUCV_DBF_TEXT(trace, 3, __func__);
        device_unregister(dev);
}

/**
 * Allocate and initialize a new connection structure.
 * Add it to the list of netiucv connections;
 */
static struct iucv_connection *netiucv_new_connection(struct net_device *dev,
                                                      char *username,
                                                      char *userdata)
{
        struct iucv_connection *conn;

        conn = kzalloc(sizeof(*conn), GFP_KERNEL);
        if (!conn)
                goto out;
        skb_queue_head_init(&conn->collect_queue);
        skb_queue_head_init(&conn->commit_queue);
        spin_lock_init(&conn->collect_lock);
        conn->max_buffsize = NETIUCV_BUFSIZE_DEFAULT;
        conn->netdev = dev;

        conn->rx_buff = alloc_skb(conn->max_buffsize, GFP_KERNEL | GFP_DMA);
        if (!conn->rx_buff)
                goto out_conn;
        conn->tx_buff = alloc_skb(conn->max_buffsize, GFP_KERNEL | GFP_DMA);
        if (!conn->tx_buff)
                goto out_rx;
        conn->fsm = init_fsm("netiucvconn", conn_state_names,
                             conn_event_names, NR_CONN_STATES,
                             NR_CONN_EVENTS, conn_fsm, CONN_FSM_LEN,
                             GFP_KERNEL);
        if (!conn->fsm)
                goto out_tx;

        fsm_settimer(conn->fsm, &conn->timer);
        fsm_newstate(conn->fsm, CONN_STATE_INVALID);

        if (userdata)
                memcpy(conn->userdata, userdata, 17);
        if (username) {
                memcpy(conn->userid, username, 9);
                fsm_newstate(conn->fsm, CONN_STATE_STOPPED);
        }

        write_lock_bh(&iucv_connection_rwlock);
        list_add_tail(&conn->list, &iucv_connection_list);
        write_unlock_bh(&iucv_connection_rwlock);
        return conn;

out_tx:
        kfree_skb(conn->tx_buff);
out_rx:
        kfree_skb(conn->rx_buff);
out_conn:
        kfree(conn);
out:
        return NULL;
}

/**
 * Release a connection structure and remove it from the
 * list of netiucv connections.
 */
static void netiucv_remove_connection(struct iucv_connection *conn)
{

        IUCV_DBF_TEXT(trace, 3, __func__);
        write_lock_bh(&iucv_connection_rwlock);
        list_del_init(&conn->list);
        write_unlock_bh(&iucv_connection_rwlock);
        fsm_deltimer(&conn->timer);
        netiucv_purge_skb_queue(&conn->collect_queue);
        if (conn->path) {
                iucv_path_sever(conn->path, conn->userdata);
                kfree(conn->path);
                conn->path = NULL;
        }
        netiucv_purge_skb_queue(&conn->commit_queue);
        kfree_fsm(conn->fsm);
        kfree_skb(conn->rx_buff);
        kfree_skb(conn->tx_buff);
}

/**
 * Release everything of a net device.
 */
static void netiucv_free_netdevice(struct net_device *dev)
{
        struct netiucv_priv *privptr = netdev_priv(dev);

        IUCV_DBF_TEXT(trace, 3, __func__);

        if (!dev)
                return;

        if (privptr) {
                if (privptr->conn)
                        netiucv_remove_connection(privptr->conn);
                if (privptr->fsm)
                        kfree_fsm(privptr->fsm);
                privptr->conn = NULL; privptr->fsm = NULL;
                /* privptr gets freed by free_netdev() */
        }
}

/**
 * Initialize a net device. (Called from kernel in alloc_netdev())
 */
static const struct net_device_ops netiucv_netdev_ops = {
        .ndo_open               = netiucv_open,
        .ndo_stop               = netiucv_close,
        .ndo_get_stats          = netiucv_stats,
        .ndo_start_xmit         = netiucv_tx,
};

static void netiucv_setup_netdevice(struct net_device *dev)
{
        dev->mtu                 = NETIUCV_MTU_DEFAULT;
        dev->min_mtu             = 576;
        dev->max_mtu             = NETIUCV_MTU_MAX;
        dev->needs_free_netdev   = true;
        dev->priv_destructor     = netiucv_free_netdevice;
        dev->hard_header_len     = NETIUCV_HDRLEN;
        dev->addr_len            = 0;
        dev->type                = ARPHRD_SLIP;
        dev->tx_queue_len        = NETIUCV_QUEUELEN_DEFAULT;
        dev->flags               = IFF_POINTOPOINT | IFF_NOARP;
        dev->netdev_ops          = &netiucv_netdev_ops;
}

/**
 * Allocate and initialize everything of a net device.
 */
static struct net_device *netiucv_init_netdevice(char *username, char *userdata)
{
        struct netiucv_priv *privptr;
        struct net_device *dev;

        dev = alloc_netdev(sizeof(struct netiucv_priv), "iucv%d",
                           NET_NAME_UNKNOWN, netiucv_setup_netdevice);
        if (!dev)
                return NULL;
        rtnl_lock();
        if (dev_alloc_name(dev, dev->name) < 0)
                goto out_netdev;

        privptr = netdev_priv(dev);
        privptr->fsm = init_fsm("netiucvdev", dev_state_names,
                                dev_event_names, NR_DEV_STATES, NR_DEV_EVENTS,
                                dev_fsm, DEV_FSM_LEN, GFP_KERNEL);
        if (!privptr->fsm)
                goto out_netdev;

        privptr->conn = netiucv_new_connection(dev, username, userdata);
        if (!privptr->conn) {
                IUCV_DBF_TEXT(setup, 2, "NULL from netiucv_new_connection\n");
                goto out_fsm;
        }
        fsm_newstate(privptr->fsm, DEV_STATE_STOPPED);
        return dev;

out_fsm:
        kfree_fsm(privptr->fsm);

out_netdev:
        rtnl_unlock();
        free_netdev(dev);
        return NULL;
}

static ssize_t connection_store(struct device_driver *drv, const char *buf,
                                size_t count)
{
        char username[9];
        char userdata[17];
        int rc;
        struct net_device *dev;
        struct netiucv_priv *priv;
        struct iucv_connection *cp;

        IUCV_DBF_TEXT(trace, 3, __func__);
        rc = netiucv_check_user(buf, count, username, userdata);
        if (rc)
                return rc;

        read_lock_bh(&iucv_connection_rwlock);
        list_for_each_entry(cp, &iucv_connection_list, list) {
                if (!strncmp(username, cp->userid, 9) &&
                    !strncmp(userdata, cp->userdata, 17)) {
                        read_unlock_bh(&iucv_connection_rwlock);
                        IUCV_DBF_TEXT_(setup, 2, "conn_write: Connection to %s "
                                "already exists\n", netiucv_printuser(cp));
                        return -EEXIST;
                }
        }
        read_unlock_bh(&iucv_connection_rwlock);

        dev = netiucv_init_netdevice(username, userdata);
        if (!dev) {
                IUCV_DBF_TEXT(setup, 2, "NULL from netiucv_init_netdevice\n");
                return -ENODEV;
        }

        rc = netiucv_register_device(dev);
        if (rc) {
                rtnl_unlock();
                IUCV_DBF_TEXT_(setup, 2,
                        "ret %d from netiucv_register_device\n", rc);
                goto out_free_ndev;
        }

        /* sysfs magic */
        priv = netdev_priv(dev);
        SET_NETDEV_DEV(dev, priv->dev);

        rc = register_netdevice(dev);
        rtnl_unlock();
        if (rc)
                goto out_unreg;

        dev_info(priv->dev, "The IUCV interface to %s has been established "
                            "successfully\n",
                netiucv_printuser(priv->conn));

        return count;

out_unreg:
        netiucv_unregister_device(priv->dev);
out_free_ndev:
        netiucv_free_netdevice(dev);
        return rc;
}
static DRIVER_ATTR_WO(connection);

static ssize_t remove_store(struct device_driver *drv, const char *buf,
                            size_t count)
{
        struct iucv_connection *cp;
        struct net_device *ndev;
        struct netiucv_priv *priv;
        struct device *dev;
        char name[IFNAMSIZ];
        const char *p;
        int i;

        IUCV_DBF_TEXT(trace, 3, __func__);

        if (count >= IFNAMSIZ)
                count = IFNAMSIZ - 1;

        for (i = 0, p = buf; i < count && *p; i++, p++) {
                if (*p == '\n' || *p == ' ')
                        /* trailing lf, grr */
                        break;
                name[i] = *p;
        }
        name[i] = '\0';

        read_lock_bh(&iucv_connection_rwlock);
        list_for_each_entry(cp, &iucv_connection_list, list) {
                ndev = cp->netdev;
                priv = netdev_priv(ndev);
                dev = priv->dev;
                if (strncmp(name, ndev->name, count))
                        continue;
                read_unlock_bh(&iucv_connection_rwlock);
                if (ndev->flags & (IFF_UP | IFF_RUNNING)) {
                        dev_warn(dev, "The IUCV device is connected"
                                " to %s and cannot be removed\n",
                                priv->conn->userid);
                        IUCV_DBF_TEXT(data, 2, "remove_write: still active\n");
                        return -EPERM;
                }
                unregister_netdev(ndev);
                netiucv_unregister_device(dev);
                return count;
        }
        read_unlock_bh(&iucv_connection_rwlock);
        IUCV_DBF_TEXT(data, 2, "remove_write: unknown device\n");
        return -EINVAL;
}
static DRIVER_ATTR_WO(remove);

static struct attribute * netiucv_drv_attrs[] = {
        &driver_attr_connection.attr,
        &driver_attr_remove.attr,
        NULL,
};

static struct attribute_group netiucv_drv_attr_group = {
        .attrs = netiucv_drv_attrs,
};

static const struct attribute_group *netiucv_drv_attr_groups[] = {
        &netiucv_drv_attr_group,
        NULL,
};

static void netiucv_banner(void)
{
        pr_info("driver initialized\n");
}

static void __exit netiucv_exit(void)
{
        struct iucv_connection *cp;
        struct net_device *ndev;
        struct netiucv_priv *priv;
        struct device *dev;

        IUCV_DBF_TEXT(trace, 3, __func__);
        while (!list_empty(&iucv_connection_list)) {
                cp = list_entry(iucv_connection_list.next,
                                struct iucv_connection, list);
                ndev = cp->netdev;
                priv = netdev_priv(ndev);
                dev = priv->dev;

                unregister_netdev(ndev);
                netiucv_unregister_device(dev);
        }

        device_unregister(netiucv_dev);
        driver_unregister(&netiucv_driver);
        iucv_unregister(&netiucv_handler, 1);
        iucv_unregister_dbf_views();

        pr_info("driver unloaded\n");
        return;
}

static int __init netiucv_init(void)
{
        int rc;

        rc = iucv_register_dbf_views();
        if (rc)
                goto out;
        rc = iucv_register(&netiucv_handler, 1);
        if (rc)
                goto out_dbf;
        IUCV_DBF_TEXT(trace, 3, __func__);
        netiucv_driver.groups = netiucv_drv_attr_groups;
        rc = driver_register(&netiucv_driver);
        if (rc) {
                IUCV_DBF_TEXT_(setup, 2, "ret %d from driver_register\n", rc);
                goto out_iucv;
        }
        /* establish dummy device */
        netiucv_dev = kzalloc(sizeof(struct device), GFP_KERNEL);
        if (!netiucv_dev) {
                rc = -ENOMEM;
                goto out_driver;
        }
        dev_set_name(netiucv_dev, "netiucv");
        netiucv_dev->bus = &iucv_bus;
        netiucv_dev->parent = iucv_root;
        netiucv_dev->release = (void (*)(struct device *))kfree;
        netiucv_dev->driver = &netiucv_driver;
        rc = device_register(netiucv_dev);
        if (rc) {
                put_device(netiucv_dev);
                goto out_driver;
        }
        netiucv_banner();
        return rc;

out_driver:
        driver_unregister(&netiucv_driver);
out_iucv:
        iucv_unregister(&netiucv_handler, 1);
out_dbf:
        iucv_unregister_dbf_views();
out:
        return rc;
}

module_init(netiucv_init);
module_exit(netiucv_exit);
MODULE_LICENSE("GPL");