// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright IBM Corp. 2001, 2009
 * Author(s):
 *      Original CTC driver(s):
 *              Fritz Elfert (felfert@millenux.com)
 *              Dieter Wellerdiek (wel@de.ibm.com)
 *              Martin Schwidefsky (schwidefsky@de.ibm.com)
 *              Denis Joseph Barrow (barrow_dj@yahoo.com)
 *              Jochen Roehrig (roehrig@de.ibm.com)
 *              Cornelia Huck <cornelia.huck@de.ibm.com>
 *      MPC additions:
 *              Belinda Thompson (belindat@us.ibm.com)
 *              Andy Richter (richtera@us.ibm.com)
 *      Revived by:
 *              Peter Tiedemann (ptiedem@de.ibm.com)
 */

#undef DEBUG
#undef DEBUGDATA
#undef DEBUGCCW

#define pr_fmt(fmt) "ctcm: " fmt

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

#include <linux/io.h>
#include <asm/ccwdev.h>
#include <asm/ccwgroup.h>
#include <linux/uaccess.h>

#include <asm/idals.h>

#include "ctcm_fsms.h"
#include "ctcm_main.h"

/* Some common global variables */

/*
 * The root device for ctcm group devices
 */
static struct device *ctcm_root_dev;

/*
 * Linked list of all detected channels.
 */
struct channel *channels;

/*
 * Unpack a just received skb and hand it over to
 * upper layers.
 *
 *  ch          The channel where this skb has been received.
 *  pskb        The received skb.
 */
void ctcm_unpack_skb(struct channel *ch, struct sk_buff *pskb)
{
        struct net_device *dev = ch->netdev;
        struct ctcm_priv *priv = dev->ml_priv;
        __u16 len = *((__u16 *) pskb->data);

        skb_put(pskb, 2 + LL_HEADER_LENGTH);
        skb_pull(pskb, 2);
        pskb->dev = dev;
        pskb->ip_summed = CHECKSUM_UNNECESSARY;
        while (len > 0) {
                struct sk_buff *skb;
                int skblen;
                struct ll_header *header = (struct ll_header *)pskb->data;

                skb_pull(pskb, LL_HEADER_LENGTH);
                if ((ch->protocol == CTCM_PROTO_S390) &&
                    (header->type != ETH_P_IP)) {
                        if (!(ch->logflags & LOG_FLAG_ILLEGALPKT)) {
                                ch->logflags |= LOG_FLAG_ILLEGALPKT;
                                /*
                                 * Check packet type only if we stick strictly
                                 * to S/390's protocol of OS390. This only
                                 * supports IP. Otherwise allow any packet
                                 * type.
                                 */
                                CTCM_DBF_TEXT_(ERROR, CTC_DBF_ERROR,
                                        "%s(%s): Illegal packet type 0x%04x"
                                        " - dropping",
                                        CTCM_FUNTAIL, dev->name, header->type);
                        }
                        priv->stats.rx_dropped++;
                        priv->stats.rx_frame_errors++;
                        return;
                }
                pskb->protocol = cpu_to_be16(header->type);
                if ((header->length <= LL_HEADER_LENGTH) ||
                    (len <= LL_HEADER_LENGTH)) {
                        if (!(ch->logflags & LOG_FLAG_ILLEGALSIZE)) {
                                CTCM_DBF_TEXT_(ERROR, CTC_DBF_ERROR,
                                        "%s(%s): Illegal packet size %d(%d,%d)"
                                        "- dropping",
                                        CTCM_FUNTAIL, dev->name,
                                        header->length, dev->mtu, len);
                                ch->logflags |= LOG_FLAG_ILLEGALSIZE;
                        }

                        priv->stats.rx_dropped++;
                        priv->stats.rx_length_errors++;
                        return;
                }
                header->length -= LL_HEADER_LENGTH;
                len -= LL_HEADER_LENGTH;
                if ((header->length > skb_tailroom(pskb)) ||
                    (header->length > len)) {
                        if (!(ch->logflags & LOG_FLAG_OVERRUN)) {
                                CTCM_DBF_TEXT_(ERROR, CTC_DBF_ERROR,
                                        "%s(%s): Packet size %d (overrun)"
                                        " - dropping", CTCM_FUNTAIL,
                                                dev->name, header->length);
                                ch->logflags |= LOG_FLAG_OVERRUN;
                        }

                        priv->stats.rx_dropped++;
                        priv->stats.rx_length_errors++;
                        return;
                }
                skb_put(pskb, header->length);
                skb_reset_mac_header(pskb);
                len -= header->length;
                skb = dev_alloc_skb(pskb->len);
                if (!skb) {
                        if (!(ch->logflags & LOG_FLAG_NOMEM)) {
                                CTCM_DBF_TEXT_(ERROR, CTC_DBF_ERROR,
                                        "%s(%s): MEMORY allocation error",
                                                CTCM_FUNTAIL, dev->name);
                                ch->logflags |= LOG_FLAG_NOMEM;
                        }
                        priv->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;
                skblen = skb->len;
                /*
                 * reset logflags
                 */
                ch->logflags = 0;
                priv->stats.rx_packets++;
                priv->stats.rx_bytes += skblen;
                netif_rx(skb);
                if (len > 0) {
                        skb_pull(pskb, header->length);
                        if (skb_tailroom(pskb) < LL_HEADER_LENGTH) {
                                CTCM_DBF_DEV_NAME(TRACE, dev,
                                        "Overrun in ctcm_unpack_skb");
                                ch->logflags |= LOG_FLAG_OVERRUN;
                                return;
                        }
                        skb_put(pskb, LL_HEADER_LENGTH);
                }
        }
}

/*
 * Release a specific channel in the channel list.
 *
 *  ch          Pointer to channel struct to be released.
 */
static void channel_free(struct channel *ch)
{
        CTCM_DBF_TEXT_(SETUP, CTC_DBF_INFO, "%s(%s)", CTCM_FUNTAIL, ch->id);
        ch->flags &= ~CHANNEL_FLAGS_INUSE;
        fsm_newstate(ch->fsm, CTC_STATE_IDLE);
}

/*
 * Remove a specific channel in the channel list.
 *
 *  ch          Pointer to channel struct to be released.
 */
static void channel_remove(struct channel *ch)
{
        struct channel **c = &channels;
        char chid[CTCM_ID_SIZE];
        int ok = 0;

        if (ch == NULL)
                return;
        else
                strscpy(chid, ch->id, sizeof(chid));

        channel_free(ch);
        while (*c) {
                if (*c == ch) {
                        *c = ch->next;
                        fsm_deltimer(&ch->timer);
                        if (IS_MPC(ch))
                                fsm_deltimer(&ch->sweep_timer);

                        kfree_fsm(ch->fsm);
                        clear_normalized_cda(&ch->ccw[4]);
                        if (ch->trans_skb != NULL) {
                                clear_normalized_cda(&ch->ccw[1]);
                                dev_kfree_skb_any(ch->trans_skb);
                        }
                        if (IS_MPC(ch)) {
                                tasklet_kill(&ch->ch_tasklet);
                                tasklet_kill(&ch->ch_disc_tasklet);
                                kfree(ch->discontact_th);
                        }
                        kfree(ch->ccw);
                        kfree(ch->irb);
                        kfree(ch);
                        ok = 1;
                        break;
                }
                c = &((*c)->next);
        }

        CTCM_DBF_TEXT_(SETUP, CTC_DBF_INFO, "%s(%s) %s", CTCM_FUNTAIL,
                        chid, ok ? "OK" : "failed");
}

/*
 * Get a specific channel from the channel list.
 *
 *  type        Type of channel we are interested in.
 *  id          Id of channel we are interested in.
 *  direction   Direction we want to use this channel for.
 *
 * returns Pointer to a channel or NULL if no matching channel available.
 */
static struct channel *channel_get(enum ctcm_channel_types type,
                                        char *id, int direction)
{
        struct channel *ch = channels;

        while (ch && (strncmp(ch->id, id, CTCM_ID_SIZE) || (ch->type != type)))
                ch = ch->next;
        if (!ch) {
                CTCM_DBF_TEXT_(ERROR, CTC_DBF_ERROR,
                                "%s(%d, %s, %d) not found in channel list\n",
                                CTCM_FUNTAIL, type, id, direction);
        } else {
                if (ch->flags & CHANNEL_FLAGS_INUSE)
                        ch = NULL;
                else {
                        ch->flags |= CHANNEL_FLAGS_INUSE;
                        ch->flags &= ~CHANNEL_FLAGS_RWMASK;
                        ch->flags |= (direction == CTCM_WRITE)
                            ? CHANNEL_FLAGS_WRITE : CHANNEL_FLAGS_READ;
                        fsm_newstate(ch->fsm, CTC_STATE_STOPPED);
                }
        }
        return ch;
}

static long ctcm_check_irb_error(struct ccw_device *cdev, struct irb *irb)
{
        if (!IS_ERR(irb))
                return 0;

        CTCM_DBF_TEXT_(ERROR, CTC_DBF_WARN,
                        "irb error %ld on device %s\n",
                                PTR_ERR(irb), dev_name(&cdev->dev));

        switch (PTR_ERR(irb)) {
        case -EIO:
                dev_err(&cdev->dev,
                        "An I/O-error occurred on the CTCM device\n");
                break;
        case -ETIMEDOUT:
                dev_err(&cdev->dev,
                        "An adapter hardware operation timed out\n");
                break;
        default:
                dev_err(&cdev->dev,
                        "An error occurred on the adapter hardware\n");
        }
        return PTR_ERR(irb);
}


/*
 * Check sense of a unit check.
 *
 *  ch          The channel, the sense code belongs to.
 *  sense       The sense code to inspect.
 */
static void ccw_unit_check(struct channel *ch, __u8 sense)
{
        CTCM_DBF_TEXT_(TRACE, CTC_DBF_DEBUG,
                        "%s(%s): %02x",
                                CTCM_FUNTAIL, ch->id, sense);

        if (sense & SNS0_INTERVENTION_REQ) {
                if (sense & 0x01) {
                        if (ch->sense_rc != 0x01) {
                                pr_notice(
                                        "%s: The communication peer has "
                                        "disconnected\n", ch->id);
                                ch->sense_rc = 0x01;
                        }
                        fsm_event(ch->fsm, CTC_EVENT_UC_RCRESET, ch);
                } else {
                        if (ch->sense_rc != SNS0_INTERVENTION_REQ) {
                                pr_notice(
                                        "%s: The remote operating system is "
                                        "not available\n", ch->id);
                                ch->sense_rc = SNS0_INTERVENTION_REQ;
                        }
                        fsm_event(ch->fsm, CTC_EVENT_UC_RSRESET, ch);
                }
        } else if (sense & SNS0_EQUIPMENT_CHECK) {
                if (sense & SNS0_BUS_OUT_CHECK) {
                        if (ch->sense_rc != SNS0_BUS_OUT_CHECK) {
                                CTCM_DBF_TEXT_(TRACE, CTC_DBF_WARN,
                                        "%s(%s): remote HW error %02x",
                                                CTCM_FUNTAIL, ch->id, sense);
                                ch->sense_rc = SNS0_BUS_OUT_CHECK;
                        }
                        fsm_event(ch->fsm, CTC_EVENT_UC_HWFAIL, ch);
                } else {
                        if (ch->sense_rc != SNS0_EQUIPMENT_CHECK) {
                                CTCM_DBF_TEXT_(TRACE, CTC_DBF_WARN,
                                        "%s(%s): remote read parity error %02x",
                                                CTCM_FUNTAIL, ch->id, sense);
                                ch->sense_rc = SNS0_EQUIPMENT_CHECK;
                        }
                        fsm_event(ch->fsm, CTC_EVENT_UC_RXPARITY, ch);
                }
        } else if (sense & SNS0_BUS_OUT_CHECK) {
                if (ch->sense_rc != SNS0_BUS_OUT_CHECK) {
                        CTCM_DBF_TEXT_(TRACE, CTC_DBF_WARN,
                                "%s(%s): BUS OUT error %02x",
                                        CTCM_FUNTAIL, ch->id, sense);
                        ch->sense_rc = SNS0_BUS_OUT_CHECK;
                }
                if (sense & 0x04)       /* data-streaming timeout */
                        fsm_event(ch->fsm, CTC_EVENT_UC_TXTIMEOUT, ch);
                else                    /* Data-transfer parity error */
                        fsm_event(ch->fsm, CTC_EVENT_UC_TXPARITY, ch);
        } else if (sense & SNS0_CMD_REJECT) {
                if (ch->sense_rc != SNS0_CMD_REJECT) {
                        CTCM_DBF_TEXT_(TRACE, CTC_DBF_WARN,
                                "%s(%s): Command rejected",
                                                CTCM_FUNTAIL, ch->id);
                        ch->sense_rc = SNS0_CMD_REJECT;
                }
        } else if (sense == 0) {
                CTCM_DBF_TEXT_(TRACE, CTC_DBF_WARN,
                        "%s(%s): Unit check ZERO",
                                        CTCM_FUNTAIL, ch->id);
                fsm_event(ch->fsm, CTC_EVENT_UC_ZERO, ch);
        } else {
                CTCM_DBF_TEXT_(TRACE, CTC_DBF_WARN,
                        "%s(%s): Unit check code %02x unknown",
                                        CTCM_FUNTAIL, ch->id, sense);
                fsm_event(ch->fsm, CTC_EVENT_UC_UNKNOWN, ch);
        }
}

int ctcm_ch_alloc_buffer(struct channel *ch)
{
        clear_normalized_cda(&ch->ccw[1]);
        ch->trans_skb = __dev_alloc_skb(ch->max_bufsize, GFP_ATOMIC | GFP_DMA);
        if (ch->trans_skb == NULL) {
                CTCM_DBF_TEXT_(ERROR, CTC_DBF_ERROR,
                        "%s(%s): %s trans_skb allocation error",
                        CTCM_FUNTAIL, ch->id,
                        (CHANNEL_DIRECTION(ch->flags) == CTCM_READ) ?
                                "RX" : "TX");
                return -ENOMEM;
        }

        ch->ccw[1].count = ch->max_bufsize;
        if (set_normalized_cda(&ch->ccw[1], ch->trans_skb->data)) {
                dev_kfree_skb(ch->trans_skb);
                ch->trans_skb = NULL;
                CTCM_DBF_TEXT_(ERROR, CTC_DBF_ERROR,
                        "%s(%s): %s set norm_cda failed",
                        CTCM_FUNTAIL, ch->id,
                        (CHANNEL_DIRECTION(ch->flags) == CTCM_READ) ?
                                "RX" : "TX");
                return -ENOMEM;
        }

        ch->ccw[1].count = 0;
        ch->trans_skb_data = ch->trans_skb->data;
        ch->flags &= ~CHANNEL_FLAGS_BUFSIZE_CHANGED;
        return 0;
}

/*
 * Interface API for upper network layers
 */

/*
 * Open an interface.
 * Called from generic network layer when ifconfig up is run.
 *
 *  dev         Pointer to interface struct.
 *
 * returns 0 on success, -ERRNO on failure. (Never fails.)
 */
int ctcm_open(struct net_device *dev)
{
        struct ctcm_priv *priv = dev->ml_priv;

        CTCMY_DBF_DEV_NAME(SETUP, dev, "");
        if (!IS_MPC(priv))
                fsm_event(priv->fsm,    DEV_EVENT_START, dev);
        return 0;
}

/*
 * Close an interface.
 * Called from generic network layer when ifconfig down is run.
 *
 *  dev         Pointer to interface struct.
 *
 * returns 0 on success, -ERRNO on failure. (Never fails.)
 */
int ctcm_close(struct net_device *dev)
{
        struct ctcm_priv *priv = dev->ml_priv;

        CTCMY_DBF_DEV_NAME(SETUP, dev, "");
        if (!IS_MPC(priv))
                fsm_event(priv->fsm, DEV_EVENT_STOP, dev);
        return 0;
}


/*
 * Transmit a packet.
 * This is a helper function for ctcm_tx().
 *
 *  ch          Channel to be used for sending.
 *  skb         Pointer to struct sk_buff of packet to send.
 *            The linklevel header has already been set up
 *            by ctcm_tx().
 *
 * returns 0 on success, -ERRNO on failure. (Never fails.)
 */
static int ctcm_transmit_skb(struct channel *ch, struct sk_buff *skb)
{
        unsigned long saveflags;
        struct ll_header header;
        int rc = 0;
        __u16 block_len;
        int ccw_idx;
        struct sk_buff *nskb;
        unsigned long hi;

        /* we need to acquire the lock for testing the state
         * otherwise we can have an IRQ changing the state to
         * TXIDLE after the test but before acquiring the lock.
         */
        spin_lock_irqsave(&ch->collect_lock, saveflags);
        if (fsm_getstate(ch->fsm) != CTC_STATE_TXIDLE) {
                int l = skb->len + LL_HEADER_LENGTH;

                if (ch->collect_len + l > ch->max_bufsize - 2) {
                        spin_unlock_irqrestore(&ch->collect_lock, saveflags);
                        return -EBUSY;
                } else {
                        refcount_inc(&skb->users);
                        header.length = l;
                        header.type = be16_to_cpu(skb->protocol);
                        header.unused = 0;
                        memcpy(skb_push(skb, LL_HEADER_LENGTH), &header,
                               LL_HEADER_LENGTH);
                        skb_queue_tail(&ch->collect_queue, skb);
                        ch->collect_len += l;
                }
                spin_unlock_irqrestore(&ch->collect_lock, saveflags);
                goto done;
        }
        spin_unlock_irqrestore(&ch->collect_lock, saveflags);
        /*
         * Protect skb against beeing free'd by upper
         * layers.
         */
        refcount_inc(&skb->users);
        ch->prof.txlen += skb->len;
        header.length = skb->len + LL_HEADER_LENGTH;
        header.type = be16_to_cpu(skb->protocol);
        header.unused = 0;
        memcpy(skb_push(skb, LL_HEADER_LENGTH), &header, LL_HEADER_LENGTH);
        block_len = skb->len + 2;
        *((__u16 *)skb_push(skb, 2)) = block_len;

        /*
         * IDAL support in CTCM is broken, so we have to
         * care about skb's above 2G ourselves.
         */
        hi = ((unsigned long)skb_tail_pointer(skb) + LL_HEADER_LENGTH) >> 31;
        if (hi) {
                nskb = alloc_skb(skb->len, GFP_ATOMIC | GFP_DMA);
                if (!nskb) {
                        refcount_dec(&skb->users);
                        skb_pull(skb, LL_HEADER_LENGTH + 2);
                        ctcm_clear_busy(ch->netdev);
                        return -ENOMEM;
                } else {
                        skb_put_data(nskb, skb->data, skb->len);
                        refcount_inc(&nskb->users);
                        refcount_dec(&skb->users);
                        dev_kfree_skb_irq(skb);
                        skb = nskb;
                }
        }

        ch->ccw[4].count = block_len;
        if (set_normalized_cda(&ch->ccw[4], skb->data)) {
                /*
                 * idal allocation failed, try via copying to
                 * trans_skb. trans_skb usually has a pre-allocated
                 * idal.
                 */
                if (ctcm_checkalloc_buffer(ch)) {
                        /*
                         * Remove our header. It gets added
                         * again on retransmit.
                         */
                        refcount_dec(&skb->users);
                        skb_pull(skb, LL_HEADER_LENGTH + 2);
                        ctcm_clear_busy(ch->netdev);
                        return -ENOMEM;
                }

                skb_reset_tail_pointer(ch->trans_skb);
                ch->trans_skb->len = 0;
                ch->ccw[1].count = skb->len;
                skb_copy_from_linear_data(skb,
                                skb_put(ch->trans_skb, skb->len), skb->len);
                refcount_dec(&skb->users);
                dev_kfree_skb_irq(skb);
                ccw_idx = 0;
        } else {
                skb_queue_tail(&ch->io_queue, skb);
                ccw_idx = 3;
        }
        if (do_debug_ccw)
                ctcmpc_dumpit((char *)&ch->ccw[ccw_idx],
                                        sizeof(struct ccw1) * 3);
        ch->retry = 0;
        fsm_newstate(ch->fsm, CTC_STATE_TX);
        fsm_addtimer(&ch->timer, CTCM_TIME_5_SEC, CTC_EVENT_TIMER, ch);
        spin_lock_irqsave(get_ccwdev_lock(ch->cdev), saveflags);
        ch->prof.send_stamp = jiffies;
        rc = ccw_device_start(ch->cdev, &ch->ccw[ccw_idx], 0, 0xff, 0);
        spin_unlock_irqrestore(get_ccwdev_lock(ch->cdev), saveflags);
        if (ccw_idx == 3)
                ch->prof.doios_single++;
        if (rc != 0) {
                fsm_deltimer(&ch->timer);
                ctcm_ccw_check_rc(ch, rc, "single skb TX");
                if (ccw_idx == 3)
                        skb_dequeue_tail(&ch->io_queue);
                /*
                 * Remove our header. It gets added
                 * again on retransmit.
                 */
                skb_pull(skb, LL_HEADER_LENGTH + 2);
        } else if (ccw_idx == 0) {
                struct net_device *dev = ch->netdev;
                struct ctcm_priv *priv = dev->ml_priv;
                priv->stats.tx_packets++;
                priv->stats.tx_bytes += skb->len - LL_HEADER_LENGTH;
        }
done:
        ctcm_clear_busy(ch->netdev);
        return rc;
}

static void ctcmpc_send_sweep_req(struct channel *rch)
{
        struct net_device *dev = rch->netdev;
        struct ctcm_priv *priv;
        struct mpc_group *grp;
        struct th_sweep *header;
        struct sk_buff *sweep_skb;
        struct channel *ch;
        /* int rc = 0; */

        priv = dev->ml_priv;
        grp = priv->mpcg;
        ch = priv->channel[CTCM_WRITE];

        /* sweep processing is not complete until response and request */
        /* has completed for all read channels in group                */
        if (grp->in_sweep == 0) {
                grp->in_sweep = 1;
                grp->sweep_rsp_pend_num = grp->active_channels[CTCM_READ];
                grp->sweep_req_pend_num = grp->active_channels[CTCM_READ];
        }

        sweep_skb = __dev_alloc_skb(MPC_BUFSIZE_DEFAULT, GFP_ATOMIC|GFP_DMA);

        if (sweep_skb == NULL)  {
                /* rc = -ENOMEM; */
                                goto nomem;
        }

        header = skb_put_zero(sweep_skb, TH_SWEEP_LENGTH);
        header->th.th_ch_flag   = TH_SWEEP_REQ;  /* 0x0f */
        header->sw.th_last_seq  = ch->th_seq_num;

        netif_trans_update(dev);
        skb_queue_tail(&ch->sweep_queue, sweep_skb);

        fsm_addtimer(&ch->sweep_timer, 100, CTC_EVENT_RSWEEP_TIMER, ch);

        return;

nomem:
        grp->in_sweep = 0;
        ctcm_clear_busy(dev);
        fsm_event(grp->fsm, MPCG_EVENT_INOP, dev);

        return;
}

/*
 * MPC mode version of transmit_skb
 */
static int ctcmpc_transmit_skb(struct channel *ch, struct sk_buff *skb)
{
        struct pdu *p_header;
        struct net_device *dev = ch->netdev;
        struct ctcm_priv *priv = dev->ml_priv;
        struct mpc_group *grp = priv->mpcg;
        struct th_header *header;
        struct sk_buff *nskb;
        int rc = 0;
        int ccw_idx;
        unsigned long hi;
        unsigned long saveflags = 0;    /* avoids compiler warning */

        CTCM_PR_DEBUG("Enter %s: %s, cp=%i ch=0x%p id=%s state=%s\n",
                        __func__, dev->name, smp_processor_id(), ch,
                                        ch->id, fsm_getstate_str(ch->fsm));

        if ((fsm_getstate(ch->fsm) != CTC_STATE_TXIDLE) || grp->in_sweep) {
                spin_lock_irqsave(&ch->collect_lock, saveflags);
                refcount_inc(&skb->users);

                p_header = skb_push(skb, PDU_HEADER_LENGTH);
                p_header->pdu_offset = skb->len - PDU_HEADER_LENGTH;
                p_header->pdu_proto = 0x01;
                if (be16_to_cpu(skb->protocol) == ETH_P_SNAP) {
                        p_header->pdu_flag = PDU_FIRST | PDU_CNTL;
                } else {
                        p_header->pdu_flag = PDU_FIRST;
                }
                p_header->pdu_seq = 0;

                CTCM_PR_DEBUG("%s(%s): Put on collect_q - skb len: %04x \n"
                                "pdu header and data for up to 32 bytes:\n",
                                __func__, dev->name, skb->len);
                CTCM_D3_DUMP((char *)skb->data, min_t(int, 32, skb->len));

                skb_queue_tail(&ch->collect_queue, skb);
                ch->collect_len += skb->len;

                spin_unlock_irqrestore(&ch->collect_lock, saveflags);
                goto done;
        }

        /*
         * Protect skb against beeing free'd by upper
         * layers.
         */
        refcount_inc(&skb->users);

        /*
         * IDAL support in CTCM is broken, so we have to
         * care about skb's above 2G ourselves.
         */
        hi = ((unsigned long)skb->tail + TH_HEADER_LENGTH) >> 31;
        if (hi) {
                nskb = __dev_alloc_skb(skb->len, GFP_ATOMIC | GFP_DMA);
                if (!nskb) {
                        goto nomem_exit;
                } else {
                        skb_put_data(nskb, skb->data, skb->len);
                        refcount_inc(&nskb->users);
                        refcount_dec(&skb->users);
                        dev_kfree_skb_irq(skb);
                        skb = nskb;
                }
        }

        p_header = skb_push(skb, PDU_HEADER_LENGTH);
        p_header->pdu_offset = skb->len - PDU_HEADER_LENGTH;
        p_header->pdu_proto = 0x01;
        p_header->pdu_seq = 0;
        if (be16_to_cpu(skb->protocol) == ETH_P_SNAP) {
                p_header->pdu_flag = PDU_FIRST | PDU_CNTL;
        } else {
                p_header->pdu_flag = PDU_FIRST;
        }

        if (ch->collect_len > 0) {
                spin_lock_irqsave(&ch->collect_lock, saveflags);
                skb_queue_tail(&ch->collect_queue, skb);
                ch->collect_len += skb->len;
                skb = skb_dequeue(&ch->collect_queue);
                ch->collect_len -= skb->len;
                spin_unlock_irqrestore(&ch->collect_lock, saveflags);
        }

        p_header = (struct pdu *)skb->data;
        p_header->pdu_flag |= PDU_LAST;

        ch->prof.txlen += skb->len - PDU_HEADER_LENGTH;

        /* put the TH on the packet */
        header = skb_push(skb, TH_HEADER_LENGTH);
        memset(header, 0, TH_HEADER_LENGTH);

        header->th_ch_flag = TH_HAS_PDU;  /* Normal data */
        ch->th_seq_num++;
        header->th_seq_num = ch->th_seq_num;

        CTCM_PR_DBGDATA("%s(%s) ToVTAM_th_seq= %08x\n" ,
                       __func__, dev->name, ch->th_seq_num);

        CTCM_PR_DBGDATA("%s(%s): skb len: %04x\n - pdu header and data for "
                        "up to 32 bytes sent to vtam:\n",
                                __func__, dev->name, skb->len);
        CTCM_D3_DUMP((char *)skb->data, min_t(int, 32, skb->len));

        ch->ccw[4].count = skb->len;
        if (set_normalized_cda(&ch->ccw[4], skb->data)) {
                /*
                 * idal allocation failed, try via copying to trans_skb.
                 * trans_skb usually has a pre-allocated idal.
                 */
                if (ctcm_checkalloc_buffer(ch)) {
                        /*
                         * Remove our header.
                         * It gets added again on retransmit.
                         */
                                goto nomem_exit;
                }

                skb_reset_tail_pointer(ch->trans_skb);
                ch->trans_skb->len = 0;
                ch->ccw[1].count = skb->len;
                skb_put_data(ch->trans_skb, skb->data, skb->len);
                refcount_dec(&skb->users);
                dev_kfree_skb_irq(skb);
                ccw_idx = 0;
                CTCM_PR_DBGDATA("%s(%s): trans_skb len: %04x\n"
                                "up to 32 bytes sent to vtam:\n",
                                __func__, dev->name, ch->trans_skb->len);
                CTCM_D3_DUMP((char *)ch->trans_skb->data,
                                min_t(int, 32, ch->trans_skb->len));
        } else {
                skb_queue_tail(&ch->io_queue, skb);
                ccw_idx = 3;
        }
        ch->retry = 0;
        fsm_newstate(ch->fsm, CTC_STATE_TX);
        fsm_addtimer(&ch->timer, CTCM_TIME_5_SEC, CTC_EVENT_TIMER, ch);

        if (do_debug_ccw)
                ctcmpc_dumpit((char *)&ch->ccw[ccw_idx],
                                        sizeof(struct ccw1) * 3);

        spin_lock_irqsave(get_ccwdev_lock(ch->cdev), saveflags);
        ch->prof.send_stamp = jiffies;
        rc = ccw_device_start(ch->cdev, &ch->ccw[ccw_idx], 0, 0xff, 0);
        spin_unlock_irqrestore(get_ccwdev_lock(ch->cdev), saveflags);
        if (ccw_idx == 3)
                ch->prof.doios_single++;
        if (rc != 0) {
                fsm_deltimer(&ch->timer);
                ctcm_ccw_check_rc(ch, rc, "single skb TX");
                if (ccw_idx == 3)
                        skb_dequeue_tail(&ch->io_queue);
        } else if (ccw_idx == 0) {
                priv->stats.tx_packets++;
                priv->stats.tx_bytes += skb->len - TH_HEADER_LENGTH;
        }
        if (ch->th_seq_num > 0xf0000000)        /* Chose at random. */
                ctcmpc_send_sweep_req(ch);

        goto done;
nomem_exit:
        CTCM_DBF_TEXT_(MPC_ERROR, CTC_DBF_CRIT,
                        "%s(%s): MEMORY allocation ERROR\n",
                        CTCM_FUNTAIL, ch->id);
        rc = -ENOMEM;
        refcount_dec(&skb->users);
        dev_kfree_skb_any(skb);
        fsm_event(priv->mpcg->fsm, MPCG_EVENT_INOP, dev);
done:
        CTCM_PR_DEBUG("Exit %s(%s)\n", __func__, dev->name);
        return rc;
}

/*
 * Start transmission of a packet.
 * Called from generic network device layer.
 */
/* first merge version - leaving both functions separated */
static netdev_tx_t ctcm_tx(struct sk_buff *skb, struct net_device *dev)
{
        struct ctcm_priv *priv = dev->ml_priv;

        if (skb == NULL) {
                CTCM_DBF_TEXT_(ERROR, CTC_DBF_ERROR,
                                "%s(%s): NULL sk_buff passed",
                                        CTCM_FUNTAIL, dev->name);
                priv->stats.tx_dropped++;
                return NETDEV_TX_OK;
        }
        if (skb_headroom(skb) < (LL_HEADER_LENGTH + 2)) {
                CTCM_DBF_TEXT_(ERROR, CTC_DBF_ERROR,
                        "%s(%s): Got sk_buff with head room < %ld bytes",
                        CTCM_FUNTAIL, dev->name, LL_HEADER_LENGTH + 2);
                dev_kfree_skb(skb);
                priv->stats.tx_dropped++;
                return NETDEV_TX_OK;
        }

        /*
         * If channels are not running, try to restart them
         * and throw away packet.
         */
        if (fsm_getstate(priv->fsm) != DEV_STATE_RUNNING) {
                fsm_event(priv->fsm, DEV_EVENT_START, dev);
                dev_kfree_skb(skb);
                priv->stats.tx_dropped++;
                priv->stats.tx_errors++;
                priv->stats.tx_carrier_errors++;
                return NETDEV_TX_OK;
        }

        if (ctcm_test_and_set_busy(dev))
                return NETDEV_TX_BUSY;

        netif_trans_update(dev);
        if (ctcm_transmit_skb(priv->channel[CTCM_WRITE], skb) != 0)
                return NETDEV_TX_BUSY;
        return NETDEV_TX_OK;
}

/* unmerged MPC variant of ctcm_tx */
static netdev_tx_t ctcmpc_tx(struct sk_buff *skb, struct net_device *dev)
{
        int len = 0;
        struct ctcm_priv *priv = dev->ml_priv;
        struct mpc_group *grp  = priv->mpcg;
        struct sk_buff *newskb = NULL;

        /*
         * Some sanity checks ...
         */
        if (skb == NULL) {
                CTCM_DBF_TEXT_(MPC_ERROR, CTC_DBF_ERROR,
                        "%s(%s): NULL sk_buff passed",
                                        CTCM_FUNTAIL, dev->name);
                priv->stats.tx_dropped++;
                goto done;
        }
        if (skb_headroom(skb) < (TH_HEADER_LENGTH + PDU_HEADER_LENGTH)) {
                CTCM_DBF_TEXT_(MPC_TRACE, CTC_DBF_ERROR,
                        "%s(%s): Got sk_buff with head room < %ld bytes",
                        CTCM_FUNTAIL, dev->name,
                                TH_HEADER_LENGTH + PDU_HEADER_LENGTH);

                CTCM_D3_DUMP((char *)skb->data, min_t(int, 32, skb->len));

                len =  skb->len + TH_HEADER_LENGTH + PDU_HEADER_LENGTH;
                newskb = __dev_alloc_skb(len, GFP_ATOMIC | GFP_DMA);

                if (!newskb) {
                        CTCM_DBF_TEXT_(MPC_TRACE, CTC_DBF_ERROR,
                                "%s: %s: __dev_alloc_skb failed",
                                                __func__, dev->name);

                        dev_kfree_skb_any(skb);
                        priv->stats.tx_dropped++;
                        priv->stats.tx_errors++;
                        priv->stats.tx_carrier_errors++;
                        fsm_event(grp->fsm, MPCG_EVENT_INOP, dev);
                        goto done;
                }
                newskb->protocol = skb->protocol;
                skb_reserve(newskb, TH_HEADER_LENGTH + PDU_HEADER_LENGTH);
                skb_put_data(newskb, skb->data, skb->len);
                dev_kfree_skb_any(skb);
                skb = newskb;
        }

        /*
         * If channels are not running,
         * notify anybody about a link failure and throw
         * away packet.
         */
        if ((fsm_getstate(priv->fsm) != DEV_STATE_RUNNING) ||
           (fsm_getstate(grp->fsm) <  MPCG_STATE_XID2INITW)) {
                dev_kfree_skb_any(skb);
                CTCM_DBF_TEXT_(MPC_ERROR, CTC_DBF_ERROR,
                        "%s(%s): inactive MPCGROUP - dropped",
                                        CTCM_FUNTAIL, dev->name);
                priv->stats.tx_dropped++;
                priv->stats.tx_errors++;
                priv->stats.tx_carrier_errors++;
                goto done;
        }

        if (ctcm_test_and_set_busy(dev)) {
                CTCM_DBF_TEXT_(MPC_ERROR, CTC_DBF_ERROR,
                        "%s(%s): device busy - dropped",
                                        CTCM_FUNTAIL, dev->name);
                dev_kfree_skb_any(skb);
                priv->stats.tx_dropped++;
                priv->stats.tx_errors++;
                priv->stats.tx_carrier_errors++;
                fsm_event(grp->fsm, MPCG_EVENT_INOP, dev);
                goto done;
        }

        netif_trans_update(dev);
        if (ctcmpc_transmit_skb(priv->channel[CTCM_WRITE], skb) != 0) {
                CTCM_DBF_TEXT_(MPC_ERROR, CTC_DBF_ERROR,
                        "%s(%s): device error - dropped",
                                        CTCM_FUNTAIL, dev->name);
                dev_kfree_skb_any(skb);
                priv->stats.tx_dropped++;
                priv->stats.tx_errors++;
                priv->stats.tx_carrier_errors++;
                ctcm_clear_busy(dev);
                fsm_event(grp->fsm, MPCG_EVENT_INOP, dev);
                goto done;
        }
        ctcm_clear_busy(dev);
done:
        if (do_debug)
                MPC_DBF_DEV_NAME(TRACE, dev, "exit");

        return NETDEV_TX_OK;    /* handle freeing of skb here */
}


/*
 * Sets MTU of an interface.
 *
 *  dev         Pointer to interface struct.
 *  new_mtu     The new MTU to use for this interface.
 *
 * returns 0 on success, -EINVAL if MTU is out of valid range.
 *         (valid range is 576 .. 65527). If VM is on the
 *         remote side, maximum MTU is 32760, however this is
 *         not checked here.
 */
static int ctcm_change_mtu(struct net_device *dev, int new_mtu)
{
        struct ctcm_priv *priv;
        int max_bufsize;

        priv = dev->ml_priv;
        max_bufsize = priv->channel[CTCM_READ]->max_bufsize;

        if (IS_MPC(priv)) {
                if (new_mtu > max_bufsize - TH_HEADER_LENGTH)
                        return -EINVAL;
                dev->hard_header_len = TH_HEADER_LENGTH + PDU_HEADER_LENGTH;
        } else {
                if (new_mtu > max_bufsize - LL_HEADER_LENGTH - 2)
                        return -EINVAL;
                dev->hard_header_len = LL_HEADER_LENGTH + 2;
        }
        WRITE_ONCE(dev->mtu, new_mtu);
        return 0;
}

/*
 * Returns interface statistics of a device.
 *
 *  dev         Pointer to interface struct.
 *
 * returns Pointer to stats struct of this interface.
 */
static struct net_device_stats *ctcm_stats(struct net_device *dev)
{
        return &((struct ctcm_priv *)dev->ml_priv)->stats;
}

static void ctcm_free_netdevice(struct net_device *dev)
{
        struct ctcm_priv *priv;
        struct mpc_group *grp;

        CTCM_DBF_TEXT_(SETUP, CTC_DBF_INFO,
                        "%s(%s)", CTCM_FUNTAIL, dev->name);
        priv = dev->ml_priv;
        if (priv) {
                grp = priv->mpcg;
                if (grp) {
                        if (grp->fsm)
                                kfree_fsm(grp->fsm);
                        dev_kfree_skb(grp->xid_skb);
                        dev_kfree_skb(grp->rcvd_xid_skb);
                        tasklet_kill(&grp->mpc_tasklet2);
                        kfree(grp);
                        priv->mpcg = NULL;
                }
                if (priv->fsm) {
                        kfree_fsm(priv->fsm);
                        priv->fsm = NULL;
                }
                kfree(priv->xid);
                priv->xid = NULL;
        /*
         * Note: kfree(priv); is done in "opposite" function of
         * allocator function probe_device which is remove_device.
         */
        }
#ifdef MODULE
        free_netdev(dev);
#endif
}

struct mpc_group *ctcmpc_init_mpc_group(struct ctcm_priv *priv);

static const struct net_device_ops ctcm_netdev_ops = {
        .ndo_open               = ctcm_open,
        .ndo_stop               = ctcm_close,
        .ndo_get_stats          = ctcm_stats,
        .ndo_change_mtu         = ctcm_change_mtu,
        .ndo_start_xmit         = ctcm_tx,
};

static const struct net_device_ops ctcm_mpc_netdev_ops = {
        .ndo_open               = ctcm_open,
        .ndo_stop               = ctcm_close,
        .ndo_get_stats          = ctcm_stats,
        .ndo_change_mtu         = ctcm_change_mtu,
        .ndo_start_xmit         = ctcmpc_tx,
};

static void ctcm_dev_setup(struct net_device *dev)
{
        dev->type = ARPHRD_SLIP;
        dev->tx_queue_len = 100;
        dev->flags = IFF_POINTOPOINT | IFF_NOARP;
        dev->min_mtu = 576;
        dev->max_mtu = 65527;
}

/*
 * Initialize everything of the net device except the name and the
 * channel structs.
 */
static struct net_device *ctcm_init_netdevice(struct ctcm_priv *priv)
{
        struct net_device *dev;
        struct mpc_group *grp;
        if (!priv)
                return NULL;

        if (IS_MPC(priv))
                dev = alloc_netdev(0, MPC_DEVICE_GENE, NET_NAME_UNKNOWN,
                                   ctcm_dev_setup);
        else
                dev = alloc_netdev(0, CTC_DEVICE_GENE, NET_NAME_UNKNOWN,
                                   ctcm_dev_setup);

        if (!dev) {
                CTCM_DBF_TEXT_(ERROR, CTC_DBF_CRIT,
                        "%s: MEMORY allocation ERROR",
                        CTCM_FUNTAIL);
                return NULL;
        }
        dev->ml_priv = priv;
        priv->fsm = init_fsm("ctcmdev", dev_state_names, dev_event_names,
                                CTCM_NR_DEV_STATES, CTCM_NR_DEV_EVENTS,
                                dev_fsm, dev_fsm_len, GFP_KERNEL);
        if (priv->fsm == NULL) {
                CTCMY_DBF_DEV(SETUP, dev, "init_fsm error");
                free_netdev(dev);
                return NULL;
        }
        fsm_newstate(priv->fsm, DEV_STATE_STOPPED);
        fsm_settimer(priv->fsm, &priv->restart_timer);

        if (IS_MPC(priv)) {
                /*  MPC Group Initializations  */
                grp = ctcmpc_init_mpc_group(priv);
                if (grp == NULL) {
                        MPC_DBF_DEV(SETUP, dev, "init_mpc_group error");
                        free_netdev(dev);
                        return NULL;
                }
                tasklet_init(&grp->mpc_tasklet2,
                                mpc_group_ready, (unsigned long)dev);
                dev->mtu = MPC_BUFSIZE_DEFAULT -
                                TH_HEADER_LENGTH - PDU_HEADER_LENGTH;

                dev->netdev_ops = &ctcm_mpc_netdev_ops;
                dev->hard_header_len = TH_HEADER_LENGTH + PDU_HEADER_LENGTH;
                priv->buffer_size = MPC_BUFSIZE_DEFAULT;
        } else {
                dev->mtu = CTCM_BUFSIZE_DEFAULT - LL_HEADER_LENGTH - 2;
                dev->netdev_ops = &ctcm_netdev_ops;
                dev->hard_header_len = LL_HEADER_LENGTH + 2;
        }

        CTCMY_DBF_DEV(SETUP, dev, "finished");

        return dev;
}

/*
 * Main IRQ handler.
 *
 *  cdev        The ccw_device the interrupt is for.
 *  intparm     interruption parameter.
 *  irb         interruption response block.
 */
static void ctcm_irq_handler(struct ccw_device *cdev,
                                unsigned long intparm, struct irb *irb)
{
        struct channel          *ch;
        struct net_device       *dev;
        struct ctcm_priv        *priv;
        struct ccwgroup_device  *cgdev;
        int cstat;
        int dstat;

        CTCM_DBF_TEXT_(TRACE, CTC_DBF_DEBUG,
                "Enter %s(%s)", CTCM_FUNTAIL, dev_name(&cdev->dev));

        if (ctcm_check_irb_error(cdev, irb))
                return;

        cgdev = dev_get_drvdata(&cdev->dev);

        cstat = irb->scsw.cmd.cstat;
        dstat = irb->scsw.cmd.dstat;

        /* Check for unsolicited interrupts. */
        if (cgdev == NULL) {
                CTCM_DBF_TEXT_(TRACE, CTC_DBF_ERROR,
                        "%s(%s) unsolicited irq: c-%02x d-%02x\n",
                        CTCM_FUNTAIL, dev_name(&cdev->dev), cstat, dstat);
                dev_warn(&cdev->dev,
                        "The adapter received a non-specific IRQ\n");
                return;
        }

        priv = dev_get_drvdata(&cgdev->dev);

        /* Try to extract channel from driver data. */
        if (priv->channel[CTCM_READ]->cdev == cdev)
                ch = priv->channel[CTCM_READ];
        else if (priv->channel[CTCM_WRITE]->cdev == cdev)
                ch = priv->channel[CTCM_WRITE];
        else {
                dev_err(&cdev->dev,
                        "%s: Internal error: Can't determine channel for "
                        "interrupt device %s\n",
                        __func__, dev_name(&cdev->dev));
                        /* Explain: inconsistent internal structures */
                return;
        }

        dev = ch->netdev;
        if (dev == NULL) {
                dev_err(&cdev->dev,
                        "%s Internal error: net_device is NULL, ch = 0x%p\n",
                        __func__, ch);
                        /* Explain: inconsistent internal structures */
                return;
        }

        /* Copy interruption response block. */
        memcpy(ch->irb, irb, sizeof(struct irb));

        /* Issue error message and return on subchannel error code */
        if (irb->scsw.cmd.cstat) {
                fsm_event(ch->fsm, CTC_EVENT_SC_UNKNOWN, ch);
                CTCM_DBF_TEXT_(TRACE, CTC_DBF_WARN,
                        "%s(%s): sub-ch check %s: cs=%02x ds=%02x",
                                CTCM_FUNTAIL, dev->name, ch->id, cstat, dstat);
                dev_warn(&cdev->dev,
                                "A check occurred on the subchannel\n");
                return;
        }

        /* Check the reason-code of a unit check */
        if (irb->scsw.cmd.dstat & DEV_STAT_UNIT_CHECK) {
                if ((irb->ecw[0] & ch->sense_rc) == 0)
                        /* print it only once */
                        CTCM_DBF_TEXT_(TRACE, CTC_DBF_WARN,
                                "%s(%s): sense=%02x, ds=%02x",
                                CTCM_FUNTAIL, ch->id, irb->ecw[0], dstat);
                ccw_unit_check(ch, irb->ecw[0]);
                return;
        }
        if (irb->scsw.cmd.dstat & DEV_STAT_BUSY) {
                if (irb->scsw.cmd.dstat & DEV_STAT_ATTENTION)
                        fsm_event(ch->fsm, CTC_EVENT_ATTNBUSY, ch);
                else
                        fsm_event(ch->fsm, CTC_EVENT_BUSY, ch);
                return;
        }
        if (irb->scsw.cmd.dstat & DEV_STAT_ATTENTION) {
                fsm_event(ch->fsm, CTC_EVENT_ATTN, ch);
                return;
        }
        if ((irb->scsw.cmd.stctl & SCSW_STCTL_SEC_STATUS) ||
            (irb->scsw.cmd.stctl == SCSW_STCTL_STATUS_PEND) ||
            (irb->scsw.cmd.stctl ==
             (SCSW_STCTL_ALERT_STATUS | SCSW_STCTL_STATUS_PEND)))
                fsm_event(ch->fsm, CTC_EVENT_FINSTAT, ch);
        else
                fsm_event(ch->fsm, CTC_EVENT_IRQ, ch);

}

static const struct device_type ctcm_devtype = {
        .name = "ctcm",
        .groups = ctcm_attr_groups,
};

/*
 * Add ctcm specific attributes.
 * Add ctcm private data.
 *
 *  cgdev       pointer to ccwgroup_device just added
 *
 * returns 0 on success, !0 on failure.
 */
static int ctcm_probe_device(struct ccwgroup_device *cgdev)
{
        struct ctcm_priv *priv;

        CTCM_DBF_TEXT_(SETUP, CTC_DBF_INFO,
                        "%s %p",
                        __func__, cgdev);

        if (!get_device(&cgdev->dev))
                return -ENODEV;

        priv = kzalloc_obj(struct ctcm_priv);
        if (!priv) {
                CTCM_DBF_TEXT_(ERROR, CTC_DBF_ERROR,
                        "%s: memory allocation failure",
                        CTCM_FUNTAIL);
                put_device(&cgdev->dev);
                return -ENOMEM;
        }
        priv->buffer_size = CTCM_BUFSIZE_DEFAULT;
        cgdev->cdev[0]->handler = ctcm_irq_handler;
        cgdev->cdev[1]->handler = ctcm_irq_handler;
        dev_set_drvdata(&cgdev->dev, priv);
        cgdev->dev.type = &ctcm_devtype;

        return 0;
}

/*
 * Add a new channel to the list of channels.
 * Keeps the channel list sorted.
 *
 *  cdev        The ccw_device to be added.
 *  type        The type class of the new channel.
 *  priv        Points to the private data of the ccwgroup_device.
 *
 * returns 0 on success, !0 on error.
 */
static int add_channel(struct ccw_device *cdev, enum ctcm_channel_types type,
                                struct ctcm_priv *priv)
{
        struct channel **c = &channels;
        struct channel *ch;
        int ccw_num;
        int rc = 0;

        CTCM_DBF_TEXT_(SETUP, CTC_DBF_INFO,
                "%s(%s), type %d, proto %d",
                        __func__, dev_name(&cdev->dev), type, priv->protocol);

        ch = kzalloc_obj(struct channel);
        if (ch == NULL)
                return -ENOMEM;

        ch->protocol = priv->protocol;
        if (IS_MPC(priv)) {
                ch->discontact_th = kzalloc(TH_HEADER_LENGTH, GFP_KERNEL);
                if (ch->discontact_th == NULL)
                                        goto nomem_return;

                ch->discontact_th->th_blk_flag = TH_DISCONTACT;
                tasklet_init(&ch->ch_disc_tasklet,
                        mpc_action_send_discontact, (unsigned long)ch);

                tasklet_init(&ch->ch_tasklet, ctcmpc_bh, (unsigned long)ch);
                ch->max_bufsize = (MPC_BUFSIZE_DEFAULT - 35);
                ccw_num = 17;
        } else
                ccw_num = 8;

        ch->ccw = kzalloc_objs(struct ccw1, ccw_num, GFP_KERNEL | GFP_DMA);
        if (ch->ccw == NULL)
                                        goto nomem_return;

        ch->cdev = cdev;
        scnprintf(ch->id, CTCM_ID_SIZE, "ch-%s", dev_name(&cdev->dev));
        ch->type = type;

        /*
         * "static" ccws are used in the following way:
         *
         * ccw[0..2] (Channel program for generic I/O):
         *           0: prepare
         *           1: read or write (depending on direction) with fixed
         *              buffer (idal allocated once when buffer is allocated)
         *           2: nop
         * ccw[3..5] (Channel program for direct write of packets)
         *           3: prepare
         *           4: write (idal allocated on every write).
         *           5: nop
         * ccw[6..7] (Channel program for initial channel setup):
         *           6: set extended mode
         *           7: nop
         *
         * ch->ccw[0..5] are initialized in ch_action_start because
         * the channel's direction is yet unknown here.
         *
         * ccws used for xid2 negotiations
         *  ch-ccw[8-14] need to be used for the XID exchange either
         *    X side XID2 Processing
         *       8:  write control
         *       9:  write th
         *           10: write XID
         *           11: read th from secondary
         *           12: read XID   from secondary
         *           13: read 4 byte ID
         *           14: nop
         *    Y side XID Processing
         *           8:  sense
         *       9:  read th
         *           10: read XID
         *           11: write th
         *           12: write XID
         *           13: write 4 byte ID
         *           14: nop
         *
         *  ccws used for double noop due to VM timing issues
         *  which result in unrecoverable Busy on channel
         *       15: nop
         *       16: nop
         */
        ch->ccw[6].cmd_code     = CCW_CMD_SET_EXTENDED;
        ch->ccw[6].flags        = CCW_FLAG_SLI;

        ch->ccw[7].cmd_code     = CCW_CMD_NOOP;
        ch->ccw[7].flags        = CCW_FLAG_SLI;

        if (IS_MPC(priv)) {
                ch->ccw[15].cmd_code = CCW_CMD_WRITE;
                ch->ccw[15].flags    = CCW_FLAG_SLI | CCW_FLAG_CC;
                ch->ccw[15].count    = TH_HEADER_LENGTH;
                ch->ccw[15].cda      = virt_to_dma32(ch->discontact_th);

                ch->ccw[16].cmd_code = CCW_CMD_NOOP;
                ch->ccw[16].flags    = CCW_FLAG_SLI;

                ch->fsm = init_fsm(ch->id, ctc_ch_state_names,
                                ctc_ch_event_names, CTC_MPC_NR_STATES,
                                CTC_MPC_NR_EVENTS, ctcmpc_ch_fsm,
                                mpc_ch_fsm_len, GFP_KERNEL);
        } else {
                ch->fsm = init_fsm(ch->id, ctc_ch_state_names,
                                ctc_ch_event_names, CTC_NR_STATES,
                                CTC_NR_EVENTS, ch_fsm,
                                ch_fsm_len, GFP_KERNEL);
        }
        if (ch->fsm == NULL)
                                goto nomem_return;

        fsm_newstate(ch->fsm, CTC_STATE_IDLE);

        ch->irb = kzalloc_obj(struct irb);
        if (ch->irb == NULL)
                                goto nomem_return;

        while (*c && ctcm_less_than((*c)->id, ch->id))
                c = &(*c)->next;

        if (*c && (!strncmp((*c)->id, ch->id, CTCM_ID_SIZE))) {
                CTCM_DBF_TEXT_(SETUP, CTC_DBF_INFO,
                                "%s (%s) already in list, using old entry",
                                __func__, (*c)->id);

                goto free_return;
        }

        spin_lock_init(&ch->collect_lock);

        fsm_settimer(ch->fsm, &ch->timer);
        skb_queue_head_init(&ch->io_queue);
        skb_queue_head_init(&ch->collect_queue);

        if (IS_MPC(priv)) {
                fsm_settimer(ch->fsm, &ch->sweep_timer);
                skb_queue_head_init(&ch->sweep_queue);
        }
        ch->next = *c;
        *c = ch;
        return 0;

nomem_return:
        rc = -ENOMEM;

free_return:    /* note that all channel pointers are 0 or valid */
        kfree(ch->ccw);
        kfree(ch->discontact_th);
        kfree_fsm(ch->fsm);
        kfree(ch->irb);
        kfree(ch);
        return rc;
}

/*
 * Return type of a detected device.
 */
static enum ctcm_channel_types get_channel_type(struct ccw_device_id *id)
{
        enum ctcm_channel_types type;
        type = (enum ctcm_channel_types)id->driver_info;

        if (type == ctcm_channel_type_ficon)
                type = ctcm_channel_type_escon;

        return type;
}

/*
 *
 * Setup an interface.
 *
 *  cgdev       Device to be setup.
 *
 * returns 0 on success, !0 on failure.
 */
static int ctcm_new_device(struct ccwgroup_device *cgdev)
{
        char read_id[CTCM_ID_SIZE];
        char write_id[CTCM_ID_SIZE];
        int direction;
        enum ctcm_channel_types type;
        struct ctcm_priv *priv;
        struct net_device *dev;
        struct ccw_device *cdev0;
        struct ccw_device *cdev1;
        struct channel *readc;
        struct channel *writec;
        int ret;
        int result;

        priv = dev_get_drvdata(&cgdev->dev);
        if (!priv) {
                result = -ENODEV;
                goto out_err_result;
        }

        cdev0 = cgdev->cdev[0];
        cdev1 = cgdev->cdev[1];

        type = get_channel_type(&cdev0->id);

        scnprintf(read_id, CTCM_ID_SIZE, "ch-%s", dev_name(&cdev0->dev));
        scnprintf(write_id, CTCM_ID_SIZE, "ch-%s", dev_name(&cdev1->dev));

        ret = add_channel(cdev0, type, priv);
        if (ret) {
                result = ret;
                goto out_err_result;
        }
        ret = add_channel(cdev1, type, priv);
        if (ret) {
                result = ret;
                goto out_remove_channel1;
        }

        ret = ccw_device_set_online(cdev0);
        if (ret != 0) {
                CTCM_DBF_TEXT_(TRACE, CTC_DBF_NOTICE,
                        "%s(%s) set_online rc=%d",
                                CTCM_FUNTAIL, read_id, ret);
                result = -EIO;
                goto out_remove_channel2;
        }

        ret = ccw_device_set_online(cdev1);
        if (ret != 0) {
                CTCM_DBF_TEXT_(TRACE, CTC_DBF_NOTICE,
                        "%s(%s) set_online rc=%d",
                                CTCM_FUNTAIL, write_id, ret);

                result = -EIO;
                goto out_ccw1;
        }

        dev = ctcm_init_netdevice(priv);
        if (dev == NULL) {
                result = -ENODEV;
                goto out_ccw2;
        }

        for (direction = CTCM_READ; direction <= CTCM_WRITE; direction++) {
                priv->channel[direction] =
                        channel_get(type, direction == CTCM_READ ?
                                read_id : write_id, direction);
                if (priv->channel[direction] == NULL) {
                        if (direction == CTCM_WRITE)
                                channel_free(priv->channel[CTCM_READ]);
                        result = -ENODEV;
                        goto out_dev;
                }
                priv->channel[direction]->netdev = dev;
                priv->channel[direction]->protocol = priv->protocol;
                priv->channel[direction]->max_bufsize = priv->buffer_size;
        }
        /* sysfs magic */
        SET_NETDEV_DEV(dev, &cgdev->dev);

        if (register_netdev(dev)) {
                result = -ENODEV;
                goto out_dev;
        }

        strscpy(priv->fsm->name, dev->name, sizeof(priv->fsm->name));

        dev_info(&dev->dev,
                "setup OK : r/w = %s/%s, protocol : %d\n",
                        priv->channel[CTCM_READ]->id,
                        priv->channel[CTCM_WRITE]->id, priv->protocol);

        CTCM_DBF_TEXT_(SETUP, CTC_DBF_INFO,
                "setup(%s) OK : r/w = %s/%s, protocol : %d", dev->name,
                        priv->channel[CTCM_READ]->id,
                        priv->channel[CTCM_WRITE]->id, priv->protocol);

        return 0;
out_dev:
        ctcm_free_netdevice(dev);
out_ccw2:
        ccw_device_set_offline(cgdev->cdev[1]);
out_ccw1:
        ccw_device_set_offline(cgdev->cdev[0]);
out_remove_channel2:
        readc = channel_get(type, read_id, CTCM_READ);
        channel_remove(readc);
out_remove_channel1:
        writec = channel_get(type, write_id, CTCM_WRITE);
        channel_remove(writec);
out_err_result:
        return result;
}

/*
 * Shutdown an interface.
 *
 *  cgdev       Device to be shut down.
 *
 * returns 0 on success, !0 on failure.
 */
static int ctcm_shutdown_device(struct ccwgroup_device *cgdev)
{
        struct ctcm_priv *priv;
        struct net_device *dev;

        priv = dev_get_drvdata(&cgdev->dev);
        if (!priv)
                return -ENODEV;

        if (priv->channel[CTCM_READ]) {
                dev = priv->channel[CTCM_READ]->netdev;
                CTCM_DBF_DEV(SETUP, dev, "");
                /* Close the device */
                ctcm_close(dev);
                dev->flags &= ~IFF_RUNNING;
                channel_free(priv->channel[CTCM_READ]);
        } else
                dev = NULL;

        if (priv->channel[CTCM_WRITE])
                channel_free(priv->channel[CTCM_WRITE]);

        if (dev) {
                unregister_netdev(dev);
                ctcm_free_netdevice(dev);
        }

        if (priv->fsm)
                kfree_fsm(priv->fsm);

        ccw_device_set_offline(cgdev->cdev[1]);
        ccw_device_set_offline(cgdev->cdev[0]);
        channel_remove(priv->channel[CTCM_READ]);
        channel_remove(priv->channel[CTCM_WRITE]);
        priv->channel[CTCM_READ] = priv->channel[CTCM_WRITE] = NULL;

        return 0;

}


static void ctcm_remove_device(struct ccwgroup_device *cgdev)
{
        struct ctcm_priv *priv = dev_get_drvdata(&cgdev->dev);

        CTCM_DBF_TEXT_(SETUP, CTC_DBF_INFO,
                        "removing device %p, proto : %d",
                        cgdev, priv->protocol);

        if (cgdev->state == CCWGROUP_ONLINE)
                ctcm_shutdown_device(cgdev);
        dev_set_drvdata(&cgdev->dev, NULL);
        kfree(priv);
        put_device(&cgdev->dev);
}

static struct ccw_device_id ctcm_ids[] = {
        {CCW_DEVICE(0x3088, 0x08), .driver_info = ctcm_channel_type_parallel},
        {CCW_DEVICE(0x3088, 0x1e), .driver_info = ctcm_channel_type_ficon},
        {CCW_DEVICE(0x3088, 0x1f), .driver_info = ctcm_channel_type_escon},
        {},
};
MODULE_DEVICE_TABLE(ccw, ctcm_ids);

static struct ccw_driver ctcm_ccw_driver = {
        .driver = {
                .owner  = THIS_MODULE,
                .name   = "ctcm",
        },
        .ids    = ctcm_ids,
        .probe  = ccwgroup_probe_ccwdev,
        .remove = ccwgroup_remove_ccwdev,
        .int_class = IRQIO_CTC,
};

static struct ccwgroup_driver ctcm_group_driver = {
        .driver = {
                .owner  = THIS_MODULE,
                .name   = CTC_DRIVER_NAME,
        },
        .ccw_driver  = &ctcm_ccw_driver,
        .setup       = ctcm_probe_device,
        .remove      = ctcm_remove_device,
        .set_online  = ctcm_new_device,
        .set_offline = ctcm_shutdown_device,
};

static ssize_t group_store(struct device_driver *ddrv, const char *buf,
                           size_t count)
{
        int err;

        err = ccwgroup_create_dev(ctcm_root_dev, &ctcm_group_driver, 2, buf);
        return err ? err : count;
}
static DRIVER_ATTR_WO(group);

static struct attribute *ctcm_drv_attrs[] = {
        &driver_attr_group.attr,
        NULL,
};
static struct attribute_group ctcm_drv_attr_group = {
        .attrs = ctcm_drv_attrs,
};
static const struct attribute_group *ctcm_drv_attr_groups[] = {
        &ctcm_drv_attr_group,
        NULL,
};

/*
 * Module related routines
 */

/*
 * Prepare to be unloaded. Free IRQ's and release all resources.
 * This is called just before this module is unloaded. It is
 * not called, if the usage count is !0, so we don't need to check
 * for that.
 */
static void __exit ctcm_exit(void)
{
        ccwgroup_driver_unregister(&ctcm_group_driver);
        ccw_driver_unregister(&ctcm_ccw_driver);
        root_device_unregister(ctcm_root_dev);
        ctcm_unregister_dbf_views();
        pr_info("CTCM driver unloaded\n");
}

/*
 * Print Banner.
 */
static void print_banner(void)
{
        pr_info("CTCM driver initialized\n");
}

/*
 * Initialize module.
 * This is called just after the module is loaded.
 *
 * returns 0 on success, !0 on error.
 */
static int __init ctcm_init(void)
{
        int ret;

        channels = NULL;

        ret = ctcm_register_dbf_views();
        if (ret)
                goto out_err;
        ctcm_root_dev = root_device_register("ctcm");
        ret = PTR_ERR_OR_ZERO(ctcm_root_dev);
        if (ret)
                goto register_err;
        ret = ccw_driver_register(&ctcm_ccw_driver);
        if (ret)
                goto ccw_err;
        ctcm_group_driver.driver.groups = ctcm_drv_attr_groups;
        ret = ccwgroup_driver_register(&ctcm_group_driver);
        if (ret)
                goto ccwgroup_err;
        print_banner();
        return 0;

ccwgroup_err:
        ccw_driver_unregister(&ctcm_ccw_driver);
ccw_err:
        root_device_unregister(ctcm_root_dev);
register_err:
        ctcm_unregister_dbf_views();
out_err:
        pr_err("%s / Initializing the ctcm device driver failed, ret = %d\n",
                __func__, ret);
        return ret;
}

module_init(ctcm_init);
module_exit(ctcm_exit);

MODULE_AUTHOR("Peter Tiedemann <ptiedem@de.ibm.com>");
MODULE_DESCRIPTION("Network driver for S/390 CTC + CTCMPC (SNA)");
MODULE_LICENSE("GPL");