caif_hsi.c

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/*
 * Copyright (C) ST-Ericsson AB 2010
 * Contact: Sjur Brendeland / [email protected]
 * Author:  Daniel Martensson / [email protected]
 *      Dmitry.Tarnyagin  / [email protected]
 * License terms: GNU General Public License (GPL) version 2.
 */

#define pr_fmt(fmt) KBUILD_MODNAME fmt

#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/netdevice.h>
#include <linux/string.h>
#include <linux/list.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/if_arp.h>
#include <linux/timer.h>
#include <net/rtnetlink.h>
#include <linux/pkt_sched.h>
#include <net/caif/caif_layer.h>
#include <net/caif/caif_hsi.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Daniel Martensson<[email protected]>");
MODULE_DESCRIPTION("CAIF HSI driver");

/* Returns the number of padding bytes for alignment. */
#define PAD_POW2(x, pow) ((((x)&((pow)-1)) == 0) ? 0 :\
                (((pow)-((x)&((pow)-1)))))

static const struct cfhsi_config  hsi_default_config = {

    /* Inactivity timeout on HSI, ms */
    .inactivity_timeout = HZ,

    /* Aggregation timeout (ms) of zero means no aggregation is done*/
    .aggregation_timeout = 1,

    /*
     * HSI link layer flow-control thresholds.
     * Threshold values for the HSI packet queue. Flow-control will be
     * asserted when the number of packets exceeds q_high_mark. It will
     * not be de-asserted before the number of packets drops below
     * q_low_mark.
     * Warning: A high threshold value might increase throughput but it
     * will at the same time prevent channel prioritization and increase
     * the risk of flooding the modem. The high threshold should be above
     * the low.
     */
    .q_high_mark = 100,
    .q_low_mark = 50,

    /*
     * HSI padding options.
     * Warning: must be a base of 2 (& operation used) and can not be zero !
     */
    .head_align = 4,
    .tail_align = 4,
};

#define ON 1
#define OFF 0

static LIST_HEAD(cfhsi_list);

static void cfhsi_inactivity_tout(unsigned long arg)
{
    struct cfhsi *cfhsi = (struct cfhsi *)arg;

    netdev_dbg(cfhsi->ndev, "%s.\n",
        __func__);

    /* Schedule power down work queue. */
    if (!test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
        queue_work(cfhsi->wq, &cfhsi->wake_down_work);
}

static void cfhsi_update_aggregation_stats(struct cfhsi *cfhsi,
                       const struct sk_buff *skb,
                       int direction)
{
    struct caif_payload_info *info;
    int hpad, tpad, len;

    info = (struct caif_payload_info *)&skb->cb;
    hpad = 1 + PAD_POW2((info->hdr_len + 1), cfhsi->cfg.head_align);
    tpad = PAD_POW2((skb->len + hpad), cfhsi->cfg.tail_align);
    len = skb->len + hpad + tpad;

    if (direction > 0)
        cfhsi->aggregation_len += len;
    else if (direction < 0)
        cfhsi->aggregation_len -= len;
}

static bool cfhsi_can_send_aggregate(struct cfhsi *cfhsi)
{
    int i;

    if (cfhsi->cfg.aggregation_timeout == 0)
        return true;

    for (i = 0; i < CFHSI_PRIO_BEBK; ++i) {
        if (cfhsi->qhead[i].qlen)
            return true;
    }

    /* TODO: Use aggregation_len instead */
    if (cfhsi->qhead[CFHSI_PRIO_BEBK].qlen >= CFHSI_MAX_PKTS)
        return true;

    return false;
}

static struct sk_buff *cfhsi_dequeue(struct cfhsi *cfhsi)
{
    struct sk_buff *skb;
    int i;

    for (i = 0; i < CFHSI_PRIO_LAST; ++i) {
        skb = skb_dequeue(&cfhsi->qhead[i]);
        if (skb)
            break;
    }

    return skb;
}

static int cfhsi_tx_queue_len(struct cfhsi *cfhsi)
{
    int i, len = 0;
    for (i = 0; i < CFHSI_PRIO_LAST; ++i)
        len += skb_queue_len(&cfhsi->qhead[i]);
    return len;
}

static void cfhsi_abort_tx(struct cfhsi *cfhsi)
{
    struct sk_buff *skb;

    for (;;) {
        spin_lock_bh(&cfhsi->lock);
        skb = cfhsi_dequeue(cfhsi);
        if (!skb)
            break;

        cfhsi->ndev->stats.tx_errors++;
        cfhsi->ndev->stats.tx_dropped++;
        cfhsi_update_aggregation_stats(cfhsi, skb, -1);
        spin_unlock_bh(&cfhsi->lock);
        kfree_skb(skb);
    }
    cfhsi->tx_state = CFHSI_TX_STATE_IDLE;
    if (!test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
        mod_timer(&cfhsi->inactivity_timer,
            jiffies + cfhsi->cfg.inactivity_timeout);
    spin_unlock_bh(&cfhsi->lock);
}

static int cfhsi_flush_fifo(struct cfhsi *cfhsi)
{
    char buffer[32]; /* Any reasonable value */
    size_t fifo_occupancy;
    int ret;

    netdev_dbg(cfhsi->ndev, "%s.\n",
        __func__);

    do {
        ret = cfhsi->ops->cfhsi_fifo_occupancy(cfhsi->ops,
                &fifo_occupancy);
        if (ret) {
            netdev_warn(cfhsi->ndev,
                "%s: can't get FIFO occupancy: %d.\n",
                __func__, ret);
            break;
        } else if (!fifo_occupancy)
            /* No more data, exitting normally */
            break;

        fifo_occupancy = min(sizeof(buffer), fifo_occupancy);
        set_bit(CFHSI_FLUSH_FIFO, &cfhsi->bits);
        ret = cfhsi->ops->cfhsi_rx(buffer, fifo_occupancy,
                cfhsi->ops);
        if (ret) {
            clear_bit(CFHSI_FLUSH_FIFO, &cfhsi->bits);
            netdev_warn(cfhsi->ndev,
                "%s: can't read data: %d.\n",
                __func__, ret);
            break;
        }

        ret = 5 * HZ;
        ret = wait_event_interruptible_timeout(cfhsi->flush_fifo_wait,
             !test_bit(CFHSI_FLUSH_FIFO, &cfhsi->bits), ret);

        if (ret < 0) {
            netdev_warn(cfhsi->ndev,
                "%s: can't wait for flush complete: %d.\n",
                __func__, ret);
            break;
        } else if (!ret) {
            ret = -ETIMEDOUT;
            netdev_warn(cfhsi->ndev,
                "%s: timeout waiting for flush complete.\n",
                __func__);
            break;
        }
    } while (1);

    return ret;
}

static int cfhsi_tx_frm(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
{
    int nfrms = 0;
    int pld_len = 0;
    struct sk_buff *skb;
    u8 *pfrm = desc->emb_frm + CFHSI_MAX_EMB_FRM_SZ;

    skb = cfhsi_dequeue(cfhsi);
    if (!skb)
        return 0;

    /* Clear offset. */
    desc->offset = 0;

    /* Check if we can embed a CAIF frame. */
    if (skb->len < CFHSI_MAX_EMB_FRM_SZ) {
        struct caif_payload_info *info;
        int hpad;
        int tpad;

        /* Calculate needed head alignment and tail alignment. */
        info = (struct caif_payload_info *)&skb->cb;

        hpad = 1 + PAD_POW2((info->hdr_len + 1), cfhsi->cfg.head_align);
        tpad = PAD_POW2((skb->len + hpad), cfhsi->cfg.tail_align);

        /* Check if frame still fits with added alignment. */
        if ((skb->len + hpad + tpad) <= CFHSI_MAX_EMB_FRM_SZ) {
            u8 *pemb = desc->emb_frm;
            desc->offset = CFHSI_DESC_SHORT_SZ;
            *pemb = (u8)(hpad - 1);
            pemb += hpad;

            /* Update network statistics. */
            spin_lock_bh(&cfhsi->lock);
            cfhsi->ndev->stats.tx_packets++;
            cfhsi->ndev->stats.tx_bytes += skb->len;
            cfhsi_update_aggregation_stats(cfhsi, skb, -1);
            spin_unlock_bh(&cfhsi->lock);

            /* Copy in embedded CAIF frame. */
            skb_copy_bits(skb, 0, pemb, skb->len);

            /* Consume the SKB */
            consume_skb(skb);
            skb = NULL;
        }
    }

    /* Create payload CAIF frames. */
    pfrm = desc->emb_frm + CFHSI_MAX_EMB_FRM_SZ;
    while (nfrms < CFHSI_MAX_PKTS) {
        struct caif_payload_info *info;
        int hpad;
        int tpad;

        if (!skb)
            skb = cfhsi_dequeue(cfhsi);

        if (!skb)
            break;

        /* Calculate needed head alignment and tail alignment. */
        info = (struct caif_payload_info *)&skb->cb;

        hpad = 1 + PAD_POW2((info->hdr_len + 1), cfhsi->cfg.head_align);
        tpad = PAD_POW2((skb->len + hpad), cfhsi->cfg.tail_align);

        /* Fill in CAIF frame length in descriptor. */
        desc->cffrm_len[nfrms] = hpad + skb->len + tpad;

        /* Fill head padding information. */
        *pfrm = (u8)(hpad - 1);
        pfrm += hpad;

        /* Update network statistics. */
        spin_lock_bh(&cfhsi->lock);
        cfhsi->ndev->stats.tx_packets++;
        cfhsi->ndev->stats.tx_bytes += skb->len;
        cfhsi_update_aggregation_stats(cfhsi, skb, -1);
        spin_unlock_bh(&cfhsi->lock);

        /* Copy in CAIF frame. */
        skb_copy_bits(skb, 0, pfrm, skb->len);

        /* Update payload length. */
        pld_len += desc->cffrm_len[nfrms];

        /* Update frame pointer. */
        pfrm += skb->len + tpad;

        /* Consume the SKB */
        consume_skb(skb);
        skb = NULL;

        /* Update number of frames. */
        nfrms++;
    }

    /* Unused length fields should be zero-filled (according to SPEC). */
    while (nfrms < CFHSI_MAX_PKTS) {
        desc->cffrm_len[nfrms] = 0x0000;
        nfrms++;
    }

    /* Check if we can piggy-back another descriptor. */
    if (cfhsi_can_send_aggregate(cfhsi))
        desc->header |= CFHSI_PIGGY_DESC;
    else
        desc->header &= ~CFHSI_PIGGY_DESC;

    return CFHSI_DESC_SZ + pld_len;
}

static void cfhsi_start_tx(struct cfhsi *cfhsi)
{
    struct cfhsi_desc *desc = (struct cfhsi_desc *)cfhsi->tx_buf;
    int len, res;

    netdev_dbg(cfhsi->ndev, "%s.\n", __func__);

    if (test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
        return;

    do {
        /* Create HSI frame. */
        len = cfhsi_tx_frm(desc, cfhsi);
        if (!len) {
            spin_lock_bh(&cfhsi->lock);
            if (unlikely(cfhsi_tx_queue_len(cfhsi))) {
                spin_unlock_bh(&cfhsi->lock);
                res = -EAGAIN;
                continue;
            }
            cfhsi->tx_state = CFHSI_TX_STATE_IDLE;
            /* Start inactivity timer. */
            mod_timer(&cfhsi->inactivity_timer,
                jiffies + cfhsi->cfg.inactivity_timeout);
            spin_unlock_bh(&cfhsi->lock);
            break;
        }

        /* Set up new transfer. */
        res = cfhsi->ops->cfhsi_tx(cfhsi->tx_buf, len, cfhsi->ops);
        if (WARN_ON(res < 0))
            netdev_err(cfhsi->ndev, "%s: TX error %d.\n",
                __func__, res);
    } while (res < 0);
}

static void cfhsi_tx_done(struct cfhsi *cfhsi)
{
    netdev_dbg(cfhsi->ndev, "%s.\n", __func__);

    if (test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
        return;

    /*
     * Send flow on if flow off has been previously signalled
     * and number of packets is below low water mark.
     */
    spin_lock_bh(&cfhsi->lock);
    if (cfhsi->flow_off_sent &&
            cfhsi_tx_queue_len(cfhsi) <= cfhsi->cfg.q_low_mark &&
            cfhsi->cfdev.flowctrl) {

        cfhsi->flow_off_sent = 0;
        cfhsi->cfdev.flowctrl(cfhsi->ndev, ON);
    }

    if (cfhsi_can_send_aggregate(cfhsi)) {
        spin_unlock_bh(&cfhsi->lock);
        cfhsi_start_tx(cfhsi);
    } else {
        mod_timer(&cfhsi->aggregation_timer,
            jiffies + cfhsi->cfg.aggregation_timeout);
        spin_unlock_bh(&cfhsi->lock);
    }

    return;
}

static void cfhsi_tx_done_cb(struct cfhsi_cb_ops *cb_ops)
{
    struct cfhsi *cfhsi;

    cfhsi = container_of(cb_ops, struct cfhsi, cb_ops);
    netdev_dbg(cfhsi->ndev, "%s.\n",
        __func__);

    if (test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
        return;
    cfhsi_tx_done(cfhsi);
}

static int cfhsi_rx_desc(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
{
    int xfer_sz = 0;
    int nfrms = 0;
    u16 *plen = NULL;
    u8 *pfrm = NULL;

    if ((desc->header & ~CFHSI_PIGGY_DESC) ||
            (desc->offset > CFHSI_MAX_EMB_FRM_SZ)) {
        netdev_err(cfhsi->ndev, "%s: Invalid descriptor.\n",
            __func__);
        return -EPROTO;
    }

    /* Check for embedded CAIF frame. */
    if (desc->offset) {
        struct sk_buff *skb;
        u8 *dst = NULL;
        int len = 0;
        pfrm = ((u8 *)desc) + desc->offset;

        /* Remove offset padding. */
        pfrm += *pfrm + 1;

        /* Read length of CAIF frame (little endian). */
        len = *pfrm;
        len |= ((*(pfrm+1)) << 8) & 0xFF00;
        len += 2;   /* Add FCS fields. */

        /* Sanity check length of CAIF frame. */
        if (unlikely(len > CFHSI_MAX_CAIF_FRAME_SZ)) {
            netdev_err(cfhsi->ndev, "%s: Invalid length.\n",
                __func__);
            return -EPROTO;
        }

        /* Allocate SKB (OK even in IRQ context). */
        skb = alloc_skb(len + 1, GFP_ATOMIC);
        if (!skb) {
            netdev_err(cfhsi->ndev, "%s: Out of memory !\n",
                __func__);
            return -ENOMEM;
        }
        caif_assert(skb != NULL);

        dst = skb_put(skb, len);
        memcpy(dst, pfrm, len);

        skb->protocol = htons(ETH_P_CAIF);
        skb_reset_mac_header(skb);
        skb->dev = cfhsi->ndev;

        /*
         * We are in a callback handler and
         * unfortunately we don't know what context we're
         * running in.
         */
        if (in_interrupt())
            netif_rx(skb);
        else
            netif_rx_ni(skb);

        /* Update network statistics. */
        cfhsi->ndev->stats.rx_packets++;
        cfhsi->ndev->stats.rx_bytes += len;
    }

    /* Calculate transfer length. */
    plen = desc->cffrm_len;
    while (nfrms < CFHSI_MAX_PKTS && *plen) {
        xfer_sz += *plen;
        plen++;
        nfrms++;
    }

    /* Check for piggy-backed descriptor. */
    if (desc->header & CFHSI_PIGGY_DESC)
        xfer_sz += CFHSI_DESC_SZ;

    if ((xfer_sz % 4) || (xfer_sz > (CFHSI_BUF_SZ_RX - CFHSI_DESC_SZ))) {
        netdev_err(cfhsi->ndev,
                "%s: Invalid payload len: %d, ignored.\n",
            __func__, xfer_sz);
        return -EPROTO;
    }
    return xfer_sz;
}

static int cfhsi_rx_desc_len(struct cfhsi_desc *desc)
{
    int xfer_sz = 0;
    int nfrms = 0;
    u16 *plen;

    if ((desc->header & ~CFHSI_PIGGY_DESC) ||
            (desc->offset > CFHSI_MAX_EMB_FRM_SZ)) {

        pr_err("Invalid descriptor. %x %x\n", desc->header,
                desc->offset);
        return -EPROTO;
    }

    /* Calculate transfer length. */
    plen = desc->cffrm_len;
    while (nfrms < CFHSI_MAX_PKTS && *plen) {
        xfer_sz += *plen;
        plen++;
        nfrms++;
    }

    if (xfer_sz % 4) {
        pr_err("Invalid payload len: %d, ignored.\n", xfer_sz);
        return -EPROTO;
    }
    return xfer_sz;
}

static int cfhsi_rx_pld(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
{
    int rx_sz = 0;
    int nfrms = 0;
    u16 *plen = NULL;
    u8 *pfrm = NULL;

    /* Sanity check header and offset. */
    if (WARN_ON((desc->header & ~CFHSI_PIGGY_DESC) ||
            (desc->offset > CFHSI_MAX_EMB_FRM_SZ))) {
        netdev_err(cfhsi->ndev, "%s: Invalid descriptor.\n",
            __func__);
        return -EPROTO;
    }

    /* Set frame pointer to start of payload. */
    pfrm = desc->emb_frm + CFHSI_MAX_EMB_FRM_SZ;
    plen = desc->cffrm_len;

    /* Skip already processed frames. */
    while (nfrms < cfhsi->rx_state.nfrms) {
        pfrm += *plen;
        rx_sz += *plen;
        plen++;
        nfrms++;
    }

    /* Parse payload. */
    while (nfrms < CFHSI_MAX_PKTS && *plen) {
        struct sk_buff *skb;
        u8 *dst = NULL;
        u8 *pcffrm = NULL;
        int len;

        /* CAIF frame starts after head padding. */
        pcffrm = pfrm + *pfrm + 1;

        /* Read length of CAIF frame (little endian). */
        len = *pcffrm;
        len |= ((*(pcffrm + 1)) << 8) & 0xFF00;
        len += 2;   /* Add FCS fields. */

        /* Sanity check length of CAIF frames. */
        if (unlikely(len > CFHSI_MAX_CAIF_FRAME_SZ)) {
            netdev_err(cfhsi->ndev, "%s: Invalid length.\n",
                __func__);
            return -EPROTO;
        }

        /* Allocate SKB (OK even in IRQ context). */
        skb = alloc_skb(len + 1, GFP_ATOMIC);
        if (!skb) {
            netdev_err(cfhsi->ndev, "%s: Out of memory !\n",
                __func__);
            cfhsi->rx_state.nfrms = nfrms;
            return -ENOMEM;
        }
        caif_assert(skb != NULL);

        dst = skb_put(skb, len);
        memcpy(dst, pcffrm, len);

        skb->protocol = htons(ETH_P_CAIF);
        skb_reset_mac_header(skb);
        skb->dev = cfhsi->ndev;

        /*
         * We're called in callback from HSI
         * and don't know the context we're running in.
         */
        if (in_interrupt())
            netif_rx(skb);
        else
            netif_rx_ni(skb);

        /* Update network statistics. */
        cfhsi->ndev->stats.rx_packets++;
        cfhsi->ndev->stats.rx_bytes += len;

        pfrm += *plen;
        rx_sz += *plen;
        plen++;
        nfrms++;
    }

    return rx_sz;
}

static void cfhsi_rx_done(struct cfhsi *cfhsi)
{
    int res;
    int desc_pld_len = 0, rx_len, rx_state;
    struct cfhsi_desc *desc = NULL;
    u8 *rx_ptr, *rx_buf;
    struct cfhsi_desc *piggy_desc = NULL;

    desc = (struct cfhsi_desc *)cfhsi->rx_buf;

    netdev_dbg(cfhsi->ndev, "%s\n", __func__);

    if (test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
        return;

    /* Update inactivity timer if pending. */
    spin_lock_bh(&cfhsi->lock);
    mod_timer_pending(&cfhsi->inactivity_timer,
            jiffies + cfhsi->cfg.inactivity_timeout);
    spin_unlock_bh(&cfhsi->lock);

    if (cfhsi->rx_state.state == CFHSI_RX_STATE_DESC) {
        desc_pld_len = cfhsi_rx_desc_len(desc);

        if (desc_pld_len < 0)
            goto out_of_sync;

        rx_buf = cfhsi->rx_buf;
        rx_len = desc_pld_len;
        if (desc_pld_len > 0 && (desc->header & CFHSI_PIGGY_DESC))
            rx_len += CFHSI_DESC_SZ;
        if (desc_pld_len == 0)
            rx_buf = cfhsi->rx_flip_buf;
    } else {
        rx_buf = cfhsi->rx_flip_buf;

        rx_len = CFHSI_DESC_SZ;
        if (cfhsi->rx_state.pld_len > 0 &&
                (desc->header & CFHSI_PIGGY_DESC)) {

            piggy_desc = (struct cfhsi_desc *)
                (desc->emb_frm + CFHSI_MAX_EMB_FRM_SZ +
                        cfhsi->rx_state.pld_len);

            cfhsi->rx_state.piggy_desc = true;

            /* Extract payload len from piggy-backed descriptor. */
            desc_pld_len = cfhsi_rx_desc_len(piggy_desc);
            if (desc_pld_len < 0)
                goto out_of_sync;

            if (desc_pld_len > 0) {
                rx_len = desc_pld_len;
                if (piggy_desc->header & CFHSI_PIGGY_DESC)
                    rx_len += CFHSI_DESC_SZ;
            }

            /*
             * Copy needed information from the piggy-backed
             * descriptor to the descriptor in the start.
             */
            memcpy(rx_buf, (u8 *)piggy_desc,
                    CFHSI_DESC_SHORT_SZ);
        }
    }

    if (desc_pld_len) {
        rx_state = CFHSI_RX_STATE_PAYLOAD;
        rx_ptr = rx_buf + CFHSI_DESC_SZ;
    } else {
        rx_state = CFHSI_RX_STATE_DESC;
        rx_ptr = rx_buf;
        rx_len = CFHSI_DESC_SZ;
    }

    /* Initiate next read */
    if (test_bit(CFHSI_AWAKE, &cfhsi->bits)) {
        /* Set up new transfer. */
        netdev_dbg(cfhsi->ndev, "%s: Start RX.\n",
                __func__);

        res = cfhsi->ops->cfhsi_rx(rx_ptr, rx_len,
                cfhsi->ops);
        if (WARN_ON(res < 0)) {
            netdev_err(cfhsi->ndev, "%s: RX error %d.\n",
                __func__, res);
            cfhsi->ndev->stats.rx_errors++;
            cfhsi->ndev->stats.rx_dropped++;
        }
    }

    if (cfhsi->rx_state.state == CFHSI_RX_STATE_DESC) {
        /* Extract payload from descriptor */
        if (cfhsi_rx_desc(desc, cfhsi) < 0)
            goto out_of_sync;
    } else {
        /* Extract payload */
        if (cfhsi_rx_pld(desc, cfhsi) < 0)
            goto out_of_sync;
        if (piggy_desc) {
            /* Extract any payload in piggyback descriptor. */
            if (cfhsi_rx_desc(piggy_desc, cfhsi) < 0)
                goto out_of_sync;
            /* Mark no embedded frame after extracting it */
            piggy_desc->offset = 0;
        }
    }

    /* Update state info */
    memset(&cfhsi->rx_state, 0, sizeof(cfhsi->rx_state));
    cfhsi->rx_state.state = rx_state;
    cfhsi->rx_ptr = rx_ptr;
    cfhsi->rx_len = rx_len;
    cfhsi->rx_state.pld_len = desc_pld_len;
    cfhsi->rx_state.piggy_desc = desc->header & CFHSI_PIGGY_DESC;

    if (rx_buf != cfhsi->rx_buf)
        swap(cfhsi->rx_buf, cfhsi->rx_flip_buf);
    return;

out_of_sync:
    netdev_err(cfhsi->ndev, "%s: Out of sync.\n", __func__);
    print_hex_dump_bytes("--> ", DUMP_PREFIX_NONE,
            cfhsi->rx_buf, CFHSI_DESC_SZ);
    schedule_work(&cfhsi->out_of_sync_work);
}

static void cfhsi_rx_slowpath(unsigned long arg)
{
    struct cfhsi *cfhsi = (struct cfhsi *)arg;

    netdev_dbg(cfhsi->ndev, "%s.\n",
        __func__);

    cfhsi_rx_done(cfhsi);
}

static void cfhsi_rx_done_cb(struct cfhsi_cb_ops *cb_ops)
{
    struct cfhsi *cfhsi;

    cfhsi = container_of(cb_ops, struct cfhsi, cb_ops);
    netdev_dbg(cfhsi->ndev, "%s.\n",
        __func__);

    if (test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
        return;

    if (test_and_clear_bit(CFHSI_FLUSH_FIFO, &cfhsi->bits))
        wake_up_interruptible(&cfhsi->flush_fifo_wait);
    else
        cfhsi_rx_done(cfhsi);
}

static void cfhsi_wake_up(struct work_struct *work)
{
    struct cfhsi *cfhsi = NULL;
    int res;
    int len;
    long ret;

    cfhsi = container_of(work, struct cfhsi, wake_up_work);

    if (test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
        return;

    if (unlikely(test_bit(CFHSI_AWAKE, &cfhsi->bits))) {
        /* It happenes when wakeup is requested by
         * both ends at the same time. */
        clear_bit(CFHSI_WAKE_UP, &cfhsi->bits);
        clear_bit(CFHSI_WAKE_UP_ACK, &cfhsi->bits);
        return;
    }

    /* Activate wake line. */
    cfhsi->ops->cfhsi_wake_up(cfhsi->ops);

    netdev_dbg(cfhsi->ndev, "%s: Start waiting.\n",
        __func__);

    /* Wait for acknowledge. */
    ret = CFHSI_WAKE_TOUT;
    ret = wait_event_interruptible_timeout(cfhsi->wake_up_wait,
                    test_and_clear_bit(CFHSI_WAKE_UP_ACK,
                            &cfhsi->bits), ret);
    if (unlikely(ret < 0)) {
        /* Interrupted by signal. */
        netdev_err(cfhsi->ndev, "%s: Signalled: %ld.\n",
            __func__, ret);

        clear_bit(CFHSI_WAKE_UP, &cfhsi->bits);
        cfhsi->ops->cfhsi_wake_down(cfhsi->ops);
        return;
    } else if (!ret) {
        bool ca_wake = false;
        size_t fifo_occupancy = 0;

        /* Wakeup timeout */
        netdev_dbg(cfhsi->ndev, "%s: Timeout.\n",
            __func__);

        /* Check FIFO to check if modem has sent something. */
        WARN_ON(cfhsi->ops->cfhsi_fifo_occupancy(cfhsi->ops,
                    &fifo_occupancy));

        netdev_dbg(cfhsi->ndev, "%s: Bytes in FIFO: %u.\n",
                __func__, (unsigned) fifo_occupancy);

        /* Check if we misssed the interrupt. */
        WARN_ON(cfhsi->ops->cfhsi_get_peer_wake(cfhsi->ops,
                            &ca_wake));

        if (ca_wake) {
            netdev_err(cfhsi->ndev, "%s: CA Wake missed !.\n",
                __func__);

            /* Clear the CFHSI_WAKE_UP_ACK bit to prevent race. */
            clear_bit(CFHSI_WAKE_UP_ACK, &cfhsi->bits);

            /* Continue execution. */
            goto wake_ack;
        }

        clear_bit(CFHSI_WAKE_UP, &cfhsi->bits);
        cfhsi->ops->cfhsi_wake_down(cfhsi->ops);
        return;
    }
wake_ack:
    netdev_dbg(cfhsi->ndev, "%s: Woken.\n",
        __func__);

    /* Clear power up bit. */
    set_bit(CFHSI_AWAKE, &cfhsi->bits);
    clear_bit(CFHSI_WAKE_UP, &cfhsi->bits);

    /* Resume read operation. */
    netdev_dbg(cfhsi->ndev, "%s: Start RX.\n", __func__);
    res = cfhsi->ops->cfhsi_rx(cfhsi->rx_ptr, cfhsi->rx_len, cfhsi->ops);

    if (WARN_ON(res < 0))
        netdev_err(cfhsi->ndev, "%s: RX err %d.\n", __func__, res);

    /* Clear power up acknowledment. */
    clear_bit(CFHSI_WAKE_UP_ACK, &cfhsi->bits);

    spin_lock_bh(&cfhsi->lock);

    /* Resume transmit if queues are not empty. */
    if (!cfhsi_tx_queue_len(cfhsi)) {
        netdev_dbg(cfhsi->ndev, "%s: Peer wake, start timer.\n",
            __func__);
        /* Start inactivity timer. */
        mod_timer(&cfhsi->inactivity_timer,
                jiffies + cfhsi->cfg.inactivity_timeout);
        spin_unlock_bh(&cfhsi->lock);
        return;
    }

    netdev_dbg(cfhsi->ndev, "%s: Host wake.\n",
        __func__);

    spin_unlock_bh(&cfhsi->lock);

    /* Create HSI frame. */
    len = cfhsi_tx_frm((struct cfhsi_desc *)cfhsi->tx_buf, cfhsi);

    if (likely(len > 0)) {
        /* Set up new transfer. */
        res = cfhsi->ops->cfhsi_tx(cfhsi->tx_buf, len, cfhsi->ops);
        if (WARN_ON(res < 0)) {
            netdev_err(cfhsi->ndev, "%s: TX error %d.\n",
                __func__, res);
            cfhsi_abort_tx(cfhsi);
        }
    } else {
        netdev_err(cfhsi->ndev,
                "%s: Failed to create HSI frame: %d.\n",
                __func__, len);
    }
}

static void cfhsi_wake_down(struct work_struct *work)
{
    long ret;
    struct cfhsi *cfhsi = NULL;
    size_t fifo_occupancy = 0;
    int retry = CFHSI_WAKE_TOUT;

    cfhsi = container_of(work, struct cfhsi, wake_down_work);
    netdev_dbg(cfhsi->ndev, "%s.\n", __func__);

    if (test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
        return;

    /* Deactivate wake line. */
    cfhsi->ops->cfhsi_wake_down(cfhsi->ops);

    /* Wait for acknowledge. */
    ret = CFHSI_WAKE_TOUT;
    ret = wait_event_interruptible_timeout(cfhsi->wake_down_wait,
                    test_and_clear_bit(CFHSI_WAKE_DOWN_ACK,
                            &cfhsi->bits), ret);
    if (ret < 0) {
        /* Interrupted by signal. */
        netdev_err(cfhsi->ndev, "%s: Signalled: %ld.\n",
            __func__, ret);
        return;
    } else if (!ret) {
        bool ca_wake = true;

        /* Timeout */
        netdev_err(cfhsi->ndev, "%s: Timeout.\n", __func__);

        /* Check if we misssed the interrupt. */
        WARN_ON(cfhsi->ops->cfhsi_get_peer_wake(cfhsi->ops,
                            &ca_wake));
        if (!ca_wake)
            netdev_err(cfhsi->ndev, "%s: CA Wake missed !.\n",
                __func__);
    }

    /* Check FIFO occupancy. */
    while (retry) {
        WARN_ON(cfhsi->ops->cfhsi_fifo_occupancy(cfhsi->ops,
                            &fifo_occupancy));

        if (!fifo_occupancy)
            break;

        set_current_state(TASK_INTERRUPTIBLE);
        schedule_timeout(1);
        retry--;
    }

    if (!retry)
        netdev_err(cfhsi->ndev, "%s: FIFO Timeout.\n", __func__);

    /* Clear AWAKE condition. */
    clear_bit(CFHSI_AWAKE, &cfhsi->bits);

    /* Cancel pending RX requests. */
    cfhsi->ops->cfhsi_rx_cancel(cfhsi->ops);
}

static void cfhsi_out_of_sync(struct work_struct *work)
{
    struct cfhsi *cfhsi = NULL;

    cfhsi = container_of(work, struct cfhsi, out_of_sync_work);

    rtnl_lock();
    dev_close(cfhsi->ndev);
    rtnl_unlock();
}

static void cfhsi_wake_up_cb(struct cfhsi_cb_ops *cb_ops)
{
    struct cfhsi *cfhsi = NULL;

    cfhsi = container_of(cb_ops, struct cfhsi, cb_ops);
    netdev_dbg(cfhsi->ndev, "%s.\n",
        __func__);

    set_bit(CFHSI_WAKE_UP_ACK, &cfhsi->bits);
    wake_up_interruptible(&cfhsi->wake_up_wait);

    if (test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
        return;

    /* Schedule wake up work queue if the peer initiates. */
    if (!test_and_set_bit(CFHSI_WAKE_UP, &cfhsi->bits))
        queue_work(cfhsi->wq, &cfhsi->wake_up_work);
}

static void cfhsi_wake_down_cb(struct cfhsi_cb_ops *cb_ops)
{
    struct cfhsi *cfhsi = NULL;

    cfhsi = container_of(cb_ops, struct cfhsi, cb_ops);
    netdev_dbg(cfhsi->ndev, "%s.\n",
        __func__);

    /* Initiating low power is only permitted by the host (us). */
    set_bit(CFHSI_WAKE_DOWN_ACK, &cfhsi->bits);
    wake_up_interruptible(&cfhsi->wake_down_wait);
}

static void cfhsi_aggregation_tout(unsigned long arg)
{
    struct cfhsi *cfhsi = (struct cfhsi *)arg;

    netdev_dbg(cfhsi->ndev, "%s.\n",
        __func__);

    cfhsi_start_tx(cfhsi);
}

static int cfhsi_xmit(struct sk_buff *skb, struct net_device *dev)
{
    struct cfhsi *cfhsi = NULL;
    int start_xfer = 0;
    int timer_active;
    int prio;

    if (!dev)
        return -EINVAL;

    cfhsi = netdev_priv(dev);

    switch (skb->priority) {
    case TC_PRIO_BESTEFFORT:
    case TC_PRIO_FILLER:
    case TC_PRIO_BULK:
        prio = CFHSI_PRIO_BEBK;
        break;
    case TC_PRIO_INTERACTIVE_BULK:
        prio = CFHSI_PRIO_VI;
        break;
    case TC_PRIO_INTERACTIVE:
        prio = CFHSI_PRIO_VO;
        break;
    case TC_PRIO_CONTROL:
    default:
        prio = CFHSI_PRIO_CTL;
        break;
    }

    spin_lock_bh(&cfhsi->lock);

    /* Update aggregation statistics  */
    cfhsi_update_aggregation_stats(cfhsi, skb, 1);

    /* Queue the SKB */
    skb_queue_tail(&cfhsi->qhead[prio], skb);

    /* Sanity check; xmit should not be called after unregister_netdev */
    if (WARN_ON(test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))) {
        spin_unlock_bh(&cfhsi->lock);
        cfhsi_abort_tx(cfhsi);
        return -EINVAL;
    }

    /* Send flow off if number of packets is above high water mark. */
    if (!cfhsi->flow_off_sent &&
        cfhsi_tx_queue_len(cfhsi) > cfhsi->cfg.q_high_mark &&
        cfhsi->cfdev.flowctrl) {
        cfhsi->flow_off_sent = 1;
        cfhsi->cfdev.flowctrl(cfhsi->ndev, OFF);
    }

    if (cfhsi->tx_state == CFHSI_TX_STATE_IDLE) {
        cfhsi->tx_state = CFHSI_TX_STATE_XFER;
        start_xfer = 1;
    }

    if (!start_xfer) {
        /* Send aggregate if it is possible */
        bool aggregate_ready =
            cfhsi_can_send_aggregate(cfhsi) &&
            del_timer(&cfhsi->aggregation_timer) > 0;
        spin_unlock_bh(&cfhsi->lock);
        if (aggregate_ready)
            cfhsi_start_tx(cfhsi);
        return 0;
    }

    /* Delete inactivity timer if started. */
    timer_active = del_timer_sync(&cfhsi->inactivity_timer);

    spin_unlock_bh(&cfhsi->lock);

    if (timer_active) {
        struct cfhsi_desc *desc = (struct cfhsi_desc *)cfhsi->tx_buf;
        int len;
        int res;

        /* Create HSI frame. */
        len = cfhsi_tx_frm(desc, cfhsi);
        WARN_ON(!len);

        /* Set up new transfer. */
        res = cfhsi->ops->cfhsi_tx(cfhsi->tx_buf, len, cfhsi->ops);
        if (WARN_ON(res < 0)) {
            netdev_err(cfhsi->ndev, "%s: TX error %d.\n",
                __func__, res);
            cfhsi_abort_tx(cfhsi);
        }
    } else {
        /* Schedule wake up work queue if the we initiate. */
        if (!test_and_set_bit(CFHSI_WAKE_UP, &cfhsi->bits))
            queue_work(cfhsi->wq, &cfhsi->wake_up_work);
    }

    return 0;
}

static const struct net_device_ops cfhsi_netdevops;

static void cfhsi_setup(struct net_device *dev)
{
    int i;
    struct cfhsi *cfhsi = netdev_priv(dev);
    dev->features = 0;
    dev->type = ARPHRD_CAIF;
    dev->flags = IFF_POINTOPOINT | IFF_NOARP;
    dev->mtu = CFHSI_MAX_CAIF_FRAME_SZ;
    dev->tx_queue_len = 0;
    dev->destructor = free_netdev;
    dev->netdev_ops = &cfhsi_netdevops;
    for (i = 0; i < CFHSI_PRIO_LAST; ++i)
        skb_queue_head_init(&cfhsi->qhead[i]);
    cfhsi->cfdev.link_select = CAIF_LINK_HIGH_BANDW;
    cfhsi->cfdev.use_frag = false;
    cfhsi->cfdev.use_stx = false;
    cfhsi->cfdev.use_fcs = false;
    cfhsi->ndev = dev;
    cfhsi->cfg = hsi_default_config;
}

static int cfhsi_open(struct net_device *ndev)
{
    struct cfhsi *cfhsi = netdev_priv(ndev);
    int res;

    clear_bit(CFHSI_SHUTDOWN, &cfhsi->bits);

    /* Initialize state vaiables. */
    cfhsi->tx_state = CFHSI_TX_STATE_IDLE;
    cfhsi->rx_state.state = CFHSI_RX_STATE_DESC;

    /* Set flow info */
    cfhsi->flow_off_sent = 0;

    /*
     * Allocate a TX buffer with the size of a HSI packet descriptors
     * and the necessary room for CAIF payload frames.
     */
    cfhsi->tx_buf = kzalloc(CFHSI_BUF_SZ_TX, GFP_KERNEL);
    if (!cfhsi->tx_buf) {
        res = -ENODEV;
        goto err_alloc_tx;
    }

    /*
     * Allocate a RX buffer with the size of two HSI packet descriptors and
     * the necessary room for CAIF payload frames.
     */
    cfhsi->rx_buf = kzalloc(CFHSI_BUF_SZ_RX, GFP_KERNEL);
    if (!cfhsi->rx_buf) {
        res = -ENODEV;
        goto err_alloc_rx;
    }

    cfhsi->rx_flip_buf = kzalloc(CFHSI_BUF_SZ_RX, GFP_KERNEL);
    if (!cfhsi->rx_flip_buf) {
        res = -ENODEV;
        goto err_alloc_rx_flip;
    }

    /* Initialize aggregation timeout */
    cfhsi->cfg.aggregation_timeout = hsi_default_config.aggregation_timeout;

    /* Initialize recieve vaiables. */
    cfhsi->rx_ptr = cfhsi->rx_buf;
    cfhsi->rx_len = CFHSI_DESC_SZ;

    /* Initialize spin locks. */
    spin_lock_init(&cfhsi->lock);

    /* Set up the driver. */
    cfhsi->cb_ops.tx_done_cb = cfhsi_tx_done_cb;
    cfhsi->cb_ops.rx_done_cb = cfhsi_rx_done_cb;
    cfhsi->cb_ops.wake_up_cb = cfhsi_wake_up_cb;
    cfhsi->cb_ops.wake_down_cb = cfhsi_wake_down_cb;

    /* Initialize the work queues. */
    INIT_WORK(&cfhsi->wake_up_work, cfhsi_wake_up);
    INIT_WORK(&cfhsi->wake_down_work, cfhsi_wake_down);
    INIT_WORK(&cfhsi->out_of_sync_work, cfhsi_out_of_sync);

    /* Clear all bit fields. */
    clear_bit(CFHSI_WAKE_UP_ACK, &cfhsi->bits);
    clear_bit(CFHSI_WAKE_DOWN_ACK, &cfhsi->bits);
    clear_bit(CFHSI_WAKE_UP, &cfhsi->bits);
    clear_bit(CFHSI_AWAKE, &cfhsi->bits);

    /* Create work thread. */
    cfhsi->wq = create_singlethread_workqueue(cfhsi->ndev->name);
    if (!cfhsi->wq) {
        netdev_err(cfhsi->ndev, "%s: Failed to create work queue.\n",
            __func__);
        res = -ENODEV;
        goto err_create_wq;
    }

    /* Initialize wait queues. */
    init_waitqueue_head(&cfhsi->wake_up_wait);
    init_waitqueue_head(&cfhsi->wake_down_wait);
    init_waitqueue_head(&cfhsi->flush_fifo_wait);

    /* Setup the inactivity timer. */
    init_timer(&cfhsi->inactivity_timer);
    cfhsi->inactivity_timer.data = (unsigned long)cfhsi;
    cfhsi->inactivity_timer.function = cfhsi_inactivity_tout;
    /* Setup the slowpath RX timer. */
    init_timer(&cfhsi->rx_slowpath_timer);
    cfhsi->rx_slowpath_timer.data = (unsigned long)cfhsi;
    cfhsi->rx_slowpath_timer.function = cfhsi_rx_slowpath;
    /* Setup the aggregation timer. */
    init_timer(&cfhsi->aggregation_timer);
    cfhsi->aggregation_timer.data = (unsigned long)cfhsi;
    cfhsi->aggregation_timer.function = cfhsi_aggregation_tout;

    /* Activate HSI interface. */
    res = cfhsi->ops->cfhsi_up(cfhsi->ops);
    if (res) {
        netdev_err(cfhsi->ndev,
            "%s: can't activate HSI interface: %d.\n",
            __func__, res);
        goto err_activate;
    }

    /* Flush FIFO */
    res = cfhsi_flush_fifo(cfhsi);
    if (res) {
        netdev_err(cfhsi->ndev, "%s: Can't flush FIFO: %d.\n",
            __func__, res);
        goto err_net_reg;
    }
    return res;

 err_net_reg:
    cfhsi->ops->cfhsi_down(cfhsi->ops);
 err_activate:
    destroy_workqueue(cfhsi->wq);
 err_create_wq:
    kfree(cfhsi->rx_flip_buf);
 err_alloc_rx_flip:
    kfree(cfhsi->rx_buf);
 err_alloc_rx:
    kfree(cfhsi->tx_buf);
 err_alloc_tx:
    return res;
}

static int cfhsi_close(struct net_device *ndev)
{
    struct cfhsi *cfhsi = netdev_priv(ndev);
    u8 *tx_buf, *rx_buf, *flip_buf;

    /* going to shutdown driver */
    set_bit(CFHSI_SHUTDOWN, &cfhsi->bits);

    /* Flush workqueue */
    flush_workqueue(cfhsi->wq);

    /* Delete timers if pending */
    del_timer_sync(&cfhsi->inactivity_timer);
    del_timer_sync(&cfhsi->rx_slowpath_timer);
    del_timer_sync(&cfhsi->aggregation_timer);

    /* Cancel pending RX request (if any) */
    cfhsi->ops->cfhsi_rx_cancel(cfhsi->ops);

    /* Destroy workqueue */
    destroy_workqueue(cfhsi->wq);

    /* Store bufferes: will be freed later. */
    tx_buf = cfhsi->tx_buf;
    rx_buf = cfhsi->rx_buf;
    flip_buf = cfhsi->rx_flip_buf;
    /* Flush transmit queues. */
    cfhsi_abort_tx(cfhsi);

    /* Deactivate interface */
    cfhsi->ops->cfhsi_down(cfhsi->ops);

    /* Free buffers. */
    kfree(tx_buf);
    kfree(rx_buf);
    kfree(flip_buf);
    return 0;
}

static void cfhsi_uninit(struct net_device *dev)
{
    struct cfhsi *cfhsi = netdev_priv(dev);
    ASSERT_RTNL();
    symbol_put(cfhsi_get_device);
    list_del(&cfhsi->list);
}

static const struct net_device_ops cfhsi_netdevops = {
    .ndo_uninit = cfhsi_uninit,
    .ndo_open = cfhsi_open,
    .ndo_stop = cfhsi_close,
    .ndo_start_xmit = cfhsi_xmit
};

static void cfhsi_netlink_parms(struct nlattr *data[], struct cfhsi *cfhsi)
{
    int i;

    if (!data) {
        pr_debug("no params data found\n");
        return;
    }

    i = __IFLA_CAIF_HSI_INACTIVITY_TOUT;
    /*
     * Inactivity timeout in millisecs. Lowest possible value is 1,
     * and highest possible is NEXT_TIMER_MAX_DELTA.
     */
    if (data[i]) {
        u32 inactivity_timeout = nla_get_u32(data[i]);
        /* Pre-calculate inactivity timeout. */
        cfhsi->cfg.inactivity_timeout = inactivity_timeout * HZ / 1000;
        if (cfhsi->cfg.inactivity_timeout == 0)
            cfhsi->cfg.inactivity_timeout = 1;
        else if (cfhsi->cfg.inactivity_timeout > NEXT_TIMER_MAX_DELTA)
            cfhsi->cfg.inactivity_timeout = NEXT_TIMER_MAX_DELTA;
    }

    i = __IFLA_CAIF_HSI_AGGREGATION_TOUT;
    if (data[i])
        cfhsi->cfg.aggregation_timeout = nla_get_u32(data[i]);

    i = __IFLA_CAIF_HSI_HEAD_ALIGN;
    if (data[i])
        cfhsi->cfg.head_align = nla_get_u32(data[i]);

    i = __IFLA_CAIF_HSI_TAIL_ALIGN;
    if (data[i])
        cfhsi->cfg.tail_align = nla_get_u32(data[i]);

    i = __IFLA_CAIF_HSI_QHIGH_WATERMARK;
    if (data[i])
        cfhsi->cfg.q_high_mark = nla_get_u32(data[i]);

    i = __IFLA_CAIF_HSI_QLOW_WATERMARK;
    if (data[i])
        cfhsi->cfg.q_low_mark = nla_get_u32(data[i]);
}

static int caif_hsi_changelink(struct net_device *dev, struct nlattr *tb[],
                struct nlattr *data[])
{
    cfhsi_netlink_parms(data, netdev_priv(dev));
    netdev_state_change(dev);
    return 0;
}

static const struct nla_policy caif_hsi_policy[__IFLA_CAIF_HSI_MAX + 1] = {
    [__IFLA_CAIF_HSI_INACTIVITY_TOUT] = { .type = NLA_U32, .len = 4 },
    [__IFLA_CAIF_HSI_AGGREGATION_TOUT] = { .type = NLA_U32, .len = 4 },
    [__IFLA_CAIF_HSI_HEAD_ALIGN] = { .type = NLA_U32, .len = 4 },
    [__IFLA_CAIF_HSI_TAIL_ALIGN] = { .type = NLA_U32, .len = 4 },
    [__IFLA_CAIF_HSI_QHIGH_WATERMARK] = { .type = NLA_U32, .len = 4 },
    [__IFLA_CAIF_HSI_QLOW_WATERMARK] = { .type = NLA_U32, .len = 4 },
};

static size_t caif_hsi_get_size(const struct net_device *dev)
{
    int i;
    size_t s = 0;
    for (i = __IFLA_CAIF_HSI_UNSPEC + 1; i < __IFLA_CAIF_HSI_MAX; i++)
        s += nla_total_size(caif_hsi_policy[i].len);
    return s;
}

static int caif_hsi_fill_info(struct sk_buff *skb, const struct net_device *dev)
{
    struct cfhsi *cfhsi = netdev_priv(dev);

    if (nla_put_u32(skb, __IFLA_CAIF_HSI_INACTIVITY_TOUT,
            cfhsi->cfg.inactivity_timeout) ||
        nla_put_u32(skb, __IFLA_CAIF_HSI_AGGREGATION_TOUT,
            cfhsi->cfg.aggregation_timeout) ||
        nla_put_u32(skb, __IFLA_CAIF_HSI_HEAD_ALIGN,
            cfhsi->cfg.head_align) ||
        nla_put_u32(skb, __IFLA_CAIF_HSI_TAIL_ALIGN,
            cfhsi->cfg.tail_align) ||
        nla_put_u32(skb, __IFLA_CAIF_HSI_QHIGH_WATERMARK,
            cfhsi->cfg.q_high_mark) ||
        nla_put_u32(skb, __IFLA_CAIF_HSI_QLOW_WATERMARK,
            cfhsi->cfg.q_low_mark))
        return -EMSGSIZE;

    return 0;
}

static int caif_hsi_newlink(struct net *src_net, struct net_device *dev,
              struct nlattr *tb[], struct nlattr *data[])
{
    struct cfhsi *cfhsi = NULL;
    struct cfhsi_ops *(*get_ops)(void);

    ASSERT_RTNL();

    cfhsi = netdev_priv(dev);
    cfhsi_netlink_parms(data, cfhsi);
    dev_net_set(cfhsi->ndev, src_net);

    get_ops = symbol_get(cfhsi_get_ops);
    if (!get_ops) {
        pr_err("%s: failed to get the cfhsi_ops\n", __func__);
        return -ENODEV;
    }

    /* Assign the HSI device. */
    cfhsi->ops = (*get_ops)();
    if (!cfhsi->ops) {
        pr_err("%s: failed to get the cfhsi_ops\n", __func__);
        goto err;
    }

    /* Assign the driver to this HSI device. */
    cfhsi->ops->cb_ops = &cfhsi->cb_ops;
    if (register_netdevice(dev)) {
        pr_warn("%s: caif_hsi device registration failed\n", __func__);
        goto err;
    }
    /* Add CAIF HSI device to list. */
    list_add_tail(&cfhsi->list, &cfhsi_list);

    return 0;
err:
    symbol_put(cfhsi_get_ops);
    return -ENODEV;
}

static struct rtnl_link_ops caif_hsi_link_ops __read_mostly = {
    .kind       = "cfhsi",
    .priv_size  = sizeof(struct cfhsi),
    .setup      = cfhsi_setup,
    .maxtype    = __IFLA_CAIF_HSI_MAX,
    .policy = caif_hsi_policy,
    .newlink    = caif_hsi_newlink,
    .changelink = caif_hsi_changelink,
    .get_size   = caif_hsi_get_size,
    .fill_info  = caif_hsi_fill_info,
};

static void __exit cfhsi_exit_module(void)
{
    struct list_head *list_node;
    struct list_head *n;
    struct cfhsi *cfhsi;

    rtnl_link_unregister(&caif_hsi_link_ops);

    rtnl_lock();
    list_for_each_safe(list_node, n, &cfhsi_list) {
        cfhsi = list_entry(list_node, struct cfhsi, list);
        unregister_netdev(cfhsi->ndev);
    }
    rtnl_unlock();
}

static int __init cfhsi_init_module(void)
{
    return rtnl_link_register(&caif_hsi_link_ops);
}

module_init(cfhsi_init_module);
module_exit(cfhsi_exit_module);