// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) ST-Ericsson AB 2010
 * Author:  Daniel Martensson
 *          Dmitry.Tarnyagin  / dmitry.tarnyagin@lockless.no
 */

#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");
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(struct timer_list *t)
{
        struct cfhsi *cfhsi = from_timer(cfhsi, t, inactivity_timer);

        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. */
        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;
                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);

                skb_put_data(skb, 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 *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);

                skb_put_data(skb, 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(struct timer_list *t)
{
        struct cfhsi *cfhsi = from_timer(cfhsi, t, rx_slowpath_timer);

        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(struct timer_list *t)
{

        struct cfhsi *cfhsi = from_timer(cfhsi, t, aggregation_timer);

        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->priv_flags |= IFF_NO_QUEUE;
        dev->needs_free_netdev = true;
        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 = alloc_ordered_workqueue(cfhsi->ndev->name, WQ_MEM_RECLAIM);
        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. */
        timer_setup(&cfhsi->inactivity_timer, cfhsi_inactivity_tout, 0);
        /* Setup the slowpath RX timer. */
        timer_setup(&cfhsi->rx_slowpath_timer, cfhsi_rx_slowpath, 0);
        /* Setup the aggregation timer. */
        timer_setup(&cfhsi->aggregation_timer, cfhsi_aggregation_tout, 0);

        /* 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);

        /* 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[],
                               struct netlink_ext_ack *extack)
{
        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 netlink_ext_ack *extack)
{
        struct cfhsi *cfhsi = NULL;
        struct cfhsi_ops *(*get_ops)(void);

        ASSERT_RTNL();

        cfhsi = netdev_priv(dev);
        cfhsi_netlink_parms(data, cfhsi);

        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_netdevice(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);