llcp.c

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/*
 * Copyright (C) 2011  Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the
 * Free Software Foundation, Inc.,
 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#define pr_fmt(fmt) "llcp: %s: " fmt, __func__

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/nfc.h>

#include "../nfc.h"
#include "llcp.h"

static u8 llcp_magic[3] = {0x46, 0x66, 0x6d};

static struct list_head llcp_devices;

void nfc_llcp_sock_link(struct llcp_sock_list *l, struct sock *sk)
{
    write_lock(&l->lock);
    sk_add_node(sk, &l->head);
    write_unlock(&l->lock);
}

void nfc_llcp_sock_unlink(struct llcp_sock_list *l, struct sock *sk)
{
    write_lock(&l->lock);
    sk_del_node_init(sk);
    write_unlock(&l->lock);
}

static void nfc_llcp_socket_release(struct nfc_llcp_local *local, bool listen)
{
    struct sock *sk;
    struct hlist_node *node, *tmp;
    struct nfc_llcp_sock *llcp_sock;

    write_lock(&local->sockets.lock);

    sk_for_each_safe(sk, node, tmp, &local->sockets.head) {
        llcp_sock = nfc_llcp_sock(sk);

        bh_lock_sock(sk);

        if (sk->sk_state == LLCP_CONNECTED)
            nfc_put_device(llcp_sock->dev);

        if (sk->sk_state == LLCP_LISTEN) {
            struct nfc_llcp_sock *lsk, *n;
            struct sock *accept_sk;

            list_for_each_entry_safe(lsk, n, &llcp_sock->accept_queue,
                         accept_queue) {
                accept_sk = &lsk->sk;
                bh_lock_sock(accept_sk);

                nfc_llcp_accept_unlink(accept_sk);

                accept_sk->sk_state = LLCP_CLOSED;

                bh_unlock_sock(accept_sk);

                sock_orphan(accept_sk);
            }

            if (listen == true) {
                bh_unlock_sock(sk);
                continue;
            }
        }

        sk->sk_state = LLCP_CLOSED;

        bh_unlock_sock(sk);

        sock_orphan(sk);

        sk_del_node_init(sk);
    }

    write_unlock(&local->sockets.lock);
}

struct nfc_llcp_local *nfc_llcp_local_get(struct nfc_llcp_local *local)
{
    kref_get(&local->ref);

    return local;
}

static void local_release(struct kref *ref)
{
    struct nfc_llcp_local *local;

    local = container_of(ref, struct nfc_llcp_local, ref);

    list_del(&local->list);
    nfc_llcp_socket_release(local, false);
    del_timer_sync(&local->link_timer);
    skb_queue_purge(&local->tx_queue);
    cancel_work_sync(&local->tx_work);
    cancel_work_sync(&local->rx_work);
    cancel_work_sync(&local->timeout_work);
    kfree_skb(local->rx_pending);
    kfree(local);
}

int nfc_llcp_local_put(struct nfc_llcp_local *local)
{
    if (local == NULL)
        return 0;

    return kref_put(&local->ref, local_release);
}

static struct nfc_llcp_sock *nfc_llcp_sock_get(struct nfc_llcp_local *local,
                           u8 ssap, u8 dsap)
{
    struct sock *sk;
    struct hlist_node *node;
    struct nfc_llcp_sock *llcp_sock;

    pr_debug("ssap dsap %d %d\n", ssap, dsap);

    if (ssap == 0 && dsap == 0)
        return NULL;

    read_lock(&local->sockets.lock);

    llcp_sock = NULL;

    sk_for_each(sk, node, &local->sockets.head) {
        llcp_sock = nfc_llcp_sock(sk);

        if (llcp_sock->ssap == ssap && llcp_sock->dsap == dsap)
            break;
    }

    read_unlock(&local->sockets.lock);

    if (llcp_sock == NULL)
        return NULL;

    sock_hold(&llcp_sock->sk);

    return llcp_sock;
}

static void nfc_llcp_sock_put(struct nfc_llcp_sock *sock)
{
    sock_put(&sock->sk);
}

static void nfc_llcp_timeout_work(struct work_struct *work)
{
    struct nfc_llcp_local *local = container_of(work, struct nfc_llcp_local,
                            timeout_work);

    nfc_dep_link_down(local->dev);
}

static void nfc_llcp_symm_timer(unsigned long data)
{
    struct nfc_llcp_local *local = (struct nfc_llcp_local *) data;

    pr_err("SYMM timeout\n");

    schedule_work(&local->timeout_work);
}

struct nfc_llcp_local *nfc_llcp_find_local(struct nfc_dev *dev)
{
    struct nfc_llcp_local *local, *n;

    list_for_each_entry_safe(local, n, &llcp_devices, list)
        if (local->dev == dev)
            return local;

    pr_debug("No device found\n");

    return NULL;
}

static char *wks[] = {
    NULL,
    NULL, /* SDP */
    "urn:nfc:sn:ip",
    "urn:nfc:sn:obex",
    "urn:nfc:sn:snep",
};

static int nfc_llcp_wks_sap(char *service_name, size_t service_name_len)
{
    int sap, num_wks;

    pr_debug("%s\n", service_name);

    if (service_name == NULL)
        return -EINVAL;

    num_wks = ARRAY_SIZE(wks);

    for (sap = 0; sap < num_wks; sap++) {
        if (wks[sap] == NULL)
            continue;

        if (strncmp(wks[sap], service_name, service_name_len) == 0)
            return sap;
    }

    return -EINVAL;
}

static
struct nfc_llcp_sock *nfc_llcp_sock_from_sn(struct nfc_llcp_local *local,
                        u8 *sn, size_t sn_len)
{
    struct sock *sk;
    struct hlist_node *node;
    struct nfc_llcp_sock *llcp_sock, *tmp_sock;

    pr_debug("sn %zd %p\n", sn_len, sn);

    if (sn == NULL || sn_len == 0)
        return NULL;

    read_lock(&local->sockets.lock);

    llcp_sock = NULL;

    sk_for_each(sk, node, &local->sockets.head) {
        tmp_sock = nfc_llcp_sock(sk);

        pr_debug("llcp sock %p\n", tmp_sock);

        if (tmp_sock->sk.sk_state != LLCP_LISTEN)
            continue;

        if (tmp_sock->service_name == NULL ||
            tmp_sock->service_name_len == 0)
            continue;

        if (tmp_sock->service_name_len != sn_len)
            continue;

        if (memcmp(sn, tmp_sock->service_name, sn_len) == 0) {
            llcp_sock = tmp_sock;
            break;
        }
    }

    read_unlock(&local->sockets.lock);

    pr_debug("Found llcp sock %p\n", llcp_sock);

    return llcp_sock;
}

u8 nfc_llcp_get_sdp_ssap(struct nfc_llcp_local *local,
             struct nfc_llcp_sock *sock)
{
    mutex_lock(&local->sdp_lock);

    if (sock->service_name != NULL && sock->service_name_len > 0) {
        int ssap = nfc_llcp_wks_sap(sock->service_name,
                        sock->service_name_len);

        if (ssap > 0) {
            pr_debug("WKS %d\n", ssap);

            /* This is a WKS, let's check if it's free */
            if (local->local_wks & BIT(ssap)) {
                mutex_unlock(&local->sdp_lock);

                return LLCP_SAP_MAX;
            }

            set_bit(ssap, &local->local_wks);
            mutex_unlock(&local->sdp_lock);

            return ssap;
        }

        /*
         * Check if there already is a non WKS socket bound
         * to this service name.
         */
        if (nfc_llcp_sock_from_sn(local, sock->service_name,
                      sock->service_name_len) != NULL) {
            mutex_unlock(&local->sdp_lock);

            return LLCP_SAP_MAX;
        }

        mutex_unlock(&local->sdp_lock);

        return LLCP_SDP_UNBOUND;

    } else if (sock->ssap != 0 && sock->ssap < LLCP_WKS_NUM_SAP) {
        if (!test_bit(sock->ssap, &local->local_wks)) {
            set_bit(sock->ssap, &local->local_wks);
            mutex_unlock(&local->sdp_lock);

            return sock->ssap;
        }
    }

    mutex_unlock(&local->sdp_lock);

    return LLCP_SAP_MAX;
}

u8 nfc_llcp_get_local_ssap(struct nfc_llcp_local *local)
{
    u8 local_ssap;

    mutex_lock(&local->sdp_lock);

    local_ssap = find_first_zero_bit(&local->local_sap, LLCP_LOCAL_NUM_SAP);
    if (local_ssap == LLCP_LOCAL_NUM_SAP) {
        mutex_unlock(&local->sdp_lock);
        return LLCP_SAP_MAX;
    }

    set_bit(local_ssap, &local->local_sap);

    mutex_unlock(&local->sdp_lock);

    return local_ssap + LLCP_LOCAL_SAP_OFFSET;
}

void nfc_llcp_put_ssap(struct nfc_llcp_local *local, u8 ssap)
{
    u8 local_ssap;
    unsigned long *sdp;

    if (ssap < LLCP_WKS_NUM_SAP) {
        local_ssap = ssap;
        sdp = &local->local_wks;
    } else if (ssap < LLCP_LOCAL_NUM_SAP) {
        atomic_t *client_cnt;

        local_ssap = ssap - LLCP_WKS_NUM_SAP;
        sdp = &local->local_sdp;
        client_cnt = &local->local_sdp_cnt[local_ssap];

        pr_debug("%d clients\n", atomic_read(client_cnt));

        mutex_lock(&local->sdp_lock);

        if (atomic_dec_and_test(client_cnt)) {
            struct nfc_llcp_sock *l_sock;

            pr_debug("No more clients for SAP %d\n", ssap);

            clear_bit(local_ssap, sdp);

            /* Find the listening sock and set it back to UNBOUND */
            l_sock = nfc_llcp_sock_get(local, ssap, LLCP_SAP_SDP);
            if (l_sock) {
                l_sock->ssap = LLCP_SDP_UNBOUND;
                nfc_llcp_sock_put(l_sock);
            }
        }

        mutex_unlock(&local->sdp_lock);

        return;
    } else if (ssap < LLCP_MAX_SAP) {
        local_ssap = ssap - LLCP_LOCAL_NUM_SAP;
        sdp = &local->local_sap;
    } else {
        return;
    }

    mutex_lock(&local->sdp_lock);

    clear_bit(local_ssap, sdp);

    mutex_unlock(&local->sdp_lock);
}

static u8 nfc_llcp_reserve_sdp_ssap(struct nfc_llcp_local *local)
{
    u8 ssap;

    mutex_lock(&local->sdp_lock);

    ssap = find_first_zero_bit(&local->local_sdp, LLCP_SDP_NUM_SAP);
    if (ssap == LLCP_SDP_NUM_SAP) {
        mutex_unlock(&local->sdp_lock);

        return LLCP_SAP_MAX;
    }

    pr_debug("SDP ssap %d\n", LLCP_WKS_NUM_SAP + ssap);

    set_bit(ssap, &local->local_sdp);

    mutex_unlock(&local->sdp_lock);

    return LLCP_WKS_NUM_SAP + ssap;
}

static int nfc_llcp_build_gb(struct nfc_llcp_local *local)
{
    u8 *gb_cur, *version_tlv, version, version_length;
    u8 *lto_tlv, lto, lto_length;
    u8 *wks_tlv, wks_length;
    u8 *miux_tlv, miux_length;
    __be16 miux;
    u8 gb_len = 0;
    int ret = 0;

    version = LLCP_VERSION_11;
    version_tlv = nfc_llcp_build_tlv(LLCP_TLV_VERSION, &version,
                     1, &version_length);
    gb_len += version_length;

    /* 1500 ms */
    lto = 150;
    lto_tlv = nfc_llcp_build_tlv(LLCP_TLV_LTO, &lto, 1, &lto_length);
    gb_len += lto_length;

    pr_debug("Local wks 0x%lx\n", local->local_wks);
    wks_tlv = nfc_llcp_build_tlv(LLCP_TLV_WKS, (u8 *)&local->local_wks, 2,
                     &wks_length);
    gb_len += wks_length;

    miux = cpu_to_be16(LLCP_MAX_MIUX);
    miux_tlv = nfc_llcp_build_tlv(LLCP_TLV_MIUX, (u8 *)&miux, 0,
                      &miux_length);
    gb_len += miux_length;

    gb_len += ARRAY_SIZE(llcp_magic);

    if (gb_len > NFC_MAX_GT_LEN) {
        ret = -EINVAL;
        goto out;
    }

    gb_cur = local->gb;

    memcpy(gb_cur, llcp_magic, ARRAY_SIZE(llcp_magic));
    gb_cur += ARRAY_SIZE(llcp_magic);

    memcpy(gb_cur, version_tlv, version_length);
    gb_cur += version_length;

    memcpy(gb_cur, lto_tlv, lto_length);
    gb_cur += lto_length;

    memcpy(gb_cur, wks_tlv, wks_length);
    gb_cur += wks_length;

    memcpy(gb_cur, miux_tlv, miux_length);
    gb_cur += miux_length;

    local->gb_len = gb_len;

out:
    kfree(version_tlv);
    kfree(lto_tlv);
    kfree(wks_tlv);
    kfree(miux_tlv);

    return ret;
}

u8 *nfc_llcp_general_bytes(struct nfc_dev *dev, size_t *general_bytes_len)
{
    struct nfc_llcp_local *local;

    local = nfc_llcp_find_local(dev);
    if (local == NULL) {
        *general_bytes_len = 0;
        return NULL;
    }

    nfc_llcp_build_gb(local);

    *general_bytes_len = local->gb_len;

    return local->gb;
}

int nfc_llcp_set_remote_gb(struct nfc_dev *dev, u8 *gb, u8 gb_len)
{
    struct nfc_llcp_local *local = nfc_llcp_find_local(dev);

    if (local == NULL) {
        pr_err("No LLCP device\n");
        return -ENODEV;
    }

    memset(local->remote_gb, 0, NFC_MAX_GT_LEN);
    memcpy(local->remote_gb, gb, gb_len);
    local->remote_gb_len = gb_len;

    if (local->remote_gb == NULL || local->remote_gb_len == 0)
        return -ENODEV;

    if (memcmp(local->remote_gb, llcp_magic, 3)) {
        pr_err("MAC does not support LLCP\n");
        return -EINVAL;
    }

    return nfc_llcp_parse_gb_tlv(local,
                     &local->remote_gb[3],
                     local->remote_gb_len - 3);
}

static u8 nfc_llcp_dsap(struct sk_buff *pdu)
{
    return (pdu->data[0] & 0xfc) >> 2;
}

static u8 nfc_llcp_ptype(struct sk_buff *pdu)
{
    return ((pdu->data[0] & 0x03) << 2) | ((pdu->data[1] & 0xc0) >> 6);
}

static u8 nfc_llcp_ssap(struct sk_buff *pdu)
{
    return pdu->data[1] & 0x3f;
}

static u8 nfc_llcp_ns(struct sk_buff *pdu)
{
    return pdu->data[2] >> 4;
}

static u8 nfc_llcp_nr(struct sk_buff *pdu)
{
    return pdu->data[2] & 0xf;
}

static void nfc_llcp_set_nrns(struct nfc_llcp_sock *sock, struct sk_buff *pdu)
{
    pdu->data[2] = (sock->send_n << 4) | (sock->recv_n);
    sock->send_n = (sock->send_n + 1) % 16;
    sock->recv_ack_n = (sock->recv_n - 1) % 16;
}

void nfc_llcp_send_to_raw_sock(struct nfc_llcp_local *local,
                   struct sk_buff *skb, u8 direction)
{
    struct hlist_node *node;
    struct sk_buff *skb_copy = NULL, *nskb;
    struct sock *sk;
    u8 *data;

    read_lock(&local->raw_sockets.lock);

    sk_for_each(sk, node, &local->raw_sockets.head) {
        if (sk->sk_state != LLCP_BOUND)
            continue;

        if (skb_copy == NULL) {
            skb_copy = __pskb_copy(skb, NFC_LLCP_RAW_HEADER_SIZE,
                           GFP_ATOMIC);

            if (skb_copy == NULL)
                continue;

            data = skb_push(skb_copy, NFC_LLCP_RAW_HEADER_SIZE);

            data[0] = local->dev ? local->dev->idx : 0xFF;
            data[1] = direction;
        }

        nskb = skb_clone(skb_copy, GFP_ATOMIC);
        if (!nskb)
            continue;

        if (sock_queue_rcv_skb(sk, nskb))
            kfree_skb(nskb);
    }

    read_unlock(&local->raw_sockets.lock);

    kfree_skb(skb_copy);
}

static void nfc_llcp_tx_work(struct work_struct *work)
{
    struct nfc_llcp_local *local = container_of(work, struct nfc_llcp_local,
                            tx_work);
    struct sk_buff *skb;
    struct sock *sk;
    struct nfc_llcp_sock *llcp_sock;

    skb = skb_dequeue(&local->tx_queue);
    if (skb != NULL) {
        sk = skb->sk;
        llcp_sock = nfc_llcp_sock(sk);
        if (llcp_sock != NULL) {
            int ret;

            pr_debug("Sending pending skb\n");
            print_hex_dump(KERN_DEBUG, "LLCP Tx: ",
                       DUMP_PREFIX_OFFSET, 16, 1,
                       skb->data, skb->len, true);

            nfc_llcp_send_to_raw_sock(local, skb,
                          NFC_LLCP_DIRECTION_TX);

            ret = nfc_data_exchange(local->dev, local->target_idx,
                        skb, nfc_llcp_recv, local);

            if (!ret && nfc_llcp_ptype(skb) == LLCP_PDU_I) {
                skb = skb_get(skb);
                skb_queue_tail(&llcp_sock->tx_pending_queue,
                           skb);
            }
        } else {
            nfc_llcp_send_symm(local->dev);
        }
    } else {
        nfc_llcp_send_symm(local->dev);
    }

    mod_timer(&local->link_timer,
          jiffies + msecs_to_jiffies(2 * local->remote_lto));
}

static struct nfc_llcp_sock *nfc_llcp_connecting_sock_get(struct nfc_llcp_local *local,
                              u8 ssap)
{
    struct sock *sk;
    struct nfc_llcp_sock *llcp_sock;
    struct hlist_node *node;

    read_lock(&local->connecting_sockets.lock);

    sk_for_each(sk, node, &local->connecting_sockets.head) {
        llcp_sock = nfc_llcp_sock(sk);

        if (llcp_sock->ssap == ssap) {
            sock_hold(&llcp_sock->sk);
            goto out;
        }
    }

    llcp_sock = NULL;

out:
    read_unlock(&local->connecting_sockets.lock);

    return llcp_sock;
}

static struct nfc_llcp_sock *nfc_llcp_sock_get_sn(struct nfc_llcp_local *local,
                          u8 *sn, size_t sn_len)
{
    struct nfc_llcp_sock *llcp_sock;

    llcp_sock = nfc_llcp_sock_from_sn(local, sn, sn_len);

    if (llcp_sock == NULL)
        return NULL;

    sock_hold(&llcp_sock->sk);

    return llcp_sock;
}

static u8 *nfc_llcp_connect_sn(struct sk_buff *skb, size_t *sn_len)
{
    u8 *tlv = &skb->data[2], type, length;
    size_t tlv_array_len = skb->len - LLCP_HEADER_SIZE, offset = 0;

    while (offset < tlv_array_len) {
        type = tlv[0];
        length = tlv[1];

        pr_debug("type 0x%x length %d\n", type, length);

        if (type == LLCP_TLV_SN) {
            *sn_len = length;
            return &tlv[2];
        }

        offset += length + 2;
        tlv += length + 2;
    }

    return NULL;
}

static void nfc_llcp_recv_connect(struct nfc_llcp_local *local,
                  struct sk_buff *skb)
{
    struct sock *new_sk, *parent;
    struct nfc_llcp_sock *sock, *new_sock;
    u8 dsap, ssap, reason;

    dsap = nfc_llcp_dsap(skb);
    ssap = nfc_llcp_ssap(skb);

    pr_debug("%d %d\n", dsap, ssap);

    if (dsap != LLCP_SAP_SDP) {
        sock = nfc_llcp_sock_get(local, dsap, LLCP_SAP_SDP);
        if (sock == NULL || sock->sk.sk_state != LLCP_LISTEN) {
            reason = LLCP_DM_NOBOUND;
            goto fail;
        }
    } else {
        u8 *sn;
        size_t sn_len;

        sn = nfc_llcp_connect_sn(skb, &sn_len);
        if (sn == NULL) {
            reason = LLCP_DM_NOBOUND;
            goto fail;
        }

        pr_debug("Service name length %zu\n", sn_len);

        sock = nfc_llcp_sock_get_sn(local, sn, sn_len);
        if (sock == NULL) {
            reason = LLCP_DM_NOBOUND;
            goto fail;
        }
    }

    lock_sock(&sock->sk);

    parent = &sock->sk;

    if (sk_acceptq_is_full(parent)) {
        reason = LLCP_DM_REJ;
        release_sock(&sock->sk);
        sock_put(&sock->sk);
        goto fail;
    }

    if (sock->ssap == LLCP_SDP_UNBOUND) {
        u8 ssap = nfc_llcp_reserve_sdp_ssap(local);

        pr_debug("First client, reserving %d\n", ssap);

        if (ssap == LLCP_SAP_MAX) {
            reason = LLCP_DM_REJ;
            release_sock(&sock->sk);
            sock_put(&sock->sk);
            goto fail;
        }

        sock->ssap = ssap;
    }

    new_sk = nfc_llcp_sock_alloc(NULL, parent->sk_type, GFP_ATOMIC);
    if (new_sk == NULL) {
        reason = LLCP_DM_REJ;
        release_sock(&sock->sk);
        sock_put(&sock->sk);
        goto fail;
    }

    new_sock = nfc_llcp_sock(new_sk);
    new_sock->dev = local->dev;
    new_sock->local = nfc_llcp_local_get(local);
    new_sock->miu = local->remote_miu;
    new_sock->nfc_protocol = sock->nfc_protocol;
    new_sock->dsap = ssap;
    new_sock->target_idx = local->target_idx;
    new_sock->parent = parent;
    new_sock->ssap = sock->ssap;
    if (sock->ssap < LLCP_LOCAL_NUM_SAP && sock->ssap >= LLCP_WKS_NUM_SAP) {
        atomic_t *client_count;

        pr_debug("reserved_ssap %d for %p\n", sock->ssap, new_sock);

        client_count =
            &local->local_sdp_cnt[sock->ssap - LLCP_WKS_NUM_SAP];

        atomic_inc(client_count);
        new_sock->reserved_ssap = sock->ssap;
    }

    nfc_llcp_parse_connection_tlv(new_sock, &skb->data[LLCP_HEADER_SIZE],
                      skb->len - LLCP_HEADER_SIZE);

    pr_debug("new sock %p sk %p\n", new_sock, &new_sock->sk);

    nfc_llcp_sock_link(&local->sockets, new_sk);

    nfc_llcp_accept_enqueue(&sock->sk, new_sk);

    nfc_get_device(local->dev->idx);

    new_sk->sk_state = LLCP_CONNECTED;

    /* Wake the listening processes */
    parent->sk_data_ready(parent, 0);

    /* Send CC */
    nfc_llcp_send_cc(new_sock);

    release_sock(&sock->sk);
    sock_put(&sock->sk);

    return;

fail:
    /* Send DM */
    nfc_llcp_send_dm(local, dsap, ssap, reason);

    return;

}

int nfc_llcp_queue_i_frames(struct nfc_llcp_sock *sock)
{
    int nr_frames = 0;
    struct nfc_llcp_local *local = sock->local;

    pr_debug("Remote ready %d tx queue len %d remote rw %d",
         sock->remote_ready, skb_queue_len(&sock->tx_pending_queue),
         sock->rw);

    /* Try to queue some I frames for transmission */
    while (sock->remote_ready &&
           skb_queue_len(&sock->tx_pending_queue) < sock->rw) {
        struct sk_buff *pdu;

        pdu = skb_dequeue(&sock->tx_queue);
        if (pdu == NULL)
            break;

        /* Update N(S)/N(R) */
        nfc_llcp_set_nrns(sock, pdu);

        skb_queue_tail(&local->tx_queue, pdu);
        nr_frames++;
    }

    return nr_frames;
}

static void nfc_llcp_recv_hdlc(struct nfc_llcp_local *local,
                   struct sk_buff *skb)
{
    struct nfc_llcp_sock *llcp_sock;
    struct sock *sk;
    u8 dsap, ssap, ptype, ns, nr;

    ptype = nfc_llcp_ptype(skb);
    dsap = nfc_llcp_dsap(skb);
    ssap = nfc_llcp_ssap(skb);
    ns = nfc_llcp_ns(skb);
    nr = nfc_llcp_nr(skb);

    pr_debug("%d %d R %d S %d\n", dsap, ssap, nr, ns);

    llcp_sock = nfc_llcp_sock_get(local, dsap, ssap);
    if (llcp_sock == NULL) {
        nfc_llcp_send_dm(local, dsap, ssap, LLCP_DM_NOCONN);
        return;
    }

    sk = &llcp_sock->sk;
    lock_sock(sk);
    if (sk->sk_state == LLCP_CLOSED) {
        release_sock(sk);
        nfc_llcp_sock_put(llcp_sock);
    }

    /* Pass the payload upstream */
    if (ptype == LLCP_PDU_I) {
        pr_debug("I frame, queueing on %p\n", &llcp_sock->sk);

        if (ns == llcp_sock->recv_n)
            llcp_sock->recv_n = (llcp_sock->recv_n + 1) % 16;
        else
            pr_err("Received out of sequence I PDU\n");

        skb_pull(skb, LLCP_HEADER_SIZE + LLCP_SEQUENCE_SIZE);
        if (sock_queue_rcv_skb(&llcp_sock->sk, skb)) {
            pr_err("receive queue is full\n");
            skb_queue_head(&llcp_sock->tx_backlog_queue, skb);
        }
    }

    /* Remove skbs from the pending queue */
    if (llcp_sock->send_ack_n != nr) {
        struct sk_buff *s, *tmp;

        llcp_sock->send_ack_n = nr;

        /* Remove and free all skbs until ns == nr */
        skb_queue_walk_safe(&llcp_sock->tx_pending_queue, s, tmp) {
            skb_unlink(s, &llcp_sock->tx_pending_queue);
            kfree_skb(s);

            if (nfc_llcp_ns(s) == nr)
                break;
        }

        /* Re-queue the remaining skbs for transmission */
        skb_queue_reverse_walk_safe(&llcp_sock->tx_pending_queue,
                        s, tmp) {
            skb_unlink(s, &llcp_sock->tx_pending_queue);
            skb_queue_head(&local->tx_queue, s);
        }
    }

    if (ptype == LLCP_PDU_RR)
        llcp_sock->remote_ready = true;
    else if (ptype == LLCP_PDU_RNR)
        llcp_sock->remote_ready = false;

    if (nfc_llcp_queue_i_frames(llcp_sock) == 0 && ptype == LLCP_PDU_I)
        nfc_llcp_send_rr(llcp_sock);

    release_sock(sk);
    nfc_llcp_sock_put(llcp_sock);
}

static void nfc_llcp_recv_disc(struct nfc_llcp_local *local,
                   struct sk_buff *skb)
{
    struct nfc_llcp_sock *llcp_sock;
    struct sock *sk;
    u8 dsap, ssap;

    dsap = nfc_llcp_dsap(skb);
    ssap = nfc_llcp_ssap(skb);

    llcp_sock = nfc_llcp_sock_get(local, dsap, ssap);
    if (llcp_sock == NULL) {
        nfc_llcp_send_dm(local, dsap, ssap, LLCP_DM_NOCONN);
        return;
    }

    sk = &llcp_sock->sk;
    lock_sock(sk);
    if (sk->sk_state == LLCP_CLOSED) {
        release_sock(sk);
        nfc_llcp_sock_put(llcp_sock);
    }

    if (sk->sk_state == LLCP_CONNECTED) {
        nfc_put_device(local->dev);
        sk->sk_state = LLCP_CLOSED;
        sk->sk_state_change(sk);
    }

    nfc_llcp_send_dm(local, dsap, ssap, LLCP_DM_DISC);

    release_sock(sk);
    nfc_llcp_sock_put(llcp_sock);
}

static void nfc_llcp_recv_cc(struct nfc_llcp_local *local, struct sk_buff *skb)
{
    struct nfc_llcp_sock *llcp_sock;
    struct sock *sk;
    u8 dsap, ssap;

    dsap = nfc_llcp_dsap(skb);
    ssap = nfc_llcp_ssap(skb);

    llcp_sock = nfc_llcp_connecting_sock_get(local, dsap);
    if (llcp_sock == NULL) {
        pr_err("Invalid CC\n");
        nfc_llcp_send_dm(local, dsap, ssap, LLCP_DM_NOCONN);

        return;
    }

    sk = &llcp_sock->sk;

    /* Unlink from connecting and link to the client array */
    nfc_llcp_sock_unlink(&local->connecting_sockets, sk);
    nfc_llcp_sock_link(&local->sockets, sk);
    llcp_sock->dsap = ssap;

    nfc_llcp_parse_connection_tlv(llcp_sock, &skb->data[LLCP_HEADER_SIZE],
                      skb->len - LLCP_HEADER_SIZE);

    sk->sk_state = LLCP_CONNECTED;
    sk->sk_state_change(sk);

    nfc_llcp_sock_put(llcp_sock);
}

static void nfc_llcp_recv_dm(struct nfc_llcp_local *local, struct sk_buff *skb)
{
    struct nfc_llcp_sock *llcp_sock;
    struct sock *sk;
    u8 dsap, ssap, reason;

    dsap = nfc_llcp_dsap(skb);
    ssap = nfc_llcp_ssap(skb);
    reason = skb->data[2];

    pr_debug("%d %d reason %d\n", ssap, dsap, reason);

    switch (reason) {
    case LLCP_DM_NOBOUND:
    case LLCP_DM_REJ:
        llcp_sock = nfc_llcp_connecting_sock_get(local, dsap);
        break;

    default:
        llcp_sock = nfc_llcp_sock_get(local, dsap, ssap);
        break;
    }

    if (llcp_sock == NULL) {
        pr_err("Invalid DM\n");
        return;
    }

    sk = &llcp_sock->sk;

    sk->sk_err = ENXIO;
    sk->sk_state = LLCP_CLOSED;
    sk->sk_state_change(sk);

    nfc_llcp_sock_put(llcp_sock);

    return;
}

static void nfc_llcp_rx_work(struct work_struct *work)
{
    struct nfc_llcp_local *local = container_of(work, struct nfc_llcp_local,
                            rx_work);
    u8 dsap, ssap, ptype;
    struct sk_buff *skb;

    skb = local->rx_pending;
    if (skb == NULL) {
        pr_debug("No pending SKB\n");
        return;
    }

    ptype = nfc_llcp_ptype(skb);
    dsap = nfc_llcp_dsap(skb);
    ssap = nfc_llcp_ssap(skb);

    pr_debug("ptype 0x%x dsap 0x%x ssap 0x%x\n", ptype, dsap, ssap);

    if (ptype != LLCP_PDU_SYMM)
        print_hex_dump(KERN_DEBUG, "LLCP Rx: ", DUMP_PREFIX_OFFSET,
                   16, 1, skb->data, skb->len, true);

    nfc_llcp_send_to_raw_sock(local, skb, NFC_LLCP_DIRECTION_RX);

    switch (ptype) {
    case LLCP_PDU_SYMM:
        pr_debug("SYMM\n");
        break;

    case LLCP_PDU_CONNECT:
        pr_debug("CONNECT\n");
        nfc_llcp_recv_connect(local, skb);
        break;

    case LLCP_PDU_DISC:
        pr_debug("DISC\n");
        nfc_llcp_recv_disc(local, skb);
        break;

    case LLCP_PDU_CC:
        pr_debug("CC\n");
        nfc_llcp_recv_cc(local, skb);
        break;

    case LLCP_PDU_DM:
        pr_debug("DM\n");
        nfc_llcp_recv_dm(local, skb);
        break;

    case LLCP_PDU_I:
    case LLCP_PDU_RR:
    case LLCP_PDU_RNR:
        pr_debug("I frame\n");
        nfc_llcp_recv_hdlc(local, skb);
        break;

    }

    schedule_work(&local->tx_work);
    kfree_skb(local->rx_pending);
    local->rx_pending = NULL;

    return;
}

void nfc_llcp_recv(void *data, struct sk_buff *skb, int err)
{
    struct nfc_llcp_local *local = (struct nfc_llcp_local *) data;

    pr_debug("Received an LLCP PDU\n");
    if (err < 0) {
        pr_err("err %d\n", err);
        return;
    }

    local->rx_pending = skb_get(skb);
    del_timer(&local->link_timer);
    schedule_work(&local->rx_work);

    return;
}

int nfc_llcp_data_received(struct nfc_dev *dev, struct sk_buff *skb)
{
    struct nfc_llcp_local *local;

    local = nfc_llcp_find_local(dev);
    if (local == NULL)
        return -ENODEV;

    local->rx_pending = skb_get(skb);
    del_timer(&local->link_timer);
    schedule_work(&local->rx_work);

    return 0;
}

void nfc_llcp_mac_is_down(struct nfc_dev *dev)
{
    struct nfc_llcp_local *local;

    local = nfc_llcp_find_local(dev);
    if (local == NULL)
        return;

    /* Close and purge all existing sockets */
    nfc_llcp_socket_release(local, true);
}

void nfc_llcp_mac_is_up(struct nfc_dev *dev, u32 target_idx,
            u8 comm_mode, u8 rf_mode)
{
    struct nfc_llcp_local *local;

    pr_debug("rf mode %d\n", rf_mode);

    local = nfc_llcp_find_local(dev);
    if (local == NULL)
        return;

    local->target_idx = target_idx;
    local->comm_mode = comm_mode;
    local->rf_mode = rf_mode;

    if (rf_mode == NFC_RF_INITIATOR) {
        pr_debug("Queueing Tx work\n");

        schedule_work(&local->tx_work);
    } else {
        mod_timer(&local->link_timer,
              jiffies + msecs_to_jiffies(local->remote_lto));
    }
}

int nfc_llcp_register_device(struct nfc_dev *ndev)
{
    struct nfc_llcp_local *local;

    local = kzalloc(sizeof(struct nfc_llcp_local), GFP_KERNEL);
    if (local == NULL)
        return -ENOMEM;

    local->dev = ndev;
    INIT_LIST_HEAD(&local->list);
    kref_init(&local->ref);
    mutex_init(&local->sdp_lock);
    init_timer(&local->link_timer);
    local->link_timer.data = (unsigned long) local;
    local->link_timer.function = nfc_llcp_symm_timer;

    skb_queue_head_init(&local->tx_queue);
    INIT_WORK(&local->tx_work, nfc_llcp_tx_work);

    local->rx_pending = NULL;
    INIT_WORK(&local->rx_work, nfc_llcp_rx_work);

    INIT_WORK(&local->timeout_work, nfc_llcp_timeout_work);

    rwlock_init(&local->sockets.lock);
    rwlock_init(&local->connecting_sockets.lock);
    rwlock_init(&local->raw_sockets.lock);

    nfc_llcp_build_gb(local);

    local->remote_miu = LLCP_DEFAULT_MIU;
    local->remote_lto = LLCP_DEFAULT_LTO;

    list_add(&local->list, &llcp_devices);

    return 0;
}

void nfc_llcp_unregister_device(struct nfc_dev *dev)
{
    struct nfc_llcp_local *local = nfc_llcp_find_local(dev);

    if (local == NULL) {
        pr_debug("No such device\n");
        return;
    }

    nfc_llcp_local_put(local);
}

int __init nfc_llcp_init(void)
{
    INIT_LIST_HEAD(&llcp_devices);

    return nfc_llcp_sock_init();
}

void nfc_llcp_exit(void)
{
    nfc_llcp_sock_exit();
}