NFC: basic NCI protocol implementation
The NFC Controller Interface (NCI) is a standard communication protocol between an NFC Controller (NFCC) and a Device Host (DH), defined by the NFC Forum. Signed-off-by: Ilan Elias <ilane@ti.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Ilan Elias
committed by
John W. Linville
John W. Linville
parent
55eb94f9e9
commit
6a2968aaf5
245
net/nfc/nci/data.c
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245
net/nfc/nci/data.c
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/*
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* The NFC Controller Interface is the communication protocol between an
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* NFC Controller (NFCC) and a Device Host (DH).
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*
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* Copyright (C) 2011 Texas Instruments, Inc.
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*
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* Written by Ilan Elias <ilane@ti.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include <linux/types.h>
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#include <linux/interrupt.h>
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#include <linux/wait.h>
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#include <linux/bitops.h>
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#include <linux/skbuff.h>
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#include "../nfc.h"
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#include <net/nfc/nci.h>
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#include <net/nfc/nci_core.h>
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#include <linux/nfc.h>
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/* Complete data exchange transaction and forward skb to nfc core */
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void nci_data_exchange_complete(struct nci_dev *ndev,
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struct sk_buff *skb,
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int err)
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{
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data_exchange_cb_t cb = ndev->data_exchange_cb;
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void *cb_context = ndev->data_exchange_cb_context;
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nfc_dbg("entry, len %d, err %d", ((skb) ? (skb->len) : (0)), err);
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if (cb) {
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ndev->data_exchange_cb = NULL;
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ndev->data_exchange_cb_context = 0;
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/* forward skb to nfc core */
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cb(cb_context, skb, err);
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} else if (skb) {
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nfc_err("no rx callback, dropping rx data...");
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/* no waiting callback, free skb */
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kfree_skb(skb);
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}
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}
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/* ----------------- NCI TX Data ----------------- */
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static inline void nci_push_data_hdr(struct nci_dev *ndev,
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__u8 conn_id,
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struct sk_buff *skb,
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__u8 pbf)
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{
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struct nci_data_hdr *hdr;
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int plen = skb->len;
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hdr = (struct nci_data_hdr *) skb_push(skb, NCI_DATA_HDR_SIZE);
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hdr->conn_id = conn_id;
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hdr->rfu = 0;
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hdr->plen = plen;
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nci_mt_set((__u8 *)hdr, NCI_MT_DATA_PKT);
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nci_pbf_set((__u8 *)hdr, pbf);
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skb->dev = (void *) ndev;
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}
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static int nci_queue_tx_data_frags(struct nci_dev *ndev,
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__u8 conn_id,
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struct sk_buff *skb) {
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int total_len = skb->len;
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unsigned char *data = skb->data;
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unsigned long flags;
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struct sk_buff_head frags_q;
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struct sk_buff *skb_frag;
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int frag_len;
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int rc = 0;
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nfc_dbg("entry, conn_id 0x%x, total_len %d", conn_id, total_len);
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__skb_queue_head_init(&frags_q);
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while (total_len) {
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frag_len = min_t(int, total_len, ndev->max_pkt_payload_size);
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skb_frag = nci_skb_alloc(ndev,
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(NCI_DATA_HDR_SIZE + frag_len),
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GFP_KERNEL);
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if (skb_frag == NULL) {
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rc = -ENOMEM;
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goto free_exit;
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}
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skb_reserve(skb_frag, NCI_DATA_HDR_SIZE);
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/* first, copy the data */
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memcpy(skb_put(skb_frag, frag_len), data, frag_len);
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/* second, set the header */
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nci_push_data_hdr(ndev, conn_id, skb_frag,
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((total_len == frag_len) ? (NCI_PBF_LAST) : (NCI_PBF_CONT)));
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__skb_queue_tail(&frags_q, skb_frag);
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data += frag_len;
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total_len -= frag_len;
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nfc_dbg("frag_len %d, remaining total_len %d",
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frag_len, total_len);
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}
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/* queue all fragments atomically */
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spin_lock_irqsave(&ndev->tx_q.lock, flags);
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while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
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__skb_queue_tail(&ndev->tx_q, skb_frag);
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spin_unlock_irqrestore(&ndev->tx_q.lock, flags);
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/* free the original skb */
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kfree_skb(skb);
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goto exit;
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free_exit:
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while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
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kfree_skb(skb_frag);
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exit:
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return rc;
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}
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/* Send NCI data */
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int nci_send_data(struct nci_dev *ndev, __u8 conn_id, struct sk_buff *skb)
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{
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int rc = 0;
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nfc_dbg("entry, conn_id 0x%x, plen %d", conn_id, skb->len);
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/* check if the packet need to be fragmented */
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if (skb->len <= ndev->max_pkt_payload_size) {
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/* no need to fragment packet */
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nci_push_data_hdr(ndev, conn_id, skb, NCI_PBF_LAST);
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skb_queue_tail(&ndev->tx_q, skb);
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} else {
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/* fragment packet and queue the fragments */
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rc = nci_queue_tx_data_frags(ndev, conn_id, skb);
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if (rc) {
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nfc_err("failed to fragment tx data packet");
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goto free_exit;
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}
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}
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queue_work(ndev->tx_wq, &ndev->tx_work);
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goto exit;
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free_exit:
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kfree_skb(skb);
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exit:
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return rc;
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}
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/* ----------------- NCI RX Data ----------------- */
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static void nci_add_rx_data_frag(struct nci_dev *ndev,
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struct sk_buff *skb,
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__u8 pbf)
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{
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int reassembly_len;
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int err = 0;
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if (ndev->rx_data_reassembly) {
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reassembly_len = ndev->rx_data_reassembly->len;
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/* first, make enough room for the already accumulated data */
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if (skb_cow_head(skb, reassembly_len)) {
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nfc_err("error adding room for accumulated rx data");
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kfree_skb(skb);
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skb = 0;
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kfree_skb(ndev->rx_data_reassembly);
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ndev->rx_data_reassembly = 0;
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err = -ENOMEM;
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goto exit;
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}
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/* second, combine the two fragments */
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memcpy(skb_push(skb, reassembly_len),
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ndev->rx_data_reassembly->data,
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reassembly_len);
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/* third, free old reassembly */
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kfree_skb(ndev->rx_data_reassembly);
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ndev->rx_data_reassembly = 0;
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}
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if (pbf == NCI_PBF_CONT) {
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/* need to wait for next fragment, store skb and exit */
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ndev->rx_data_reassembly = skb;
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return;
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}
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exit:
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nci_data_exchange_complete(ndev, skb, err);
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}
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/* Rx Data packet */
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void nci_rx_data_packet(struct nci_dev *ndev, struct sk_buff *skb)
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{
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__u8 pbf = nci_pbf(skb->data);
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nfc_dbg("entry, len %d", skb->len);
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nfc_dbg("NCI RX: MT=data, PBF=%d, conn_id=%d, plen=%d",
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nci_pbf(skb->data),
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nci_conn_id(skb->data),
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nci_plen(skb->data));
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/* strip the nci data header */
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skb_pull(skb, NCI_DATA_HDR_SIZE);
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if (ndev->target_active_prot == NFC_PROTO_MIFARE) {
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/* frame I/F => remove the status byte */
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nfc_dbg("NFC_PROTO_MIFARE => remove the status byte");
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skb_trim(skb, (skb->len - 1));
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}
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nci_add_rx_data_frag(ndev, skb, pbf);
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}
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