1/*
  2 *  The NFC Controller Interface is the communication protocol between an
  3 *  NFC Controller (NFCC) and a Device Host (DH).
  4 *
  5 *  Copyright (C) 2011 Texas Instruments, Inc.
  6 *
  7 *  Written by Ilan Elias <ilane@ti.com>
  8 *
  9 *  This program is free software; you can redistribute it and/or modify
 10 *  it under the terms of the GNU General Public License version 2
 11 *  as published by the Free Software Foundation
 12 *
 13 *  This program is distributed in the hope that it will be useful,
 14 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 15 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 16 *  GNU General Public License for more details.
 17 *
 18 *  You should have received a copy of the GNU General Public License
 19 *  along with this program; if not, see <http://www.gnu.org/licenses/>.
 20 *
 21 */
 22
 23#define pr_fmt(fmt) KBUILD_MODNAME ": %s: " fmt, __func__
 24
 25#include <linux/types.h>
 26#include <linux/interrupt.h>
 27#include <linux/wait.h>
 28#include <linux/bitops.h>
 29#include <linux/skbuff.h>
 30
 31#include "../nfc.h"
 32#include <net/nfc/nci.h>
 33#include <net/nfc/nci_core.h>
 34#include <linux/nfc.h>
 35
 36/* Complete data exchange transaction and forward skb to nfc core */
 37void nci_data_exchange_complete(struct nci_dev *ndev, struct sk_buff *skb,
 38				int err)
 39{
 40	data_exchange_cb_t cb = ndev->data_exchange_cb;
 41	void *cb_context = ndev->data_exchange_cb_context;
 42
 43	pr_debug("len %d, err %d\n", skb ? skb->len : 0, err);
 44
 45	/* data exchange is complete, stop the data timer */
 46	del_timer_sync(&ndev->data_timer);
 47	clear_bit(NCI_DATA_EXCHANGE_TO, &ndev->flags);
 48
 49	if (cb) {
 50		ndev->data_exchange_cb = NULL;
 51		ndev->data_exchange_cb_context = NULL;
 52
 53		/* forward skb to nfc core */
 54		cb(cb_context, skb, err);
 55	} else if (skb) {
 56		pr_err("no rx callback, dropping rx data...\n");
 57
 58		/* no waiting callback, free skb */
 59		kfree_skb(skb);
 60	}
 61
 62	clear_bit(NCI_DATA_EXCHANGE, &ndev->flags);
 63}
 64
 65/* ----------------- NCI TX Data ----------------- */
 66
 67static inline void nci_push_data_hdr(struct nci_dev *ndev,
 68				     __u8 conn_id,
 69				     struct sk_buff *skb,
 70				     __u8 pbf)
 71{
 72	struct nci_data_hdr *hdr;
 73	int plen = skb->len;
 74
 75	hdr = (struct nci_data_hdr *) skb_push(skb, NCI_DATA_HDR_SIZE);
 76	hdr->conn_id = conn_id;
 77	hdr->rfu = 0;
 78	hdr->plen = plen;
 79
 80	nci_mt_set((__u8 *)hdr, NCI_MT_DATA_PKT);
 81	nci_pbf_set((__u8 *)hdr, pbf);
 82}
 83
 84static int nci_queue_tx_data_frags(struct nci_dev *ndev,
 85				   __u8 conn_id,
 86				   struct sk_buff *skb) {
 87	int total_len = skb->len;
 88	unsigned char *data = skb->data;
 89	unsigned long flags;
 90	struct sk_buff_head frags_q;
 91	struct sk_buff *skb_frag;
 92	int frag_len;
 93	int rc = 0;
 94
 95	pr_debug("conn_id 0x%x, total_len %d\n", conn_id, total_len);
 96
 97	__skb_queue_head_init(&frags_q);
 98
 99	while (total_len) {
100		frag_len =
101			min_t(int, total_len, ndev->max_data_pkt_payload_size);
102
103		skb_frag = nci_skb_alloc(ndev,
104					 (NCI_DATA_HDR_SIZE + frag_len),
105					 GFP_KERNEL);
106		if (skb_frag == NULL) {
107			rc = -ENOMEM;
108			goto free_exit;
109		}
110		skb_reserve(skb_frag, NCI_DATA_HDR_SIZE);
111
112		/* first, copy the data */
113		memcpy(skb_put(skb_frag, frag_len), data, frag_len);
114
115		/* second, set the header */
116		nci_push_data_hdr(ndev, conn_id, skb_frag,
117				  ((total_len == frag_len) ?
118				   (NCI_PBF_LAST) : (NCI_PBF_CONT)));
119
120		__skb_queue_tail(&frags_q, skb_frag);
121
122		data += frag_len;
123		total_len -= frag_len;
124
125		pr_debug("frag_len %d, remaining total_len %d\n",
126			 frag_len, total_len);
127	}
128
129	/* queue all fragments atomically */
130	spin_lock_irqsave(&ndev->tx_q.lock, flags);
131
132	while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
133		__skb_queue_tail(&ndev->tx_q, skb_frag);
134
135	spin_unlock_irqrestore(&ndev->tx_q.lock, flags);
136
137	/* free the original skb */
138	kfree_skb(skb);
139
140	goto exit;
141
142free_exit:
143	while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
144		kfree_skb(skb_frag);
145
146exit:
147	return rc;
148}
149
150/* Send NCI data */
151int nci_send_data(struct nci_dev *ndev, __u8 conn_id, struct sk_buff *skb)
152{
153	int rc = 0;
154
155	pr_debug("conn_id 0x%x, plen %d\n", conn_id, skb->len);
156
157	/* check if the packet need to be fragmented */
158	if (skb->len <= ndev->max_data_pkt_payload_size) {
159		/* no need to fragment packet */
160		nci_push_data_hdr(ndev, conn_id, skb, NCI_PBF_LAST);
161
162		skb_queue_tail(&ndev->tx_q, skb);
163	} else {
164		/* fragment packet and queue the fragments */
165		rc = nci_queue_tx_data_frags(ndev, conn_id, skb);
166		if (rc) {
167			pr_err("failed to fragment tx data packet\n");
168			goto free_exit;
169		}
170	}
171
172	queue_work(ndev->tx_wq, &ndev->tx_work);
173
174	goto exit;
175
176free_exit:
177	kfree_skb(skb);
178
179exit:
180	return rc;
181}
182
183/* ----------------- NCI RX Data ----------------- */
184
185static void nci_add_rx_data_frag(struct nci_dev *ndev,
186				 struct sk_buff *skb,
187				 __u8 pbf)
188{
189	int reassembly_len;
190	int err = 0;
191
192	if (ndev->rx_data_reassembly) {
193		reassembly_len = ndev->rx_data_reassembly->len;
194
195		/* first, make enough room for the already accumulated data */
196		if (skb_cow_head(skb, reassembly_len)) {
197			pr_err("error adding room for accumulated rx data\n");
198
199			kfree_skb(skb);
200			skb = NULL;
201
202			kfree_skb(ndev->rx_data_reassembly);
203			ndev->rx_data_reassembly = NULL;
204
205			err = -ENOMEM;
206			goto exit;
207		}
208
209		/* second, combine the two fragments */
210		memcpy(skb_push(skb, reassembly_len),
211		       ndev->rx_data_reassembly->data,
212		       reassembly_len);
213
214		/* third, free old reassembly */
215		kfree_skb(ndev->rx_data_reassembly);
216		ndev->rx_data_reassembly = NULL;
217	}
218
219	if (pbf == NCI_PBF_CONT) {
220		/* need to wait for next fragment, store skb and exit */
221		ndev->rx_data_reassembly = skb;
222		return;
223	}
224
225exit:
226	nci_data_exchange_complete(ndev, skb, err);
227}
228
229/* Rx Data packet */
230void nci_rx_data_packet(struct nci_dev *ndev, struct sk_buff *skb)
231{
232	__u8 pbf = nci_pbf(skb->data);
233
234	pr_debug("len %d\n", skb->len);
235
236	pr_debug("NCI RX: MT=data, PBF=%d, conn_id=%d, plen=%d\n",
237		 nci_pbf(skb->data),
238		 nci_conn_id(skb->data),
239		 nci_plen(skb->data));
240
241	/* strip the nci data header */
242	skb_pull(skb, NCI_DATA_HDR_SIZE);
243
244	if (ndev->target_active_prot == NFC_PROTO_MIFARE) {
245		/* frame I/F => remove the status byte */
246		pr_debug("NFC_PROTO_MIFARE => remove the status byte\n");
247		skb_trim(skb, (skb->len - 1));
248	}
249
250	nci_add_rx_data_frag(ndev, skb, pbf);
251}