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 *  Copyright (C) 2014 Marvell International Ltd.
7 *
8 *  Written by Ilan Elias <ilane@ti.com>
9 *
10 *  This program is free software; you can redistribute it and/or modify
11 *  it under the terms of the GNU General Public License version 2
12 *  as published by the Free Software Foundation
13 *
14 *  This program is distributed in the hope that it will be useful,
15 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
16 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17 *  GNU General Public License for more details.
18 *
19 *  You should have received a copy of the GNU General Public License
20 *  along with this program; if not, see <http://www.gnu.org/licenses/>.
21 *
22 */
23
24#define pr_fmt(fmt) KBUILD_MODNAME ": %s: " fmt, __func__
25
26#include <linux/types.h>
27#include <linux/interrupt.h>
28#include <linux/wait.h>
29#include <linux/bitops.h>
30#include <linux/skbuff.h>
31
32#include "../nfc.h"
33#include <net/nfc/nci.h>
34#include <net/nfc/nci_core.h>
35#include <linux/nfc.h>
36
37/* Complete data exchange transaction and forward skb to nfc core */
38void nci_data_exchange_complete(struct nci_dev *ndev, struct sk_buff *skb,
39				__u8 conn_id, int err)
40{
41	struct nci_conn_info    *conn_info;
42	data_exchange_cb_t cb;
43	void *cb_context;
44
45	conn_info = nci_get_conn_info_by_conn_id(ndev, conn_id);
46	if (!conn_info) {
47		kfree_skb(skb);
48		goto exit;
49	}
50
51	cb = conn_info->data_exchange_cb;
52	cb_context = conn_info->data_exchange_cb_context;
53
54	pr_debug("len %d, err %d\n", skb ? skb->len : 0, err);
55
56	/* data exchange is complete, stop the data timer */
57	del_timer_sync(&ndev->data_timer);
58	clear_bit(NCI_DATA_EXCHANGE_TO, &ndev->flags);
59
60	if (cb) {
61		/* forward skb to nfc core */
62		cb(cb_context, skb, err);
63	} else if (skb) {
64		pr_err("no rx callback, dropping rx data...\n");
65
66		/* no waiting callback, free skb */
67		kfree_skb(skb);
68	}
69
70exit:
71	clear_bit(NCI_DATA_EXCHANGE, &ndev->flags);
72}
73
74/* ----------------- NCI TX Data ----------------- */
75
76static inline void nci_push_data_hdr(struct nci_dev *ndev,
77				     __u8 conn_id,
78				     struct sk_buff *skb,
79				     __u8 pbf)
80{
81	struct nci_data_hdr *hdr;
82	int plen = skb->len;
83
84	hdr = (struct nci_data_hdr *) skb_push(skb, NCI_DATA_HDR_SIZE);
85	hdr->conn_id = conn_id;
86	hdr->rfu = 0;
87	hdr->plen = plen;
88
89	nci_mt_set((__u8 *)hdr, NCI_MT_DATA_PKT);
90	nci_pbf_set((__u8 *)hdr, pbf);
91}
92
93static int nci_queue_tx_data_frags(struct nci_dev *ndev,
94				   __u8 conn_id,
95				   struct sk_buff *skb) {
96	struct nci_conn_info    *conn_info;
97	int total_len = skb->len;
98	unsigned char *data = skb->data;
99	unsigned long flags;
100	struct sk_buff_head frags_q;
101	struct sk_buff *skb_frag;
102	int frag_len;
103	int rc = 0;
104
105	pr_debug("conn_id 0x%x, total_len %d\n", conn_id, total_len);
106
107	conn_info = nci_get_conn_info_by_conn_id(ndev, conn_id);
108	if (!conn_info) {
109		rc = -EPROTO;
110		goto free_exit;
111	}
112
113	__skb_queue_head_init(&frags_q);
114
115	while (total_len) {
116		frag_len =
117			min_t(int, total_len, conn_info->max_pkt_payload_len);
118
119		skb_frag = nci_skb_alloc(ndev,
120					 (NCI_DATA_HDR_SIZE + frag_len),
121					 GFP_KERNEL);
122		if (skb_frag == NULL) {
123			rc = -ENOMEM;
124			goto free_exit;
125		}
126		skb_reserve(skb_frag, NCI_DATA_HDR_SIZE);
127
128		/* first, copy the data */
129		memcpy(skb_put(skb_frag, frag_len), data, frag_len);
130
131		/* second, set the header */
132		nci_push_data_hdr(ndev, conn_id, skb_frag,
133				  ((total_len == frag_len) ?
134				   (NCI_PBF_LAST) : (NCI_PBF_CONT)));
135
136		__skb_queue_tail(&frags_q, skb_frag);
137
138		data += frag_len;
139		total_len -= frag_len;
140
141		pr_debug("frag_len %d, remaining total_len %d\n",
142			 frag_len, total_len);
143	}
144
145	/* queue all fragments atomically */
146	spin_lock_irqsave(&ndev->tx_q.lock, flags);
147
148	while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
149		__skb_queue_tail(&ndev->tx_q, skb_frag);
150
151	spin_unlock_irqrestore(&ndev->tx_q.lock, flags);
152
153	/* free the original skb */
154	kfree_skb(skb);
155
156	goto exit;
157
158free_exit:
159	while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
160		kfree_skb(skb_frag);
161
162exit:
163	return rc;
164}
165
166/* Send NCI data */
167int nci_send_data(struct nci_dev *ndev, __u8 conn_id, struct sk_buff *skb)
168{
169	struct nci_conn_info    *conn_info;
170	int rc = 0;
171
172	pr_debug("conn_id 0x%x, plen %d\n", conn_id, skb->len);
173
174	conn_info = nci_get_conn_info_by_conn_id(ndev, conn_id);
175	if (!conn_info) {
176		rc = -EPROTO;
177		goto free_exit;
178	}
179
180	/* check if the packet need to be fragmented */
181	if (skb->len <= conn_info->max_pkt_payload_len) {
182		/* no need to fragment packet */
183		nci_push_data_hdr(ndev, conn_id, skb, NCI_PBF_LAST);
184
185		skb_queue_tail(&ndev->tx_q, skb);
186	} else {
187		/* fragment packet and queue the fragments */
188		rc = nci_queue_tx_data_frags(ndev, conn_id, skb);
189		if (rc) {
190			pr_err("failed to fragment tx data packet\n");
191			goto free_exit;
192		}
193	}
194
195	ndev->cur_conn_id = conn_id;
196	queue_work(ndev->tx_wq, &ndev->tx_work);
197
198	goto exit;
199
200free_exit:
201	kfree_skb(skb);
202
203exit:
204	return rc;
205}
206
207/* ----------------- NCI RX Data ----------------- */
208
209static void nci_add_rx_data_frag(struct nci_dev *ndev,
210				 struct sk_buff *skb,
211				 __u8 pbf, __u8 conn_id, __u8 status)
212{
213	int reassembly_len;
214	int err = 0;
215
216	if (status) {
217		err = status;
218		goto exit;
219	}
220
221	if (ndev->rx_data_reassembly) {
222		reassembly_len = ndev->rx_data_reassembly->len;
223
224		/* first, make enough room for the already accumulated data */
225		if (skb_cow_head(skb, reassembly_len)) {
226			pr_err("error adding room for accumulated rx data\n");
227
228			kfree_skb(skb);
229			skb = NULL;
230
231			kfree_skb(ndev->rx_data_reassembly);
232			ndev->rx_data_reassembly = NULL;
233
234			err = -ENOMEM;
235			goto exit;
236		}
237
238		/* second, combine the two fragments */
239		memcpy(skb_push(skb, reassembly_len),
240		       ndev->rx_data_reassembly->data,
241		       reassembly_len);
242
243		/* third, free old reassembly */
244		kfree_skb(ndev->rx_data_reassembly);
245		ndev->rx_data_reassembly = NULL;
246	}
247
248	if (pbf == NCI_PBF_CONT) {
249		/* need to wait for next fragment, store skb and exit */
250		ndev->rx_data_reassembly = skb;
251		return;
252	}
253
254exit:
255	if (ndev->nfc_dev->rf_mode == NFC_RF_TARGET) {
256		/* Data received in Target mode, forward to nfc core */
257		err = nfc_tm_data_received(ndev->nfc_dev, skb);
258		if (err)
259			pr_err("unable to handle received data\n");
260	} else {
261		nci_data_exchange_complete(ndev, skb, conn_id, err);
262	}
263}
264
265/* Rx Data packet */
266void nci_rx_data_packet(struct nci_dev *ndev, struct sk_buff *skb)
267{
268	__u8 pbf = nci_pbf(skb->data);
269	__u8 status = 0;
270	__u8 conn_id = nci_conn_id(skb->data);
271	struct nci_conn_info    *conn_info;
272
273	pr_debug("len %d\n", skb->len);
274
275	pr_debug("NCI RX: MT=data, PBF=%d, conn_id=%d, plen=%d\n",
276		 nci_pbf(skb->data),
277		 nci_conn_id(skb->data),
278		 nci_plen(skb->data));
279
280	conn_info = nci_get_conn_info_by_conn_id(ndev, nci_conn_id(skb->data));
281	if (!conn_info)
282		return;
283
284	/* strip the nci data header */
285	skb_pull(skb, NCI_DATA_HDR_SIZE);
286
287	if (ndev->target_active_prot == NFC_PROTO_MIFARE ||
288	    ndev->target_active_prot == NFC_PROTO_JEWEL ||
289	    ndev->target_active_prot == NFC_PROTO_FELICA ||
290	    ndev->target_active_prot == NFC_PROTO_ISO15693) {
291		/* frame I/F => remove the status byte */
292		pr_debug("frame I/F => remove the status byte\n");
293		status = skb->data[skb->len - 1];
294		skb_trim(skb, (skb->len - 1));
295	}
296
297	nci_add_rx_data_frag(ndev, skb, pbf, conn_id, nci_to_errno(status));
298}
299