data.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 *  The NFC Controller Interface is the communication protocol between an
  4 *  NFC Controller (NFCC) and a Device Host (DH).
  5 *
  6 *  Copyright (C) 2011 Texas Instruments, Inc.
  7 *  Copyright (C) 2014 Marvell International Ltd.
  8 *
  9 *  Written by Ilan Elias <ilane@ti.com>
 10 */
 11
 12#define pr_fmt(fmt) KBUILD_MODNAME ": %s: " fmt, __func__
 13
 14#include <linux/types.h>
 15#include <linux/interrupt.h>
 16#include <linux/wait.h>
 17#include <linux/bitops.h>
 18#include <linux/skbuff.h>
 19
 20#include "../nfc.h"
 21#include <net/nfc/nci.h>
 22#include <net/nfc/nci_core.h>
 23#include <linux/nfc.h>
 24
 25/* Complete data exchange transaction and forward skb to nfc core */
 26void nci_data_exchange_complete(struct nci_dev *ndev, struct sk_buff *skb,
 27				__u8 conn_id, int err)
 28{
 29	const struct nci_conn_info *conn_info;
 30	data_exchange_cb_t cb;
 31	void *cb_context;
 32
 33	conn_info = nci_get_conn_info_by_conn_id(ndev, conn_id);
 34	if (!conn_info) {
 35		kfree_skb(skb);
 36		clear_bit(NCI_DATA_EXCHANGE, &ndev->flags);
 37		return;
 38	}
 39
 40	cb = conn_info->data_exchange_cb;
 41	cb_context = conn_info->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	timer_delete_sync(&ndev->data_timer);
 47	clear_bit(NCI_DATA_EXCHANGE_TO, &ndev->flags);
 48
 49	/* Mark the exchange as done before calling the callback.
 50	 * The callback (e.g. rawsock_data_exchange_complete) may
 51	 * want to immediately queue another data exchange.
 52	 */
 53	clear_bit(NCI_DATA_EXCHANGE, &ndev->flags);
 54
 55	if (cb) {
 56		/* forward skb to nfc core */
 57		cb(cb_context, skb, err);
 58	} else if (skb) {
 59		pr_err("no rx callback, dropping rx data...\n");
 60
 61		/* no waiting callback, free skb */
 62		kfree_skb(skb);
 63	}
 64}
 65
 66/* ----------------- NCI TX Data ----------------- */
 67
 68static inline void nci_push_data_hdr(struct nci_dev *ndev,
 69				     __u8 conn_id,
 70				     struct sk_buff *skb,
 71				     __u8 pbf)
 72{
 73	struct nci_data_hdr *hdr;
 74	int plen = skb->len;
 75
 76	hdr = skb_push(skb, NCI_DATA_HDR_SIZE);
 77	hdr->conn_id = conn_id;
 78	hdr->rfu = 0;
 79	hdr->plen = plen;
 80
 81	nci_mt_set((__u8 *)hdr, NCI_MT_DATA_PKT);
 82	nci_pbf_set((__u8 *)hdr, pbf);
 83}
 84
 85int nci_conn_max_data_pkt_payload_size(struct nci_dev *ndev, __u8 conn_id)
 86{
 87	const struct nci_conn_info *conn_info;
 88
 89	conn_info = nci_get_conn_info_by_conn_id(ndev, conn_id);
 90	if (!conn_info)
 91		return -EPROTO;
 92
 93	return conn_info->max_pkt_payload_len;
 94}
 95EXPORT_SYMBOL(nci_conn_max_data_pkt_payload_size);
 96
 97static int nci_queue_tx_data_frags(struct nci_dev *ndev,
 98				   __u8 conn_id,
 99				   struct sk_buff *skb) {
100	const struct nci_conn_info *conn_info;
101	int total_len = skb->len;
102	const unsigned char *data = skb->data;
103	unsigned long flags;
104	struct sk_buff_head frags_q;
105	struct sk_buff *skb_frag;
106	int frag_len;
107	int rc = 0;
108
109	pr_debug("conn_id 0x%x, total_len %d\n", conn_id, total_len);
110
111	conn_info = nci_get_conn_info_by_conn_id(ndev, conn_id);
112	if (!conn_info) {
113		rc = -EPROTO;
114		goto exit;
115	}
116
117	__skb_queue_head_init(&frags_q);
118
119	while (total_len) {
120		frag_len =
121			min_t(int, total_len, conn_info->max_pkt_payload_len);
122
123		skb_frag = nci_skb_alloc(ndev,
124					 (NCI_DATA_HDR_SIZE + frag_len),
125					 GFP_ATOMIC);
126		if (skb_frag == NULL) {
127			rc = -ENOMEM;
128			goto free_exit;
129		}
130		skb_reserve(skb_frag, NCI_DATA_HDR_SIZE);
131
132		/* first, copy the data */
133		skb_put_data(skb_frag, data, frag_len);
134
135		/* second, set the header */
136		nci_push_data_hdr(ndev, conn_id, skb_frag,
137				  ((total_len == frag_len) ?
138				   (NCI_PBF_LAST) : (NCI_PBF_CONT)));
139
140		__skb_queue_tail(&frags_q, skb_frag);
141
142		data += frag_len;
143		total_len -= frag_len;
144
145		pr_debug("frag_len %d, remaining total_len %d\n",
146			 frag_len, total_len);
147	}
148
149	/* queue all fragments atomically */
150	spin_lock_irqsave(&ndev->tx_q.lock, flags);
151
152	while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
153		__skb_queue_tail(&ndev->tx_q, skb_frag);
154
155	spin_unlock_irqrestore(&ndev->tx_q.lock, flags);
156
157	/* free the original skb */
158	kfree_skb(skb);
159
160	goto exit;
161
162free_exit:
163	while ((skb_frag = __skb_dequeue(&frags_q)) != NULL)
164		kfree_skb(skb_frag);
165
166exit:
167	return rc;
168}
169
170/* Send NCI data */
171int nci_send_data(struct nci_dev *ndev, __u8 conn_id, struct sk_buff *skb)
172{
173	const struct nci_conn_info *conn_info;
174	int rc = 0;
175
176	pr_debug("conn_id 0x%x, plen %d\n", conn_id, skb->len);
177
178	conn_info = nci_get_conn_info_by_conn_id(ndev, conn_id);
179	if (!conn_info) {
180		rc = -EPROTO;
181		goto free_exit;
182	}
183
184	/* check if the packet need to be fragmented */
185	if (skb->len <= conn_info->max_pkt_payload_len) {
186		/* no need to fragment packet */
187		nci_push_data_hdr(ndev, conn_id, skb, NCI_PBF_LAST);
188
189		skb_queue_tail(&ndev->tx_q, skb);
190	} else {
191		/* fragment packet and queue the fragments */
192		rc = nci_queue_tx_data_frags(ndev, conn_id, skb);
193		if (rc) {
194			pr_err("failed to fragment tx data packet\n");
195			goto free_exit;
196		}
197	}
198
199	ndev->cur_conn_id = conn_id;
200	queue_work(ndev->tx_wq, &ndev->tx_work);
201
202	goto exit;
203
204free_exit:
205	kfree_skb(skb);
206
207exit:
208	return rc;
209}
210EXPORT_SYMBOL(nci_send_data);
211
212/* ----------------- NCI RX Data ----------------- */
213
214static void nci_add_rx_data_frag(struct nci_dev *ndev,
215				 struct sk_buff *skb,
216				 __u8 pbf, __u8 conn_id, __u8 status)
217{
218	int reassembly_len;
219	int err = 0;
220
221	if (status) {
222		err = status;
223		goto exit;
224	}
225
226	if (ndev->rx_data_reassembly) {
227		reassembly_len = ndev->rx_data_reassembly->len;
228
229		/* first, make enough room for the already accumulated data */
230		if (skb_cow_head(skb, reassembly_len)) {
231			pr_err("error adding room for accumulated rx data\n");
232
233			kfree_skb(skb);
234			skb = NULL;
235
236			kfree_skb(ndev->rx_data_reassembly);
237			ndev->rx_data_reassembly = NULL;
238
239			err = -ENOMEM;
240			goto exit;
241		}
242
243		/* second, combine the two fragments */
244		memcpy(skb_push(skb, reassembly_len),
245		       ndev->rx_data_reassembly->data,
246		       reassembly_len);
247
248		/* third, free old reassembly */
249		kfree_skb(ndev->rx_data_reassembly);
250		ndev->rx_data_reassembly = NULL;
251	}
252
253	if (pbf == NCI_PBF_CONT) {
254		/* need to wait for next fragment, store skb and exit */
255		ndev->rx_data_reassembly = skb;
256		return;
257	}
258
259exit:
260	if (ndev->nfc_dev->rf_mode == NFC_RF_TARGET) {
261		/* Data received in Target mode, forward to nfc core */
262		err = nfc_tm_data_received(ndev->nfc_dev, skb);
263		if (err)
264			pr_err("unable to handle received data\n");
265	} else {
266		nci_data_exchange_complete(ndev, skb, conn_id, err);
267	}
268}
269
270/* Rx Data packet */
271void nci_rx_data_packet(struct nci_dev *ndev, struct sk_buff *skb)
272{
273	__u8 pbf = nci_pbf(skb->data);
274	__u8 status = 0;
275	__u8 conn_id = nci_conn_id(skb->data);
276	const struct nci_conn_info *conn_info;
277
278	pr_debug("len %d\n", skb->len);
279
280	pr_debug("NCI RX: MT=data, PBF=%d, conn_id=%d, plen=%d\n",
281		 nci_pbf(skb->data),
282		 nci_conn_id(skb->data),
283		 nci_plen(skb->data));
284
285	conn_info = nci_get_conn_info_by_conn_id(ndev, nci_conn_id(skb->data));
286	if (!conn_info) {
287		kfree_skb(skb);
288		return;
289	}
290
291	/* strip the nci data header */
292	skb_pull(skb, NCI_DATA_HDR_SIZE);
293
294	if (ndev->target_active_prot == NFC_PROTO_MIFARE ||
295	    ndev->target_active_prot == NFC_PROTO_JEWEL ||
296	    ndev->target_active_prot == NFC_PROTO_FELICA ||
297	    ndev->target_active_prot == NFC_PROTO_ISO15693) {
298		/* frame I/F => remove the status byte */
299		pr_debug("frame I/F => remove the status byte\n");
300		status = skb->data[skb->len - 1];
301		skb_trim(skb, (skb->len - 1));
302	}
303
304	nci_add_rx_data_frag(ndev, skb, pbf, conn_id, nci_to_errno(status));
305}