1/*
2 * Low Level Transport (NDLC) Driver for STMicroelectronics NFC Chip
3 *
4 * Copyright (C) 2014  STMicroelectronics SAS. All rights reserved.
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms and conditions of the GNU General Public License,
8 * version 2, as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, see <http://www.gnu.org/licenses/>.
17 */
18
19#include <linux/sched.h>
20#include <net/nfc/nci_core.h>
21
22#include "ndlc.h"
23#include "st21nfcb.h"
24
25#define NDLC_TIMER_T1		100
26#define NDLC_TIMER_T1_WAIT	400
27#define NDLC_TIMER_T2		1200
28
29#define PCB_TYPE_DATAFRAME		0x80
30#define PCB_TYPE_SUPERVISOR		0xc0
31#define PCB_TYPE_MASK			PCB_TYPE_SUPERVISOR
32
33#define PCB_SYNC_ACK			0x20
34#define PCB_SYNC_NACK			0x10
35#define PCB_SYNC_WAIT			0x30
36#define PCB_SYNC_NOINFO			0x00
37#define PCB_SYNC_MASK			PCB_SYNC_WAIT
38
39#define PCB_DATAFRAME_RETRANSMIT_YES	0x00
40#define PCB_DATAFRAME_RETRANSMIT_NO	0x04
41#define PCB_DATAFRAME_RETRANSMIT_MASK	PCB_DATAFRAME_RETRANSMIT_NO
42
43#define PCB_SUPERVISOR_RETRANSMIT_YES	0x00
44#define PCB_SUPERVISOR_RETRANSMIT_NO	0x02
45#define PCB_SUPERVISOR_RETRANSMIT_MASK	PCB_SUPERVISOR_RETRANSMIT_NO
46
47#define PCB_FRAME_CRC_INFO_PRESENT	0x08
48#define PCB_FRAME_CRC_INFO_NOTPRESENT	0x00
49#define PCB_FRAME_CRC_INFO_MASK		PCB_FRAME_CRC_INFO_PRESENT
50
51#define NDLC_DUMP_SKB(info, skb)                                 \
52do {                                                             \
53	pr_debug("%s:\n", info);                                 \
54	print_hex_dump(KERN_DEBUG, "ndlc: ", DUMP_PREFIX_OFFSET, \
55			16, 1, skb->data, skb->len, 0);          \
56} while (0)
57
58int ndlc_open(struct llt_ndlc *ndlc)
59{
60	/* toggle reset pin */
61	ndlc->ops->enable(ndlc->phy_id);
62	return 0;
63}
64EXPORT_SYMBOL(ndlc_open);
65
66void ndlc_close(struct llt_ndlc *ndlc)
67{
68	/* toggle reset pin */
69	ndlc->ops->disable(ndlc->phy_id);
70}
71EXPORT_SYMBOL(ndlc_close);
72
73int ndlc_send(struct llt_ndlc *ndlc, struct sk_buff *skb)
74{
75	/* add ndlc header */
76	u8 pcb = PCB_TYPE_DATAFRAME | PCB_DATAFRAME_RETRANSMIT_NO |
77		PCB_FRAME_CRC_INFO_NOTPRESENT;
78
79	*skb_push(skb, 1) = pcb;
80	skb_queue_tail(&ndlc->send_q, skb);
81
82	schedule_work(&ndlc->sm_work);
83
84	return 0;
85}
86EXPORT_SYMBOL(ndlc_send);
87
88static void llt_ndlc_send_queue(struct llt_ndlc *ndlc)
89{
90	struct sk_buff *skb;
91	int r;
92	unsigned long time_sent;
93
94	if (ndlc->send_q.qlen)
95		pr_debug("sendQlen=%d unackQlen=%d\n",
96			 ndlc->send_q.qlen, ndlc->ack_pending_q.qlen);
97
98	while (ndlc->send_q.qlen) {
99		skb = skb_dequeue(&ndlc->send_q);
100		NDLC_DUMP_SKB("ndlc frame written", skb);
101		r = ndlc->ops->write(ndlc->phy_id, skb);
102		if (r < 0) {
103			ndlc->hard_fault = r;
104			break;
105		}
106		time_sent = jiffies;
107		*(unsigned long *)skb->cb = time_sent;
108
109		skb_queue_tail(&ndlc->ack_pending_q, skb);
110
111		/* start timer t1 for ndlc aknowledge */
112		ndlc->t1_active = true;
113		mod_timer(&ndlc->t1_timer, time_sent +
114			msecs_to_jiffies(NDLC_TIMER_T1));
115		/* start timer t2 for chip availability */
116		ndlc->t2_active = true;
117		mod_timer(&ndlc->t2_timer, time_sent +
118			msecs_to_jiffies(NDLC_TIMER_T2));
119	}
120}
121
122static void llt_ndlc_requeue_data_pending(struct llt_ndlc *ndlc)
123{
124	struct sk_buff *skb;
125	u8 pcb;
126
127	while ((skb = skb_dequeue_tail(&ndlc->ack_pending_q))) {
128		pcb = skb->data[0];
129		switch (pcb & PCB_TYPE_MASK) {
130		case PCB_TYPE_SUPERVISOR:
131			skb->data[0] = (pcb & ~PCB_SUPERVISOR_RETRANSMIT_MASK) |
132				PCB_SUPERVISOR_RETRANSMIT_YES;
133			break;
134		case PCB_TYPE_DATAFRAME:
135			skb->data[0] = (pcb & ~PCB_DATAFRAME_RETRANSMIT_MASK) |
136				PCB_DATAFRAME_RETRANSMIT_YES;
137			break;
138		default:
139			pr_err("UNKNOWN Packet Control Byte=%d\n", pcb);
140			kfree_skb(skb);
141			continue;
142		}
143		skb_queue_head(&ndlc->send_q, skb);
144	}
145}
146
147static void llt_ndlc_rcv_queue(struct llt_ndlc *ndlc)
148{
149	struct sk_buff *skb;
150	u8 pcb;
151	unsigned long time_sent;
152
153	if (ndlc->rcv_q.qlen)
154		pr_debug("rcvQlen=%d\n", ndlc->rcv_q.qlen);
155
156	while ((skb = skb_dequeue(&ndlc->rcv_q)) != NULL) {
157		pcb = skb->data[0];
158		skb_pull(skb, 1);
159		if ((pcb & PCB_TYPE_MASK) == PCB_TYPE_SUPERVISOR) {
160			switch (pcb & PCB_SYNC_MASK) {
161			case PCB_SYNC_ACK:
162				del_timer_sync(&ndlc->t1_timer);
163				del_timer_sync(&ndlc->t2_timer);
164				ndlc->t2_active = false;
165				ndlc->t1_active = false;
166				break;
167			case PCB_SYNC_NACK:
168				llt_ndlc_requeue_data_pending(ndlc);
169				llt_ndlc_send_queue(ndlc);
170				/* start timer t1 for ndlc aknowledge */
171				time_sent = jiffies;
172				ndlc->t1_active = true;
173				mod_timer(&ndlc->t1_timer, time_sent +
174					msecs_to_jiffies(NDLC_TIMER_T1));
175				break;
176			case PCB_SYNC_WAIT:
177				time_sent = jiffies;
178				ndlc->t1_active = true;
179				mod_timer(&ndlc->t1_timer, time_sent +
180					  msecs_to_jiffies(NDLC_TIMER_T1_WAIT));
181				break;
182			default:
183				pr_err("UNKNOWN Packet Control Byte=%d\n", pcb);
184				kfree_skb(skb);
185				break;
186			}
187		} else {
188			nci_recv_frame(ndlc->ndev, skb);
189		}
190	}
191}
192
193static void llt_ndlc_sm_work(struct work_struct *work)
194{
195	struct llt_ndlc *ndlc = container_of(work, struct llt_ndlc, sm_work);
196
197	llt_ndlc_send_queue(ndlc);
198	llt_ndlc_rcv_queue(ndlc);
199
200	if (ndlc->t1_active && timer_pending(&ndlc->t1_timer) == 0) {
201		pr_debug
202		    ("Handle T1(recv SUPERVISOR) elapsed (T1 now inactive)\n");
203		ndlc->t1_active = false;
204
205		llt_ndlc_requeue_data_pending(ndlc);
206		llt_ndlc_send_queue(ndlc);
207	}
208
209	if (ndlc->t2_active && timer_pending(&ndlc->t2_timer) == 0) {
210		pr_debug("Handle T2(recv DATA) elapsed (T2 now inactive)\n");
211		ndlc->t2_active = false;
212		ndlc->t1_active = false;
213		del_timer_sync(&ndlc->t1_timer);
214		del_timer_sync(&ndlc->t2_timer);
215		ndlc_close(ndlc);
216		ndlc->hard_fault = -EREMOTEIO;
217	}
218}
219
220void ndlc_recv(struct llt_ndlc *ndlc, struct sk_buff *skb)
221{
222	if (skb == NULL) {
223		pr_err("NULL Frame -> link is dead\n");
224		ndlc->hard_fault = -EREMOTEIO;
225		ndlc_close(ndlc);
226	} else {
227		NDLC_DUMP_SKB("incoming frame", skb);
228		skb_queue_tail(&ndlc->rcv_q, skb);
229	}
230
231	schedule_work(&ndlc->sm_work);
232}
233EXPORT_SYMBOL(ndlc_recv);
234
235static void ndlc_t1_timeout(unsigned long data)
236{
237	struct llt_ndlc *ndlc = (struct llt_ndlc *)data;
238
239	pr_debug("\n");
240
241	schedule_work(&ndlc->sm_work);
242}
243
244static void ndlc_t2_timeout(unsigned long data)
245{
246	struct llt_ndlc *ndlc = (struct llt_ndlc *)data;
247
248	pr_debug("\n");
249
250	schedule_work(&ndlc->sm_work);
251}
252
253int ndlc_probe(void *phy_id, struct nfc_phy_ops *phy_ops, struct device *dev,
254	       int phy_headroom, int phy_tailroom, struct llt_ndlc **ndlc_id)
255{
256	struct llt_ndlc *ndlc;
257
258	ndlc = devm_kzalloc(dev, sizeof(struct llt_ndlc), GFP_KERNEL);
259	if (!ndlc)
260		return -ENOMEM;
261
262	ndlc->ops = phy_ops;
263	ndlc->phy_id = phy_id;
264	ndlc->dev = dev;
265
266	*ndlc_id = ndlc;
267
268	/* initialize timers */
269	init_timer(&ndlc->t1_timer);
270	ndlc->t1_timer.data = (unsigned long)ndlc;
271	ndlc->t1_timer.function = ndlc_t1_timeout;
272
273	init_timer(&ndlc->t2_timer);
274	ndlc->t2_timer.data = (unsigned long)ndlc;
275	ndlc->t2_timer.function = ndlc_t2_timeout;
276
277	skb_queue_head_init(&ndlc->rcv_q);
278	skb_queue_head_init(&ndlc->send_q);
279	skb_queue_head_init(&ndlc->ack_pending_q);
280
281	INIT_WORK(&ndlc->sm_work, llt_ndlc_sm_work);
282
283	return st21nfcb_nci_probe(ndlc, phy_headroom, phy_tailroom);
284}
285EXPORT_SYMBOL(ndlc_probe);
286
287void ndlc_remove(struct llt_ndlc *ndlc)
288{
289	/* cancel timers */
290	del_timer_sync(&ndlc->t1_timer);
291	del_timer_sync(&ndlc->t2_timer);
292	ndlc->t2_active = false;
293	ndlc->t1_active = false;
294
295	skb_queue_purge(&ndlc->rcv_q);
296	skb_queue_purge(&ndlc->send_q);
297
298	st21nfcb_nci_remove(ndlc->ndev);
299}
300EXPORT_SYMBOL(ndlc_remove);
301