1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Low Level Transport (NDLC) Driver for STMicroelectronics NFC Chip
4  *
5  * Copyright (C) 2014-2015  STMicroelectronics SAS. All rights reserved.
6  */
7 
8 #include <linux/sched.h>
9 #include <net/nfc/nci_core.h>
10 
11 #include "st-nci.h"
12 
13 #define NDLC_TIMER_T1		100
14 #define NDLC_TIMER_T1_WAIT	400
15 #define NDLC_TIMER_T2		1200
16 
17 #define PCB_TYPE_DATAFRAME		0x80
18 #define PCB_TYPE_SUPERVISOR		0xc0
19 #define PCB_TYPE_MASK			PCB_TYPE_SUPERVISOR
20 
21 #define PCB_SYNC_ACK			0x20
22 #define PCB_SYNC_NACK			0x10
23 #define PCB_SYNC_WAIT			0x30
24 #define PCB_SYNC_NOINFO			0x00
25 #define PCB_SYNC_MASK			PCB_SYNC_WAIT
26 
27 #define PCB_DATAFRAME_RETRANSMIT_YES	0x00
28 #define PCB_DATAFRAME_RETRANSMIT_NO	0x04
29 #define PCB_DATAFRAME_RETRANSMIT_MASK	PCB_DATAFRAME_RETRANSMIT_NO
30 
31 #define PCB_SUPERVISOR_RETRANSMIT_YES	0x00
32 #define PCB_SUPERVISOR_RETRANSMIT_NO	0x02
33 #define PCB_SUPERVISOR_RETRANSMIT_MASK	PCB_SUPERVISOR_RETRANSMIT_NO
34 
35 #define PCB_FRAME_CRC_INFO_PRESENT	0x08
36 #define PCB_FRAME_CRC_INFO_NOTPRESENT	0x00
37 #define PCB_FRAME_CRC_INFO_MASK		PCB_FRAME_CRC_INFO_PRESENT
38 
39 #define NDLC_DUMP_SKB(info, skb)                                 \
40 do {                                                             \
41 	pr_debug("%s:\n", info);                                 \
42 	print_hex_dump(KERN_DEBUG, "ndlc: ", DUMP_PREFIX_OFFSET, \
43 			16, 1, skb->data, skb->len, 0);          \
44 } while (0)
45 
ndlc_open(struct llt_ndlc * ndlc)46 int ndlc_open(struct llt_ndlc *ndlc)
47 {
48 	/* toggle reset pin */
49 	ndlc->ops->enable(ndlc->phy_id);
50 	ndlc->powered = 1;
51 	return 0;
52 }
53 EXPORT_SYMBOL(ndlc_open);
54 
ndlc_close(struct llt_ndlc * ndlc)55 void ndlc_close(struct llt_ndlc *ndlc)
56 {
57 	struct nci_mode_set_cmd cmd;
58 
59 	cmd.cmd_type = ST_NCI_SET_NFC_MODE;
60 	cmd.mode = 0;
61 
62 	/* toggle reset pin */
63 	ndlc->ops->enable(ndlc->phy_id);
64 
65 	nci_prop_cmd(ndlc->ndev, ST_NCI_CORE_PROP,
66 		     sizeof(struct nci_mode_set_cmd), (__u8 *)&cmd);
67 
68 	ndlc->powered = 0;
69 	ndlc->ops->disable(ndlc->phy_id);
70 }
71 EXPORT_SYMBOL(ndlc_close);
72 
ndlc_send(struct llt_ndlc * ndlc,struct sk_buff * skb)73 int 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 	*(u8 *)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 }
86 EXPORT_SYMBOL(ndlc_send);
87 
llt_ndlc_send_queue(struct llt_ndlc * ndlc)88 static 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 
llt_ndlc_requeue_data_pending(struct llt_ndlc * ndlc)122 static 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 
llt_ndlc_rcv_queue(struct llt_ndlc * ndlc)147 static 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 				skb = skb_dequeue(&ndlc->ack_pending_q);
163 				kfree_skb(skb);
164 				del_timer_sync(&ndlc->t1_timer);
165 				del_timer_sync(&ndlc->t2_timer);
166 				ndlc->t2_active = false;
167 				ndlc->t1_active = false;
168 				break;
169 			case PCB_SYNC_NACK:
170 				llt_ndlc_requeue_data_pending(ndlc);
171 				llt_ndlc_send_queue(ndlc);
172 				/* start timer t1 for ndlc aknowledge */
173 				time_sent = jiffies;
174 				ndlc->t1_active = true;
175 				mod_timer(&ndlc->t1_timer, time_sent +
176 					msecs_to_jiffies(NDLC_TIMER_T1));
177 				break;
178 			case PCB_SYNC_WAIT:
179 				time_sent = jiffies;
180 				ndlc->t1_active = true;
181 				mod_timer(&ndlc->t1_timer, time_sent +
182 					  msecs_to_jiffies(NDLC_TIMER_T1_WAIT));
183 				break;
184 			default:
185 				kfree_skb(skb);
186 				break;
187 			}
188 		} else if ((pcb & PCB_TYPE_MASK) == PCB_TYPE_DATAFRAME) {
189 			nci_recv_frame(ndlc->ndev, skb);
190 		} else {
191 			kfree_skb(skb);
192 		}
193 	}
194 }
195 
llt_ndlc_sm_work(struct work_struct * work)196 static void llt_ndlc_sm_work(struct work_struct *work)
197 {
198 	struct llt_ndlc *ndlc = container_of(work, struct llt_ndlc, sm_work);
199 
200 	llt_ndlc_send_queue(ndlc);
201 	llt_ndlc_rcv_queue(ndlc);
202 
203 	if (ndlc->t1_active && timer_pending(&ndlc->t1_timer) == 0) {
204 		pr_debug
205 		    ("Handle T1(recv SUPERVISOR) elapsed (T1 now inactive)\n");
206 		ndlc->t1_active = false;
207 
208 		llt_ndlc_requeue_data_pending(ndlc);
209 		llt_ndlc_send_queue(ndlc);
210 	}
211 
212 	if (ndlc->t2_active && timer_pending(&ndlc->t2_timer) == 0) {
213 		pr_debug("Handle T2(recv DATA) elapsed (T2 now inactive)\n");
214 		ndlc->t2_active = false;
215 		ndlc->t1_active = false;
216 		del_timer_sync(&ndlc->t1_timer);
217 		del_timer_sync(&ndlc->t2_timer);
218 		ndlc_close(ndlc);
219 		ndlc->hard_fault = -EREMOTEIO;
220 	}
221 }
222 
ndlc_recv(struct llt_ndlc * ndlc,struct sk_buff * skb)223 void ndlc_recv(struct llt_ndlc *ndlc, struct sk_buff *skb)
224 {
225 	if (skb == NULL) {
226 		pr_err("NULL Frame -> link is dead\n");
227 		ndlc->hard_fault = -EREMOTEIO;
228 		ndlc_close(ndlc);
229 	} else {
230 		NDLC_DUMP_SKB("incoming frame", skb);
231 		skb_queue_tail(&ndlc->rcv_q, skb);
232 	}
233 
234 	schedule_work(&ndlc->sm_work);
235 }
236 EXPORT_SYMBOL(ndlc_recv);
237 
ndlc_t1_timeout(struct timer_list * t)238 static void ndlc_t1_timeout(struct timer_list *t)
239 {
240 	struct llt_ndlc *ndlc = from_timer(ndlc, t, t1_timer);
241 
242 	schedule_work(&ndlc->sm_work);
243 }
244 
ndlc_t2_timeout(struct timer_list * t)245 static void ndlc_t2_timeout(struct timer_list *t)
246 {
247 	struct llt_ndlc *ndlc = from_timer(ndlc, t, t2_timer);
248 
249 	schedule_work(&ndlc->sm_work);
250 }
251 
ndlc_probe(void * phy_id,const struct nfc_phy_ops * phy_ops,struct device * dev,int phy_headroom,int phy_tailroom,struct llt_ndlc ** ndlc_id,struct st_nci_se_status * se_status)252 int ndlc_probe(void *phy_id, const struct nfc_phy_ops *phy_ops,
253 	       struct device *dev, int phy_headroom, int phy_tailroom,
254 	       struct llt_ndlc **ndlc_id, struct st_nci_se_status *se_status)
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 	ndlc->powered = 0;
266 
267 	*ndlc_id = ndlc;
268 
269 	/* initialize timers */
270 	timer_setup(&ndlc->t1_timer, ndlc_t1_timeout, 0);
271 	timer_setup(&ndlc->t2_timer, ndlc_t2_timeout, 0);
272 
273 	skb_queue_head_init(&ndlc->rcv_q);
274 	skb_queue_head_init(&ndlc->send_q);
275 	skb_queue_head_init(&ndlc->ack_pending_q);
276 
277 	INIT_WORK(&ndlc->sm_work, llt_ndlc_sm_work);
278 
279 	return st_nci_probe(ndlc, phy_headroom, phy_tailroom, se_status);
280 }
281 EXPORT_SYMBOL(ndlc_probe);
282 
ndlc_remove(struct llt_ndlc * ndlc)283 void ndlc_remove(struct llt_ndlc *ndlc)
284 {
285 	st_nci_remove(ndlc->ndev);
286 
287 	/* cancel timers */
288 	del_timer_sync(&ndlc->t1_timer);
289 	del_timer_sync(&ndlc->t2_timer);
290 	ndlc->t2_active = false;
291 	ndlc->t1_active = false;
292 
293 	skb_queue_purge(&ndlc->rcv_q);
294 	skb_queue_purge(&ndlc->send_q);
295 }
296 EXPORT_SYMBOL(ndlc_remove);
297