kernel/drivers/nfc/st21nfcb/ndlc.c

   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)                                 \
  52 do {                                                             \
  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
  58 int ndlc_open(struct llt_ndlc *ndlc)
  59 {
  60         /* toggle reset pin */
  61         ndlc->ops->enable(ndlc->phy_id);
  62         return 0;
  63 }
  64 EXPORT_SYMBOL(ndlc_open);
  65
  66 void ndlc_close(struct llt_ndlc *ndlc)
  67 {
  68         /* toggle reset pin */
  69         ndlc->ops->disable(ndlc->phy_id);
  70 }
  71 EXPORT_SYMBOL(ndlc_close);
  72
  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         *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
  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
 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
 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                                 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
 193 static 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
 220 void 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 }
 233 EXPORT_SYMBOL(ndlc_recv);
 234
 235 static 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
 244 static 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
 253 int 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 }
 285 EXPORT_SYMBOL(ndlc_probe);
 286
 287 void 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 }
 300 EXPORT_SYMBOL(ndlc_remove);