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 * 7 * Written by Ilan Elias <ilane@ti.com> 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License version 2 11 * as published by the Free Software Foundation 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 * 18 * You should have received a copy of the GNU General Public License 19 * along with this program; if not, write to the Free Software 20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 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 */ 38 void nci_data_exchange_complete(struct nci_dev *ndev, 39 struct sk_buff *skb, 40 int err) 41 { 42 data_exchange_cb_t cb = ndev->data_exchange_cb; 43 void *cb_context = ndev->data_exchange_cb_context; 44 45 pr_debug("len %d, err %d\n", skb ? skb->len : 0, err); 46 47 /* data exchange is complete, stop the data timer */ 48 del_timer_sync(&ndev->data_timer); 49 clear_bit(NCI_DATA_EXCHANGE_TO, &ndev->flags); 50 51 if (cb) { 52 ndev->data_exchange_cb = NULL; 53 ndev->data_exchange_cb_context = 0; 54 55 /* forward skb to nfc core */ 56 cb(cb_context, skb, err); 57 } else if (skb) { 58 pr_err("no rx callback, dropping rx data...\n"); 59 60 /* no waiting callback, free skb */ 61 kfree_skb(skb); 62 } 63 64 clear_bit(NCI_DATA_EXCHANGE, &ndev->flags); 65 } 66 67 /* ----------------- NCI TX Data ----------------- */ 68 69 static inline void nci_push_data_hdr(struct nci_dev *ndev, 70 __u8 conn_id, 71 struct sk_buff *skb, 72 __u8 pbf) 73 { 74 struct nci_data_hdr *hdr; 75 int plen = skb->len; 76 77 hdr = (struct nci_data_hdr *) skb_push(skb, NCI_DATA_HDR_SIZE); 78 hdr->conn_id = conn_id; 79 hdr->rfu = 0; 80 hdr->plen = plen; 81 82 nci_mt_set((__u8 *)hdr, NCI_MT_DATA_PKT); 83 nci_pbf_set((__u8 *)hdr, pbf); 84 85 skb->dev = (void *) ndev; 86 } 87 88 static int nci_queue_tx_data_frags(struct nci_dev *ndev, 89 __u8 conn_id, 90 struct sk_buff *skb) { 91 int total_len = skb->len; 92 unsigned char *data = skb->data; 93 unsigned long flags; 94 struct sk_buff_head frags_q; 95 struct sk_buff *skb_frag; 96 int frag_len; 97 int rc = 0; 98 99 pr_debug("conn_id 0x%x, total_len %d\n", conn_id, total_len); 100 101 __skb_queue_head_init(&frags_q); 102 103 while (total_len) { 104 frag_len = 105 min_t(int, total_len, ndev->max_data_pkt_payload_size); 106 107 skb_frag = nci_skb_alloc(ndev, 108 (NCI_DATA_HDR_SIZE + frag_len), 109 GFP_KERNEL); 110 if (skb_frag == NULL) { 111 rc = -ENOMEM; 112 goto free_exit; 113 } 114 skb_reserve(skb_frag, NCI_DATA_HDR_SIZE); 115 116 /* first, copy the data */ 117 memcpy(skb_put(skb_frag, frag_len), data, frag_len); 118 119 /* second, set the header */ 120 nci_push_data_hdr(ndev, conn_id, skb_frag, 121 ((total_len == frag_len) ? (NCI_PBF_LAST) : (NCI_PBF_CONT))); 122 123 __skb_queue_tail(&frags_q, skb_frag); 124 125 data += frag_len; 126 total_len -= frag_len; 127 128 pr_debug("frag_len %d, remaining total_len %d\n", 129 frag_len, total_len); 130 } 131 132 /* queue all fragments atomically */ 133 spin_lock_irqsave(&ndev->tx_q.lock, flags); 134 135 while ((skb_frag = __skb_dequeue(&frags_q)) != NULL) 136 __skb_queue_tail(&ndev->tx_q, skb_frag); 137 138 spin_unlock_irqrestore(&ndev->tx_q.lock, flags); 139 140 /* free the original skb */ 141 kfree_skb(skb); 142 143 goto exit; 144 145 free_exit: 146 while ((skb_frag = __skb_dequeue(&frags_q)) != NULL) 147 kfree_skb(skb_frag); 148 149 exit: 150 return rc; 151 } 152 153 /* Send NCI data */ 154 int nci_send_data(struct nci_dev *ndev, __u8 conn_id, struct sk_buff *skb) 155 { 156 int rc = 0; 157 158 pr_debug("conn_id 0x%x, plen %d\n", conn_id, skb->len); 159 160 /* check if the packet need to be fragmented */ 161 if (skb->len <= ndev->max_data_pkt_payload_size) { 162 /* no need to fragment packet */ 163 nci_push_data_hdr(ndev, conn_id, skb, NCI_PBF_LAST); 164 165 skb_queue_tail(&ndev->tx_q, skb); 166 } else { 167 /* fragment packet and queue the fragments */ 168 rc = nci_queue_tx_data_frags(ndev, conn_id, skb); 169 if (rc) { 170 pr_err("failed to fragment tx data packet\n"); 171 goto free_exit; 172 } 173 } 174 175 queue_work(ndev->tx_wq, &ndev->tx_work); 176 177 goto exit; 178 179 free_exit: 180 kfree_skb(skb); 181 182 exit: 183 return rc; 184 } 185 186 /* ----------------- NCI RX Data ----------------- */ 187 188 static void nci_add_rx_data_frag(struct nci_dev *ndev, 189 struct sk_buff *skb, 190 __u8 pbf) 191 { 192 int reassembly_len; 193 int err = 0; 194 195 if (ndev->rx_data_reassembly) { 196 reassembly_len = ndev->rx_data_reassembly->len; 197 198 /* first, make enough room for the already accumulated data */ 199 if (skb_cow_head(skb, reassembly_len)) { 200 pr_err("error adding room for accumulated rx data\n"); 201 202 kfree_skb(skb); 203 skb = 0; 204 205 kfree_skb(ndev->rx_data_reassembly); 206 ndev->rx_data_reassembly = 0; 207 208 err = -ENOMEM; 209 goto exit; 210 } 211 212 /* second, combine the two fragments */ 213 memcpy(skb_push(skb, reassembly_len), 214 ndev->rx_data_reassembly->data, 215 reassembly_len); 216 217 /* third, free old reassembly */ 218 kfree_skb(ndev->rx_data_reassembly); 219 ndev->rx_data_reassembly = 0; 220 } 221 222 if (pbf == NCI_PBF_CONT) { 223 /* need to wait for next fragment, store skb and exit */ 224 ndev->rx_data_reassembly = skb; 225 return; 226 } 227 228 exit: 229 nci_data_exchange_complete(ndev, skb, err); 230 } 231 232 /* Rx Data packet */ 233 void nci_rx_data_packet(struct nci_dev *ndev, struct sk_buff *skb) 234 { 235 __u8 pbf = nci_pbf(skb->data); 236 237 pr_debug("len %d\n", skb->len); 238 239 pr_debug("NCI RX: MT=data, PBF=%d, conn_id=%d, plen=%d\n", 240 nci_pbf(skb->data), 241 nci_conn_id(skb->data), 242 nci_plen(skb->data)); 243 244 /* strip the nci data header */ 245 skb_pull(skb, NCI_DATA_HDR_SIZE); 246 247 if (ndev->target_active_prot == NFC_PROTO_MIFARE) { 248 /* frame I/F => remove the status byte */ 249 pr_debug("NFC_PROTO_MIFARE => remove the status byte\n"); 250 skb_trim(skb, (skb->len - 1)); 251 } 252 253 nci_add_rx_data_frag(ndev, skb, pbf); 254 } 255