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, struct sk_buff *skb, 39 int err) 40 { 41 data_exchange_cb_t cb = ndev->data_exchange_cb; 42 void *cb_context = ndev->data_exchange_cb_context; 43 44 pr_debug("len %d, err %d\n", skb ? skb->len : 0, err); 45 46 /* data exchange is complete, stop the data timer */ 47 del_timer_sync(&ndev->data_timer); 48 clear_bit(NCI_DATA_EXCHANGE_TO, &ndev->flags); 49 50 if (cb) { 51 ndev->data_exchange_cb = NULL; 52 ndev->data_exchange_cb_context = NULL; 53 54 /* forward skb to nfc core */ 55 cb(cb_context, skb, err); 56 } else if (skb) { 57 pr_err("no rx callback, dropping rx data...\n"); 58 59 /* no waiting callback, free skb */ 60 kfree_skb(skb); 61 } 62 63 clear_bit(NCI_DATA_EXCHANGE, &ndev->flags); 64 } 65 66 /* ----------------- NCI TX Data ----------------- */ 67 68 static 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 = (struct nci_data_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 85 static int nci_queue_tx_data_frags(struct nci_dev *ndev, 86 __u8 conn_id, 87 struct sk_buff *skb) { 88 int total_len = skb->len; 89 unsigned char *data = skb->data; 90 unsigned long flags; 91 struct sk_buff_head frags_q; 92 struct sk_buff *skb_frag; 93 int frag_len; 94 int rc = 0; 95 96 pr_debug("conn_id 0x%x, total_len %d\n", conn_id, total_len); 97 98 __skb_queue_head_init(&frags_q); 99 100 while (total_len) { 101 frag_len = 102 min_t(int, total_len, ndev->max_data_pkt_payload_size); 103 104 skb_frag = nci_skb_alloc(ndev, 105 (NCI_DATA_HDR_SIZE + frag_len), 106 GFP_KERNEL); 107 if (skb_frag == NULL) { 108 rc = -ENOMEM; 109 goto free_exit; 110 } 111 skb_reserve(skb_frag, NCI_DATA_HDR_SIZE); 112 113 /* first, copy the data */ 114 memcpy(skb_put(skb_frag, frag_len), data, frag_len); 115 116 /* second, set the header */ 117 nci_push_data_hdr(ndev, conn_id, skb_frag, 118 ((total_len == frag_len) ? 119 (NCI_PBF_LAST) : (NCI_PBF_CONT))); 120 121 __skb_queue_tail(&frags_q, skb_frag); 122 123 data += frag_len; 124 total_len -= frag_len; 125 126 pr_debug("frag_len %d, remaining total_len %d\n", 127 frag_len, total_len); 128 } 129 130 /* queue all fragments atomically */ 131 spin_lock_irqsave(&ndev->tx_q.lock, flags); 132 133 while ((skb_frag = __skb_dequeue(&frags_q)) != NULL) 134 __skb_queue_tail(&ndev->tx_q, skb_frag); 135 136 spin_unlock_irqrestore(&ndev->tx_q.lock, flags); 137 138 /* free the original skb */ 139 kfree_skb(skb); 140 141 goto exit; 142 143 free_exit: 144 while ((skb_frag = __skb_dequeue(&frags_q)) != NULL) 145 kfree_skb(skb_frag); 146 147 exit: 148 return rc; 149 } 150 151 /* Send NCI data */ 152 int nci_send_data(struct nci_dev *ndev, __u8 conn_id, struct sk_buff *skb) 153 { 154 int rc = 0; 155 156 pr_debug("conn_id 0x%x, plen %d\n", conn_id, skb->len); 157 158 /* check if the packet need to be fragmented */ 159 if (skb->len <= ndev->max_data_pkt_payload_size) { 160 /* no need to fragment packet */ 161 nci_push_data_hdr(ndev, conn_id, skb, NCI_PBF_LAST); 162 163 skb_queue_tail(&ndev->tx_q, skb); 164 } else { 165 /* fragment packet and queue the fragments */ 166 rc = nci_queue_tx_data_frags(ndev, conn_id, skb); 167 if (rc) { 168 pr_err("failed to fragment tx data packet\n"); 169 goto free_exit; 170 } 171 } 172 173 queue_work(ndev->tx_wq, &ndev->tx_work); 174 175 goto exit; 176 177 free_exit: 178 kfree_skb(skb); 179 180 exit: 181 return rc; 182 } 183 184 /* ----------------- NCI RX Data ----------------- */ 185 186 static void nci_add_rx_data_frag(struct nci_dev *ndev, 187 struct sk_buff *skb, 188 __u8 pbf) 189 { 190 int reassembly_len; 191 int err = 0; 192 193 if (ndev->rx_data_reassembly) { 194 reassembly_len = ndev->rx_data_reassembly->len; 195 196 /* first, make enough room for the already accumulated data */ 197 if (skb_cow_head(skb, reassembly_len)) { 198 pr_err("error adding room for accumulated rx data\n"); 199 200 kfree_skb(skb); 201 skb = NULL; 202 203 kfree_skb(ndev->rx_data_reassembly); 204 ndev->rx_data_reassembly = NULL; 205 206 err = -ENOMEM; 207 goto exit; 208 } 209 210 /* second, combine the two fragments */ 211 memcpy(skb_push(skb, reassembly_len), 212 ndev->rx_data_reassembly->data, 213 reassembly_len); 214 215 /* third, free old reassembly */ 216 kfree_skb(ndev->rx_data_reassembly); 217 ndev->rx_data_reassembly = NULL; 218 } 219 220 if (pbf == NCI_PBF_CONT) { 221 /* need to wait for next fragment, store skb and exit */ 222 ndev->rx_data_reassembly = skb; 223 return; 224 } 225 226 exit: 227 nci_data_exchange_complete(ndev, skb, err); 228 } 229 230 /* Rx Data packet */ 231 void nci_rx_data_packet(struct nci_dev *ndev, struct sk_buff *skb) 232 { 233 __u8 pbf = nci_pbf(skb->data); 234 235 pr_debug("len %d\n", skb->len); 236 237 pr_debug("NCI RX: MT=data, PBF=%d, conn_id=%d, plen=%d\n", 238 nci_pbf(skb->data), 239 nci_conn_id(skb->data), 240 nci_plen(skb->data)); 241 242 /* strip the nci data header */ 243 skb_pull(skb, NCI_DATA_HDR_SIZE); 244 245 if (ndev->target_active_prot == NFC_PROTO_MIFARE) { 246 /* frame I/F => remove the status byte */ 247 pr_debug("NFC_PROTO_MIFARE => remove the status byte\n"); 248 skb_trim(skb, (skb->len - 1)); 249 } 250 251 nci_add_rx_data_frag(ndev, skb, pbf); 252 } 253