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, see <http://www.gnu.org/licenses/>. 20 * 21 */ 22 23 #define pr_fmt(fmt) KBUILD_MODNAME ": %s: " fmt, __func__ 24 25 #include <linux/types.h> 26 #include <linux/interrupt.h> 27 #include <linux/wait.h> 28 #include <linux/bitops.h> 29 #include <linux/skbuff.h> 30 31 #include "../nfc.h" 32 #include <net/nfc/nci.h> 33 #include <net/nfc/nci_core.h> 34 #include <linux/nfc.h> 35 36 /* Complete data exchange transaction and forward skb to nfc core */ 37 void nci_data_exchange_complete(struct nci_dev *ndev, struct sk_buff *skb, 38 int err) 39 { 40 data_exchange_cb_t cb = ndev->data_exchange_cb; 41 void *cb_context = ndev->data_exchange_cb_context; 42 43 pr_debug("len %d, err %d\n", skb ? skb->len : 0, err); 44 45 /* data exchange is complete, stop the data timer */ 46 del_timer_sync(&ndev->data_timer); 47 clear_bit(NCI_DATA_EXCHANGE_TO, &ndev->flags); 48 49 if (cb) { 50 ndev->data_exchange_cb = NULL; 51 ndev->data_exchange_cb_context = NULL; 52 53 /* forward skb to nfc core */ 54 cb(cb_context, skb, err); 55 } else if (skb) { 56 pr_err("no rx callback, dropping rx data...\n"); 57 58 /* no waiting callback, free skb */ 59 kfree_skb(skb); 60 } 61 62 clear_bit(NCI_DATA_EXCHANGE, &ndev->flags); 63 } 64 65 /* ----------------- NCI TX Data ----------------- */ 66 67 static inline void nci_push_data_hdr(struct nci_dev *ndev, 68 __u8 conn_id, 69 struct sk_buff *skb, 70 __u8 pbf) 71 { 72 struct nci_data_hdr *hdr; 73 int plen = skb->len; 74 75 hdr = (struct nci_data_hdr *) skb_push(skb, NCI_DATA_HDR_SIZE); 76 hdr->conn_id = conn_id; 77 hdr->rfu = 0; 78 hdr->plen = plen; 79 80 nci_mt_set((__u8 *)hdr, NCI_MT_DATA_PKT); 81 nci_pbf_set((__u8 *)hdr, pbf); 82 } 83 84 static int nci_queue_tx_data_frags(struct nci_dev *ndev, 85 __u8 conn_id, 86 struct sk_buff *skb) { 87 int total_len = skb->len; 88 unsigned char *data = skb->data; 89 unsigned long flags; 90 struct sk_buff_head frags_q; 91 struct sk_buff *skb_frag; 92 int frag_len; 93 int rc = 0; 94 95 pr_debug("conn_id 0x%x, total_len %d\n", conn_id, total_len); 96 97 __skb_queue_head_init(&frags_q); 98 99 while (total_len) { 100 frag_len = 101 min_t(int, total_len, ndev->max_data_pkt_payload_size); 102 103 skb_frag = nci_skb_alloc(ndev, 104 (NCI_DATA_HDR_SIZE + frag_len), 105 GFP_KERNEL); 106 if (skb_frag == NULL) { 107 rc = -ENOMEM; 108 goto free_exit; 109 } 110 skb_reserve(skb_frag, NCI_DATA_HDR_SIZE); 111 112 /* first, copy the data */ 113 memcpy(skb_put(skb_frag, frag_len), data, frag_len); 114 115 /* second, set the header */ 116 nci_push_data_hdr(ndev, conn_id, skb_frag, 117 ((total_len == frag_len) ? 118 (NCI_PBF_LAST) : (NCI_PBF_CONT))); 119 120 __skb_queue_tail(&frags_q, skb_frag); 121 122 data += frag_len; 123 total_len -= frag_len; 124 125 pr_debug("frag_len %d, remaining total_len %d\n", 126 frag_len, total_len); 127 } 128 129 /* queue all fragments atomically */ 130 spin_lock_irqsave(&ndev->tx_q.lock, flags); 131 132 while ((skb_frag = __skb_dequeue(&frags_q)) != NULL) 133 __skb_queue_tail(&ndev->tx_q, skb_frag); 134 135 spin_unlock_irqrestore(&ndev->tx_q.lock, flags); 136 137 /* free the original skb */ 138 kfree_skb(skb); 139 140 goto exit; 141 142 free_exit: 143 while ((skb_frag = __skb_dequeue(&frags_q)) != NULL) 144 kfree_skb(skb_frag); 145 146 exit: 147 return rc; 148 } 149 150 /* Send NCI data */ 151 int nci_send_data(struct nci_dev *ndev, __u8 conn_id, struct sk_buff *skb) 152 { 153 int rc = 0; 154 155 pr_debug("conn_id 0x%x, plen %d\n", conn_id, skb->len); 156 157 /* check if the packet need to be fragmented */ 158 if (skb->len <= ndev->max_data_pkt_payload_size) { 159 /* no need to fragment packet */ 160 nci_push_data_hdr(ndev, conn_id, skb, NCI_PBF_LAST); 161 162 skb_queue_tail(&ndev->tx_q, skb); 163 } else { 164 /* fragment packet and queue the fragments */ 165 rc = nci_queue_tx_data_frags(ndev, conn_id, skb); 166 if (rc) { 167 pr_err("failed to fragment tx data packet\n"); 168 goto free_exit; 169 } 170 } 171 172 queue_work(ndev->tx_wq, &ndev->tx_work); 173 174 goto exit; 175 176 free_exit: 177 kfree_skb(skb); 178 179 exit: 180 return rc; 181 } 182 183 /* ----------------- NCI RX Data ----------------- */ 184 185 static void nci_add_rx_data_frag(struct nci_dev *ndev, 186 struct sk_buff *skb, 187 __u8 pbf) 188 { 189 int reassembly_len; 190 int err = 0; 191 192 if (ndev->rx_data_reassembly) { 193 reassembly_len = ndev->rx_data_reassembly->len; 194 195 /* first, make enough room for the already accumulated data */ 196 if (skb_cow_head(skb, reassembly_len)) { 197 pr_err("error adding room for accumulated rx data\n"); 198 199 kfree_skb(skb); 200 skb = NULL; 201 202 kfree_skb(ndev->rx_data_reassembly); 203 ndev->rx_data_reassembly = NULL; 204 205 err = -ENOMEM; 206 goto exit; 207 } 208 209 /* second, combine the two fragments */ 210 memcpy(skb_push(skb, reassembly_len), 211 ndev->rx_data_reassembly->data, 212 reassembly_len); 213 214 /* third, free old reassembly */ 215 kfree_skb(ndev->rx_data_reassembly); 216 ndev->rx_data_reassembly = NULL; 217 } 218 219 if (pbf == NCI_PBF_CONT) { 220 /* need to wait for next fragment, store skb and exit */ 221 ndev->rx_data_reassembly = skb; 222 return; 223 } 224 225 exit: 226 nci_data_exchange_complete(ndev, skb, err); 227 } 228 229 /* Rx Data packet */ 230 void nci_rx_data_packet(struct nci_dev *ndev, struct sk_buff *skb) 231 { 232 __u8 pbf = nci_pbf(skb->data); 233 234 pr_debug("len %d\n", skb->len); 235 236 pr_debug("NCI RX: MT=data, PBF=%d, conn_id=%d, plen=%d\n", 237 nci_pbf(skb->data), 238 nci_conn_id(skb->data), 239 nci_plen(skb->data)); 240 241 /* strip the nci data header */ 242 skb_pull(skb, NCI_DATA_HDR_SIZE); 243 244 if (ndev->target_active_prot == NFC_PROTO_MIFARE) { 245 /* frame I/F => remove the status byte */ 246 pr_debug("NFC_PROTO_MIFARE => remove the status byte\n"); 247 skb_trim(skb, (skb->len - 1)); 248 } 249 250 nci_add_rx_data_frag(ndev, skb, pbf); 251 } 252