1 /* 2 * Copyright (C) 2013 Intel Corporation. All rights reserved. 3 * 4 * This program is free software; you can redistribute it and/or modify it 5 * under the terms and conditions of the GNU General Public License, 6 * version 2, as published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope it will be useful, but WITHOUT 9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 11 * more details. 12 * 13 * You should have received a copy of the GNU General Public License along with 14 * this program; if not, write to the Free Software Foundation, Inc., 15 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. 16 * 17 */ 18 19 #define pr_fmt(fmt) "nci_spi: %s: " fmt, __func__ 20 21 #include <linux/export.h> 22 #include <linux/spi/spi.h> 23 #include <linux/crc-ccitt.h> 24 #include <linux/nfc.h> 25 #include <net/nfc/nci_core.h> 26 27 #define NCI_SPI_HDR_LEN 4 28 #define NCI_SPI_CRC_LEN 2 29 #define NCI_SPI_ACK_SHIFT 6 30 #define NCI_SPI_MSB_PAYLOAD_MASK 0x3F 31 32 #define NCI_SPI_SEND_TIMEOUT (NCI_CMD_TIMEOUT > NCI_DATA_TIMEOUT ? \ 33 NCI_CMD_TIMEOUT : NCI_DATA_TIMEOUT) 34 35 #define NCI_SPI_DIRECT_WRITE 0x01 36 #define NCI_SPI_DIRECT_READ 0x02 37 38 #define ACKNOWLEDGE_NONE 0 39 #define ACKNOWLEDGE_ACK 1 40 #define ACKNOWLEDGE_NACK 2 41 42 #define CRC_INIT 0xFFFF 43 44 static int nci_spi_open(struct nci_dev *nci_dev) 45 { 46 struct nci_spi_dev *ndev = nci_get_drvdata(nci_dev); 47 48 return ndev->ops->open(ndev); 49 } 50 51 static int nci_spi_close(struct nci_dev *nci_dev) 52 { 53 struct nci_spi_dev *ndev = nci_get_drvdata(nci_dev); 54 55 return ndev->ops->close(ndev); 56 } 57 58 static int __nci_spi_send(struct nci_spi_dev *ndev, struct sk_buff *skb) 59 { 60 struct spi_message m; 61 struct spi_transfer t; 62 63 t.tx_buf = skb->data; 64 t.len = skb->len; 65 t.cs_change = 0; 66 t.delay_usecs = ndev->xfer_udelay; 67 68 spi_message_init(&m); 69 spi_message_add_tail(&t, &m); 70 71 return spi_sync(ndev->spi, &m); 72 } 73 74 static int nci_spi_send(struct nci_dev *nci_dev, struct sk_buff *skb) 75 { 76 struct nci_spi_dev *ndev = nci_get_drvdata(nci_dev); 77 unsigned int payload_len = skb->len; 78 unsigned char *hdr; 79 int ret; 80 long completion_rc; 81 82 ndev->ops->deassert_int(ndev); 83 84 /* add the NCI SPI header to the start of the buffer */ 85 hdr = skb_push(skb, NCI_SPI_HDR_LEN); 86 hdr[0] = NCI_SPI_DIRECT_WRITE; 87 hdr[1] = ndev->acknowledge_mode; 88 hdr[2] = payload_len >> 8; 89 hdr[3] = payload_len & 0xFF; 90 91 if (ndev->acknowledge_mode == NCI_SPI_CRC_ENABLED) { 92 u16 crc; 93 94 crc = crc_ccitt(CRC_INIT, skb->data, skb->len); 95 *skb_put(skb, 1) = crc >> 8; 96 *skb_put(skb, 1) = crc & 0xFF; 97 } 98 99 ret = __nci_spi_send(ndev, skb); 100 101 kfree_skb(skb); 102 ndev->ops->assert_int(ndev); 103 104 if (ret != 0 || ndev->acknowledge_mode == NCI_SPI_CRC_DISABLED) 105 goto done; 106 107 init_completion(&ndev->req_completion); 108 completion_rc = 109 wait_for_completion_interruptible_timeout(&ndev->req_completion, 110 NCI_SPI_SEND_TIMEOUT); 111 112 if (completion_rc <= 0 || ndev->req_result == ACKNOWLEDGE_NACK) 113 ret = -EIO; 114 115 done: 116 return ret; 117 } 118 119 static struct nci_ops nci_spi_ops = { 120 .open = nci_spi_open, 121 .close = nci_spi_close, 122 .send = nci_spi_send, 123 }; 124 125 /* ---- Interface to NCI SPI drivers ---- */ 126 127 /** 128 * nci_spi_allocate_device - allocate a new nci spi device 129 * 130 * @spi: SPI device 131 * @ops: device operations 132 * @supported_protocols: NFC protocols supported by the device 133 * @supported_se: NFC Secure Elements supported by the device 134 * @acknowledge_mode: Acknowledge mode used by the device 135 * @delay: delay between transactions in us 136 */ 137 struct nci_spi_dev *nci_spi_allocate_device(struct spi_device *spi, 138 struct nci_spi_ops *ops, 139 u32 supported_protocols, 140 u32 supported_se, 141 u8 acknowledge_mode, 142 unsigned int delay) 143 { 144 struct nci_spi_dev *ndev; 145 int tailroom = 0; 146 147 if (!ops->open || !ops->close || !ops->assert_int || !ops->deassert_int) 148 return NULL; 149 150 if (!supported_protocols) 151 return NULL; 152 153 ndev = devm_kzalloc(&spi->dev, sizeof(struct nci_dev), GFP_KERNEL); 154 if (!ndev) 155 return NULL; 156 157 ndev->ops = ops; 158 ndev->acknowledge_mode = acknowledge_mode; 159 ndev->xfer_udelay = delay; 160 161 if (acknowledge_mode == NCI_SPI_CRC_ENABLED) 162 tailroom += NCI_SPI_CRC_LEN; 163 164 ndev->nci_dev = nci_allocate_device(&nci_spi_ops, supported_protocols, 165 NCI_SPI_HDR_LEN, tailroom); 166 if (!ndev->nci_dev) 167 return NULL; 168 169 nci_set_drvdata(ndev->nci_dev, ndev); 170 171 return ndev; 172 } 173 EXPORT_SYMBOL_GPL(nci_spi_allocate_device); 174 175 /** 176 * nci_spi_free_device - deallocate nci spi device 177 * 178 * @ndev: The nci spi device to deallocate 179 */ 180 void nci_spi_free_device(struct nci_spi_dev *ndev) 181 { 182 nci_free_device(ndev->nci_dev); 183 } 184 EXPORT_SYMBOL_GPL(nci_spi_free_device); 185 186 /** 187 * nci_spi_register_device - register a nci spi device in the nfc subsystem 188 * 189 * @pdev: The nci spi device to register 190 */ 191 int nci_spi_register_device(struct nci_spi_dev *ndev) 192 { 193 return nci_register_device(ndev->nci_dev); 194 } 195 EXPORT_SYMBOL_GPL(nci_spi_register_device); 196 197 /** 198 * nci_spi_unregister_device - unregister a nci spi device in the nfc subsystem 199 * 200 * @dev: The nci spi device to unregister 201 */ 202 void nci_spi_unregister_device(struct nci_spi_dev *ndev) 203 { 204 nci_unregister_device(ndev->nci_dev); 205 } 206 EXPORT_SYMBOL_GPL(nci_spi_unregister_device); 207 208 static int send_acknowledge(struct nci_spi_dev *ndev, u8 acknowledge) 209 { 210 struct sk_buff *skb; 211 unsigned char *hdr; 212 u16 crc; 213 int ret; 214 215 skb = nci_skb_alloc(ndev->nci_dev, 0, GFP_KERNEL); 216 217 /* add the NCI SPI header to the start of the buffer */ 218 hdr = skb_push(skb, NCI_SPI_HDR_LEN); 219 hdr[0] = NCI_SPI_DIRECT_WRITE; 220 hdr[1] = NCI_SPI_CRC_ENABLED; 221 hdr[2] = acknowledge << NCI_SPI_ACK_SHIFT; 222 hdr[3] = 0; 223 224 crc = crc_ccitt(CRC_INIT, skb->data, skb->len); 225 *skb_put(skb, 1) = crc >> 8; 226 *skb_put(skb, 1) = crc & 0xFF; 227 228 ret = __nci_spi_send(ndev, skb); 229 230 kfree_skb(skb); 231 232 return ret; 233 } 234 235 static struct sk_buff *__nci_spi_recv_frame(struct nci_spi_dev *ndev) 236 { 237 struct sk_buff *skb; 238 struct spi_message m; 239 unsigned char req[2], resp_hdr[2]; 240 struct spi_transfer tx, rx; 241 unsigned short rx_len = 0; 242 int ret; 243 244 spi_message_init(&m); 245 req[0] = NCI_SPI_DIRECT_READ; 246 req[1] = ndev->acknowledge_mode; 247 tx.tx_buf = req; 248 tx.len = 2; 249 tx.cs_change = 0; 250 spi_message_add_tail(&tx, &m); 251 rx.rx_buf = resp_hdr; 252 rx.len = 2; 253 rx.cs_change = 1; 254 spi_message_add_tail(&rx, &m); 255 ret = spi_sync(ndev->spi, &m); 256 257 if (ret) 258 return NULL; 259 260 if (ndev->acknowledge_mode == NCI_SPI_CRC_ENABLED) 261 rx_len = ((resp_hdr[0] & NCI_SPI_MSB_PAYLOAD_MASK) << 8) + 262 resp_hdr[1] + NCI_SPI_CRC_LEN; 263 else 264 rx_len = (resp_hdr[0] << 8) | resp_hdr[1]; 265 266 skb = nci_skb_alloc(ndev->nci_dev, rx_len, GFP_KERNEL); 267 if (!skb) 268 return NULL; 269 270 spi_message_init(&m); 271 rx.rx_buf = skb_put(skb, rx_len); 272 rx.len = rx_len; 273 rx.cs_change = 0; 274 rx.delay_usecs = ndev->xfer_udelay; 275 spi_message_add_tail(&rx, &m); 276 ret = spi_sync(ndev->spi, &m); 277 278 if (ret) 279 goto receive_error; 280 281 if (ndev->acknowledge_mode == NCI_SPI_CRC_ENABLED) { 282 *skb_push(skb, 1) = resp_hdr[1]; 283 *skb_push(skb, 1) = resp_hdr[0]; 284 } 285 286 return skb; 287 288 receive_error: 289 kfree_skb(skb); 290 291 return NULL; 292 } 293 294 static int nci_spi_check_crc(struct sk_buff *skb) 295 { 296 u16 crc_data = (skb->data[skb->len - 2] << 8) | 297 skb->data[skb->len - 1]; 298 int ret; 299 300 ret = (crc_ccitt(CRC_INIT, skb->data, skb->len - NCI_SPI_CRC_LEN) 301 == crc_data); 302 303 skb_trim(skb, skb->len - NCI_SPI_CRC_LEN); 304 305 return ret; 306 } 307 308 static u8 nci_spi_get_ack(struct sk_buff *skb) 309 { 310 u8 ret; 311 312 ret = skb->data[0] >> NCI_SPI_ACK_SHIFT; 313 314 /* Remove NFCC part of the header: ACK, NACK and MSB payload len */ 315 skb_pull(skb, 2); 316 317 return ret; 318 } 319 320 /** 321 * nci_spi_recv_frame - receive frame from NCI SPI drivers 322 * 323 * @ndev: The nci spi device 324 * Context: can sleep 325 * 326 * This call may only be used from a context that may sleep. The sleep 327 * is non-interruptible, and has no timeout. 328 * 329 * It returns zero on success, else a negative error code. 330 */ 331 int nci_spi_recv_frame(struct nci_spi_dev *ndev) 332 { 333 struct sk_buff *skb; 334 int ret = 0; 335 336 ndev->ops->deassert_int(ndev); 337 338 /* Retrieve frame from SPI */ 339 skb = __nci_spi_recv_frame(ndev); 340 if (!skb) { 341 ret = -EIO; 342 goto done; 343 } 344 345 if (ndev->acknowledge_mode == NCI_SPI_CRC_ENABLED) { 346 if (!nci_spi_check_crc(skb)) { 347 send_acknowledge(ndev, ACKNOWLEDGE_NACK); 348 goto done; 349 } 350 351 /* In case of acknowledged mode: if ACK or NACK received, 352 * unblock completion of latest frame sent. 353 */ 354 ndev->req_result = nci_spi_get_ack(skb); 355 if (ndev->req_result) 356 complete(&ndev->req_completion); 357 } 358 359 /* If there is no payload (ACK/NACK only frame), 360 * free the socket buffer 361 */ 362 if (skb->len == 0) { 363 kfree_skb(skb); 364 goto done; 365 } 366 367 if (ndev->acknowledge_mode == NCI_SPI_CRC_ENABLED) 368 send_acknowledge(ndev, ACKNOWLEDGE_ACK); 369 370 /* Forward skb to NCI core layer */ 371 ret = nci_recv_frame(ndev->nci_dev, skb); 372 373 done: 374 ndev->ops->assert_int(ndev); 375 376 return ret; 377 } 378 EXPORT_SYMBOL_GPL(nci_spi_recv_frame); 379