1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2013 Intel Corporation. All rights reserved. 4 */ 5 6 #define pr_fmt(fmt) "nci_spi: %s: " fmt, __func__ 7 8 #include <linux/module.h> 9 10 #include <linux/export.h> 11 #include <linux/spi/spi.h> 12 #include <linux/crc-ccitt.h> 13 #include <net/nfc/nci_core.h> 14 15 #define NCI_SPI_ACK_SHIFT 6 16 #define NCI_SPI_MSB_PAYLOAD_MASK 0x3F 17 18 #define NCI_SPI_SEND_TIMEOUT (NCI_CMD_TIMEOUT > NCI_DATA_TIMEOUT ? \ 19 NCI_CMD_TIMEOUT : NCI_DATA_TIMEOUT) 20 21 #define NCI_SPI_DIRECT_WRITE 0x01 22 #define NCI_SPI_DIRECT_READ 0x02 23 24 #define ACKNOWLEDGE_NONE 0 25 #define ACKNOWLEDGE_ACK 1 26 #define ACKNOWLEDGE_NACK 2 27 28 #define CRC_INIT 0xFFFF 29 30 static int __nci_spi_send(struct nci_spi *nspi, struct sk_buff *skb, 31 int cs_change) 32 { 33 struct spi_message m; 34 struct spi_transfer t; 35 36 memset(&t, 0, sizeof(struct spi_transfer)); 37 /* a NULL skb means we just want the SPI chip select line to raise */ 38 if (skb) { 39 t.tx_buf = skb->data; 40 t.len = skb->len; 41 } else { 42 /* still set tx_buf non NULL to make the driver happy */ 43 t.tx_buf = &t; 44 t.len = 0; 45 } 46 t.cs_change = cs_change; 47 t.delay_usecs = nspi->xfer_udelay; 48 t.speed_hz = nspi->xfer_speed_hz; 49 50 spi_message_init(&m); 51 spi_message_add_tail(&t, &m); 52 53 return spi_sync(nspi->spi, &m); 54 } 55 56 int nci_spi_send(struct nci_spi *nspi, 57 struct completion *write_handshake_completion, 58 struct sk_buff *skb) 59 { 60 unsigned int payload_len = skb->len; 61 unsigned char *hdr; 62 int ret; 63 long completion_rc; 64 65 /* add the NCI SPI header to the start of the buffer */ 66 hdr = skb_push(skb, NCI_SPI_HDR_LEN); 67 hdr[0] = NCI_SPI_DIRECT_WRITE; 68 hdr[1] = nspi->acknowledge_mode; 69 hdr[2] = payload_len >> 8; 70 hdr[3] = payload_len & 0xFF; 71 72 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) { 73 u16 crc; 74 75 crc = crc_ccitt(CRC_INIT, skb->data, skb->len); 76 skb_put_u8(skb, crc >> 8); 77 skb_put_u8(skb, crc & 0xFF); 78 } 79 80 if (write_handshake_completion) { 81 /* Trick SPI driver to raise chip select */ 82 ret = __nci_spi_send(nspi, NULL, 1); 83 if (ret) 84 goto done; 85 86 /* wait for NFC chip hardware handshake to complete */ 87 if (wait_for_completion_timeout(write_handshake_completion, 88 msecs_to_jiffies(1000)) == 0) { 89 ret = -ETIME; 90 goto done; 91 } 92 } 93 94 ret = __nci_spi_send(nspi, skb, 0); 95 if (ret != 0 || nspi->acknowledge_mode == NCI_SPI_CRC_DISABLED) 96 goto done; 97 98 reinit_completion(&nspi->req_completion); 99 completion_rc = wait_for_completion_interruptible_timeout( 100 &nspi->req_completion, 101 NCI_SPI_SEND_TIMEOUT); 102 103 if (completion_rc <= 0 || nspi->req_result == ACKNOWLEDGE_NACK) 104 ret = -EIO; 105 106 done: 107 kfree_skb(skb); 108 109 return ret; 110 } 111 EXPORT_SYMBOL_GPL(nci_spi_send); 112 113 /* ---- Interface to NCI SPI drivers ---- */ 114 115 /** 116 * nci_spi_allocate_spi - allocate a new nci spi 117 * 118 * @spi: SPI device 119 * @acknowledge_mode: Acknowledge mode used by the NFC device 120 * @delay: delay between transactions in us 121 * @ndev: nci dev to send incoming nci frames to 122 */ 123 struct nci_spi *nci_spi_allocate_spi(struct spi_device *spi, 124 u8 acknowledge_mode, unsigned int delay, 125 struct nci_dev *ndev) 126 { 127 struct nci_spi *nspi; 128 129 nspi = devm_kzalloc(&spi->dev, sizeof(struct nci_spi), GFP_KERNEL); 130 if (!nspi) 131 return NULL; 132 133 nspi->acknowledge_mode = acknowledge_mode; 134 nspi->xfer_udelay = delay; 135 /* Use controller max SPI speed by default */ 136 nspi->xfer_speed_hz = 0; 137 nspi->spi = spi; 138 nspi->ndev = ndev; 139 init_completion(&nspi->req_completion); 140 141 return nspi; 142 } 143 EXPORT_SYMBOL_GPL(nci_spi_allocate_spi); 144 145 static int send_acknowledge(struct nci_spi *nspi, u8 acknowledge) 146 { 147 struct sk_buff *skb; 148 unsigned char *hdr; 149 u16 crc; 150 int ret; 151 152 skb = nci_skb_alloc(nspi->ndev, 0, GFP_KERNEL); 153 154 /* add the NCI SPI header to the start of the buffer */ 155 hdr = skb_push(skb, NCI_SPI_HDR_LEN); 156 hdr[0] = NCI_SPI_DIRECT_WRITE; 157 hdr[1] = NCI_SPI_CRC_ENABLED; 158 hdr[2] = acknowledge << NCI_SPI_ACK_SHIFT; 159 hdr[3] = 0; 160 161 crc = crc_ccitt(CRC_INIT, skb->data, skb->len); 162 skb_put_u8(skb, crc >> 8); 163 skb_put_u8(skb, crc & 0xFF); 164 165 ret = __nci_spi_send(nspi, skb, 0); 166 167 kfree_skb(skb); 168 169 return ret; 170 } 171 172 static struct sk_buff *__nci_spi_read(struct nci_spi *nspi) 173 { 174 struct sk_buff *skb; 175 struct spi_message m; 176 unsigned char req[2], resp_hdr[2]; 177 struct spi_transfer tx, rx; 178 unsigned short rx_len = 0; 179 int ret; 180 181 spi_message_init(&m); 182 183 memset(&tx, 0, sizeof(struct spi_transfer)); 184 req[0] = NCI_SPI_DIRECT_READ; 185 req[1] = nspi->acknowledge_mode; 186 tx.tx_buf = req; 187 tx.len = 2; 188 tx.cs_change = 0; 189 tx.speed_hz = nspi->xfer_speed_hz; 190 spi_message_add_tail(&tx, &m); 191 192 memset(&rx, 0, sizeof(struct spi_transfer)); 193 rx.rx_buf = resp_hdr; 194 rx.len = 2; 195 rx.cs_change = 1; 196 rx.speed_hz = nspi->xfer_speed_hz; 197 spi_message_add_tail(&rx, &m); 198 199 ret = spi_sync(nspi->spi, &m); 200 if (ret) 201 return NULL; 202 203 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) 204 rx_len = ((resp_hdr[0] & NCI_SPI_MSB_PAYLOAD_MASK) << 8) + 205 resp_hdr[1] + NCI_SPI_CRC_LEN; 206 else 207 rx_len = (resp_hdr[0] << 8) | resp_hdr[1]; 208 209 skb = nci_skb_alloc(nspi->ndev, rx_len, GFP_KERNEL); 210 if (!skb) 211 return NULL; 212 213 spi_message_init(&m); 214 215 memset(&rx, 0, sizeof(struct spi_transfer)); 216 rx.rx_buf = skb_put(skb, rx_len); 217 rx.len = rx_len; 218 rx.cs_change = 0; 219 rx.delay_usecs = nspi->xfer_udelay; 220 rx.speed_hz = nspi->xfer_speed_hz; 221 spi_message_add_tail(&rx, &m); 222 223 ret = spi_sync(nspi->spi, &m); 224 if (ret) 225 goto receive_error; 226 227 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) { 228 *(u8 *)skb_push(skb, 1) = resp_hdr[1]; 229 *(u8 *)skb_push(skb, 1) = resp_hdr[0]; 230 } 231 232 return skb; 233 234 receive_error: 235 kfree_skb(skb); 236 237 return NULL; 238 } 239 240 static int nci_spi_check_crc(struct sk_buff *skb) 241 { 242 u16 crc_data = (skb->data[skb->len - 2] << 8) | 243 skb->data[skb->len - 1]; 244 int ret; 245 246 ret = (crc_ccitt(CRC_INIT, skb->data, skb->len - NCI_SPI_CRC_LEN) 247 == crc_data); 248 249 skb_trim(skb, skb->len - NCI_SPI_CRC_LEN); 250 251 return ret; 252 } 253 254 static u8 nci_spi_get_ack(struct sk_buff *skb) 255 { 256 u8 ret; 257 258 ret = skb->data[0] >> NCI_SPI_ACK_SHIFT; 259 260 /* Remove NFCC part of the header: ACK, NACK and MSB payload len */ 261 skb_pull(skb, 2); 262 263 return ret; 264 } 265 266 /** 267 * nci_spi_read - read frame from NCI SPI drivers 268 * 269 * @nspi: The nci spi 270 * Context: can sleep 271 * 272 * This call may only be used from a context that may sleep. The sleep 273 * is non-interruptible, and has no timeout. 274 * 275 * It returns an allocated skb containing the frame on success, or NULL. 276 */ 277 struct sk_buff *nci_spi_read(struct nci_spi *nspi) 278 { 279 struct sk_buff *skb; 280 281 /* Retrieve frame from SPI */ 282 skb = __nci_spi_read(nspi); 283 if (!skb) 284 goto done; 285 286 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) { 287 if (!nci_spi_check_crc(skb)) { 288 send_acknowledge(nspi, ACKNOWLEDGE_NACK); 289 goto done; 290 } 291 292 /* In case of acknowledged mode: if ACK or NACK received, 293 * unblock completion of latest frame sent. 294 */ 295 nspi->req_result = nci_spi_get_ack(skb); 296 if (nspi->req_result) 297 complete(&nspi->req_completion); 298 } 299 300 /* If there is no payload (ACK/NACK only frame), 301 * free the socket buffer 302 */ 303 if (!skb->len) { 304 kfree_skb(skb); 305 skb = NULL; 306 goto done; 307 } 308 309 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) 310 send_acknowledge(nspi, ACKNOWLEDGE_ACK); 311 312 done: 313 314 return skb; 315 } 316 EXPORT_SYMBOL_GPL(nci_spi_read); 317 318 MODULE_LICENSE("GPL"); 319