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.value = nspi->xfer_udelay; 48 t.delay.unit = SPI_DELAY_UNIT_USECS; 49 t.speed_hz = nspi->xfer_speed_hz; 50 51 spi_message_init(&m); 52 spi_message_add_tail(&t, &m); 53 54 return spi_sync(nspi->spi, &m); 55 } 56 57 int nci_spi_send(struct nci_spi *nspi, 58 struct completion *write_handshake_completion, 59 struct sk_buff *skb) 60 { 61 unsigned int payload_len = skb->len; 62 unsigned char *hdr; 63 int ret; 64 long completion_rc; 65 66 /* add the NCI SPI header to the start of the buffer */ 67 hdr = skb_push(skb, NCI_SPI_HDR_LEN); 68 hdr[0] = NCI_SPI_DIRECT_WRITE; 69 hdr[1] = nspi->acknowledge_mode; 70 hdr[2] = payload_len >> 8; 71 hdr[3] = payload_len & 0xFF; 72 73 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) { 74 u16 crc; 75 76 crc = crc_ccitt(CRC_INIT, skb->data, skb->len); 77 skb_put_u8(skb, crc >> 8); 78 skb_put_u8(skb, crc & 0xFF); 79 } 80 81 if (write_handshake_completion) { 82 /* Trick SPI driver to raise chip select */ 83 ret = __nci_spi_send(nspi, NULL, 1); 84 if (ret) 85 goto done; 86 87 /* wait for NFC chip hardware handshake to complete */ 88 if (wait_for_completion_timeout(write_handshake_completion, 89 msecs_to_jiffies(1000)) == 0) { 90 ret = -ETIME; 91 goto done; 92 } 93 } 94 95 ret = __nci_spi_send(nspi, skb, 0); 96 if (ret != 0 || nspi->acknowledge_mode == NCI_SPI_CRC_DISABLED) 97 goto done; 98 99 reinit_completion(&nspi->req_completion); 100 completion_rc = wait_for_completion_interruptible_timeout( 101 &nspi->req_completion, 102 NCI_SPI_SEND_TIMEOUT); 103 104 if (completion_rc <= 0 || nspi->req_result == ACKNOWLEDGE_NACK) 105 ret = -EIO; 106 107 done: 108 kfree_skb(skb); 109 110 return ret; 111 } 112 EXPORT_SYMBOL_GPL(nci_spi_send); 113 114 /* ---- Interface to NCI SPI drivers ---- */ 115 116 /** 117 * nci_spi_allocate_spi - allocate a new nci spi 118 * 119 * @spi: SPI device 120 * @acknowledge_mode: Acknowledge mode used by the NFC device 121 * @delay: delay between transactions in us 122 * @ndev: nci dev to send incoming nci frames to 123 */ 124 struct nci_spi *nci_spi_allocate_spi(struct spi_device *spi, 125 u8 acknowledge_mode, unsigned int delay, 126 struct nci_dev *ndev) 127 { 128 struct nci_spi *nspi; 129 130 nspi = devm_kzalloc(&spi->dev, sizeof(struct nci_spi), GFP_KERNEL); 131 if (!nspi) 132 return NULL; 133 134 nspi->acknowledge_mode = acknowledge_mode; 135 nspi->xfer_udelay = delay; 136 /* Use controller max SPI speed by default */ 137 nspi->xfer_speed_hz = 0; 138 nspi->spi = spi; 139 nspi->ndev = ndev; 140 init_completion(&nspi->req_completion); 141 142 return nspi; 143 } 144 EXPORT_SYMBOL_GPL(nci_spi_allocate_spi); 145 146 static int send_acknowledge(struct nci_spi *nspi, u8 acknowledge) 147 { 148 struct sk_buff *skb; 149 unsigned char *hdr; 150 u16 crc; 151 int ret; 152 153 skb = nci_skb_alloc(nspi->ndev, 0, GFP_KERNEL); 154 155 /* add the NCI SPI header to the start of the buffer */ 156 hdr = skb_push(skb, NCI_SPI_HDR_LEN); 157 hdr[0] = NCI_SPI_DIRECT_WRITE; 158 hdr[1] = NCI_SPI_CRC_ENABLED; 159 hdr[2] = acknowledge << NCI_SPI_ACK_SHIFT; 160 hdr[3] = 0; 161 162 crc = crc_ccitt(CRC_INIT, skb->data, skb->len); 163 skb_put_u8(skb, crc >> 8); 164 skb_put_u8(skb, crc & 0xFF); 165 166 ret = __nci_spi_send(nspi, skb, 0); 167 168 kfree_skb(skb); 169 170 return ret; 171 } 172 173 static struct sk_buff *__nci_spi_read(struct nci_spi *nspi) 174 { 175 struct sk_buff *skb; 176 struct spi_message m; 177 unsigned char req[2], resp_hdr[2]; 178 struct spi_transfer tx, rx; 179 unsigned short rx_len = 0; 180 int ret; 181 182 spi_message_init(&m); 183 184 memset(&tx, 0, sizeof(struct spi_transfer)); 185 req[0] = NCI_SPI_DIRECT_READ; 186 req[1] = nspi->acknowledge_mode; 187 tx.tx_buf = req; 188 tx.len = 2; 189 tx.cs_change = 0; 190 tx.speed_hz = nspi->xfer_speed_hz; 191 spi_message_add_tail(&tx, &m); 192 193 memset(&rx, 0, sizeof(struct spi_transfer)); 194 rx.rx_buf = resp_hdr; 195 rx.len = 2; 196 rx.cs_change = 1; 197 rx.speed_hz = nspi->xfer_speed_hz; 198 spi_message_add_tail(&rx, &m); 199 200 ret = spi_sync(nspi->spi, &m); 201 if (ret) 202 return NULL; 203 204 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) 205 rx_len = ((resp_hdr[0] & NCI_SPI_MSB_PAYLOAD_MASK) << 8) + 206 resp_hdr[1] + NCI_SPI_CRC_LEN; 207 else 208 rx_len = (resp_hdr[0] << 8) | resp_hdr[1]; 209 210 skb = nci_skb_alloc(nspi->ndev, rx_len, GFP_KERNEL); 211 if (!skb) 212 return NULL; 213 214 spi_message_init(&m); 215 216 memset(&rx, 0, sizeof(struct spi_transfer)); 217 rx.rx_buf = skb_put(skb, rx_len); 218 rx.len = rx_len; 219 rx.cs_change = 0; 220 rx.delay.value = nspi->xfer_udelay; 221 rx.delay.unit = SPI_DELAY_UNIT_USECS; 222 rx.speed_hz = nspi->xfer_speed_hz; 223 spi_message_add_tail(&rx, &m); 224 225 ret = spi_sync(nspi->spi, &m); 226 if (ret) 227 goto receive_error; 228 229 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) { 230 *(u8 *)skb_push(skb, 1) = resp_hdr[1]; 231 *(u8 *)skb_push(skb, 1) = resp_hdr[0]; 232 } 233 234 return skb; 235 236 receive_error: 237 kfree_skb(skb); 238 239 return NULL; 240 } 241 242 static int nci_spi_check_crc(struct sk_buff *skb) 243 { 244 u16 crc_data = (skb->data[skb->len - 2] << 8) | 245 skb->data[skb->len - 1]; 246 int ret; 247 248 ret = (crc_ccitt(CRC_INIT, skb->data, skb->len - NCI_SPI_CRC_LEN) 249 == crc_data); 250 251 skb_trim(skb, skb->len - NCI_SPI_CRC_LEN); 252 253 return ret; 254 } 255 256 static u8 nci_spi_get_ack(struct sk_buff *skb) 257 { 258 u8 ret; 259 260 ret = skb->data[0] >> NCI_SPI_ACK_SHIFT; 261 262 /* Remove NFCC part of the header: ACK, NACK and MSB payload len */ 263 skb_pull(skb, 2); 264 265 return ret; 266 } 267 268 /** 269 * nci_spi_read - read frame from NCI SPI drivers 270 * 271 * @nspi: The nci spi 272 * Context: can sleep 273 * 274 * This call may only be used from a context that may sleep. The sleep 275 * is non-interruptible, and has no timeout. 276 * 277 * It returns an allocated skb containing the frame on success, or NULL. 278 */ 279 struct sk_buff *nci_spi_read(struct nci_spi *nspi) 280 { 281 struct sk_buff *skb; 282 283 /* Retrieve frame from SPI */ 284 skb = __nci_spi_read(nspi); 285 if (!skb) 286 goto done; 287 288 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) { 289 if (!nci_spi_check_crc(skb)) { 290 send_acknowledge(nspi, ACKNOWLEDGE_NACK); 291 goto done; 292 } 293 294 /* In case of acknowledged mode: if ACK or NACK received, 295 * unblock completion of latest frame sent. 296 */ 297 nspi->req_result = nci_spi_get_ack(skb); 298 if (nspi->req_result) 299 complete(&nspi->req_completion); 300 } 301 302 /* If there is no payload (ACK/NACK only frame), 303 * free the socket buffer 304 */ 305 if (!skb->len) { 306 kfree_skb(skb); 307 skb = NULL; 308 goto done; 309 } 310 311 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) 312 send_acknowledge(nspi, ACKNOWLEDGE_ACK); 313 314 done: 315 316 return skb; 317 } 318 EXPORT_SYMBOL_GPL(nci_spi_read); 319 320 MODULE_LICENSE("GPL"); 321