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, const 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 if (!skb) 155 return -ENOMEM; 156 157 /* add the NCI SPI header to the start of the buffer */ 158 hdr = skb_push(skb, NCI_SPI_HDR_LEN); 159 hdr[0] = NCI_SPI_DIRECT_WRITE; 160 hdr[1] = NCI_SPI_CRC_ENABLED; 161 hdr[2] = acknowledge << NCI_SPI_ACK_SHIFT; 162 hdr[3] = 0; 163 164 crc = crc_ccitt(CRC_INIT, skb->data, skb->len); 165 skb_put_u8(skb, crc >> 8); 166 skb_put_u8(skb, crc & 0xFF); 167 168 ret = __nci_spi_send(nspi, skb, 0); 169 170 kfree_skb(skb); 171 172 return ret; 173 } 174 175 static struct sk_buff *__nci_spi_read(struct nci_spi *nspi) 176 { 177 struct sk_buff *skb; 178 struct spi_message m; 179 unsigned char req[2], resp_hdr[2]; 180 struct spi_transfer tx, rx; 181 unsigned short rx_len = 0; 182 int ret; 183 184 spi_message_init(&m); 185 186 memset(&tx, 0, sizeof(struct spi_transfer)); 187 req[0] = NCI_SPI_DIRECT_READ; 188 req[1] = nspi->acknowledge_mode; 189 tx.tx_buf = req; 190 tx.len = 2; 191 tx.cs_change = 0; 192 tx.speed_hz = nspi->xfer_speed_hz; 193 spi_message_add_tail(&tx, &m); 194 195 memset(&rx, 0, sizeof(struct spi_transfer)); 196 rx.rx_buf = resp_hdr; 197 rx.len = 2; 198 rx.cs_change = 1; 199 rx.speed_hz = nspi->xfer_speed_hz; 200 spi_message_add_tail(&rx, &m); 201 202 ret = spi_sync(nspi->spi, &m); 203 if (ret) 204 return NULL; 205 206 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) 207 rx_len = ((resp_hdr[0] & NCI_SPI_MSB_PAYLOAD_MASK) << 8) + 208 resp_hdr[1] + NCI_SPI_CRC_LEN; 209 else 210 rx_len = (resp_hdr[0] << 8) | resp_hdr[1]; 211 212 skb = nci_skb_alloc(nspi->ndev, rx_len, GFP_KERNEL); 213 if (!skb) 214 return NULL; 215 216 spi_message_init(&m); 217 218 memset(&rx, 0, sizeof(struct spi_transfer)); 219 rx.rx_buf = skb_put(skb, rx_len); 220 rx.len = rx_len; 221 rx.cs_change = 0; 222 rx.delay.value = nspi->xfer_udelay; 223 rx.delay.unit = SPI_DELAY_UNIT_USECS; 224 rx.speed_hz = nspi->xfer_speed_hz; 225 spi_message_add_tail(&rx, &m); 226 227 ret = spi_sync(nspi->spi, &m); 228 if (ret) 229 goto receive_error; 230 231 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) { 232 *(u8 *)skb_push(skb, 1) = resp_hdr[1]; 233 *(u8 *)skb_push(skb, 1) = resp_hdr[0]; 234 } 235 236 return skb; 237 238 receive_error: 239 kfree_skb(skb); 240 241 return NULL; 242 } 243 244 static int nci_spi_check_crc(struct sk_buff *skb) 245 { 246 u16 crc_data = (skb->data[skb->len - 2] << 8) | 247 skb->data[skb->len - 1]; 248 int ret; 249 250 ret = (crc_ccitt(CRC_INIT, skb->data, skb->len - NCI_SPI_CRC_LEN) 251 == crc_data); 252 253 skb_trim(skb, skb->len - NCI_SPI_CRC_LEN); 254 255 return ret; 256 } 257 258 static u8 nci_spi_get_ack(struct sk_buff *skb) 259 { 260 u8 ret; 261 262 ret = skb->data[0] >> NCI_SPI_ACK_SHIFT; 263 264 /* Remove NFCC part of the header: ACK, NACK and MSB payload len */ 265 skb_pull(skb, 2); 266 267 return ret; 268 } 269 270 /** 271 * nci_spi_read - read frame from NCI SPI drivers 272 * 273 * @nspi: The nci spi 274 * Context: can sleep 275 * 276 * This call may only be used from a context that may sleep. The sleep 277 * is non-interruptible, and has no timeout. 278 * 279 * It returns an allocated skb containing the frame on success, or NULL. 280 */ 281 struct sk_buff *nci_spi_read(struct nci_spi *nspi) 282 { 283 struct sk_buff *skb; 284 285 /* Retrieve frame from SPI */ 286 skb = __nci_spi_read(nspi); 287 if (!skb) 288 goto done; 289 290 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) { 291 if (!nci_spi_check_crc(skb)) { 292 send_acknowledge(nspi, ACKNOWLEDGE_NACK); 293 goto done; 294 } 295 296 /* In case of acknowledged mode: if ACK or NACK received, 297 * unblock completion of latest frame sent. 298 */ 299 nspi->req_result = nci_spi_get_ack(skb); 300 if (nspi->req_result) 301 complete(&nspi->req_completion); 302 } 303 304 /* If there is no payload (ACK/NACK only frame), 305 * free the socket buffer 306 */ 307 if (!skb->len) { 308 kfree_skb(skb); 309 skb = NULL; 310 goto done; 311 } 312 313 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) 314 send_acknowledge(nspi, ACKNOWLEDGE_ACK); 315 316 done: 317 318 return skb; 319 } 320 EXPORT_SYMBOL_GPL(nci_spi_read); 321 322 MODULE_DESCRIPTION("NFC Controller Interface (NCI) SPI link layer"); 323 MODULE_LICENSE("GPL"); 324