2 * Copyright (C) 2013 Intel Corporation. All rights reserved.
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.
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
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.
19 #define pr_fmt(fmt) "nci_spi: %s: " fmt, __func__
21 #include <linux/module.h>
23 #include <linux/export.h>
24 #include <linux/spi/spi.h>
25 #include <linux/crc-ccitt.h>
26 #include <net/nfc/nci_core.h>
28 #define NCI_SPI_ACK_SHIFT 6
29 #define NCI_SPI_MSB_PAYLOAD_MASK 0x3F
31 #define NCI_SPI_SEND_TIMEOUT (NCI_CMD_TIMEOUT > NCI_DATA_TIMEOUT ? \
32 NCI_CMD_TIMEOUT : NCI_DATA_TIMEOUT)
34 #define NCI_SPI_DIRECT_WRITE 0x01
35 #define NCI_SPI_DIRECT_READ 0x02
37 #define ACKNOWLEDGE_NONE 0
38 #define ACKNOWLEDGE_ACK 1
39 #define ACKNOWLEDGE_NACK 2
41 #define CRC_INIT 0xFFFF
43 static int __nci_spi_send(struct nci_spi *nspi, struct sk_buff *skb,
47 struct spi_transfer t;
49 memset(&t, 0, sizeof(struct spi_transfer));
50 /* a NULL skb means we just want the SPI chip select line to raise */
55 /* still set tx_buf non NULL to make the driver happy */
59 t.cs_change = cs_change;
60 t.delay_usecs = nspi->xfer_udelay;
61 t.speed_hz = nspi->xfer_speed_hz;
64 spi_message_add_tail(&t, &m);
66 return spi_sync(nspi->spi, &m);
69 int nci_spi_send(struct nci_spi *nspi,
70 struct completion *write_handshake_completion,
73 unsigned int payload_len = skb->len;
78 /* add the NCI SPI header to the start of the buffer */
79 hdr = skb_push(skb, NCI_SPI_HDR_LEN);
80 hdr[0] = NCI_SPI_DIRECT_WRITE;
81 hdr[1] = nspi->acknowledge_mode;
82 hdr[2] = payload_len >> 8;
83 hdr[3] = payload_len & 0xFF;
85 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
88 crc = crc_ccitt(CRC_INIT, skb->data, skb->len);
89 *skb_put(skb, 1) = crc >> 8;
90 *skb_put(skb, 1) = crc & 0xFF;
93 if (write_handshake_completion) {
94 /* Trick SPI driver to raise chip select */
95 ret = __nci_spi_send(nspi, NULL, 1);
99 /* wait for NFC chip hardware handshake to complete */
100 if (wait_for_completion_timeout(write_handshake_completion,
101 msecs_to_jiffies(1000)) == 0) {
107 ret = __nci_spi_send(nspi, skb, 0);
108 if (ret != 0 || nspi->acknowledge_mode == NCI_SPI_CRC_DISABLED)
111 reinit_completion(&nspi->req_completion);
112 completion_rc = wait_for_completion_interruptible_timeout(
113 &nspi->req_completion,
114 NCI_SPI_SEND_TIMEOUT);
116 if (completion_rc <= 0 || nspi->req_result == ACKNOWLEDGE_NACK)
124 EXPORT_SYMBOL_GPL(nci_spi_send);
126 /* ---- Interface to NCI SPI drivers ---- */
129 * nci_spi_allocate_spi - allocate a new nci spi
132 * @acknowledge_mode: Acknowledge mode used by the NFC device
133 * @delay: delay between transactions in us
134 * @ndev: nci dev to send incoming nci frames to
136 struct nci_spi *nci_spi_allocate_spi(struct spi_device *spi,
137 u8 acknowledge_mode, unsigned int delay,
138 struct nci_dev *ndev)
140 struct nci_spi *nspi;
142 nspi = devm_kzalloc(&spi->dev, sizeof(struct nci_spi), GFP_KERNEL);
146 nspi->acknowledge_mode = acknowledge_mode;
147 nspi->xfer_udelay = delay;
148 /* Use controller max SPI speed by default */
149 nspi->xfer_speed_hz = 0;
152 init_completion(&nspi->req_completion);
156 EXPORT_SYMBOL_GPL(nci_spi_allocate_spi);
158 static int send_acknowledge(struct nci_spi *nspi, u8 acknowledge)
165 skb = nci_skb_alloc(nspi->ndev, 0, GFP_KERNEL);
167 /* add the NCI SPI header to the start of the buffer */
168 hdr = skb_push(skb, NCI_SPI_HDR_LEN);
169 hdr[0] = NCI_SPI_DIRECT_WRITE;
170 hdr[1] = NCI_SPI_CRC_ENABLED;
171 hdr[2] = acknowledge << NCI_SPI_ACK_SHIFT;
174 crc = crc_ccitt(CRC_INIT, skb->data, skb->len);
175 *skb_put(skb, 1) = crc >> 8;
176 *skb_put(skb, 1) = crc & 0xFF;
178 ret = __nci_spi_send(nspi, skb, 0);
185 static struct sk_buff *__nci_spi_read(struct nci_spi *nspi)
188 struct spi_message m;
189 unsigned char req[2], resp_hdr[2];
190 struct spi_transfer tx, rx;
191 unsigned short rx_len = 0;
194 spi_message_init(&m);
196 memset(&tx, 0, sizeof(struct spi_transfer));
197 req[0] = NCI_SPI_DIRECT_READ;
198 req[1] = nspi->acknowledge_mode;
202 tx.speed_hz = nspi->xfer_speed_hz;
203 spi_message_add_tail(&tx, &m);
205 memset(&rx, 0, sizeof(struct spi_transfer));
206 rx.rx_buf = resp_hdr;
209 rx.speed_hz = nspi->xfer_speed_hz;
210 spi_message_add_tail(&rx, &m);
212 ret = spi_sync(nspi->spi, &m);
216 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED)
217 rx_len = ((resp_hdr[0] & NCI_SPI_MSB_PAYLOAD_MASK) << 8) +
218 resp_hdr[1] + NCI_SPI_CRC_LEN;
220 rx_len = (resp_hdr[0] << 8) | resp_hdr[1];
222 skb = nci_skb_alloc(nspi->ndev, rx_len, GFP_KERNEL);
226 spi_message_init(&m);
228 memset(&rx, 0, sizeof(struct spi_transfer));
229 rx.rx_buf = skb_put(skb, rx_len);
232 rx.delay_usecs = nspi->xfer_udelay;
233 rx.speed_hz = nspi->xfer_speed_hz;
234 spi_message_add_tail(&rx, &m);
236 ret = spi_sync(nspi->spi, &m);
240 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
241 *skb_push(skb, 1) = resp_hdr[1];
242 *skb_push(skb, 1) = resp_hdr[0];
253 static int nci_spi_check_crc(struct sk_buff *skb)
255 u16 crc_data = (skb->data[skb->len - 2] << 8) |
256 skb->data[skb->len - 1];
259 ret = (crc_ccitt(CRC_INIT, skb->data, skb->len - NCI_SPI_CRC_LEN)
262 skb_trim(skb, skb->len - NCI_SPI_CRC_LEN);
267 static u8 nci_spi_get_ack(struct sk_buff *skb)
271 ret = skb->data[0] >> NCI_SPI_ACK_SHIFT;
273 /* Remove NFCC part of the header: ACK, NACK and MSB payload len */
280 * nci_spi_read - read frame from NCI SPI drivers
285 * This call may only be used from a context that may sleep. The sleep
286 * is non-interruptible, and has no timeout.
288 * It returns an allocated skb containing the frame on success, or NULL.
290 struct sk_buff *nci_spi_read(struct nci_spi *nspi)
294 /* Retrieve frame from SPI */
295 skb = __nci_spi_read(nspi);
299 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
300 if (!nci_spi_check_crc(skb)) {
301 send_acknowledge(nspi, ACKNOWLEDGE_NACK);
305 /* In case of acknowledged mode: if ACK or NACK received,
306 * unblock completion of latest frame sent.
308 nspi->req_result = nci_spi_get_ack(skb);
309 if (nspi->req_result)
310 complete(&nspi->req_completion);
313 /* If there is no payload (ACK/NACK only frame),
314 * free the socket buffer
322 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED)
323 send_acknowledge(nspi, ACKNOWLEDGE_ACK);
329 EXPORT_SYMBOL_GPL(nci_spi_read);
331 MODULE_LICENSE("GPL");