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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/module.h>
22
23#include <linux/export.h>
24#include <linux/spi/spi.h>
25#include <linux/crc-ccitt.h>
26#include <net/nfc/nci_core.h>
27
28#define NCI_SPI_ACK_SHIFT 6
29#define NCI_SPI_MSB_PAYLOAD_MASK 0x3F
30
31#define NCI_SPI_SEND_TIMEOUT (NCI_CMD_TIMEOUT > NCI_DATA_TIMEOUT ? \
32 NCI_CMD_TIMEOUT : NCI_DATA_TIMEOUT)
33
34#define NCI_SPI_DIRECT_WRITE 0x01
35#define NCI_SPI_DIRECT_READ 0x02
36
37#define ACKNOWLEDGE_NONE 0
38#define ACKNOWLEDGE_ACK 1
39#define ACKNOWLEDGE_NACK 2
40
41#define CRC_INIT 0xFFFF
42
43static int __nci_spi_send(struct nci_spi *nspi, struct sk_buff *skb,
44 int cs_change)
45{
46 struct spi_message m;
47 struct spi_transfer t;
48
49 memset(&t, 0, sizeof(struct spi_transfer));
50 /* a NULL skb means we just want the SPI chip select line to raise */
51 if (skb) {
52 t.tx_buf = skb->data;
53 t.len = skb->len;
54 } else {
55 /* still set tx_buf non NULL to make the driver happy */
56 t.tx_buf = &t;
57 t.len = 0;
58 }
59 t.cs_change = cs_change;
60 t.delay_usecs = nspi->xfer_udelay;
61 t.speed_hz = nspi->xfer_speed_hz;
62
63 spi_message_init(&m);
64 spi_message_add_tail(&t, &m);
65
66 return spi_sync(nspi->spi, &m);
67}
68
69int nci_spi_send(struct nci_spi *nspi,
70 struct completion *write_handshake_completion,
71 struct sk_buff *skb)
72{
73 unsigned int payload_len = skb->len;
74 unsigned char *hdr;
75 int ret;
76 long completion_rc;
77
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;
84
85 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
86 u16 crc;
87
88 crc = crc_ccitt(CRC_INIT, skb->data, skb->len);
89 *skb_put(skb, 1) = crc >> 8;
90 *skb_put(skb, 1) = crc & 0xFF;
91 }
92
93 if (write_handshake_completion) {
94 /* Trick SPI driver to raise chip select */
95 ret = __nci_spi_send(nspi, NULL, 1);
96 if (ret)
97 goto done;
98
99 /* wait for NFC chip hardware handshake to complete */
100 if (wait_for_completion_timeout(write_handshake_completion,
101 msecs_to_jiffies(1000)) == 0) {
102 ret = -ETIME;
103 goto done;
104 }
105 }
106
107 ret = __nci_spi_send(nspi, skb, 0);
108 if (ret != 0 || nspi->acknowledge_mode == NCI_SPI_CRC_DISABLED)
109 goto done;
110
111 reinit_completion(&nspi->req_completion);
112 completion_rc = wait_for_completion_interruptible_timeout(
113 &nspi->req_completion,
114 NCI_SPI_SEND_TIMEOUT);
115
116 if (completion_rc <= 0 || nspi->req_result == ACKNOWLEDGE_NACK)
117 ret = -EIO;
118
119done:
120 kfree_skb(skb);
121
122 return ret;
123}
124EXPORT_SYMBOL_GPL(nci_spi_send);
125
126/* ---- Interface to NCI SPI drivers ---- */
127
128/**
129 * nci_spi_allocate_spi - allocate a new nci spi
130 *
131 * @spi: SPI device
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
135 */
136struct nci_spi *nci_spi_allocate_spi(struct spi_device *spi,
137 u8 acknowledge_mode, unsigned int delay,
138 struct nci_dev *ndev)
139{
140 struct nci_spi *nspi;
141
142 nspi = devm_kzalloc(&spi->dev, sizeof(struct nci_spi), GFP_KERNEL);
143 if (!nspi)
144 return NULL;
145
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;
150 nspi->spi = spi;
151 nspi->ndev = ndev;
152 init_completion(&nspi->req_completion);
153
154 return nspi;
155}
156EXPORT_SYMBOL_GPL(nci_spi_allocate_spi);
157
158static int send_acknowledge(struct nci_spi *nspi, u8 acknowledge)
159{
160 struct sk_buff *skb;
161 unsigned char *hdr;
162 u16 crc;
163 int ret;
164
165 skb = nci_skb_alloc(nspi->ndev, 0, GFP_KERNEL);
166
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;
172 hdr[3] = 0;
173
174 crc = crc_ccitt(CRC_INIT, skb->data, skb->len);
175 *skb_put(skb, 1) = crc >> 8;
176 *skb_put(skb, 1) = crc & 0xFF;
177
178 ret = __nci_spi_send(nspi, skb, 0);
179
180 kfree_skb(skb);
181
182 return ret;
183}
184
185static struct sk_buff *__nci_spi_read(struct nci_spi *nspi)
186{
187 struct sk_buff *skb;
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;
192 int ret;
193
194 spi_message_init(&m);
195
196 memset(&tx, 0, sizeof(struct spi_transfer));
197 req[0] = NCI_SPI_DIRECT_READ;
198 req[1] = nspi->acknowledge_mode;
199 tx.tx_buf = req;
200 tx.len = 2;
201 tx.cs_change = 0;
202 tx.speed_hz = nspi->xfer_speed_hz;
203 spi_message_add_tail(&tx, &m);
204
205 memset(&rx, 0, sizeof(struct spi_transfer));
206 rx.rx_buf = resp_hdr;
207 rx.len = 2;
208 rx.cs_change = 1;
209 rx.speed_hz = nspi->xfer_speed_hz;
210 spi_message_add_tail(&rx, &m);
211
212 ret = spi_sync(nspi->spi, &m);
213 if (ret)
214 return NULL;
215
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;
219 else
220 rx_len = (resp_hdr[0] << 8) | resp_hdr[1];
221
222 skb = nci_skb_alloc(nspi->ndev, rx_len, GFP_KERNEL);
223 if (!skb)
224 return NULL;
225
226 spi_message_init(&m);
227
228 memset(&rx, 0, sizeof(struct spi_transfer));
229 rx.rx_buf = skb_put(skb, rx_len);
230 rx.len = rx_len;
231 rx.cs_change = 0;
232 rx.delay_usecs = nspi->xfer_udelay;
233 rx.speed_hz = nspi->xfer_speed_hz;
234 spi_message_add_tail(&rx, &m);
235
236 ret = spi_sync(nspi->spi, &m);
237 if (ret)
238 goto receive_error;
239
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];
243 }
244
245 return skb;
246
247receive_error:
248 kfree_skb(skb);
249
250 return NULL;
251}
252
253static int nci_spi_check_crc(struct sk_buff *skb)
254{
255 u16 crc_data = (skb->data[skb->len - 2] << 8) |
256 skb->data[skb->len - 1];
257 int ret;
258
259 ret = (crc_ccitt(CRC_INIT, skb->data, skb->len - NCI_SPI_CRC_LEN)
260 == crc_data);
261
262 skb_trim(skb, skb->len - NCI_SPI_CRC_LEN);
263
264 return ret;
265}
266
267static u8 nci_spi_get_ack(struct sk_buff *skb)
268{
269 u8 ret;
270
271 ret = skb->data[0] >> NCI_SPI_ACK_SHIFT;
272
273 /* Remove NFCC part of the header: ACK, NACK and MSB payload len */
274 skb_pull(skb, 2);
275
276 return ret;
277}
278
279/**
280 * nci_spi_read - read frame from NCI SPI drivers
281 *
282 * @nspi: The nci spi
283 * Context: can sleep
284 *
285 * This call may only be used from a context that may sleep. The sleep
286 * is non-interruptible, and has no timeout.
287 *
288 * It returns an allocated skb containing the frame on success, or NULL.
289 */
290struct sk_buff *nci_spi_read(struct nci_spi *nspi)
291{
292 struct sk_buff *skb;
293
294 /* Retrieve frame from SPI */
295 skb = __nci_spi_read(nspi);
296 if (!skb)
297 goto done;
298
299 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
300 if (!nci_spi_check_crc(skb)) {
301 send_acknowledge(nspi, ACKNOWLEDGE_NACK);
302 goto done;
303 }
304
305 /* In case of acknowledged mode: if ACK or NACK received,
306 * unblock completion of latest frame sent.
307 */
308 nspi->req_result = nci_spi_get_ack(skb);
309 if (nspi->req_result)
310 complete(&nspi->req_completion);
311 }
312
313 /* If there is no payload (ACK/NACK only frame),
314 * free the socket buffer
315 */
316 if (!skb->len) {
317 kfree_skb(skb);
318 skb = NULL;
319 goto done;
320 }
321
322 if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED)
323 send_acknowledge(nspi, ACKNOWLEDGE_ACK);
324
325done:
326
327 return skb;
328}
329EXPORT_SYMBOL_GPL(nci_spi_read);
330
331MODULE_LICENSE("GPL");
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
30static 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
57int 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
107done:
108 kfree_skb(skb);
109
110 return ret;
111}
112EXPORT_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 */
124struct 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}
144EXPORT_SYMBOL_GPL(nci_spi_allocate_spi);
145
146static 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
173static 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
236receive_error:
237 kfree_skb(skb);
238
239 return NULL;
240}
241
242static 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
256static 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 */
279struct 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
314done:
315
316 return skb;
317}
318EXPORT_SYMBOL_GPL(nci_spi_read);
319
320MODULE_LICENSE("GPL");