[deliverable/linux.git] / net / nfc / nci / spi.c

/*
 * Copyright (C) 2013  Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */

#define pr_fmt(fmt) "nci_spi: %s: " fmt, __func__

#include <linux/export.h>
#include <linux/spi/spi.h>
#include <linux/crc-ccitt.h>
#include <linux/nfc.h>
#include <net/nfc/nci_core.h>

#define NCI_SPI_ACK_SHIFT		6
#define NCI_SPI_MSB_PAYLOAD_MASK	0x3F

#define NCI_SPI_SEND_TIMEOUT	(NCI_CMD_TIMEOUT > NCI_DATA_TIMEOUT ? \
					NCI_CMD_TIMEOUT : NCI_DATA_TIMEOUT)

#define NCI_SPI_DIRECT_WRITE	0x01
#define NCI_SPI_DIRECT_READ	0x02

#define ACKNOWLEDGE_NONE	0
#define ACKNOWLEDGE_ACK		1
#define ACKNOWLEDGE_NACK	2

#define CRC_INIT		0xFFFF

static int __nci_spi_send(struct nci_spi *nspi, struct sk_buff *skb)
{
	struct spi_message m;
	struct spi_transfer t;

	t.tx_buf = skb->data;
	t.len = skb->len;
	t.cs_change = 0;
	t.delay_usecs = nspi->xfer_udelay;

	spi_message_init(&m);
	spi_message_add_tail(&t, &m);

	return spi_sync(nspi->spi, &m);
}

int nci_spi_send(struct nci_spi *nspi, struct sk_buff *skb)
{
	unsigned int payload_len = skb->len;
	unsigned char *hdr;
	int ret;
	long completion_rc;

	nspi->ops->deassert_int(nspi);

	/* add the NCI SPI header to the start of the buffer */
	hdr = skb_push(skb, NCI_SPI_HDR_LEN);
	hdr[0] = NCI_SPI_DIRECT_WRITE;
	hdr[1] = nspi->acknowledge_mode;
	hdr[2] = payload_len >> 8;
	hdr[3] = payload_len & 0xFF;

	if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
		u16 crc;

		crc = crc_ccitt(CRC_INIT, skb->data, skb->len);
		*skb_put(skb, 1) = crc >> 8;
		*skb_put(skb, 1) = crc & 0xFF;
	}

	ret = __nci_spi_send(nspi, skb);

	kfree_skb(skb);
	nspi->ops->assert_int(nspi);

	if (ret != 0 || nspi->acknowledge_mode == NCI_SPI_CRC_DISABLED)
		goto done;

	init_completion(&nspi->req_completion);
	completion_rc =	wait_for_completion_interruptible_timeout(
							&nspi->req_completion,
							NCI_SPI_SEND_TIMEOUT);

	if (completion_rc <= 0 || nspi->req_result == ACKNOWLEDGE_NACK)
		ret = -EIO;

done:
	return ret;
}
EXPORT_SYMBOL_GPL(nci_spi_send);

/* ---- Interface to NCI SPI drivers ---- */

/**
 * nci_spi_allocate_spi - allocate a new nci spi
 *
 * @spi: SPI device
 * @ops: device operations
 * @acknowledge_mode: Acknowledge mode used by the NFC device
 * @delay: delay between transactions in us
 * @ndev: nci dev to send incoming nci frames to
 */
struct nci_spi *nci_spi_allocate_spi(struct spi_device *spi,
				     struct nci_spi_ops *ops,
				     u8 acknowledge_mode, unsigned int delay,
				     struct nci_dev *ndev)
{
	struct nci_spi *nspi;

	if (!ops->assert_int || !ops->deassert_int)
		return NULL;

	nspi = devm_kzalloc(&spi->dev, sizeof(struct nci_spi), GFP_KERNEL);
	if (!nspi)
		return NULL;

	nspi->ops = ops;
	nspi->acknowledge_mode = acknowledge_mode;
	nspi->xfer_udelay = delay;

	nspi->spi = spi;
	nspi->ndev = ndev;

	return nspi;
}
EXPORT_SYMBOL_GPL(nci_spi_allocate_spi);

static int send_acknowledge(struct nci_spi *nspi, u8 acknowledge)
{
	struct sk_buff *skb;
	unsigned char *hdr;
	u16 crc;
	int ret;

	skb = nci_skb_alloc(nspi->ndev, 0, GFP_KERNEL);

	/* add the NCI SPI header to the start of the buffer */
	hdr = skb_push(skb, NCI_SPI_HDR_LEN);
	hdr[0] = NCI_SPI_DIRECT_WRITE;
	hdr[1] = NCI_SPI_CRC_ENABLED;
	hdr[2] = acknowledge << NCI_SPI_ACK_SHIFT;
	hdr[3] = 0;

	crc = crc_ccitt(CRC_INIT, skb->data, skb->len);
	*skb_put(skb, 1) = crc >> 8;
	*skb_put(skb, 1) = crc & 0xFF;

	ret = __nci_spi_send(nspi, skb);

	kfree_skb(skb);

	return ret;
}

static struct sk_buff *__nci_spi_recv_frame(struct nci_spi *nspi)
{
	struct sk_buff *skb;
	struct spi_message m;
	unsigned char req[2], resp_hdr[2];
	struct spi_transfer tx, rx;
	unsigned short rx_len = 0;
	int ret;

	spi_message_init(&m);
	req[0] = NCI_SPI_DIRECT_READ;
	req[1] = nspi->acknowledge_mode;
	tx.tx_buf = req;
	tx.len = 2;
	tx.cs_change = 0;
	spi_message_add_tail(&tx, &m);
	rx.rx_buf = resp_hdr;
	rx.len = 2;
	rx.cs_change = 1;
	spi_message_add_tail(&rx, &m);
	ret = spi_sync(nspi->spi, &m);

	if (ret)
		return NULL;

	if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED)
		rx_len = ((resp_hdr[0] & NCI_SPI_MSB_PAYLOAD_MASK) << 8) +
				resp_hdr[1] + NCI_SPI_CRC_LEN;
	else
		rx_len = (resp_hdr[0] << 8) | resp_hdr[1];

	skb = nci_skb_alloc(nspi->ndev, rx_len, GFP_KERNEL);
	if (!skb)
		return NULL;

	spi_message_init(&m);
	rx.rx_buf = skb_put(skb, rx_len);
	rx.len = rx_len;
	rx.cs_change = 0;
	rx.delay_usecs = nspi->xfer_udelay;
	spi_message_add_tail(&rx, &m);
	ret = spi_sync(nspi->spi, &m);

	if (ret)
		goto receive_error;

	if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
		*skb_push(skb, 1) = resp_hdr[1];
		*skb_push(skb, 1) = resp_hdr[0];
	}

	return skb;

receive_error:
	kfree_skb(skb);

	return NULL;
}

static int nci_spi_check_crc(struct sk_buff *skb)
{
	u16 crc_data = (skb->data[skb->len - 2] << 8) |
			skb->data[skb->len - 1];
	int ret;

	ret = (crc_ccitt(CRC_INIT, skb->data, skb->len - NCI_SPI_CRC_LEN)
			== crc_data);

	skb_trim(skb, skb->len - NCI_SPI_CRC_LEN);

	return ret;
}

static u8 nci_spi_get_ack(struct sk_buff *skb)
{
	u8 ret;

	ret = skb->data[0] >> NCI_SPI_ACK_SHIFT;

	/* Remove NFCC part of the header: ACK, NACK and MSB payload len */
	skb_pull(skb, 2);

	return ret;
}

/**
 * nci_spi_recv_frame - receive frame from NCI SPI drivers
 *
 * @nspi: The nci spi
 * Context: can sleep
 *
 * This call may only be used from a context that may sleep.  The sleep
 * is non-interruptible, and has no timeout.
 *
 * It returns zero on success, else a negative error code.
 */
int nci_spi_recv_frame(struct nci_spi *nspi)
{
	struct sk_buff *skb;
	int ret = 0;

	nspi->ops->deassert_int(nspi);

	/* Retrieve frame from SPI */
	skb = __nci_spi_recv_frame(nspi);
	if (!skb) {
		ret = -EIO;
		goto done;
	}

	if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
		if (!nci_spi_check_crc(skb)) {
			send_acknowledge(nspi, ACKNOWLEDGE_NACK);
			goto done;
		}

		/* In case of acknowledged mode: if ACK or NACK received,
		 * unblock completion of latest frame sent.
		 */
		nspi->req_result = nci_spi_get_ack(skb);
		if (nspi->req_result)
			complete(&nspi->req_completion);
	}

	/* If there is no payload (ACK/NACK only frame),
	 * free the socket buffer
	 */
	if (skb->len == 0) {
		kfree_skb(skb);
		goto done;
	}

	if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED)
		send_acknowledge(nspi, ACKNOWLEDGE_ACK);

	/* Forward skb to NCI core layer */
	ret = nci_recv_frame(nspi->ndev, skb);

done:
	nspi->ops->assert_int(nspi);

	return ret;
}
EXPORT_SYMBOL_GPL(nci_spi_recv_frame);
Commit	Line	Data
8a00a61b FD	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/export.h>
	22	#include <linux/spi/spi.h>
ee9596d4	23	#include <linux/crc-ccitt.h>
8a00a61b FD	24	#include <linux/nfc.h>
	25	#include <net/nfc/nci_core.h>
	26
391d8a2d FD	27	#define NCI_SPI_ACK_SHIFT 6
391d8a2d FD	28	#define NCI_SPI_MSB_PAYLOAD_MASK 0x3F
8a00a61b	29
ee9596d4 FD	30	#define NCI_SPI_SEND_TIMEOUT (NCI_CMD_TIMEOUT > NCI_DATA_TIMEOUT ? \
	31	NCI_CMD_TIMEOUT : NCI_DATA_TIMEOUT)
	32
	33	#define NCI_SPI_DIRECT_WRITE 0x01
	34	#define NCI_SPI_DIRECT_READ 0x02
	35
	36	#define ACKNOWLEDGE_NONE 0
	37	#define ACKNOWLEDGE_ACK 1
	38	#define ACKNOWLEDGE_NACK 2
	39
	40	#define CRC_INIT 0xFFFF
	41
fa544fff	42	static int __nci_spi_send(struct nci_spi nspi, struct sk_buff skb)
ee9596d4 FD	43	{
	44	struct spi_message m;
	45	struct spi_transfer t;
	46
	47	t.tx_buf = skb->data;
	48	t.len = skb->len;
	49	t.cs_change = 0;
fa544fff	50	t.delay_usecs = nspi->xfer_udelay;
ee9596d4 FD	51
	52	spi_message_init(&m);
	53	spi_message_add_tail(&t, &m);
	54
fa544fff	55	return spi_sync(nspi->spi, &m);
ee9596d4 FD	56	}
ee9596d4 FD	57
fa544fff	58	int nci_spi_send(struct nci_spi nspi, struct sk_buff skb)
8a00a61b	59	{
ee9596d4 FD	60	unsigned int payload_len = skb->len;
	61	unsigned char *hdr;
	62	int ret;
	63	long completion_rc;
	64
fa544fff	65	nspi->ops->deassert_int(nspi);
ee9596d4 FD	66
	67	/* add the NCI SPI header to the start of the buffer */
	68	hdr = skb_push(skb, NCI_SPI_HDR_LEN);
	69	hdr[0] = NCI_SPI_DIRECT_WRITE;
fa544fff	70	hdr[1] = nspi->acknowledge_mode;
ee9596d4 FD	71	hdr[2] = payload_len >> 8;
	72	hdr[3] = payload_len & 0xFF;
	73
fa544fff	74	if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
ee9596d4 FD	75	u16 crc;
	76
	77	crc = crc_ccitt(CRC_INIT, skb->data, skb->len);
	78	*skb_put(skb, 1) = crc >> 8;
	79	*skb_put(skb, 1) = crc & 0xFF;
	80	}
	81
fa544fff	82	ret = __nci_spi_send(nspi, skb);
ee9596d4 FD	83
ee9596d4 FD	84	kfree_skb(skb);
fa544fff	85	nspi->ops->assert_int(nspi);
ee9596d4	86
fa544fff	87	if (ret != 0 \|\| nspi->acknowledge_mode == NCI_SPI_CRC_DISABLED)
ee9596d4 FD	88	goto done;
ee9596d4 FD	89
fa544fff	90	init_completion(&nspi->req_completion);
d5937511	91	completion_rc = wait_for_completion_interruptible_timeout(
fa544fff	92	&nspi->req_completion,
d5937511	93	NCI_SPI_SEND_TIMEOUT);
ee9596d4	94
fa544fff	95	if (completion_rc <= 0 \|\| nspi->req_result == ACKNOWLEDGE_NACK)
ee9596d4 FD	96	ret = -EIO;
	97
	98	done:
	99	return ret;
8a00a61b	100	}
fa544fff	101	EXPORT_SYMBOL_GPL(nci_spi_send);
8a00a61b FD	102
	103	/* ---- Interface to NCI SPI drivers ---- */
	104
	105	/**
fa544fff	106	* nci_spi_allocate_spi - allocate a new nci spi
8a00a61b FD	107	*
	108	* @spi: SPI device
	109	* @ops: device operations
fa544fff	110	* @acknowledge_mode: Acknowledge mode used by the NFC device
8a00a61b	111	* @delay: delay between transactions in us
fa544fff	112	* @ndev: nci dev to send incoming nci frames to
8a00a61b	113	*/
fa544fff EL	114	struct nci_spi nci_spi_allocate_spi(struct spi_device spi,
	115	struct nci_spi_ops *ops,
	116	u8 acknowledge_mode, unsigned int delay,
	117	struct nci_dev *ndev)
8a00a61b	118	{
fa544fff	119	struct nci_spi *nspi;
8a00a61b	120
fa544fff	121	if (!ops->assert_int \|\| !ops->deassert_int)
8a00a61b FD	122	return NULL;
8a00a61b FD	123
fa544fff EL	124	nspi = devm_kzalloc(&spi->dev, sizeof(struct nci_spi), GFP_KERNEL);
fa544fff EL	125	if (!nspi)
8a00a61b FD	126	return NULL;
8a00a61b FD	127
fa544fff EL	128	nspi->ops = ops;
	129	nspi->acknowledge_mode = acknowledge_mode;
	130	nspi->xfer_udelay = delay;
8a00a61b	131
645d5087	132	nspi->spi = spi;
fa544fff	133	nspi->ndev = ndev;
8a00a61b	134
fa544fff	135	return nspi;
8a00a61b	136	}
fa544fff	137	EXPORT_SYMBOL_GPL(nci_spi_allocate_spi);
391d8a2d	138
fa544fff	139	static int send_acknowledge(struct nci_spi *nspi, u8 acknowledge)
391d8a2d FD	140	{
	141	struct sk_buff *skb;
	142	unsigned char *hdr;
	143	u16 crc;
	144	int ret;
	145
fa544fff	146	skb = nci_skb_alloc(nspi->ndev, 0, GFP_KERNEL);
391d8a2d FD	147
	148	/* add the NCI SPI header to the start of the buffer */
	149	hdr = skb_push(skb, NCI_SPI_HDR_LEN);
	150	hdr[0] = NCI_SPI_DIRECT_WRITE;
	151	hdr[1] = NCI_SPI_CRC_ENABLED;
	152	hdr[2] = acknowledge << NCI_SPI_ACK_SHIFT;
	153	hdr[3] = 0;
	154
	155	crc = crc_ccitt(CRC_INIT, skb->data, skb->len);
	156	*skb_put(skb, 1) = crc >> 8;
	157	*skb_put(skb, 1) = crc & 0xFF;
	158
fa544fff	159	ret = __nci_spi_send(nspi, skb);
391d8a2d FD	160
	161	kfree_skb(skb);
	162
	163	return ret;
	164	}
	165
fa544fff	166	static struct sk_buff __nci_spi_recv_frame(struct nci_spi nspi)
391d8a2d FD	167	{
	168	struct sk_buff *skb;
	169	struct spi_message m;
	170	unsigned char req[2], resp_hdr[2];
	171	struct spi_transfer tx, rx;
	172	unsigned short rx_len = 0;
	173	int ret;
	174
	175	spi_message_init(&m);
	176	req[0] = NCI_SPI_DIRECT_READ;
fa544fff	177	req[1] = nspi->acknowledge_mode;
391d8a2d FD	178	tx.tx_buf = req;
	179	tx.len = 2;
	180	tx.cs_change = 0;
	181	spi_message_add_tail(&tx, &m);
	182	rx.rx_buf = resp_hdr;
	183	rx.len = 2;
	184	rx.cs_change = 1;
	185	spi_message_add_tail(&rx, &m);
fa544fff	186	ret = spi_sync(nspi->spi, &m);
391d8a2d FD	187
	188	if (ret)
	189	return NULL;
	190
fa544fff	191	if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED)
391d8a2d FD	192	rx_len = ((resp_hdr[0] & NCI_SPI_MSB_PAYLOAD_MASK) << 8) +
	193	resp_hdr[1] + NCI_SPI_CRC_LEN;
	194	else
	195	rx_len = (resp_hdr[0] << 8) \| resp_hdr[1];
	196
fa544fff	197	skb = nci_skb_alloc(nspi->ndev, rx_len, GFP_KERNEL);
391d8a2d FD	198	if (!skb)
	199	return NULL;
	200
	201	spi_message_init(&m);
	202	rx.rx_buf = skb_put(skb, rx_len);
	203	rx.len = rx_len;
	204	rx.cs_change = 0;
fa544fff	205	rx.delay_usecs = nspi->xfer_udelay;
391d8a2d	206	spi_message_add_tail(&rx, &m);
fa544fff	207	ret = spi_sync(nspi->spi, &m);
391d8a2d FD	208
	209	if (ret)
	210	goto receive_error;
	211
fa544fff	212	if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
391d8a2d FD	213	*skb_push(skb, 1) = resp_hdr[1];
	214	*skb_push(skb, 1) = resp_hdr[0];
	215	}
	216
	217	return skb;
	218
	219	receive_error:
	220	kfree_skb(skb);
	221
	222	return NULL;
	223	}
	224
	225	static int nci_spi_check_crc(struct sk_buff *skb)
	226	{
	227	u16 crc_data = (skb->data[skb->len - 2] << 8) \|
	228	skb->data[skb->len - 1];
	229	int ret;
	230
	231	ret = (crc_ccitt(CRC_INIT, skb->data, skb->len - NCI_SPI_CRC_LEN)
	232	== crc_data);
	233
	234	skb_trim(skb, skb->len - NCI_SPI_CRC_LEN);
	235
	236	return ret;
	237	}
	238
	239	static u8 nci_spi_get_ack(struct sk_buff *skb)
	240	{
	241	u8 ret;
	242
	243	ret = skb->data[0] >> NCI_SPI_ACK_SHIFT;
	244
	245	/* Remove NFCC part of the header: ACK, NACK and MSB payload len */
	246	skb_pull(skb, 2);
	247
	248	return ret;
	249	}
	250
	251	/**
	252	* nci_spi_recv_frame - receive frame from NCI SPI drivers
	253	*
fa544fff	254	* @nspi: The nci spi
391d8a2d FD	255	* Context: can sleep
	256	*
	257	* This call may only be used from a context that may sleep. The sleep
	258	* is non-interruptible, and has no timeout.
	259	*
	260	* It returns zero on success, else a negative error code.
	261	*/
fa544fff	262	int nci_spi_recv_frame(struct nci_spi *nspi)
391d8a2d FD	263	{
	264	struct sk_buff *skb;
	265	int ret = 0;
	266
fa544fff	267	nspi->ops->deassert_int(nspi);
391d8a2d FD	268
391d8a2d FD	269	/* Retrieve frame from SPI */
fa544fff	270	skb = __nci_spi_recv_frame(nspi);
391d8a2d FD	271	if (!skb) {
	272	ret = -EIO;
	273	goto done;
	274	}
	275
fa544fff	276	if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
391d8a2d	277	if (!nci_spi_check_crc(skb)) {
fa544fff	278	send_acknowledge(nspi, ACKNOWLEDGE_NACK);
391d8a2d FD	279	goto done;
	280	}
	281
	282	/* In case of acknowledged mode: if ACK or NACK received,
	283	* unblock completion of latest frame sent.
	284	*/
fa544fff EL	285	nspi->req_result = nci_spi_get_ack(skb);
	286	if (nspi->req_result)
	287	complete(&nspi->req_completion);
391d8a2d FD	288	}
	289
	290	/* If there is no payload (ACK/NACK only frame),
	291	* free the socket buffer
	292	*/
	293	if (skb->len == 0) {
	294	kfree_skb(skb);
	295	goto done;
	296	}
	297
fa544fff EL	298	if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED)
fa544fff EL	299	send_acknowledge(nspi, ACKNOWLEDGE_ACK);
391d8a2d FD	300
391d8a2d FD	301	/* Forward skb to NCI core layer */
fa544fff	302	ret = nci_recv_frame(nspi->ndev, skb);
391d8a2d FD	303
391d8a2d FD	304	done:
fa544fff	305	nspi->ops->assert_int(nspi);
391d8a2d FD	306
	307	return ret;
	308	}
	309	EXPORT_SYMBOL_GPL(nci_spi_recv_frame);