[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;

	memset(&t, 0, sizeof(struct spi_transfer));
	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);

	memset(&tx, 0, sizeof(struct spi_transfer));
	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);

	memset(&rx, 0, sizeof(struct spi_transfer));
	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);

	memset(&rx, 0, sizeof(struct spi_transfer));
	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
	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>
	23	#include <linux/crc-ccitt.h>
	24	#include <linux/nfc.h>
	25	#include <net/nfc/nci_core.h>
	26
	27	#define NCI_SPI_ACK_SHIFT 6
	28	#define NCI_SPI_MSB_PAYLOAD_MASK 0x3F
	29
	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
	42	static int __nci_spi_send(struct nci_spi nspi, struct sk_buff skb)
	43	{
	44	struct spi_message m;
	45	struct spi_transfer t;
	46
	47	memset(&t, 0, sizeof(struct spi_transfer));
	48	t.tx_buf = skb->data;
	49	t.len = skb->len;
	50	t.cs_change = 0;
	51	t.delay_usecs = nspi->xfer_udelay;
	52
	53	spi_message_init(&m);
	54	spi_message_add_tail(&t, &m);
	55
	56	return spi_sync(nspi->spi, &m);
	57	}
	58
	59	int nci_spi_send(struct nci_spi nspi, 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	nspi->ops->deassert_int(nspi);
	67
	68	/* add the NCI SPI header to the start of the buffer */
	69	hdr = skb_push(skb, NCI_SPI_HDR_LEN);
	70	hdr[0] = NCI_SPI_DIRECT_WRITE;
	71	hdr[1] = nspi->acknowledge_mode;
	72	hdr[2] = payload_len >> 8;
	73	hdr[3] = payload_len & 0xFF;
	74
	75	if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
	76	u16 crc;
	77
	78	crc = crc_ccitt(CRC_INIT, skb->data, skb->len);
	79	*skb_put(skb, 1) = crc >> 8;
	80	*skb_put(skb, 1) = crc & 0xFF;
	81	}
	82
	83	ret = __nci_spi_send(nspi, skb);
	84
	85	kfree_skb(skb);
	86	nspi->ops->assert_int(nspi);
	87
	88	if (ret != 0 \|\| nspi->acknowledge_mode == NCI_SPI_CRC_DISABLED)
	89	goto done;
	90
	91	init_completion(&nspi->req_completion);
	92	completion_rc = wait_for_completion_interruptible_timeout(
	93	&nspi->req_completion,
	94	NCI_SPI_SEND_TIMEOUT);
	95
	96	if (completion_rc <= 0 \|\| nspi->req_result == ACKNOWLEDGE_NACK)
	97	ret = -EIO;
	98
	99	done:
	100	return ret;
	101	}
	102	EXPORT_SYMBOL_GPL(nci_spi_send);
	103
	104	/* ---- Interface to NCI SPI drivers ---- */
	105
	106	/**
	107	* nci_spi_allocate_spi - allocate a new nci spi
	108	*
	109	* @spi: SPI device
	110	* @ops: device operations
	111	* @acknowledge_mode: Acknowledge mode used by the NFC device
	112	* @delay: delay between transactions in us
	113	* @ndev: nci dev to send incoming nci frames to
	114	*/
	115	struct nci_spi nci_spi_allocate_spi(struct spi_device spi,
	116	struct nci_spi_ops *ops,
	117	u8 acknowledge_mode, unsigned int delay,
	118	struct nci_dev *ndev)
	119	{
	120	struct nci_spi *nspi;
	121
	122	if (!ops->assert_int \|\| !ops->deassert_int)
	123	return NULL;
	124
	125	nspi = devm_kzalloc(&spi->dev, sizeof(struct nci_spi), GFP_KERNEL);
	126	if (!nspi)
	127	return NULL;
	128
	129	nspi->ops = ops;
	130	nspi->acknowledge_mode = acknowledge_mode;
	131	nspi->xfer_udelay = delay;
	132
	133	nspi->spi = spi;
	134	nspi->ndev = ndev;
	135
	136	return nspi;
	137	}
	138	EXPORT_SYMBOL_GPL(nci_spi_allocate_spi);
	139
	140	static int send_acknowledge(struct nci_spi *nspi, u8 acknowledge)
	141	{
	142	struct sk_buff *skb;
	143	unsigned char *hdr;
	144	u16 crc;
	145	int ret;
	146
	147	skb = nci_skb_alloc(nspi->ndev, 0, GFP_KERNEL);
	148
	149	/* add the NCI SPI header to the start of the buffer */
	150	hdr = skb_push(skb, NCI_SPI_HDR_LEN);
	151	hdr[0] = NCI_SPI_DIRECT_WRITE;
	152	hdr[1] = NCI_SPI_CRC_ENABLED;
	153	hdr[2] = acknowledge << NCI_SPI_ACK_SHIFT;
	154	hdr[3] = 0;
	155
	156	crc = crc_ccitt(CRC_INIT, skb->data, skb->len);
	157	*skb_put(skb, 1) = crc >> 8;
	158	*skb_put(skb, 1) = crc & 0xFF;
	159
	160	ret = __nci_spi_send(nspi, skb);
	161
	162	kfree_skb(skb);
	163
	164	return ret;
	165	}
	166
	167	static struct sk_buff __nci_spi_recv_frame(struct nci_spi nspi)
	168	{
	169	struct sk_buff *skb;
	170	struct spi_message m;
	171	unsigned char req[2], resp_hdr[2];
	172	struct spi_transfer tx, rx;
	173	unsigned short rx_len = 0;
	174	int ret;
	175
	176	spi_message_init(&m);
	177
	178	memset(&tx, 0, sizeof(struct spi_transfer));
	179	req[0] = NCI_SPI_DIRECT_READ;
	180	req[1] = nspi->acknowledge_mode;
	181	tx.tx_buf = req;
	182	tx.len = 2;
	183	tx.cs_change = 0;
	184	spi_message_add_tail(&tx, &m);
	185
	186	memset(&rx, 0, sizeof(struct spi_transfer));
	187	rx.rx_buf = resp_hdr;
	188	rx.len = 2;
	189	rx.cs_change = 1;
	190	spi_message_add_tail(&rx, &m);
	191
	192	ret = spi_sync(nspi->spi, &m);
	193
	194	if (ret)
	195	return NULL;
	196
	197	if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED)
	198	rx_len = ((resp_hdr[0] & NCI_SPI_MSB_PAYLOAD_MASK) << 8) +
	199	resp_hdr[1] + NCI_SPI_CRC_LEN;
	200	else
	201	rx_len = (resp_hdr[0] << 8) \| resp_hdr[1];
	202
	203	skb = nci_skb_alloc(nspi->ndev, rx_len, GFP_KERNEL);
	204	if (!skb)
	205	return NULL;
	206
	207	spi_message_init(&m);
	208
	209	memset(&rx, 0, sizeof(struct spi_transfer));
	210	rx.rx_buf = skb_put(skb, rx_len);
	211	rx.len = rx_len;
	212	rx.cs_change = 0;
	213	rx.delay_usecs = nspi->xfer_udelay;
	214	spi_message_add_tail(&rx, &m);
	215
	216	ret = spi_sync(nspi->spi, &m);
	217
	218	if (ret)
	219	goto receive_error;
	220
	221	if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
	222	*skb_push(skb, 1) = resp_hdr[1];
	223	*skb_push(skb, 1) = resp_hdr[0];
	224	}
	225
	226	return skb;
	227
	228	receive_error:
	229	kfree_skb(skb);
	230
	231	return NULL;
	232	}
	233
	234	static int nci_spi_check_crc(struct sk_buff *skb)
	235	{
	236	u16 crc_data = (skb->data[skb->len - 2] << 8) \|
	237	skb->data[skb->len - 1];
	238	int ret;
	239
	240	ret = (crc_ccitt(CRC_INIT, skb->data, skb->len - NCI_SPI_CRC_LEN)
	241	== crc_data);
	242
	243	skb_trim(skb, skb->len - NCI_SPI_CRC_LEN);
	244
	245	return ret;
	246	}
	247
	248	static u8 nci_spi_get_ack(struct sk_buff *skb)
	249	{
	250	u8 ret;
	251
	252	ret = skb->data[0] >> NCI_SPI_ACK_SHIFT;
	253
	254	/* Remove NFCC part of the header: ACK, NACK and MSB payload len */
	255	skb_pull(skb, 2);
	256
	257	return ret;
	258	}
	259
	260	/**
	261	* nci_spi_recv_frame - receive frame from NCI SPI drivers
	262	*
	263	* @nspi: The nci spi
	264	* Context: can sleep
	265	*
	266	* This call may only be used from a context that may sleep. The sleep
	267	* is non-interruptible, and has no timeout.
	268	*
	269	* It returns zero on success, else a negative error code.
	270	*/
	271	int nci_spi_recv_frame(struct nci_spi *nspi)
	272	{
	273	struct sk_buff *skb;
	274	int ret = 0;
	275
	276	nspi->ops->deassert_int(nspi);
	277
	278	/* Retrieve frame from SPI */
	279	skb = __nci_spi_recv_frame(nspi);
	280	if (!skb) {
	281	ret = -EIO;
	282	goto done;
	283	}
	284
	285	if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
	286	if (!nci_spi_check_crc(skb)) {
	287	send_acknowledge(nspi, ACKNOWLEDGE_NACK);
	288	goto done;
	289	}
	290
	291	/* In case of acknowledged mode: if ACK or NACK received,
	292	* unblock completion of latest frame sent.
	293	*/
	294	nspi->req_result = nci_spi_get_ack(skb);
	295	if (nspi->req_result)
	296	complete(&nspi->req_completion);
	297	}
	298
	299	/* If there is no payload (ACK/NACK only frame),
	300	* free the socket buffer
	301	*/
	302	if (skb->len == 0) {
	303	kfree_skb(skb);
	304	goto done;
	305	}
	306
	307	if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED)
	308	send_acknowledge(nspi, ACKNOWLEDGE_ACK);
	309
	310	/* Forward skb to NCI core layer */
	311	ret = nci_recv_frame(nspi->ndev, skb);
	312
	313	done:
	314	nspi->ops->assert_int(nspi);
	315
	316	return ret;
	317	}
	318	EXPORT_SYMBOL_GPL(nci_spi_recv_frame);