net/nfc/nci/spi.c - maze/linux - Git at Google

 /*
  * 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 <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,
 			  int cs_change)
 {
 	struct spi_message m;
 	struct spi_transfer t;

 	memset(&t, 0, sizeof(struct spi_transfer));
 	/* a NULL skb means we just want the SPI chip select line to raise */
 	if (skb) {
 		t.tx_buf = skb->data;
 		t.len = skb->len;
 	} else {
 		/* still set tx_buf non NULL to make the driver happy */
 		t.tx_buf = &t;
 		t.len = 0;
 	}
 	t.cs_change = cs_change;
 	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 completion *write_handshake_completion,
 		 struct sk_buff *skb)
 {
 	unsigned int payload_len = skb->len;
 	unsigned char *hdr;
 	int ret;
 	long completion_rc;

 	/* 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;
 	}

 	if (write_handshake_completion)	{
 		/* Trick SPI driver to raise chip select */
 		ret = __nci_spi_send(nspi, NULL, 1);
 		if (ret)
 			goto done;

 		/* wait for NFC chip hardware handshake to complete */
 		if (wait_for_completion_timeout(write_handshake_completion,
 						msecs_to_jiffies(1000)) == 0) {
 			ret = -ETIME;
 			goto done;
 		}
 	}

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

 	reinit_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:
 	kfree_skb(skb);

 	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
  * @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,
 				     u8 acknowledge_mode, unsigned int delay,
 				     struct nci_dev *ndev)
 {
 	struct nci_spi *nspi;

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

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

 	nspi->spi = spi;
 	nspi->ndev = ndev;
 	init_completion(&nspi->req_completion);

 	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, 0);

 	kfree_skb(skb);

 	return ret;
 }

 static struct sk_buff *__nci_spi_read(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_read - read 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 an allocated skb containing the frame on success, or NULL.
  */
 struct sk_buff *nci_spi_read(struct nci_spi *nspi)
 {
 	struct sk_buff *skb;

 	/* Retrieve frame from SPI */
 	skb = __nci_spi_read(nspi);
 	if (!skb)
 		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) {
 		kfree_skb(skb);
 		skb = NULL;
 		goto done;
 	}

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

 done:

 	return skb;
 }
 EXPORT_SYMBOL_GPL(nci_spi_read);
	/*
	* 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 <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,
	int cs_change)
	{
	struct spi_message m;
	struct spi_transfer t;

	memset(&t, 0, sizeof(struct spi_transfer));
	/* a NULL skb means we just want the SPI chip select line to raise */
	if (skb) {
	t.tx_buf = skb->data;
	t.len = skb->len;
	} else {
	/* still set tx_buf non NULL to make the driver happy */
	t.tx_buf = &t;
	t.len = 0;
	}
	t.cs_change = cs_change;
	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 completion *write_handshake_completion,
	struct sk_buff *skb)
	{
	unsigned int payload_len = skb->len;
	unsigned char *hdr;
	int ret;
	long completion_rc;

	/* 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;
	}

	if (write_handshake_completion) {
	/* Trick SPI driver to raise chip select */
	ret = __nci_spi_send(nspi, NULL, 1);
	if (ret)
	goto done;

	/* wait for NFC chip hardware handshake to complete */
	if (wait_for_completion_timeout(write_handshake_completion,
	msecs_to_jiffies(1000)) == 0) {
	ret = -ETIME;
	goto done;
	}
	}

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

	reinit_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:
	kfree_skb(skb);

	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
	* @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,
	u8 acknowledge_mode, unsigned int delay,
	struct nci_dev *ndev)
	{
	struct nci_spi *nspi;

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

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

	nspi->spi = spi;
	nspi->ndev = ndev;
	init_completion(&nspi->req_completion);

	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, 0);

	kfree_skb(skb);

	return ret;
	}

	static struct sk_buff __nci_spi_read(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_read - read 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 an allocated skb containing the frame on success, or NULL.
	*/
	struct sk_buff nci_spi_read(struct nci_spi nspi)
	{
	struct sk_buff *skb;

	/* Retrieve frame from SPI */
	skb = __nci_spi_read(nspi);
	if (!skb)
	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) {
	kfree_skb(skb);
	skb = NULL;
	goto done;
	}

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

	done:

	return skb;
	}
	EXPORT_SYMBOL_GPL(nci_spi_read);