1 files changed, 322 insertions, 0 deletions
diff --git a/net/nfc/nci/spi.c b/net/nfc/nci/spi.c
new file mode 100644
index 000000000..ec250e777
--- /dev/null
+++ b/net/nfc/nci/spi.c
@@ -0,0 +1,322 @@
+/*
+ * 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);