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authorFrederic Danis <frederic.danis@linux.intel.com>2013-05-29 15:35:03 +0200
committerSamuel Ortiz <sameo@linux.intel.com>2013-06-14 13:44:15 +0200
commitee9596d467e4d05c77a8c883aeeb5b74d1a3cd31 (patch)
tree256dad6d872ced15c55723fcdccfcdcf3d87734a /net/nfc
parent8a00a61b0ef2bfd1b468dd20c0d0b1a94a8f7475 (diff)
NFC: Add NCI over SPI send
Before any operation, driver interruption is de-asserted to prevent race condition between TX and RX. The NCI over SPI header is added in front of NCI packet. If acknowledged mode is set, CRC-16-CCITT is added to the packet. Then the packet is forwarded to SPI module to be sent. A delay after the transaction is added. This delay is determined by the driver during nci_spi_allocate_device() call and can be 0. After data has been sent, driver interruption is re-asserted. If acknowledged mode is set, nci_spi_send will block until acknowledgment is received. Signed-off-by: Frederic Danis <frederic.danis@linux.intel.com> Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Diffstat (limited to 'net/nfc')
-rw-r--r--net/nfc/nci/spi.c71
1 files changed, 70 insertions, 1 deletions
diff --git a/net/nfc/nci/spi.c b/net/nfc/nci/spi.c
index ebcdba51418c..6258461e6998 100644
--- a/net/nfc/nci/spi.c
+++ b/net/nfc/nci/spi.c
@@ -20,12 +20,25 @@
#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_HDR_LEN 4
#define NCI_SPI_CRC_LEN 2
+#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_open(struct nci_dev *nci_dev)
{
struct nci_spi_dev *ndev = nci_get_drvdata(nci_dev);
@@ -40,9 +53,65 @@ static int nci_spi_close(struct nci_dev *nci_dev)
return ndev->ops->close(ndev);
}
+static int __nci_spi_send(struct nci_spi_dev *ndev, 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 = ndev->xfer_udelay;
+
+ spi_message_init(&m);
+ spi_message_add_tail(&t, &m);
+
+ return spi_sync(ndev->spi, &m);
+}
+
static int nci_spi_send(struct nci_dev *nci_dev, struct sk_buff *skb)
{
- return 0;
+ struct nci_spi_dev *ndev = nci_get_drvdata(nci_dev);
+ unsigned int payload_len = skb->len;
+ unsigned char *hdr;
+ int ret;
+ long completion_rc;
+
+ ndev->ops->deassert_int(ndev);
+
+ /* 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] = ndev->acknowledge_mode;
+ hdr[2] = payload_len >> 8;
+ hdr[3] = payload_len & 0xFF;
+
+ if (ndev->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(ndev, skb);
+
+ kfree_skb(skb);
+ ndev->ops->assert_int(ndev);
+
+ if (ret != 0 || ndev->acknowledge_mode == NCI_SPI_CRC_DISABLED)
+ goto done;
+
+ init_completion(&ndev->req_completion);
+ completion_rc =
+ wait_for_completion_interruptible_timeout(&ndev->req_completion,
+ NCI_SPI_SEND_TIMEOUT);
+
+ if (completion_rc <= 0 || ndev->req_result == ACKNOWLEDGE_NACK)
+ ret = -EIO;
+
+done:
+ return ret;
}
static struct nci_ops nci_spi_ops = {

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