diff options
Diffstat (limited to 'net/nfc/nci/spi.c')
| -rw-r--r-- | net/nfc/nci/spi.c | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/net/nfc/nci/spi.c b/net/nfc/nci/spi.c index 6258461e6998..70afc387a965 100644 --- a/net/nfc/nci/spi.c +++ b/net/nfc/nci/spi.c @@ -26,6 +26,8 @@ #define NCI_SPI_HDR_LEN 4 #define NCI_SPI_CRC_LEN 2 +#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) @@ -203,3 +205,175 @@ void nci_spi_unregister_device(struct nci_spi_dev *ndev) nci_unregister_device(ndev->nci_dev); } EXPORT_SYMBOL_GPL(nci_spi_unregister_device); + +static int send_acknowledge(struct nci_spi_dev *ndev, u8 acknowledge) +{ + struct sk_buff *skb; + unsigned char *hdr; + u16 crc; + int ret; + + skb = nci_skb_alloc(ndev->nci_dev, 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(ndev, skb); + + kfree_skb(skb); + + return ret; +} + +static struct sk_buff *__nci_spi_recv_frame(struct nci_spi_dev *ndev) +{ + 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] = ndev->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(ndev->spi, &m); + + if (ret) + return NULL; + + if (ndev->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(ndev->nci_dev, 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 = ndev->xfer_udelay; + spi_message_add_tail(&rx, &m); + ret = spi_sync(ndev->spi, &m); + + if (ret) + goto receive_error; + + if (ndev->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 + * + * @ndev: The nci spi device + * 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_dev *ndev) +{ + struct sk_buff *skb; + int ret = 0; + + ndev->ops->deassert_int(ndev); + + /* Retrieve frame from SPI */ + skb = __nci_spi_recv_frame(ndev); + if (!skb) { + ret = -EIO; + goto done; + } + + if (ndev->acknowledge_mode == NCI_SPI_CRC_ENABLED) { + if (!nci_spi_check_crc(skb)) { + send_acknowledge(ndev, ACKNOWLEDGE_NACK); + goto done; + } + + /* In case of acknowledged mode: if ACK or NACK received, + * unblock completion of latest frame sent. + */ + ndev->req_result = nci_spi_get_ack(skb); + if (ndev->req_result) + complete(&ndev->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 (ndev->acknowledge_mode == NCI_SPI_CRC_ENABLED) + send_acknowledge(ndev, ACKNOWLEDGE_ACK); + + /* Forward skb to NCI core layer */ + ret = nci_recv_frame(ndev->nci_dev, skb); + +done: + ndev->ops->assert_int(ndev); + + return ret; +} +EXPORT_SYMBOL_GPL(nci_spi_recv_frame); |