From 52409fae3e4b8d16b68b61902fc09075cd97b75d Mon Sep 17 00:00:00 2001 From: Dominik Sliwa Date: Sun, 2 Jul 2017 16:41:37 +0200 Subject: Backports generated from 4.11 kernel Initial commit. Signed-off-by: Dominik Sliwa --- net/nfc/nci/spi.c | 331 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 331 insertions(+) create mode 100644 net/nfc/nci/spi.c (limited to 'net/nfc/nci/spi.c') diff --git a/net/nfc/nci/spi.c b/net/nfc/nci/spi.c new file mode 100644 index 0000000..d904cd2 --- /dev/null +++ b/net/nfc/nci/spi.c @@ -0,0 +1,331 @@ +/* + * 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 + +#include +#include +#include +#include + +#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; + t.speed_hz = nspi->xfer_speed_hz; + + 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; + /* Use controller max SPI speed by default */ + nspi->xfer_speed_hz = 0; + 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; + tx.speed_hz = nspi->xfer_speed_hz; + 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; + rx.speed_hz = nspi->xfer_speed_hz; + 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; + rx.speed_hz = nspi->xfer_speed_hz; + 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); + +MODULE_LICENSE("GPL"); -- cgit v1.2.3