// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2013 Intel Corporation. All rights reserved.
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*/
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#define pr_fmt(fmt) "nci_spi: %s: " fmt, __func__
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#include <linux/module.h>
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#include <linux/export.h>
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#include <linux/spi/spi.h>
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#include <linux/crc-ccitt.h>
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#include <net/nfc/nci_core.h>
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#define NCI_SPI_ACK_SHIFT 6
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#define NCI_SPI_MSB_PAYLOAD_MASK 0x3F
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#define NCI_SPI_SEND_TIMEOUT (NCI_CMD_TIMEOUT > NCI_DATA_TIMEOUT ? \
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NCI_CMD_TIMEOUT : NCI_DATA_TIMEOUT)
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#define NCI_SPI_DIRECT_WRITE 0x01
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#define NCI_SPI_DIRECT_READ 0x02
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#define ACKNOWLEDGE_NONE 0
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#define ACKNOWLEDGE_ACK 1
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#define ACKNOWLEDGE_NACK 2
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#define CRC_INIT 0xFFFF
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static int __nci_spi_send(struct nci_spi *nspi, struct sk_buff *skb,
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int cs_change)
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{
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struct spi_message m;
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struct spi_transfer t;
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memset(&t, 0, sizeof(struct spi_transfer));
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/* a NULL skb means we just want the SPI chip select line to raise */
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if (skb) {
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t.tx_buf = skb->data;
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t.len = skb->len;
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} else {
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/* still set tx_buf non NULL to make the driver happy */
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t.tx_buf = &t;
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t.len = 0;
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}
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t.cs_change = cs_change;
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t.delay.value = nspi->xfer_udelay;
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t.delay.unit = SPI_DELAY_UNIT_USECS;
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t.speed_hz = nspi->xfer_speed_hz;
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spi_message_init(&m);
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spi_message_add_tail(&t, &m);
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return spi_sync(nspi->spi, &m);
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}
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int nci_spi_send(struct nci_spi *nspi,
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struct completion *write_handshake_completion,
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struct sk_buff *skb)
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{
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unsigned int payload_len = skb->len;
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unsigned char *hdr;
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int ret;
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long completion_rc;
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/* add the NCI SPI header to the start of the buffer */
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hdr = skb_push(skb, NCI_SPI_HDR_LEN);
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hdr[0] = NCI_SPI_DIRECT_WRITE;
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hdr[1] = nspi->acknowledge_mode;
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hdr[2] = payload_len >> 8;
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hdr[3] = payload_len & 0xFF;
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if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
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u16 crc;
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crc = crc_ccitt(CRC_INIT, skb->data, skb->len);
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skb_put_u8(skb, crc >> 8);
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skb_put_u8(skb, crc & 0xFF);
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}
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if (write_handshake_completion) {
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/* Trick SPI driver to raise chip select */
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ret = __nci_spi_send(nspi, NULL, 1);
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if (ret)
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goto done;
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/* wait for NFC chip hardware handshake to complete */
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if (wait_for_completion_timeout(write_handshake_completion,
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msecs_to_jiffies(1000)) == 0) {
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ret = -ETIME;
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goto done;
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}
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}
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ret = __nci_spi_send(nspi, skb, 0);
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if (ret != 0 || nspi->acknowledge_mode == NCI_SPI_CRC_DISABLED)
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goto done;
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reinit_completion(&nspi->req_completion);
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completion_rc = wait_for_completion_interruptible_timeout(
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&nspi->req_completion,
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NCI_SPI_SEND_TIMEOUT);
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if (completion_rc <= 0 || nspi->req_result == ACKNOWLEDGE_NACK)
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ret = -EIO;
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done:
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kfree_skb(skb);
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return ret;
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}
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EXPORT_SYMBOL_GPL(nci_spi_send);
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/* ---- Interface to NCI SPI drivers ---- */
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/**
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* nci_spi_allocate_spi - allocate a new nci spi
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*
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* @spi: SPI device
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* @acknowledge_mode: Acknowledge mode used by the NFC device
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* @delay: delay between transactions in us
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* @ndev: nci dev to send incoming nci frames to
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*/
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struct nci_spi *nci_spi_allocate_spi(struct spi_device *spi,
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u8 acknowledge_mode, unsigned int delay,
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struct nci_dev *ndev)
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{
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struct nci_spi *nspi;
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nspi = devm_kzalloc(&spi->dev, sizeof(struct nci_spi), GFP_KERNEL);
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if (!nspi)
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return NULL;
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nspi->acknowledge_mode = acknowledge_mode;
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nspi->xfer_udelay = delay;
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/* Use controller max SPI speed by default */
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nspi->xfer_speed_hz = 0;
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nspi->spi = spi;
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nspi->ndev = ndev;
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init_completion(&nspi->req_completion);
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return nspi;
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}
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EXPORT_SYMBOL_GPL(nci_spi_allocate_spi);
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static int send_acknowledge(struct nci_spi *nspi, u8 acknowledge)
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{
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struct sk_buff *skb;
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unsigned char *hdr;
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u16 crc;
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int ret;
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skb = nci_skb_alloc(nspi->ndev, 0, GFP_KERNEL);
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/* add the NCI SPI header to the start of the buffer */
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hdr = skb_push(skb, NCI_SPI_HDR_LEN);
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hdr[0] = NCI_SPI_DIRECT_WRITE;
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hdr[1] = NCI_SPI_CRC_ENABLED;
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hdr[2] = acknowledge << NCI_SPI_ACK_SHIFT;
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hdr[3] = 0;
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crc = crc_ccitt(CRC_INIT, skb->data, skb->len);
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skb_put_u8(skb, crc >> 8);
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skb_put_u8(skb, crc & 0xFF);
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ret = __nci_spi_send(nspi, skb, 0);
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kfree_skb(skb);
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return ret;
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}
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static struct sk_buff *__nci_spi_read(struct nci_spi *nspi)
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{
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struct sk_buff *skb;
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struct spi_message m;
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unsigned char req[2], resp_hdr[2];
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struct spi_transfer tx, rx;
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unsigned short rx_len = 0;
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int ret;
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spi_message_init(&m);
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memset(&tx, 0, sizeof(struct spi_transfer));
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req[0] = NCI_SPI_DIRECT_READ;
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req[1] = nspi->acknowledge_mode;
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tx.tx_buf = req;
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tx.len = 2;
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tx.cs_change = 0;
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tx.speed_hz = nspi->xfer_speed_hz;
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spi_message_add_tail(&tx, &m);
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memset(&rx, 0, sizeof(struct spi_transfer));
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rx.rx_buf = resp_hdr;
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rx.len = 2;
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rx.cs_change = 1;
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rx.speed_hz = nspi->xfer_speed_hz;
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spi_message_add_tail(&rx, &m);
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ret = spi_sync(nspi->spi, &m);
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if (ret)
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return NULL;
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if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED)
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rx_len = ((resp_hdr[0] & NCI_SPI_MSB_PAYLOAD_MASK) << 8) +
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resp_hdr[1] + NCI_SPI_CRC_LEN;
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else
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rx_len = (resp_hdr[0] << 8) | resp_hdr[1];
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skb = nci_skb_alloc(nspi->ndev, rx_len, GFP_KERNEL);
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if (!skb)
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return NULL;
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spi_message_init(&m);
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memset(&rx, 0, sizeof(struct spi_transfer));
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rx.rx_buf = skb_put(skb, rx_len);
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rx.len = rx_len;
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rx.cs_change = 0;
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rx.delay.value = nspi->xfer_udelay;
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rx.delay.unit = SPI_DELAY_UNIT_USECS;
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rx.speed_hz = nspi->xfer_speed_hz;
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spi_message_add_tail(&rx, &m);
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ret = spi_sync(nspi->spi, &m);
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if (ret)
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goto receive_error;
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if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
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*(u8 *)skb_push(skb, 1) = resp_hdr[1];
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*(u8 *)skb_push(skb, 1) = resp_hdr[0];
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}
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return skb;
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receive_error:
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kfree_skb(skb);
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return NULL;
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}
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static int nci_spi_check_crc(struct sk_buff *skb)
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{
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u16 crc_data = (skb->data[skb->len - 2] << 8) |
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skb->data[skb->len - 1];
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int ret;
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ret = (crc_ccitt(CRC_INIT, skb->data, skb->len - NCI_SPI_CRC_LEN)
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== crc_data);
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skb_trim(skb, skb->len - NCI_SPI_CRC_LEN);
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return ret;
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}
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static u8 nci_spi_get_ack(struct sk_buff *skb)
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{
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u8 ret;
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ret = skb->data[0] >> NCI_SPI_ACK_SHIFT;
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/* Remove NFCC part of the header: ACK, NACK and MSB payload len */
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skb_pull(skb, 2);
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return ret;
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}
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/**
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* nci_spi_read - read frame from NCI SPI drivers
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*
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* @nspi: The nci spi
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* Context: can sleep
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*
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* This call may only be used from a context that may sleep. The sleep
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* is non-interruptible, and has no timeout.
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*
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* It returns an allocated skb containing the frame on success, or NULL.
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*/
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struct sk_buff *nci_spi_read(struct nci_spi *nspi)
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{
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struct sk_buff *skb;
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/* Retrieve frame from SPI */
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skb = __nci_spi_read(nspi);
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if (!skb)
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goto done;
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if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
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if (!nci_spi_check_crc(skb)) {
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send_acknowledge(nspi, ACKNOWLEDGE_NACK);
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goto done;
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}
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/* In case of acknowledged mode: if ACK or NACK received,
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* unblock completion of latest frame sent.
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*/
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nspi->req_result = nci_spi_get_ack(skb);
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if (nspi->req_result)
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complete(&nspi->req_completion);
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}
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/* If there is no payload (ACK/NACK only frame),
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* free the socket buffer
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*/
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if (!skb->len) {
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kfree_skb(skb);
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skb = NULL;
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goto done;
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}
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if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED)
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send_acknowledge(nspi, ACKNOWLEDGE_ACK);
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done:
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return skb;
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}
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EXPORT_SYMBOL_GPL(nci_spi_read);
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MODULE_LICENSE("GPL");
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