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320 lines
7.1 KiB
320 lines
7.1 KiB
// 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, const 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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