| /* |
| * 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 <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_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_open(struct nci_dev *nci_dev) |
| { |
| struct nci_spi_dev *ndev = nci_get_drvdata(nci_dev); |
| |
| return ndev->ops->open(ndev); |
| } |
| |
| static int nci_spi_close(struct nci_dev *nci_dev) |
| { |
| struct nci_spi_dev *ndev = nci_get_drvdata(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) |
| { |
| 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 = { |
| .open = nci_spi_open, |
| .close = nci_spi_close, |
| .send = nci_spi_send, |
| }; |
| |
| /* ---- Interface to NCI SPI drivers ---- */ |
| |
| /** |
| * nci_spi_allocate_device - allocate a new nci spi device |
| * |
| * @spi: SPI device |
| * @ops: device operations |
| * @supported_protocols: NFC protocols supported by the device |
| * @supported_se: NFC Secure Elements supported by the device |
| * @acknowledge_mode: Acknowledge mode used by the device |
| * @delay: delay between transactions in us |
| */ |
| struct nci_spi_dev *nci_spi_allocate_device(struct spi_device *spi, |
| struct nci_spi_ops *ops, |
| u32 supported_protocols, |
| u32 supported_se, |
| u8 acknowledge_mode, |
| unsigned int delay) |
| { |
| struct nci_spi_dev *ndev; |
| int tailroom = 0; |
| |
| if (!ops->open || !ops->close || !ops->assert_int || !ops->deassert_int) |
| return NULL; |
| |
| if (!supported_protocols) |
| return NULL; |
| |
| ndev = devm_kzalloc(&spi->dev, sizeof(struct nci_dev), GFP_KERNEL); |
| if (!ndev) |
| return NULL; |
| |
| ndev->ops = ops; |
| ndev->acknowledge_mode = acknowledge_mode; |
| ndev->xfer_udelay = delay; |
| |
| if (acknowledge_mode == NCI_SPI_CRC_ENABLED) |
| tailroom += NCI_SPI_CRC_LEN; |
| |
| ndev->nci_dev = nci_allocate_device(&nci_spi_ops, supported_protocols, |
| NCI_SPI_HDR_LEN, tailroom); |
| if (!ndev->nci_dev) |
| return NULL; |
| |
| nci_set_drvdata(ndev->nci_dev, ndev); |
| |
| return ndev; |
| } |
| EXPORT_SYMBOL_GPL(nci_spi_allocate_device); |
| |
| /** |
| * nci_spi_free_device - deallocate nci spi device |
| * |
| * @ndev: The nci spi device to deallocate |
| */ |
| void nci_spi_free_device(struct nci_spi_dev *ndev) |
| { |
| nci_free_device(ndev->nci_dev); |
| } |
| EXPORT_SYMBOL_GPL(nci_spi_free_device); |
| |
| /** |
| * nci_spi_register_device - register a nci spi device in the nfc subsystem |
| * |
| * @pdev: The nci spi device to register |
| */ |
| int nci_spi_register_device(struct nci_spi_dev *ndev) |
| { |
| return nci_register_device(ndev->nci_dev); |
| } |
| EXPORT_SYMBOL_GPL(nci_spi_register_device); |
| |
| /** |
| * nci_spi_unregister_device - unregister a nci spi device in the nfc subsystem |
| * |
| * @dev: The nci spi device to unregister |
| */ |
| 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); |