net/nfc/nci/spi.c

   1 /*
   2  * Copyright (C) 2013  Intel Corporation. All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms and conditions of the GNU General Public License,
   6  * version 2, as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  16  *
  17  */
  18
  19 #define pr_fmt(fmt) "nci_spi: %s: " fmt, __func__
  20
  21 #include <linux/export.h>
  22 #include <linux/spi/spi.h>
  23 #include <linux/crc-ccitt.h>
  24 #include <linux/nfc.h>
  25 #include <net/nfc/nci_core.h>
  26
  27 #define NCI_SPI_HDR_LEN                 4
  28 #define NCI_SPI_CRC_LEN                 2
  29
  30 #define NCI_SPI_SEND_TIMEOUT    (NCI_CMD_TIMEOUT > NCI_DATA_TIMEOUT ? \
  31                                         NCI_CMD_TIMEOUT : NCI_DATA_TIMEOUT)
  32
  33 #define NCI_SPI_DIRECT_WRITE    0x01
  34 #define NCI_SPI_DIRECT_READ     0x02
  35
  36 #define ACKNOWLEDGE_NONE        0
  37 #define ACKNOWLEDGE_ACK         1
  38 #define ACKNOWLEDGE_NACK        2
  39
  40 #define CRC_INIT                0xFFFF
  41
  42 static int nci_spi_open(struct nci_dev *nci_dev)
  43 {
  44         struct nci_spi_dev *ndev = nci_get_drvdata(nci_dev);
  45
  46         return ndev->ops->open(ndev);
  47 }
  48
  49 static int nci_spi_close(struct nci_dev *nci_dev)
  50 {
  51         struct nci_spi_dev *ndev = nci_get_drvdata(nci_dev);
  52
  53         return ndev->ops->close(ndev);
  54 }
  55
  56 static int __nci_spi_send(struct nci_spi_dev *ndev, struct sk_buff *skb)
  57 {
  58         struct spi_message m;
  59         struct spi_transfer t;
  60
  61         t.tx_buf = skb->data;
  62         t.len = skb->len;
  63         t.cs_change = 0;
  64         t.delay_usecs = ndev->xfer_udelay;
  65
  66         spi_message_init(&m);
  67         spi_message_add_tail(&t, &m);
  68
  69         return spi_sync(ndev->spi, &m);
  70 }
  71
  72 static int nci_spi_send(struct nci_dev *nci_dev, struct sk_buff *skb)
  73 {
  74         struct nci_spi_dev *ndev = nci_get_drvdata(nci_dev);
  75         unsigned int payload_len = skb->len;
  76         unsigned char *hdr;
  77         int ret;
  78         long completion_rc;
  79
  80         ndev->ops->deassert_int(ndev);
  81
  82         /* add the NCI SPI header to the start of the buffer */
  83         hdr = skb_push(skb, NCI_SPI_HDR_LEN);
  84         hdr[0] = NCI_SPI_DIRECT_WRITE;
  85         hdr[1] = ndev->acknowledge_mode;
  86         hdr[2] = payload_len >> 8;
  87         hdr[3] = payload_len & 0xFF;
  88
  89         if (ndev->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
  90                 u16 crc;
  91
  92                 crc = crc_ccitt(CRC_INIT, skb->data, skb->len);
  93                 *skb_put(skb, 1) = crc >> 8;
  94                 *skb_put(skb, 1) = crc & 0xFF;
  95         }
  96
  97         ret = __nci_spi_send(ndev, skb);
  98
  99         kfree_skb(skb);
 100         ndev->ops->assert_int(ndev);
 101
 102         if (ret != 0 || ndev->acknowledge_mode == NCI_SPI_CRC_DISABLED)
 103                 goto done;
 104
 105         init_completion(&ndev->req_completion);
 106         completion_rc =
 107                 wait_for_completion_interruptible_timeout(&ndev->req_completion,
 108                                                           NCI_SPI_SEND_TIMEOUT);
 109
 110         if (completion_rc <= 0 || ndev->req_result == ACKNOWLEDGE_NACK)
 111                 ret = -EIO;
 112
 113 done:
 114         return ret;
 115 }
 116
 117 static struct nci_ops nci_spi_ops = {
 118         .open = nci_spi_open,
 119         .close = nci_spi_close,
 120         .send = nci_spi_send,
 121 };
 122
 123 /* ---- Interface to NCI SPI drivers ---- */
 124
 125 /**
 126  * nci_spi_allocate_device - allocate a new nci spi device
 127  *
 128  * @spi: SPI device
 129  * @ops: device operations
 130  * @supported_protocols: NFC protocols supported by the device
 131  * @supported_se: NFC Secure Elements supported by the device
 132  * @acknowledge_mode: Acknowledge mode used by the device
 133  * @delay: delay between transactions in us
 134  */
 135 struct nci_spi_dev *nci_spi_allocate_device(struct spi_device *spi,
 136                                                 struct nci_spi_ops *ops,
 137                                                 u32 supported_protocols,
 138                                                 u32 supported_se,
 139                                                 u8 acknowledge_mode,
 140                                                 unsigned int delay)
 141 {
 142         struct nci_spi_dev *ndev;
 143         int tailroom = 0;
 144
 145         if (!ops->open || !ops->close || !ops->assert_int || !ops->deassert_int)
 146                 return NULL;
 147
 148         if (!supported_protocols)
 149                 return NULL;
 150
 151         ndev = devm_kzalloc(&spi->dev, sizeof(struct nci_dev), GFP_KERNEL);
 152         if (!ndev)
 153                 return NULL;
 154
 155         ndev->ops = ops;
 156         ndev->acknowledge_mode = acknowledge_mode;
 157         ndev->xfer_udelay = delay;
 158
 159         if (acknowledge_mode == NCI_SPI_CRC_ENABLED)
 160                 tailroom += NCI_SPI_CRC_LEN;
 161
 162         ndev->nci_dev = nci_allocate_device(&nci_spi_ops, supported_protocols,
 163                                             supported_se, NCI_SPI_HDR_LEN,
 164                                             tailroom);
 165         if (!ndev->nci_dev)
 166                 return NULL;
 167
 168         nci_set_drvdata(ndev->nci_dev, ndev);
 169
 170         return ndev;
 171 }
 172 EXPORT_SYMBOL_GPL(nci_spi_allocate_device);
 173
 174 /**
 175  * nci_spi_free_device - deallocate nci spi device
 176  *
 177  * @ndev: The nci spi device to deallocate
 178  */
 179 void nci_spi_free_device(struct nci_spi_dev *ndev)
 180 {
 181         nci_free_device(ndev->nci_dev);
 182 }
 183 EXPORT_SYMBOL_GPL(nci_spi_free_device);
 184
 185 /**
 186  * nci_spi_register_device - register a nci spi device in the nfc subsystem
 187  *
 188  * @pdev: The nci spi device to register
 189  */
 190 int nci_spi_register_device(struct nci_spi_dev *ndev)
 191 {
 192         return nci_register_device(ndev->nci_dev);
 193 }
 194 EXPORT_SYMBOL_GPL(nci_spi_register_device);
 195
 196 /**
 197  * nci_spi_unregister_device - unregister a nci spi device in the nfc subsystem
 198  *
 199  * @dev: The nci spi device to unregister
 200  */
 201 void nci_spi_unregister_device(struct nci_spi_dev *ndev)
 202 {
 203         nci_unregister_device(ndev->nci_dev);
 204 }
 205 EXPORT_SYMBOL_GPL(nci_spi_unregister_device);