drivers/nfc/pn533/uart.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Driver for NXP PN532 NFC Chip - UART transport layer
   4  *
   5  * Copyright (C) 2018 Lemonage Software GmbH
   6  * Author: Lars Pöschel <poeschel@lemonage.de>
   7  * All rights reserved.
   8  */
   9
  10 #include <linux/device.h>
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/nfc.h>
  14 #include <linux/netdevice.h>
  15 #include <linux/of.h>
  16 #include <linux/serdev.h>
  17 #include "pn533.h"
  18
  19 #define PN532_UART_SKB_BUFF_LEN (PN533_CMD_DATAEXCH_DATA_MAXLEN * 2)
  20
  21 enum send_wakeup {
  22         PN532_SEND_NO_WAKEUP = 0,
  23         PN532_SEND_WAKEUP,
  24         PN532_SEND_LAST_WAKEUP,
  25 };
  26
  27
  28 struct pn532_uart_phy {
  29         struct serdev_device *serdev;
  30         struct sk_buff *recv_skb;
  31         struct pn533 *priv;
  32         /*
  33          * send_wakeup variable is used to control if we need to send a wakeup
  34          * request to the pn532 chip prior to our actual command. There is a
  35          * little propability of a race condition. We decided to not mutex the
  36          * variable as the worst that could happen is, that we send a wakeup
  37          * to the chip that is already awake. This does not hurt. It is a
  38          * no-op to the chip.
  39          */
  40         enum send_wakeup send_wakeup;
  41         struct timer_list cmd_timeout;
  42         struct sk_buff *cur_out_buf;
  43 };
  44
  45 static int pn532_uart_send_frame(struct pn533 *dev,
  46                                 struct sk_buff *out)
  47 {
  48         /* wakeup sequence and dummy bytes for waiting time */
  49         static const u8 wakeup[] = {
  50                 0x55, 0x55, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  51                 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
  52         struct pn532_uart_phy *pn532 = dev->phy;
  53         int err;
  54
  55         print_hex_dump_debug("PN532_uart TX: ", DUMP_PREFIX_NONE, 16, 1,
  56                              out->data, out->len, false);
  57
  58         pn532->cur_out_buf = out;
  59         if (pn532->send_wakeup) {
  60                 err = serdev_device_write(pn532->serdev,
  61                                 wakeup, sizeof(wakeup),
  62                                 MAX_SCHEDULE_TIMEOUT);
  63                 if (err < 0)
  64                         return err;
  65         }
  66
  67         if (pn532->send_wakeup == PN532_SEND_LAST_WAKEUP)
  68                 pn532->send_wakeup = PN532_SEND_NO_WAKEUP;
  69
  70         err = serdev_device_write(pn532->serdev, out->data, out->len,
  71                         MAX_SCHEDULE_TIMEOUT);
  72         if (err < 0)
  73                 return err;
  74
  75         mod_timer(&pn532->cmd_timeout, HZ / 40 + jiffies);
  76         return 0;
  77 }
  78
  79 static int pn532_uart_send_ack(struct pn533 *dev, gfp_t flags)
  80 {
  81         /* spec 7.1.1.3:  Preamble, SoPC (2), ACK Code (2), Postamble */
  82         static const u8 ack[PN533_STD_FRAME_ACK_SIZE] = {
  83                         0x00, 0x00, 0xff, 0x00, 0xff, 0x00};
  84         struct pn532_uart_phy *pn532 = dev->phy;
  85         int err;
  86
  87         err = serdev_device_write(pn532->serdev, ack, sizeof(ack),
  88                         MAX_SCHEDULE_TIMEOUT);
  89         if (err < 0)
  90                 return err;
  91
  92         return 0;
  93 }
  94
  95 static void pn532_uart_abort_cmd(struct pn533 *dev, gfp_t flags)
  96 {
  97         /* An ack will cancel the last issued command */
  98         pn532_uart_send_ack(dev, flags);
  99         /* schedule cmd_complete_work to finish current command execution */
 100         pn533_recv_frame(dev, NULL, -ENOENT);
 101 }
 102
 103 static void pn532_dev_up(struct pn533 *dev)
 104 {
 105         struct pn532_uart_phy *pn532 = dev->phy;
 106
 107         serdev_device_open(pn532->serdev);
 108         pn532->send_wakeup = PN532_SEND_LAST_WAKEUP;
 109 }
 110
 111 static void pn532_dev_down(struct pn533 *dev)
 112 {
 113         struct pn532_uart_phy *pn532 = dev->phy;
 114
 115         serdev_device_close(pn532->serdev);
 116         pn532->send_wakeup = PN532_SEND_WAKEUP;
 117 }
 118
 119 static struct pn533_phy_ops uart_phy_ops = {
 120         .send_frame = pn532_uart_send_frame,
 121         .send_ack = pn532_uart_send_ack,
 122         .abort_cmd = pn532_uart_abort_cmd,
 123         .dev_up = pn532_dev_up,
 124         .dev_down = pn532_dev_down,
 125 };
 126
 127 static void pn532_cmd_timeout(struct timer_list *t)
 128 {
 129         struct pn532_uart_phy *dev = from_timer(dev, t, cmd_timeout);
 130
 131         pn532_uart_send_frame(dev->priv, dev->cur_out_buf);
 132 }
 133
 134 /*
 135  * scans the buffer if it contains a pn532 frame. It is not checked if the
 136  * frame is really valid. This is later done with pn533_rx_frame_is_valid.
 137  * This is useful for malformed or errornous transmitted frames. Adjusts the
 138  * bufferposition where the frame starts, since pn533_recv_frame expects a
 139  * well formed frame.
 140  */
 141 static int pn532_uart_rx_is_frame(struct sk_buff *skb)
 142 {
 143         struct pn533_std_frame *std;
 144         struct pn533_ext_frame *ext;
 145         u16 frame_len;
 146         int i;
 147
 148         for (i = 0; i + PN533_STD_FRAME_ACK_SIZE <= skb->len; i++) {
 149                 std = (struct pn533_std_frame *)&skb->data[i];
 150                 /* search start code */
 151                 if (std->start_frame != cpu_to_be16(PN533_STD_FRAME_SOF))
 152                         continue;
 153
 154                 /* frame type */
 155                 switch (std->datalen) {
 156                 case PN533_FRAME_DATALEN_ACK:
 157                         if (std->datalen_checksum == 0xff) {
 158                                 skb_pull(skb, i);
 159                                 return 1;
 160                         }
 161
 162                         break;
 163                 case PN533_FRAME_DATALEN_ERROR:
 164                         if ((std->datalen_checksum == 0xff) &&
 165                                         (skb->len >=
 166                                          PN533_STD_ERROR_FRAME_SIZE)) {
 167                                 skb_pull(skb, i);
 168                                 return 1;
 169                         }
 170
 171                         break;
 172                 case PN533_FRAME_DATALEN_EXTENDED:
 173                         ext = (struct pn533_ext_frame *)&skb->data[i];
 174                         frame_len = be16_to_cpu(ext->datalen);
 175                         if (skb->len >= frame_len +
 176                                         sizeof(struct pn533_ext_frame) +
 177                                         2 /* CKS + Postamble */) {
 178                                 skb_pull(skb, i);
 179                                 return 1;
 180                         }
 181
 182                         break;
 183                 default: /* normal information frame */
 184                         frame_len = std->datalen;
 185                         if (skb->len >= frame_len +
 186                                         sizeof(struct pn533_std_frame) +
 187                                         2 /* CKS + Postamble */) {
 188                                 skb_pull(skb, i);
 189                                 return 1;
 190                         }
 191
 192                         break;
 193                 }
 194         }
 195
 196         return 0;
 197 }
 198
 199 static int pn532_receive_buf(struct serdev_device *serdev,
 200                 const unsigned char *data, size_t count)
 201 {
 202         struct pn532_uart_phy *dev = serdev_device_get_drvdata(serdev);
 203         size_t i;
 204
 205         del_timer(&dev->cmd_timeout);
 206         for (i = 0; i < count; i++) {
 207                 skb_put_u8(dev->recv_skb, *data++);
 208                 if (!pn532_uart_rx_is_frame(dev->recv_skb))
 209                         continue;
 210
 211                 pn533_recv_frame(dev->priv, dev->recv_skb, 0);
 212                 dev->recv_skb = alloc_skb(PN532_UART_SKB_BUFF_LEN, GFP_KERNEL);
 213                 if (!dev->recv_skb)
 214                         return 0;
 215         }
 216
 217         return i;
 218 }
 219
 220 static struct serdev_device_ops pn532_serdev_ops = {
 221         .receive_buf = pn532_receive_buf,
 222         .write_wakeup = serdev_device_write_wakeup,
 223 };
 224
 225 static const struct of_device_id pn532_uart_of_match[] = {
 226         { .compatible = "nxp,pn532", },
 227         {},
 228 };
 229 MODULE_DEVICE_TABLE(of, pn532_uart_of_match);
 230
 231 static int pn532_uart_probe(struct serdev_device *serdev)
 232 {
 233         struct pn532_uart_phy *pn532;
 234         struct pn533 *priv;
 235         int err;
 236
 237         err = -ENOMEM;
 238         pn532 = kzalloc(sizeof(*pn532), GFP_KERNEL);
 239         if (!pn532)
 240                 goto err_exit;
 241
 242         pn532->recv_skb = alloc_skb(PN532_UART_SKB_BUFF_LEN, GFP_KERNEL);
 243         if (!pn532->recv_skb)
 244                 goto err_free;
 245
 246         pn532->serdev = serdev;
 247         serdev_device_set_drvdata(serdev, pn532);
 248         serdev_device_set_client_ops(serdev, &pn532_serdev_ops);
 249         err = serdev_device_open(serdev);
 250         if (err) {
 251                 dev_err(&serdev->dev, "Unable to open device\n");
 252                 goto err_skb;
 253         }
 254
 255         err = serdev_device_set_baudrate(serdev, 115200);
 256         if (err != 115200) {
 257                 err = -EINVAL;
 258                 goto err_serdev;
 259         }
 260
 261         serdev_device_set_flow_control(serdev, false);
 262         pn532->send_wakeup = PN532_SEND_WAKEUP;
 263         timer_setup(&pn532->cmd_timeout, pn532_cmd_timeout, 0);
 264         priv = pn53x_common_init(PN533_DEVICE_PN532_AUTOPOLL,
 265                                      PN533_PROTO_REQ_ACK_RESP,
 266                                      pn532, &uart_phy_ops, NULL,
 267                                      &pn532->serdev->dev);
 268         if (IS_ERR(priv)) {
 269                 err = PTR_ERR(priv);
 270                 goto err_serdev;
 271         }
 272
 273         pn532->priv = priv;
 274         err = pn533_finalize_setup(pn532->priv);
 275         if (err)
 276                 goto err_clean;
 277
 278         serdev_device_close(serdev);
 279         err = pn53x_register_nfc(priv, PN533_NO_TYPE_B_PROTOCOLS, &serdev->dev);
 280         if (err) {
 281                 pn53x_common_clean(pn532->priv);
 282                 goto err_skb;
 283         }
 284
 285         return err;
 286
 287 err_clean:
 288         pn53x_common_clean(pn532->priv);
 289 err_serdev:
 290         serdev_device_close(serdev);
 291 err_skb:
 292         kfree_skb(pn532->recv_skb);
 293 err_free:
 294         kfree(pn532);
 295 err_exit:
 296         return err;
 297 }
 298
 299 static void pn532_uart_remove(struct serdev_device *serdev)
 300 {
 301         struct pn532_uart_phy *pn532 = serdev_device_get_drvdata(serdev);
 302
 303         pn53x_unregister_nfc(pn532->priv);
 304         serdev_device_close(serdev);
 305         pn53x_common_clean(pn532->priv);
 306         kfree_skb(pn532->recv_skb);
 307         kfree(pn532);
 308 }
 309
 310 static struct serdev_device_driver pn532_uart_driver = {
 311         .probe = pn532_uart_probe,
 312         .remove = pn532_uart_remove,
 313         .driver = {
 314                 .name = "pn532_uart",
 315                 .of_match_table = of_match_ptr(pn532_uart_of_match),
 316         },
 317 };
 318
 319 module_serdev_device_driver(pn532_uart_driver);
 320
 321 MODULE_AUTHOR("Lars Pöschel <poeschel@lemonage.de>");
 322 MODULE_DESCRIPTION("PN532 UART driver");
 323 MODULE_LICENSE("GPL");