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 int pn532_dev_up(struct pn533 *dev)
 104 {
 105         struct pn532_uart_phy *pn532 = dev->phy;
 106         int ret = 0;
 107
 108         ret = serdev_device_open(pn532->serdev);
 109         if (ret)
 110                 return ret;
 111
 112         pn532->send_wakeup = PN532_SEND_LAST_WAKEUP;
 113         return ret;
 114 }
 115
 116 static int pn532_dev_down(struct pn533 *dev)
 117 {
 118         struct pn532_uart_phy *pn532 = dev->phy;
 119
 120         serdev_device_close(pn532->serdev);
 121         pn532->send_wakeup = PN532_SEND_WAKEUP;
 122
 123         return 0;
 124 }
 125
 126 static const struct pn533_phy_ops uart_phy_ops = {
 127         .send_frame = pn532_uart_send_frame,
 128         .send_ack = pn532_uart_send_ack,
 129         .abort_cmd = pn532_uart_abort_cmd,
 130         .dev_up = pn532_dev_up,
 131         .dev_down = pn532_dev_down,
 132 };
 133
 134 static void pn532_cmd_timeout(struct timer_list *t)
 135 {
 136         struct pn532_uart_phy *dev = from_timer(dev, t, cmd_timeout);
 137
 138         pn532_uart_send_frame(dev->priv, dev->cur_out_buf);
 139 }
 140
 141 /*
 142  * scans the buffer if it contains a pn532 frame. It is not checked if the
 143  * frame is really valid. This is later done with pn533_rx_frame_is_valid.
 144  * This is useful for malformed or errornous transmitted frames. Adjusts the
 145  * bufferposition where the frame starts, since pn533_recv_frame expects a
 146  * well formed frame.
 147  */
 148 static int pn532_uart_rx_is_frame(struct sk_buff *skb)
 149 {
 150         struct pn533_std_frame *std;
 151         struct pn533_ext_frame *ext;
 152         u16 frame_len;
 153         int i;
 154
 155         for (i = 0; i + PN533_STD_FRAME_ACK_SIZE <= skb->len; i++) {
 156                 std = (struct pn533_std_frame *)&skb->data[i];
 157                 /* search start code */
 158                 if (std->start_frame != cpu_to_be16(PN533_STD_FRAME_SOF))
 159                         continue;
 160
 161                 /* frame type */
 162                 switch (std->datalen) {
 163                 case PN533_FRAME_DATALEN_ACK:
 164                         if (std->datalen_checksum == 0xff) {
 165                                 skb_pull(skb, i);
 166                                 return 1;
 167                         }
 168
 169                         break;
 170                 case PN533_FRAME_DATALEN_ERROR:
 171                         if ((std->datalen_checksum == 0xff) &&
 172                                         (skb->len >=
 173                                          PN533_STD_ERROR_FRAME_SIZE)) {
 174                                 skb_pull(skb, i);
 175                                 return 1;
 176                         }
 177
 178                         break;
 179                 case PN533_FRAME_DATALEN_EXTENDED:
 180                         ext = (struct pn533_ext_frame *)&skb->data[i];
 181                         frame_len = be16_to_cpu(ext->datalen);
 182                         if (skb->len >= frame_len +
 183                                         sizeof(struct pn533_ext_frame) +
 184                                         2 /* CKS + Postamble */) {
 185                                 skb_pull(skb, i);
 186                                 return 1;
 187                         }
 188
 189                         break;
 190                 default: /* normal information frame */
 191                         frame_len = std->datalen;
 192                         if (skb->len >= frame_len +
 193                                         sizeof(struct pn533_std_frame) +
 194                                         2 /* CKS + Postamble */) {
 195                                 skb_pull(skb, i);
 196                                 return 1;
 197                         }
 198
 199                         break;
 200                 }
 201         }
 202
 203         return 0;
 204 }
 205
 206 static int pn532_receive_buf(struct serdev_device *serdev,
 207                 const unsigned char *data, size_t count)
 208 {
 209         struct pn532_uart_phy *dev = serdev_device_get_drvdata(serdev);
 210         size_t i;
 211
 212         del_timer(&dev->cmd_timeout);
 213         for (i = 0; i < count; i++) {
 214                 skb_put_u8(dev->recv_skb, *data++);
 215                 if (!pn532_uart_rx_is_frame(dev->recv_skb))
 216                         continue;
 217
 218                 pn533_recv_frame(dev->priv, dev->recv_skb, 0);
 219                 dev->recv_skb = alloc_skb(PN532_UART_SKB_BUFF_LEN, GFP_KERNEL);
 220                 if (!dev->recv_skb)
 221                         return 0;
 222         }
 223
 224         return i;
 225 }
 226
 227 static const struct serdev_device_ops pn532_serdev_ops = {
 228         .receive_buf = pn532_receive_buf,
 229         .write_wakeup = serdev_device_write_wakeup,
 230 };
 231
 232 static const struct of_device_id pn532_uart_of_match[] = {
 233         { .compatible = "nxp,pn532", },
 234         {},
 235 };
 236 MODULE_DEVICE_TABLE(of, pn532_uart_of_match);
 237
 238 static int pn532_uart_probe(struct serdev_device *serdev)
 239 {
 240         struct pn532_uart_phy *pn532;
 241         struct pn533 *priv;
 242         int err;
 243
 244         err = -ENOMEM;
 245         pn532 = kzalloc(sizeof(*pn532), GFP_KERNEL);
 246         if (!pn532)
 247                 goto err_exit;
 248
 249         pn532->recv_skb = alloc_skb(PN532_UART_SKB_BUFF_LEN, GFP_KERNEL);
 250         if (!pn532->recv_skb)
 251                 goto err_free;
 252
 253         pn532->serdev = serdev;
 254         serdev_device_set_drvdata(serdev, pn532);
 255         serdev_device_set_client_ops(serdev, &pn532_serdev_ops);
 256         err = serdev_device_open(serdev);
 257         if (err) {
 258                 dev_err(&serdev->dev, "Unable to open device\n");
 259                 goto err_skb;
 260         }
 261
 262         err = serdev_device_set_baudrate(serdev, 115200);
 263         if (err != 115200) {
 264                 err = -EINVAL;
 265                 goto err_serdev;
 266         }
 267
 268         serdev_device_set_flow_control(serdev, false);
 269         pn532->send_wakeup = PN532_SEND_WAKEUP;
 270         timer_setup(&pn532->cmd_timeout, pn532_cmd_timeout, 0);
 271         priv = pn53x_common_init(PN533_DEVICE_PN532_AUTOPOLL,
 272                                      PN533_PROTO_REQ_ACK_RESP,
 273                                      pn532, &uart_phy_ops, NULL,
 274                                      &pn532->serdev->dev);
 275         if (IS_ERR(priv)) {
 276                 err = PTR_ERR(priv);
 277                 goto err_serdev;
 278         }
 279
 280         pn532->priv = priv;
 281         err = pn533_finalize_setup(pn532->priv);
 282         if (err)
 283                 goto err_clean;
 284
 285         serdev_device_close(serdev);
 286         err = pn53x_register_nfc(priv, PN533_NO_TYPE_B_PROTOCOLS, &serdev->dev);
 287         if (err) {
 288                 pn53x_common_clean(pn532->priv);
 289                 goto err_skb;
 290         }
 291
 292         return err;
 293
 294 err_clean:
 295         pn53x_common_clean(pn532->priv);
 296 err_serdev:
 297         serdev_device_close(serdev);
 298 err_skb:
 299         kfree_skb(pn532->recv_skb);
 300 err_free:
 301         kfree(pn532);
 302 err_exit:
 303         return err;
 304 }
 305
 306 static void pn532_uart_remove(struct serdev_device *serdev)
 307 {
 308         struct pn532_uart_phy *pn532 = serdev_device_get_drvdata(serdev);
 309
 310         pn53x_unregister_nfc(pn532->priv);
 311         serdev_device_close(serdev);
 312         pn53x_common_clean(pn532->priv);
 313         del_timer_sync(&pn532->cmd_timeout);
 314         kfree_skb(pn532->recv_skb);
 315         kfree(pn532);
 316 }
 317
 318 static struct serdev_device_driver pn532_uart_driver = {
 319         .probe = pn532_uart_probe,
 320         .remove = pn532_uart_remove,
 321         .driver = {
 322                 .name = "pn532_uart",
 323                 .of_match_table = pn532_uart_of_match,
 324         },
 325 };
 326
 327 module_serdev_device_driver(pn532_uart_driver);
 328
 329 MODULE_AUTHOR("Lars Pöschel <poeschel@lemonage.de>");
 330 MODULE_DESCRIPTION("PN532 UART driver");
 331 MODULE_LICENSE("GPL");