linux/drivers/nfc/pn533/uart.c
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   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 P\xC3\xB6schel <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
  21enum send_wakeup {
  22        PN532_SEND_NO_WAKEUP = 0,
  23        PN532_SEND_WAKEUP,
  24        PN532_SEND_LAST_WAKEUP,
  25};
  26
  27
  28struct 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
  45static 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
  79static 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
  95static 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
 103static 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
 116static 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
 126static 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
 134static 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 */
 148static 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
 206static 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
 227static struct serdev_device_ops pn532_serdev_ops = {
 228        .receive_buf = pn532_receive_buf,
 229        .write_wakeup = serdev_device_write_wakeup,
 230};
 231
 232static const struct of_device_id pn532_uart_of_match[] = {
 233        { .compatible = "nxp,pn532", },
 234        {},
 235};
 236MODULE_DEVICE_TABLE(of, pn532_uart_of_match);
 237
 238static 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
 294err_clean:
 295        pn53x_common_clean(pn532->priv);
 296err_serdev:
 297        serdev_device_close(serdev);
 298err_skb:
 299        kfree_skb(pn532->recv_skb);
 300err_free:
 301        kfree(pn532);
 302err_exit:
 303        return err;
 304}
 305
 306static 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        kfree_skb(pn532->recv_skb);
 314        kfree(pn532);
 315}
 316
 317static struct serdev_device_driver pn532_uart_driver = {
 318        .probe = pn532_uart_probe,
 319        .remove = pn532_uart_remove,
 320        .driver = {
 321                .name = "pn532_uart",
 322                .of_match_table = of_match_ptr(pn532_uart_of_match),
 323        },
 324};
 325
 326module_serdev_device_driver(pn532_uart_driver);
 327
 328MODULE_AUTHOR("Lars P\xC3\xB6schel <poeschel@lemonage.de>");
 329MODULE_DESCRIPTION("PN532 UART driver");
 330MODULE_LICENSE("GPL");
 331