+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Driver for NXP PN532 NFC Chip - UART transport layer
+ *
+ * Copyright (C) 2018 Lemonage Software GmbH
+ * Author: Lars Pöschel <poeschel@lemonage.de>
+ * All rights reserved.
+ */
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/nfc.h>
+#include <linux/netdevice.h>
+#include <linux/of.h>
+#include <linux/serdev.h>
+#include "pn533.h"
+
+#define PN532_UART_SKB_BUFF_LEN (PN533_CMD_DATAEXCH_DATA_MAXLEN * 2)
+
+enum send_wakeup {
+ PN532_SEND_NO_WAKEUP = 0,
+ PN532_SEND_WAKEUP,
+ PN532_SEND_LAST_WAKEUP,
+};
+
+
+struct pn532_uart_phy {
+ struct serdev_device *serdev;
+ struct sk_buff *recv_skb;
+ struct pn533 *priv;
+ /*
+ * send_wakeup variable is used to control if we need to send a wakeup
+ * request to the pn532 chip prior to our actual command. There is a
+ * little propability of a race condition. We decided to not mutex the
+ * variable as the worst that could happen is, that we send a wakeup
+ * to the chip that is already awake. This does not hurt. It is a
+ * no-op to the chip.
+ */
+ enum send_wakeup send_wakeup;
+ struct timer_list cmd_timeout;
+ struct sk_buff *cur_out_buf;
+};
+
+static int pn532_uart_send_frame(struct pn533 *dev,
+ struct sk_buff *out)
+{
+ /* wakeup sequence and dummy bytes for waiting time */
+ static const u8 wakeup[] = {
+ 0x55, 0x55, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
+ struct pn532_uart_phy *pn532 = dev->phy;
+ int err;
+
+ print_hex_dump_debug("PN532_uart TX: ", DUMP_PREFIX_NONE, 16, 1,
+ out->data, out->len, false);
+
+ pn532->cur_out_buf = out;
+ if (pn532->send_wakeup) {
+ err = serdev_device_write(pn532->serdev,
+ wakeup, sizeof(wakeup),
+ MAX_SCHEDULE_TIMEOUT);
+ if (err < 0)
+ return err;
+ }
+
+ if (pn532->send_wakeup == PN532_SEND_LAST_WAKEUP)
+ pn532->send_wakeup = PN532_SEND_NO_WAKEUP;
+
+ err = serdev_device_write(pn532->serdev, out->data, out->len,
+ MAX_SCHEDULE_TIMEOUT);
+ if (err < 0)
+ return err;
+
+ mod_timer(&pn532->cmd_timeout, HZ / 40 + jiffies);
+ return 0;
+}
+
+static int pn532_uart_send_ack(struct pn533 *dev, gfp_t flags)
+{
+ /* spec 7.1.1.3: Preamble, SoPC (2), ACK Code (2), Postamble */
+ static const u8 ack[PN533_STD_FRAME_ACK_SIZE] = {
+ 0x00, 0x00, 0xff, 0x00, 0xff, 0x00};
+ struct pn532_uart_phy *pn532 = dev->phy;
+ int err;
+
+ err = serdev_device_write(pn532->serdev, ack, sizeof(ack),
+ MAX_SCHEDULE_TIMEOUT);
+ if (err < 0)
+ return err;
+
+ return 0;
+}
+
+static void pn532_uart_abort_cmd(struct pn533 *dev, gfp_t flags)
+{
+ /* An ack will cancel the last issued command */
+ pn532_uart_send_ack(dev, flags);
+ /* schedule cmd_complete_work to finish current command execution */
+ pn533_recv_frame(dev, NULL, -ENOENT);
+}
+
+static void pn532_dev_up(struct pn533 *dev)
+{
+ struct pn532_uart_phy *pn532 = dev->phy;
+
+ serdev_device_open(pn532->serdev);
+ pn532->send_wakeup = PN532_SEND_LAST_WAKEUP;
+}
+
+static void pn532_dev_down(struct pn533 *dev)
+{
+ struct pn532_uart_phy *pn532 = dev->phy;
+
+ serdev_device_close(pn532->serdev);
+ pn532->send_wakeup = PN532_SEND_WAKEUP;
+}
+
+static struct pn533_phy_ops uart_phy_ops = {
+ .send_frame = pn532_uart_send_frame,
+ .send_ack = pn532_uart_send_ack,
+ .abort_cmd = pn532_uart_abort_cmd,
+ .dev_up = pn532_dev_up,
+ .dev_down = pn532_dev_down,
+};
+
+static void pn532_cmd_timeout(struct timer_list *t)
+{
+ struct pn532_uart_phy *dev = from_timer(dev, t, cmd_timeout);
+
+ pn532_uart_send_frame(dev->priv, dev->cur_out_buf);
+}
+
+/*
+ * scans the buffer if it contains a pn532 frame. It is not checked if the
+ * frame is really valid. This is later done with pn533_rx_frame_is_valid.
+ * This is useful for malformed or errornous transmitted frames. Adjusts the
+ * bufferposition where the frame starts, since pn533_recv_frame expects a
+ * well formed frame.
+ */
+static int pn532_uart_rx_is_frame(struct sk_buff *skb)
+{
+ struct pn533_std_frame *std;
+ struct pn533_ext_frame *ext;
+ u16 frame_len;
+ int i;
+
+ for (i = 0; i + PN533_STD_FRAME_ACK_SIZE <= skb->len; i++) {
+ std = (struct pn533_std_frame *)&skb->data[i];
+ /* search start code */
+ if (std->start_frame != cpu_to_be16(PN533_STD_FRAME_SOF))
+ continue;
+
+ /* frame type */
+ switch (std->datalen) {
+ case PN533_FRAME_DATALEN_ACK:
+ if (std->datalen_checksum == 0xff) {
+ skb_pull(skb, i);
+ return 1;
+ }
+
+ break;
+ case PN533_FRAME_DATALEN_ERROR:
+ if ((std->datalen_checksum == 0xff) &&
+ (skb->len >=
+ PN533_STD_ERROR_FRAME_SIZE)) {
+ skb_pull(skb, i);
+ return 1;
+ }
+
+ break;
+ case PN533_FRAME_DATALEN_EXTENDED:
+ ext = (struct pn533_ext_frame *)&skb->data[i];
+ frame_len = be16_to_cpu(ext->datalen);
+ if (skb->len >= frame_len +
+ sizeof(struct pn533_ext_frame) +
+ 2 /* CKS + Postamble */) {
+ skb_pull(skb, i);
+ return 1;
+ }
+
+ break;
+ default: /* normal information frame */
+ frame_len = std->datalen;
+ if (skb->len >= frame_len +
+ sizeof(struct pn533_std_frame) +
+ 2 /* CKS + Postamble */) {
+ skb_pull(skb, i);
+ return 1;
+ }
+
+ break;
+ }
+ }
+
+ return 0;
+}
+
+static int pn532_receive_buf(struct serdev_device *serdev,
+ const unsigned char *data, size_t count)
+{
+ struct pn532_uart_phy *dev = serdev_device_get_drvdata(serdev);
+ size_t i;
+
+ del_timer(&dev->cmd_timeout);
+ for (i = 0; i < count; i++) {
+ skb_put_u8(dev->recv_skb, *data++);
+ if (!pn532_uart_rx_is_frame(dev->recv_skb))
+ continue;
+
+ pn533_recv_frame(dev->priv, dev->recv_skb, 0);
+ dev->recv_skb = alloc_skb(PN532_UART_SKB_BUFF_LEN, GFP_KERNEL);
+ if (!dev->recv_skb)
+ return 0;
+ }
+
+ return i;
+}
+
+static struct serdev_device_ops pn532_serdev_ops = {
+ .receive_buf = pn532_receive_buf,
+ .write_wakeup = serdev_device_write_wakeup,
+};
+
+static const struct of_device_id pn532_uart_of_match[] = {
+ { .compatible = "nxp,pn532", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, pn532_uart_of_match);
+
+static int pn532_uart_probe(struct serdev_device *serdev)
+{
+ struct pn532_uart_phy *pn532;
+ struct pn533 *priv;
+ int err;
+
+ err = -ENOMEM;
+ pn532 = kzalloc(sizeof(*pn532), GFP_KERNEL);
+ if (!pn532)
+ goto err_exit;
+
+ pn532->recv_skb = alloc_skb(PN532_UART_SKB_BUFF_LEN, GFP_KERNEL);
+ if (!pn532->recv_skb)
+ goto err_free;
+
+ pn532->serdev = serdev;
+ serdev_device_set_drvdata(serdev, pn532);
+ serdev_device_set_client_ops(serdev, &pn532_serdev_ops);
+ err = serdev_device_open(serdev);
+ if (err) {
+ dev_err(&serdev->dev, "Unable to open device\n");
+ goto err_skb;
+ }
+
+ err = serdev_device_set_baudrate(serdev, 115200);
+ if (err != 115200) {
+ err = -EINVAL;
+ goto err_serdev;
+ }
+
+ serdev_device_set_flow_control(serdev, false);
+ pn532->send_wakeup = PN532_SEND_WAKEUP;
+ timer_setup(&pn532->cmd_timeout, pn532_cmd_timeout, 0);
+ priv = pn53x_common_init(PN533_DEVICE_PN532,
+ PN533_PROTO_REQ_ACK_RESP,
+ pn532, &uart_phy_ops, NULL,
+ &pn532->serdev->dev);
+ if (IS_ERR(priv)) {
+ err = PTR_ERR(priv);
+ goto err_serdev;
+ }
+
+ pn532->priv = priv;
+ err = pn533_finalize_setup(pn532->priv);
+ if (err)
+ goto err_clean;
+
+ serdev_device_close(serdev);
+ err = pn53x_register_nfc(priv, PN533_NO_TYPE_B_PROTOCOLS, &serdev->dev);
+ if (err) {
+ pn53x_common_clean(pn532->priv);
+ goto err_skb;
+ }
+
+ return err;
+
+err_clean:
+ pn53x_common_clean(pn532->priv);
+err_serdev:
+ serdev_device_close(serdev);
+err_skb:
+ kfree_skb(pn532->recv_skb);
+err_free:
+ kfree(pn532);
+err_exit:
+ return err;
+}
+
+static void pn532_uart_remove(struct serdev_device *serdev)
+{
+ struct pn532_uart_phy *pn532 = serdev_device_get_drvdata(serdev);
+
+ pn53x_unregister_nfc(pn532->priv);
+ serdev_device_close(serdev);
+ pn53x_common_clean(pn532->priv);
+ kfree_skb(pn532->recv_skb);
+ kfree(pn532);
+}
+
+static struct serdev_device_driver pn532_uart_driver = {
+ .probe = pn532_uart_probe,
+ .remove = pn532_uart_remove,
+ .driver = {
+ .name = "pn532_uart",
+ .of_match_table = of_match_ptr(pn532_uart_of_match),
+ },
+};
+
+module_serdev_device_driver(pn532_uart_driver);
+
+MODULE_AUTHOR("Lars Pöschel <poeschel@lemonage.de>");
+MODULE_DESCRIPTION("PN532 UART driver");
+MODULE_LICENSE("GPL");
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