// 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 int pn532_dev_up(struct pn533 *dev)
{
        struct pn532_uart_phy *pn532 = dev->phy;
        int ret = 0;

        ret = serdev_device_open(pn532->serdev);
        if (ret)
                return ret;

        pn532->send_wakeup = PN532_SEND_LAST_WAKEUP;
        return ret;
}

static int pn532_dev_down(struct pn533 *dev)
{
        struct pn532_uart_phy *pn532 = dev->phy;

        serdev_device_close(pn532->serdev);
        pn532->send_wakeup = PN532_SEND_WAKEUP;

        return 0;
}

static const 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 = timer_container_of(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 size_t pn532_receive_buf(struct serdev_device *serdev,
                                const u8 *data, size_t count)
{
        struct pn532_uart_phy *dev = serdev_device_get_drvdata(serdev);
        size_t i;

        timer_delete(&dev->cmd_timeout);
        for (i = 0; i < count; i++) {
                if (unlikely(!skb_tailroom(dev->recv_skb)))
                        skb_trim(dev->recv_skb, 0);

                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 const 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_obj(*pn532);
        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_AUTOPOLL,
                                     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);
        timer_shutdown_sync(&pn532->cmd_timeout);
        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 = 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");