// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *
 *  Bluetooth HCI UART driver
 *
 *  Copyright (C) 2000-2001  Qualcomm Incorporated
 *  Copyright (C) 2002-2003  Maxim Krasnyansky <maxk@qualcomm.com>
 *  Copyright (C) 2004-2005  Marcel Holtmann <marcel@holtmann.org>
 */

#include <linux/module.h>

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/interrupt.h>
#include <linux/ptrace.h>
#include <linux/poll.h>

#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/signal.h>
#include <linux/ioctl.h>
#include <linux/skbuff.h>
#include <linux/unaligned.h>

#include <net/bluetooth/bluetooth.h>
#include <net/bluetooth/hci_core.h>

#include "hci_uart.h"

struct h4_struct {
        struct sk_buff *rx_skb;
        struct sk_buff_head txq;
};

/* Initialize protocol */
static int h4_open(struct hci_uart *hu)
{
        struct h4_struct *h4;

        BT_DBG("hu %p", hu);

        h4 = kzalloc_obj(*h4);
        if (!h4)
                return -ENOMEM;

        skb_queue_head_init(&h4->txq);

        hu->priv = h4;
        return 0;
}

/* Flush protocol data */
static int h4_flush(struct hci_uart *hu)
{
        struct h4_struct *h4 = hu->priv;

        BT_DBG("hu %p", hu);

        skb_queue_purge(&h4->txq);

        return 0;
}

/* Close protocol */
static int h4_close(struct hci_uart *hu)
{
        struct h4_struct *h4 = hu->priv;

        BT_DBG("hu %p", hu);

        skb_queue_purge(&h4->txq);

        kfree_skb(h4->rx_skb);

        hu->priv = NULL;
        kfree(h4);

        return 0;
}

/* Enqueue frame for transmission (padding, crc, etc) */
static int h4_enqueue(struct hci_uart *hu, struct sk_buff *skb)
{
        struct h4_struct *h4 = hu->priv;

        BT_DBG("hu %p skb %p", hu, skb);

        /* Prepend skb with frame type */
        memcpy(skb_push(skb, 1), &hci_skb_pkt_type(skb), 1);
        skb_queue_tail(&h4->txq, skb);

        return 0;
}

static const struct h4_recv_pkt h4_recv_pkts[] = {
        { H4_RECV_ACL,   .recv = hci_recv_frame },
        { H4_RECV_SCO,   .recv = hci_recv_frame },
        { H4_RECV_EVENT, .recv = hci_recv_frame },
        { H4_RECV_ISO,   .recv = hci_recv_frame },
};

/* Recv data */
static int h4_recv(struct hci_uart *hu, const void *data, int count)
{
        struct h4_struct *h4 = hu->priv;

        h4->rx_skb = h4_recv_buf(hu, h4->rx_skb, data, count,
                                 h4_recv_pkts, ARRAY_SIZE(h4_recv_pkts));
        if (IS_ERR(h4->rx_skb)) {
                int err = PTR_ERR(h4->rx_skb);
                bt_dev_err(hu->hdev, "Frame reassembly failed (%d)", err);
                h4->rx_skb = NULL;
                return err;
        }

        return count;
}

static struct sk_buff *h4_dequeue(struct hci_uart *hu)
{
        struct h4_struct *h4 = hu->priv;
        return skb_dequeue(&h4->txq);
}

static const struct hci_uart_proto h4p = {
        .id             = HCI_UART_H4,
        .name           = "H4",
        .open           = h4_open,
        .close          = h4_close,
        .recv           = h4_recv,
        .enqueue        = h4_enqueue,
        .dequeue        = h4_dequeue,
        .flush          = h4_flush,
};

int __init h4_init(void)
{
        return hci_uart_register_proto(&h4p);
}

int __exit h4_deinit(void)
{
        return hci_uart_unregister_proto(&h4p);
}

struct sk_buff *h4_recv_buf(struct hci_uart *hu, struct sk_buff *skb,
                            const unsigned char *buffer, int count,
                            const struct h4_recv_pkt *pkts, int pkts_count)
{
        u8 alignment = hu->alignment ? hu->alignment : 1;
        struct hci_dev *hdev = hu->hdev;

        /* Check for error from previous call */
        if (IS_ERR(skb))
                skb = NULL;

        while (count) {
                int i, len;

                /* remove padding bytes from buffer */
                for (; hu->padding && count > 0; hu->padding--) {
                        count--;
                        buffer++;
                }
                if (!count)
                        break;

                if (!skb) {
                        for (i = 0; i < pkts_count; i++) {
                                if (buffer[0] != (&pkts[i])->type)
                                        continue;

                                skb = bt_skb_alloc((&pkts[i])->maxlen,
                                                   GFP_ATOMIC);
                                if (!skb)
                                        return ERR_PTR(-ENOMEM);

                                hci_skb_pkt_type(skb) = (&pkts[i])->type;
                                hci_skb_expect(skb) = (&pkts[i])->hlen;
                                break;
                        }

                        /* Check for invalid packet type */
                        if (!skb)
                                return ERR_PTR(-EILSEQ);

                        count -= 1;
                        buffer += 1;
                }

                len = min_t(uint, hci_skb_expect(skb) - skb->len, count);
                skb_put_data(skb, buffer, len);

                count -= len;
                buffer += len;

                /* Check for partial packet */
                if (skb->len < hci_skb_expect(skb))
                        continue;

                for (i = 0; i < pkts_count; i++) {
                        if (hci_skb_pkt_type(skb) == (&pkts[i])->type)
                                break;
                }

                if (i >= pkts_count) {
                        kfree_skb(skb);
                        return ERR_PTR(-EILSEQ);
                }

                if (skb->len == (&pkts[i])->hlen) {
                        u16 dlen;

                        switch ((&pkts[i])->lsize) {
                        case 0:
                                /* No variable data length */
                                dlen = 0;
                                break;
                        case 1:
                                /* Single octet variable length */
                                dlen = skb->data[(&pkts[i])->loff];
                                hci_skb_expect(skb) += dlen;

                                if (skb_tailroom(skb) < dlen) {
                                        kfree_skb(skb);
                                        return ERR_PTR(-EMSGSIZE);
                                }
                                break;
                        case 2:
                                /* Double octet variable length */
                                dlen = get_unaligned_le16(skb->data +
                                                          (&pkts[i])->loff);
                                hci_skb_expect(skb) += dlen;

                                if (skb_tailroom(skb) < dlen) {
                                        kfree_skb(skb);
                                        return ERR_PTR(-EMSGSIZE);
                                }
                                break;
                        default:
                                /* Unsupported variable length */
                                kfree_skb(skb);
                                return ERR_PTR(-EILSEQ);
                        }

                        if (!dlen) {
                                hu->padding = (skb->len + 1) % alignment;
                                hu->padding = (alignment - hu->padding) % alignment;

                                /* No more data, complete frame */
                                (&pkts[i])->recv(hdev, skb);
                                skb = NULL;
                        }
                } else {
                        hu->padding = (skb->len + 1) % alignment;
                        hu->padding = (alignment - hu->padding) % alignment;

                        /* Complete frame */
                        (&pkts[i])->recv(hdev, skb);
                        skb = NULL;
                }
        }

        return skb;
}
EXPORT_SYMBOL_GPL(h4_recv_buf);