/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
/*
 *   Copyright (c) 2011, 2012, Atheros Communications Inc.
 *   Copyright (c) 2014, I2SE GmbH
 */

/*   Atheros Ethernet framing. Every Ethernet frame is surrounded by an atheros
 *   frame while transmitted over a serial channel.
 */

#ifndef _QCA_FRAMING_H
#define _QCA_FRAMING_H

#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include <linux/types.h>

/* Frame is currently being received */
#define QCAFRM_GATHER 0

/*  No header byte while expecting it */
#define QCAFRM_NOHEAD (QCAFRM_ERR_BASE - 1)

/* No tailer byte while expecting it */
#define QCAFRM_NOTAIL (QCAFRM_ERR_BASE - 2)

/* Frame length is invalid */
#define QCAFRM_INVLEN (QCAFRM_ERR_BASE - 3)

/* Frame length is invalid */
#define QCAFRM_INVFRAME (QCAFRM_ERR_BASE - 4)

/* Min/Max Ethernet MTU: 46/1500 */
#define QCAFRM_MIN_MTU (ETH_ZLEN - ETH_HLEN)
#define QCAFRM_MAX_MTU ETH_DATA_LEN

/* Min/Max frame lengths */
#define QCAFRM_MIN_LEN (QCAFRM_MIN_MTU + ETH_HLEN)
#define QCAFRM_MAX_LEN (QCAFRM_MAX_MTU + VLAN_ETH_HLEN)

/* QCA7K header len */
#define QCAFRM_HEADER_LEN 8

/* QCA7K footer len */
#define QCAFRM_FOOTER_LEN 2

/* QCA7K Framing. */
#define QCAFRM_ERR_BASE -1000

enum qcafrm_state {
        /* HW length is only available on SPI */
        QCAFRM_HW_LEN0 = 0x8000,
        QCAFRM_HW_LEN1 = QCAFRM_HW_LEN0 - 1,
        QCAFRM_HW_LEN2 = QCAFRM_HW_LEN1 - 1,
        QCAFRM_HW_LEN3 = QCAFRM_HW_LEN2 - 1,

        /*  Waiting first 0xAA of header */
        QCAFRM_WAIT_AA1 = QCAFRM_HW_LEN3 - 1,

        /*  Waiting second 0xAA of header */
        QCAFRM_WAIT_AA2 = QCAFRM_WAIT_AA1 - 1,

        /*  Waiting third 0xAA of header */
        QCAFRM_WAIT_AA3 = QCAFRM_WAIT_AA2 - 1,

        /*  Waiting fourth 0xAA of header */
        QCAFRM_WAIT_AA4 = QCAFRM_WAIT_AA3 - 1,

        /*  Waiting Byte 0-1 of length (litte endian) */
        QCAFRM_WAIT_LEN_BYTE0 = QCAFRM_WAIT_AA4 - 1,
        QCAFRM_WAIT_LEN_BYTE1 = QCAFRM_WAIT_AA4 - 2,

        /* Reserved bytes */
        QCAFRM_WAIT_RSVD_BYTE1 = QCAFRM_WAIT_AA4 - 3,
        QCAFRM_WAIT_RSVD_BYTE2 = QCAFRM_WAIT_AA4 - 4,

        /*  The frame length is used as the state until
         *  the end of the Ethernet frame
         *  Waiting for first 0x55 of footer
         */
        QCAFRM_WAIT_551 = 1,

        /*  Waiting for second 0x55 of footer */
        QCAFRM_WAIT_552 = QCAFRM_WAIT_551 - 1
};

/*   Structure to maintain the frame decoding during reception. */

struct qcafrm_handle {
        /*  Current decoding state */
        enum qcafrm_state state;
        /* Initial state depends on connection type */
        enum qcafrm_state init;

        /* Offset in buffer (borrowed for length too) */
        u16 offset;
};

u16 qcafrm_create_header(u8 *buf, u16 len);

u16 qcafrm_create_footer(u8 *buf);

static inline void qcafrm_fsm_init_spi(struct qcafrm_handle *handle)
{
        handle->init = QCAFRM_HW_LEN0;
        handle->state = handle->init;
}

static inline void qcafrm_fsm_init_uart(struct qcafrm_handle *handle)
{
        handle->init = QCAFRM_WAIT_AA1;
        handle->state = handle->init;
}

s32 qcafrm_fsm_decode(struct qcafrm_handle *handle, u8 *buf, u16 buf_len, u8 recv_byte);

#endif /* _QCA_FRAMING_H */