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/*
* Copyright (c) 2011, 2012, Atheros Communications Inc.
* Copyright (c) 2014, I2SE GmbH
*
* Permission to use, copy, modify, and/or distribute this software
* for any purpose with or without fee is hereby granted, provided
* that the above copyright notice and this permission notice appear
* in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
* WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
* THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/* Atheros ethernet framing. Every Ethernet frame is surrounded
* by an atheros frame while transmitted over a serial channel;
*/
#include <linux/kernel.h>
#include "qca_framing.h"
u16
qcafrm_create_header(u8 *buf, u16 length)
{
__le16 len;
if (!buf)
return 0;
len = cpu_to_le16(length);
buf[0] = 0xAA;
buf[1] = 0xAA;
buf[2] = 0xAA;
buf[3] = 0xAA;
buf[4] = len & 0xff;
buf[5] = (len >> 8) & 0xff;
buf[6] = 0;
buf[7] = 0;
return QCAFRM_HEADER_LEN;
}
u16
qcafrm_create_footer(u8 *buf)
{
if (!buf)
return 0;
buf[0] = 0x55;
buf[1] = 0x55;
return QCAFRM_FOOTER_LEN;
}
/* Gather received bytes and try to extract a full ethernet frame by
* following a simple state machine.
*
* Return: QCAFRM_GATHER No ethernet frame fully received yet.
* QCAFRM_NOHEAD Header expected but not found.
* QCAFRM_INVLEN Atheros frame length is invalid
* QCAFRM_NOTAIL Footer expected but not found.
* > 0 Number of byte in the fully received
* Ethernet frame
*/
s32
qcafrm_fsm_decode(struct qcafrm_handle *handle, u8 *buf, u16 buf_len, u8 recv_byte)
{
s32 ret = QCAFRM_GATHER;
u16 len;
switch (handle->state) {
case QCAFRM_HW_LEN0:
case QCAFRM_HW_LEN1:
/* by default, just go to next state */
handle->state--;
if (recv_byte != 0x00) {
/* first two bytes of length must be 0 */
handle->state = QCAFRM_HW_LEN0;
}
break;
case QCAFRM_HW_LEN2:
case QCAFRM_HW_LEN3:
handle->state--;
break;
/* 4 bytes header pattern */
case QCAFRM_WAIT_AA1:
case QCAFRM_WAIT_AA2:
case QCAFRM_WAIT_AA3:
case QCAFRM_WAIT_AA4:
if (recv_byte != 0xAA) {
ret = QCAFRM_NOHEAD;
handle->state = QCAFRM_HW_LEN0;
} else {
handle->state--;
}
break;
/* 2 bytes length. */
/* Borrow offset field to hold length for now. */
case QCAFRM_WAIT_LEN_BYTE0:
handle->offset = recv_byte;
handle->state = QCAFRM_WAIT_LEN_BYTE1;
break;
case QCAFRM_WAIT_LEN_BYTE1:
handle->offset = handle->offset | (recv_byte << 8);
handle->state = QCAFRM_WAIT_RSVD_BYTE1;
break;
case QCAFRM_WAIT_RSVD_BYTE1:
handle->state = QCAFRM_WAIT_RSVD_BYTE2;
break;
case QCAFRM_WAIT_RSVD_BYTE2:
len = handle->offset;
if (len > buf_len || len < QCAFRM_ETHMINLEN) {
ret = QCAFRM_INVLEN;
handle->state = QCAFRM_HW_LEN0;
} else {
handle->state = (enum qcafrm_state)(len + 1);
/* Remaining number of bytes. */
handle->offset = 0;
}
break;
default:
/* Receiving Ethernet frame itself. */
buf[handle->offset] = recv_byte;
handle->offset++;
handle->state--;
break;
case QCAFRM_WAIT_551:
if (recv_byte != 0x55) {
ret = QCAFRM_NOTAIL;
handle->state = QCAFRM_HW_LEN0;
} else {
handle->state = QCAFRM_WAIT_552;
}
break;
case QCAFRM_WAIT_552:
if (recv_byte != 0x55) {
ret = QCAFRM_NOTAIL;
handle->state = QCAFRM_HW_LEN0;
} else {
ret = handle->offset;
/* Frame is fully received. */
handle->state = QCAFRM_HW_LEN0;
}
break;
}
return ret;
}
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