linux-imx

// SPDX-License-Identifier: GPL-2.0+

​

/*

 * Multifunction core driver for Zodiac Inflight Innovations RAVE

 * Supervisory Processor(SP) MCU that is connected via dedicated UART

 * port

 *

 * Copyright (C) 2017 Zodiac Inflight Innovations

 */

​

#include <linux/atomic.h>

#include <linux/crc-ccitt.h>

#include <linux/delay.h>

#include <linux/export.h>

#include <linux/init.h>

#include <linux/slab.h>

#include <linux/kernel.h>

#include <linux/mfd/rave-sp.h>

#include <linux/module.h>

#include <linux/of.h>

#include <linux/of_device.h>

#include <linux/sched.h>

#include <linux/serdev.h>

#include <asm/unaligned.h>

​

/*

 * UART protocol using following entities:

 *  - message to MCU => ACK response

 *  - event from MCU => event ACK

 *

 * Frame structure:

 * <STX> <DATA> <CHECKSUM> <ETX>

 * Where:

 * - STX - is start of transmission character

 * - ETX - end of transmission

 * - DATA - payload

 * - CHECKSUM - checksum calculated on <DATA>

 *

 * If <DATA> or <CHECKSUM> contain one of control characters, then it is

 * escaped using <DLE> control code. Added <DLE> does not participate in

 * checksum calculation.

 */

#define RAVE_SP_STX         0x02

#define RAVE_SP_ETX         0x03

#define RAVE_SP_DLE         0x10

​

#define RAVE_SP_MAX_DATA_SIZE       64

#define RAVE_SP_CHECKSUM_8B2C       1

#define RAVE_SP_CHECKSUM_CCITT      2

#define RAVE_SP_CHECKSUM_SIZE       RAVE_SP_CHECKSUM_CCITT

/*

 * We don't store STX, ETX and unescaped bytes, so Rx is only

 * DATA + CSUM

 */

#define RAVE_SP_RX_BUFFER_SIZE              \

    (RAVE_SP_MAX_DATA_SIZE + RAVE_SP_CHECKSUM_SIZE)

​

#define RAVE_SP_STX_ETX_SIZE        2

/*

 * For Tx we have to have space for everything, STX, EXT and

 * potentially stuffed DATA + CSUM data + csum

 */

#define RAVE_SP_TX_BUFFER_SIZE              \