linux-imx

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

// ir-imon-decoder.c - handle iMon protocol

//

// Copyright (C) 2018 by Sean Young <sean@mess.org>

​

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

​

#include <linux/module.h>

#include "rc-core-priv.h"

​

#define IMON_UNIT       415662 /* ns */

#define IMON_BITS       30

#define IMON_CHKBITS        (BIT(30) | BIT(25) | BIT(24) | BIT(22) | \

                 BIT(21) | BIT(20) | BIT(19) | BIT(18) | \

                 BIT(17) | BIT(16) | BIT(14) | BIT(13) | \

                 BIT(12) | BIT(11) | BIT(10) | BIT(9))

​

/*

 * This protocol has 30 bits. The format is one IMON_UNIT header pulse,

 * followed by 30 bits. Each bit is one IMON_UNIT check field, and then

 * one IMON_UNIT field with the actual bit (1=space, 0=pulse).

 * The check field is always space for some bits, for others it is pulse if

 * both the preceding and current bit are zero, else space. IMON_CHKBITS

 * defines which bits are of type check.

 *

 * There is no way to distinguish an incomplete message from one where

 * the lower bits are all set, iow. the last pulse is for the lowest

 * bit which is 0.

 */

enum imon_state {

    STATE_INACTIVE,

    STATE_BIT_CHK,

    STATE_BIT_START,

    STATE_FINISHED,

    STATE_ERROR,

};

​

static void ir_imon_decode_scancode(struct rc_dev *dev)

{

    struct imon_dec *imon = &dev->raw->imon;

​

    /* Keyboard/Mouse toggle */

    if (imon->bits == 0x299115b7)

        imon->stick_keyboard = !imon->stick_keyboard;

​

    if ((imon->bits & 0xfc0000ff) == 0x680000b7) {

        int rel_x, rel_y;

        u8 buf;

​

        buf = imon->bits >> 16;

        rel_x = (buf & 0x08) | (buf & 0x10) >> 2 |

            (buf & 0x20) >> 4 | (buf & 0x40) >> 6;

        if (imon->bits & 0x02000000)

            rel_x |= ~0x0f;

        buf = imon->bits >> 8;

        rel_y = (buf & 0x08) | (buf & 0x10) >> 2 |

            (buf & 0x20) >> 4 | (buf & 0x40) >> 6;

        if (imon->bits & 0x01000000)

            rel_y |= ~0x0f;

​

        if (rel_x && rel_y && imon->stick_keyboard) {

            if (abs(rel_y) > abs(rel_x))

                imon->bits = rel_y > 0 ?

                    0x289515b7 : /* KEY_DOWN */

                    0x2aa515b7;  /* KEY_UP */

            else

                imon->bits = rel_x > 0 ?

                    0x2ba515b7 : /* KEY_RIGHT */

                    0x29a515b7;  /* KEY_LEFT */

        }

​

        if (!imon->stick_keyboard) {

            input_report_rel(dev->input_dev, REL_X, rel_x);

            input_report_rel(dev->input_dev, REL_Y, rel_y);

​

            input_report_key(dev->input_dev, BTN_LEFT,

                     (imon->bits & 0x00010000) != 0);

            input_report_key(dev->input_dev, BTN_RIGHT,

                     (imon->bits & 0x00040000) != 0);

        }

    }

​

    rc_keydown(dev, RC_PROTO_IMON, imon->bits, 0);

}

​

/**

 * ir_imon_decode() - Decode one iMON pulse or space

 * @dev:    the struct rc_dev descriptor of the device

 * @ev:     the struct ir_raw_event descriptor of the pulse/space

 *

 * This function returns -EINVAL if the pulse violates the state machine

 */