// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * ImgTec IR Decoder setup for Philips RC-6 protocol.
 *
 * Copyright 2012-2014 Imagination Technologies Ltd.
 */

#include "img-ir-hw.h"

/* Convert RC6 data to a scancode */
static int img_ir_rc6_scancode(int len, u64 raw, u64 enabled_protocols,
                                struct img_ir_scancode_req *request)
{
        unsigned int addr, cmd, mode, trl1, trl2;

        /*
         * Due to a side effect of the decoder handling the double length
         * Trailer bit, the header information is a bit scrambled, and the
         * raw data is shifted incorrectly.
         * This workaround effectively recovers the header bits.
         *
         * The Header field should look like this:
         *
         * StartBit ModeBit2 ModeBit1 ModeBit0 TrailerBit
         *
         * But what we get is:
         *
         * ModeBit2 ModeBit1 ModeBit0 TrailerBit1 TrailerBit2
         *
         * The start bit is not important to recover the scancode.
         */

        raw     >>= 27;

        trl1    = (raw >>  17)  & 0x01;
        trl2    = (raw >>  16)  & 0x01;

        mode    = (raw >>  18)  & 0x07;
        addr    = (raw >>   8)  & 0xff;
        cmd     =  raw          & 0xff;

        /*
         * Due to the above explained irregularity the trailer bits cannot
         * have the same value.
         */
        if (trl1 == trl2)
                return -EINVAL;

        /* Only mode 0 supported for now */
        if (mode)
                return -EINVAL;

        request->protocol = RC_PROTO_RC6_0;
        request->scancode = addr << 8 | cmd;
        request->toggle   = trl2;
        return IMG_IR_SCANCODE;
}

/* Convert RC6 scancode to RC6 data filter */
static int img_ir_rc6_filter(const struct rc_scancode_filter *in,
                                 struct img_ir_filter *out, u64 protocols)
{
        /* Not supported by the hw. */
        return -EINVAL;
}

/*
 * RC-6 decoder
 * see http://www.sbprojects.com/knowledge/ir/rc6.php
 */
struct img_ir_decoder img_ir_rc6 = {
        .type           = RC_PROTO_BIT_RC6_0,
        .control        = {
                .bitorien       = 1,
                .code_type      = IMG_IR_CODETYPE_BIPHASE,
                .decoden        = 1,
                .decodinpol     = 1,
        },
        /* main timings */
        .tolerance      = 20,
        /*
         * Due to a quirk in the img-ir decoder, default header values do
         * not work, the values described below were extracted from
         * successful RTL test cases.
         */
        .timings        = {
                /* leader symbol */
                .ldr = {
                        .pulse  = { 650 },
                        .space  = { 660 },
                },
                /* 0 symbol */
                .s00 = {
                        .pulse  = { 370 },
                        .space  = { 370 },
                },
                /* 01 symbol */
                .s01 = {
                        .pulse  = { 370 },
                        .space  = { 370 },
                },
                /* free time */
                .ft  = {
                        .minlen = 21,
                        .maxlen = 21,
                        .ft_min = 2666, /* 2.666 ms */
                },
        },

        /* scancode logic */
        .scancode       = img_ir_rc6_scancode,
        .filter         = img_ir_rc6_filter,
};