// SPDX-License-Identifier: GPL-2.0
// ir-sanyo-decoder.c - handle SANYO IR Pulse/Space protocol
//
// Copyright (C) 2011 by Mauro Carvalho Chehab
//
// This protocol uses the NEC protocol timings. However, data is formatted as:
//      13 bits Custom Code
//      13 bits NOT(Custom Code)
//      8 bits Key data
//      8 bits NOT(Key data)
//
// According with LIRC, this protocol is used on Sanyo, Aiwa and Chinon
// Information for this protocol is available at the Sanyo LC7461 datasheet.

#include <linux/module.h>
#include <linux/bitrev.h>
#include "rc-core-priv.h"

#define SANYO_NBITS             (13+13+8+8)
#define SANYO_UNIT              562500  /* ns */
#define SANYO_HEADER_PULSE      (16  * SANYO_UNIT)
#define SANYO_HEADER_SPACE      (8   * SANYO_UNIT)
#define SANYO_BIT_PULSE         (1   * SANYO_UNIT)
#define SANYO_BIT_0_SPACE       (1   * SANYO_UNIT)
#define SANYO_BIT_1_SPACE       (3   * SANYO_UNIT)
#define SANYO_REPEAT_SPACE      (150 * SANYO_UNIT)
#define SANYO_TRAILER_PULSE     (1   * SANYO_UNIT)
#define SANYO_TRAILER_SPACE     (10  * SANYO_UNIT)      /* in fact, 42 */

enum sanyo_state {
        STATE_INACTIVE,
        STATE_HEADER_SPACE,
        STATE_BIT_PULSE,
        STATE_BIT_SPACE,
        STATE_TRAILER_PULSE,
        STATE_TRAILER_SPACE,
};

/**
 * ir_sanyo_decode() - Decode one SANYO 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
 */
static int ir_sanyo_decode(struct rc_dev *dev, struct ir_raw_event ev)
{
        struct sanyo_dec *data = &dev->raw->sanyo;
        u32 scancode;
        u16 address;
        u8 command, not_command;

        if (!is_timing_event(ev)) {
                if (ev.reset) {
                        dev_dbg(&dev->dev, "SANYO event reset received. reset to state 0\n");
                        data->state = STATE_INACTIVE;
                }
                return 0;
        }

        dev_dbg(&dev->dev, "SANYO decode started at state %d (%uus %s)\n",
                data->state, TO_US(ev.duration), TO_STR(ev.pulse));

        switch (data->state) {

        case STATE_INACTIVE:
                if (!ev.pulse)
                        break;

                if (eq_margin(ev.duration, SANYO_HEADER_PULSE, SANYO_UNIT / 2)) {
                        data->count = 0;
                        data->state = STATE_HEADER_SPACE;
                        return 0;
                }
                break;


        case STATE_HEADER_SPACE:
                if (ev.pulse)
                        break;

                if (eq_margin(ev.duration, SANYO_HEADER_SPACE, SANYO_UNIT / 2)) {
                        data->state = STATE_BIT_PULSE;
                        return 0;
                }

                break;

        case STATE_BIT_PULSE:
                if (!ev.pulse)
                        break;

                if (!eq_margin(ev.duration, SANYO_BIT_PULSE, SANYO_UNIT / 2))
                        break;

                data->state = STATE_BIT_SPACE;
                return 0;

        case STATE_BIT_SPACE:
                if (ev.pulse)
                        break;

                if (!data->count && geq_margin(ev.duration, SANYO_REPEAT_SPACE, SANYO_UNIT / 2)) {
                        rc_repeat(dev);
                        dev_dbg(&dev->dev, "SANYO repeat last key\n");
                        data->state = STATE_INACTIVE;
                        return 0;
                }

                data->bits <<= 1;
                if (eq_margin(ev.duration, SANYO_BIT_1_SPACE, SANYO_UNIT / 2))
                        data->bits |= 1;
                else if (!eq_margin(ev.duration, SANYO_BIT_0_SPACE, SANYO_UNIT / 2))
                        break;
                data->count++;

                if (data->count == SANYO_NBITS)
                        data->state = STATE_TRAILER_PULSE;
                else
                        data->state = STATE_BIT_PULSE;

                return 0;

        case STATE_TRAILER_PULSE:
                if (!ev.pulse)
                        break;

                if (!eq_margin(ev.duration, SANYO_TRAILER_PULSE, SANYO_UNIT / 2))
                        break;

                data->state = STATE_TRAILER_SPACE;
                return 0;

        case STATE_TRAILER_SPACE:
                if (ev.pulse)
                        break;

                if (!geq_margin(ev.duration, SANYO_TRAILER_SPACE, SANYO_UNIT / 2))
                        break;

                address     = bitrev16((data->bits >> 29) & 0x1fff) >> 3;
                /* not_address = bitrev16((data->bits >> 16) & 0x1fff) >> 3; */
                command     = bitrev8((data->bits >>  8) & 0xff);
                not_command = bitrev8((data->bits >>  0) & 0xff);

                if ((command ^ not_command) != 0xff) {
                        dev_dbg(&dev->dev, "SANYO checksum error: received 0x%08llx\n",
                                data->bits);
                        data->state = STATE_INACTIVE;
                        return 0;
                }

                scancode = address << 8 | command;
                dev_dbg(&dev->dev, "SANYO scancode: 0x%06x\n", scancode);
                rc_keydown(dev, RC_PROTO_SANYO, scancode, 0);
                data->state = STATE_INACTIVE;
                return 0;
        }

        dev_dbg(&dev->dev, "SANYO decode failed at count %d state %d (%uus %s)\n",
                data->count, data->state, TO_US(ev.duration), TO_STR(ev.pulse));
        data->state = STATE_INACTIVE;
        return -EINVAL;
}

static const struct ir_raw_timings_pd ir_sanyo_timings = {
        .header_pulse  = SANYO_HEADER_PULSE,
        .header_space  = SANYO_HEADER_SPACE,
        .bit_pulse     = SANYO_BIT_PULSE,
        .bit_space[0]  = SANYO_BIT_0_SPACE,
        .bit_space[1]  = SANYO_BIT_1_SPACE,
        .trailer_pulse = SANYO_TRAILER_PULSE,
        .trailer_space = SANYO_TRAILER_SPACE,
        .msb_first     = 1,
};

/**
 * ir_sanyo_encode() - Encode a scancode as a stream of raw events
 *
 * @protocol:   protocol to encode
 * @scancode:   scancode to encode
 * @events:     array of raw ir events to write into
 * @max:        maximum size of @events
 *
 * Returns:     The number of events written.
 *              -ENOBUFS if there isn't enough space in the array to fit the
 *              encoding. In this case all @max events will have been written.
 */
static int ir_sanyo_encode(enum rc_proto protocol, u32 scancode,
                           struct ir_raw_event *events, unsigned int max)
{
        struct ir_raw_event *e = events;
        int ret;
        u64 raw;

        raw = ((u64)(bitrev16(scancode >> 8) & 0xfff8) << (8 + 8 + 13 - 3)) |
              ((u64)(bitrev16(~scancode >> 8) & 0xfff8) << (8 + 8 +  0 - 3)) |
              ((bitrev8(scancode) & 0xff) << 8) |
              (bitrev8(~scancode) & 0xff);

        ret = ir_raw_gen_pd(&e, max, &ir_sanyo_timings, SANYO_NBITS, raw);
        if (ret < 0)
                return ret;

        return e - events;
}

static struct ir_raw_handler sanyo_handler = {
        .protocols      = RC_PROTO_BIT_SANYO,
        .decode         = ir_sanyo_decode,
        .encode         = ir_sanyo_encode,
        .carrier        = 38000,
        .min_timeout    = SANYO_TRAILER_SPACE,
};

static int __init ir_sanyo_decode_init(void)
{
        ir_raw_handler_register(&sanyo_handler);

        printk(KERN_INFO "IR SANYO protocol handler initialized\n");
        return 0;
}

static void __exit ir_sanyo_decode_exit(void)
{
        ir_raw_handler_unregister(&sanyo_handler);
}

module_init(ir_sanyo_decode_init);
module_exit(ir_sanyo_decode_exit);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Mauro Carvalho Chehab");
MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
MODULE_DESCRIPTION("SANYO IR protocol decoder");