/* ir-sony-decoder.c - handle Sony IR Pulse/Space protocol
 *
 * Copyright (C) 2010 by David Härdeman <david@hardeman.nu>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

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

#define SONY_UNIT               600000 /* ns */
#define SONY_HEADER_PULSE       (4 * SONY_UNIT)
#define SONY_HEADER_SPACE       (1 * SONY_UNIT)
#define SONY_BIT_0_PULSE        (1 * SONY_UNIT)
#define SONY_BIT_1_PULSE        (2 * SONY_UNIT)
#define SONY_BIT_SPACE          (1 * SONY_UNIT)
#define SONY_TRAILER_SPACE      (10 * SONY_UNIT) /* minimum */

enum sony_state {
        STATE_INACTIVE,
        STATE_HEADER_SPACE,
        STATE_BIT_PULSE,
        STATE_BIT_SPACE,
        STATE_FINISHED,
};

/**
 * ir_sony_decode() - Decode one Sony 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_sony_decode(struct rc_dev *dev, struct ir_raw_event ev)
{
        struct sony_dec *data = &dev->raw->sony;
        enum rc_proto protocol;
        u32 scancode;
        u8 device, subdevice, function;

        if (!is_timing_event(ev)) {
                if (ev.reset)
                        data->state = STATE_INACTIVE;
                return 0;
        }

        if (!geq_margin(ev.duration, SONY_UNIT, SONY_UNIT / 2))
                goto out;

        dev_dbg(&dev->dev, "Sony 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, SONY_HEADER_PULSE, SONY_UNIT / 2))
                        break;

                data->count = 0;
                data->state = STATE_HEADER_SPACE;
                return 0;

        case STATE_HEADER_SPACE:
                if (ev.pulse)
                        break;

                if (!eq_margin(ev.duration, SONY_HEADER_SPACE, SONY_UNIT / 2))
                        break;

                data->state = STATE_BIT_PULSE;
                return 0;

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

                data->bits <<= 1;
                if (eq_margin(ev.duration, SONY_BIT_1_PULSE, SONY_UNIT / 2))
                        data->bits |= 1;
                else if (!eq_margin(ev.duration, SONY_BIT_0_PULSE, SONY_UNIT / 2))
                        break;

                data->count++;
                data->state = STATE_BIT_SPACE;
                return 0;

        case STATE_BIT_SPACE:
                if (ev.pulse)
                        break;

                if (!geq_margin(ev.duration, SONY_BIT_SPACE, SONY_UNIT / 2))
                        break;

                decrease_duration(&ev, SONY_BIT_SPACE);

                if (!geq_margin(ev.duration, SONY_UNIT, SONY_UNIT / 2)) {
                        data->state = STATE_BIT_PULSE;
                        return 0;
                }

                data->state = STATE_FINISHED;
                /* Fall through */

        case STATE_FINISHED:
                if (ev.pulse)
                        break;

                if (!geq_margin(ev.duration, SONY_TRAILER_SPACE, SONY_UNIT / 2))
                        break;

                switch (data->count) {
                case 12:
                        if (!(dev->enabled_protocols & RC_PROTO_BIT_SONY12))
                                goto finish_state_machine;

                        device    = bitrev8((data->bits <<  3) & 0xF8);
                        subdevice = 0;
                        function  = bitrev8((data->bits >>  4) & 0xFE);
                        protocol = RC_PROTO_SONY12;
                        break;
                case 15:
                        if (!(dev->enabled_protocols & RC_PROTO_BIT_SONY15))
                                goto finish_state_machine;

                        device    = bitrev8((data->bits >>  0) & 0xFF);
                        subdevice = 0;
                        function  = bitrev8((data->bits >>  7) & 0xFE);
                        protocol = RC_PROTO_SONY15;
                        break;
                case 20:
                        if (!(dev->enabled_protocols & RC_PROTO_BIT_SONY20))
                                goto finish_state_machine;

                        device    = bitrev8((data->bits >>  5) & 0xF8);
                        subdevice = bitrev8((data->bits >>  0) & 0xFF);
                        function  = bitrev8((data->bits >> 12) & 0xFE);
                        protocol = RC_PROTO_SONY20;
                        break;
                default:
                        dev_dbg(&dev->dev, "Sony invalid bitcount %u\n",
                                data->count);
                        goto out;
                }

                scancode = device << 16 | subdevice << 8 | function;
                dev_dbg(&dev->dev, "Sony(%u) scancode 0x%05x\n", data->count,
                        scancode);
                rc_keydown(dev, protocol, scancode, 0);
                goto finish_state_machine;
        }

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

finish_state_machine:
        data->state = STATE_INACTIVE;
        return 0;
}

static const struct ir_raw_timings_pl ir_sony_timings = {
        .header_pulse  = SONY_HEADER_PULSE,
        .bit_space     = SONY_BIT_SPACE,
        .bit_pulse[0]  = SONY_BIT_0_PULSE,
        .bit_pulse[1]  = SONY_BIT_1_PULSE,
        .trailer_space = SONY_TRAILER_SPACE + SONY_BIT_SPACE,
        .msb_first     = 0,
};

/**
 * ir_sony_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_sony_encode(enum rc_proto protocol, u32 scancode,
                          struct ir_raw_event *events, unsigned int max)
{
        struct ir_raw_event *e = events;
        u32 raw, len;
        int ret;

        if (protocol == RC_PROTO_SONY12) {
                raw = (scancode & 0x7f) | ((scancode & 0x1f0000) >> 9);
                len = 12;
        } else if (protocol == RC_PROTO_SONY15) {
                raw = (scancode & 0x7f) | ((scancode & 0xff0000) >> 9);
                len = 15;
        } else {
                raw = (scancode & 0x7f) | ((scancode & 0x1f0000) >> 9) |
                       ((scancode & 0xff00) << 4);
                len = 20;
        }

        ret = ir_raw_gen_pl(&e, max, &ir_sony_timings, len, raw);
        if (ret < 0)
                return ret;

        return e - events;
}

static struct ir_raw_handler sony_handler = {
        .protocols      = RC_PROTO_BIT_SONY12 | RC_PROTO_BIT_SONY15 |
                                                        RC_PROTO_BIT_SONY20,
        .decode         = ir_sony_decode,
        .encode         = ir_sony_encode,
        .carrier        = 40000,
        .min_timeout    = SONY_TRAILER_SPACE,
};

static int __init ir_sony_decode_init(void)
{
        ir_raw_handler_register(&sony_handler);

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

static void __exit ir_sony_decode_exit(void)
{
        ir_raw_handler_unregister(&sony_handler);
}

module_init(ir_sony_decode_init);
module_exit(ir_sony_decode_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
MODULE_DESCRIPTION("Sony IR protocol decoder");