/* ir-sanyo-decoder.c - handle SANYO IR Pulse/Space protocol
 *
 * Copyright (C) 2011 by Mauro Carvalho Chehab
 *
 * 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.
 *
 * 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
 * @duration:   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;
        u8 address, command, not_command;

        if (!(dev->enabled_protocols & RC_BIT_SANYO))
                return 0;

        if (!is_timing_event(ev)) {
                if (ev.reset) {
                        IR_dprintk(1, "SANYO event reset received. reset to state 0\n");
                        data->state = STATE_INACTIVE;
                }
                return 0;
        }

        IR_dprintk(2, "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)) {
                        if (!dev->keypressed) {
                                IR_dprintk(1, "SANYO discarding last key repeat: event after key up\n");
                        } else {
                                rc_repeat(dev);
                                IR_dprintk(1, "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) {
                        IR_dprintk(1, "SANYO checksum error: received 0x%08Lx\n",
                                   data->bits);
                        data->state = STATE_INACTIVE;
                        return 0;
                }

                scancode = address << 8 | command;
                IR_dprintk(1, "SANYO scancode: 0x%06x\n", scancode);
                rc_keydown(dev, RC_TYPE_SANYO, scancode, 0);
                data->state = STATE_INACTIVE;
                return 0;
        }

        IR_dprintk(1, "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 struct ir_raw_handler sanyo_handler = {
        .protocols      = RC_BIT_SANYO,
        .decode         = ir_sanyo_decode,
};

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