// SPDX-License-Identifier: GPL-2.0-only
/* ir-mce_kbd-decoder.c - A decoder for the RC6-ish keyboard/mouse IR protocol
 * used by the Microsoft Remote Keyboard for Windows Media Center Edition,
 * referred to by Microsoft's Windows Media Center remote specification docs
 * as "an internal protocol called MCIR-2".
 *
 * Copyright (C) 2011 by Jarod Wilson <jarod@redhat.com>
 */
#include <linux/module.h>

#include "rc-core-priv.h"

/*
 * This decoder currently supports:
 * - MCIR-2 29-bit IR signals used for mouse movement and buttons
 * - MCIR-2 32-bit IR signals used for standard keyboard keys
 *
 * The media keys on the keyboard send RC-6 signals that are indistinguishable
 * from the keys of the same name on the stock MCE remote, and will be handled
 * by the standard RC-6 decoder, and be made available to the system via the
 * input device for the remote, rather than the keyboard/mouse one.
 */

#define MCIR2_UNIT              333     /* us */
#define MCIR2_HEADER_NBITS      5
#define MCIR2_MOUSE_NBITS       29
#define MCIR2_KEYBOARD_NBITS    32
#define MCIR2_PREFIX_PULSE      (8 * MCIR2_UNIT)
#define MCIR2_PREFIX_SPACE      (1 * MCIR2_UNIT)
#define MCIR2_MAX_LEN           (3 * MCIR2_UNIT)
#define MCIR2_BIT_START         (1 * MCIR2_UNIT)
#define MCIR2_BIT_END           (1 * MCIR2_UNIT)
#define MCIR2_BIT_0             (1 * MCIR2_UNIT)
#define MCIR2_BIT_SET           (2 * MCIR2_UNIT)
#define MCIR2_MODE_MASK         0xf     /* for the header bits */
#define MCIR2_KEYBOARD_HEADER   0x4
#define MCIR2_MOUSE_HEADER      0x1
#define MCIR2_MASK_KEYS_START   0xe0

enum mce_kbd_mode {
        MCIR2_MODE_KEYBOARD,
        MCIR2_MODE_MOUSE,
        MCIR2_MODE_UNKNOWN,
};

enum mce_kbd_state {
        STATE_INACTIVE,
        STATE_HEADER_BIT_START,
        STATE_HEADER_BIT_END,
        STATE_BODY_BIT_START,
        STATE_BODY_BIT_END,
        STATE_FINISHED,
};

static unsigned char kbd_keycodes[256] = {
        KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_A,
        KEY_B,          KEY_C,          KEY_D,          KEY_E,          KEY_F,
        KEY_G,          KEY_H,          KEY_I,          KEY_J,          KEY_K,
        KEY_L,          KEY_M,          KEY_N,          KEY_O,          KEY_P,
        KEY_Q,          KEY_R,          KEY_S,          KEY_T,          KEY_U,
        KEY_V,          KEY_W,          KEY_X,          KEY_Y,          KEY_Z,
        KEY_1,          KEY_2,          KEY_3,          KEY_4,          KEY_5,
        KEY_6,          KEY_7,          KEY_8,          KEY_9,          KEY_0,
        KEY_ENTER,      KEY_ESC,        KEY_BACKSPACE,  KEY_TAB,        KEY_SPACE,
        KEY_MINUS,      KEY_EQUAL,      KEY_LEFTBRACE,  KEY_RIGHTBRACE, KEY_BACKSLASH,
        KEY_BACKSLASH,  KEY_SEMICOLON,  KEY_APOSTROPHE, KEY_GRAVE,      KEY_COMMA,
        KEY_DOT,        KEY_SLASH,      KEY_CAPSLOCK,   KEY_F1,         KEY_F2,
        KEY_F3,         KEY_F4,         KEY_F5,         KEY_F6,         KEY_F7,
        KEY_F8,         KEY_F9,         KEY_F10,        KEY_F11,        KEY_F12,
        KEY_SYSRQ,      KEY_SCROLLLOCK, KEY_PAUSE,      KEY_INSERT,     KEY_HOME,
        KEY_PAGEUP,     KEY_DELETE,     KEY_END,        KEY_PAGEDOWN,   KEY_RIGHT,
        KEY_LEFT,       KEY_DOWN,       KEY_UP,         KEY_NUMLOCK,    KEY_KPSLASH,
        KEY_KPASTERISK, KEY_KPMINUS,    KEY_KPPLUS,     KEY_KPENTER,    KEY_KP1,
        KEY_KP2,        KEY_KP3,        KEY_KP4,        KEY_KP5,        KEY_KP6,
        KEY_KP7,        KEY_KP8,        KEY_KP9,        KEY_KP0,        KEY_KPDOT,
        KEY_102ND,      KEY_COMPOSE,    KEY_POWER,      KEY_KPEQUAL,    KEY_F13,
        KEY_F14,        KEY_F15,        KEY_F16,        KEY_F17,        KEY_F18,
        KEY_F19,        KEY_F20,        KEY_F21,        KEY_F22,        KEY_F23,
        KEY_F24,        KEY_OPEN,       KEY_HELP,       KEY_PROPS,      KEY_FRONT,
        KEY_STOP,       KEY_AGAIN,      KEY_UNDO,       KEY_CUT,        KEY_COPY,
        KEY_PASTE,      KEY_FIND,       KEY_MUTE,       KEY_VOLUMEUP,   KEY_VOLUMEDOWN,
        KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_KPCOMMA,    KEY_RESERVED,
        KEY_RO,         KEY_KATAKANAHIRAGANA, KEY_YEN,  KEY_HENKAN,     KEY_MUHENKAN,
        KEY_KPJPCOMMA,  KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_HANGUEL,
        KEY_HANJA,      KEY_KATAKANA,   KEY_HIRAGANA,   KEY_ZENKAKUHANKAKU, KEY_RESERVED,
        KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,
        KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,
        KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,
        KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,
        KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,
        KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,
        KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,
        KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,
        KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,
        KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,
        KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,
        KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,
        KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,
        KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,
        KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,   KEY_LEFTCTRL,
        KEY_LEFTSHIFT,  KEY_LEFTALT,    KEY_LEFTMETA,   KEY_RIGHTCTRL,  KEY_RIGHTSHIFT,
        KEY_RIGHTALT,   KEY_RIGHTMETA,  KEY_PLAYPAUSE,  KEY_STOPCD,     KEY_PREVIOUSSONG,
        KEY_NEXTSONG,   KEY_EJECTCD,    KEY_VOLUMEUP,   KEY_VOLUMEDOWN, KEY_MUTE,
        KEY_WWW,        KEY_BACK,       KEY_FORWARD,    KEY_STOP,       KEY_FIND,
        KEY_SCROLLUP,   KEY_SCROLLDOWN, KEY_EDIT,       KEY_SLEEP,      KEY_COFFEE,
        KEY_REFRESH,    KEY_CALC,       KEY_RESERVED,   KEY_RESERVED,   KEY_RESERVED,
        KEY_RESERVED
};

static void mce_kbd_rx_timeout(struct timer_list *t)
{
        struct ir_raw_event_ctrl *raw = timer_container_of(raw, t,
                                                           mce_kbd.rx_timeout);
        unsigned char maskcode;
        unsigned long flags;
        int i;

        dev_dbg(&raw->dev->dev, "timer callback clearing all keys\n");

        spin_lock_irqsave(&raw->mce_kbd.keylock, flags);

        if (time_is_before_eq_jiffies(raw->mce_kbd.rx_timeout.expires)) {
                for (i = 0; i < 7; i++) {
                        maskcode = kbd_keycodes[MCIR2_MASK_KEYS_START + i];
                        input_report_key(raw->dev->input_dev, maskcode, 0);
                }

                for (i = 0; i < MCIR2_MASK_KEYS_START; i++)
                        input_report_key(raw->dev->input_dev, kbd_keycodes[i],
                                         0);

                input_sync(raw->dev->input_dev);
        }
        spin_unlock_irqrestore(&raw->mce_kbd.keylock, flags);
}

static enum mce_kbd_mode mce_kbd_mode(struct mce_kbd_dec *data)
{
        switch (data->header & MCIR2_MODE_MASK) {
        case MCIR2_KEYBOARD_HEADER:
                return MCIR2_MODE_KEYBOARD;
        case MCIR2_MOUSE_HEADER:
                return MCIR2_MODE_MOUSE;
        default:
                return MCIR2_MODE_UNKNOWN;
        }
}

static void ir_mce_kbd_process_keyboard_data(struct rc_dev *dev, u32 scancode)
{
        u8 keydata1  = (scancode >> 8) & 0xff;
        u8 keydata2  = (scancode >> 16) & 0xff;
        u8 shiftmask = scancode & 0xff;
        unsigned char maskcode;
        int i, keystate;

        dev_dbg(&dev->dev, "keyboard: keydata2 = 0x%02x, keydata1 = 0x%02x, shiftmask = 0x%02x\n",
                keydata2, keydata1, shiftmask);

        for (i = 0; i < 7; i++) {
                maskcode = kbd_keycodes[MCIR2_MASK_KEYS_START + i];
                if (shiftmask & (1 << i))
                        keystate = 1;
                else
                        keystate = 0;
                input_report_key(dev->input_dev, maskcode, keystate);
        }

        if (keydata1)
                input_report_key(dev->input_dev, kbd_keycodes[keydata1], 1);
        if (keydata2)
                input_report_key(dev->input_dev, kbd_keycodes[keydata2], 1);

        if (!keydata1 && !keydata2) {
                for (i = 0; i < MCIR2_MASK_KEYS_START; i++)
                        input_report_key(dev->input_dev, kbd_keycodes[i], 0);
        }
}

static void ir_mce_kbd_process_mouse_data(struct rc_dev *dev, u32 scancode)
{
        /* raw mouse coordinates */
        u8 xdata = (scancode >> 7) & 0x7f;
        u8 ydata = (scancode >> 14) & 0x7f;
        int x, y;
        /* mouse buttons */
        bool right = scancode & 0x40;
        bool left  = scancode & 0x20;

        if (xdata & 0x40)
                x = -((~xdata & 0x7f) + 1);
        else
                x = xdata;

        if (ydata & 0x40)
                y = -((~ydata & 0x7f) + 1);
        else
                y = ydata;

        dev_dbg(&dev->dev, "mouse: x = %d, y = %d, btns = %s%s\n",
                x, y, left ? "L" : "", right ? "R" : "");

        input_report_rel(dev->input_dev, REL_X, x);
        input_report_rel(dev->input_dev, REL_Y, y);

        input_report_key(dev->input_dev, BTN_LEFT, left);
        input_report_key(dev->input_dev, BTN_RIGHT, right);
}

/**
 * ir_mce_kbd_decode() - Decode one mce_kbd 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_mce_kbd_decode(struct rc_dev *dev, struct ir_raw_event ev)
{
        struct mce_kbd_dec *data = &dev->raw->mce_kbd;
        u32 scancode;
        unsigned long delay;
        struct lirc_scancode lsc = {};

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

        if (!geq_margin(ev.duration, MCIR2_UNIT, MCIR2_UNIT / 2))
                goto out;

again:
        dev_dbg(&dev->dev, "started at state %i (%uus %s)\n",
                data->state, ev.duration, TO_STR(ev.pulse));

        if (!geq_margin(ev.duration, MCIR2_UNIT, MCIR2_UNIT / 2))
                return 0;

        switch (data->state) {

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

                /* Note: larger margin on first pulse since each MCIR2_UNIT
                   is quite short and some hardware takes some time to
                   adjust to the signal */
                if (!eq_margin(ev.duration, MCIR2_PREFIX_PULSE, MCIR2_UNIT))
                        break;

                data->state = STATE_HEADER_BIT_START;
                data->count = 0;
                data->header = 0;
                return 0;

        case STATE_HEADER_BIT_START:
                if (geq_margin(ev.duration, MCIR2_MAX_LEN, MCIR2_UNIT / 2))
                        break;

                data->header <<= 1;
                if (ev.pulse)
                        data->header |= 1;
                data->count++;
                data->state = STATE_HEADER_BIT_END;
                return 0;

        case STATE_HEADER_BIT_END:
                decrease_duration(&ev, MCIR2_BIT_END);

                if (data->count != MCIR2_HEADER_NBITS) {
                        data->state = STATE_HEADER_BIT_START;
                        goto again;
                }

                switch (mce_kbd_mode(data)) {
                case MCIR2_MODE_KEYBOARD:
                        data->wanted_bits = MCIR2_KEYBOARD_NBITS;
                        break;
                case MCIR2_MODE_MOUSE:
                        data->wanted_bits = MCIR2_MOUSE_NBITS;
                        break;
                default:
                        dev_dbg(&dev->dev, "not keyboard or mouse data\n");
                        goto out;
                }

                data->count = 0;
                data->body = 0;
                data->state = STATE_BODY_BIT_START;
                goto again;

        case STATE_BODY_BIT_START:
                if (geq_margin(ev.duration, MCIR2_MAX_LEN, MCIR2_UNIT / 2))
                        break;

                data->body <<= 1;
                if (ev.pulse)
                        data->body |= 1;
                data->count++;
                data->state = STATE_BODY_BIT_END;
                return 0;

        case STATE_BODY_BIT_END:
                if (data->count == data->wanted_bits)
                        data->state = STATE_FINISHED;
                else
                        data->state = STATE_BODY_BIT_START;

                decrease_duration(&ev, MCIR2_BIT_END);
                goto again;

        case STATE_FINISHED:
                if (ev.pulse)
                        break;

                switch (data->wanted_bits) {
                case MCIR2_KEYBOARD_NBITS:
                        scancode = data->body & 0xffffff;
                        dev_dbg(&dev->dev, "keyboard data 0x%08x\n",
                                data->body);
                        spin_lock(&data->keylock);
                        if (scancode) {
                                delay = usecs_to_jiffies(dev->timeout) +
                                        msecs_to_jiffies(100);
                                mod_timer(&data->rx_timeout, jiffies + delay);
                        } else {
                                timer_delete(&data->rx_timeout);
                        }
                        /* Pass data to keyboard buffer parser */
                        ir_mce_kbd_process_keyboard_data(dev, scancode);
                        spin_unlock(&data->keylock);
                        lsc.rc_proto = RC_PROTO_MCIR2_KBD;
                        break;
                case MCIR2_MOUSE_NBITS:
                        scancode = data->body & 0x1fffff;
                        dev_dbg(&dev->dev, "mouse data 0x%06x\n", scancode);
                        /* Pass data to mouse buffer parser */
                        ir_mce_kbd_process_mouse_data(dev, scancode);
                        lsc.rc_proto = RC_PROTO_MCIR2_MSE;
                        break;
                default:
                        dev_dbg(&dev->dev, "not keyboard or mouse data\n");
                        goto out;
                }

                lsc.scancode = scancode;
                lirc_scancode_event(dev, &lsc);
                data->state = STATE_INACTIVE;
                input_event(dev->input_dev, EV_MSC, MSC_SCAN, scancode);
                input_sync(dev->input_dev);
                return 0;
        }

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

static int ir_mce_kbd_register(struct rc_dev *dev)
{
        struct mce_kbd_dec *mce_kbd = &dev->raw->mce_kbd;

        timer_setup(&mce_kbd->rx_timeout, mce_kbd_rx_timeout, 0);
        spin_lock_init(&mce_kbd->keylock);

        return 0;
}

static int ir_mce_kbd_unregister(struct rc_dev *dev)
{
        struct mce_kbd_dec *mce_kbd = &dev->raw->mce_kbd;

        timer_delete_sync(&mce_kbd->rx_timeout);

        return 0;
}

static const struct ir_raw_timings_manchester ir_mce_kbd_timings = {
        .leader_pulse   = MCIR2_PREFIX_PULSE,
        .invert         = 1,
        .clock          = MCIR2_UNIT,
        .trailer_space  = MCIR2_UNIT * 10,
};

/**
 * ir_mce_kbd_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_mce_kbd_encode(enum rc_proto protocol, u32 scancode,
                             struct ir_raw_event *events, unsigned int max)
{
        struct ir_raw_event *e = events;
        int len, ret;
        u64 raw;

        if (protocol == RC_PROTO_MCIR2_KBD) {
                raw = scancode |
                      ((u64)MCIR2_KEYBOARD_HEADER << MCIR2_KEYBOARD_NBITS);
                len = MCIR2_KEYBOARD_NBITS + MCIR2_HEADER_NBITS;
        } else {
                raw = scancode |
                      ((u64)MCIR2_MOUSE_HEADER << MCIR2_MOUSE_NBITS);
                len = MCIR2_MOUSE_NBITS + MCIR2_HEADER_NBITS;
        }

        ret = ir_raw_gen_manchester(&e, max, &ir_mce_kbd_timings, len, raw);
        if (ret < 0)
                return ret;

        return e - events;
}

static struct ir_raw_handler mce_kbd_handler = {
        .protocols      = RC_PROTO_BIT_MCIR2_KBD | RC_PROTO_BIT_MCIR2_MSE,
        .decode         = ir_mce_kbd_decode,
        .encode         = ir_mce_kbd_encode,
        .raw_register   = ir_mce_kbd_register,
        .raw_unregister = ir_mce_kbd_unregister,
        .carrier        = 36000,
        .min_timeout    = MCIR2_MAX_LEN + MCIR2_UNIT / 2,
};

static int __init ir_mce_kbd_decode_init(void)
{
        ir_raw_handler_register(&mce_kbd_handler);

        printk(KERN_INFO "IR MCE Keyboard/mouse protocol handler initialized\n");
        return 0;
}

static void __exit ir_mce_kbd_decode_exit(void)
{
        ir_raw_handler_unregister(&mce_kbd_handler);
}

module_init(ir_mce_kbd_decode_init);
module_exit(ir_mce_kbd_decode_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jarod Wilson <jarod@redhat.com>");
MODULE_DESCRIPTION("MCE Keyboard/mouse IR protocol decoder");