ir-mce_kbd-decoder.c

// 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 = from_timer(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 {
				del_timer(&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;

	del_timer_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");