270 lines
6.5 KiB
C
270 lines
6.5 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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// ir-imon-decoder.c - handle iMon protocol
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//
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// Copyright (C) 2018 by Sean Young <sean@mess.org>
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include "rc-core-priv.h"
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#define IMON_UNIT 415662 /* ns */
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#define IMON_BITS 30
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#define IMON_CHKBITS (BIT(30) | BIT(25) | BIT(24) | BIT(22) | \
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BIT(21) | BIT(20) | BIT(19) | BIT(18) | \
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BIT(17) | BIT(16) | BIT(14) | BIT(13) | \
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BIT(12) | BIT(11) | BIT(10) | BIT(9))
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/*
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* This protocol has 30 bits. The format is one IMON_UNIT header pulse,
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* followed by 30 bits. Each bit is one IMON_UNIT check field, and then
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* one IMON_UNIT field with the actual bit (1=space, 0=pulse).
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* The check field is always space for some bits, for others it is pulse if
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* both the preceding and current bit are zero, else space. IMON_CHKBITS
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* defines which bits are of type check.
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*
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* There is no way to distinguish an incomplete message from one where
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* the lower bits are all set, iow. the last pulse is for the lowest
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* bit which is 0.
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*/
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enum imon_state {
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STATE_INACTIVE,
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STATE_BIT_CHK,
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STATE_BIT_START,
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STATE_FINISHED,
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STATE_ERROR,
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};
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static void ir_imon_decode_scancode(struct rc_dev *dev)
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{
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struct imon_dec *imon = &dev->raw->imon;
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/* Keyboard/Mouse toggle */
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if (imon->bits == 0x299115b7)
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imon->stick_keyboard = !imon->stick_keyboard;
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if ((imon->bits & 0xfc0000ff) == 0x680000b7) {
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int rel_x, rel_y;
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u8 buf;
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buf = imon->bits >> 16;
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rel_x = (buf & 0x08) | (buf & 0x10) >> 2 |
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(buf & 0x20) >> 4 | (buf & 0x40) >> 6;
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if (imon->bits & 0x02000000)
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rel_x |= ~0x0f;
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buf = imon->bits >> 8;
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rel_y = (buf & 0x08) | (buf & 0x10) >> 2 |
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(buf & 0x20) >> 4 | (buf & 0x40) >> 6;
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if (imon->bits & 0x01000000)
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rel_y |= ~0x0f;
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if (rel_x && rel_y && imon->stick_keyboard) {
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if (abs(rel_y) > abs(rel_x))
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imon->bits = rel_y > 0 ?
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0x289515b7 : /* KEY_DOWN */
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0x2aa515b7; /* KEY_UP */
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else
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imon->bits = rel_x > 0 ?
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0x2ba515b7 : /* KEY_RIGHT */
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0x29a515b7; /* KEY_LEFT */
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}
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if (!imon->stick_keyboard) {
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input_report_rel(dev->input_dev, REL_X, rel_x);
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input_report_rel(dev->input_dev, REL_Y, rel_y);
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input_report_key(dev->input_dev, BTN_LEFT,
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(imon->bits & 0x00010000) != 0);
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input_report_key(dev->input_dev, BTN_RIGHT,
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(imon->bits & 0x00040000) != 0);
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}
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}
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rc_keydown(dev, RC_PROTO_IMON, imon->bits, 0);
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}
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/**
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* ir_imon_decode() - Decode one iMON pulse or space
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* @dev: the struct rc_dev descriptor of the device
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* @ev: the struct ir_raw_event descriptor of the pulse/space
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*
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* This function returns -EINVAL if the pulse violates the state machine
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*/
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static int ir_imon_decode(struct rc_dev *dev, struct ir_raw_event ev)
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{
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struct imon_dec *data = &dev->raw->imon;
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if (!is_timing_event(ev)) {
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if (ev.reset)
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data->state = STATE_INACTIVE;
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return 0;
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}
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dev_dbg(&dev->dev,
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"iMON decode started at state %d bitno %d (%uus %s)\n",
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data->state, data->count, TO_US(ev.duration),
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TO_STR(ev.pulse));
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/*
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* Since iMON protocol is a series of bits, if at any point
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* we encounter an error, make sure that any remaining bits
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* aren't parsed as a scancode made up of less bits.
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*
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* Note that if the stick is held, then the remote repeats
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* the scancode with about 12ms between them. So, make sure
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* we have at least 10ms of space after an error. That way,
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* we're at a new scancode.
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*/
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if (data->state == STATE_ERROR) {
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if (!ev.pulse && ev.duration > MS_TO_NS(10))
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data->state = STATE_INACTIVE;
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return 0;
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}
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for (;;) {
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if (!geq_margin(ev.duration, IMON_UNIT, IMON_UNIT / 2))
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return 0;
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decrease_duration(&ev, IMON_UNIT);
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switch (data->state) {
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case STATE_INACTIVE:
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if (ev.pulse) {
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data->state = STATE_BIT_CHK;
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data->bits = 0;
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data->count = IMON_BITS;
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}
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break;
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case STATE_BIT_CHK:
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if (IMON_CHKBITS & BIT(data->count))
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data->last_chk = ev.pulse;
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else if (ev.pulse)
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goto err_out;
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data->state = STATE_BIT_START;
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break;
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case STATE_BIT_START:
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data->bits <<= 1;
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if (!ev.pulse)
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data->bits |= 1;
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if (IMON_CHKBITS & BIT(data->count)) {
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if (data->last_chk != !(data->bits & 3))
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goto err_out;
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}
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if (!data->count--)
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data->state = STATE_FINISHED;
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else
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data->state = STATE_BIT_CHK;
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break;
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case STATE_FINISHED:
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if (ev.pulse)
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goto err_out;
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ir_imon_decode_scancode(dev);
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data->state = STATE_INACTIVE;
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break;
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}
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}
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err_out:
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dev_dbg(&dev->dev,
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"iMON decode failed at state %d bitno %d (%uus %s)\n",
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data->state, data->count, TO_US(ev.duration),
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TO_STR(ev.pulse));
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data->state = STATE_ERROR;
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return -EINVAL;
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}
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/**
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* ir_imon_encode() - Encode a scancode as a stream of raw events
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*
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* @protocol: protocol to encode
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* @scancode: scancode to encode
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* @events: array of raw ir events to write into
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* @max: maximum size of @events
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*
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* Returns: The number of events written.
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* -ENOBUFS if there isn't enough space in the array to fit the
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* encoding. In this case all @max events will have been written.
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*/
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static int ir_imon_encode(enum rc_proto protocol, u32 scancode,
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struct ir_raw_event *events, unsigned int max)
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{
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struct ir_raw_event *e = events;
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int i, pulse;
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if (!max--)
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return -ENOBUFS;
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init_ir_raw_event_duration(e, 1, IMON_UNIT);
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for (i = IMON_BITS; i >= 0; i--) {
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if (BIT(i) & IMON_CHKBITS)
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pulse = !(scancode & (BIT(i) | BIT(i + 1)));
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else
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pulse = 0;
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if (pulse == e->pulse) {
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e->duration += IMON_UNIT;
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} else {
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if (!max--)
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return -ENOBUFS;
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init_ir_raw_event_duration(++e, pulse, IMON_UNIT);
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}
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pulse = !(scancode & BIT(i));
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if (pulse == e->pulse) {
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e->duration += IMON_UNIT;
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} else {
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if (!max--)
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return -ENOBUFS;
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init_ir_raw_event_duration(++e, pulse, IMON_UNIT);
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}
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}
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if (e->pulse)
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e++;
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return e - events;
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}
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static int ir_imon_register(struct rc_dev *dev)
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{
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struct imon_dec *imon = &dev->raw->imon;
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imon->stick_keyboard = false;
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return 0;
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}
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static struct ir_raw_handler imon_handler = {
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.protocols = RC_PROTO_BIT_IMON,
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.decode = ir_imon_decode,
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.encode = ir_imon_encode,
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.carrier = 38000,
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.raw_register = ir_imon_register,
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.min_timeout = IMON_UNIT * IMON_BITS * 2,
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};
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static int __init ir_imon_decode_init(void)
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{
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ir_raw_handler_register(&imon_handler);
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pr_info("IR iMON protocol handler initialized\n");
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return 0;
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}
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static void __exit ir_imon_decode_exit(void)
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{
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ir_raw_handler_unregister(&imon_handler);
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}
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module_init(ir_imon_decode_init);
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module_exit(ir_imon_decode_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Sean Young <sean@mess.org>");
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MODULE_DESCRIPTION("iMON IR protocol decoder");
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