301 lines
7.2 KiB
C
301 lines
7.2 KiB
C
/* ir-rc6-decoder.c - A decoder for the RC6 IR protocol
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*
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* Copyright (C) 2010 by David Härdeman <david@hardeman.nu>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include "rc-core-priv.h"
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#include <linux/module.h>
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/*
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* This decoder currently supports:
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* RC6-0-16 (standard toggle bit in header)
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* RC6-6A-20 (no toggle bit)
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* RC6-6A-24 (no toggle bit)
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* RC6-6A-32 (MCE version with toggle bit in body)
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*/
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#define RC6_UNIT 444444 /* nanosecs */
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#define RC6_HEADER_NBITS 4 /* not including toggle bit */
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#define RC6_0_NBITS 16
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#define RC6_6A_32_NBITS 32
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#define RC6_6A_NBITS 128 /* Variable 8..128 */
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#define RC6_PREFIX_PULSE (6 * RC6_UNIT)
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#define RC6_PREFIX_SPACE (2 * RC6_UNIT)
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#define RC6_BIT_START (1 * RC6_UNIT)
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#define RC6_BIT_END (1 * RC6_UNIT)
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#define RC6_TOGGLE_START (2 * RC6_UNIT)
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#define RC6_TOGGLE_END (2 * RC6_UNIT)
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#define RC6_SUFFIX_SPACE (6 * RC6_UNIT)
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#define RC6_MODE_MASK 0x07 /* for the header bits */
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#define RC6_STARTBIT_MASK 0x08 /* for the header bits */
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#define RC6_6A_MCE_TOGGLE_MASK 0x8000 /* for the body bits */
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#define RC6_6A_LCC_MASK 0xffff0000 /* RC6-6A-32 long customer code mask */
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#define RC6_6A_MCE_CC 0x800f0000 /* MCE customer code */
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#ifndef CHAR_BIT
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#define CHAR_BIT 8 /* Normally in <limits.h> */
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#endif
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enum rc6_mode {
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RC6_MODE_0,
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RC6_MODE_6A,
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RC6_MODE_UNKNOWN,
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};
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enum rc6_state {
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STATE_INACTIVE,
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STATE_PREFIX_SPACE,
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STATE_HEADER_BIT_START,
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STATE_HEADER_BIT_END,
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STATE_TOGGLE_START,
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STATE_TOGGLE_END,
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STATE_BODY_BIT_START,
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STATE_BODY_BIT_END,
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STATE_FINISHED,
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};
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static enum rc6_mode rc6_mode(struct rc6_dec *data)
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{
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switch (data->header & RC6_MODE_MASK) {
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case 0:
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return RC6_MODE_0;
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case 6:
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if (!data->toggle)
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return RC6_MODE_6A;
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/* fall through */
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default:
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return RC6_MODE_UNKNOWN;
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}
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}
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/**
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* ir_rc6_decode() - Decode one RC6 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_rc6_decode(struct rc_dev *dev, struct ir_raw_event ev)
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{
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struct rc6_dec *data = &dev->raw->rc6;
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u32 scancode;
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u8 toggle;
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if (!(dev->enabled_protocols &
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(RC_BIT_RC6_0 | RC_BIT_RC6_6A_20 | RC_BIT_RC6_6A_24 |
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RC_BIT_RC6_6A_32 | RC_BIT_RC6_MCE)))
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return 0;
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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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if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
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goto out;
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again:
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IR_dprintk(2, "RC6 decode started at state %i (%uus %s)\n",
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data->state, TO_US(ev.duration), TO_STR(ev.pulse));
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if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
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return 0;
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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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break;
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/* Note: larger margin on first pulse since each RC6_UNIT
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is quite short and some hardware takes some time to
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adjust to the signal */
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if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT))
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break;
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data->state = STATE_PREFIX_SPACE;
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data->count = 0;
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return 0;
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case STATE_PREFIX_SPACE:
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if (ev.pulse)
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break;
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if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2))
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break;
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data->state = STATE_HEADER_BIT_START;
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data->header = 0;
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return 0;
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case STATE_HEADER_BIT_START:
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if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
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break;
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data->header <<= 1;
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if (ev.pulse)
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data->header |= 1;
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data->count++;
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data->state = STATE_HEADER_BIT_END;
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return 0;
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case STATE_HEADER_BIT_END:
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if (!is_transition(&ev, &dev->raw->prev_ev))
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break;
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if (data->count == RC6_HEADER_NBITS)
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data->state = STATE_TOGGLE_START;
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else
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data->state = STATE_HEADER_BIT_START;
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decrease_duration(&ev, RC6_BIT_END);
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goto again;
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case STATE_TOGGLE_START:
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if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2))
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break;
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data->toggle = ev.pulse;
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data->state = STATE_TOGGLE_END;
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return 0;
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case STATE_TOGGLE_END:
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if (!is_transition(&ev, &dev->raw->prev_ev) ||
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!geq_margin(ev.duration, RC6_TOGGLE_END, RC6_UNIT / 2))
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break;
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if (!(data->header & RC6_STARTBIT_MASK)) {
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IR_dprintk(1, "RC6 invalid start bit\n");
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break;
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}
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data->state = STATE_BODY_BIT_START;
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decrease_duration(&ev, RC6_TOGGLE_END);
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data->count = 0;
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data->body = 0;
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switch (rc6_mode(data)) {
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case RC6_MODE_0:
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data->wanted_bits = RC6_0_NBITS;
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break;
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case RC6_MODE_6A:
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data->wanted_bits = RC6_6A_NBITS;
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break;
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default:
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IR_dprintk(1, "RC6 unknown mode\n");
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goto out;
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}
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goto again;
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case STATE_BODY_BIT_START:
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if (eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) {
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/* Discard LSB's that won't fit in data->body */
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if (data->count++ < CHAR_BIT * sizeof data->body) {
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data->body <<= 1;
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if (ev.pulse)
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data->body |= 1;
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}
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data->state = STATE_BODY_BIT_END;
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return 0;
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} else if (RC6_MODE_6A == rc6_mode(data) && !ev.pulse &&
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geq_margin(ev.duration, RC6_SUFFIX_SPACE, RC6_UNIT / 2)) {
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data->state = STATE_FINISHED;
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goto again;
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}
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break;
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case STATE_BODY_BIT_END:
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if (!is_transition(&ev, &dev->raw->prev_ev))
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break;
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if (data->count == data->wanted_bits)
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data->state = STATE_FINISHED;
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else
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data->state = STATE_BODY_BIT_START;
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decrease_duration(&ev, RC6_BIT_END);
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goto again;
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case STATE_FINISHED:
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if (ev.pulse)
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break;
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switch (rc6_mode(data)) {
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case RC6_MODE_0:
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scancode = data->body;
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toggle = data->toggle;
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IR_dprintk(1, "RC6(0) scancode 0x%04x (toggle: %u)\n",
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scancode, toggle);
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break;
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case RC6_MODE_6A:
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if (data->count > CHAR_BIT * sizeof data->body) {
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IR_dprintk(1, "RC6 too many (%u) data bits\n",
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data->count);
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goto out;
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}
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scancode = data->body;
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if (data->count == RC6_6A_32_NBITS &&
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(scancode & RC6_6A_LCC_MASK) == RC6_6A_MCE_CC) {
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/* MCE RC */
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toggle = (scancode & RC6_6A_MCE_TOGGLE_MASK) ? 1 : 0;
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scancode &= ~RC6_6A_MCE_TOGGLE_MASK;
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} else {
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toggle = 0;
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}
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IR_dprintk(1, "RC6(6A) scancode 0x%08x (toggle: %u)\n",
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scancode, toggle);
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break;
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default:
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IR_dprintk(1, "RC6 unknown mode\n");
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goto out;
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}
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rc_keydown(dev, scancode, toggle);
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data->state = STATE_INACTIVE;
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return 0;
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}
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out:
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IR_dprintk(1, "RC6 decode failed at state %i (%uus %s)\n",
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data->state, TO_US(ev.duration), TO_STR(ev.pulse));
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data->state = STATE_INACTIVE;
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return -EINVAL;
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}
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static struct ir_raw_handler rc6_handler = {
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.protocols = RC_BIT_RC6_0 | RC_BIT_RC6_6A_20 |
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RC_BIT_RC6_6A_24 | RC_BIT_RC6_6A_32 |
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RC_BIT_RC6_MCE,
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.decode = ir_rc6_decode,
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};
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static int __init ir_rc6_decode_init(void)
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{
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ir_raw_handler_register(&rc6_handler);
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printk(KERN_INFO "IR RC6 protocol handler initialized\n");
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return 0;
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}
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static void __exit ir_rc6_decode_exit(void)
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{
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ir_raw_handler_unregister(&rc6_handler);
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}
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module_init(ir_rc6_decode_init);
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module_exit(ir_rc6_decode_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
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MODULE_DESCRIPTION("RC6 IR protocol decoder");
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