306 lines
8.0 KiB
C
306 lines
8.0 KiB
C
/* ir-rc5-decoder.c - decoder for RC5(x) and StreamZap protocols
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*
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* Copyright (C) 2010 by Mauro Carvalho Chehab
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* Copyright (C) 2010 by Jarod Wilson <jarod@redhat.com>
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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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/*
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* This decoder handles the 14 bit RC5 protocol, 15 bit "StreamZap" protocol
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* and 20 bit RC5x protocol.
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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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#define RC5_NBITS 14
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#define RC5_SZ_NBITS 15
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#define RC5X_NBITS 20
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#define CHECK_RC5X_NBITS 8
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#define RC5_UNIT 888888 /* ns */
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#define RC5_BIT_START (1 * RC5_UNIT)
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#define RC5_BIT_END (1 * RC5_UNIT)
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#define RC5X_SPACE (4 * RC5_UNIT)
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#define RC5_TRAILER (6 * RC5_UNIT) /* In reality, approx 100 */
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enum rc5_state {
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STATE_INACTIVE,
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STATE_BIT_START,
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STATE_BIT_END,
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STATE_CHECK_RC5X,
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STATE_FINISHED,
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};
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/**
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* ir_rc5_decode() - Decode one RC-5 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_rc5_decode(struct rc_dev *dev, struct ir_raw_event ev)
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{
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struct rc5_dec *data = &dev->raw->rc5;
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u8 toggle;
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u32 scancode;
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enum rc_type protocol;
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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, RC5_UNIT, RC5_UNIT / 2))
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goto out;
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again:
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IR_dprintk(2, "RC5(x/sz) 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, RC5_UNIT, RC5_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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data->state = STATE_BIT_START;
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data->count = 1;
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decrease_duration(&ev, RC5_BIT_START);
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goto again;
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case STATE_BIT_START:
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if (!ev.pulse && geq_margin(ev.duration, RC5_TRAILER, RC5_UNIT / 2)) {
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data->state = STATE_FINISHED;
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goto again;
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}
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if (!eq_margin(ev.duration, RC5_BIT_START, RC5_UNIT / 2))
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break;
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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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data->count++;
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data->state = STATE_BIT_END;
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return 0;
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case STATE_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 == CHECK_RC5X_NBITS)
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data->state = STATE_CHECK_RC5X;
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else
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data->state = STATE_BIT_START;
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decrease_duration(&ev, RC5_BIT_END);
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goto again;
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case STATE_CHECK_RC5X:
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if (!ev.pulse && geq_margin(ev.duration, RC5X_SPACE, RC5_UNIT / 2)) {
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data->is_rc5x = true;
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decrease_duration(&ev, RC5X_SPACE);
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} else
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data->is_rc5x = false;
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data->state = STATE_BIT_START;
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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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if (data->is_rc5x && data->count == RC5X_NBITS) {
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/* RC5X */
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u8 xdata, command, system;
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if (!(dev->enabled_protocols & RC_BIT_RC5X_20)) {
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data->state = STATE_INACTIVE;
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return 0;
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}
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xdata = (data->bits & 0x0003F) >> 0;
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command = (data->bits & 0x00FC0) >> 6;
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system = (data->bits & 0x1F000) >> 12;
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toggle = (data->bits & 0x20000) ? 1 : 0;
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command += (data->bits & 0x40000) ? 0 : 0x40;
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scancode = system << 16 | command << 8 | xdata;
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protocol = RC_TYPE_RC5X_20;
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} else if (!data->is_rc5x && data->count == RC5_NBITS) {
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/* RC5 */
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u8 command, system;
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if (!(dev->enabled_protocols & RC_BIT_RC5)) {
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data->state = STATE_INACTIVE;
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return 0;
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}
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command = (data->bits & 0x0003F) >> 0;
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system = (data->bits & 0x007C0) >> 6;
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toggle = (data->bits & 0x00800) ? 1 : 0;
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command += (data->bits & 0x01000) ? 0 : 0x40;
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scancode = system << 8 | command;
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protocol = RC_TYPE_RC5;
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} else if (!data->is_rc5x && data->count == RC5_SZ_NBITS) {
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/* RC5 StreamZap */
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u8 command, system;
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if (!(dev->enabled_protocols & RC_BIT_RC5_SZ)) {
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data->state = STATE_INACTIVE;
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return 0;
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}
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command = (data->bits & 0x0003F) >> 0;
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system = (data->bits & 0x02FC0) >> 6;
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toggle = (data->bits & 0x01000) ? 1 : 0;
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scancode = system << 6 | command;
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protocol = RC_TYPE_RC5_SZ;
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} else
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break;
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IR_dprintk(1, "RC5(x/sz) scancode 0x%06x (p: %u, t: %u)\n",
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scancode, protocol, toggle);
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rc_keydown(dev, protocol, 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, "RC5(x/sz) decode failed at state %i count %d (%uus %s)\n",
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data->state, data->count, 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 const struct ir_raw_timings_manchester ir_rc5_timings = {
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.leader = RC5_UNIT,
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.pulse_space_start = 0,
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.clock = RC5_UNIT,
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.trailer_space = RC5_UNIT * 10,
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};
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static const struct ir_raw_timings_manchester ir_rc5x_timings[2] = {
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{
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.leader = RC5_UNIT,
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.pulse_space_start = 0,
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.clock = RC5_UNIT,
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.trailer_space = RC5X_SPACE,
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},
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{
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.clock = RC5_UNIT,
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.trailer_space = RC5_UNIT * 10,
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},
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};
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static const struct ir_raw_timings_manchester ir_rc5_sz_timings = {
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.leader = RC5_UNIT,
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.pulse_space_start = 0,
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.clock = RC5_UNIT,
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.trailer_space = RC5_UNIT * 10,
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};
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/**
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* ir_rc5_encode() - Encode a scancode as a stream of raw events
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*
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* @protocol: protocol variant 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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* -EINVAL if the scancode is ambiguous or invalid.
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*/
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static int ir_rc5_encode(enum rc_type protocol, u32 scancode,
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struct ir_raw_event *events, unsigned int max)
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{
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int ret;
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struct ir_raw_event *e = events;
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unsigned int data, xdata, command, commandx, system, pre_space_data;
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/* Detect protocol and convert scancode to raw data */
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if (protocol == RC_TYPE_RC5) {
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/* decode scancode */
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command = (scancode & 0x003f) >> 0;
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commandx = (scancode & 0x0040) >> 6;
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system = (scancode & 0x1f00) >> 8;
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/* encode data */
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data = !commandx << 12 | system << 6 | command;
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/* Modulate the data */
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ret = ir_raw_gen_manchester(&e, max, &ir_rc5_timings,
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RC5_NBITS, data);
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if (ret < 0)
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return ret;
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} else if (protocol == RC_TYPE_RC5X_20) {
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/* decode scancode */
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xdata = (scancode & 0x00003f) >> 0;
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command = (scancode & 0x003f00) >> 8;
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commandx = !(scancode & 0x004000);
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system = (scancode & 0x1f0000) >> 16;
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/* encode data */
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data = commandx << 18 | system << 12 | command << 6 | xdata;
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/* Modulate the data */
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pre_space_data = data >> (RC5X_NBITS - CHECK_RC5X_NBITS);
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ret = ir_raw_gen_manchester(&e, max, &ir_rc5x_timings[0],
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CHECK_RC5X_NBITS, pre_space_data);
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if (ret < 0)
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return ret;
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ret = ir_raw_gen_manchester(&e, max - (e - events),
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&ir_rc5x_timings[1],
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RC5X_NBITS - CHECK_RC5X_NBITS,
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data);
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if (ret < 0)
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return ret;
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} else if (protocol == RC_TYPE_RC5_SZ) {
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/* RC5-SZ scancode is raw enough for Manchester as it is */
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ret = ir_raw_gen_manchester(&e, max, &ir_rc5_sz_timings,
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RC5_SZ_NBITS, scancode & 0x2fff);
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if (ret < 0)
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return ret;
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} else {
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return -EINVAL;
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}
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return e - events;
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}
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static struct ir_raw_handler rc5_handler = {
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.protocols = RC_BIT_RC5 | RC_BIT_RC5X_20 | RC_BIT_RC5_SZ,
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.decode = ir_rc5_decode,
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.encode = ir_rc5_encode,
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};
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static int __init ir_rc5_decode_init(void)
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{
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ir_raw_handler_register(&rc5_handler);
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printk(KERN_INFO "IR RC5(x/sz) protocol handler initialized\n");
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return 0;
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}
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static void __exit ir_rc5_decode_exit(void)
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{
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ir_raw_handler_unregister(&rc5_handler);
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}
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module_init(ir_rc5_decode_init);
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module_exit(ir_rc5_decode_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Mauro Carvalho Chehab and Jarod Wilson");
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MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
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MODULE_DESCRIPTION("RC5(x/sz) IR protocol decoder");
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