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David Härdeman733419b2010-04-08 20:04:30 -03001/* ir-rc5-decoder.c - handle RC5(x) IR Pulse/Space protocol
Mauro Carvalho Chehabdb1423a2010-04-04 10:27:20 -03002 *
3 * Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation version 2 of the License.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 */
14
15/*
David Härdeman733419b2010-04-08 20:04:30 -030016 * This code handles 14 bits RC5 protocols and 20 bits RC5x protocols.
17 * There are other variants that use a different number of bits.
18 * This is currently unsupported.
19 * It considers a carrier of 36 kHz, with a total of 14/20 bits, where
Mauro Carvalho Chehab9b09df52010-04-06 02:29:42 -030020 * the first two bits are start bits, and a third one is a filing bit
Mauro Carvalho Chehabdb1423a2010-04-04 10:27:20 -030021 */
22
Mauro Carvalho Chehabf62de672010-11-09 23:09:57 -030023#include "rc-core-priv.h"
Paul Gortmaker7a707b82011-07-03 14:03:12 -040024#include <linux/module.h>
Mauro Carvalho Chehabdb1423a2010-04-04 10:27:20 -030025
26#define RC5_NBITS 14
David Härdeman733419b2010-04-08 20:04:30 -030027#define RC5X_NBITS 20
28#define CHECK_RC5X_NBITS 8
David Härdeman724e2492010-04-08 13:10:00 -030029#define RC5_UNIT 888888 /* ns */
David Härdemane40b1122010-04-15 18:46:00 -030030#define RC5_BIT_START (1 * RC5_UNIT)
31#define RC5_BIT_END (1 * RC5_UNIT)
32#define RC5X_SPACE (4 * RC5_UNIT)
Mauro Carvalho Chehabdb1423a2010-04-04 10:27:20 -030033
Mauro Carvalho Chehabdb1423a2010-04-04 10:27:20 -030034enum rc5_state {
35 STATE_INACTIVE,
David Härdeman724e2492010-04-08 13:10:00 -030036 STATE_BIT_START,
37 STATE_BIT_END,
David Härdeman733419b2010-04-08 20:04:30 -030038 STATE_CHECK_RC5X,
David Härdeman724e2492010-04-08 13:10:00 -030039 STATE_FINISHED,
Mauro Carvalho Chehabdb1423a2010-04-04 10:27:20 -030040};
41
Mauro Carvalho Chehabdb1423a2010-04-04 10:27:20 -030042/**
David Härdeman724e2492010-04-08 13:10:00 -030043 * ir_rc5_decode() - Decode one RC-5 pulse or space
David Härdemand8b4b582010-10-29 16:08:23 -030044 * @dev: the struct rc_dev descriptor of the device
David Härdemane40b1122010-04-15 18:46:00 -030045 * @ev: the struct ir_raw_event descriptor of the pulse/space
Mauro Carvalho Chehabdb1423a2010-04-04 10:27:20 -030046 *
47 * This function returns -EINVAL if the pulse violates the state machine
48 */
David Härdemand8b4b582010-10-29 16:08:23 -030049static int ir_rc5_decode(struct rc_dev *dev, struct ir_raw_event ev)
Mauro Carvalho Chehabdb1423a2010-04-04 10:27:20 -030050{
David Härdemand8b4b582010-10-29 16:08:23 -030051 struct rc5_dec *data = &dev->raw->rc5;
David Härdeman733419b2010-04-08 20:04:30 -030052 u8 toggle;
David Härdeman724e2492010-04-08 13:10:00 -030053 u32 scancode;
Mauro Carvalho Chehabdb1423a2010-04-04 10:27:20 -030054
Mauro Carvalho Chehab52b66142010-11-17 14:20:52 -030055 if (!(dev->raw->enabled_protocols & RC_TYPE_RC5))
David Härdeman667c9eb2010-06-13 17:29:31 -030056 return 0;
Mauro Carvalho Chehab7f20d322010-04-04 14:45:04 -030057
Maxim Levitsky46519182010-10-16 19:56:28 -030058 if (!is_timing_event(ev)) {
59 if (ev.reset)
60 data->state = STATE_INACTIVE;
Mauro Carvalho Chehabdb1423a2010-04-04 10:27:20 -030061 return 0;
62 }
63
David Härdemane40b1122010-04-15 18:46:00 -030064 if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
David Härdeman724e2492010-04-08 13:10:00 -030065 goto out;
66
67again:
David Härdemane40b1122010-04-15 18:46:00 -030068 IR_dprintk(2, "RC5(x) decode started at state %i (%uus %s)\n",
69 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
David Härdeman724e2492010-04-08 13:10:00 -030070
David Härdemane40b1122010-04-15 18:46:00 -030071 if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
David Härdeman724e2492010-04-08 13:10:00 -030072 return 0;
73
74 switch (data->state) {
75
76 case STATE_INACTIVE:
David Härdemane40b1122010-04-15 18:46:00 -030077 if (!ev.pulse)
78 break;
79
80 data->state = STATE_BIT_START;
81 data->count = 1;
82 /* We just need enough bits to get to STATE_CHECK_RC5X */
83 data->wanted_bits = RC5X_NBITS;
84 decrease_duration(&ev, RC5_BIT_START);
85 goto again;
David Härdeman724e2492010-04-08 13:10:00 -030086
87 case STATE_BIT_START:
David Härdemane40b1122010-04-15 18:46:00 -030088 if (!eq_margin(ev.duration, RC5_BIT_START, RC5_UNIT / 2))
89 break;
David Härdeman724e2492010-04-08 13:10:00 -030090
David Härdemanc2163692010-06-13 17:29:36 -030091 data->bits <<= 1;
David Härdemane40b1122010-04-15 18:46:00 -030092 if (!ev.pulse)
David Härdemanc2163692010-06-13 17:29:36 -030093 data->bits |= 1;
David Härdemane40b1122010-04-15 18:46:00 -030094 data->count++;
David Härdemane40b1122010-04-15 18:46:00 -030095 data->state = STATE_BIT_END;
96 return 0;
David Härdeman724e2492010-04-08 13:10:00 -030097
98 case STATE_BIT_END:
David Härdemand8b4b582010-10-29 16:08:23 -030099 if (!is_transition(&ev, &dev->raw->prev_ev))
David Härdemane40b1122010-04-15 18:46:00 -0300100 break;
David Härdeman724e2492010-04-08 13:10:00 -0300101
David Härdemane40b1122010-04-15 18:46:00 -0300102 if (data->count == data->wanted_bits)
103 data->state = STATE_FINISHED;
104 else if (data->count == CHECK_RC5X_NBITS)
105 data->state = STATE_CHECK_RC5X;
106 else
107 data->state = STATE_BIT_START;
108
109 decrease_duration(&ev, RC5_BIT_END);
110 goto again;
David Härdeman724e2492010-04-08 13:10:00 -0300111
David Härdeman733419b2010-04-08 20:04:30 -0300112 case STATE_CHECK_RC5X:
David Härdemane40b1122010-04-15 18:46:00 -0300113 if (!ev.pulse && geq_margin(ev.duration, RC5X_SPACE, RC5_UNIT / 2)) {
David Härdeman733419b2010-04-08 20:04:30 -0300114 /* RC5X */
115 data->wanted_bits = RC5X_NBITS;
David Härdemane40b1122010-04-15 18:46:00 -0300116 decrease_duration(&ev, RC5X_SPACE);
David Härdeman733419b2010-04-08 20:04:30 -0300117 } else {
118 /* RC5 */
119 data->wanted_bits = RC5_NBITS;
120 }
121 data->state = STATE_BIT_START;
122 goto again;
David Härdeman724e2492010-04-08 13:10:00 -0300123
David Härdeman733419b2010-04-08 20:04:30 -0300124 case STATE_FINISHED:
David Härdemane40b1122010-04-15 18:46:00 -0300125 if (ev.pulse)
126 break;
127
David Härdeman733419b2010-04-08 20:04:30 -0300128 if (data->wanted_bits == RC5X_NBITS) {
129 /* RC5X */
130 u8 xdata, command, system;
David Härdemanc2163692010-06-13 17:29:36 -0300131 xdata = (data->bits & 0x0003F) >> 0;
132 command = (data->bits & 0x00FC0) >> 6;
133 system = (data->bits & 0x1F000) >> 12;
134 toggle = (data->bits & 0x20000) ? 1 : 0;
135 command += (data->bits & 0x01000) ? 0 : 0x40;
David Härdeman733419b2010-04-08 20:04:30 -0300136 scancode = system << 16 | command << 8 | xdata;
137
138 IR_dprintk(1, "RC5X scancode 0x%06x (toggle: %u)\n",
139 scancode, toggle);
140
141 } else {
142 /* RC5 */
143 u8 command, system;
David Härdemanc2163692010-06-13 17:29:36 -0300144 command = (data->bits & 0x0003F) >> 0;
145 system = (data->bits & 0x007C0) >> 6;
146 toggle = (data->bits & 0x00800) ? 1 : 0;
147 command += (data->bits & 0x01000) ? 0 : 0x40;
David Härdeman733419b2010-04-08 20:04:30 -0300148 scancode = system << 8 | command;
149
150 IR_dprintk(1, "RC5 scancode 0x%04x (toggle: %u)\n",
151 scancode, toggle);
152 }
153
Mauro Carvalho Chehabca866742010-11-17 13:53:11 -0300154 rc_keydown(dev, scancode, toggle);
David Härdeman724e2492010-04-08 13:10:00 -0300155 data->state = STATE_INACTIVE;
156 return 0;
157 }
158
159out:
David Härdemane40b1122010-04-15 18:46:00 -0300160 IR_dprintk(1, "RC5(x) decode failed at state %i (%uus %s)\n",
161 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
Mauro Carvalho Chehabdb1423a2010-04-04 10:27:20 -0300162 data->state = STATE_INACTIVE;
163 return -EINVAL;
164}
165
Mauro Carvalho Chehabdb1423a2010-04-04 10:27:20 -0300166static struct ir_raw_handler rc5_handler = {
Mauro Carvalho Chehab52b66142010-11-17 14:20:52 -0300167 .protocols = RC_TYPE_RC5,
Mauro Carvalho Chehabdb1423a2010-04-04 10:27:20 -0300168 .decode = ir_rc5_decode,
Mauro Carvalho Chehabdb1423a2010-04-04 10:27:20 -0300169};
170
171static int __init ir_rc5_decode_init(void)
172{
173 ir_raw_handler_register(&rc5_handler);
174
David Härdeman733419b2010-04-08 20:04:30 -0300175 printk(KERN_INFO "IR RC5(x) protocol handler initialized\n");
Mauro Carvalho Chehabdb1423a2010-04-04 10:27:20 -0300176 return 0;
177}
178
179static void __exit ir_rc5_decode_exit(void)
180{
181 ir_raw_handler_unregister(&rc5_handler);
182}
183
184module_init(ir_rc5_decode_init);
185module_exit(ir_rc5_decode_exit);
186
187MODULE_LICENSE("GPL");
188MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@redhat.com>");
189MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
David Härdeman733419b2010-04-08 20:04:30 -0300190MODULE_DESCRIPTION("RC5(x) IR protocol decoder");