1 /* ir-rc6-decoder.c - A decoder for the RC6 IR protocol
3 * Copyright (C) 2010 by David Härdeman <david@hardeman.nu>
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.
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.
15 #include "ir-core-priv.h"
18 * This decoder currently supports:
19 * RC6-0-16 (standard toggle bit in header)
20 * RC6-6A-24 (no toggle bit)
21 * RC6-6A-32 (MCE version with toggle bit in body)
24 #define RC6_UNIT 444444 /* us */
25 #define RC6_HEADER_NBITS 4 /* not including toggle bit */
26 #define RC6_0_NBITS 16
27 #define RC6_6A_SMALL_NBITS 24
28 #define RC6_6A_LARGE_NBITS 32
29 #define RC6_PREFIX_PULSE (6 * RC6_UNIT)
30 #define RC6_PREFIX_SPACE (2 * RC6_UNIT)
31 #define RC6_BIT_START (1 * RC6_UNIT)
32 #define RC6_BIT_END (1 * RC6_UNIT)
33 #define RC6_TOGGLE_START (2 * RC6_UNIT)
34 #define RC6_TOGGLE_END (2 * RC6_UNIT)
35 #define RC6_MODE_MASK 0x07 /* for the header bits */
36 #define RC6_STARTBIT_MASK 0x08 /* for the header bits */
37 #define RC6_6A_MCE_TOGGLE_MASK 0x8000 /* for the body bits */
48 STATE_HEADER_BIT_START,
57 static enum rc6_mode rc6_mode(struct rc6_dec *data)
59 switch (data->header & RC6_MODE_MASK) {
67 return RC6_MODE_UNKNOWN;
72 * ir_rc6_decode() - Decode one RC6 pulse or space
73 * @input_dev: the struct input_dev descriptor of the device
74 * @ev: the struct ir_raw_event descriptor of the pulse/space
76 * This function returns -EINVAL if the pulse violates the state machine
78 static int ir_rc6_decode(struct input_dev *input_dev, struct ir_raw_event ev)
80 struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
81 struct rc6_dec *data = &ir_dev->raw->rc6;
85 if (!(ir_dev->raw->enabled_protocols & IR_TYPE_RC6))
89 data->state = STATE_INACTIVE;
93 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
97 IR_dprintk(2, "RC6 decode started at state %i (%uus %s)\n",
98 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
100 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
103 switch (data->state) {
109 /* Note: larger margin on first pulse since each RC6_UNIT
110 is quite short and some hardware takes some time to
111 adjust to the signal */
112 if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT))
115 data->state = STATE_PREFIX_SPACE;
119 case STATE_PREFIX_SPACE:
123 if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2))
126 data->state = STATE_HEADER_BIT_START;
129 case STATE_HEADER_BIT_START:
130 if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
137 data->state = STATE_HEADER_BIT_END;
140 case STATE_HEADER_BIT_END:
141 if (!is_transition(&ev, &ir_dev->raw->prev_ev))
144 if (data->count == RC6_HEADER_NBITS)
145 data->state = STATE_TOGGLE_START;
147 data->state = STATE_HEADER_BIT_START;
149 decrease_duration(&ev, RC6_BIT_END);
152 case STATE_TOGGLE_START:
153 if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2))
156 data->toggle = ev.pulse;
157 data->state = STATE_TOGGLE_END;
160 case STATE_TOGGLE_END:
161 if (!is_transition(&ev, &ir_dev->raw->prev_ev) ||
162 !geq_margin(ev.duration, RC6_TOGGLE_END, RC6_UNIT / 2))
165 if (!(data->header & RC6_STARTBIT_MASK)) {
166 IR_dprintk(1, "RC6 invalid start bit\n");
170 data->state = STATE_BODY_BIT_START;
171 decrease_duration(&ev, RC6_TOGGLE_END);
174 switch (rc6_mode(data)) {
176 data->wanted_bits = RC6_0_NBITS;
179 /* This might look weird, but we basically
180 check the value of the first body bit to
181 determine the number of bits in mode 6A */
182 if ((!ev.pulse && !geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) ||
183 geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
184 data->wanted_bits = RC6_6A_LARGE_NBITS;
186 data->wanted_bits = RC6_6A_SMALL_NBITS;
189 IR_dprintk(1, "RC6 unknown mode\n");
194 case STATE_BODY_BIT_START:
195 if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
202 data->state = STATE_BODY_BIT_END;
205 case STATE_BODY_BIT_END:
206 if (!is_transition(&ev, &ir_dev->raw->prev_ev))
209 if (data->count == data->wanted_bits)
210 data->state = STATE_FINISHED;
212 data->state = STATE_BODY_BIT_START;
214 decrease_duration(&ev, RC6_BIT_END);
221 switch (rc6_mode(data)) {
223 scancode = data->body & 0xffff;
224 toggle = data->toggle;
225 IR_dprintk(1, "RC6(0) scancode 0x%04x (toggle: %u)\n",
229 if (data->wanted_bits == RC6_6A_LARGE_NBITS) {
230 toggle = data->body & RC6_6A_MCE_TOGGLE_MASK ? 1 : 0;
231 scancode = data->body & ~RC6_6A_MCE_TOGGLE_MASK;
234 scancode = data->body & 0xffffff;
237 IR_dprintk(1, "RC6(6A) scancode 0x%08x (toggle: %u)\n",
241 IR_dprintk(1, "RC6 unknown mode\n");
245 ir_keydown(input_dev, scancode, toggle);
246 data->state = STATE_INACTIVE;
251 IR_dprintk(1, "RC6 decode failed at state %i (%uus %s)\n",
252 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
253 data->state = STATE_INACTIVE;
257 static struct ir_raw_handler rc6_handler = {
258 .protocols = IR_TYPE_RC6,
259 .decode = ir_rc6_decode,
262 static int __init ir_rc6_decode_init(void)
264 ir_raw_handler_register(&rc6_handler);
266 printk(KERN_INFO "IR RC6 protocol handler initialized\n");
270 static void __exit ir_rc6_decode_exit(void)
272 ir_raw_handler_unregister(&rc6_handler);
275 module_init(ir_rc6_decode_init);
276 module_exit(ir_rc6_decode_exit);
278 MODULE_LICENSE("GPL");
279 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
280 MODULE_DESCRIPTION("RC6 IR protocol decoder");