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 "rc-core-priv.h"
16 #include <linux/module.h>
19 * This decoder currently supports:
20 * RC6-0-16 (standard toggle bit in header)
21 * RC6-6A-20 (no toggle bit)
22 * RC6-6A-24 (no toggle bit)
23 * RC6-6A-32 (MCE version with toggle bit in body)
26 #define RC6_UNIT 444444 /* nanosecs */
27 #define RC6_HEADER_NBITS 4 /* not including toggle bit */
28 #define RC6_0_NBITS 16
29 #define RC6_6A_32_NBITS 32
30 #define RC6_6A_NBITS 128 /* Variable 8..128 */
31 #define RC6_PREFIX_PULSE (6 * RC6_UNIT)
32 #define RC6_PREFIX_SPACE (2 * RC6_UNIT)
33 #define RC6_BIT_START (1 * RC6_UNIT)
34 #define RC6_BIT_END (1 * RC6_UNIT)
35 #define RC6_TOGGLE_START (2 * RC6_UNIT)
36 #define RC6_TOGGLE_END (2 * RC6_UNIT)
37 #define RC6_SUFFIX_SPACE (6 * RC6_UNIT)
38 #define RC6_MODE_MASK 0x07 /* for the header bits */
39 #define RC6_STARTBIT_MASK 0x08 /* for the header bits */
40 #define RC6_6A_MCE_TOGGLE_MASK 0x8000 /* for the body bits */
41 #define RC6_6A_LCC_MASK 0xffff0000 /* RC6-6A-32 long customer code mask */
42 #define RC6_6A_MCE_CC 0x800f0000 /* MCE customer code */
44 #define CHAR_BIT 8 /* Normally in <limits.h> */
56 STATE_HEADER_BIT_START,
65 static enum rc6_mode rc6_mode(struct rc6_dec *data)
67 switch (data->header & RC6_MODE_MASK) {
75 return RC6_MODE_UNKNOWN;
80 * ir_rc6_decode() - Decode one RC6 pulse or space
81 * @dev: the struct rc_dev descriptor of the device
82 * @ev: the struct ir_raw_event descriptor of the pulse/space
84 * This function returns -EINVAL if the pulse violates the state machine
86 static int ir_rc6_decode(struct rc_dev *dev, struct ir_raw_event ev)
88 struct rc6_dec *data = &dev->raw->rc6;
91 enum rc_proto protocol;
93 if (!is_timing_event(ev)) {
95 data->state = STATE_INACTIVE;
99 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
103 IR_dprintk(2, "RC6 decode started at state %i (%uus %s)\n",
104 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
106 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
109 switch (data->state) {
115 /* Note: larger margin on first pulse since each RC6_UNIT
116 is quite short and some hardware takes some time to
117 adjust to the signal */
118 if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT))
121 data->state = STATE_PREFIX_SPACE;
125 case STATE_PREFIX_SPACE:
129 if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2))
132 data->state = STATE_HEADER_BIT_START;
136 case STATE_HEADER_BIT_START:
137 if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
144 data->state = STATE_HEADER_BIT_END;
147 case STATE_HEADER_BIT_END:
148 if (!is_transition(&ev, &dev->raw->prev_ev))
151 if (data->count == RC6_HEADER_NBITS)
152 data->state = STATE_TOGGLE_START;
154 data->state = STATE_HEADER_BIT_START;
156 decrease_duration(&ev, RC6_BIT_END);
159 case STATE_TOGGLE_START:
160 if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2))
163 data->toggle = ev.pulse;
164 data->state = STATE_TOGGLE_END;
167 case STATE_TOGGLE_END:
168 if (!is_transition(&ev, &dev->raw->prev_ev) ||
169 !geq_margin(ev.duration, RC6_TOGGLE_END, RC6_UNIT / 2))
172 if (!(data->header & RC6_STARTBIT_MASK)) {
173 IR_dprintk(1, "RC6 invalid start bit\n");
177 data->state = STATE_BODY_BIT_START;
178 decrease_duration(&ev, RC6_TOGGLE_END);
182 switch (rc6_mode(data)) {
184 data->wanted_bits = RC6_0_NBITS;
187 data->wanted_bits = RC6_6A_NBITS;
190 IR_dprintk(1, "RC6 unknown mode\n");
195 case STATE_BODY_BIT_START:
196 if (eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) {
197 /* Discard LSB's that won't fit in data->body */
198 if (data->count++ < CHAR_BIT * sizeof data->body) {
203 data->state = STATE_BODY_BIT_END;
205 } else if (RC6_MODE_6A == rc6_mode(data) && !ev.pulse &&
206 geq_margin(ev.duration, RC6_SUFFIX_SPACE, RC6_UNIT / 2)) {
207 data->state = STATE_FINISHED;
212 case STATE_BODY_BIT_END:
213 if (!is_transition(&ev, &dev->raw->prev_ev))
216 if (data->count == data->wanted_bits)
217 data->state = STATE_FINISHED;
219 data->state = STATE_BODY_BIT_START;
221 decrease_duration(&ev, RC6_BIT_END);
228 switch (rc6_mode(data)) {
230 scancode = data->body;
231 toggle = data->toggle;
232 protocol = RC_PROTO_RC6_0;
233 IR_dprintk(1, "RC6(0) scancode 0x%04x (toggle: %u)\n",
238 if (data->count > CHAR_BIT * sizeof data->body) {
239 IR_dprintk(1, "RC6 too many (%u) data bits\n",
244 scancode = data->body;
245 switch (data->count) {
247 protocol = RC_PROTO_RC6_6A_20;
251 protocol = RC_PROTO_RC6_6A_24;
255 if ((scancode & RC6_6A_LCC_MASK) == RC6_6A_MCE_CC) {
256 protocol = RC_PROTO_RC6_MCE;
257 toggle = !!(scancode & RC6_6A_MCE_TOGGLE_MASK);
258 scancode &= ~RC6_6A_MCE_TOGGLE_MASK;
260 protocol = RC_PROTO_RC6_6A_32;
265 IR_dprintk(1, "RC6(6A) unsupported length\n");
269 IR_dprintk(1, "RC6(6A) proto 0x%04x, scancode 0x%08x (toggle: %u)\n",
270 protocol, scancode, toggle);
273 IR_dprintk(1, "RC6 unknown mode\n");
277 rc_keydown(dev, protocol, scancode, toggle);
278 data->state = STATE_INACTIVE;
283 IR_dprintk(1, "RC6 decode failed at state %i (%uus %s)\n",
284 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
285 data->state = STATE_INACTIVE;
289 static const struct ir_raw_timings_manchester ir_rc6_timings[4] = {
291 .leader = RC6_PREFIX_PULSE,
292 .pulse_space_start = 0,
295 .trailer_space = RC6_PREFIX_SPACE,
302 .clock = RC6_UNIT * 2,
308 .trailer_space = RC6_SUFFIX_SPACE,
313 * ir_rc6_encode() - Encode a scancode as a stream of raw events
315 * @protocol: protocol to encode
316 * @scancode: scancode to encode
317 * @events: array of raw ir events to write into
318 * @max: maximum size of @events
320 * Returns: The number of events written.
321 * -ENOBUFS if there isn't enough space in the array to fit the
322 * encoding. In this case all @max events will have been written.
323 * -EINVAL if the scancode is ambiguous or invalid.
325 static int ir_rc6_encode(enum rc_proto protocol, u32 scancode,
326 struct ir_raw_event *events, unsigned int max)
329 struct ir_raw_event *e = events;
331 if (protocol == RC_PROTO_RC6_0) {
332 /* Modulate the preamble */
333 ret = ir_raw_gen_manchester(&e, max, &ir_rc6_timings[0], 0, 0);
337 /* Modulate the header (Start Bit & Mode-0) */
338 ret = ir_raw_gen_manchester(&e, max - (e - events),
340 RC6_HEADER_NBITS, (1 << 3));
344 /* Modulate Trailer Bit */
345 ret = ir_raw_gen_manchester(&e, max - (e - events),
346 &ir_rc6_timings[2], 1, 0);
350 /* Modulate rest of the data */
351 ret = ir_raw_gen_manchester(&e, max - (e - events),
352 &ir_rc6_timings[3], RC6_0_NBITS,
361 case RC_PROTO_RC6_MCE:
362 case RC_PROTO_RC6_6A_32:
365 case RC_PROTO_RC6_6A_24:
368 case RC_PROTO_RC6_6A_20:
375 /* Modulate the preamble */
376 ret = ir_raw_gen_manchester(&e, max, &ir_rc6_timings[0], 0, 0);
380 /* Modulate the header (Start Bit & Header-version 6 */
381 ret = ir_raw_gen_manchester(&e, max - (e - events),
383 RC6_HEADER_NBITS, (1 << 3 | 6));
387 /* Modulate Trailer Bit */
388 ret = ir_raw_gen_manchester(&e, max - (e - events),
389 &ir_rc6_timings[2], 1, 0);
393 /* Modulate rest of the data */
394 ret = ir_raw_gen_manchester(&e, max - (e - events),
405 static struct ir_raw_handler rc6_handler = {
406 .protocols = RC_PROTO_BIT_RC6_0 | RC_PROTO_BIT_RC6_6A_20 |
407 RC_PROTO_BIT_RC6_6A_24 | RC_PROTO_BIT_RC6_6A_32 |
408 RC_PROTO_BIT_RC6_MCE,
409 .decode = ir_rc6_decode,
410 .encode = ir_rc6_encode,
413 static int __init ir_rc6_decode_init(void)
415 ir_raw_handler_register(&rc6_handler);
417 printk(KERN_INFO "IR RC6 protocol handler initialized\n");
421 static void __exit ir_rc6_decode_exit(void)
423 ir_raw_handler_unregister(&rc6_handler);
426 module_init(ir_rc6_decode_init);
427 module_exit(ir_rc6_decode_exit);
429 MODULE_LICENSE("GPL");
430 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
431 MODULE_DESCRIPTION("RC6 IR protocol decoder");