1 /* ir-rc6-decoder.c - A decoder for the RC6 IR protocol
2 *
3 * Copyright (C) 2010 by David Härdeman <david@hardeman.nu>
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 #include "rc-core-priv.h"
16 #include <linux/module.h>
17
18 /*
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)
24 */
25
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 */
43 #define RC6_6A_KATHREIN_CC 0x80460000 /* Kathrein RCU-676 customer code */
44 #ifndef CHAR_BIT
45 #define CHAR_BIT 8 /* Normally in <limits.h> */
46 #endif
47
48 enum rc6_mode {
49 RC6_MODE_0,
50 RC6_MODE_6A,
51 RC6_MODE_UNKNOWN,
52 };
53
54 enum rc6_state {
55 STATE_INACTIVE,
56 STATE_PREFIX_SPACE,
57 STATE_HEADER_BIT_START,
58 STATE_HEADER_BIT_END,
59 STATE_TOGGLE_START,
60 STATE_TOGGLE_END,
61 STATE_BODY_BIT_START,
62 STATE_BODY_BIT_END,
63 STATE_FINISHED,
64 };
65
rc6_mode(struct rc6_dec * data)66 static enum rc6_mode rc6_mode(struct rc6_dec *data)
67 {
68 switch (data->header & RC6_MODE_MASK) {
69 case 0:
70 return RC6_MODE_0;
71 case 6:
72 if (!data->toggle)
73 return RC6_MODE_6A;
74 /* fall through */
75 default:
76 return RC6_MODE_UNKNOWN;
77 }
78 }
79
80 /**
81 * ir_rc6_decode() - Decode one RC6 pulse or space
82 * @dev: the struct rc_dev descriptor of the device
83 * @ev: the struct ir_raw_event descriptor of the pulse/space
84 *
85 * This function returns -EINVAL if the pulse violates the state machine
86 */
ir_rc6_decode(struct rc_dev * dev,struct ir_raw_event ev)87 static int ir_rc6_decode(struct rc_dev *dev, struct ir_raw_event ev)
88 {
89 struct rc6_dec *data = &dev->raw->rc6;
90 u32 scancode;
91 u8 toggle;
92 enum rc_proto protocol;
93
94 if (!is_timing_event(ev)) {
95 if (ev.reset)
96 data->state = STATE_INACTIVE;
97 return 0;
98 }
99
100 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
101 goto out;
102
103 again:
104 IR_dprintk(2, "RC6 decode started at state %i (%uus %s)\n",
105 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
106
107 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
108 return 0;
109
110 switch (data->state) {
111
112 case STATE_INACTIVE:
113 if (!ev.pulse)
114 break;
115
116 /* Note: larger margin on first pulse since each RC6_UNIT
117 is quite short and some hardware takes some time to
118 adjust to the signal */
119 if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT))
120 break;
121
122 data->state = STATE_PREFIX_SPACE;
123 data->count = 0;
124 return 0;
125
126 case STATE_PREFIX_SPACE:
127 if (ev.pulse)
128 break;
129
130 if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2))
131 break;
132
133 data->state = STATE_HEADER_BIT_START;
134 data->header = 0;
135 return 0;
136
137 case STATE_HEADER_BIT_START:
138 if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
139 break;
140
141 data->header <<= 1;
142 if (ev.pulse)
143 data->header |= 1;
144 data->count++;
145 data->state = STATE_HEADER_BIT_END;
146 return 0;
147
148 case STATE_HEADER_BIT_END:
149 if (!is_transition(&ev, &dev->raw->prev_ev))
150 break;
151
152 if (data->count == RC6_HEADER_NBITS)
153 data->state = STATE_TOGGLE_START;
154 else
155 data->state = STATE_HEADER_BIT_START;
156
157 decrease_duration(&ev, RC6_BIT_END);
158 goto again;
159
160 case STATE_TOGGLE_START:
161 if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2))
162 break;
163
164 data->toggle = ev.pulse;
165 data->state = STATE_TOGGLE_END;
166 return 0;
167
168 case STATE_TOGGLE_END:
169 if (!is_transition(&ev, &dev->raw->prev_ev) ||
170 !geq_margin(ev.duration, RC6_TOGGLE_END, RC6_UNIT / 2))
171 break;
172
173 if (!(data->header & RC6_STARTBIT_MASK)) {
174 IR_dprintk(1, "RC6 invalid start bit\n");
175 break;
176 }
177
178 data->state = STATE_BODY_BIT_START;
179 decrease_duration(&ev, RC6_TOGGLE_END);
180 data->count = 0;
181 data->body = 0;
182
183 switch (rc6_mode(data)) {
184 case RC6_MODE_0:
185 data->wanted_bits = RC6_0_NBITS;
186 break;
187 case RC6_MODE_6A:
188 data->wanted_bits = RC6_6A_NBITS;
189 break;
190 default:
191 IR_dprintk(1, "RC6 unknown mode\n");
192 goto out;
193 }
194 goto again;
195
196 case STATE_BODY_BIT_START:
197 if (eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) {
198 /* Discard LSB's that won't fit in data->body */
199 if (data->count++ < CHAR_BIT * sizeof data->body) {
200 data->body <<= 1;
201 if (ev.pulse)
202 data->body |= 1;
203 }
204 data->state = STATE_BODY_BIT_END;
205 return 0;
206 } else if (RC6_MODE_6A == rc6_mode(data) && !ev.pulse &&
207 geq_margin(ev.duration, RC6_SUFFIX_SPACE, RC6_UNIT / 2)) {
208 data->state = STATE_FINISHED;
209 goto again;
210 }
211 break;
212
213 case STATE_BODY_BIT_END:
214 if (!is_transition(&ev, &dev->raw->prev_ev))
215 break;
216
217 if (data->count == data->wanted_bits)
218 data->state = STATE_FINISHED;
219 else
220 data->state = STATE_BODY_BIT_START;
221
222 decrease_duration(&ev, RC6_BIT_END);
223 goto again;
224
225 case STATE_FINISHED:
226 if (ev.pulse)
227 break;
228
229 switch (rc6_mode(data)) {
230 case RC6_MODE_0:
231 scancode = data->body;
232 toggle = data->toggle;
233 protocol = RC_PROTO_RC6_0;
234 IR_dprintk(1, "RC6(0) scancode 0x%04x (toggle: %u)\n",
235 scancode, toggle);
236 break;
237
238 case RC6_MODE_6A:
239 if (data->count > CHAR_BIT * sizeof data->body) {
240 IR_dprintk(1, "RC6 too many (%u) data bits\n",
241 data->count);
242 goto out;
243 }
244
245 scancode = data->body;
246 switch (data->count) {
247 case 20:
248 protocol = RC_PROTO_RC6_6A_20;
249 toggle = 0;
250 break;
251 case 24:
252 protocol = RC_PROTO_RC6_6A_24;
253 toggle = 0;
254 break;
255 case 32:
256 switch (scancode & RC6_6A_LCC_MASK) {
257 case RC6_6A_MCE_CC:
258 case RC6_6A_KATHREIN_CC:
259 protocol = RC_PROTO_RC6_MCE;
260 toggle = !!(scancode & RC6_6A_MCE_TOGGLE_MASK);
261 scancode &= ~RC6_6A_MCE_TOGGLE_MASK;
262 break;
263 default:
264 protocol = RC_PROTO_RC6_6A_32;
265 toggle = 0;
266 break;
267 }
268 break;
269 default:
270 IR_dprintk(1, "RC6(6A) unsupported length\n");
271 goto out;
272 }
273
274 IR_dprintk(1, "RC6(6A) proto 0x%04x, scancode 0x%08x (toggle: %u)\n",
275 protocol, scancode, toggle);
276 break;
277 default:
278 IR_dprintk(1, "RC6 unknown mode\n");
279 goto out;
280 }
281
282 rc_keydown(dev, protocol, scancode, toggle);
283 data->state = STATE_INACTIVE;
284 return 0;
285 }
286
287 out:
288 IR_dprintk(1, "RC6 decode failed at state %i (%uus %s)\n",
289 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
290 data->state = STATE_INACTIVE;
291 return -EINVAL;
292 }
293
294 static const struct ir_raw_timings_manchester ir_rc6_timings[4] = {
295 {
296 .leader = RC6_PREFIX_PULSE,
297 .pulse_space_start = 0,
298 .clock = RC6_UNIT,
299 .invert = 1,
300 .trailer_space = RC6_PREFIX_SPACE,
301 },
302 {
303 .clock = RC6_UNIT,
304 .invert = 1,
305 },
306 {
307 .clock = RC6_UNIT * 2,
308 .invert = 1,
309 },
310 {
311 .clock = RC6_UNIT,
312 .invert = 1,
313 .trailer_space = RC6_SUFFIX_SPACE,
314 },
315 };
316
317 /**
318 * ir_rc6_encode() - Encode a scancode as a stream of raw events
319 *
320 * @protocol: protocol to encode
321 * @scancode: scancode to encode
322 * @events: array of raw ir events to write into
323 * @max: maximum size of @events
324 *
325 * Returns: The number of events written.
326 * -ENOBUFS if there isn't enough space in the array to fit the
327 * encoding. In this case all @max events will have been written.
328 * -EINVAL if the scancode is ambiguous or invalid.
329 */
ir_rc6_encode(enum rc_proto protocol,u32 scancode,struct ir_raw_event * events,unsigned int max)330 static int ir_rc6_encode(enum rc_proto protocol, u32 scancode,
331 struct ir_raw_event *events, unsigned int max)
332 {
333 int ret;
334 struct ir_raw_event *e = events;
335
336 if (protocol == RC_PROTO_RC6_0) {
337 /* Modulate the preamble */
338 ret = ir_raw_gen_manchester(&e, max, &ir_rc6_timings[0], 0, 0);
339 if (ret < 0)
340 return ret;
341
342 /* Modulate the header (Start Bit & Mode-0) */
343 ret = ir_raw_gen_manchester(&e, max - (e - events),
344 &ir_rc6_timings[1],
345 RC6_HEADER_NBITS, (1 << 3));
346 if (ret < 0)
347 return ret;
348
349 /* Modulate Trailer Bit */
350 ret = ir_raw_gen_manchester(&e, max - (e - events),
351 &ir_rc6_timings[2], 1, 0);
352 if (ret < 0)
353 return ret;
354
355 /* Modulate rest of the data */
356 ret = ir_raw_gen_manchester(&e, max - (e - events),
357 &ir_rc6_timings[3], RC6_0_NBITS,
358 scancode);
359 if (ret < 0)
360 return ret;
361
362 } else {
363 int bits;
364
365 switch (protocol) {
366 case RC_PROTO_RC6_MCE:
367 case RC_PROTO_RC6_6A_32:
368 bits = 32;
369 break;
370 case RC_PROTO_RC6_6A_24:
371 bits = 24;
372 break;
373 case RC_PROTO_RC6_6A_20:
374 bits = 20;
375 break;
376 default:
377 return -EINVAL;
378 }
379
380 /* Modulate the preamble */
381 ret = ir_raw_gen_manchester(&e, max, &ir_rc6_timings[0], 0, 0);
382 if (ret < 0)
383 return ret;
384
385 /* Modulate the header (Start Bit & Header-version 6 */
386 ret = ir_raw_gen_manchester(&e, max - (e - events),
387 &ir_rc6_timings[1],
388 RC6_HEADER_NBITS, (1 << 3 | 6));
389 if (ret < 0)
390 return ret;
391
392 /* Modulate Trailer Bit */
393 ret = ir_raw_gen_manchester(&e, max - (e - events),
394 &ir_rc6_timings[2], 1, 0);
395 if (ret < 0)
396 return ret;
397
398 /* Modulate rest of the data */
399 ret = ir_raw_gen_manchester(&e, max - (e - events),
400 &ir_rc6_timings[3],
401 bits,
402 scancode);
403 if (ret < 0)
404 return ret;
405 }
406
407 return e - events;
408 }
409
410 static struct ir_raw_handler rc6_handler = {
411 .protocols = RC_PROTO_BIT_RC6_0 | RC_PROTO_BIT_RC6_6A_20 |
412 RC_PROTO_BIT_RC6_6A_24 | RC_PROTO_BIT_RC6_6A_32 |
413 RC_PROTO_BIT_RC6_MCE,
414 .decode = ir_rc6_decode,
415 .encode = ir_rc6_encode,
416 };
417
ir_rc6_decode_init(void)418 static int __init ir_rc6_decode_init(void)
419 {
420 ir_raw_handler_register(&rc6_handler);
421
422 printk(KERN_INFO "IR RC6 protocol handler initialized\n");
423 return 0;
424 }
425
ir_rc6_decode_exit(void)426 static void __exit ir_rc6_decode_exit(void)
427 {
428 ir_raw_handler_unregister(&rc6_handler);
429 }
430
431 module_init(ir_rc6_decode_init);
432 module_exit(ir_rc6_decode_exit);
433
434 MODULE_LICENSE("GPL");
435 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
436 MODULE_DESCRIPTION("RC6 IR protocol decoder");
437