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 dev_dbg(&dev->dev, "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 (data->count == RC6_HEADER_NBITS)
150 data->state = STATE_TOGGLE_START;
151 else
152 data->state = STATE_HEADER_BIT_START;
153
154 decrease_duration(&ev, RC6_BIT_END);
155 goto again;
156
157 case STATE_TOGGLE_START:
158 if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2))
159 break;
160
161 data->toggle = ev.pulse;
162 data->state = STATE_TOGGLE_END;
163 return 0;
164
165 case STATE_TOGGLE_END:
166 if (!(data->header & RC6_STARTBIT_MASK)) {
167 dev_dbg(&dev->dev, "RC6 invalid start bit\n");
168 break;
169 }
170
171 data->state = STATE_BODY_BIT_START;
172 decrease_duration(&ev, RC6_TOGGLE_END);
173 data->count = 0;
174 data->body = 0;
175
176 switch (rc6_mode(data)) {
177 case RC6_MODE_0:
178 data->wanted_bits = RC6_0_NBITS;
179 break;
180 case RC6_MODE_6A:
181 data->wanted_bits = RC6_6A_NBITS;
182 break;
183 default:
184 dev_dbg(&dev->dev, "RC6 unknown mode\n");
185 goto out;
186 }
187 goto again;
188
189 case STATE_BODY_BIT_START:
190 if (eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) {
191 /* Discard LSB's that won't fit in data->body */
192 if (data->count++ < CHAR_BIT * sizeof data->body) {
193 data->body <<= 1;
194 if (ev.pulse)
195 data->body |= 1;
196 }
197 data->state = STATE_BODY_BIT_END;
198 return 0;
199 } else if (RC6_MODE_6A == rc6_mode(data) && !ev.pulse &&
200 geq_margin(ev.duration, RC6_SUFFIX_SPACE, RC6_UNIT / 2)) {
201 data->state = STATE_FINISHED;
202 goto again;
203 }
204 break;
205
206 case STATE_BODY_BIT_END:
207 if (data->count == data->wanted_bits)
208 data->state = STATE_FINISHED;
209 else
210 data->state = STATE_BODY_BIT_START;
211
212 decrease_duration(&ev, RC6_BIT_END);
213 goto again;
214
215 case STATE_FINISHED:
216 if (ev.pulse)
217 break;
218
219 switch (rc6_mode(data)) {
220 case RC6_MODE_0:
221 scancode = data->body;
222 toggle = data->toggle;
223 protocol = RC_PROTO_RC6_0;
224 dev_dbg(&dev->dev, "RC6(0) scancode 0x%04x (toggle: %u)\n",
225 scancode, toggle);
226 break;
227
228 case RC6_MODE_6A:
229 if (data->count > CHAR_BIT * sizeof data->body) {
230 dev_dbg(&dev->dev, "RC6 too many (%u) data bits\n",
231 data->count);
232 goto out;
233 }
234
235 scancode = data->body;
236 switch (data->count) {
237 case 20:
238 protocol = RC_PROTO_RC6_6A_20;
239 toggle = 0;
240 break;
241 case 24:
242 protocol = RC_PROTO_RC6_6A_24;
243 toggle = 0;
244 break;
245 case 32:
246 switch (scancode & RC6_6A_LCC_MASK) {
247 case RC6_6A_MCE_CC:
248 case RC6_6A_KATHREIN_CC:
249 protocol = RC_PROTO_RC6_MCE;
250 toggle = !!(scancode & RC6_6A_MCE_TOGGLE_MASK);
251 scancode &= ~RC6_6A_MCE_TOGGLE_MASK;
252 break;
253 default:
254 protocol = RC_PROTO_RC6_6A_32;
255 toggle = 0;
256 break;
257 }
258 break;
259 default:
260 dev_dbg(&dev->dev, "RC6(6A) unsupported length\n");
261 goto out;
262 }
263
264 dev_dbg(&dev->dev, "RC6(6A) proto 0x%04x, scancode 0x%08x (toggle: %u)\n",
265 protocol, scancode, toggle);
266 break;
267 default:
268 dev_dbg(&dev->dev, "RC6 unknown mode\n");
269 goto out;
270 }
271
272 rc_keydown(dev, protocol, scancode, toggle);
273 data->state = STATE_INACTIVE;
274 return 0;
275 }
276
277 out:
278 dev_dbg(&dev->dev, "RC6 decode failed at state %i (%uus %s)\n",
279 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
280 data->state = STATE_INACTIVE;
281 return -EINVAL;
282 }
283
284 static const struct ir_raw_timings_manchester ir_rc6_timings[4] = {
285 {
286 .leader_pulse = RC6_PREFIX_PULSE,
287 .leader_space = RC6_PREFIX_SPACE,
288 .clock = RC6_UNIT,
289 .invert = 1,
290 },
291 {
292 .clock = RC6_UNIT * 2,
293 .invert = 1,
294 },
295 {
296 .clock = RC6_UNIT,
297 .invert = 1,
298 .trailer_space = RC6_SUFFIX_SPACE,
299 },
300 };
301
302 /**
303 * ir_rc6_encode() - Encode a scancode as a stream of raw events
304 *
305 * @protocol: protocol to encode
306 * @scancode: scancode to encode
307 * @events: array of raw ir events to write into
308 * @max: maximum size of @events
309 *
310 * Returns: The number of events written.
311 * -ENOBUFS if there isn't enough space in the array to fit the
312 * encoding. In this case all @max events will have been written.
313 * -EINVAL if the scancode is ambiguous or invalid.
314 */
ir_rc6_encode(enum rc_proto protocol,u32 scancode,struct ir_raw_event * events,unsigned int max)315 static int ir_rc6_encode(enum rc_proto protocol, u32 scancode,
316 struct ir_raw_event *events, unsigned int max)
317 {
318 int ret;
319 struct ir_raw_event *e = events;
320
321 if (protocol == RC_PROTO_RC6_0) {
322 /* Modulate the header (Start Bit & Mode-0) */
323 ret = ir_raw_gen_manchester(&e, max - (e - events),
324 &ir_rc6_timings[0],
325 RC6_HEADER_NBITS, (1 << 3));
326 if (ret < 0)
327 return ret;
328
329 /* Modulate Trailer Bit */
330 ret = ir_raw_gen_manchester(&e, max - (e - events),
331 &ir_rc6_timings[1], 1, 0);
332 if (ret < 0)
333 return ret;
334
335 /* Modulate rest of the data */
336 ret = ir_raw_gen_manchester(&e, max - (e - events),
337 &ir_rc6_timings[2], RC6_0_NBITS,
338 scancode);
339 if (ret < 0)
340 return ret;
341
342 } else {
343 int bits;
344
345 switch (protocol) {
346 case RC_PROTO_RC6_MCE:
347 case RC_PROTO_RC6_6A_32:
348 bits = 32;
349 break;
350 case RC_PROTO_RC6_6A_24:
351 bits = 24;
352 break;
353 case RC_PROTO_RC6_6A_20:
354 bits = 20;
355 break;
356 default:
357 return -EINVAL;
358 }
359
360 /* Modulate the header (Start Bit & Header-version 6 */
361 ret = ir_raw_gen_manchester(&e, max - (e - events),
362 &ir_rc6_timings[0],
363 RC6_HEADER_NBITS, (1 << 3 | 6));
364 if (ret < 0)
365 return ret;
366
367 /* Modulate Trailer Bit */
368 ret = ir_raw_gen_manchester(&e, max - (e - events),
369 &ir_rc6_timings[1], 1, 0);
370 if (ret < 0)
371 return ret;
372
373 /* Modulate rest of the data */
374 ret = ir_raw_gen_manchester(&e, max - (e - events),
375 &ir_rc6_timings[2],
376 bits,
377 scancode);
378 if (ret < 0)
379 return ret;
380 }
381
382 return e - events;
383 }
384
385 static struct ir_raw_handler rc6_handler = {
386 .protocols = RC_PROTO_BIT_RC6_0 | RC_PROTO_BIT_RC6_6A_20 |
387 RC_PROTO_BIT_RC6_6A_24 | RC_PROTO_BIT_RC6_6A_32 |
388 RC_PROTO_BIT_RC6_MCE,
389 .decode = ir_rc6_decode,
390 .encode = ir_rc6_encode,
391 .carrier = 36000,
392 .min_timeout = RC6_SUFFIX_SPACE,
393 };
394
ir_rc6_decode_init(void)395 static int __init ir_rc6_decode_init(void)
396 {
397 ir_raw_handler_register(&rc6_handler);
398
399 printk(KERN_INFO "IR RC6 protocol handler initialized\n");
400 return 0;
401 }
402
ir_rc6_decode_exit(void)403 static void __exit ir_rc6_decode_exit(void)
404 {
405 ir_raw_handler_unregister(&rc6_handler);
406 }
407
408 module_init(ir_rc6_decode_init);
409 module_exit(ir_rc6_decode_exit);
410
411 MODULE_LICENSE("GPL");
412 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
413 MODULE_DESCRIPTION("RC6 IR protocol decoder");
414