408 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/* ir-rc6-decoder.c - A decoder for the RC6 IR protocol3 *4 * Copyright (C) 2010 by David Härdeman <david@hardeman.nu>5 */6 7#include "rc-core-priv.h"8#include <linux/module.h>9 10/*11 * This decoder currently supports:12 * RC6-0-16 (standard toggle bit in header)13 * RC6-6A-20 (no toggle bit)14 * RC6-6A-24 (no toggle bit)15 * RC6-6A-32 (MCE version with toggle bit in body)16 */17 18#define RC6_UNIT 444 /* microseconds */19#define RC6_HEADER_NBITS 4 /* not including toggle bit */20#define RC6_0_NBITS 1621#define RC6_6A_32_NBITS 3222#define RC6_6A_NBITS 128 /* Variable 8..128 */23#define RC6_PREFIX_PULSE (6 * RC6_UNIT)24#define RC6_PREFIX_SPACE (2 * RC6_UNIT)25#define RC6_BIT_START (1 * RC6_UNIT)26#define RC6_BIT_END (1 * RC6_UNIT)27#define RC6_TOGGLE_START (2 * RC6_UNIT)28#define RC6_TOGGLE_END (2 * RC6_UNIT)29#define RC6_SUFFIX_SPACE (6 * RC6_UNIT)30#define RC6_MODE_MASK 0x07 /* for the header bits */31#define RC6_STARTBIT_MASK 0x08 /* for the header bits */32#define RC6_6A_MCE_TOGGLE_MASK 0x8000 /* for the body bits */33#define RC6_6A_LCC_MASK 0xffff0000 /* RC6-6A-32 long customer code mask */34#define RC6_6A_MCE_CC 0x800f0000 /* MCE customer code */35#define RC6_6A_ZOTAC_CC 0x80340000 /* Zotac customer code */36#define RC6_6A_KATHREIN_CC 0x80460000 /* Kathrein RCU-676 customer code */37#ifndef CHAR_BIT38#define CHAR_BIT 8 /* Normally in <limits.h> */39#endif40 41enum rc6_mode {42 RC6_MODE_0,43 RC6_MODE_6A,44 RC6_MODE_UNKNOWN,45};46 47enum rc6_state {48 STATE_INACTIVE,49 STATE_PREFIX_SPACE,50 STATE_HEADER_BIT_START,51 STATE_HEADER_BIT_END,52 STATE_TOGGLE_START,53 STATE_TOGGLE_END,54 STATE_BODY_BIT_START,55 STATE_BODY_BIT_END,56 STATE_FINISHED,57};58 59static enum rc6_mode rc6_mode(struct rc6_dec *data)60{61 switch (data->header & RC6_MODE_MASK) {62 case 0:63 return RC6_MODE_0;64 case 6:65 if (!data->toggle)66 return RC6_MODE_6A;67 fallthrough;68 default:69 return RC6_MODE_UNKNOWN;70 }71}72 73/**74 * ir_rc6_decode() - Decode one RC6 pulse or space75 * @dev: the struct rc_dev descriptor of the device76 * @ev: the struct ir_raw_event descriptor of the pulse/space77 *78 * This function returns -EINVAL if the pulse violates the state machine79 */80static int ir_rc6_decode(struct rc_dev *dev, struct ir_raw_event ev)81{82 struct rc6_dec *data = &dev->raw->rc6;83 u32 scancode;84 u8 toggle;85 enum rc_proto protocol;86 87 if (!is_timing_event(ev)) {88 if (ev.overflow)89 data->state = STATE_INACTIVE;90 return 0;91 }92 93 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))94 goto out;95 96again:97 dev_dbg(&dev->dev, "RC6 decode started at state %i (%uus %s)\n",98 data->state, ev.duration, TO_STR(ev.pulse));99 100 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))101 return 0;102 103 switch (data->state) {104 105 case STATE_INACTIVE:106 if (!ev.pulse)107 break;108 109 /* Note: larger margin on first pulse since each RC6_UNIT110 is quite short and some hardware takes some time to111 adjust to the signal */112 if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT))113 break;114 115 data->state = STATE_PREFIX_SPACE;116 data->count = 0;117 return 0;118 119 case STATE_PREFIX_SPACE:120 if (ev.pulse)121 break;122 123 if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2))124 break;125 126 data->state = STATE_HEADER_BIT_START;127 data->header = 0;128 return 0;129 130 case STATE_HEADER_BIT_START:131 if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))132 break;133 134 data->header <<= 1;135 if (ev.pulse)136 data->header |= 1;137 data->count++;138 data->state = STATE_HEADER_BIT_END;139 return 0;140 141 case STATE_HEADER_BIT_END:142 if (data->count == RC6_HEADER_NBITS)143 data->state = STATE_TOGGLE_START;144 else145 data->state = STATE_HEADER_BIT_START;146 147 decrease_duration(&ev, RC6_BIT_END);148 goto again;149 150 case STATE_TOGGLE_START:151 if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2))152 break;153 154 data->toggle = ev.pulse;155 data->state = STATE_TOGGLE_END;156 return 0;157 158 case STATE_TOGGLE_END:159 if (!(data->header & RC6_STARTBIT_MASK)) {160 dev_dbg(&dev->dev, "RC6 invalid start bit\n");161 break;162 }163 164 data->state = STATE_BODY_BIT_START;165 decrease_duration(&ev, RC6_TOGGLE_END);166 data->count = 0;167 data->body = 0;168 169 switch (rc6_mode(data)) {170 case RC6_MODE_0:171 data->wanted_bits = RC6_0_NBITS;172 break;173 case RC6_MODE_6A:174 data->wanted_bits = RC6_6A_NBITS;175 break;176 default:177 dev_dbg(&dev->dev, "RC6 unknown mode\n");178 goto out;179 }180 goto again;181 182 case STATE_BODY_BIT_START:183 if (eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) {184 /* Discard LSB's that won't fit in data->body */185 if (data->count++ < CHAR_BIT * sizeof data->body) {186 data->body <<= 1;187 if (ev.pulse)188 data->body |= 1;189 }190 data->state = STATE_BODY_BIT_END;191 return 0;192 } else if (RC6_MODE_6A == rc6_mode(data) && !ev.pulse &&193 geq_margin(ev.duration, RC6_SUFFIX_SPACE, RC6_UNIT / 2)) {194 data->state = STATE_FINISHED;195 goto again;196 }197 break;198 199 case STATE_BODY_BIT_END:200 if (data->count == data->wanted_bits)201 data->state = STATE_FINISHED;202 else203 data->state = STATE_BODY_BIT_START;204 205 decrease_duration(&ev, RC6_BIT_END);206 goto again;207 208 case STATE_FINISHED:209 if (ev.pulse)210 break;211 212 switch (rc6_mode(data)) {213 case RC6_MODE_0:214 scancode = data->body;215 toggle = data->toggle;216 protocol = RC_PROTO_RC6_0;217 dev_dbg(&dev->dev, "RC6(0) scancode 0x%04x (toggle: %u)\n",218 scancode, toggle);219 break;220 221 case RC6_MODE_6A:222 if (data->count > CHAR_BIT * sizeof data->body) {223 dev_dbg(&dev->dev, "RC6 too many (%u) data bits\n",224 data->count);225 goto out;226 }227 228 scancode = data->body;229 switch (data->count) {230 case 20:231 protocol = RC_PROTO_RC6_6A_20;232 toggle = 0;233 break;234 case 24:235 protocol = RC_PROTO_RC6_6A_24;236 toggle = 0;237 break;238 case 32:239 switch (scancode & RC6_6A_LCC_MASK) {240 case RC6_6A_MCE_CC:241 case RC6_6A_KATHREIN_CC:242 case RC6_6A_ZOTAC_CC:243 protocol = RC_PROTO_RC6_MCE;244 toggle = !!(scancode & RC6_6A_MCE_TOGGLE_MASK);245 scancode &= ~RC6_6A_MCE_TOGGLE_MASK;246 break;247 default:248 protocol = RC_PROTO_RC6_6A_32;249 toggle = 0;250 break;251 }252 break;253 default:254 dev_dbg(&dev->dev, "RC6(6A) unsupported length\n");255 goto out;256 }257 258 dev_dbg(&dev->dev, "RC6(6A) proto 0x%04x, scancode 0x%08x (toggle: %u)\n",259 protocol, scancode, toggle);260 break;261 default:262 dev_dbg(&dev->dev, "RC6 unknown mode\n");263 goto out;264 }265 266 rc_keydown(dev, protocol, scancode, toggle);267 data->state = STATE_INACTIVE;268 return 0;269 }270 271out:272 dev_dbg(&dev->dev, "RC6 decode failed at state %i (%uus %s)\n",273 data->state, ev.duration, TO_STR(ev.pulse));274 data->state = STATE_INACTIVE;275 return -EINVAL;276}277 278static const struct ir_raw_timings_manchester ir_rc6_timings[4] = {279 {280 .leader_pulse = RC6_PREFIX_PULSE,281 .leader_space = RC6_PREFIX_SPACE,282 .clock = RC6_UNIT,283 .invert = 1,284 },285 {286 .clock = RC6_UNIT * 2,287 .invert = 1,288 },289 {290 .clock = RC6_UNIT,291 .invert = 1,292 .trailer_space = RC6_SUFFIX_SPACE,293 },294};295 296/**297 * ir_rc6_encode() - Encode a scancode as a stream of raw events298 *299 * @protocol: protocol to encode300 * @scancode: scancode to encode301 * @events: array of raw ir events to write into302 * @max: maximum size of @events303 *304 * Returns: The number of events written.305 * -ENOBUFS if there isn't enough space in the array to fit the306 * encoding. In this case all @max events will have been written.307 * -EINVAL if the scancode is ambiguous or invalid.308 */309static int ir_rc6_encode(enum rc_proto protocol, u32 scancode,310 struct ir_raw_event *events, unsigned int max)311{312 int ret;313 struct ir_raw_event *e = events;314 315 if (protocol == RC_PROTO_RC6_0) {316 /* Modulate the header (Start Bit & Mode-0) */317 ret = ir_raw_gen_manchester(&e, max - (e - events),318 &ir_rc6_timings[0],319 RC6_HEADER_NBITS, (1 << 3));320 if (ret < 0)321 return ret;322 323 /* Modulate Trailer Bit */324 ret = ir_raw_gen_manchester(&e, max - (e - events),325 &ir_rc6_timings[1], 1, 0);326 if (ret < 0)327 return ret;328 329 /* Modulate rest of the data */330 ret = ir_raw_gen_manchester(&e, max - (e - events),331 &ir_rc6_timings[2], RC6_0_NBITS,332 scancode);333 if (ret < 0)334 return ret;335 336 } else {337 int bits;338 339 switch (protocol) {340 case RC_PROTO_RC6_MCE:341 case RC_PROTO_RC6_6A_32:342 bits = 32;343 break;344 case RC_PROTO_RC6_6A_24:345 bits = 24;346 break;347 case RC_PROTO_RC6_6A_20:348 bits = 20;349 break;350 default:351 return -EINVAL;352 }353 354 /* Modulate the header (Start Bit & Header-version 6 */355 ret = ir_raw_gen_manchester(&e, max - (e - events),356 &ir_rc6_timings[0],357 RC6_HEADER_NBITS, (1 << 3 | 6));358 if (ret < 0)359 return ret;360 361 /* Modulate Trailer Bit */362 ret = ir_raw_gen_manchester(&e, max - (e - events),363 &ir_rc6_timings[1], 1, 0);364 if (ret < 0)365 return ret;366 367 /* Modulate rest of the data */368 ret = ir_raw_gen_manchester(&e, max - (e - events),369 &ir_rc6_timings[2],370 bits,371 scancode);372 if (ret < 0)373 return ret;374 }375 376 return e - events;377}378 379static struct ir_raw_handler rc6_handler = {380 .protocols = RC_PROTO_BIT_RC6_0 | RC_PROTO_BIT_RC6_6A_20 |381 RC_PROTO_BIT_RC6_6A_24 | RC_PROTO_BIT_RC6_6A_32 |382 RC_PROTO_BIT_RC6_MCE,383 .decode = ir_rc6_decode,384 .encode = ir_rc6_encode,385 .carrier = 36000,386 .min_timeout = RC6_SUFFIX_SPACE,387};388 389static int __init ir_rc6_decode_init(void)390{391 ir_raw_handler_register(&rc6_handler);392 393 printk(KERN_INFO "IR RC6 protocol handler initialized\n");394 return 0;395}396 397static void __exit ir_rc6_decode_exit(void)398{399 ir_raw_handler_unregister(&rc6_handler);400}401 402module_init(ir_rc6_decode_init);403module_exit(ir_rc6_decode_exit);404 405MODULE_LICENSE("GPL");406MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");407MODULE_DESCRIPTION("RC6 IR protocol decoder");408