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David Härdeman784a4932010-04-08 20:04:40 -03001/* 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
Mauro Carvalho Chehabf62de672010-11-09 23:09:57 -030015#include "rc-core-priv.h"
Paul Gortmaker7a707b82011-07-03 14:03:12 -040016#include <linux/module.h>
David Härdeman784a4932010-04-08 20:04:40 -030017
18/*
19 * This decoder currently supports:
20 * RC6-0-16 (standard toggle bit in header)
lawrence rustdb9bc662011-10-31 08:39:32 -030021 * RC6-6A-20 (no toggle bit)
David Härdeman784a4932010-04-08 20:04:40 -030022 * RC6-6A-24 (no toggle bit)
23 * RC6-6A-32 (MCE version with toggle bit in body)
24 */
25
lawrence rustdb9bc662011-10-31 08:39:32 -030026#define RC6_UNIT 444444 /* nanosecs */
David Härdeman784a4932010-04-08 20:04:40 -030027#define RC6_HEADER_NBITS 4 /* not including toggle bit */
28#define RC6_0_NBITS 16
lawrence rustdb9bc662011-10-31 08:39:32 -030029#define RC6_6A_32_NBITS 32
30#define RC6_6A_NBITS 128 /* Variable 8..128 */
David Härdemane40b1122010-04-15 18:46:00 -030031#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)
lawrence rustdb9bc662011-10-31 08:39:32 -030037#define RC6_SUFFIX_SPACE (6 * RC6_UNIT)
David Härdeman784a4932010-04-08 20:04:40 -030038#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 */
lawrence rustdb9bc662011-10-31 08:39:32 -030041#define RC6_6A_LCC_MASK 0xffff0000 /* RC6-6A-32 long customer code mask */
42#define RC6_6A_MCE_CC 0x800f0000 /* MCE customer code */
43#ifndef CHAR_BIT
44#define CHAR_BIT 8 /* Normally in <limits.h> */
45#endif
David Härdeman784a4932010-04-08 20:04:40 -030046
David Härdeman784a4932010-04-08 20:04:40 -030047enum rc6_mode {
48 RC6_MODE_0,
49 RC6_MODE_6A,
50 RC6_MODE_UNKNOWN,
51};
52
53enum rc6_state {
54 STATE_INACTIVE,
55 STATE_PREFIX_SPACE,
56 STATE_HEADER_BIT_START,
57 STATE_HEADER_BIT_END,
58 STATE_TOGGLE_START,
59 STATE_TOGGLE_END,
60 STATE_BODY_BIT_START,
61 STATE_BODY_BIT_END,
62 STATE_FINISHED,
63};
64
David Härdemanc2163692010-06-13 17:29:36 -030065static enum rc6_mode rc6_mode(struct rc6_dec *data)
David Härdeman784a4932010-04-08 20:04:40 -030066{
David Härdeman784a4932010-04-08 20:04:40 -030067 switch (data->header & RC6_MODE_MASK) {
68 case 0:
69 return RC6_MODE_0;
70 case 6:
71 if (!data->toggle)
72 return RC6_MODE_6A;
73 /* fall through */
74 default:
75 return RC6_MODE_UNKNOWN;
76 }
77}
78
79/**
80 * ir_rc6_decode() - Decode one RC6 pulse or space
David Härdemand8b4b582010-10-29 16:08:23 -030081 * @dev: the struct rc_dev descriptor of the device
David Härdemane40b1122010-04-15 18:46:00 -030082 * @ev: the struct ir_raw_event descriptor of the pulse/space
David Härdeman784a4932010-04-08 20:04:40 -030083 *
84 * This function returns -EINVAL if the pulse violates the state machine
85 */
David Härdemand8b4b582010-10-29 16:08:23 -030086static int ir_rc6_decode(struct rc_dev *dev, struct ir_raw_event ev)
David Härdeman784a4932010-04-08 20:04:40 -030087{
David Härdemand8b4b582010-10-29 16:08:23 -030088 struct rc6_dec *data = &dev->raw->rc6;
David Härdeman784a4932010-04-08 20:04:40 -030089 u32 scancode;
90 u8 toggle;
David Härdeman784a4932010-04-08 20:04:40 -030091
David Härdemanc003ab12012-10-11 19:11:54 -030092 if (!(dev->raw->enabled_protocols &
93 (RC_BIT_RC6_0 | RC_BIT_RC6_6A_20 | RC_BIT_RC6_6A_24 |
94 RC_BIT_RC6_6A_32 | RC_BIT_RC6_MCE)))
David Härdeman784a4932010-04-08 20:04:40 -030095 return 0;
96
Maxim Levitsky46519182010-10-16 19:56:28 -030097 if (!is_timing_event(ev)) {
98 if (ev.reset)
99 data->state = STATE_INACTIVE;
David Härdeman784a4932010-04-08 20:04:40 -0300100 return 0;
101 }
102
David Härdemane40b1122010-04-15 18:46:00 -0300103 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
David Härdeman784a4932010-04-08 20:04:40 -0300104 goto out;
105
106again:
David Härdemane40b1122010-04-15 18:46:00 -0300107 IR_dprintk(2, "RC6 decode started at state %i (%uus %s)\n",
108 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
David Härdeman784a4932010-04-08 20:04:40 -0300109
David Härdemane40b1122010-04-15 18:46:00 -0300110 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
David Härdeman784a4932010-04-08 20:04:40 -0300111 return 0;
112
113 switch (data->state) {
114
115 case STATE_INACTIVE:
David Härdemane40b1122010-04-15 18:46:00 -0300116 if (!ev.pulse)
117 break;
118
119 /* Note: larger margin on first pulse since each RC6_UNIT
120 is quite short and some hardware takes some time to
121 adjust to the signal */
122 if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT))
123 break;
124
125 data->state = STATE_PREFIX_SPACE;
126 data->count = 0;
127 return 0;
David Härdeman784a4932010-04-08 20:04:40 -0300128
129 case STATE_PREFIX_SPACE:
David Härdemane40b1122010-04-15 18:46:00 -0300130 if (ev.pulse)
131 break;
132
133 if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2))
134 break;
135
136 data->state = STATE_HEADER_BIT_START;
lawrence rustdb9bc662011-10-31 08:39:32 -0300137 data->header = 0;
David Härdemane40b1122010-04-15 18:46:00 -0300138 return 0;
David Härdeman784a4932010-04-08 20:04:40 -0300139
140 case STATE_HEADER_BIT_START:
David Härdemane40b1122010-04-15 18:46:00 -0300141 if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
142 break;
143
144 data->header <<= 1;
145 if (ev.pulse)
146 data->header |= 1;
147 data->count++;
David Härdemane40b1122010-04-15 18:46:00 -0300148 data->state = STATE_HEADER_BIT_END;
149 return 0;
David Härdeman784a4932010-04-08 20:04:40 -0300150
151 case STATE_HEADER_BIT_END:
David Härdemand8b4b582010-10-29 16:08:23 -0300152 if (!is_transition(&ev, &dev->raw->prev_ev))
David Härdemane40b1122010-04-15 18:46:00 -0300153 break;
David Härdeman784a4932010-04-08 20:04:40 -0300154
David Härdemane40b1122010-04-15 18:46:00 -0300155 if (data->count == RC6_HEADER_NBITS)
156 data->state = STATE_TOGGLE_START;
157 else
158 data->state = STATE_HEADER_BIT_START;
159
160 decrease_duration(&ev, RC6_BIT_END);
161 goto again;
David Härdeman784a4932010-04-08 20:04:40 -0300162
163 case STATE_TOGGLE_START:
David Härdemane40b1122010-04-15 18:46:00 -0300164 if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2))
165 break;
166
167 data->toggle = ev.pulse;
David Härdemane40b1122010-04-15 18:46:00 -0300168 data->state = STATE_TOGGLE_END;
169 return 0;
David Härdeman784a4932010-04-08 20:04:40 -0300170
171 case STATE_TOGGLE_END:
David Härdemand8b4b582010-10-29 16:08:23 -0300172 if (!is_transition(&ev, &dev->raw->prev_ev) ||
David Härdemane40b1122010-04-15 18:46:00 -0300173 !geq_margin(ev.duration, RC6_TOGGLE_END, RC6_UNIT / 2))
174 break;
David Härdeman784a4932010-04-08 20:04:40 -0300175
David Härdemane40b1122010-04-15 18:46:00 -0300176 if (!(data->header & RC6_STARTBIT_MASK)) {
177 IR_dprintk(1, "RC6 invalid start bit\n");
178 break;
David Härdeman784a4932010-04-08 20:04:40 -0300179 }
David Härdemane40b1122010-04-15 18:46:00 -0300180
181 data->state = STATE_BODY_BIT_START;
David Härdemane40b1122010-04-15 18:46:00 -0300182 decrease_duration(&ev, RC6_TOGGLE_END);
183 data->count = 0;
lawrence rustdb9bc662011-10-31 08:39:32 -0300184 data->body = 0;
David Härdemane40b1122010-04-15 18:46:00 -0300185
186 switch (rc6_mode(data)) {
187 case RC6_MODE_0:
188 data->wanted_bits = RC6_0_NBITS;
189 break;
190 case RC6_MODE_6A:
lawrence rustdb9bc662011-10-31 08:39:32 -0300191 data->wanted_bits = RC6_6A_NBITS;
David Härdemane40b1122010-04-15 18:46:00 -0300192 break;
193 default:
194 IR_dprintk(1, "RC6 unknown mode\n");
195 goto out;
196 }
197 goto again;
David Härdeman784a4932010-04-08 20:04:40 -0300198
199 case STATE_BODY_BIT_START:
lawrence rustdb9bc662011-10-31 08:39:32 -0300200 if (eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) {
201 /* Discard LSB's that won't fit in data->body */
202 if (data->count++ < CHAR_BIT * sizeof data->body) {
203 data->body <<= 1;
204 if (ev.pulse)
205 data->body |= 1;
206 }
207 data->state = STATE_BODY_BIT_END;
208 return 0;
209 } else if (RC6_MODE_6A == rc6_mode(data) && !ev.pulse &&
210 geq_margin(ev.duration, RC6_SUFFIX_SPACE, RC6_UNIT / 2)) {
211 data->state = STATE_FINISHED;
212 goto again;
213 }
214 break;
David Härdeman784a4932010-04-08 20:04:40 -0300215
216 case STATE_BODY_BIT_END:
David Härdemand8b4b582010-10-29 16:08:23 -0300217 if (!is_transition(&ev, &dev->raw->prev_ev))
David Härdemane40b1122010-04-15 18:46:00 -0300218 break;
David Härdeman784a4932010-04-08 20:04:40 -0300219
David Härdemane40b1122010-04-15 18:46:00 -0300220 if (data->count == data->wanted_bits)
221 data->state = STATE_FINISHED;
222 else
223 data->state = STATE_BODY_BIT_START;
224
225 decrease_duration(&ev, RC6_BIT_END);
226 goto again;
David Härdeman784a4932010-04-08 20:04:40 -0300227
228 case STATE_FINISHED:
David Härdemane40b1122010-04-15 18:46:00 -0300229 if (ev.pulse)
230 break;
231
David Härdeman784a4932010-04-08 20:04:40 -0300232 switch (rc6_mode(data)) {
233 case RC6_MODE_0:
lawrence rustdb9bc662011-10-31 08:39:32 -0300234 scancode = data->body;
David Härdeman784a4932010-04-08 20:04:40 -0300235 toggle = data->toggle;
236 IR_dprintk(1, "RC6(0) scancode 0x%04x (toggle: %u)\n",
237 scancode, toggle);
238 break;
239 case RC6_MODE_6A:
lawrence rustdb9bc662011-10-31 08:39:32 -0300240 if (data->count > CHAR_BIT * sizeof data->body) {
241 IR_dprintk(1, "RC6 too many (%u) data bits\n",
242 data->count);
243 goto out;
David Härdeman784a4932010-04-08 20:04:40 -0300244 }
245
lawrence rustdb9bc662011-10-31 08:39:32 -0300246 scancode = data->body;
247 if (data->count == RC6_6A_32_NBITS &&
248 (scancode & RC6_6A_LCC_MASK) == RC6_6A_MCE_CC) {
249 /* MCE RC */
250 toggle = (scancode & RC6_6A_MCE_TOGGLE_MASK) ? 1 : 0;
251 scancode &= ~RC6_6A_MCE_TOGGLE_MASK;
252 } else {
253 toggle = 0;
254 }
David Härdeman784a4932010-04-08 20:04:40 -0300255 IR_dprintk(1, "RC6(6A) scancode 0x%08x (toggle: %u)\n",
256 scancode, toggle);
257 break;
258 default:
259 IR_dprintk(1, "RC6 unknown mode\n");
260 goto out;
261 }
262
Mauro Carvalho Chehabca866742010-11-17 13:53:11 -0300263 rc_keydown(dev, scancode, toggle);
David Härdeman784a4932010-04-08 20:04:40 -0300264 data->state = STATE_INACTIVE;
265 return 0;
266 }
267
268out:
David Härdemane40b1122010-04-15 18:46:00 -0300269 IR_dprintk(1, "RC6 decode failed at state %i (%uus %s)\n",
270 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
David Härdeman784a4932010-04-08 20:04:40 -0300271 data->state = STATE_INACTIVE;
272 return -EINVAL;
273}
274
David Härdeman784a4932010-04-08 20:04:40 -0300275static struct ir_raw_handler rc6_handler = {
David Härdemanc003ab12012-10-11 19:11:54 -0300276 .protocols = RC_BIT_RC6_0 | RC_BIT_RC6_6A_20 |
277 RC_BIT_RC6_6A_24 | RC_BIT_RC6_6A_32 |
278 RC_BIT_RC6_MCE,
David Härdeman784a4932010-04-08 20:04:40 -0300279 .decode = ir_rc6_decode,
David Härdeman784a4932010-04-08 20:04:40 -0300280};
281
282static int __init ir_rc6_decode_init(void)
283{
284 ir_raw_handler_register(&rc6_handler);
285
286 printk(KERN_INFO "IR RC6 protocol handler initialized\n");
287 return 0;
288}
289
290static void __exit ir_rc6_decode_exit(void)
291{
292 ir_raw_handler_unregister(&rc6_handler);
293}
294
295module_init(ir_rc6_decode_init);
296module_exit(ir_rc6_decode_exit);
297
298MODULE_LICENSE("GPL");
299MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
300MODULE_DESCRIPTION("RC6 IR protocol decoder");