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_type protocol;
93 if (!(dev->enabled_protocols &
94 (RC_BIT_RC6_0 | RC_BIT_RC6_6A_20 | RC_BIT_RC6_6A_24 |
95 RC_BIT_RC6_6A_32 | RC_BIT_RC6_MCE)))
98 if (!is_timing_event(ev)) {
100 data->state = STATE_INACTIVE;
104 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
108 IR_dprintk(2, "RC6 decode started at state %i (%uus %s)\n",
109 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
111 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
114 switch (data->state) {
120 /* Note: larger margin on first pulse since each RC6_UNIT
121 is quite short and some hardware takes some time to
122 adjust to the signal */
123 if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT))
126 data->state = STATE_PREFIX_SPACE;
130 case STATE_PREFIX_SPACE:
134 if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2))
137 data->state = STATE_HEADER_BIT_START;
141 case STATE_HEADER_BIT_START:
142 if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
149 data->state = STATE_HEADER_BIT_END;
152 case STATE_HEADER_BIT_END:
153 if (!is_transition(&ev, &dev->raw->prev_ev))
156 if (data->count == RC6_HEADER_NBITS)
157 data->state = STATE_TOGGLE_START;
159 data->state = STATE_HEADER_BIT_START;
161 decrease_duration(&ev, RC6_BIT_END);
164 case STATE_TOGGLE_START:
165 if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2))
168 data->toggle = ev.pulse;
169 data->state = STATE_TOGGLE_END;
172 case STATE_TOGGLE_END:
173 if (!is_transition(&ev, &dev->raw->prev_ev) ||
174 !geq_margin(ev.duration, RC6_TOGGLE_END, RC6_UNIT / 2))
177 if (!(data->header & RC6_STARTBIT_MASK)) {
178 IR_dprintk(1, "RC6 invalid start bit\n");
182 data->state = STATE_BODY_BIT_START;
183 decrease_duration(&ev, RC6_TOGGLE_END);
187 switch (rc6_mode(data)) {
189 data->wanted_bits = RC6_0_NBITS;
192 data->wanted_bits = RC6_6A_NBITS;
195 IR_dprintk(1, "RC6 unknown mode\n");
200 case STATE_BODY_BIT_START:
201 if (eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) {
202 /* Discard LSB's that won't fit in data->body */
203 if (data->count++ < CHAR_BIT * sizeof data->body) {
208 data->state = STATE_BODY_BIT_END;
210 } else if (RC6_MODE_6A == rc6_mode(data) && !ev.pulse &&
211 geq_margin(ev.duration, RC6_SUFFIX_SPACE, RC6_UNIT / 2)) {
212 data->state = STATE_FINISHED;
217 case STATE_BODY_BIT_END:
218 if (!is_transition(&ev, &dev->raw->prev_ev))
221 if (data->count == data->wanted_bits)
222 data->state = STATE_FINISHED;
224 data->state = STATE_BODY_BIT_START;
226 decrease_duration(&ev, RC6_BIT_END);
233 switch (rc6_mode(data)) {
235 scancode = data->body;
236 toggle = data->toggle;
237 protocol = RC_TYPE_RC6_0;
238 IR_dprintk(1, "RC6(0) scancode 0x%04x (toggle: %u)\n",
243 if (data->count > CHAR_BIT * sizeof data->body) {
244 IR_dprintk(1, "RC6 too many (%u) data bits\n",
249 scancode = data->body;
250 switch (data->count) {
252 protocol = RC_TYPE_RC6_6A_20;
256 protocol = RC_BIT_RC6_6A_24;
260 if ((scancode & RC6_6A_LCC_MASK) == RC6_6A_MCE_CC) {
261 protocol = RC_TYPE_RC6_MCE;
262 toggle = !!(scancode & RC6_6A_MCE_TOGGLE_MASK);
263 scancode &= ~RC6_6A_MCE_TOGGLE_MASK;
265 protocol = RC_BIT_RC6_6A_32;
270 IR_dprintk(1, "RC6(6A) unsupported length\n");
274 IR_dprintk(1, "RC6(6A) proto 0x%04x, scancode 0x%08x (toggle: %u)\n",
275 protocol, scancode, toggle);
278 IR_dprintk(1, "RC6 unknown mode\n");
282 rc_keydown(dev, protocol, scancode, toggle);
283 data->state = STATE_INACTIVE;
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;
294 static struct ir_raw_handler rc6_handler = {
295 .protocols = RC_BIT_RC6_0 | RC_BIT_RC6_6A_20 |
296 RC_BIT_RC6_6A_24 | RC_BIT_RC6_6A_32 |
298 .decode = ir_rc6_decode,
301 static int __init ir_rc6_decode_init(void)
303 ir_raw_handler_register(&rc6_handler);
305 printk(KERN_INFO "IR RC6 protocol handler initialized\n");
309 static void __exit ir_rc6_decode_exit(void)
311 ir_raw_handler_unregister(&rc6_handler);
314 module_init(ir_rc6_decode_init);
315 module_exit(ir_rc6_decode_exit);
317 MODULE_LICENSE("GPL");
318 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
319 MODULE_DESCRIPTION("RC6 IR protocol decoder");