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;
92 if (!(dev->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)))
97 if (!is_timing_event(ev)) {
99 data->state = STATE_INACTIVE;
103 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
107 IR_dprintk(2, "RC6 decode started at state %i (%uus %s)\n",
108 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
110 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
113 switch (data->state) {
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))
125 data->state = STATE_PREFIX_SPACE;
129 case STATE_PREFIX_SPACE:
133 if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2))
136 data->state = STATE_HEADER_BIT_START;
140 case STATE_HEADER_BIT_START:
141 if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
148 data->state = STATE_HEADER_BIT_END;
151 case STATE_HEADER_BIT_END:
152 if (!is_transition(&ev, &dev->raw->prev_ev))
155 if (data->count == RC6_HEADER_NBITS)
156 data->state = STATE_TOGGLE_START;
158 data->state = STATE_HEADER_BIT_START;
160 decrease_duration(&ev, RC6_BIT_END);
163 case STATE_TOGGLE_START:
164 if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2))
167 data->toggle = ev.pulse;
168 data->state = STATE_TOGGLE_END;
171 case STATE_TOGGLE_END:
172 if (!is_transition(&ev, &dev->raw->prev_ev) ||
173 !geq_margin(ev.duration, RC6_TOGGLE_END, RC6_UNIT / 2))
176 if (!(data->header & RC6_STARTBIT_MASK)) {
177 IR_dprintk(1, "RC6 invalid start bit\n");
181 data->state = STATE_BODY_BIT_START;
182 decrease_duration(&ev, RC6_TOGGLE_END);
186 switch (rc6_mode(data)) {
188 data->wanted_bits = RC6_0_NBITS;
191 data->wanted_bits = RC6_6A_NBITS;
194 IR_dprintk(1, "RC6 unknown mode\n");
199 case STATE_BODY_BIT_START:
200 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) {
207 data->state = STATE_BODY_BIT_END;
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;
216 case STATE_BODY_BIT_END:
217 if (!is_transition(&ev, &dev->raw->prev_ev))
220 if (data->count == data->wanted_bits)
221 data->state = STATE_FINISHED;
223 data->state = STATE_BODY_BIT_START;
225 decrease_duration(&ev, RC6_BIT_END);
232 switch (rc6_mode(data)) {
234 scancode = data->body;
235 toggle = data->toggle;
236 IR_dprintk(1, "RC6(0) scancode 0x%04x (toggle: %u)\n",
240 if (data->count > CHAR_BIT * sizeof data->body) {
241 IR_dprintk(1, "RC6 too many (%u) data bits\n",
246 scancode = data->body;
247 if (data->count == RC6_6A_32_NBITS &&
248 (scancode & RC6_6A_LCC_MASK) == RC6_6A_MCE_CC) {
250 toggle = (scancode & RC6_6A_MCE_TOGGLE_MASK) ? 1 : 0;
251 scancode &= ~RC6_6A_MCE_TOGGLE_MASK;
255 IR_dprintk(1, "RC6(6A) scancode 0x%08x (toggle: %u)\n",
259 IR_dprintk(1, "RC6 unknown mode\n");
263 rc_keydown(dev, scancode, toggle);
264 data->state = STATE_INACTIVE;
269 IR_dprintk(1, "RC6 decode failed at state %i (%uus %s)\n",
270 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
271 data->state = STATE_INACTIVE;
275 static struct ir_raw_handler rc6_handler = {
276 .protocols = RC_BIT_RC6_0 | RC_BIT_RC6_6A_20 |
277 RC_BIT_RC6_6A_24 | RC_BIT_RC6_6A_32 |
279 .decode = ir_rc6_decode,
282 static int __init ir_rc6_decode_init(void)
284 ir_raw_handler_register(&rc6_handler);
286 printk(KERN_INFO "IR RC6 protocol handler initialized\n");
290 static void __exit ir_rc6_decode_exit(void)
292 ir_raw_handler_unregister(&rc6_handler);
295 module_init(ir_rc6_decode_init);
296 module_exit(ir_rc6_decode_exit);
298 MODULE_LICENSE("GPL");
299 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
300 MODULE_DESCRIPTION("RC6 IR protocol decoder");