Linux Kernel  3.7.1
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
ir-rc6-decoder.c
Go to the documentation of this file.
1 /* ir-rc6-decoder.c - A decoder for the RC6 IR protocol
2  *
3  * Copyright (C) 2010 by David Härdeman <[email protected]>
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 #ifndef CHAR_BIT
44 #define CHAR_BIT 8 /* Normally in <limits.h> */
45 #endif
46 
47 enum rc6_mode {
48  RC6_MODE_0,
49  RC6_MODE_6A,
50  RC6_MODE_UNKNOWN,
51 };
52 
53 enum 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 
65 static enum rc6_mode rc6_mode(struct rc6_dec *data)
66 {
67  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 
86 static int ir_rc6_decode(struct rc_dev *dev, struct ir_raw_event ev)
87 {
88  struct rc6_dec *data = &dev->raw->rc6;
89  u32 scancode;
90  u8 toggle;
91 
92  if (!(dev->raw->enabled_protocols & RC_TYPE_RC6))
93  return 0;
94 
95  if (!is_timing_event(ev)) {
96  if (ev.reset)
97  data->state = STATE_INACTIVE;
98  return 0;
99  }
100 
101  if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
102  goto out;
103 
104 again:
105  IR_dprintk(2, "RC6 decode started at state %i (%uus %s)\n",
106  data->state, TO_US(ev.duration), TO_STR(ev.pulse));
107 
108  if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2))
109  return 0;
110 
111  switch (data->state) {
112 
113  case STATE_INACTIVE:
114  if (!ev.pulse)
115  break;
116 
117  /* Note: larger margin on first pulse since each RC6_UNIT
118  is quite short and some hardware takes some time to
119  adjust to the signal */
120  if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT))
121  break;
122 
123  data->state = STATE_PREFIX_SPACE;
124  data->count = 0;
125  return 0;
126 
127  case STATE_PREFIX_SPACE:
128  if (ev.pulse)
129  break;
130 
131  if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2))
132  break;
133 
134  data->state = STATE_HEADER_BIT_START;
135  data->header = 0;
136  return 0;
137 
138  case STATE_HEADER_BIT_START:
139  if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2))
140  break;
141 
142  data->header <<= 1;
143  if (ev.pulse)
144  data->header |= 1;
145  data->count++;
146  data->state = STATE_HEADER_BIT_END;
147  return 0;
148 
149  case STATE_HEADER_BIT_END:
150  if (!is_transition(&ev, &dev->raw->prev_ev))
151  break;
152 
153  if (data->count == RC6_HEADER_NBITS)
154  data->state = STATE_TOGGLE_START;
155  else
156  data->state = STATE_HEADER_BIT_START;
157 
158  decrease_duration(&ev, RC6_BIT_END);
159  goto again;
160 
161  case STATE_TOGGLE_START:
162  if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2))
163  break;
164 
165  data->toggle = ev.pulse;
166  data->state = STATE_TOGGLE_END;
167  return 0;
168 
169  case STATE_TOGGLE_END:
170  if (!is_transition(&ev, &dev->raw->prev_ev) ||
171  !geq_margin(ev.duration, RC6_TOGGLE_END, RC6_UNIT / 2))
172  break;
173 
174  if (!(data->header & RC6_STARTBIT_MASK)) {
175  IR_dprintk(1, "RC6 invalid start bit\n");
176  break;
177  }
178 
179  data->state = STATE_BODY_BIT_START;
180  decrease_duration(&ev, RC6_TOGGLE_END);
181  data->count = 0;
182  data->body = 0;
183 
184  switch (rc6_mode(data)) {
185  case RC6_MODE_0:
186  data->wanted_bits = RC6_0_NBITS;
187  break;
188  case RC6_MODE_6A:
189  data->wanted_bits = RC6_6A_NBITS;
190  break;
191  default:
192  IR_dprintk(1, "RC6 unknown mode\n");
193  goto out;
194  }
195  goto again;
196 
197  case STATE_BODY_BIT_START:
198  if (eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) {
199  /* Discard LSB's that won't fit in data->body */
200  if (data->count++ < CHAR_BIT * sizeof data->body) {
201  data->body <<= 1;
202  if (ev.pulse)
203  data->body |= 1;
204  }
205  data->state = STATE_BODY_BIT_END;
206  return 0;
207  } else if (RC6_MODE_6A == rc6_mode(data) && !ev.pulse &&
208  geq_margin(ev.duration, RC6_SUFFIX_SPACE, RC6_UNIT / 2)) {
209  data->state = STATE_FINISHED;
210  goto again;
211  }
212  break;
213 
214  case STATE_BODY_BIT_END:
215  if (!is_transition(&ev, &dev->raw->prev_ev))
216  break;
217 
218  if (data->count == data->wanted_bits)
219  data->state = STATE_FINISHED;
220  else
221  data->state = STATE_BODY_BIT_START;
222 
223  decrease_duration(&ev, RC6_BIT_END);
224  goto again;
225 
226  case STATE_FINISHED:
227  if (ev.pulse)
228  break;
229 
230  switch (rc6_mode(data)) {
231  case RC6_MODE_0:
232  scancode = data->body;
233  toggle = data->toggle;
234  IR_dprintk(1, "RC6(0) scancode 0x%04x (toggle: %u)\n",
235  scancode, toggle);
236  break;
237  case RC6_MODE_6A:
238  if (data->count > CHAR_BIT * sizeof data->body) {
239  IR_dprintk(1, "RC6 too many (%u) data bits\n",
240  data->count);
241  goto out;
242  }
243 
244  scancode = data->body;
245  if (data->count == RC6_6A_32_NBITS &&
246  (scancode & RC6_6A_LCC_MASK) == RC6_6A_MCE_CC) {
247  /* MCE RC */
248  toggle = (scancode & RC6_6A_MCE_TOGGLE_MASK) ? 1 : 0;
249  scancode &= ~RC6_6A_MCE_TOGGLE_MASK;
250  } else {
251  toggle = 0;
252  }
253  IR_dprintk(1, "RC6(6A) scancode 0x%08x (toggle: %u)\n",
254  scancode, toggle);
255  break;
256  default:
257  IR_dprintk(1, "RC6 unknown mode\n");
258  goto out;
259  }
260 
261  rc_keydown(dev, scancode, toggle);
262  data->state = STATE_INACTIVE;
263  return 0;
264  }
265 
266 out:
267  IR_dprintk(1, "RC6 decode failed at state %i (%uus %s)\n",
268  data->state, TO_US(ev.duration), TO_STR(ev.pulse));
269  data->state = STATE_INACTIVE;
270  return -EINVAL;
271 }
272 
273 static struct ir_raw_handler rc6_handler = {
274  .protocols = RC_TYPE_RC6,
275  .decode = ir_rc6_decode,
276 };
277 
278 static int __init ir_rc6_decode_init(void)
279 {
280  ir_raw_handler_register(&rc6_handler);
281 
282  printk(KERN_INFO "IR RC6 protocol handler initialized\n");
283  return 0;
284 }
285 
286 static void __exit ir_rc6_decode_exit(void)
287 {
288  ir_raw_handler_unregister(&rc6_handler);
289 }
290 
291 module_init(ir_rc6_decode_init);
292 module_exit(ir_rc6_decode_exit);
293 
294 MODULE_LICENSE("GPL");
295 MODULE_AUTHOR("David Härdeman <[email protected]>");
296 MODULE_DESCRIPTION("RC6 IR protocol decoder");
Generated on Thu Jan 10 2013 13:50:21 for Linux Kernel by   doxygen 1.8.2