Gitiles
Code Review Sign In
gerrit-public.fairphone.software / kernel / msm-4.9 / a3572c34da8dacc78a629211a91cf34e9b408701 / . / drivers / media / IR / ir-nec-decoder.c
blob: 16360eb4055b69ec8ea3d46ab37ded3ed2e8d476 [file] [log] [blame]
Mauro Carvalho Chehaba3572c32010-03-20 20:59:44 -0300[diff] [blame^]1/* ir-raw-event.c - handle IR Pulse/Space event
2 *
3 * Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com>
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 <media/ir-core.h>
16
17/* Start time: 4.5 ms */
18#define MIN_START_TIME 3900000
19#define MAX_START_TIME 5100000
20
21/* Pulse time: 560 us */
22#define MIN_PULSE_TIME 460000
23#define MAX_PULSE_TIME 660000
24
25/* Bit 1 space time: 2.25ms-560 us */
26#define MIN_BIT1_TIME 1490000
27#define MAX_BIT1_TIME 1890000
28
29/* Bit 0 space time: 1.12ms-560 us */
30#define MIN_BIT0_TIME 360000
31#define MAX_BIT0_TIME 760000
32
33
34/** Decode NEC pulsecode. This code can take up to 76.5 ms to run.
35 Unfortunately, using IRQ to decode pulse didn't work, since it uses
36 a pulse train of 38KHz. This means one pulse on each 52 us
37*/
38
39int ir_nec_decode(struct input_dev *input_dev,
40 struct ir_raw_event *evs,
41 int len)
42{
43 int i, count = -1;
44 int ircode = 0, not_code = 0;
45#if 0
46 /* Needed only after porting the event code to the decoder */
47 struct ir_input_dev *ir = input_get_drvdata(input_dev);
48#endif
49
50 /* Be sure that the first event is an start one and is a pulse */
51 for (i = 0; i < len; i++) {
52 if (evs[i].type & (IR_START_EVENT | IR_PULSE))
53 break;
54 }
55 i++; /* First event doesn't contain data */
56
57 if (i >= len)
58 return 0;
59
60 /* First space should have 4.5 ms otherwise is not NEC protocol */
61 if ((evs[i].delta.tv_nsec < MIN_START_TIME) |
62 (evs[i].delta.tv_nsec > MAX_START_TIME) |
63 (evs[i].type != IR_SPACE))
64 goto err;
65
66 /*
67 * FIXME: need to implement the repeat sequence
68 */
69
70 count = 0;
71 for (i++; i < len; i++) {
72 int bit;
73
74 if ((evs[i].delta.tv_nsec < MIN_PULSE_TIME) |
75 (evs[i].delta.tv_nsec > MAX_PULSE_TIME) |
76 (evs[i].type != IR_PULSE))
77 goto err;
78
79 if (++i >= len)
80 goto err;
81 if (evs[i].type != IR_SPACE)
82 goto err;
83
84 if ((evs[i].delta.tv_nsec > MIN_BIT1_TIME) &&
85 (evs[i].delta.tv_nsec < MAX_BIT1_TIME))
86 bit = 1;
87 else if ((evs[i].delta.tv_nsec > MIN_BIT0_TIME) &&
88 (evs[i].delta.tv_nsec < MAX_BIT0_TIME))
89 bit = 0;
90 else
91 goto err;
92
93 if (bit) {
94 int shift = count;
95 /* Address first, then command */
96 if (shift < 8) {
97 shift += 8;
98 ircode |= 1 << shift;
99 } else if (shift < 16) {
100 not_code |= 1 << shift;
101 } else if (shift < 24) {
102 shift -= 16;
103 ircode |= 1 << shift;
104 } else {
105 shift -= 24;
106 not_code |= 1 << shift;
107 }
108 }
109 if (++count == 32)
110 break;
111 }
112
113 /*
114 * Fixme: may need to accept Extended NEC protocol?
115 */
116 if ((ircode & ~not_code) != ircode) {
117 IR_dprintk(1, "NEC checksum error: code 0x%04x, not-code 0x%04x\n",
118 ircode, not_code);
119 return -EINVAL;
120 }
121
122 IR_dprintk(1, "NEC scancode 0x%04x\n", ircode);
123
124 return ircode;
125err:
126 IR_dprintk(1, "NEC decoded failed at bit %d while decoding %luus time\n",
127 count, (evs[i].delta.tv_nsec + 500) / 1000);
128
129 return -EINVAL;
130}
131EXPORT_SYMBOL_GPL(ir_nec_decode);