]> git.karo-electronics.de Git - mv-sheeva.git/blob - drivers/media/IR/ir-nec-decoder.c
Merge branch 'for-linus' of git://neil.brown.name/md
[mv-sheeva.git] / drivers / media / IR / ir-nec-decoder.c
1 /* ir-nec-decoder.c - handle NEC IR Pulse/Space protocol
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 <linux/bitrev.h>
16 #include "ir-core-priv.h"
17
18 #define NEC_NBITS               32
19 #define NEC_UNIT                562500  /* ns */
20 #define NEC_HEADER_PULSE        (16 * NEC_UNIT)
21 #define NECX_HEADER_PULSE       (8  * NEC_UNIT) /* Less common NEC variant */
22 #define NEC_HEADER_SPACE        (8  * NEC_UNIT)
23 #define NEC_REPEAT_SPACE        (4  * NEC_UNIT)
24 #define NEC_BIT_PULSE           (1  * NEC_UNIT)
25 #define NEC_BIT_0_SPACE         (1  * NEC_UNIT)
26 #define NEC_BIT_1_SPACE         (3  * NEC_UNIT)
27 #define NEC_TRAILER_PULSE       (1  * NEC_UNIT)
28 #define NEC_TRAILER_SPACE       (10 * NEC_UNIT) /* even longer in reality */
29 #define NECX_REPEAT_BITS        1
30
31 enum nec_state {
32         STATE_INACTIVE,
33         STATE_HEADER_SPACE,
34         STATE_BIT_PULSE,
35         STATE_BIT_SPACE,
36         STATE_TRAILER_PULSE,
37         STATE_TRAILER_SPACE,
38 };
39
40 /**
41  * ir_nec_decode() - Decode one NEC pulse or space
42  * @input_dev:  the struct input_dev descriptor of the device
43  * @duration:   the struct ir_raw_event descriptor of the pulse/space
44  *
45  * This function returns -EINVAL if the pulse violates the state machine
46  */
47 static int ir_nec_decode(struct input_dev *input_dev, struct ir_raw_event ev)
48 {
49         struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
50         struct nec_dec *data = &ir_dev->raw->nec;
51         u32 scancode;
52         u8 address, not_address, command, not_command;
53
54         if (!(ir_dev->raw->enabled_protocols & IR_TYPE_NEC))
55                 return 0;
56
57         if (IS_RESET(ev)) {
58                 data->state = STATE_INACTIVE;
59                 return 0;
60         }
61
62         IR_dprintk(2, "NEC decode started at state %d (%uus %s)\n",
63                    data->state, TO_US(ev.duration), TO_STR(ev.pulse));
64
65         switch (data->state) {
66
67         case STATE_INACTIVE:
68                 if (!ev.pulse)
69                         break;
70
71                 if (eq_margin(ev.duration, NEC_HEADER_PULSE, NEC_UNIT / 2)) {
72                         data->is_nec_x = false;
73                         data->necx_repeat = false;
74                 } else if (eq_margin(ev.duration, NECX_HEADER_PULSE, NEC_UNIT / 2))
75                         data->is_nec_x = true;
76                 else
77                         break;
78
79                 data->count = 0;
80                 data->state = STATE_HEADER_SPACE;
81                 return 0;
82
83         case STATE_HEADER_SPACE:
84                 if (ev.pulse)
85                         break;
86
87                 if (eq_margin(ev.duration, NEC_HEADER_SPACE, NEC_UNIT / 2)) {
88                         data->state = STATE_BIT_PULSE;
89                         return 0;
90                 } else if (eq_margin(ev.duration, NEC_REPEAT_SPACE, NEC_UNIT / 2)) {
91                         ir_repeat(input_dev);
92                         IR_dprintk(1, "Repeat last key\n");
93                         data->state = STATE_TRAILER_PULSE;
94                         return 0;
95                 }
96
97                 break;
98
99         case STATE_BIT_PULSE:
100                 if (!ev.pulse)
101                         break;
102
103                 if (!eq_margin(ev.duration, NEC_BIT_PULSE, NEC_UNIT / 2))
104                         break;
105
106                 data->state = STATE_BIT_SPACE;
107                 return 0;
108
109         case STATE_BIT_SPACE:
110                 if (ev.pulse)
111                         break;
112
113                 if (data->necx_repeat && data->count == NECX_REPEAT_BITS &&
114                         geq_margin(ev.duration,
115                         NEC_TRAILER_SPACE, NEC_UNIT / 2)) {
116                                 IR_dprintk(1, "Repeat last key\n");
117                                 ir_repeat(input_dev);
118                                 data->state = STATE_INACTIVE;
119                                 return 0;
120
121                 } else if (data->count > NECX_REPEAT_BITS)
122                         data->necx_repeat = false;
123
124                 data->bits <<= 1;
125                 if (eq_margin(ev.duration, NEC_BIT_1_SPACE, NEC_UNIT / 2))
126                         data->bits |= 1;
127                 else if (!eq_margin(ev.duration, NEC_BIT_0_SPACE, NEC_UNIT / 2))
128                         break;
129                 data->count++;
130
131                 if (data->count == NEC_NBITS)
132                         data->state = STATE_TRAILER_PULSE;
133                 else
134                         data->state = STATE_BIT_PULSE;
135
136                 return 0;
137
138         case STATE_TRAILER_PULSE:
139                 if (!ev.pulse)
140                         break;
141
142                 if (!eq_margin(ev.duration, NEC_TRAILER_PULSE, NEC_UNIT / 2))
143                         break;
144
145                 data->state = STATE_TRAILER_SPACE;
146                 return 0;
147
148         case STATE_TRAILER_SPACE:
149                 if (ev.pulse)
150                         break;
151
152                 if (!geq_margin(ev.duration, NEC_TRAILER_SPACE, NEC_UNIT / 2))
153                         break;
154
155                 address     = bitrev8((data->bits >> 24) & 0xff);
156                 not_address = bitrev8((data->bits >> 16) & 0xff);
157                 command     = bitrev8((data->bits >>  8) & 0xff);
158                 not_command = bitrev8((data->bits >>  0) & 0xff);
159
160                 if ((command ^ not_command) != 0xff) {
161                         IR_dprintk(1, "NEC checksum error: received 0x%08x\n",
162                                    data->bits);
163                         break;
164                 }
165
166                 if ((address ^ not_address) != 0xff) {
167                         /* Extended NEC */
168                         scancode = address     << 16 |
169                                    not_address <<  8 |
170                                    command;
171                         IR_dprintk(1, "NEC (Ext) scancode 0x%06x\n", scancode);
172                 } else {
173                         /* Normal NEC */
174                         scancode = address << 8 | command;
175                         IR_dprintk(1, "NEC scancode 0x%04x\n", scancode);
176                 }
177
178                 if (data->is_nec_x)
179                         data->necx_repeat = true;
180
181                 ir_keydown(input_dev, scancode, 0);
182                 data->state = STATE_INACTIVE;
183                 return 0;
184         }
185
186         IR_dprintk(1, "NEC decode failed at state %d (%uus %s)\n",
187                    data->state, TO_US(ev.duration), TO_STR(ev.pulse));
188         data->state = STATE_INACTIVE;
189         return -EINVAL;
190 }
191
192 static struct ir_raw_handler nec_handler = {
193         .protocols      = IR_TYPE_NEC,
194         .decode         = ir_nec_decode,
195 };
196
197 static int __init ir_nec_decode_init(void)
198 {
199         ir_raw_handler_register(&nec_handler);
200
201         printk(KERN_INFO "IR NEC protocol handler initialized\n");
202         return 0;
203 }
204
205 static void __exit ir_nec_decode_exit(void)
206 {
207         ir_raw_handler_unregister(&nec_handler);
208 }
209
210 module_init(ir_nec_decode_init);
211 module_exit(ir_nec_decode_exit);
212
213 MODULE_LICENSE("GPL");
214 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@redhat.com>");
215 MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
216 MODULE_DESCRIPTION("NEC IR protocol decoder");