1 /* ir-nec-decoder.c - handle NEC IR Pulse/Space protocol
3 * Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com>
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 <linux/bitrev.h>
16 #include "ir-core-priv.h"
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
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
45 * This function returns -EINVAL if the pulse violates the state machine
47 static int ir_nec_decode(struct input_dev
*input_dev
, struct ir_raw_event ev
)
49 struct ir_input_dev
*ir_dev
= input_get_drvdata(input_dev
);
50 struct nec_dec
*data
= &ir_dev
->raw
->nec
;
52 u8 address
, not_address
, command
, not_command
;
54 if (!(ir_dev
->raw
->enabled_protocols
& IR_TYPE_NEC
))
57 if (!is_timing_event(ev
)) {
59 data
->state
= STATE_INACTIVE
;
63 IR_dprintk(2, "NEC decode started at state %d (%uus %s)\n",
64 data
->state
, TO_US(ev
.duration
), TO_STR(ev
.pulse
));
66 switch (data
->state
) {
72 if (eq_margin(ev
.duration
, NEC_HEADER_PULSE
, NEC_UNIT
/ 2)) {
73 data
->is_nec_x
= false;
74 data
->necx_repeat
= false;
75 } else if (eq_margin(ev
.duration
, NECX_HEADER_PULSE
, NEC_UNIT
/ 2))
76 data
->is_nec_x
= true;
81 data
->state
= STATE_HEADER_SPACE
;
84 case STATE_HEADER_SPACE
:
88 if (eq_margin(ev
.duration
, NEC_HEADER_SPACE
, NEC_UNIT
/ 2)) {
89 data
->state
= STATE_BIT_PULSE
;
91 } else if (eq_margin(ev
.duration
, NEC_REPEAT_SPACE
, NEC_UNIT
/ 2)) {
93 IR_dprintk(1, "Repeat last key\n");
94 data
->state
= STATE_TRAILER_PULSE
;
100 case STATE_BIT_PULSE
:
104 if (!eq_margin(ev
.duration
, NEC_BIT_PULSE
, NEC_UNIT
/ 2))
107 data
->state
= STATE_BIT_SPACE
;
110 case STATE_BIT_SPACE
:
114 if (data
->necx_repeat
&& data
->count
== NECX_REPEAT_BITS
&&
115 geq_margin(ev
.duration
,
116 NEC_TRAILER_SPACE
, NEC_UNIT
/ 2)) {
117 IR_dprintk(1, "Repeat last key\n");
118 ir_repeat(input_dev
);
119 data
->state
= STATE_INACTIVE
;
122 } else if (data
->count
> NECX_REPEAT_BITS
)
123 data
->necx_repeat
= false;
126 if (eq_margin(ev
.duration
, NEC_BIT_1_SPACE
, NEC_UNIT
/ 2))
128 else if (!eq_margin(ev
.duration
, NEC_BIT_0_SPACE
, NEC_UNIT
/ 2))
132 if (data
->count
== NEC_NBITS
)
133 data
->state
= STATE_TRAILER_PULSE
;
135 data
->state
= STATE_BIT_PULSE
;
139 case STATE_TRAILER_PULSE
:
143 if (!eq_margin(ev
.duration
, NEC_TRAILER_PULSE
, NEC_UNIT
/ 2))
146 data
->state
= STATE_TRAILER_SPACE
;
149 case STATE_TRAILER_SPACE
:
153 if (!geq_margin(ev
.duration
, NEC_TRAILER_SPACE
, NEC_UNIT
/ 2))
156 address
= bitrev8((data
->bits
>> 24) & 0xff);
157 not_address
= bitrev8((data
->bits
>> 16) & 0xff);
158 command
= bitrev8((data
->bits
>> 8) & 0xff);
159 not_command
= bitrev8((data
->bits
>> 0) & 0xff);
161 if ((command
^ not_command
) != 0xff) {
162 IR_dprintk(1, "NEC checksum error: received 0x%08x\n",
167 if ((address
^ not_address
) != 0xff) {
169 scancode
= address
<< 16 |
172 IR_dprintk(1, "NEC (Ext) scancode 0x%06x\n", scancode
);
175 scancode
= address
<< 8 | command
;
176 IR_dprintk(1, "NEC scancode 0x%04x\n", scancode
);
180 data
->necx_repeat
= true;
182 ir_keydown(input_dev
, scancode
, 0);
183 data
->state
= STATE_INACTIVE
;
187 IR_dprintk(1, "NEC decode failed at state %d (%uus %s)\n",
188 data
->state
, TO_US(ev
.duration
), TO_STR(ev
.pulse
));
189 data
->state
= STATE_INACTIVE
;
193 static struct ir_raw_handler nec_handler
= {
194 .protocols
= IR_TYPE_NEC
,
195 .decode
= ir_nec_decode
,
198 static int __init
ir_nec_decode_init(void)
200 ir_raw_handler_register(&nec_handler
);
202 printk(KERN_INFO
"IR NEC protocol handler initialized\n");
206 static void __exit
ir_nec_decode_exit(void)
208 ir_raw_handler_unregister(&nec_handler
);
211 module_init(ir_nec_decode_init
);
212 module_exit(ir_nec_decode_exit
);
214 MODULE_LICENSE("GPL");
215 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@redhat.com>");
216 MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
217 MODULE_DESCRIPTION("NEC IR protocol decoder");