/* ir-nec-decoder.c - handle NEC IR Pulse/Space protocol
*
* Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <media/ir-core.h>
/* Start time: 4.5 ms + 560 us of the next pulse */
#define MIN_START_TIME (3900000 + 560000)
#define MAX_START_TIME (5100000 + 560000)
/* Bit 1 time: 2.25ms us */
#define MIN_BIT1_TIME 2050000
#define MAX_BIT1_TIME 2450000
/* Bit 0 time: 1.12ms us */
#define MIN_BIT0_TIME 920000
#define MAX_BIT0_TIME 1320000
/* Total IR code is 110 ms, including the 9 ms for the start pulse */
#define MAX_NEC_TIME 4000000
/* Total IR code is 110 ms, including the 9 ms for the start pulse */
#define MIN_REPEAT_TIME 99000000
#define MAX_REPEAT_TIME 112000000
/* Repeat time: 2.25ms us */
#define MIN_REPEAT_START_TIME 2050000
#define MAX_REPEAT_START_TIME 3000000
#define REPEAT_TIME 240 /* ms */
/** is_repeat - Check if it is a NEC repeat event
* @input_dev: the struct input_dev descriptor of the device
* @pos: the position of the first event
* @len: the length of the buffer
*/
static int is_repeat(struct ir_raw_event *evs, int len, int pos)
{
if ((evs[pos].delta.tv_nsec < MIN_REPEAT_START_TIME) ||
(evs[pos].delta.tv_nsec > MAX_REPEAT_START_TIME))
return 0;
if (++pos >= len)
return 0;
if ((evs[pos].delta.tv_nsec < MIN_REPEAT_TIME) ||
(evs[pos].delta.tv_nsec > MAX_REPEAT_TIME))
return 0;
return 1;
}
/**
* __ir_nec_decode() - Decode one NEC pulsecode
* @input_dev: the struct input_dev descriptor of the device
* @evs: event array with type/duration of pulse/space
* @len: length of the array
* @pos: position to start seeking for a code
* This function returns -EINVAL if no pulse got decoded,
* 0 if buffer is empty and 1 if one keycode were handled.
*/
static int __ir_nec_decode(struct input_dev *input_dev,
struct ir_raw_event *evs,
int len, int *pos)
{
struct ir_input_dev *ir = input_get_drvdata(input_dev);
int count = -1;
int ircode = 0, not_code = 0;
/* Be sure that the first event is an start one and is a pulse */
for (; *pos < len; (*pos)++) {
/* Very long delays are considered as start events */
if (evs[*pos].delta.tv_nsec > MAX_NEC_TIME)
break;
if (evs[*pos].type & IR_START_EVENT)
break;
IR_dprintk(1, "%luus: Spurious NEC %s\n",
(evs[*pos].delta.tv_nsec + 500) / 1000,
(evs[*pos].type & IR_SPACE) ? "space" : "pulse");
}
if (*pos >= len)
return 0;
(*pos)++; /* First event doesn't contain data */
if (evs[*pos].type != IR_PULSE)
goto err;
/* Check if it is a NEC repeat event */
if (is_repeat(evs, len, *pos)) {
*pos += 2;
if (ir->keypressed) {
mod_timer(&ir->raw->timer_keyup,
jiffies + msecs_to_jiffies(REPEAT_TIME));
IR_dprintk(1, "NEC repeat event\n");
return 1;
} else {
IR_dprintk(1, "missing NEC repeat event\n");
return 0;
}
}
/* First space should have 4.5 ms otherwise is not NEC protocol */
if ((evs[*pos].delta.tv_nsec < MIN_START_TIME) ||
(evs[*pos].delta.tv_nsec > MAX_START_TIME))
goto err;
count = 0;
for ((*pos)++; *pos < len; (*pos)++) {
int bit;
if ((evs[*pos].delta.tv_nsec > MIN_BIT1_TIME) &&
(evs[*pos].delta.tv_nsec < MAX_BIT1_TIME))
bit = 1;
else if ((evs[*pos].delta.tv_nsec > MIN_BIT0_TIME) &&
(evs[*pos].delta.tv_nsec < MAX_BIT0_TIME))
bit = 0;
else
goto err;
if (bit) {
int shift = count;
/* Address first, then command */
if (shift < 8) {
shift += 8;
ircode |= 1 << shift;
} else if (shift < 16) {
not_code |= 1 << shift;
} else if (shift < 24) {
shift -= 16;
ircode |= 1 << shift;
} else {
shift -= 24;
not_code |= 1 << shift;
}
}
if (++count == 32)
break;
}
(*pos)++;
/*
* Fixme: may need to accept Extended NEC protocol?
*/
if ((ircode & ~not_code) != ircode) {
IR_dprintk(1, "NEC checksum error: code 0x%04x, not-code 0x%04x\n",
ircode, not_code);
return -EINVAL;
}
IR_dprintk(1, "NEC scancode 0x%04x\n", ircode);
ir_keydown(input_dev, ircode);
mod_timer(&ir->raw->timer_keyup,
jiffies + msecs_to_jiffies(REPEAT_TIME));
return 1;
err:
IR_dprintk(1, "NEC decoded failed at bit %d (%s) while decoding %luus time\n",
count,
(evs[*pos].type & IR_SPACE) ? "space" : "pulse",
(evs[*pos].delta.tv_nsec + 500) / 1000);
return -EINVAL;
}
/**
* __ir_nec_decode() - Decodes all NEC pulsecodes on a given array
* @input_dev: the struct input_dev descriptor of the device
* @evs: event array with type/duration of pulse/space
* @len: length of the array
* This function returns the number of decoded pulses
*/
static int ir_nec_decode(struct input_dev *input_dev,
struct ir_raw_event *evs,
int len)
{
int pos = 0;
int rc = 0;
while (pos < len) {
if (__ir_nec_decode(input_dev, evs, len, &pos) > 0)
rc++;
}
return rc;
}
static struct ir_raw_handler nec_handler = {
.decode = ir_nec_decode,
};
static int __init ir_nec_decode_init(void)
{
ir_raw_handler_register(&nec_handler);
printk(KERN_INFO "IR NEC protocol handler initialized\n");
return 0;
}
static void __exit ir_nec_decode_exit(void)
{
ir_raw_handler_unregister(&nec_handler);
}
module_init(ir_nec_decode_init);
module_exit(ir_nec_decode_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@redhat.com>");
MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
MODULE_DESCRIPTION("NEC IR protocol decoder");
