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// SPDX-License-Identifier: GPL-2.0-only
/* ir-xmp-decoder.c - handle XMP IR Pulse/Space protocol
*
* Copyright (C) 2014 by Marcel Mol
*
* - Based on info from http://www.hifi-remote.com
* - Ignore Toggle=9 frames
* - Ignore XMP-1 XMP-2 difference, always store 16 bit OBC
*/
#include <linux/bitrev.h>
#include <linux/module.h>
#include "rc-core-priv.h"
#define XMP_UNIT 136 /* us */
#define XMP_LEADER 210 /* us */
#define XMP_NIBBLE_PREFIX 760 /* us */
#define XMP_HALFFRAME_SPACE 13800 /* us */
/* should be 80ms but not all duration supliers can go that high */
#define XMP_TRAILER_SPACE 20000
enum xmp_state {
STATE_INACTIVE,
STATE_LEADER_PULSE,
STATE_NIBBLE_SPACE,
};
/**
* ir_xmp_decode() - Decode one XMP pulse or space
* @dev: the struct rc_dev descriptor of the device
* @ev: the struct ir_raw_event descriptor of the pulse/space
*
* This function returns -EINVAL if the pulse violates the state machine
*/
static int ir_xmp_decode(struct rc_dev *dev, struct ir_raw_event ev)
{
struct xmp_dec *data = &dev->raw->xmp;
if (!is_timing_event(ev)) {
if (ev.overflow)
data->state = STATE_INACTIVE;
return 0;
}
dev_dbg(&dev->dev, "XMP decode started at state %d %d (%uus %s)\n",
data->state, data->count, ev.duration, TO_STR(ev.pulse));
switch (data->state) {
case STATE_INACTIVE:
if (!ev.pulse)
break;
if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2)) {
data->count = 0;
data->state = STATE_NIBBLE_SPACE;
}
return 0;
case STATE_LEADER_PULSE:
if (!ev.pulse)
break;
if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2))
data->state = STATE_NIBBLE_SPACE;
return 0;
case STATE_NIBBLE_SPACE:
if (ev.pulse)
break;
if (geq_margin(ev.duration, XMP_TRAILER_SPACE, XMP_NIBBLE_PREFIX)) {
int divider, i;
u8 addr, subaddr, subaddr2, toggle, oem, obc1, obc2, sum1, sum2;
u32 *n;
u32 scancode;
if (data->count != 16) {
dev_dbg(&dev->dev, "received TRAILER period at index %d: %u\n",
data->count, ev.duration);
data->state = STATE_INACTIVE;
return -EINVAL;
}
n = data->durations;
/*
* the 4th nibble should be 15 so base the divider on this
* to transform durations into nibbles. Subtract 2000 from
* the divider to compensate for fluctuations in the signal
*/
divider = (n[3] - XMP_NIBBLE_PREFIX) / 15 - 2000;
if (divider < 50) {
dev_dbg(&dev->dev, "divider to small %d.\n",
divider);
data->state = STATE_INACTIVE;
return -EINVAL;
}
/* convert to nibbles and do some sanity checks */
for (i = 0; i < 16; i++)
n[i] = (n[i] - XMP_NIBBLE_PREFIX) / divider;
sum1 = (15 + n[0] + n[1] + n[2] + n[3] +
n[4] + n[5] + n[6] + n[7]) % 16;
sum2 = (15 + n[8] + n[9] + n[10] + n[11] +
n[12] + n[13] + n[14] + n[15]) % 16;
if (sum1 != 15 || sum2 != 15) {
dev_dbg(&dev->dev, "checksum errors sum1=0x%X sum2=0x%X\n",
sum1, sum2);
data->state = STATE_INACTIVE;
return -EINVAL;
}
subaddr = n[0] << 4 | n[2];
subaddr2 = n[8] << 4 | n[11];
oem = n[4] << 4 | n[5];
addr = n[6] << 4 | n[7];
toggle = n[10];
obc1 = n[12] << 4 | n[13];
obc2 = n[14] << 4 | n[15];
if (subaddr != subaddr2) {
dev_dbg(&dev->dev, "subaddress nibbles mismatch 0x%02X != 0x%02X\n",
subaddr, subaddr2);
data->state = STATE_INACTIVE;
return -EINVAL;
}
if (oem != 0x44)
dev_dbg(&dev->dev, "Warning: OEM nibbles 0x%02X. Expected 0x44\n",
oem);
scancode = addr << 24 | subaddr << 16 |
obc1 << 8 | obc2;
dev_dbg(&dev->dev, "XMP scancode 0x%06x\n", scancode);
if (toggle == 0) {
rc_keydown(dev, RC_PROTO_XMP, scancode, 0);
} else {
rc_repeat(dev);
dev_dbg(&dev->dev, "Repeat last key\n");
}
data->state = STATE_INACTIVE;
return 0;
} else if (geq_margin(ev.duration, XMP_HALFFRAME_SPACE, XMP_NIBBLE_PREFIX)) {
/* Expect 8 or 16 nibble pulses. 16 in case of 'final' frame */
if (data->count == 16) {
dev_dbg(&dev->dev, "received half frame pulse at index %d. Probably a final frame key-up event: %u\n",
data->count, ev.duration);
/*
* TODO: for now go back to half frame position
* so trailer can be found and key press
* can be handled.
*/
data->count = 8;
}
else if (data->count != 8)
dev_dbg(&dev->dev, "received half frame pulse at index %d: %u\n",
data->count, ev.duration);
data->state = STATE_LEADER_PULSE;
return 0;
} else if (geq_margin(ev.duration, XMP_NIBBLE_PREFIX, XMP_UNIT)) {
/* store nibble raw data, decode after trailer */
if (data->count == 16) {
dev_dbg(&dev->dev, "too many pulses (%d) ignoring: %u\n",
data->count, ev.duration);
data->state = STATE_INACTIVE;
return -EINVAL;
}
data->durations[data->count] = ev.duration;
data->count++;
data->state = STATE_LEADER_PULSE;
return 0;
}
break;
}
dev_dbg(&dev->dev, "XMP decode failed at count %d state %d (%uus %s)\n",
data->count, data->state, ev.duration, TO_STR(ev.pulse));
data->state = STATE_INACTIVE;
return -EINVAL;
}
static struct ir_raw_handler xmp_handler = {
.protocols = RC_PROTO_BIT_XMP,
.decode = ir_xmp_decode,
.min_timeout = XMP_TRAILER_SPACE,
};
static int __init ir_xmp_decode_init(void)
{
ir_raw_handler_register(&xmp_handler);
printk(KERN_INFO "IR XMP protocol handler initialized\n");
return 0;
}
static void __exit ir_xmp_decode_exit(void)
{
ir_raw_handler_unregister(&xmp_handler);
}
module_init(ir_xmp_decode_init);
module_exit(ir_xmp_decode_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marcel Mol <marcel@mesa.nl>");
MODULE_AUTHOR("MESA Consulting (http://www.mesa.nl)");
MODULE_DESCRIPTION("XMP IR protocol decoder");
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