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// SPDX-License-Identifier: GPL-2.0-only
/* ir-sharp-decoder.c - handle Sharp IR Pulse/Space protocol
*
* Copyright (C) 2013-2014 Imagination Technologies Ltd.
*
* Based on NEC decoder:
* Copyright (C) 2010 by Mauro Carvalho Chehab
*/
#include <linux/bitrev.h>
#include <linux/module.h>
#include "rc-core-priv.h"
#define SHARP_NBITS 15
#define SHARP_UNIT 40 /* us */
#define SHARP_BIT_PULSE (8 * SHARP_UNIT) /* 320us */
#define SHARP_BIT_0_PERIOD (25 * SHARP_UNIT) /* 1ms (680us space) */
#define SHARP_BIT_1_PERIOD (50 * SHARP_UNIT) /* 2ms (1680ms space) */
#define SHARP_ECHO_SPACE (1000 * SHARP_UNIT) /* 40 ms */
#define SHARP_TRAILER_SPACE (125 * SHARP_UNIT) /* 5 ms (even longer) */
enum sharp_state {
STATE_INACTIVE,
STATE_BIT_PULSE,
STATE_BIT_SPACE,
STATE_TRAILER_PULSE,
STATE_ECHO_SPACE,
STATE_TRAILER_SPACE,
};
/**
* ir_sharp_decode() - Decode one Sharp 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_sharp_decode(struct rc_dev *dev, struct ir_raw_event ev)
{
struct sharp_dec *data = &dev->raw->sharp;
u32 msg, echo, address, command, scancode;
if (!is_timing_event(ev)) {
if (ev.reset)
data->state = STATE_INACTIVE;
return 0;
}
dev_dbg(&dev->dev, "Sharp decode started at state %d (%uus %s)\n",
data->state, ev.duration, TO_STR(ev.pulse));
switch (data->state) {
case STATE_INACTIVE:
if (!ev.pulse)
break;
if (!eq_margin(ev.duration, SHARP_BIT_PULSE,
SHARP_BIT_PULSE / 2))
break;
data->count = 0;
data->pulse_len = ev.duration;
data->state = STATE_BIT_SPACE;
return 0;
case STATE_BIT_PULSE:
if (!ev.pulse)
break;
if (!eq_margin(ev.duration, SHARP_BIT_PULSE,
SHARP_BIT_PULSE / 2))
break;
data->pulse_len = ev.duration;
data->state = STATE_BIT_SPACE;
return 0;
case STATE_BIT_SPACE:
if (ev.pulse)
break;
data->bits <<= 1;
if (eq_margin(data->pulse_len + ev.duration, SHARP_BIT_1_PERIOD,
SHARP_BIT_PULSE * 2))
data->bits |= 1;
else if (!eq_margin(data->pulse_len + ev.duration,
SHARP_BIT_0_PERIOD, SHARP_BIT_PULSE * 2))
break;
data->count++;
if (data->count == SHARP_NBITS ||
data->count == SHARP_NBITS * 2)
data->state = STATE_TRAILER_PULSE;
else
data->state = STATE_BIT_PULSE;
return 0;
case STATE_TRAILER_PULSE:
if (!ev.pulse)
break;
if (!eq_margin(ev.duration, SHARP_BIT_PULSE,
SHARP_BIT_PULSE / 2))
break;
if (data->count == SHARP_NBITS) {
/* exp,chk bits should be 1,0 */
if ((data->bits & 0x3) != 0x2 &&
/* DENON variant, both chk bits 0 */
(data->bits & 0x3) != 0x0)
break;
data->state = STATE_ECHO_SPACE;
} else {
data->state = STATE_TRAILER_SPACE;
}
return 0;
case STATE_ECHO_SPACE:
if (ev.pulse)
break;
if (!eq_margin(ev.duration, SHARP_ECHO_SPACE,
SHARP_ECHO_SPACE / 4))
break;
data->state = STATE_BIT_PULSE;
return 0;
case STATE_TRAILER_SPACE:
if (ev.pulse)
break;
if (!geq_margin(ev.duration, SHARP_TRAILER_SPACE,
SHARP_BIT_PULSE / 2))
break;
/* Validate - command, ext, chk should be inverted in 2nd */
msg = (data->bits >> 15) & 0x7fff;
echo = data->bits & 0x7fff;
if ((msg ^ echo) != 0x3ff) {
dev_dbg(&dev->dev,
"Sharp checksum error: received 0x%04x, 0x%04x\n",
msg, echo);
break;
}
address = bitrev8((msg >> 7) & 0xf8);
command = bitrev8((msg >> 2) & 0xff);
scancode = address << 8 | command;
dev_dbg(&dev->dev, "Sharp scancode 0x%04x\n", scancode);
rc_keydown(dev, RC_PROTO_SHARP, scancode, 0);
data->state = STATE_INACTIVE;
return 0;
}
dev_dbg(&dev->dev, "Sharp 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 const struct ir_raw_timings_pd ir_sharp_timings = {
.header_pulse = 0,
.header_space = 0,
.bit_pulse = SHARP_BIT_PULSE,
.bit_space[0] = SHARP_BIT_0_PERIOD,
.bit_space[1] = SHARP_BIT_1_PERIOD,
.trailer_pulse = SHARP_BIT_PULSE,
.trailer_space = SHARP_ECHO_SPACE,
.msb_first = 1,
};
/**
* ir_sharp_encode() - Encode a scancode as a stream of raw events
*
* @protocol: protocol to encode
* @scancode: scancode to encode
* @events: array of raw ir events to write into
* @max: maximum size of @events
*
* Returns: The number of events written.
* -ENOBUFS if there isn't enough space in the array to fit the
* encoding. In this case all @max events will have been written.
*/
static int ir_sharp_encode(enum rc_proto protocol, u32 scancode,
struct ir_raw_event *events, unsigned int max)
{
struct ir_raw_event *e = events;
int ret;
u32 raw;
raw = (((bitrev8(scancode >> 8) >> 3) << 8) & 0x1f00) |
bitrev8(scancode);
ret = ir_raw_gen_pd(&e, max, &ir_sharp_timings, SHARP_NBITS,
(raw << 2) | 2);
if (ret < 0)
return ret;
max -= ret;
raw = (((bitrev8(scancode >> 8) >> 3) << 8) & 0x1f00) |
bitrev8(~scancode);
ret = ir_raw_gen_pd(&e, max, &ir_sharp_timings, SHARP_NBITS,
(raw << 2) | 1);
if (ret < 0)
return ret;
return e - events;
}
static struct ir_raw_handler sharp_handler = {
.protocols = RC_PROTO_BIT_SHARP,
.decode = ir_sharp_decode,
.encode = ir_sharp_encode,
.carrier = 38000,
.min_timeout = SHARP_ECHO_SPACE + SHARP_ECHO_SPACE / 4,
};
static int __init ir_sharp_decode_init(void)
{
ir_raw_handler_register(&sharp_handler);
pr_info("IR Sharp protocol handler initialized\n");
return 0;
}
static void __exit ir_sharp_decode_exit(void)
{
ir_raw_handler_unregister(&sharp_handler);
}
module_init(ir_sharp_decode_init);
module_exit(ir_sharp_decode_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("James Hogan <jhogan@kernel.org>");
MODULE_DESCRIPTION("Sharp IR protocol decoder");