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linux_old1/drivers/media/rc/ir-nec-decoder.c

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/* ir-nec-decoder.c - handle NEC IR Pulse/Space protocol
*
* Copyright (C) 2010 by Mauro Carvalho Chehab
*
* 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 <linux/bitrev.h>
#include <linux/module.h>
#include "rc-core-priv.h"
#define NEC_NBITS 32
#define NEC_UNIT 562500 /* ns */
#define NEC_HEADER_PULSE (16 * NEC_UNIT)
#define NECX_HEADER_PULSE (8 * NEC_UNIT) /* Less common NEC variant */
#define NEC_HEADER_SPACE (8 * NEC_UNIT)
#define NEC_REPEAT_SPACE (4 * NEC_UNIT)
#define NEC_BIT_PULSE (1 * NEC_UNIT)
#define NEC_BIT_0_SPACE (1 * NEC_UNIT)
#define NEC_BIT_1_SPACE (3 * NEC_UNIT)
#define NEC_TRAILER_PULSE (1 * NEC_UNIT)
#define NEC_TRAILER_SPACE (10 * NEC_UNIT) /* even longer in reality */
#define NECX_REPEAT_BITS 1
enum nec_state {
STATE_INACTIVE,
STATE_HEADER_SPACE,
STATE_BIT_PULSE,
STATE_BIT_SPACE,
STATE_TRAILER_PULSE,
STATE_TRAILER_SPACE,
};
/**
* ir_nec_decode() - Decode one NEC pulse or space
* @dev: the struct rc_dev descriptor of the device
* @duration: the struct ir_raw_event descriptor of the pulse/space
*
* This function returns -EINVAL if the pulse violates the state machine
*/
static int ir_nec_decode(struct rc_dev *dev, struct ir_raw_event ev)
{
struct nec_dec *data = &dev->raw->nec;
u32 scancode;
enum rc_type rc_type;
u8 address, not_address, command, not_command;
bool send_32bits = false;
if (!is_timing_event(ev)) {
if (ev.reset)
data->state = STATE_INACTIVE;
return 0;
}
IR_dprintk(2, "NEC decode started at state %d (%uus %s)\n",
data->state, TO_US(ev.duration), TO_STR(ev.pulse));
switch (data->state) {
case STATE_INACTIVE:
if (!ev.pulse)
break;
if (eq_margin(ev.duration, NEC_HEADER_PULSE, NEC_UNIT * 2)) {
data->is_nec_x = false;
data->necx_repeat = false;
} else if (eq_margin(ev.duration, NECX_HEADER_PULSE, NEC_UNIT / 2))
data->is_nec_x = true;
else
break;
data->count = 0;
data->state = STATE_HEADER_SPACE;
return 0;
case STATE_HEADER_SPACE:
if (ev.pulse)
break;
if (eq_margin(ev.duration, NEC_HEADER_SPACE, NEC_UNIT)) {
data->state = STATE_BIT_PULSE;
return 0;
} else if (eq_margin(ev.duration, NEC_REPEAT_SPACE, NEC_UNIT / 2)) {
if (!dev->keypressed) {
IR_dprintk(1, "Discarding last key repeat: event after key up\n");
} else {
rc_repeat(dev);
IR_dprintk(1, "Repeat last key\n");
data->state = STATE_TRAILER_PULSE;
}
return 0;
}
break;
case STATE_BIT_PULSE:
if (!ev.pulse)
break;
if (!eq_margin(ev.duration, NEC_BIT_PULSE, NEC_UNIT / 2))
break;
data->state = STATE_BIT_SPACE;
return 0;
case STATE_BIT_SPACE:
if (ev.pulse)
break;
if (data->necx_repeat && data->count == NECX_REPEAT_BITS &&
geq_margin(ev.duration,
NEC_TRAILER_SPACE, NEC_UNIT / 2)) {
IR_dprintk(1, "Repeat last key\n");
rc_repeat(dev);
data->state = STATE_INACTIVE;
return 0;
} else if (data->count > NECX_REPEAT_BITS)
data->necx_repeat = false;
data->bits <<= 1;
if (eq_margin(ev.duration, NEC_BIT_1_SPACE, NEC_UNIT / 2))
data->bits |= 1;
else if (!eq_margin(ev.duration, NEC_BIT_0_SPACE, NEC_UNIT / 2))
break;
data->count++;
if (data->count == NEC_NBITS)
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, NEC_TRAILER_PULSE, NEC_UNIT / 2))
break;
data->state = STATE_TRAILER_SPACE;
return 0;
case STATE_TRAILER_SPACE:
if (ev.pulse)
break;
if (!geq_margin(ev.duration, NEC_TRAILER_SPACE, NEC_UNIT / 2))
break;
address = bitrev8((data->bits >> 24) & 0xff);
not_address = bitrev8((data->bits >> 16) & 0xff);
command = bitrev8((data->bits >> 8) & 0xff);
not_command = bitrev8((data->bits >> 0) & 0xff);
if ((command ^ not_command) != 0xff) {
IR_dprintk(1, "NEC checksum error: received 0x%08x\n",
data->bits);
send_32bits = true;
}
if (send_32bits) {
/* NEC transport, but modified protocol, used by at
* least Apple and TiVo remotes */
scancode = not_address << 24 |
address << 16 |
not_command << 8 |
command;
IR_dprintk(1, "NEC (modified) scancode 0x%08x\n", scancode);
rc_type = RC_TYPE_NEC32;
} else if ((address ^ not_address) != 0xff) {
/* Extended NEC */
scancode = address << 16 |
not_address << 8 |
command;
IR_dprintk(1, "NEC (Ext) scancode 0x%06x\n", scancode);
rc_type = RC_TYPE_NECX;
} else {
/* Normal NEC */
scancode = address << 8 | command;
IR_dprintk(1, "NEC scancode 0x%04x\n", scancode);
rc_type = RC_TYPE_NEC;
}
if (data->is_nec_x)
data->necx_repeat = true;
rc_keydown(dev, rc_type, scancode, 0);
data->state = STATE_INACTIVE;
return 0;
}
IR_dprintk(1, "NEC decode failed at count %d state %d (%uus %s)\n",
data->count, data->state, TO_US(ev.duration), TO_STR(ev.pulse));
data->state = STATE_INACTIVE;
return -EINVAL;
}
/**
* ir_nec_scancode_to_raw() - encode an NEC scancode ready for modulation.
* @protocol: specific protocol to use
* @scancode: a single NEC scancode.
* @raw: raw data to be modulated.
*/
static u32 ir_nec_scancode_to_raw(enum rc_type protocol, u32 scancode)
{
unsigned int addr, addr_inv, data, data_inv;
data = scancode & 0xff;
if (protocol == RC_TYPE_NEC32) {
/* 32-bit NEC (used by Apple and TiVo remotes) */
/* scan encoding: aaAAddDD */
addr_inv = (scancode >> 24) & 0xff;
addr = (scancode >> 16) & 0xff;
data_inv = (scancode >> 8) & 0xff;
} else if (protocol == RC_TYPE_NECX) {
/* Extended NEC */
/* scan encoding AAaaDD */
addr = (scancode >> 16) & 0xff;
addr_inv = (scancode >> 8) & 0xff;
data_inv = data ^ 0xff;
} else {
/* Normal NEC */
/* scan encoding: AADD */
addr = (scancode >> 8) & 0xff;
addr_inv = addr ^ 0xff;
data_inv = data ^ 0xff;
}
/* raw encoding: ddDDaaAA */
return data_inv << 24 |
data << 16 |
addr_inv << 8 |
addr;
}
static const struct ir_raw_timings_pd ir_nec_timings = {
.header_pulse = NEC_HEADER_PULSE,
.header_space = NEC_HEADER_SPACE,
.bit_pulse = NEC_BIT_PULSE,
.bit_space[0] = NEC_BIT_0_SPACE,
.bit_space[1] = NEC_BIT_1_SPACE,
.trailer_pulse = NEC_TRAILER_PULSE,
.trailer_space = NEC_TRAILER_SPACE,
.msb_first = 0,
};
/**
* ir_nec_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_nec_encode(enum rc_type protocol, u32 scancode,
struct ir_raw_event *events, unsigned int max)
{
struct ir_raw_event *e = events;
int ret;
u32 raw;
/* Convert a NEC scancode to raw NEC data */
raw = ir_nec_scancode_to_raw(protocol, scancode);
/* Modulate the raw data using a pulse distance modulation */
ret = ir_raw_gen_pd(&e, max, &ir_nec_timings, NEC_NBITS, raw);
if (ret < 0)
return ret;
return e - events;
}
static struct ir_raw_handler nec_handler = {
.protocols = RC_BIT_NEC | RC_BIT_NECX | RC_BIT_NEC32,
.decode = ir_nec_decode,
.encode = ir_nec_encode,
};
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");
MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
MODULE_DESCRIPTION("NEC IR protocol decoder");
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