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/* ir-rc5-decoder.c - handle RC5(x) 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.
*/
/*
* This code handles 14 bits RC5 protocols and 20 bits RC5x protocols.
* There are other variants that use a different number of bits.
* This is currently unsupported.
* It considers a carrier of 36 kHz, with a total of 14/20 bits, where
* the first two bits are start bits, and a third one is a filing bit
*/
#include "ir-core-priv.h"
#define RC5_NBITS 14
#define RC5X_NBITS 20
#define CHECK_RC5X_NBITS 8
#define RC5X_SPACE SPACE(4)
#define RC5_UNIT 888888 /* ns */
/* Used to register rc5_decoder clients */
static LIST_HEAD(decoder_list);
static DEFINE_SPINLOCK(decoder_lock);
enum rc5_state {
STATE_INACTIVE,
STATE_BIT_START,
STATE_BIT_END,
STATE_CHECK_RC5X,
STATE_FINISHED,
};
struct decoder_data {
struct list_head list;
struct ir_input_dev *ir_dev;
int enabled:1;
/* State machine control */
enum rc5_state state;
u32 rc5_bits;
int last_unit;
unsigned count;
unsigned wanted_bits;
};
/**
* get_decoder_data() - gets decoder data
* @input_dev: input device
*
* Returns the struct decoder_data that corresponds to a device
*/
static struct decoder_data *get_decoder_data(struct ir_input_dev *ir_dev)
{
struct decoder_data *data = NULL;
spin_lock(&decoder_lock);
list_for_each_entry(data, &decoder_list, list) {
if (data->ir_dev == ir_dev)
break;
}
spin_unlock(&decoder_lock);
return data;
}
static ssize_t store_enabled(struct device *d,
struct device_attribute *mattr,
const char *buf,
size_t len)
{
unsigned long value;
struct ir_input_dev *ir_dev = dev_get_drvdata(d);
struct decoder_data *data = get_decoder_data(ir_dev);
if (!data)
return -EINVAL;
if (strict_strtoul(buf, 10, &value) || value > 1)
return -EINVAL;
data->enabled = value;
return len;
}
static ssize_t show_enabled(struct device *d,
struct device_attribute *mattr, char *buf)
{
struct ir_input_dev *ir_dev = dev_get_drvdata(d);
struct decoder_data *data = get_decoder_data(ir_dev);
if (!data)
return -EINVAL;
if (data->enabled)
return sprintf(buf, "1\n");
else
return sprintf(buf, "0\n");
}
static DEVICE_ATTR(enabled, S_IRUGO | S_IWUSR, show_enabled, store_enabled);
static struct attribute *decoder_attributes[] = {
&dev_attr_enabled.attr,
NULL
};
static struct attribute_group decoder_attribute_group = {
.name = "rc5_decoder",
.attrs = decoder_attributes,
};
/**
* ir_rc5_decode() - Decode one RC-5 pulse or space
* @input_dev: the struct input_dev descriptor of the device
* @duration: duration of pulse/space in ns
*
* This function returns -EINVAL if the pulse violates the state machine
*/
static int ir_rc5_decode(struct input_dev *input_dev, s64 duration)
{
struct decoder_data *data;
struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
u8 toggle;
u32 scancode;
int u;
data = get_decoder_data(ir_dev);
if (!data)
return -EINVAL;
if (!data->enabled)
return 0;
if (IS_RESET(duration)) {
data->state = STATE_INACTIVE;
return 0;
}
u = TO_UNITS(duration, RC5_UNIT);
if (DURATION(u) == 0)
goto out;
again:
IR_dprintk(2, "RC5(x) decode started at state %i (%i units, %ius)\n",
data->state, u, TO_US(duration));
if (DURATION(u) == 0 && data->state != STATE_FINISHED)
return 0;
switch (data->state) {
case STATE_INACTIVE:
if (IS_PULSE(u)) {
data->state = STATE_BIT_START;
data->count = 1;
/* We just need enough bits to get to STATE_CHECK_RC5X */
data->wanted_bits = RC5X_NBITS;
DECREASE_DURATION(u, 1);
goto again;
}
break;
case STATE_BIT_START:
if (DURATION(u) == 1) {
data->rc5_bits <<= 1;
if (IS_SPACE(u))
data->rc5_bits |= 1;
data->count++;
data->last_unit = u;
/*
* If the last bit is zero, a space will merge
* with the silence after the command.
*/
if (IS_PULSE(u) && data->count == data->wanted_bits) {
data->state = STATE_FINISHED;
goto again;
}
data->state = STATE_BIT_END;
return 0;
}
break;
case STATE_BIT_END:
if (IS_TRANSITION(u, data->last_unit)) {
if (data->count == data->wanted_bits)
data->state = STATE_FINISHED;
else if (data->count == CHECK_RC5X_NBITS)
data->state = STATE_CHECK_RC5X;
else
data->state = STATE_BIT_START;
DECREASE_DURATION(u, 1);
goto again;
}
break;
case STATE_CHECK_RC5X:
if (IS_SPACE(u) && DURATION(u) >= DURATION(RC5X_SPACE)) {
/* RC5X */
data->wanted_bits = RC5X_NBITS;
DECREASE_DURATION(u, DURATION(RC5X_SPACE));
} else {
/* RC5 */
data->wanted_bits = RC5_NBITS;
}
data->state = STATE_BIT_START;
goto again;
case STATE_FINISHED:
if (data->wanted_bits == RC5X_NBITS) {
/* RC5X */
u8 xdata, command, system;
xdata = (data->rc5_bits & 0x0003F) >> 0;
command = (data->rc5_bits & 0x00FC0) >> 6;
system = (data->rc5_bits & 0x1F000) >> 12;
toggle = (data->rc5_bits & 0x20000) ? 1 : 0;
command += (data->rc5_bits & 0x01000) ? 0 : 0x40;
scancode = system << 16 | command << 8 | xdata;
IR_dprintk(1, "RC5X scancode 0x%06x (toggle: %u)\n",
scancode, toggle);
} else {
/* RC5 */
u8 command, system;
command = (data->rc5_bits & 0x0003F) >> 0;
system = (data->rc5_bits & 0x007C0) >> 6;
toggle = (data->rc5_bits & 0x00800) ? 1 : 0;
command += (data->rc5_bits & 0x01000) ? 0 : 0x40;
scancode = system << 8 | command;
IR_dprintk(1, "RC5 scancode 0x%04x (toggle: %u)\n",
scancode, toggle);
}
ir_keydown(input_dev, scancode, toggle);
data->state = STATE_INACTIVE;
return 0;
}
out:
IR_dprintk(1, "RC5(x) decode failed at state %i (%i units, %ius)\n",
data->state, u, TO_US(duration));
data->state = STATE_INACTIVE;
return -EINVAL;
}
static int ir_rc5_register(struct input_dev *input_dev)
{
struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
struct decoder_data *data;
int rc;
rc = sysfs_create_group(&ir_dev->dev.kobj, &decoder_attribute_group);
if (rc < 0)
return rc;
data = kzalloc(sizeof(*data), GFP_KERNEL);
if (!data) {
sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);
return -ENOMEM;
}
data->ir_dev = ir_dev;
data->enabled = 1;
spin_lock(&decoder_lock);
list_add_tail(&data->list, &decoder_list);
spin_unlock(&decoder_lock);
return 0;
}
static int ir_rc5_unregister(struct input_dev *input_dev)
{
struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
static struct decoder_data *data;
data = get_decoder_data(ir_dev);
if (!data)
return 0;
sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);
spin_lock(&decoder_lock);
list_del(&data->list);
spin_unlock(&decoder_lock);
return 0;
}
static struct ir_raw_handler rc5_handler = {
.decode = ir_rc5_decode,
.raw_register = ir_rc5_register,
.raw_unregister = ir_rc5_unregister,
};
static int __init ir_rc5_decode_init(void)
{
ir_raw_handler_register(&rc5_handler);
printk(KERN_INFO "IR RC5(x) protocol handler initialized\n");
return 0;
}
static void __exit ir_rc5_decode_exit(void)
{
ir_raw_handler_unregister(&rc5_handler);
}
module_init(ir_rc5_decode_init);
module_exit(ir_rc5_decode_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@redhat.com>");
MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
MODULE_DESCRIPTION("RC5(x) IR protocol decoder");
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