linux-hardened/drivers/media/IR/ir-rc5-decoder.c
David Härdeman 724e249550 V4L/DVB: Teach drivers/media/IR/ir-raw-event.c to use durations
drivers/media/IR/ir-raw-event.c is currently written with the assumption
that all "raw" hardware will generate events only on state change (i.e.
when a pulse or space starts).

However, some hardware (like mceusb, probably the most popular IR receiver
out there) only generates duration data (and that data is buffered so using
any kind of timing on the data is futile).

Furthermore, using signed int's to represent pulse/space durations is a
well-known approach when writing ir decoders.

With this patch:

- s64 int's are used to represent pulse/space durations in ns

- a workqueue is used to decode the ir protocols outside of interrupt context

- #defines are added to make decoders clearer

- decoder reset is implemented by passing a zero duration to the kfifo queue
  and decoders are updated accordingly

Signed-off-by: David Härdeman <david@hardeman.nu>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2010-05-19 12:57:03 -03:00

291 lines
6.6 KiB
C

/* ir-rc5-decoder.c - handle RC-5 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 only handles 14 bits RC-5 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 bits, where
* the first two bits are start bits, and a third one is a filing bit
*/
#include <media/ir-core.h>
#define RC5_NBITS 14
#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_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;
};
/**
* 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 command, system, 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 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;
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 == RC5_NBITS) {
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 == RC5_NBITS)
data->state = STATE_FINISHED;
else
data->state = STATE_BIT_START;
DECREASE_DURATION(u, 1);
goto again;
}
break;
case STATE_FINISHED:
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 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 RC-5 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("RC-5 IR protocol decoder");