linux/drivers/media/IR/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 <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.
*/
#include <media/ir-core.h>
#define NEC_NBITS 32
#define NEC_UNIT 559979 /* ns */
#define NEC_HEADER_MARK (16 * NEC_UNIT)
#define NEC_HEADER_SPACE (8 * NEC_UNIT)
#define NEC_REPEAT_SPACE (4 * NEC_UNIT)
#define NEC_MARK (NEC_UNIT)
#define NEC_0_SPACE (NEC_UNIT)
#define NEC_1_SPACE (3 * NEC_UNIT)
/* Used to register nec_decoder clients */
static LIST_HEAD(decoder_list);
static spinlock_t decoder_lock;
enum nec_state {
STATE_INACTIVE,
STATE_HEADER_MARK,
STATE_HEADER_SPACE,
STATE_MARK,
STATE_SPACE,
STATE_TRAILER_MARK,
STATE_TRAILER_SPACE,
};
struct nec_code {
u8 address;
u8 not_address;
u8 command;
u8 not_command;
};
struct decoder_data {
struct list_head list;
struct ir_input_dev *ir_dev;
int enabled:1;
/* State machine control */
enum nec_state state;
struct nec_code nec_code;
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 = "nec_decoder",
.attrs = decoder_attributes,
};
/**
* handle_event() - Decode one NEC pulse or space
* @input_dev: the struct input_dev descriptor of the device
* @ev: event array with type/duration of pulse/space
*
* This function returns -EINVAL if the pulse violates the state machine
*/
static int handle_event(struct input_dev *input_dev,
struct ir_raw_event *ev)
{
struct decoder_data *data;
struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
int bit, last_bit;
data = get_decoder_data(ir_dev);
if (!data)
return -EINVAL;
/* Except for the initial event, what matters is the previous bit */
bit = (ev->type & IR_PULSE) ? 1 : 0;
last_bit = !bit;
/* Discards spurious space last_bits when inactive */
/* Very long delays are considered as start events */
if (ev->delta.tv_nsec > NEC_HEADER_MARK + NEC_HEADER_SPACE - NEC_UNIT / 2)
data->state = STATE_INACTIVE;
if (ev->type & IR_START_EVENT)
data->state = STATE_INACTIVE;
switch (data->state) {
case STATE_INACTIVE:
if (!bit) /* PULSE marks the start event */
return 0;
data->count = 0;
data->state = STATE_HEADER_MARK;
memset (&data->nec_code, 0, sizeof(data->nec_code));
return 0;
case STATE_HEADER_MARK:
if (!last_bit)
goto err;
if (ev->delta.tv_nsec < NEC_HEADER_MARK - 6 * NEC_UNIT)
goto err;
data->state = STATE_HEADER_SPACE;
return 0;
case STATE_HEADER_SPACE:
if (last_bit)
goto err;
if (ev->delta.tv_nsec >= NEC_HEADER_SPACE - NEC_UNIT / 2) {
data->state = STATE_MARK;
return 0;
}
if (ev->delta.tv_nsec >= NEC_REPEAT_SPACE - NEC_UNIT / 2) {
ir_repeat(input_dev);
IR_dprintk(1, "Repeat last key\n");
data->state = STATE_TRAILER_MARK;
return 0;
}
goto err;
case STATE_MARK:
if (!last_bit)
goto err;
if ((ev->delta.tv_nsec > NEC_MARK + NEC_UNIT / 2) ||
(ev->delta.tv_nsec < NEC_MARK - NEC_UNIT / 2))
goto err;
data->state = STATE_SPACE;
return 0;
case STATE_SPACE:
if (last_bit)
goto err;
if ((ev->delta.tv_nsec >= NEC_0_SPACE - NEC_UNIT / 2) &&
(ev->delta.tv_nsec < NEC_0_SPACE + NEC_UNIT / 2))
bit = 0;
else if ((ev->delta.tv_nsec >= NEC_1_SPACE - NEC_UNIT / 2) &&
(ev->delta.tv_nsec < NEC_1_SPACE + NEC_UNIT / 2))
bit = 1;
else {
IR_dprintk(1, "Decode failed at %d-th bit (%s) @%luus\n",
data->count,
last_bit ? "pulse" : "space",
(ev->delta.tv_nsec + 500) / 1000);
goto err2;
}
/* Ok, we've got a valid bit. proccess it */
if (bit) {
int shift = data->count;
/*
* NEC transmit bytes on this temporal order:
* address | not address | command | not command
*/
if (shift < 8) {
data->nec_code.address |= 1 << shift;
} else if (shift < 16) {
data->nec_code.not_address |= 1 << (shift - 8);
} else if (shift < 24) {
data->nec_code.command |= 1 << (shift - 16);
} else {
data->nec_code.not_command |= 1 << (shift - 24);
}
}
if (++data->count == NEC_NBITS) {
u32 scancode;
/*
* Fixme: may need to accept Extended NEC protocol?
*/
if ((data->nec_code.command ^ data->nec_code.not_command) != 0xff)
goto checksum_err;
if ((data->nec_code.address ^ data->nec_code.not_address) != 0xff) {
/* Extended NEC */
scancode = data->nec_code.address << 16 |
data->nec_code.not_address << 8 |
data->nec_code.command;
IR_dprintk(1, "NEC scancode 0x%06x\n", scancode);
} else {
/* normal NEC */
scancode = data->nec_code.address << 8 |
data->nec_code.command;
IR_dprintk(1, "NEC scancode 0x%04x\n", scancode);
}
ir_keydown(input_dev, scancode, 0);
data->state = STATE_TRAILER_MARK;
} else
data->state = STATE_MARK;
return 0;
case STATE_TRAILER_MARK:
if (!last_bit)
goto err;
data->state = STATE_TRAILER_SPACE;
return 0;
case STATE_TRAILER_SPACE:
if (last_bit)
goto err;
data->state = STATE_INACTIVE;
return 0;
}
err:
IR_dprintk(1, "NEC decoded failed at state %d (%s) @ %luus\n",
data->state,
bit ? "pulse" : "space",
(ev->delta.tv_nsec + 500) / 1000);
err2:
data->state = STATE_INACTIVE;
return -EINVAL;
checksum_err:
data->state = STATE_INACTIVE;
IR_dprintk(1, "NEC checksum error: received 0x%02x%02x%02x%02x\n",
data->nec_code.address,
data->nec_code.not_address,
data->nec_code.command,
data->nec_code.not_command);
return -EINVAL;
}
/**
* ir_nec_decode() - Decodes all NEC pulsecodes on a given array
* @input_dev: the struct input_dev descriptor of the device
* @evs: event array with type/duration of pulse/space
* @len: length of the array
* This function returns the number of decoded pulses
*/
static int ir_nec_decode(struct input_dev *input_dev,
struct ir_raw_event *evs,
int len)
{
struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
struct decoder_data *data;
int pos = 0;
int rc = 0;
data = get_decoder_data(ir_dev);
if (!data || !data->enabled)
return 0;
for (pos = 0; pos < len; pos++)
handle_event(input_dev, &evs[pos]);
return rc;
}
static int ir_nec_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_nec_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 nec_handler = {
.decode = ir_nec_decode,
.raw_register = ir_nec_register,
.raw_unregister = ir_nec_unregister,
};
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 <mchehab@redhat.com>");
MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
MODULE_DESCRIPTION("NEC IR protocol decoder");