ardupilot/libraries/AP_HAL_Linux/Led_Sysfs.cpp

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/*
Copyright (C) 2017 Mathieu Othacehe. All rights reserved.
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, either version 3 of the License, or
(at your option) any later version.
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.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "Led_Sysfs.h"
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <AP_HAL/AP_HAL.h>
extern const AP_HAL::HAL& hal;
namespace Linux {
Led_Sysfs::Led_Sysfs(const char *led_name)
: _led_name(led_name)
{
}
Led_Sysfs::~Led_Sysfs()
{
if (_brightness_fd >= 0) {
close(_brightness_fd);
}
}
bool Led_Sysfs::init()
{
char *br_path;
char *max_br_path;
if (asprintf(&br_path, "/sys/class/leds/%s/brightness", _led_name) == -1) {
AP_HAL::panic("LinuxLed_Sysfs : Couldn't allocate brightness path");
}
_brightness_fd = open(br_path, O_WRONLY | O_CLOEXEC);
if (_brightness_fd < 0) {
printf("LinuxLed_Sysfs: Unable to open file %s\n", br_path);
free(br_path);
return false;
}
if (asprintf(&max_br_path, "/sys/class/leds/%s/max_brightness", _led_name) == -1) {
AP_HAL::panic("LinuxLed_Sysfs : Couldn't allocate max_brightness path");
}
if (Util::from(hal.util)->read_file(max_br_path, "%u", &_max_brightness) < 0) {
AP_HAL::panic("LinuxLed_Sysfs : Unable to read max_brightness in %s",
max_br_path);
}
free(max_br_path);
free(br_path);
return true;
}
bool Led_Sysfs::set_brightness(uint8_t brightness)
{
if (_brightness_fd < 0) {
return false;
}
unsigned int br = brightness * _max_brightness / UINT8_MAX;
/* Don't log fails since this could spam the console */
if (dprintf(_brightness_fd, "%u", br) < 0) {
return false;
}
return true;
}
}