mraa/src/led/led.c

/*
 * Author: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
 * Copyright (c) 2017 Linaro Ltd.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include "led.h"
#include "mraa_internal.h"

#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdlib.h>
#include <string.h>
#include <sys/errno.h>
#include <sys/stat.h>
#include <unistd.h>

#define SYSFS_CLASS_LED "/sys/class/leds"
#define MAX_SIZE 64

static mraa_result_t
mraa_led_get_trigfd(mraa_led_context dev)
{
    char buf[MAX_SIZE];

    snprintf(buf, MAX_SIZE, "%s/%s", dev->led_path, "trigger");
    dev->trig_fd = open(buf, O_RDWR);
    if (dev->trig_fd == -1) {
        syslog(LOG_ERR, "led: trigger: Failed to open 'trigger': %s", strerror(errno));
        return MRAA_ERROR_INVALID_RESOURCE;
    }

    return MRAA_SUCCESS;
}

static mraa_result_t
mraa_led_get_brightfd(mraa_led_context dev)
{
    char buf[MAX_SIZE];

    snprintf(buf, MAX_SIZE, "%s/%s", dev->led_path, "brightness");
    dev->bright_fd = open(buf, O_RDWR);
    if (dev->bright_fd == -1) {
        syslog(LOG_ERR, "led: brightness: Failed to open 'brightness': %s", strerror(errno));
        return MRAA_ERROR_INVALID_RESOURCE;
    }

    return MRAA_SUCCESS;
}

static mraa_result_t
mraa_led_get_maxbrightfd(mraa_led_context dev)
{
    char buf[MAX_SIZE];

    snprintf(buf, MAX_SIZE, "%s/%s", dev->led_path, "max_brightness");
    dev->max_bright_fd = open(buf, O_RDONLY);
    if (dev->max_bright_fd == -1) {
        syslog(LOG_ERR, "led: max_brightness: Failed to open 'max_brightness': %s", strerror(errno));
        return MRAA_ERROR_INVALID_RESOURCE;
    }

    return MRAA_SUCCESS;
}

static mraa_led_context
mraa_led_init_internal(const char* led)
{
    DIR* dir;
    struct dirent* entry;
    int cnt = 0;

    mraa_led_context dev = (mraa_led_context) calloc(1, sizeof(struct _led));
    if (dev == NULL) {
        syslog(LOG_CRIT, "led: init: Failed to allocate memory for context");
        return NULL;
    }

    dev->led_name = NULL;
    dev->trig_fd = -1;
    dev->bright_fd = -1;
    dev->max_bright_fd = -1;

    if ((dir = opendir(SYSFS_CLASS_LED)) != NULL) {
        /* get the led name from sysfs path */
        while ((entry = readdir(dir)) != NULL) {
            if (strstr((const char*) entry->d_name, led)) {
                dev->led_name = (char*) entry->d_name;
            }
            cnt++;
        }
    }
    dev->count = cnt;
    if (dev->led_name == NULL) {
        syslog(LOG_CRIT, "led: init: unknown device specified");
        if (dir != NULL) {
            closedir(dir);
        }
        free(dev);
        return NULL;
    }

    if (dir != NULL) {
        closedir(dir);
    }
    return dev;
}

mraa_led_context
mraa_led_init(const char* led)
{
    mraa_led_context dev = NULL;
    char directory[MAX_SIZE];
    struct stat dir;

    if (plat == NULL) {
        syslog(LOG_ERR, "led: init: platform not initialised");
        return NULL;
    }

    if (led == NULL) {
        syslog(LOG_ERR, "led: init: invalid device specified");
        return NULL;
    }

    dev = mraa_led_init_internal(led);
    if (dev == NULL) {
        return NULL;
    }

    snprintf(directory, MAX_SIZE, "%s/%s", SYSFS_CLASS_LED, dev->led_name);
    if (stat(directory, &dir) == 0 && S_ISDIR(dir.st_mode)) {
        syslog(LOG_NOTICE, "led: init: current user don't have access rights for using LED %s", dev->led_name);
    }
    strncpy(dev->led_path, (const char*) directory, sizeof(directory));

    return dev;
}

mraa_result_t
mraa_led_set_brightness(mraa_led_context dev, int value)
{
    char buf[MAX_SIZE];
    int length;

    if (dev == NULL) {
        syslog(LOG_ERR, "led: set_brightness: context is invalid");
        return MRAA_ERROR_INVALID_HANDLE;
    }

    if (dev->trig_fd != -1) {
        close(dev->trig_fd);
        dev->trig_fd = -1;
    }

    if (dev->max_bright_fd != -1) {
        close(dev->max_bright_fd);
        dev->max_bright_fd = -1;
    }

    if (dev->bright_fd == -1) {
        if (mraa_led_get_brightfd(dev) != MRAA_SUCCESS) {
            return MRAA_ERROR_INVALID_RESOURCE;
        }
    }

    if (lseek(dev->bright_fd, 0, SEEK_SET) == -1) {
        syslog(LOG_ERR, "led: set_brightness: Failed to lseek 'brightness': %s", strerror(errno));
        return MRAA_ERROR_UNSPECIFIED;
    }

    length = snprintf(buf, sizeof(buf), "%d", value);
    if (write(dev->bright_fd, buf, length * sizeof(char)) == -1) {
        syslog(LOG_ERR, "led: set_brightness: Failed to write 'brightness': %s", strerror(errno));
        return MRAA_ERROR_UNSPECIFIED;
    }

    return MRAA_SUCCESS;
}

int
mraa_led_read_brightness(mraa_led_context dev)
{
    char buf[3];

    if (dev == NULL) {
        syslog(LOG_ERR, "led: read_brightness: context is invalid");
        return MRAA_ERROR_INVALID_HANDLE;
    }

    if (dev->trig_fd != -1) {
        close(dev->trig_fd);
        dev->trig_fd = -1;
    }

    if (dev->max_bright_fd != -1) {
        close(dev->max_bright_fd);
        dev->max_bright_fd = -1;
    }

    if (dev->bright_fd == -1) {
        if (mraa_led_get_brightfd(dev) != MRAA_SUCCESS) {
            return MRAA_ERROR_INVALID_RESOURCE;
        }
    } else {
        lseek(dev->bright_fd, 0, SEEK_SET);
    }

    if (read(dev->bright_fd, buf, 3 * sizeof(char)) == -1) {
        syslog(LOG_ERR, "led: read_brightness: Failed to read 'brightness': %s", strerror(errno));
        return MRAA_ERROR_UNSPECIFIED;
    }
    lseek(dev->bright_fd, 0, SEEK_SET);

    return (int) atoi(buf);
}

int
mraa_led_read_max_brightness(mraa_led_context dev)
{
    char buf[3];

    if (dev == NULL) {
        syslog(LOG_ERR, "led: read_max_brightness: context is invalid");
        return MRAA_ERROR_INVALID_HANDLE;
    }

    if (dev->trig_fd != -1) {
        close(dev->trig_fd);
        dev->trig_fd = -1;
    }

    if (dev->bright_fd != -1) {
        close(dev->bright_fd);
        dev->bright_fd = -1;
    }

    if (dev->max_bright_fd == -1) {
        if (mraa_led_get_maxbrightfd(dev) != MRAA_SUCCESS) {
            return MRAA_ERROR_INVALID_RESOURCE;
        }
    } else {
        lseek(dev->max_bright_fd, 0, SEEK_SET);
    }

    if (read(dev->max_bright_fd, buf, 3 * sizeof(char)) == -1) {
        syslog(LOG_ERR, "led: read_max_brightness: Failed to read 'max_brightness': %s", strerror(errno));
        return MRAA_ERROR_UNSPECIFIED;
    }
    lseek(dev->max_bright_fd, 0, SEEK_SET);

    return (int) atoi(buf);
}

mraa_result_t
mraa_led_set_trigger(mraa_led_context dev, const char* trigger)
{
    char buf[MAX_SIZE];
    int length;

    if (dev == NULL) {
        syslog(LOG_ERR, "led: set_trigger: context is invalid");
        return MRAA_ERROR_INVALID_HANDLE;
    }

    if (dev->bright_fd != -1) {
        close(dev->bright_fd);
        dev->bright_fd = -1;
    }

    if (dev->max_bright_fd != -1) {
        close(dev->max_bright_fd);
        dev->max_bright_fd = -1;
    }

    if (trigger == NULL) {
        syslog(LOG_ERR, "led: trigger: invalid trigger specified");
        return MRAA_ERROR_INVALID_RESOURCE;
    }

    if (dev->trig_fd == -1) {
        if (mraa_led_get_trigfd(dev) != MRAA_SUCCESS) {
            return MRAA_ERROR_INVALID_RESOURCE;
        }
    }

    if (lseek(dev->trig_fd, 0, SEEK_SET) == -1) {
        syslog(LOG_ERR, "led: set_trigger: Failed to lseek 'trigger': %s", strerror(errno));
        return MRAA_ERROR_UNSPECIFIED;
    }

    length = snprintf(buf, sizeof(buf), "%s", trigger);
    if (write(dev->trig_fd, buf, length * sizeof(char)) == -1) {
        syslog(LOG_ERR, "led: set_trigger: Failed to write 'trigger': %s", strerror(errno));
        return MRAA_ERROR_UNSPECIFIED;
    }

    return MRAA_SUCCESS;
}

mraa_result_t
mraa_led_clear_trigger(mraa_led_context dev)
{
    char buf[1] = { '0' };

    if (dev == NULL) {
        syslog(LOG_ERR, "led: clear_trigger: context is invalid");
        return MRAA_ERROR_INVALID_HANDLE;
    }

    if (dev->trig_fd != -1) {
        close(dev->trig_fd);
        dev->trig_fd = -1;
    }

    if (dev->max_bright_fd != -1) {
        close(dev->max_bright_fd);
        dev->max_bright_fd = -1;
    }

    if (dev->bright_fd == -1) {
        if (mraa_led_get_brightfd(dev) != MRAA_SUCCESS) {
            return MRAA_ERROR_INVALID_RESOURCE;
        }
    }

    if (lseek(dev->bright_fd, 0, SEEK_SET) == -1) {
        syslog(LOG_ERR, "led: clear_trigger: Failed to lseek 'brightness': %s", strerror(errno));
        return MRAA_ERROR_UNSPECIFIED;
    }

    /* writing 0 to brightness clears trigger */
    if (write(dev->bright_fd, buf, 1) == -1) {
        syslog(LOG_ERR, "led: clear_trigger: Failed to write 'brightness': %s", strerror(errno));
        return MRAA_ERROR_UNSPECIFIED;
    }

    return MRAA_SUCCESS;
}

mraa_result_t
mraa_led_close(mraa_led_context dev)
{
    if (dev == NULL) {
        syslog(LOG_ERR, "led: close: context is invalid");
        return MRAA_ERROR_INVALID_HANDLE;
    }

    if (dev->bright_fd != -1) {
        close(dev->bright_fd);
    }

    if (dev->trig_fd != -1) {
        close(dev->trig_fd);
    }

    if (dev->max_bright_fd != -1) {
        close(dev->max_bright_fd);
    }

    free(dev);

    return MRAA_SUCCESS;
}