k400_plus_conf.c

/*
 * Logitech K400 Plus https://github.com/lenisko/k400_plus by @lenisko
 *
 * based on Mario Scholz <mario@expires-2013.mail.trial-n-error.net> k810_conf.c
 *    see also http://trial-n-error.de/posts/2012/12/31/logitech-k810-keyboard-configurator
 *
 * which was based on pairing_tool.c from Benjamin Tissoires <benjamin.tissoires@gmail.com>
 *    see also https://lkml.org/lkml/2011/9/22/367
 *
 * 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 <linux/input.h>
#include <linux/hidraw.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>

#define HID_VENDOR_ID_LOGITECH          (__u32)0x046d
#define HID_DEVICE_ID_K400_PLUS         (__s16)0x404d

const char k400_plus_seq_fkeys_on[] =   { 0x10, 0x01, 0x09, 0x19, 0x00, 0x00, 0x00 };
const char k400_plus_seq_fkeys_off[] =  { 0x10, 0x01, 0x09, 0x18, 0x01, 0x00, 0x00 };

const char opt_on[]  = "on";
const char opt_off[] = "off";

void send(const int fd, const char* buf, const int len) {
    int res;

    /* Send sequence to the Device */
    res = write(fd, buf, len);

    if (res < 0) {
        printf("Error: %d\n", errno);
        perror("write");
    }
    else {
        errno = ENOMEM;
        printf("write: %d were written instead of %d.\n", res, len);
    }
}

int main(int argc, char** argv) {
    int fd;
    int res;
    struct hidraw_devinfo info;
    const char* seq;
    char* dev = NULL;
    int flag_fkeys = 1;
    int c;

    if (argc < 5) {
        printf("Logitech K400 Plus Keyboard Configurator\n\n");
        printf("Usage: %s -d /dev/hidraw{0,1,...} -f {on|off}:\n\n", argv[0]);
        printf("-d /dev/hidrawX\n"
               "   Path to hidraw device. Determine by e.g.:\n"
               "     ls /sys/class/hidraw/hidraw*/device/uevent\n"
               "   and/or\n"
               "     cat /sys/class/hidraw/hidraw*/device/uevent\n"
               "-f <on|off>\n"
               "   To enable direct access to F-keys.\n\n");
    }

    while ((c = getopt(argc, argv, "d:f:")) != -1) {
        switch (c) {
        case 'd':
            dev = optarg;
            break;
        case 'f':
            if (strcmp(opt_on, optarg) == 0) {
                flag_fkeys = 1;
            }
            else if (strcmp(opt_off, optarg) == 0) {
                flag_fkeys = 0;
            }
            else {
                fprintf(stderr, "Option -%c requires argument '%s' or '%s'.\n", optopt, opt_on, opt_off);
                return 1;
            }
            break;
        case '?':
            if (optopt == 'f') {
                fprintf(stderr, "Option -%c requires an argument.\n", optopt);
            }
            else if (isprint(optopt)) {
                fprintf(stderr, "Unknown option `-%c'.\n", optopt);
            }
            else {
                fprintf(stderr, "Unknown option character `\\x%x'.\n", optopt);
            }
            return 1;
        default:
            abort();
        }
    }

    /* Open the Device with non-blocking reads. */
    fd = open(dev, O_RDWR | O_NONBLOCK);
    if (fd < 0) {
        perror("Unable to open device");
        return 1;
    }

    /* Get Raw Info */
    res = ioctl(fd, HIDIOCGRAWINFO, &info);
    if (res < 0) {
        perror("error while getting info from device");
    }
    else {
        if (info.vendor != HID_VENDOR_ID_LOGITECH || info.product != HID_DEVICE_ID_K400_PLUS) {
            errno = EPERM;
            perror("The given device is not a supported Logitech keyboard");

            return 1;
        }
    }

    if (flag_fkeys) {
        send(fd, k400_plus_seq_fkeys_on, sizeof(k400_plus_seq_fkeys_on));
    }
    else {
        send(fd, k400_plus_seq_fkeys_off, sizeof(k400_plus_seq_fkeys_off));
    }

    close(fd);
    return 0;
}