linux下c语言控制lcd灯

#include <fcntl.h>
#include <linux/fb.h>
#include <sys/mman.h>
#include <unistd.h>

int main() {
    int fbfd = open("/dev/fb0", O_RDWR);
    if (fbfd == -1) {
        perror("Error: cannot open framebuffer device");
        return 1;
    }

    struct fb_var_screeninfo vinfo;
    if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo)) {
        perror("Error reading variable information");
        close(fbfd);
        return 1;
    }

    long screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
    char *fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fbfd, 0);
    if ((int)fbp == -1) {
        perror("Error: failed to map framebuffer device to memory");
        close(fbfd);
        return 1;
    }

    // Clear the screen
    memset(fbp, 0, screensize);

    // Draw a simple pattern
    for (int y = 100; y < 200; y++) {
        for (int x = 100; x < 200; x++) {
            long location = (x+vinfo.xoffset) * (vinfo.bits_per_pixel/8) +
                            (y+vinfo.yoffset) * vinfo.xres * (vinfo.bits_per_pixel/8);
            *(fbp + location) = 255;     // Some blue
            *(fbp + location + 1) = 127; // Some green
            *(fbp + location + 2) = 0;   // Some red
        }
    }

    munmap(fbp, screensize);
    close(fbfd);
    return 0;
}