lvgl_cpp/lv_drivers/display/fbdev.c

/**
 * @file fbdev.c
 *
 */

/*********************
 *      INCLUDES
 *********************/
#include "fbdev.h"
#if USE_FBDEV || USE_BSD_FBDEV

#include <stdlib.h>
#include <unistd.h>
#include <stddef.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/ioctl.h>

#if USE_BSD_FBDEV
#include <sys/fcntl.h>
#include <sys/time.h>
#include <sys/consio.h>
#include <sys/fbio.h>
#else  /* USE_BSD_FBDEV */
#include <linux/fb.h>
#endif /* USE_BSD_FBDEV */

/*********************
 *      DEFINES
 *********************/
#ifndef FBDEV_PATH
#define FBDEV_PATH  "/dev/fb0"
#endif

/**********************
 *      TYPEDEFS
 **********************/

/**********************
 *      STRUCTURES
 **********************/

struct bsd_fb_var_info{
    uint32_t xoffset;
    uint32_t yoffset;
    uint32_t xres;
    uint32_t yres;
    int bits_per_pixel;
 };

struct bsd_fb_fix_info{
    long int line_length;
    long int smem_len;
};

/**********************
 *  STATIC PROTOTYPES
 **********************/

/**********************
 *  STATIC VARIABLES
 **********************/
#if USE_BSD_FBDEV
static struct bsd_fb_var_info vinfo;
static struct bsd_fb_fix_info finfo;
#else
static struct fb_var_screeninfo vinfo;
static struct fb_fix_screeninfo finfo;
#endif /* USE_BSD_FBDEV */
static char *fbp = 0;
static long int screensize = 0;
static int fbfd = 0;

/**********************
 *      MACROS
 **********************/

#if USE_BSD_FBDEV
#define FBIOBLANK FBIO_BLANK
#endif /* USE_BSD_FBDEV */

/**********************
 *   GLOBAL FUNCTIONS
 **********************/

void fbdev_init(void)
{
    // Open the file for reading and writing
    fbfd = open(FBDEV_PATH, O_RDWR);
    if(fbfd == -1) {
        perror("Error: cannot open framebuffer device");
        return;
    }
    LV_LOG_INFO("The framebuffer device was opened successfully");

    // Make sure that the display is on.
    if (ioctl(fbfd, FBIOBLANK, FB_BLANK_UNBLANK) != 0) {
        perror("ioctl(FBIOBLANK)");
        return;
    }

#if USE_BSD_FBDEV
    struct fbtype fb;
    unsigned line_length;

    //Get fb type
    if (ioctl(fbfd, FBIOGTYPE, &fb) != 0) {
        perror("ioctl(FBIOGTYPE)");
        return;
    }

    //Get screen width
    if (ioctl(fbfd, FBIO_GETLINEWIDTH, &line_length) != 0) {
        perror("ioctl(FBIO_GETLINEWIDTH)");
        return;
    }

    vinfo.xres = (unsigned) fb.fb_width;
    vinfo.yres = (unsigned) fb.fb_height;
    vinfo.bits_per_pixel = fb.fb_depth;
    vinfo.xoffset = 0;
    vinfo.yoffset = 0;
    finfo.line_length = line_length;
    finfo.smem_len = finfo.line_length * vinfo.yres;
#else /* USE_BSD_FBDEV */

    // Get fixed screen information
    if(ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo) == -1) {
        perror("Error reading fixed information");
        return;
    }

    // Get variable screen information
    if(ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo) == -1) {
        perror("Error reading variable information");
        return;
    }
#endif /* USE_BSD_FBDEV */

    LV_LOG_INFO("%dx%d, %dbpp", vinfo.xres, vinfo.yres, vinfo.bits_per_pixel);

    // Figure out the size of the screen in bytes
    screensize =  finfo.smem_len; //finfo.line_length * vinfo.yres;    

    // Map the device to memory
    fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fbfd, 0);
    if((intptr_t)fbp == -1) {
        perror("Error: failed to map framebuffer device to memory");
        return;
    }

    // Don't initialise the memory to retain what's currently displayed / avoid clearing the screen.
    // This is important for applications that only draw to a subsection of the full framebuffer.

    LV_LOG_INFO("The framebuffer device was mapped to memory successfully");

}

void fbdev_exit(void)
{
    close(fbfd);
}

/**
 * Flush a buffer to the marked area
 * @param drv pointer to driver where this function belongs
 * @param area an area where to copy `color_p`
 * @param color_p an array of pixels to copy to the `area` part of the screen
 */
void fbdev_flush(lv_disp_drv_t * drv, const lv_area_t * area, lv_color_t * color_p)
{
    if(fbp == NULL ||
            area->x2 < 0 ||
            area->y2 < 0 ||
            area->x1 > (int32_t)vinfo.xres - 1 ||
            area->y1 > (int32_t)vinfo.yres - 1) {
        lv_disp_flush_ready(drv);
        return;
    }

    /*Truncate the area to the screen*/
    int32_t act_x1 = area->x1 < 0 ? 0 : area->x1;
    int32_t act_y1 = area->y1 < 0 ? 0 : area->y1;
    int32_t act_x2 = area->x2 > (int32_t)vinfo.xres - 1 ? (int32_t)vinfo.xres - 1 : area->x2;
    int32_t act_y2 = area->y2 > (int32_t)vinfo.yres - 1 ? (int32_t)vinfo.yres - 1 : area->y2;


    lv_coord_t w = (act_x2 - act_x1 + 1);
    long int location = 0;
    long int byte_location = 0;
    unsigned char bit_location = 0;

    /*32 or 24 bit per pixel*/
    if(vinfo.bits_per_pixel == 32 || vinfo.bits_per_pixel == 24) {
        uint32_t * fbp32 = (uint32_t *)fbp;
        int32_t y;
        for(y = act_y1; y <= act_y2; y++) {
            location = (act_x1 + vinfo.xoffset) + (y + vinfo.yoffset) * finfo.line_length / 4;
            memcpy(&fbp32[location], (uint32_t *)color_p, (act_x2 - act_x1 + 1) * 4);
            color_p += w;
        }
    }
    /*16 bit per pixel*/
    else if(vinfo.bits_per_pixel == 16) {
        uint16_t * fbp16 = (uint16_t *)fbp;
        int32_t y;
        for(y = act_y1; y <= act_y2; y++) {
            location = (act_x1 + vinfo.xoffset) + (y + vinfo.yoffset) * finfo.line_length / 2;
            memcpy(&fbp16[location], (uint32_t *)color_p, (act_x2 - act_x1 + 1) * 2);
            color_p += w;
        }
    }
    /*8 bit per pixel*/
    else if(vinfo.bits_per_pixel == 8) {
        uint8_t * fbp8 = (uint8_t *)fbp;
        int32_t y;
        for(y = act_y1; y <= act_y2; y++) {
            location = (act_x1 + vinfo.xoffset) + (y + vinfo.yoffset) * finfo.line_length;
            memcpy(&fbp8[location], (uint32_t *)color_p, (act_x2 - act_x1 + 1));
            color_p += w;
        }
    }
    /*1 bit per pixel*/
    else if(vinfo.bits_per_pixel == 1) {
        uint8_t * fbp8 = (uint8_t *)fbp;
        int32_t x;
        int32_t y;
        for(y = act_y1; y <= act_y2; y++) {
            for(x = act_x1; x <= act_x2; x++) {
                location = (x + vinfo.xoffset) + (y + vinfo.yoffset) * vinfo.xres;
                byte_location = location / 8; /* find the byte we need to change */
                bit_location = location % 8; /* inside the byte found, find the bit we need to change */
                fbp8[byte_location] &= ~(((uint8_t)(1)) << bit_location);
                fbp8[byte_location] |= ((uint8_t)(color_p->full)) << bit_location;
                color_p++;
            }

            color_p += area->x2 - act_x2;
        }
    } else {
        /*Not supported bit per pixel*/
    }

    //May be some direct update command is required
    //ret = ioctl(state->fd, FBIO_UPDATE, (unsigned long)((uintptr_t)rect));

    lv_disp_flush_ready(drv);
}

void fbdev_get_sizes(uint32_t *width, uint32_t *height) {
    if (width)
        *width = vinfo.xres;

    if (height)
        *height = vinfo.yres;
}

void fbdev_set_offset(uint32_t xoffset, uint32_t yoffset) {
    vinfo.xoffset = xoffset;
    vinfo.yoffset = yoffset;
}

/**********************
 *   STATIC FUNCTIONS
 **********************/

#endif