RockOS/kernel/drivers/vga/vga.c

#include "vfs.h"
#include <stddef.h>
#include <stdint.h>

#include <lib/print.h>

#include <drivers/vga/vga.h>
#include <drivers/serial/serial.h>

#include <common.h>
#include <memory/mm.h>

#include <sys/video.h>

static uint32_t framebuffer_address;
static uint32_t framebuffer_width;
static uint32_t framebuffer_height;
static uint32_t framebuffer_total_pixels;
static uint32_t framebuffer_pitch;
static uint32_t framebuffer_bpp;

vga_color_t VGA_COLOR_BLACK = {0, 0, 0, 255};
vga_color_t VGA_COLOR_RED	= {0, 0, 255, 255};
vga_color_t VGA_COLOR_GREEN	= {0, 255, 0, 255};
vga_color_t VGA_COLOR_BLUE	= {255, 0, 0, 255};

uint32_t vga_mmap(vfs_node_t* node, uint32_t address) {
	uint32_t fb_size_bytes = framebuffer_height * framebuffer_pitch;
	uint32_t num_pages = (fb_size_bytes + 4095) / 4096; 
	for (uint32_t i = 0; i < num_pages; i++) {
		uint32_t phys_addr = framebuffer_address + (i * 4096);
		uint32_t virt_addr = address + (i * 4096);
		map_page(virt_addr, phys_addr, PAGE_PRESENT | PAGE_WRITABLE | PAGE_USER | PAGE_MMIO);
	}
	return address;
}

uint32_t vga_ioctl(vfs_node_t* node, uint32_t request, void* arg) {
	if (request == FBIOGET_INFO) {
		fb_info_t* info = (fb_info_t*)arg;
		info->width = framebuffer_width;
		info->height = framebuffer_height;
		info->pitch = framebuffer_pitch;
		info->fb_size = framebuffer_total_pixels;
		info->bpp = framebuffer_bpp;
		return 1;
	}
	return 0;
}

void vga_init(
	vfs_node_t* dev,
	uint32_t fb_paddr,
	uint32_t fb_width,
	uint32_t fb_height,
	uint32_t fb_pitch,
	uint8_t fb_bpp
) {
	framebuffer_address = fb_paddr;
	framebuffer_width = fb_width;
	framebuffer_height = fb_height;
	framebuffer_total_pixels = framebuffer_width * framebuffer_height;
	framebuffer_pitch = fb_pitch;
	framebuffer_bpp = fb_bpp;

	kprintf("mapping vga pages\n");

	uint32_t fb_size_bytes = fb_height * fb_pitch;
	uint32_t num_pages = (fb_size_bytes + 4095) / 4096; 
	for (uint32_t i = 0; i < num_pages; i++) {
		uint32_t phys_addr = fb_paddr + (i * 4096);
		uint32_t virt_addr = VGA_FRAMEBUFFER + (i * 4096);
		map_page(virt_addr, phys_addr, PAGE_PRESENT | PAGE_WRITABLE | PAGE_MMIO);
	}

	vga_clear_scrn(0x00000000);
	
	dev->flags = VFS_CHARDEVICE;
	dev->mmap = vga_mmap;
	dev->ioctl = vga_ioctl;
}

uint32_t vga_get_framebuffer() {
	return VGA_FRAMEBUFFER;
}

uint32_t vga_get_width() {
	return framebuffer_width;
}

uint32_t vga_get_height() {
	return framebuffer_height;
}

uint32_t vga_get_pitch() {
	return framebuffer_pitch;
}

uint8_t vga_get_bpp() {
	return framebuffer_bpp;
}

void vga_clear_scrn(uint32_t color) {
    uint8_t* fb_bytes = (uint8_t*)VGA_FRAMEBUFFER;
    uint8_t bytes_per_pixel = framebuffer_bpp / 8;

    for (uint32_t y = 0; y < framebuffer_height; y++) {
        uint8_t* row = fb_bytes + (y * framebuffer_pitch);

        for (uint32_t x = 0; x < framebuffer_width; x++) {
            uint8_t* pixel = row + (x * bytes_per_pixel);

			switch(framebuffer_bpp) {
				case 32: {
					*(uint32_t*)pixel = color;
					break;
				}
			}
        }
    }
}