nativeos/kernel/device/vgafb.c

/**
 * \file
 * \brief VGA Framebuffer
 *
 * The VGA Framebuffer is a block device that exposes the memory region
 * reserved to the framebuffer, so that other code can use VFS operations
 * to get or change the contents of the screen.
 *
 * Applications will usually not use this file directly, but rather delegate
 * changing the contents of the screen to the virtual console device, which
 * also will make additional transformations, such as changing attributes.
 */

#include "vgafb.h"
#include <machine/cpu.h>
#include <sys/device.h>
#include <sys/stdkern.h>
#include <sys/vfs.h>

#define VGA_BASE 0xB8000
#define VGA_COLS 80
#define VGA_ROWS 25
#define VGA_CHARS (VGA_COLS * VGA_ROWS)
#define VGA_SIZE (VGA_CHARS * 2)
#define VGA_LIMIT (VGA_BASE + VGA_SIZE)

#define VGA_IOR_ADDR 0x3D4
#define VGA_IOR_DATA 0x3D5

static int vgafb_init(void);
static int vgafb_open(unsigned int flags);
static int vgafb_close(void);
static unsigned int
vgafb_read(unsigned char *buf, unsigned int off, unsigned int len);
static unsigned int
vgafb_write(unsigned char *buf, unsigned int off, unsigned int len);
static int vgafb_ioctl(int iorq, void *argp);

static driver_t vgafb_driver = {
    .drv_name = "vgafb",
    .drv_flags = DV_FBLCKDEV,
    .drv_init = &vgafb_init,
};

static device_t vgafb_device = {
    .dev_family = &vgafb_driver,
    .dev_open = &vgafb_open,
    .dev_close = &vgafb_close,
    .dev_read_blk = &vgafb_read,
    .dev_write_blk = &vgafb_write,
    .dev_ioctl = &vgafb_ioctl,
};

static int
vgafb_init(void)
{
	unsigned int i;
	unsigned short *vga = (unsigned short *) VGA_BASE;

	if (device_install(&vgafb_device, "fb") < 0) {
		return -1;
	}
	for (i = 0; i < VGA_CHARS; i++)
		vga[i] = 0x700;
	return 0;
}

static int
vgafb_open(unsigned int flags)
{
	return 0;
}

static int
vgafb_close(void)
{
	return 0;
}

static unsigned int
vgafb_read(unsigned char *buf, unsigned int offt, unsigned int len)
{
	unsigned char *start, *end, *ptr;
	unsigned int read_bytes = 0;

	if (offt < VGA_SIZE) {
		start = (unsigned char *) VGA_BASE + offt;
		end = start + len;
		if (end >= (unsigned char *) VGA_LIMIT) {
			end = (unsigned char *) VGA_LIMIT;
		}

		for (ptr = start; ptr < end; ptr++) {
			*buf++ = *ptr;
			read_bytes++;
		}
	}

	return read_bytes;
}

static unsigned int
vgafb_write(unsigned char *buf, unsigned int offt, unsigned int len)
{
	unsigned char *start, *end, *ptr;
	unsigned int write_bytes = 0;

	if (offt < VGA_SIZE) {
		start = (unsigned char *) VGA_BASE + offt;
		end = start + len;
		if (end >= (unsigned char *) VGA_LIMIT) {
			end = (unsigned char *) VGA_LIMIT;
		}

		for (ptr = start; ptr < end; ptr++) {
			*ptr = *buf++;
			write_bytes++;
		}
	}

	return write_bytes;
}

static void
enablecursor(int enabled)
{
	unsigned char in;
	if (enabled) {
		port_out_byte(VGA_IOR_ADDR, 0xA);
		in = port_in_byte(VGA_IOR_DATA) & 0x1F;
		port_out_byte(VGA_IOR_DATA, in | 0xD);
		port_out_byte(VGA_IOR_ADDR, 0xB);
		in = port_in_byte(VGA_IOR_DATA) & 0xC0;
		port_out_byte(VGA_IOR_DATA, in | 0xF);
	} else {
		port_out_byte(VGA_IOR_ADDR, 0xA);
		port_out_byte(VGA_IOR_DATA, 0x20);
	}
}

static void
movecursor(unsigned short abspos)
{
	port_out_byte(VGA_IOR_ADDR, 0xE);
	port_out_byte(VGA_IOR_DATA, (abspos >> 8) & 0xFF);
	port_out_byte(VGA_IOR_ADDR, 0xF);
	port_out_byte(VGA_IOR_DATA, abspos & 0xFF);
}

static int
vgafb_ioctl(int iorq, void *arg)
{
	switch (iorq) {
	case VGAFB_IOCTL_SETCUR:
		enablecursor(((int) arg) != 0);
		return 0;
	case VGAFB_IOCTL_MOVECUR:
		movecursor(*(unsigned short *) arg);
		return 0;
	}

	return -1;
}

DEVICE_DESCRIPTOR(vgafb, vgafb_driver);