linux/arch/x86/boot/video-vesa.c

// SPDX-License-Identifier: GPL-2.0-only
/* -*- linux-c -*- ------------------------------------------------------- *
 *
 *   Copyright (C) 1991, 1992 Linus Torvalds
 *   Copyright 2007 rPath, Inc. - All Rights Reserved
 *   Copyright 2009 Intel Corporation; author H. Peter Anvin
 *
 * ----------------------------------------------------------------------- */

/*
 * VESA text modes
 */

#include "boot.h"
#include "video.h"
#include "vesa.h"
#include "string.h"

/* VESA information */
static struct vesa_general_info vginfo;
static struct vesa_mode_info vminfo;

static __videocard video_vesa;

#ifndef _WAKEUP
static void vesa_store_mode_params_graphics(void);
#else /* _WAKEUP */
static inline void vesa_store_mode_params_graphics(void) { … }
#endif /* _WAKEUP */

static int vesa_probe(void)
{ … }

static int vesa_set_mode(struct mode_info *mode)
{ … }


#ifndef _WAKEUP

/* Switch DAC to 8-bit mode */
static void vesa_dac_set_8bits(void)
{
	struct biosregs ireg, oreg;
	u8 dac_size = 6;

	/* If possible, switch the DAC to 8-bit mode */
	if (vginfo.capabilities & 1) {
		initregs(&ireg);
		ireg.ax = 0x4f08;
		ireg.bh = 0x08;
		intcall(0x10, &ireg, &oreg);
		if (oreg.ax == 0x004f)
			dac_size = oreg.bh;
	}

	/* Set the color sizes to the DAC size, and offsets to 0 */
	boot_params.screen_info.red_size   = dac_size;
	boot_params.screen_info.green_size = dac_size;
	boot_params.screen_info.blue_size  = dac_size;
	boot_params.screen_info.rsvd_size  = dac_size;

	boot_params.screen_info.red_pos    = 0;
	boot_params.screen_info.green_pos  = 0;
	boot_params.screen_info.blue_pos   = 0;
	boot_params.screen_info.rsvd_pos   = 0;
}

/* Save the VESA protected mode info */
static void vesa_store_pm_info(void)
{
	struct biosregs ireg, oreg;

	initregs(&ireg);
	ireg.ax = 0x4f0a;
	intcall(0x10, &ireg, &oreg);

	if (oreg.ax != 0x004f)
		return;

	boot_params.screen_info.vesapm_seg = oreg.es;
	boot_params.screen_info.vesapm_off = oreg.di;
}

/*
 * Save video mode parameters for graphics mode
 */
static void vesa_store_mode_params_graphics(void)
{
	/* Tell the kernel we're in VESA graphics mode */
	boot_params.screen_info.orig_video_isVGA = VIDEO_TYPE_VLFB;

	/* Mode parameters */
	boot_params.screen_info.vesa_attributes = vminfo.mode_attr;
	boot_params.screen_info.lfb_linelength = vminfo.logical_scan;
	boot_params.screen_info.lfb_width = vminfo.h_res;
	boot_params.screen_info.lfb_height = vminfo.v_res;
	boot_params.screen_info.lfb_depth = vminfo.bpp;
	boot_params.screen_info.pages = vminfo.image_planes;
	boot_params.screen_info.lfb_base = vminfo.lfb_ptr;
	memcpy(&boot_params.screen_info.red_size,
	       &vminfo.rmask, 8);

	/* General parameters */
	boot_params.screen_info.lfb_size = vginfo.total_memory;

	if (vminfo.bpp <= 8)
		vesa_dac_set_8bits();

	vesa_store_pm_info();
}

/*
 * Save EDID information for the kernel; this is invoked, separately,
 * after mode-setting.
 */
void vesa_store_edid(void)
{
#ifdef CONFIG_FIRMWARE_EDID
	struct biosregs ireg, oreg;

	/* Apparently used as a nonsense token... */
	memset(&boot_params.edid_info, 0x13, sizeof(boot_params.edid_info));

	if (vginfo.version < 0x0200)
		return;		/* EDID requires VBE 2.0+ */

	initregs(&ireg);
	ireg.ax = 0x4f15;		/* VBE DDC */
	/* ireg.bx = 0x0000; */		/* Report DDC capabilities */
	/* ireg.cx = 0;	*/		/* Controller 0 */
	ireg.es = 0;			/* ES:DI must be 0 by spec */
	intcall(0x10, &ireg, &oreg);

	if (oreg.ax != 0x004f)
		return;		/* No EDID */

	/* BH = time in seconds to transfer EDD information */
	/* BL = DDC level supported */

	ireg.ax = 0x4f15;		/* VBE DDC */
	ireg.bx = 0x0001;		/* Read EDID */
	/* ireg.cx = 0; */		/* Controller 0 */
	/* ireg.dx = 0;	*/		/* EDID block number */
	ireg.es = ds();
	ireg.di =(size_t)&boot_params.edid_info; /* (ES:)Pointer to block */
	intcall(0x10, &ireg, &oreg);
#endif /* CONFIG_FIRMWARE_EDID */
}

#endif /* not _WAKEUP */

static __videocard video_vesa = …;