/* -*- linux-c -*- ------------------------------------------------------- *
   *
   *   Copyright (C) 1991, 1992 Linus Torvalds
   *   Copyright 2007-2008 rPath, Inc. - All Rights Reserved
   *
   *   This file is part of the Linux kernel, and is made available under
   *   the terms of the GNU General Public License version 2.
   *
   * ----------------------------------------------------------------------- */
  
  /*
   * arch/i386/boot/video-mode.c
   *
   * Set the video mode.  This is separated out into a different
   * file in order to be shared with the ACPI wakeup code.
   */
  
  #include "boot.h"
  #include "video.h"
  #include "vesa.h"
  
  /*
   * Common variables
   */
  int adapter;			/* 0=CGA/MDA/HGC, 1=EGA, 2=VGA+ */
  u16 video_segment;
  int force_x, force_y;	/* Don't query the BIOS for cols/rows */
  
  int do_restore;		/* Screen contents changed during mode flip */
  int graphic_mode;	/* Graphic mode with linear frame buffer */
  
  /* Probe the video drivers and have them generate their mode lists. */
  void probe_cards(int unsafe)
  {
  	struct card_info *card;
  	static u8 probed[2];
  
  	if (probed[unsafe])
  		return;
  
  	probed[unsafe] = 1;
  
  	for (card = video_cards; card < video_cards_end; card++) {
  		if (card->unsafe == unsafe) {
  			if (card->probe)
  				card->nmodes = card->probe();
  			else
  				card->nmodes = 0;
  		}
  	}
  }
  
  /* Test if a mode is defined */
  int mode_defined(u16 mode)
  {
  	struct card_info *card;
  	struct mode_info *mi;
  	int i;
  
  	for (card = video_cards; card < video_cards_end; card++) {
  		mi = card->modes;
  		for (i = 0; i < card->nmodes; i++, mi++) {
  			if (mi->mode == mode)
  				return 1;
  		}
  	}
  
  	return 0;
  }
  
  /* Set mode (without recalc) */
  static int raw_set_mode(u16 mode, u16 *real_mode)
  {
  	int nmode, i;
  	struct card_info *card;
  	struct mode_info *mi;
  
  	/* Drop the recalc bit if set */
  	mode &= ~VIDEO_RECALC;
  
  	/* Scan for mode based on fixed ID, position, or resolution */
  	nmode = 0;
  	for (card = video_cards; card < video_cards_end; card++) {
  		mi = card->modes;
  		for (i = 0; i < card->nmodes; i++, mi++) {
  			int visible = mi->x || mi->y;
  
  			if ((mode == nmode && visible) ||
  			    mode == mi->mode ||
  			    mode == (mi->y << 8)+mi->x) {
  				*real_mode = mi->mode;
  				return card->set_mode(mi);
  			}
  
  			if (visible)
  				nmode++;
  		}
  	}
  
  	/* Nothing found?  Is it an "exceptional" (unprobed) mode? */
  	for (card = video_cards; card < video_cards_end; card++) {
  		if (mode >= card->xmode_first &&
  		    mode < card->xmode_first+card->xmode_n) {
  			struct mode_info mix;
  			*real_mode = mix.mode = mode;
  			mix.x = mix.y = 0;
  			return card->set_mode(&mix);
  		}
  	}
  
  	/* Otherwise, failure... */
  	return -1;
  }
  
  /*
   * Recalculate the vertical video cutoff (hack!)
   */
  static void vga_recalc_vertical(void)
  {
  	unsigned int font_size, rows;
  	u16 crtc;
  	u8 pt, ov;
  
  	set_fs(0);
  	font_size = rdfs8(0x485); /* BIOS: font size (pixels) */
  	rows = force_y ? force_y : rdfs8(0x484)+1; /* Text rows */
  
  	rows *= font_size;	/* Visible scan lines */
  	rows--;			/* ... minus one */
  
  	crtc = vga_crtc();
  
  	pt = in_idx(crtc, 0x11);
  	pt &= ~0x80;		/* Unlock CR0-7 */
  	out_idx(pt, crtc, 0x11);
  
  	out_idx((u8)rows, crtc, 0x12); /* Lower height register */
  
  	ov = in_idx(crtc, 0x07); /* Overflow register */
  	ov &= 0xbd;
  	ov |= (rows >> (8-1)) & 0x02;
  	ov |= (rows >> (9-6)) & 0x40;
  	out_idx(ov, crtc, 0x07);
  }
  
  /* Set mode (with recalc if specified) */
  int set_mode(u16 mode)
  {
  	int rv;
  	u16 real_mode;
  
  	/* Very special mode numbers... */
  	if (mode == VIDEO_CURRENT_MODE)
  		return 0;	/* Nothing to do... */
  	else if (mode == NORMAL_VGA)
  		mode = VIDEO_80x25;
  	else if (mode == EXTENDED_VGA)
  		mode = VIDEO_8POINT;
  
  	rv = raw_set_mode(mode, &real_mode);
  	if (rv)
  		return rv;
  
  	if (mode & VIDEO_RECALC)
  		vga_recalc_vertical();
  
  	/* Save the canonical mode number for the kernel, not
  	   an alias, size specification or menu position */
  #ifndef _WAKEUP
  	boot_params.hdr.vid_mode = real_mode;
  #endif
  	return 0;
  }