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video-vga.c

/* -*- linux-c -*- ------------------------------------------------------- *
 *
 *   Copyright (C) 1991, 1992 Linus Torvalds
 *   Copyright 2007 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-vga.c
 *
 * Common all-VGA modes
 */

#include "boot.h"
#include "video.h"

static struct mode_info vga_modes[] = {
      { VIDEO_80x25,  80, 25 },
      { VIDEO_8POINT, 80, 50 },
      { VIDEO_80x43,  80, 43 },
      { VIDEO_80x28,  80, 28 },
      { VIDEO_80x30,  80, 30 },
      { VIDEO_80x34,  80, 34 },
      { VIDEO_80x60,  80, 60 },
};

static struct mode_info ega_modes[] = {
      { VIDEO_80x25,  80, 25 },
      { VIDEO_8POINT, 80, 43 },
};

static struct mode_info cga_modes[] = {
      { VIDEO_80x25,  80, 25 },
};

__videocard video_vga;

/* Set basic 80x25 mode */
static u8 vga_set_basic_mode(void)
{
      u16 ax;
      u8 rows;
      u8 mode;

#ifdef CONFIG_VIDEO_400_HACK
      if (adapter >= ADAPTER_VGA) {
            asm volatile(INT10
                       : : "a" (0x1202), "b" (0x0030)
                       : "ecx", "edx", "esi", "edi");
      }
#endif

      ax = 0x0f00;
      asm volatile(INT10
                 : "+a" (ax)
                 : : "ebx", "ecx", "edx", "esi", "edi");

      mode = (u8)ax;

      set_fs(0);
      rows = rdfs8(0x484);    /* rows minus one */

#ifndef CONFIG_VIDEO_400_HACK
      if ((ax == 0x5003 || ax == 0x5007) &&
          (rows == 0 || rows == 24))
            return mode;
#endif

      if (mode != 3 && mode != 7)
            mode = 3;

      /* Set the mode */
      ax = mode;
      asm volatile(INT10
                 : "+a" (ax)
                 : : "ebx", "ecx", "edx", "esi", "edi");
      do_restore = 1;
      return mode;
}

static void vga_set_8font(void)
{
      /* Set 8x8 font - 80x43 on EGA, 80x50 on VGA */

      /* Set 8x8 font */
      asm volatile(INT10 : : "a" (0x1112), "b" (0));

      /* Use alternate print screen */
      asm volatile(INT10 : : "a" (0x1200), "b" (0x20));

      /* Turn off cursor emulation */
      asm volatile(INT10 : : "a" (0x1201), "b" (0x34));

      /* Cursor is scan lines 6-7 */
      asm volatile(INT10 : : "a" (0x0100), "c" (0x0607));
}

static void vga_set_14font(void)
{
      /* Set 9x14 font - 80x28 on VGA */

      /* Set 9x14 font */
      asm volatile(INT10 : : "a" (0x1111), "b" (0));

      /* Turn off cursor emulation */
      asm volatile(INT10 : : "a" (0x1201), "b" (0x34));

      /* Cursor is scan lines 11-12 */
      asm volatile(INT10 : : "a" (0x0100), "c" (0x0b0c));
}

static void vga_set_80x43(void)
{
      /* Set 80x43 mode on VGA (not EGA) */

      /* Set 350 scans */
      asm volatile(INT10 : : "a" (0x1201), "b" (0x30));

      /* Reset video mode */
      asm volatile(INT10 : : "a" (0x0003));

      vga_set_8font();
}

/* I/O address of the VGA CRTC */
u16 vga_crtc(void)
{
      return (inb(0x3cc) & 1) ? 0x3d4 : 0x3b4;
}

static void vga_set_480_scanlines(int end)
{
      u16 crtc;
      u8  csel;

      crtc = vga_crtc();

      out_idx(0x0c, crtc, 0x11); /* Vertical sync end, unlock CR0-7 */
      out_idx(0x0b, crtc, 0x06); /* Vertical total */
      out_idx(0x3e, crtc, 0x07); /* Vertical overflow */
      out_idx(0xea, crtc, 0x10); /* Vertical sync start */
      out_idx(end, crtc, 0x12); /* Vertical display end */
      out_idx(0xe7, crtc, 0x15); /* Vertical blank start */
      out_idx(0x04, crtc, 0x16); /* Vertical blank end */
      csel = inb(0x3cc);
      csel &= 0x0d;
      csel |= 0xe2;
      outb(csel, 0x3cc);
}

static void vga_set_80x30(void)
{
      vga_set_480_scanlines(0xdf);
}

static void vga_set_80x34(void)
{
      vga_set_14font();
      vga_set_480_scanlines(0xdb);
}

static void vga_set_80x60(void)
{
      vga_set_8font();
      vga_set_480_scanlines(0xdf);
}

static int vga_set_mode(struct mode_info *mode)
{
      /* Set the basic mode */
      vga_set_basic_mode();

      /* Override a possibly broken BIOS */
      force_x = mode->x;
      force_y = mode->y;

      switch (mode->mode) {
      case VIDEO_80x25:
            break;
      case VIDEO_8POINT:
            vga_set_8font();
            break;
      case VIDEO_80x43:
            vga_set_80x43();
            break;
      case VIDEO_80x28:
            vga_set_14font();
            break;
      case VIDEO_80x30:
            vga_set_80x30();
            break;
      case VIDEO_80x34:
            vga_set_80x34();
            break;
      case VIDEO_80x60:
            vga_set_80x60();
            break;
      }

      return 0;
}

/*
 * Note: this probe includes basic information required by all
 * systems.  It should be executed first, by making sure
 * video-vga.c is listed first in the Makefile.
 */
static int vga_probe(void)
{
      static const char *card_name[] = {
            "CGA/MDA/HGC", "EGA", "VGA"
      };
      static struct mode_info *mode_lists[] = {
            cga_modes,
            ega_modes,
            vga_modes,
      };
      static int mode_count[] = {
            sizeof(cga_modes)/sizeof(struct mode_info),
            sizeof(ega_modes)/sizeof(struct mode_info),
            sizeof(vga_modes)/sizeof(struct mode_info),
      };
      u8 vga_flag;

      asm(INT10
          : "=b" (boot_params.screen_info.orig_video_ega_bx)
          : "a" (0x1200), "b" (0x10) /* Check EGA/VGA */
          : "ecx", "edx", "esi", "edi");

      /* If we have MDA/CGA/HGC then BL will be unchanged at 0x10 */
      if ((u8)boot_params.screen_info.orig_video_ega_bx != 0x10) {
            /* EGA/VGA */
            asm(INT10
                : "=a" (vga_flag)
                : "a" (0x1a00)
                : "ebx", "ecx", "edx", "esi", "edi");

            if (vga_flag == 0x1a) {
                  adapter = ADAPTER_VGA;
                  boot_params.screen_info.orig_video_isVGA = 1;
            } else {
                  adapter = ADAPTER_EGA;
            }
      } else {
            adapter = ADAPTER_CGA;
      }

      video_vga.modes = mode_lists[adapter];
      video_vga.card_name = card_name[adapter];
      return mode_count[adapter];
}

__videocard video_vga =
{
      .card_name  = "VGA",
      .probe            = vga_probe,
      .set_mode   = vga_set_mode,
};

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