/*
 * linux/drivers/video/vga16.c -- VGA 16-color framebuffer driver
 * 
 * Copyright 1999 Ben Pfaff <pfaffben@debian.org> and Petr Vandrovec <VANDROVE@vc.cvut.cz>
 * Based on VGA info at http://www.goodnet.com/~tinara/FreeVGA/home.htm
 * Based on VESA framebuffer (c) 1998 Gerd Knorr <kraxel@goldbach.in-berlin.de>
 *
 * This file is subject to the terms and conditions of the GNU General
 * Public License.  See the file COPYING in the main directory of this
 * archive for more details.  
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/fb.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/screen_info.h>

#include <asm/io.h>
#include <video/vga.h>

#define VGA_FB_PHYS 0xA0000
#define VGA_FB_PHYS_LEN 65536

#define MODE_SKIP4      1
#define MODE_8BPP       2
#define MODE_CFB        4
#define MODE_TEXT       8

/* --------------------------------------------------------------------- */

/*
 * card parameters
 */

struct vga16fb_par {
        /* structure holding original VGA register settings when the
           screen is blanked */
        struct {
                unsigned char   SeqCtrlIndex;     /* Sequencer Index reg.   */
                unsigned char   CrtCtrlIndex;     /* CRT-Contr. Index reg.  */
                unsigned char   CrtMiscIO;        /* Miscellaneous register */
                unsigned char   HorizontalTotal;  /* CRT-Controller:00h */
                unsigned char   HorizDisplayEnd;  /* CRT-Controller:01h */
                unsigned char   StartHorizRetrace;/* CRT-Controller:04h */
                unsigned char   EndHorizRetrace;  /* CRT-Controller:05h */
                unsigned char   Overflow;         /* CRT-Controller:07h */
                unsigned char   StartVertRetrace; /* CRT-Controller:10h */
                unsigned char   EndVertRetrace;   /* CRT-Controller:11h */
                unsigned char   ModeControl;      /* CRT-Controller:17h */
                unsigned char   ClockingMode;     /* Seq-Controller:01h */
        } vga_state;
        struct vgastate state;
        unsigned int ref_count;
        int palette_blanked, vesa_blanked, mode, isVGA;
        u8 misc, pel_msk, vss, clkdiv;
        u8 crtc[VGA_CRT_C];
};

/* --------------------------------------------------------------------- */

static struct fb_var_screeninfo vga16fb_defined = {
        .xres           = 640,
        .yres           = 480,
        .xres_virtual   = 640,
        .yres_virtual   = 480,
        .bits_per_pixel = 4,    
        .activate       = FB_ACTIVATE_TEST,
        .height         = -1,
        .width          = -1,
        .pixclock       = 39721,
        .left_margin    = 48,
        .right_margin   = 16,
        .upper_margin   = 33,
        .lower_margin   = 10,
        .hsync_len      = 96,
        .vsync_len      = 2,
        .vmode          = FB_VMODE_NONINTERLACED,
};

/* name should not depend on EGA/VGA */
static const struct fb_fix_screeninfo vga16fb_fix = {
        .id             = "VGA16 VGA",
        .smem_start     = VGA_FB_PHYS,
        .smem_len       = VGA_FB_PHYS_LEN,
        .type           = FB_TYPE_VGA_PLANES,
        .type_aux       = FB_AUX_VGA_PLANES_VGA4,
        .visual         = FB_VISUAL_PSEUDOCOLOR,
        .xpanstep       = 8,
        .ypanstep       = 1,
        .line_length    = 640 / 8,
        .accel          = FB_ACCEL_NONE
};

/* The VGA's weird architecture often requires that we read a byte and
   write a byte to the same location.  It doesn't matter *what* byte
   we write, however.  This is because all the action goes on behind
   the scenes in the VGA's 32-bit latch register, and reading and writing
   video memory just invokes latch behavior.

   To avoid race conditions (is this necessary?), reading and writing
   the memory byte should be done with a single instruction.  One
   suitable instruction is the x86 bitwise OR.  The following
   read-modify-write routine should optimize to one such bitwise
   OR. */
static inline void rmw(volatile char __iomem *p)
{
        readb(p);
        writeb(1, p);
}

/* Set the Graphics Mode Register, and return its previous value.
   Bits 0-1 are write mode, bit 3 is read mode. */
static inline int setmode(int mode)
{
        int oldmode;
        
        oldmode = vga_io_rgfx(VGA_GFX_MODE);
        vga_io_w(VGA_GFX_D, mode);
        return oldmode;
}

/* Select the Bit Mask Register and return its value. */
static inline int selectmask(void)
{
        return vga_io_rgfx(VGA_GFX_BIT_MASK);
}

/* Set the value of the Bit Mask Register.  It must already have been
   selected with selectmask(). */
static inline void setmask(int mask)
{
        vga_io_w(VGA_GFX_D, mask);
}

/* Set the Data Rotate Register and return its old value. 
   Bits 0-2 are rotate count, bits 3-4 are logical operation
   (0=NOP, 1=AND, 2=OR, 3=XOR). */
static inline int setop(int op)
{
        int oldop;
        
        oldop = vga_io_rgfx(VGA_GFX_DATA_ROTATE);
        vga_io_w(VGA_GFX_D, op);
        return oldop;
}

/* Set the Enable Set/Reset Register and return its old value.  
   The code here always uses value 0xf for this register. */
static inline int setsr(int sr)
{
        int oldsr;

        oldsr = vga_io_rgfx(VGA_GFX_SR_ENABLE);
        vga_io_w(VGA_GFX_D, sr);
        return oldsr;
}

/* Set the Set/Reset Register and return its old value. */
static inline int setcolor(int color)
{
        int oldcolor;

        oldcolor = vga_io_rgfx(VGA_GFX_SR_VALUE);
        vga_io_w(VGA_GFX_D, color);
        return oldcolor;
}

/* Return the value in the Graphics Address Register. */
static inline int getindex(void)
{
        return vga_io_r(VGA_GFX_I);
}

/* Set the value in the Graphics Address Register. */
static inline void setindex(int index)
{
        vga_io_w(VGA_GFX_I, index);
}

/* Check if the video mode is supported by the driver */
static inline int check_mode_supported(void)
{
        /* non-x86 architectures treat orig_video_isVGA as a boolean flag */
#if defined(CONFIG_X86)
        /* only EGA and VGA in 16 color graphic mode are supported */
        if (screen_info.orig_video_isVGA != VIDEO_TYPE_EGAC &&
            screen_info.orig_video_isVGA != VIDEO_TYPE_VGAC)
                return -ENODEV;

        if (screen_info.orig_video_mode != 0x0D &&      /* 320x200/4 (EGA) */
            screen_info.orig_video_mode != 0x0E &&      /* 640x200/4 (EGA) */
            screen_info.orig_video_mode != 0x10 &&      /* 640x350/4 (EGA) */
            screen_info.orig_video_mode != 0x12)        /* 640x480/4 (VGA) */
                return -ENODEV;
#endif
        return 0;
}

static void vga16fb_pan_var(struct fb_info *info, 
                            struct fb_var_screeninfo *var)
{
        struct vga16fb_par *par = info->par;
        u32 xoffset, pos;

        xoffset = var->xoffset;
        if (info->var.bits_per_pixel == 8) {
                pos = (info->var.xres_virtual * var->yoffset + xoffset) >> 2;
        } else if (par->mode & MODE_TEXT) {
                int fh = 16; // FIXME !!! font height. Fugde for now.
                pos = (info->var.xres_virtual * (var->yoffset / fh) + xoffset) >> 3;
        } else {
                if (info->var.nonstd)
                        xoffset--;
                pos = (info->var.xres_virtual * var->yoffset + xoffset) >> 3;
        }
        vga_io_wcrt(VGA_CRTC_START_HI, pos >> 8);
        vga_io_wcrt(VGA_CRTC_START_LO, pos & 0xFF);
        /* if we support CFB4, then we must! support xoffset with pixel
         * granularity if someone supports xoffset in bit resolution */
        vga_io_r(VGA_IS1_RC);           /* reset flip-flop */
        vga_io_w(VGA_ATT_IW, VGA_ATC_PEL);
        if (info->var.bits_per_pixel == 8)
                vga_io_w(VGA_ATT_IW, (xoffset & 3) << 1);
        else
                vga_io_w(VGA_ATT_IW, xoffset & 7);
        vga_io_r(VGA_IS1_RC);
        vga_io_w(VGA_ATT_IW, 0x20);
}

static void vga16fb_update_fix(struct fb_info *info)
{
        if (info->var.bits_per_pixel == 4) {
                if (info->var.nonstd) {
                        info->fix.type = FB_TYPE_PACKED_PIXELS;
                        info->fix.line_length = info->var.xres_virtual / 2;
                } else {
                        info->fix.type = FB_TYPE_VGA_PLANES;
                        info->fix.type_aux = FB_AUX_VGA_PLANES_VGA4;
                        info->fix.line_length = info->var.xres_virtual / 8;
                }
        } else if (info->var.bits_per_pixel == 0) {
                info->fix.type = FB_TYPE_TEXT;
                info->fix.type_aux = FB_AUX_TEXT_CGA;
                info->fix.line_length = info->var.xres_virtual / 4;
        } else {        /* 8bpp */
                if (info->var.nonstd) {
                        info->fix.type = FB_TYPE_VGA_PLANES;
                        info->fix.type_aux = FB_AUX_VGA_PLANES_CFB8;
                        info->fix.line_length = info->var.xres_virtual / 4;
                } else {
                        info->fix.type = FB_TYPE_PACKED_PIXELS;
                        info->fix.line_length = info->var.xres_virtual;
                }
        }
}

static void vga16fb_clock_chip(struct vga16fb_par *par,
                               unsigned int *pixclock,
                               const struct fb_info *info,
                               int mul, int div)
{
        static const struct {
                u32 pixclock;
                u8  misc;
                u8  seq_clock_mode;
        } *ptr, *best, vgaclocks[] = {
                { 79442 /* 12.587 */, 0x00, 0x08},
                { 70616 /* 14.161 */, 0x04, 0x08},
                { 39721 /* 25.175 */, 0x00, 0x00},
                { 35308 /* 28.322 */, 0x04, 0x00},
                {     0 /* bad */,    0x00, 0x00}};
        int err;

        *pixclock = (*pixclock * mul) / div;
        best = vgaclocks;
        err = *pixclock - best->pixclock;
        if (err < 0) err = -err;
        for (ptr = vgaclocks + 1; ptr->pixclock; ptr++) {
                int tmp;

                tmp = *pixclock - ptr->pixclock;
                if (tmp < 0) tmp = -tmp;
                if (tmp < err) {
                        err = tmp;
                        best = ptr;
                }
        }
        par->misc |= best->misc;
        par->clkdiv = best->seq_clock_mode;
        *pixclock = (best->pixclock * div) / mul;
}
                               
#define FAIL(X) return -EINVAL

static int vga16fb_open(struct fb_info *info, int user)
{
        struct vga16fb_par *par = info->par;

        if (!par->ref_count) {
                memset(&par->state, 0, sizeof(struct vgastate));
                par->state.flags = VGA_SAVE_FONTS | VGA_SAVE_MODE |
                        VGA_SAVE_CMAP;
                save_vga(&par->state);
        }
        par->ref_count++;

        return 0;
}

static int vga16fb_release(struct fb_info *info, int user)
{
        struct vga16fb_par *par = info->par;

        if (!par->ref_count)
                return -EINVAL;

        if (par->ref_count == 1)
                restore_vga(&par->state);
        par->ref_count--;

        return 0;
}

static int vga16fb_check_var(struct fb_var_screeninfo *var,
                             struct fb_info *info)
{
        struct vga16fb_par *par = info->par;
        u32 xres, right, hslen, left, xtotal;
        u32 yres, lower, vslen, upper, ytotal;
        u32 vxres, xoffset, vyres, yoffset;
        u32 pos;
        u8 r7, rMode;
        int shift;
        int mode;
        u32 maxmem;

        par->pel_msk = 0xFF;

        if (var->bits_per_pixel == 4) {
                if (var->nonstd) {
                        if (!par->isVGA)
                                return -EINVAL;
                        shift = 3;
                        mode = MODE_SKIP4 | MODE_CFB;
                        maxmem = 16384;
                        par->pel_msk = 0x0F;
                } else {
                        shift = 3;
                        mode = 0;
                        maxmem = 65536;
                }
        } else if (var->bits_per_pixel == 8) {
                if (!par->isVGA)
                        return -EINVAL; /* no support on EGA */
                shift = 2;
                if (var->nonstd) {
                        mode = MODE_8BPP | MODE_CFB;
                        maxmem = 65536;
                } else {
                        mode = MODE_SKIP4 | MODE_8BPP | MODE_CFB;
                        maxmem = 16384;
                }
        } else
                return -EINVAL;

        xres = (var->xres + 7) & ~7;
        vxres = (var->xres_virtual + 0xF) & ~0xF;
        xoffset = (var->xoffset + 7) & ~7;
        left = (var->left_margin + 7) & ~7;
        right = (var->right_margin + 7) & ~7;
        hslen = (var->hsync_len + 7) & ~7;

        if (vxres < xres)
                vxres = xres;
        if (xres + xoffset > vxres)
                xoffset = vxres - xres;

        var->xres = xres;
        var->right_margin = right;
        var->hsync_len = hslen;
        var->left_margin = left;
        var->xres_virtual = vxres;
        var->xoffset = xoffset;

        xres >>= shift;
        right >>= shift;
        hslen >>= shift;
        left >>= shift;
        vxres >>= shift;
        xtotal = xres + right + hslen + left;
        if (xtotal >= 256)
                FAIL("xtotal too big");
        if (hslen > 32)
                FAIL("hslen too big");
        if (right + hslen + left > 64)
                FAIL("hblank too big");
        par->crtc[VGA_CRTC_H_TOTAL] = xtotal - 5;
        par->crtc[VGA_CRTC_H_BLANK_START] = xres - 1;
        par->crtc[VGA_CRTC_H_DISP] = xres - 1;
        pos = xres + right;
        par->crtc[VGA_CRTC_H_SYNC_START] = pos;
        pos += hslen;
        par->crtc[VGA_CRTC_H_SYNC_END] = pos & 0x1F;
        pos += left - 2; /* blank_end + 2 <= total + 5 */
        par->crtc[VGA_CRTC_H_BLANK_END] = (pos & 0x1F) | 0x80;
        if (pos & 0x20)
                par->crtc[VGA_CRTC_H_SYNC_END] |= 0x80;

        yres = var->yres;
        lower = var->lower_margin;
        vslen = var->vsync_len;
        upper = var->upper_margin;
        vyres = var->yres_virtual;
        yoffset = var->yoffset;

        if (yres > vyres)
                vyres = yres;
        if (vxres * vyres > maxmem) {
                vyres = maxmem / vxres;
                if (vyres < yres)
                        return -ENOMEM;
        }
        if (yoffset + yres > vyres)
                yoffset = vyres - yres;
        var->yres = yres;
        var->lower_margin = lower;
        var->vsync_len = vslen;
        var->upper_margin = upper;
        var->yres_virtual = vyres;
        var->yoffset = yoffset;

        if (var->vmode & FB_VMODE_DOUBLE) {
                yres <<= 1;
                lower <<= 1;
                vslen <<= 1;
                upper <<= 1;
        }
        ytotal = yres + lower + vslen + upper;
        if (ytotal > 1024) {
                ytotal >>= 1;
                yres >>= 1;
                lower >>= 1;
                vslen >>= 1;
                upper >>= 1;
                rMode = 0x04;
        } else
                rMode = 0x00;
        if (ytotal > 1024)
                FAIL("ytotal too big");
        if (vslen > 16)
                FAIL("vslen too big");
        par->crtc[VGA_CRTC_V_TOTAL] = ytotal - 2;
        r7 = 0x10;      /* disable linecompare */
        if (ytotal & 0x100) r7 |= 0x01;
        if (ytotal & 0x200) r7 |= 0x20;
        par->crtc[VGA_CRTC_PRESET_ROW] = 0;
        par->crtc[VGA_CRTC_MAX_SCAN] = 0x40;    /* 1 scanline, no linecmp */
        if (var->vmode & FB_VMODE_DOUBLE)
                par->crtc[VGA_CRTC_MAX_SCAN] |= 0x80;
        par->crtc[VGA_CRTC_CURSOR_START] = 0x20;
        par->crtc[VGA_CRTC_CURSOR_END]   = 0x00;
        if ((mode & (MODE_CFB | MODE_8BPP)) == MODE_CFB)
                xoffset--;
        pos = yoffset * vxres + (xoffset >> shift);
        par->crtc[VGA_CRTC_START_HI]     = pos >> 8;
        par->crtc[VGA_CRTC_START_LO]     = pos & 0xFF;
        par->crtc[VGA_CRTC_CURSOR_HI]    = 0x00;
        par->crtc[VGA_CRTC_CURSOR_LO]    = 0x00;
        pos = yres - 1;
        par->crtc[VGA_CRTC_V_DISP_END] = pos & 0xFF;
        par->crtc[VGA_CRTC_V_BLANK_START] = pos & 0xFF;
        if (pos & 0x100)
                r7 |= 0x0A;     /* 0x02 -> DISP_END, 0x08 -> BLANK_START */
        if (pos & 0x200) {
                r7 |= 0x40;     /* 0x40 -> DISP_END */
                par->crtc[VGA_CRTC_MAX_SCAN] |= 0x20; /* BLANK_START */
        }
        pos += lower;
        par->crtc[VGA_CRTC_V_SYNC_START] = pos & 0xFF;
        if (pos & 0x100)
                r7 |= 0x04;
        if (pos & 0x200)
                r7 |= 0x80;
        pos += vslen;
        par->crtc[VGA_CRTC_V_SYNC_END] = (pos & 0x0F) & ~0x10; /* disabled IRQ */
        pos += upper - 1; /* blank_end + 1 <= ytotal + 2 */
        par->crtc[VGA_CRTC_V_BLANK_END] = pos & 0xFF; /* 0x7F for original VGA,
                     but some SVGA chips requires all 8 bits to set */
        if (vxres >= 512)
                FAIL("vxres too long");
        par->crtc[VGA_CRTC_OFFSET] = vxres >> 1;
        if (mode & MODE_SKIP4)
                par->crtc[VGA_CRTC_UNDERLINE] = 0x5F;   /* 256, cfb8 */
        else
                par->crtc[VGA_CRTC_UNDERLINE] = 0x1F;   /* 16, vgap */
        par->crtc[VGA_CRTC_MODE] = rMode | ((mode & MODE_TEXT) ? 0xA3 : 0xE3);
        par->crtc[VGA_CRTC_LINE_COMPARE] = 0xFF;
        par->crtc[VGA_CRTC_OVERFLOW] = r7;

        par->vss = 0x00;        /* 3DA */

        par->misc = 0xE3;       /* enable CPU, ports 0x3Dx, positive sync */
        if (var->sync & FB_SYNC_HOR_HIGH_ACT)
                par->misc &= ~0x40;
        if (var->sync & FB_SYNC_VERT_HIGH_ACT)
                par->misc &= ~0x80;
        
        par->mode = mode;

        if (mode & MODE_8BPP)
                /* pixel clock == vga clock / 2 */
                vga16fb_clock_chip(par, &var->pixclock, info, 1, 2);
        else
                /* pixel clock == vga clock */
                vga16fb_clock_chip(par, &var->pixclock, info, 1, 1);
        
        var->red.offset = var->green.offset = var->blue.offset = 
        var->transp.offset = 0;
        var->red.length = var->green.length = var->blue.length =
                (par->isVGA) ? 6 : 2;
        var->transp.length = 0;
        var->activate = FB_ACTIVATE_NOW;
        var->height = -1;
        var->width = -1;
        var->accel_flags = 0;
        return 0;
}
#undef FAIL

static int vga16fb_set_par(struct fb_info *info)
{
        struct vga16fb_par *par = info->par;
        u8 gdc[VGA_GFX_C];
        u8 seq[VGA_SEQ_C];
        u8 atc[VGA_ATT_C];
        int fh, i;

        seq[VGA_SEQ_CLOCK_MODE] = 0x01 | par->clkdiv;
        if (par->mode & MODE_TEXT)
                seq[VGA_SEQ_PLANE_WRITE] = 0x03;
        else
                seq[VGA_SEQ_PLANE_WRITE] = 0x0F;
        seq[VGA_SEQ_CHARACTER_MAP] = 0x00;
        if (par->mode & MODE_TEXT)
                seq[VGA_SEQ_MEMORY_MODE] = 0x03;
        else if (par->mode & MODE_SKIP4)
                seq[VGA_SEQ_MEMORY_MODE] = 0x0E;
        else
                seq[VGA_SEQ_MEMORY_MODE] = 0x06;

        gdc[VGA_GFX_SR_VALUE] = 0x00;
        gdc[VGA_GFX_SR_ENABLE] = 0x00;
        gdc[VGA_GFX_COMPARE_VALUE] = 0x00;
        gdc[VGA_GFX_DATA_ROTATE] = 0x00;
        gdc[VGA_GFX_PLANE_READ] = 0;
        if (par->mode & MODE_TEXT) {
                gdc[VGA_GFX_MODE] = 0x10;
                gdc[VGA_GFX_MISC] = 0x06;
        } else {
                if (par->mode & MODE_CFB)
                        gdc[VGA_GFX_MODE] = 0x40;
                else
                        gdc[VGA_GFX_MODE] = 0x00;
                gdc[VGA_GFX_MISC] = 0x05;
        }
        gdc[VGA_GFX_COMPARE_MASK] = 0x0F;
        gdc[VGA_GFX_BIT_MASK] = 0xFF;

        for (i = 0x00; i < 0x10; i++)
                atc[i] = i;
        if (par->mode & MODE_TEXT)
                atc[VGA_ATC_MODE] = 0x04;
        else if (par->mode & MODE_8BPP)
                atc[VGA_ATC_MODE] = 0x41;
        else
                atc[VGA_ATC_MODE] = 0x81;
        atc[VGA_ATC_OVERSCAN] = 0x00;   /* 0 for EGA, 0xFF for VGA */
        atc[VGA_ATC_PLANE_ENABLE] = 0x0F;
        if (par->mode & MODE_8BPP)
                atc[VGA_ATC_PEL] = (info->var.xoffset & 3) << 1;
        else
                atc[VGA_ATC_PEL] = info->var.xoffset & 7;
        atc[VGA_ATC_COLOR_PAGE] = 0x00;
        
        if (par->mode & MODE_TEXT) {
                fh = 16; // FIXME !!! Fudge font height. 
                par->crtc[VGA_CRTC_MAX_SCAN] = (par->crtc[VGA_CRTC_MAX_SCAN] 
                                               & ~0x1F) | (fh - 1);
        }

        vga_io_w(VGA_MIS_W, vga_io_r(VGA_MIS_R) | 0x01);

        /* Enable graphics register modification */
        if (!par->isVGA) {
                vga_io_w(EGA_GFX_E0, 0x00);
                vga_io_w(EGA_GFX_E1, 0x01);
        }
        
        /* update misc output register */
        vga_io_w(VGA_MIS_W, par->misc);
        
        /* synchronous reset on */
        vga_io_wseq(0x00, 0x01);

        if (par->isVGA)
                vga_io_w(VGA_PEL_MSK, par->pel_msk);

        /* write sequencer registers */
        vga_io_wseq(VGA_SEQ_CLOCK_MODE, seq[VGA_SEQ_CLOCK_MODE] | 0x20);
        for (i = 2; i < VGA_SEQ_C; i++) {
                vga_io_wseq(i, seq[i]);
        }
        
        /* synchronous reset off */
        vga_io_wseq(0x00, 0x03);

        /* deprotect CRT registers 0-7 */
        vga_io_wcrt(VGA_CRTC_V_SYNC_END, par->crtc[VGA_CRTC_V_SYNC_END]);

        /* write CRT registers */
        for (i = 0; i < VGA_CRTC_REGS; i++) {
                vga_io_wcrt(i, par->crtc[i]);
        }
        
        /* write graphics controller registers */
        for (i = 0; i < VGA_GFX_C; i++) {
                vga_io_wgfx(i, gdc[i]);
        }
        
        /* write attribute controller registers */
        for (i = 0; i < VGA_ATT_C; i++) {
                vga_io_r(VGA_IS1_RC);           /* reset flip-flop */
                vga_io_wattr(i, atc[i]);
        }

        /* Wait for screen to stabilize. */
        mdelay(50);

        vga_io_wseq(VGA_SEQ_CLOCK_MODE, seq[VGA_SEQ_CLOCK_MODE]);

        vga_io_r(VGA_IS1_RC);
        vga_io_w(VGA_ATT_IW, 0x20);

        vga16fb_update_fix(info);
        return 0;
}

static void ega16_setpalette(int regno, unsigned red, unsigned green, unsigned blue)
{
        static const unsigned char map[] = { 000, 001, 010, 011 };
        int val;
        
        if (regno >= 16)
                return;
        val = map[red>>14] | ((map[green>>14]) << 1) | ((map[blue>>14]) << 2);
        vga_io_r(VGA_IS1_RC);   /* ! 0x3BA */
        vga_io_wattr(regno, val);
        vga_io_r(VGA_IS1_RC);   /* some clones need it */
        vga_io_w(VGA_ATT_IW, 0x20); /* unblank screen */
}

static void vga16_setpalette(int regno, unsigned red, unsigned green, unsigned blue)
{
        outb(regno,       VGA_PEL_IW);
        outb(red   >> 10, VGA_PEL_D);
        outb(green >> 10, VGA_PEL_D);
        outb(blue  >> 10, VGA_PEL_D);
}

static int vga16fb_setcolreg(unsigned regno, unsigned red, unsigned green,
                             unsigned blue, unsigned transp,
                             struct fb_info *info)
{
        struct vga16fb_par *par = info->par;
        int gray;

        /*
         *  Set a single color register. The values supplied are
         *  already rounded down to the hardware's capabilities
         *  (according to the entries in the `var' structure). Return
         *  != 0 for invalid regno.
         */
        
        if (regno >= 256)
                return 1;

        gray = info->var.grayscale;
        
        if (gray) {
                /* gray = 0.30*R + 0.59*G + 0.11*B */
                red = green = blue = (red * 77 + green * 151 + blue * 28) >> 8;
        }
        if (par->isVGA) 
                vga16_setpalette(regno,red,green,blue);
        else
                ega16_setpalette(regno,red,green,blue);
        return 0;
}

static int vga16fb_pan_display(struct fb_var_screeninfo *var,
                               struct fb_info *info) 
{
        vga16fb_pan_var(info, var);
        return 0;
}

/* The following VESA blanking code is taken from vgacon.c.  The VGA
   blanking code was originally by Huang shi chao, and modified by
   Christoph Rimek (chrimek@toppoint.de) and todd j. derr
   (tjd@barefoot.org) for Linux. */

static void vga_vesa_blank(struct vga16fb_par *par, int mode)
{
        unsigned char SeqCtrlIndex = vga_io_r(VGA_SEQ_I);
        unsigned char CrtCtrlIndex = vga_io_r(VGA_CRT_IC);
        
        /* save original values of VGA controller registers */
        if(!par->vesa_blanked) {
                par->vga_state.CrtMiscIO = vga_io_r(VGA_MIS_R);
                //sti();

                par->vga_state.HorizontalTotal = vga_io_rcrt(0x00);     /* HorizontalTotal */
                par->vga_state.HorizDisplayEnd = vga_io_rcrt(0x01);     /* HorizDisplayEnd */
                par->vga_state.StartHorizRetrace = vga_io_rcrt(0x04);   /* StartHorizRetrace */
                par->vga_state.EndHorizRetrace = vga_io_rcrt(0x05);     /* EndHorizRetrace */
                par->vga_state.Overflow = vga_io_rcrt(0x07);            /* Overflow */
                par->vga_state.StartVertRetrace = vga_io_rcrt(0x10);    /* StartVertRetrace */
                par->vga_state.EndVertRetrace = vga_io_rcrt(0x11);      /* EndVertRetrace */
                par->vga_state.ModeControl = vga_io_rcrt(0x17); /* ModeControl */
                par->vga_state.ClockingMode = vga_io_rseq(0x01);        /* ClockingMode */
        }

        /* assure that video is enabled */
        /* "0x20" is VIDEO_ENABLE_bit in register 01 of sequencer */
        vga_io_wseq(0x01, par->vga_state.ClockingMode | 0x20);

        /* test for vertical retrace in process.... */
        if ((par->vga_state.CrtMiscIO & 0x80) == 0x80)
                vga_io_w(VGA_MIS_W, par->vga_state.CrtMiscIO & 0xef);

        /*
         * Set <End of vertical retrace> to minimum (0) and
         * <Start of vertical Retrace> to maximum (incl. overflow)
         * Result: turn off vertical sync (VSync) pulse.
         */
        if (mode & FB_BLANK_VSYNC_SUSPEND) {
                vga_io_wcrt(VGA_CRTC_V_SYNC_START, 0xff);
                vga_io_wcrt(VGA_CRTC_V_SYNC_END, 0x40);
                /* bits 9,10 of vert. retrace */
                vga_io_wcrt(VGA_CRTC_OVERFLOW, par->vga_state.Overflow | 0x84);
        }

        if (mode & FB_BLANK_HSYNC_SUSPEND) {
                /*
                 * Set <End of horizontal retrace> to minimum (0) and
                 *  <Start of horizontal Retrace> to maximum
                 * Result: turn off horizontal sync (HSync) pulse.
                 */
                vga_io_wcrt(VGA_CRTC_H_SYNC_START, 0xff);
                vga_io_wcrt(VGA_CRTC_H_SYNC_END, 0x00);
        }

        /* restore both index registers */
        outb_p(SeqCtrlIndex, VGA_SEQ_I);
        outb_p(CrtCtrlIndex, VGA_CRT_IC);
}

static void vga_vesa_unblank(struct vga16fb_par *par)
{
        unsigned char SeqCtrlIndex = vga_io_r(VGA_SEQ_I);
        unsigned char CrtCtrlIndex = vga_io_r(VGA_CRT_IC);
        
        /* restore original values of VGA controller registers */
        vga_io_w(VGA_MIS_W, par->vga_state.CrtMiscIO);

        /* HorizontalTotal */
        vga_io_wcrt(0x00, par->vga_state.HorizontalTotal);
        /* HorizDisplayEnd */
        vga_io_wcrt(0x01, par->vga_state.HorizDisplayEnd);
        /* StartHorizRetrace */
        vga_io_wcrt(0x04, par->vga_state.StartHorizRetrace);
        /* EndHorizRetrace */
        vga_io_wcrt(0x05, par->vga_state.EndHorizRetrace);
        /* Overflow */
        vga_io_wcrt(0x07, par->vga_state.Overflow);
        /* StartVertRetrace */
        vga_io_wcrt(0x10, par->vga_state.StartVertRetrace);
        /* EndVertRetrace */
        vga_io_wcrt(0x11, par->vga_state.EndVertRetrace);
        /* ModeControl */
        vga_io_wcrt(0x17, par->vga_state.ModeControl);
        /* ClockingMode */
        vga_io_wseq(0x01, par->vga_state.ClockingMode);

        /* restore index/control registers */
        vga_io_w(VGA_SEQ_I, SeqCtrlIndex);
        vga_io_w(VGA_CRT_IC, CrtCtrlIndex);
}

static void vga_pal_blank(void)
{
        int i;

        for (i=0; i<16; i++) {
                outb_p(i, VGA_PEL_IW);
                outb_p(0, VGA_PEL_D);
                outb_p(0, VGA_PEL_D);
                outb_p(0, VGA_PEL_D);
        }
}

/* 0 unblank, 1 blank, 2 no vsync, 3 no hsync, 4 off */
static int vga16fb_blank(int blank, struct fb_info *info)
{
        struct vga16fb_par *par = info->par;

        switch (blank) {
        case FB_BLANK_UNBLANK:                          /* Unblank */
                if (par->vesa_blanked) {
                        vga_vesa_unblank(par);
                        par->vesa_blanked = 0;
                }
                if (par->palette_blanked) {
                        par->palette_blanked = 0;
                }
                break;
        case FB_BLANK_NORMAL:                           /* blank */
                vga_pal_blank();
                par->palette_blanked = 1;
                break;
        default:                        /* VESA blanking */
                vga_vesa_blank(par, blank);
                par->vesa_blanked = 1;
                break;
        }
        return 0;
}

static void vga_8planes_fillrect(struct fb_info *info, const struct fb_fillrect *rect)
{
        u32 dx = rect->dx, width = rect->width;
        char oldindex = getindex();
        char oldmode = setmode(0x40);
        char oldmask = selectmask();
        int line_ofs, height;
        char oldop, oldsr;
        char __iomem *where;

        dx /= 4;
        where = info->screen_base + dx + rect->dy * info->fix.line_length;

        if (rect->rop == ROP_COPY) {
                oldop = setop(0);
                oldsr = setsr(0);

                width /= 4;
                line_ofs = info->fix.line_length - width;
                setmask(0xff);

                height = rect->height;

                while (height--) {
                        int x;

                        /* we can do memset... */
                        for (x = width; x > 0; --x) {
                                writeb(rect->color, where);
                                where++;
                        }
                        where += line_ofs;
                }
        } else {
                char oldcolor = setcolor(0xf);
                int y;

                oldop = setop(0x18);
                oldsr = setsr(0xf);
                setmask(0x0F);
                for (y = 0; y < rect->height; y++) {
                        rmw(where);
                        rmw(where+1);
                        where += info->fix.line_length;
                }
                setcolor(oldcolor);
        }
        setmask(oldmask);
        setsr(oldsr);
        setop(oldop);
        setmode(oldmode);
        setindex(oldindex);
}

static void vga16fb_fillrect(struct fb_info *info, const struct fb_fillrect *rect)
{
        int x, x2, y2, vxres, vyres, width, height, line_ofs;
        char __iomem *dst;

        vxres = info->var.xres_virtual;
        vyres = info->var.yres_virtual;

        if (!rect->width || !rect->height || rect->dx > vxres || rect->dy > vyres)
                return;

        /* We could use hardware clipping but on many cards you get around
         * hardware clipping by writing to framebuffer directly. */

        x2 = rect->dx + rect->width;
        y2 = rect->dy + rect->height;
        x2 = x2 < vxres ? x2 : vxres;
        y2 = y2 < vyres ? y2 : vyres;
        width = x2 - rect->dx;

        switch (info->fix.type) {
        case FB_TYPE_VGA_PLANES:
                if (info->fix.type_aux == FB_AUX_VGA_PLANES_VGA4) {

                        height = y2 - rect->dy;
                        width = rect->width/8;

                        line_ofs = info->fix.line_length - width;
                        dst = info->screen_base + (rect->dx/8) + rect->dy * info->fix.line_length;

                        switch (rect->rop) {
                        case ROP_COPY:
                                setmode(0);
                                setop(0);
                                setsr(0xf);
                                setcolor(rect->color);
                                selectmask();

                                setmask(0xff);

                                while (height--) {
                                        for (x = 0; x < width; x++) {
                                                writeb(0, dst);
                                                dst++;
                                        }
                                        dst += line_ofs;
                                }
                                break;
                        case ROP_XOR:
                                setmode(0);
                                setop(0x18);
                                setsr(0xf);
                                setcolor(0xf);
                                selectmask();

                                setmask(0xff);
                                while (height--) {
                                        for (x = 0; x < width; x++) {
                                                rmw(dst);
                                                dst++;
                                        }
                                        dst += line_ofs;
                                }
                                break;
                        }
                } else 
                        vga_8planes_fillrect(info, rect);
                break;
        case FB_TYPE_PACKED_PIXELS:
        default:
                cfb_fillrect(info, rect);
                break;
        }
}

static void vga_8planes_copyarea(struct fb_info *info, const struct fb_copyarea *area)
{
        char oldindex = getindex();
        char oldmode = setmode(0x41);
        char oldop = setop(0);
        char oldsr = setsr(0xf);
        int height, line_ofs, x;
        u32 sx, dx, width;
        char __iomem *dest;
        char __iomem *src;

        height = area->height;

        sx = area->sx / 4;
        dx = area->dx / 4;
        width = area->width / 4;

        if (area->dy < area->sy || (area->dy == area->sy && dx < sx)) {
                line_ofs = info->fix.line_length - width;
                dest = info->screen_base + dx + area->dy * info->fix.line_length;
                src = info->screen_base + sx + area->sy * info->fix.line_length;
                while (height--) {
                        for (x = 0; x < width; x++) {
                                readb(src);
                                writeb(0, dest);
                                src++;

                                dest++;
                        }
                        src += line_ofs;
                        dest += line_ofs;
                }
        } else {
                line_ofs = info->fix.line_length - width;
                dest = info->screen_base + dx + width +
                        (area->dy + height - 1) * info->fix.line_length;
                src = info->screen_base + sx + width +
                        (area->sy + height - 1) * info->fix.line_length;
                while (height--) {
                        for (x = 0; x < width; x++) {
                                --src;
                                --dest;
                                readb(src);
                                writeb(0, dest);
                        }
                        src -= line_ofs;
                        dest -= line_ofs;
                }
        }

        setsr(oldsr);
        setop(oldop);
        setmode(oldmode);
        setindex(oldindex);
}

static void vga16fb_copyarea(struct fb_info *info, const struct fb_copyarea *area)
{
        u32 dx = area->dx, dy = area->dy, sx = area->sx, sy = area->sy; 
        int x, x2, y2, old_dx, old_dy, vxres, vyres;
        int height, width, line_ofs;
        char __iomem *dst = NULL;
        char __iomem *src = NULL;

        vxres = info->var.xres_virtual;
        vyres = info->var.yres_virtual;

        if (area->dx > vxres || area->sx > vxres || area->dy > vyres ||
            area->sy > vyres)
                return;

        /* clip the destination */
        old_dx = area->dx;
        old_dy = area->dy;

        /*
         * We could use hardware clipping but on many cards you get around
         * hardware clipping by writing to framebuffer directly.
         */
        x2 = area->dx + area->width;
        y2 = area->dy + area->height;
        dx = area->dx > 0 ? area->dx : 0;
        dy = area->dy > 0 ? area->dy : 0;
        x2 = x2 < vxres ? x2 : vxres;
        y2 = y2 < vyres ? y2 : vyres;
        width = x2 - dx;
        height = y2 - dy;

        if (sx + dx < old_dx || sy + dy < old_dy)
                return;

        /* update sx1,sy1 */
        sx += (dx - old_dx);
        sy += (dy - old_dy);

        /* the source must be completely inside the virtual screen */
        if (sx + width > vxres || sy + height > vyres)
                return;

        switch (info->fix.type) {
        case FB_TYPE_VGA_PLANES:
                if (info->fix.type_aux == FB_AUX_VGA_PLANES_VGA4) {
                        width = width/8;
                        line_ofs = info->fix.line_length - width;

                        setmode(1);
                        setop(0);
                        setsr(0xf);

                        if (dy < sy || (dy == sy && dx < sx)) {
                                dst = info->screen_base + (dx/8) + dy * info->fix.line_length;
                                src = info->screen_base + (sx/8) + sy * info->fix.line_length;
                                while (height--) {
                                        for (x = 0; x < width; x++) {
                                                readb(src);
                                                writeb(0, dst);
                                                dst++;
                                                src++;
                                        }
                                        src += line_ofs;
                                        dst += line_ofs;
                                }
                        } else {
                                dst = info->screen_base + (dx/8) + width + 
                                        (dy + height - 1) * info->fix.line_length;
                                src = info->screen_base + (sx/8) + width + 
                                        (sy + height  - 1) * info->fix.line_length;
                                while (height--) {
                                        for (x = 0; x < width; x++) {
                                                dst--;
                                                src--;
                                                readb(src);
                                                writeb(0, dst);
                                        }
                                        src -= line_ofs;
                                        dst -= line_ofs;
                                }
                        }
                } else 
                        vga_8planes_copyarea(info, area);
                break;
        case FB_TYPE_PACKED_PIXELS:
        default:
                cfb_copyarea(info, area);
                break;
        }
}

#define TRANS_MASK_LOW  {0x0,0x8,0x4,0xC,0x2,0xA,0x6,0xE,0x1,0x9,0x5,0xD,0x3,0xB,0x7,0xF}
#define TRANS_MASK_HIGH {0x000, 0x800, 0x400, 0xC00, 0x200, 0xA00, 0x600, 0xE00, \
                         0x100, 0x900, 0x500, 0xD00, 0x300, 0xB00, 0x700, 0xF00}

#if defined(__LITTLE_ENDIAN)
static const u16 transl_l[] = TRANS_MASK_LOW;
static const u16 transl_h[] = TRANS_MASK_HIGH;
#elif defined(__BIG_ENDIAN)
static const u16 transl_l[] = TRANS_MASK_HIGH;
static const u16 transl_h[] = TRANS_MASK_LOW;
#else
#error "Only __BIG_ENDIAN and __LITTLE_ENDIAN are supported in vga-planes"
#endif

static void vga_8planes_imageblit(struct fb_info *info, const struct fb_image *image)
{
        char oldindex = getindex();
        char oldmode = setmode(0x40);
        char oldop = setop(0);
        char oldsr = setsr(0);
        char oldmask = selectmask();
        const unsigned char *cdat = image->data;
        u32 dx = image->dx;
        char __iomem *where;
        int y;

        dx /= 4;
        where = info->screen_base + dx + image->dy * info->fix.line_length;

        setmask(0xff);
        writeb(image->bg_color, where);
        readb(where);
        selectmask();
        setmask(image->fg_color ^ image->bg_color);
        setmode(0x42);
        setop(0x18);
        for (y = 0; y < image->height; y++, where += info->fix.line_length)
                writew(transl_h[cdat[y]&0xF] | transl_l[cdat[y] >> 4], where);
        setmask(oldmask);
        setsr(oldsr);
        setop(oldop);
        setmode(oldmode);
        setindex(oldindex);
}

static void vga_imageblit_expand(struct fb_info *info, const struct fb_image *image)
{
        char __iomem *where = info->screen_base + (image->dx/8) +
                image->dy * info->fix.line_length;
        struct vga16fb_par *par = info->par;
        char *cdat = (char *) image->data;
        char __iomem *dst;
        int x, y;

        switch (info->fix.type) {
        case FB_TYPE_VGA_PLANES:
                if (info->fix.type_aux == FB_AUX_VGA_PLANES_VGA4) {
                        if (par->isVGA) {
                                setmode(2);
                                setop(0);
                                setsr(0xf);
                                setcolor(image->fg_color);
                                selectmask();
                                
                                setmask(0xff);
                                writeb(image->bg_color, where);
                                rmb();
                                readb(where); /* fill latches */
                                setmode(3);
                                wmb();
                                for (y = 0; y < image->height; y++) {
                                        dst = where;
                                        for (x = image->width/8; x--;) 
                                                writeb(*cdat++, dst++);
                                        where += info->fix.line_length;
                                }
                                wmb();
                        } else {
                                setmode(0);
                                setop(0);
                                setsr(0xf);
                                setcolor(image->bg_color);
                                selectmask();
                                
                                setmask(0xff);
                                for (y = 0; y < image->height; y++) {
                                        dst = where;
                                        for (x=image->width/8; x--;){
                                                rmw(dst);
                                                setcolor(image->fg_color);
                                                selectmask();
                                                if (*cdat) {
                                                        setmask(*cdat++);
                                                        rmw(dst++);
                                                }
                                        }
                                        where += info->fix.line_length;
                                }
                        }
                } else 
                        vga_8planes_imageblit(info, image);
                break;
        case FB_TYPE_PACKED_PIXELS:
        default:
                cfb_imageblit(info, image);
                break;
        }
}

static void vga_imageblit_color(struct fb_info *info, const struct fb_image *image)
{
        /*
         * Draw logo 
         */
        struct vga16fb_par *par = info->par;
        char __iomem *where =
                info->screen_base + image->dy * info->fix.line_length +
                image->dx/8;
        const char *cdat = image->data;
        char __iomem *dst;
        int x, y;

        switch (info->fix.type) {
        case FB_TYPE_VGA_PLANES:
                if (info->fix.type_aux == FB_AUX_VGA_PLANES_VGA4 &&
                    par->isVGA) {
                        setsr(0xf);
                        setop(0);
                        setmode(0);
                        
                        for (y = 0; y < image->height; y++) {
                                for (x = 0; x < image->width; x++) {
                                        dst = where + x/8;

                                        setcolor(*cdat);
                                        selectmask();
                                        setmask(1 << (7 - (x % 8)));
                                        fb_readb(dst);
                                        fb_writeb(0, dst);

                                        cdat++;
                                }
                                where += info->fix.line_length;
                        }
                }
                break;
        case FB_TYPE_PACKED_PIXELS:
                cfb_imageblit(info, image);
                break;
        default:
                break;
        }
}
                                
static void vga16fb_imageblit(struct fb_info *info, const struct fb_image *image)
{
        if (image->depth == 1)
                vga_imageblit_expand(info, image);
        else
                vga_imageblit_color(info, image);
}

static void vga16fb_destroy(struct fb_info *info)
{
        iounmap(info->screen_base);
        fb_dealloc_cmap(&info->cmap);
        /* XXX unshare VGA regions */
        framebuffer_release(info);
}

static const struct fb_ops vga16fb_ops = {
        .owner          = THIS_MODULE,
        .fb_open        = vga16fb_open,
        .fb_release     = vga16fb_release,
        .fb_destroy     = vga16fb_destroy,
        .fb_check_var   = vga16fb_check_var,
        .fb_set_par     = vga16fb_set_par,
        .fb_setcolreg   = vga16fb_setcolreg,
        .fb_pan_display = vga16fb_pan_display,
        .fb_blank       = vga16fb_blank,
        .fb_fillrect    = vga16fb_fillrect,
        .fb_copyarea    = vga16fb_copyarea,
        .fb_imageblit   = vga16fb_imageblit,
};

#ifndef MODULE
static int __init vga16fb_setup(char *options)
{
        char *this_opt;
        
        if (!options || !*options)
                return 0;
        
        while ((this_opt = strsep(&options, ",")) != NULL) {
                if (!*this_opt) continue;
        }
        return 0;
}
#endif

static int vga16fb_probe(struct platform_device *dev)
{
        struct fb_info *info;
        struct vga16fb_par *par;
        int i;
        int ret = 0;

        printk(KERN_DEBUG "vga16fb: initializing\n");
        info = framebuffer_alloc(sizeof(struct vga16fb_par), &dev->dev);

        if (!info) {
                ret = -ENOMEM;
                goto err_fb_alloc;
        }
        info->apertures = alloc_apertures(1);
        if (!info->apertures) {
                ret = -ENOMEM;
                goto err_ioremap;
        }

        /* XXX share VGA_FB_PHYS and I/O region with vgacon and others */
        info->screen_base = (void __iomem *)VGA_MAP_MEM(VGA_FB_PHYS, 0);

        if (!info->screen_base) {
                printk(KERN_ERR "vga16fb: unable to map device\n");
                ret = -ENOMEM;
                goto err_ioremap;
        }

        printk(KERN_INFO "vga16fb: mapped to 0x%p\n", info->screen_base);
        par = info->par;

        par->isVGA = screen_info.orig_video_isVGA;
        par->palette_blanked = 0;
        par->vesa_blanked = 0;

        i = par->isVGA? 6 : 2;
        
        vga16fb_defined.red.length   = i;
        vga16fb_defined.green.length = i;
        vga16fb_defined.blue.length  = i;       

        /* name should not depend on EGA/VGA */
        info->fbops = &vga16fb_ops;
        info->var = vga16fb_defined;
        info->fix = vga16fb_fix;
        /* supports rectangles with widths of multiples of 8 */
        info->pixmap.blit_x = 1 << 7 | 1 << 15 | 1 << 23 | 1 << 31;
        info->flags = FBINFO_FLAG_DEFAULT | FBINFO_MISC_FIRMWARE |
                FBINFO_HWACCEL_YPAN;

        i = (info->var.bits_per_pixel == 8) ? 256 : 16;
        ret = fb_alloc_cmap(&info->cmap, i, 0);
        if (ret) {
                printk(KERN_ERR "vga16fb: unable to allocate colormap\n");
                ret = -ENOMEM;
                goto err_alloc_cmap;
        }

        if (vga16fb_check_var(&info->var, info)) {
                printk(KERN_ERR "vga16fb: unable to validate variable\n");
                ret = -EINVAL;
                goto err_check_var;
        }

        vga16fb_update_fix(info);

        info->apertures->ranges[0].base = VGA_FB_PHYS;
        info->apertures->ranges[0].size = VGA_FB_PHYS_LEN;

        if (register_framebuffer(info) < 0) {
                printk(KERN_ERR "vga16fb: unable to register framebuffer\n");
                ret = -EINVAL;
                goto err_check_var;
        }

        fb_info(info, "%s frame buffer device\n", info->fix.id);
        platform_set_drvdata(dev, info);

        return 0;

 err_check_var:
        fb_dealloc_cmap(&info->cmap);
 err_alloc_cmap:
        iounmap(info->screen_base);
 err_ioremap:
        framebuffer_release(info);
 err_fb_alloc:
        return ret;
}

static int vga16fb_remove(struct platform_device *dev)
{
        struct fb_info *info = platform_get_drvdata(dev);

        if (info)
                unregister_framebuffer(info);

        return 0;
}

static struct platform_driver vga16fb_driver = {
        .probe = vga16fb_probe,
        .remove = vga16fb_remove,
        .driver = {
                .name = "vga16fb",
        },
};

static struct platform_device *vga16fb_device;

static int __init vga16fb_init(void)
{
        int ret;
#ifndef MODULE
        char *option = NULL;

        if (fb_get_options("vga16fb", &option))
                return -ENODEV;

        vga16fb_setup(option);
#endif

        ret = check_mode_supported();
        if (ret)
                return ret;

        ret = platform_driver_register(&vga16fb_driver);

        if (!ret) {
                vga16fb_device = platform_device_alloc("vga16fb", 0);

                if (vga16fb_device)
                        ret = platform_device_add(vga16fb_device);
                else
                        ret = -ENOMEM;

                if (ret) {
                        platform_device_put(vga16fb_device);
                        platform_driver_unregister(&vga16fb_driver);
                }
        }

        return ret;
}

static void __exit vga16fb_exit(void)
{
        platform_device_unregister(vga16fb_device);
        platform_driver_unregister(&vga16fb_driver);
}

MODULE_DESCRIPTION("Legacy VGA framebuffer device driver");
MODULE_LICENSE("GPL");
module_init(vga16fb_init);
module_exit(vga16fb_exit);