/*
 * linux/drivers/video/atafb.c -- Atari builtin chipset frame buffer device
 *
 *  Copyright (C) 1994 Martin Schaller & Roman Hodek
 *
 * 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.
 *
 * History:
 *   - 03 Jan 95: Original version by Martin Schaller: The TT driver and
 *                all the device independent stuff
 *   - 09 Jan 95: Roman: I've added the hardware abstraction (hw_switch)
 *                and wrote the Falcon, ST(E), and External drivers
 *                based on the original TT driver.
 *   - 07 May 95: Martin: Added colormap operations for the external driver
 *   - 21 May 95: Martin: Added support for overscan
 *		  Andreas: some bug fixes for this
 *   -    Jul 95: Guenther Kelleter <guenther@pool.informatik.rwth-aachen.de>:
 *                Programmable Falcon video modes
 *                (thanks to Christian Cartus for documentation
 *                of VIDEL registers).
 *   - 27 Dec 95: Guenther: Implemented user definable video modes "user[0-7]"
 *                on minor 24...31. "user0" may be set on commandline by
 *                "R<x>;<y>;<depth>". (Makes sense only on Falcon)
 *                Video mode switch on Falcon now done at next VBL interrupt
 *                to avoid the annoying right shift of the screen.
 *   - 23 Sep 97: Juergen: added xres_virtual for cards like ProMST
 *                The external-part is legacy, therefore hardware-specific
 *                functions like panning/hardwarescrolling/blanking isn't
 *				  supported.
 *   - 29 Sep 97: Juergen: added Romans suggestion for pan_display
 *				  (var->xoffset was changed even if no set_screen_base avail.)
 *	 - 05 Oct 97: Juergen: extfb (PACKED_PIXEL) is FB_PSEUDOCOLOR 'cause
 *				  we know how to set the colors
 *				  ext_*palette: read from ext_colors (former MV300_colors)
 *							    write to ext_colors and RAMDAC
 *
 * To do:
 *   - For the Falcon it is not possible to set random video modes on
 *     SM124 and SC/TV, only the bootup resolution is supported.
 *
 */

#define ATAFB_TT
#define ATAFB_STE
#define ATAFB_EXT
#define ATAFB_FALCON

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/interrupt.h>

#include <asm/setup.h>
#include <linux/uaccess.h>
#include <asm/pgtable.h>
#include <asm/irq.h>
#include <asm/io.h>

#include <asm/atarihw.h>
#include <asm/atariints.h>
#include <asm/atari_stram.h>

#include <linux/fb.h>
#include <asm/atarikb.h>

#include "c2p.h"
#include "atafb.h"

#define SWITCH_ACIA 0x01		/* modes for switch on OverScan */
#define SWITCH_SND6 0x40
#define SWITCH_SND7 0x80
#define SWITCH_NONE 0x00


#define up(x, r) (((x) + (r) - 1) & ~((r)-1))

	/*
	 * Interface to the world
	 */

static int atafb_check_var(struct fb_var_screeninfo *var, struct fb_info *info);
static int atafb_set_par(struct fb_info *info);
static int atafb_setcolreg(unsigned int regno, unsigned int red, unsigned int green,
			   unsigned int blue, unsigned int transp,
			   struct fb_info *info);
static int atafb_blank(int blank, struct fb_info *info);
static int atafb_pan_display(struct fb_var_screeninfo *var,
			     struct fb_info *info);
static void atafb_fillrect(struct fb_info *info,
			   const struct fb_fillrect *rect);
static void atafb_copyarea(struct fb_info *info,
			   const struct fb_copyarea *region);
static void atafb_imageblit(struct fb_info *info, const struct fb_image *image);
static int atafb_ioctl(struct fb_info *info, unsigned int cmd,
		       unsigned long arg);


static int default_par;		/* default resolution (0=none) */

static unsigned long default_mem_req;

static int hwscroll = -1;

static int use_hwscroll = 1;

static int sttt_xres = 640, st_yres = 400, tt_yres = 480;
static int sttt_xres_virtual = 640, sttt_yres_virtual = 400;
static int ovsc_offset, ovsc_addlen;

	/*
	 * Hardware parameters for current mode
	 */

static struct atafb_par {
	void *screen_base;
	int yres_virtual;
	u_long next_line;
	u_long next_plane;
#if defined ATAFB_TT || defined ATAFB_STE
	union {
		struct {
			int mode;
			int sync;
		} tt, st;
#endif
#ifdef ATAFB_FALCON
		struct falcon_hw {
			/* Here are fields for storing a video mode, as direct
			 * parameters for the hardware.
			 */
			short sync;
			short line_width;
			short line_offset;
			short st_shift;
			short f_shift;
			short vid_control;
			short vid_mode;
			short xoffset;
			short hht, hbb, hbe, hdb, hde, hss;
			short vft, vbb, vbe, vdb, vde, vss;
			/* auxiliary information */
			short mono;
			short ste_mode;
			short bpp;
		} falcon;
#endif
		/* Nothing needed for external mode */
	} hw;
} current_par;

/* Don't calculate an own resolution, and thus don't change the one found when
 * booting (currently used for the Falcon to keep settings for internal video
 * hardware extensions (e.g. ScreenBlaster)  */
static int DontCalcRes = 0;

#ifdef ATAFB_FALCON
#define HHT hw.falcon.hht
#define HBB hw.falcon.hbb
#define HBE hw.falcon.hbe
#define HDB hw.falcon.hdb
#define HDE hw.falcon.hde
#define HSS hw.falcon.hss
#define VFT hw.falcon.vft
#define VBB hw.falcon.vbb
#define VBE hw.falcon.vbe
#define VDB hw.falcon.vdb
#define VDE hw.falcon.vde
#define VSS hw.falcon.vss
#define VCO_CLOCK25		0x04
#define VCO_CSYPOS		0x10
#define VCO_VSYPOS		0x20
#define VCO_HSYPOS		0x40
#define VCO_SHORTOFFS	0x100
#define VMO_DOUBLE		0x01
#define VMO_INTER		0x02
#define VMO_PREMASK		0x0c
#endif

static struct fb_info fb_info = {
	.fix = {
		.id	= "Atari ",
		.visual	= FB_VISUAL_PSEUDOCOLOR,
		.accel	= FB_ACCEL_NONE,
	}
};

static void *screen_base;	/* base address of screen */
static void *real_screen_base;	/* (only for Overscan) */

static int screen_len;

static int current_par_valid;

static int mono_moni;


#ifdef ATAFB_EXT

/* external video handling */
static unsigned int external_xres;
static unsigned int external_xres_virtual;
static unsigned int external_yres;

/*
 * not needed - atafb will never support panning/hardwarescroll with external
 * static unsigned int external_yres_virtual;
 */
static unsigned int external_depth;
static int external_pmode;
static void *external_addr;
static unsigned long external_len;
static unsigned long external_vgaiobase;
static unsigned int external_bitspercol = 6;

/*
 * JOE <joe@amber.dinoco.de>:
 * added card type for external driver, is only needed for
 * colormap handling.
 */
enum cardtype { IS_VGA, IS_MV300 };
static enum cardtype external_card_type = IS_VGA;

/*
 * The MV300 mixes the color registers. So we need an array of munged
 * indices in order to access the correct reg.
 */
static int MV300_reg_1bit[2] = {
	0, 1
};
static int MV300_reg_4bit[16] = {
	0, 8, 4, 12, 2, 10, 6, 14, 1, 9, 5, 13, 3, 11, 7, 15
};
static int MV300_reg_8bit[256] = {
	0, 128, 64, 192, 32, 160, 96, 224, 16, 144, 80, 208, 48, 176, 112, 240,
	8, 136, 72, 200, 40, 168, 104, 232, 24, 152, 88, 216, 56, 184, 120, 248,
	4, 132, 68, 196, 36, 164, 100, 228, 20, 148, 84, 212, 52, 180, 116, 244,
	12, 140, 76, 204, 44, 172, 108, 236, 28, 156, 92, 220, 60, 188, 124, 252,
	2, 130, 66, 194, 34, 162, 98, 226, 18, 146, 82, 210, 50, 178, 114, 242,
	10, 138, 74, 202, 42, 170, 106, 234, 26, 154, 90, 218, 58, 186, 122, 250,
	6, 134, 70, 198, 38, 166, 102, 230, 22, 150, 86, 214, 54, 182, 118, 246,
	14, 142, 78, 206, 46, 174, 110, 238, 30, 158, 94, 222, 62, 190, 126, 254,
	1, 129, 65, 193, 33, 161, 97, 225, 17, 145, 81, 209, 49, 177, 113, 241,
	9, 137, 73, 201, 41, 169, 105, 233, 25, 153, 89, 217, 57, 185, 121, 249,
	5, 133, 69, 197, 37, 165, 101, 229, 21, 149, 85, 213, 53, 181, 117, 245,
	13, 141, 77, 205, 45, 173, 109, 237, 29, 157, 93, 221, 61, 189, 125, 253,
	3, 131, 67, 195, 35, 163, 99, 227, 19, 147, 83, 211, 51, 179, 115, 243,
	11, 139, 75, 203, 43, 171, 107, 235, 27, 155, 91, 219, 59, 187, 123, 251,
	7, 135, 71, 199, 39, 167, 103, 231, 23, 151, 87, 215, 55, 183, 119, 247,
	15, 143, 79, 207, 47, 175, 111, 239, 31, 159, 95, 223, 63, 191, 127, 255
};

static int *MV300_reg = MV300_reg_8bit;
#endif /* ATAFB_EXT */


static int inverse;

extern int fontheight_8x8;
extern int fontwidth_8x8;
extern unsigned char fontdata_8x8[];

extern int fontheight_8x16;
extern int fontwidth_8x16;
extern unsigned char fontdata_8x16[];

/*
 * struct fb_ops {
 *	* open/release and usage marking
 *	struct module *owner;
 *	int (*fb_open)(struct fb_info *info, int user);
 *	int (*fb_release)(struct fb_info *info, int user);
 *
 *	* For framebuffers with strange non linear layouts or that do not
 *	* work with normal memory mapped access
 *	ssize_t (*fb_read)(struct file *file, char __user *buf, size_t count, loff_t *ppos);
 *	ssize_t (*fb_write)(struct file *file, const char __user *buf, size_t count, loff_t *ppos);
 *
 *	* checks var and eventually tweaks it to something supported,
 *	* DOES NOT MODIFY PAR *
 *	int (*fb_check_var)(struct fb_var_screeninfo *var, struct fb_info *info);
 *
 *	* set the video mode according to info->var *
 *	int (*fb_set_par)(struct fb_info *info);
 *
 *	* set color register *
 *	int (*fb_setcolreg)(unsigned int regno, unsigned int red, unsigned int green,
 *			    unsigned int blue, unsigned int transp, struct fb_info *info);
 *
 *	* set color registers in batch *
 *	int (*fb_setcmap)(struct fb_cmap *cmap, struct fb_info *info);
 *
 *	* blank display *
 *	int (*fb_blank)(int blank, struct fb_info *info);
 *
 *	* pan display *
 *	int (*fb_pan_display)(struct fb_var_screeninfo *var, struct fb_info *info);
 *
 *	*** The meat of the drawing engine ***
 *	* Draws a rectangle *
 *	void (*fb_fillrect) (struct fb_info *info, const struct fb_fillrect *rect);
 *	* Copy data from area to another *
 *	void (*fb_copyarea) (struct fb_info *info, const struct fb_copyarea *region);
 *	* Draws a image to the display *
 *	void (*fb_imageblit) (struct fb_info *info, const struct fb_image *image);
 *
 *	* Draws cursor *
 *	int (*fb_cursor) (struct fb_info *info, struct fb_cursor *cursor);
 *
 *	* Rotates the display *
 *	void (*fb_rotate)(struct fb_info *info, int angle);
 *
 *	* wait for blit idle, optional *
 *	int (*fb_sync)(struct fb_info *info);
 *
 *	* perform fb specific ioctl (optional) *
 *	int (*fb_ioctl)(struct fb_info *info, unsigned int cmd,
 *			unsigned long arg);
 *
 *	* Handle 32bit compat ioctl (optional) *
 *	int (*fb_compat_ioctl)(struct fb_info *info, unsigned int cmd,
 *			unsigned long arg);
 *
 *	* perform fb specific mmap *
 *	int (*fb_mmap)(struct fb_info *info, struct vm_area_struct *vma);
 *
 *	* save current hardware state *
 *	void (*fb_save_state)(struct fb_info *info);
 *
 *	* restore saved state *
 *	void (*fb_restore_state)(struct fb_info *info);
 * } ;
 */


/* ++roman: This structure abstracts from the underlying hardware (ST(e),
 * TT, or Falcon.
 *
 * int (*detect)(void)
 *   This function should detect the current video mode settings and
 *   store them in atafb_predefined[0] for later reference by the
 *   user. Return the index+1 of an equivalent predefined mode or 0
 *   if there is no such.
 *
 * int (*encode_fix)(struct fb_fix_screeninfo *fix,
 *                   struct atafb_par *par)
 *   This function should fill in the 'fix' structure based on the
 *   values in the 'par' structure.
 * !!! Obsolete, perhaps !!!
 *
 * int (*decode_var)(struct fb_var_screeninfo *var,
 *                   struct atafb_par *par)
 *   Get the video params out of 'var'. If a value doesn't fit, round
 *   it up, if it's too big, return EINVAL.
 *   Round up in the following order: bits_per_pixel, xres, yres,
 *   xres_virtual, yres_virtual, xoffset, yoffset, grayscale, bitfields,
 *   horizontal timing, vertical timing.
 *
 * int (*encode_var)(struct fb_var_screeninfo *var,
 *                   struct atafb_par *par);
 *   Fill the 'var' structure based on the values in 'par' and maybe
 *   other values read out of the hardware.
 *
 * void (*get_par)(struct atafb_par *par)
 *   Fill the hardware's 'par' structure.
 *   !!! Used only by detect() !!!
 *
 * void (*set_par)(struct atafb_par *par)
 *   Set the hardware according to 'par'.
 *
 * void (*set_screen_base)(void *s_base)
 *   Set the base address of the displayed frame buffer. Only called
 *   if yres_virtual > yres or xres_virtual > xres.
 *
 * int (*blank)(int blank_mode)
 *   Blank the screen if blank_mode != 0, else unblank. If blank == NULL then
 *   the caller blanks by setting the CLUT to all black. Return 0 if blanking
 *   succeeded, !=0 if un-/blanking failed due to e.g. a video mode which
 *   doesn't support it. Implements VESA suspend and powerdown modes on
 *   hardware that supports disabling hsync/vsync:
 *       blank_mode == 2: suspend vsync, 3:suspend hsync, 4: powerdown.
 */

static struct fb_hwswitch {
	int (*detect)(void);
	int (*encode_fix)(struct fb_fix_screeninfo *fix,
			  struct atafb_par *par);
	int (*decode_var)(struct fb_var_screeninfo *var,
			  struct atafb_par *par);
	int (*encode_var)(struct fb_var_screeninfo *var,
			  struct atafb_par *par);
	void (*get_par)(struct atafb_par *par);
	void (*set_par)(struct atafb_par *par);
	void (*set_screen_base)(void *s_base);
	int (*blank)(int blank_mode);
	int (*pan_display)(struct fb_var_screeninfo *var,
			   struct fb_info *info);
} *fbhw;

static char *autodetect_names[] = { "autodetect", NULL };
static char *stlow_names[] = { "stlow", NULL };
static char *stmid_names[] = { "stmid", "default5", NULL };
static char *sthigh_names[] = { "sthigh", "default4", NULL };
static char *ttlow_names[] = { "ttlow", NULL };
static char *ttmid_names[] = { "ttmid", "default1", NULL };
static char *tthigh_names[] = { "tthigh", "default2", NULL };
static char *vga2_names[] = { "vga2", NULL };
static char *vga4_names[] = { "vga4", NULL };
static char *vga16_names[] = { "vga16", "default3", NULL };
static char *vga256_names[] = { "vga256", NULL };
static char *falh2_names[] = { "falh2", NULL };
static char *falh16_names[] = { "falh16", NULL };

static char **fb_var_names[] = {
	autodetect_names,
	stlow_names,
	stmid_names,
	sthigh_names,
	ttlow_names,
	ttmid_names,
	tthigh_names,
	vga2_names,
	vga4_names,
	vga16_names,
	vga256_names,
	falh2_names,
	falh16_names,
	NULL
};

static struct fb_var_screeninfo atafb_predefined[] = {
	/*
	 * yres_virtual == 0 means use hw-scrolling if possible, else yres
	 */
	{ /* autodetect */
	  0, 0, 0, 0, 0, 0, 0, 0,		/* xres-grayscale */
	  {0, 0, 0}, {0, 0, 0}, {0, 0, 0}, {0, 0, 0},	/* red green blue tran*/
	  0, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ /* st low */
	  320, 200, 320, 0, 0, 0, 4, 0,
	  {0, 4, 0}, {0, 4, 0}, {0, 4, 0}, {0, 0, 0},
	  0, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ /* st mid */
	  640, 200, 640, 0, 0, 0, 2, 0,
	  {0, 4, 0}, {0, 4, 0}, {0, 4, 0}, {0, 0, 0},
	  0, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ /* st high */
	  640, 400, 640, 0, 0, 0, 1, 0,
	  {0, 4, 0}, {0, 4, 0}, {0, 4, 0}, {0, 0, 0},
	  0, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ /* tt low */
	  320, 480, 320, 0, 0, 0, 8, 0,
	  {0, 4, 0}, {0, 4, 0}, {0, 4, 0}, {0, 0, 0},
	  0, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ /* tt mid */
	  640, 480, 640, 0, 0, 0, 4, 0,
	  {0, 4, 0}, {0, 4, 0}, {0, 4, 0}, {0, 0, 0},
	  0, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ /* tt high */
	  1280, 960, 1280, 0, 0, 0, 1, 0,
	  {0, 4, 0}, {0, 4, 0}, {0, 4, 0}, {0, 0, 0},
	  0, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ /* vga2 */
	  640, 480, 640, 0, 0, 0, 1, 0,
	  {0, 6, 0}, {0, 6, 0}, {0, 6, 0}, {0, 0, 0},
	  0, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ /* vga4 */
	  640, 480, 640, 0, 0, 0, 2, 0,
	  {0, 4, 0}, {0, 4, 0}, {0, 4, 0}, {0, 0, 0},
	  0, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ /* vga16 */
	  640, 480, 640, 0, 0, 0, 4, 0,
	  {0, 6, 0}, {0, 6, 0}, {0, 6, 0}, {0, 0, 0},
	  0, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ /* vga256 */
	  640, 480, 640, 0, 0, 0, 8, 0,
	  {0, 6, 0}, {0, 6, 0}, {0, 6, 0}, {0, 0, 0},
	  0, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ /* falh2 */
	  896, 608, 896, 0, 0, 0, 1, 0,
	  {0, 6, 0}, {0, 6, 0}, {0, 6, 0}, {0, 0, 0},
	  0, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0 },
	{ /* falh16 */
	  896, 608, 896, 0, 0, 0, 4, 0,
	  {0, 6, 0}, {0, 6, 0}, {0, 6, 0}, {0, 0, 0},
	  0, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 0 },
};

static int num_atafb_predefined = ARRAY_SIZE(atafb_predefined);

static struct fb_videomode atafb_modedb[] __initdata = {
	/*
	 *  Atari Video Modes
	 *
	 *  If you change these, make sure to update DEFMODE_* as well!
	 */

	/*
	 *  ST/TT Video Modes
	 */

	{
		/* 320x200, 15 kHz, 60 Hz (ST low) */
		"st-low", 60, 320, 200, 32000, 32, 16, 31, 14, 96, 4,
		0, FB_VMODE_NONINTERLACED | FB_VMODE_YWRAP
	}, {
		/* 640x200, 15 kHz, 60 Hz (ST medium) */
		"st-mid", 60, 640, 200, 32000, 32, 16, 31, 14, 96, 4,
		0, FB_VMODE_NONINTERLACED | FB_VMODE_YWRAP
	}, {
		/* 640x400, 30.25 kHz, 63.5 Hz (ST high) */
		"st-high", 63, 640, 400, 32000, 128, 0, 40, 14, 128, 4,
		0, FB_VMODE_NONINTERLACED | FB_VMODE_YWRAP
	}, {
		/* 320x480, 15 kHz, 60 Hz (TT low) */
		"tt-low", 60, 320, 480, 31041, 120, 100, 8, 16, 140, 30,
		0, FB_VMODE_NONINTERLACED | FB_VMODE_YWRAP
	}, {
		/* 640x480, 29 kHz, 57 Hz (TT medium) */
		"tt-mid", 60, 640, 480, 31041, 120, 100, 8, 16, 140, 30,
		0, FB_VMODE_NONINTERLACED | FB_VMODE_YWRAP
	}, {
		/* 1280x960, 29 kHz, 60 Hz (TT high) */
		"tt-high", 57, 640, 960, 31041, 120, 100, 8, 16, 140, 30,
		0, FB_VMODE_NONINTERLACED | FB_VMODE_YWRAP
	},

	/*
	 *  VGA Video Modes
	 */

	{
		/* 640x480, 31 kHz, 60 Hz (VGA) */
		"vga", 63.5, 640, 480, 32000, 18, 42, 31, 11, 96, 3,
		0, FB_VMODE_NONINTERLACED | FB_VMODE_YWRAP
	}, {
		/* 640x400, 31 kHz, 70 Hz (VGA) */
		"vga70", 70, 640, 400, 32000, 18, 42, 31, 11, 96, 3,
		FB_SYNC_VERT_HIGH_ACT | FB_SYNC_COMP_HIGH_ACT, FB_VMODE_NONINTERLACED | FB_VMODE_YWRAP
	},

	/*
	 *  Falcon HiRes Video Modes
	 */

	{
		/* 896x608, 31 kHz, 60 Hz (Falcon High) */
		"falh", 60, 896, 608, 32000, 18, 42, 31, 1, 96,3,
		0, FB_VMODE_NONINTERLACED | FB_VMODE_YWRAP
	},
};

#define NUM_TOTAL_MODES  ARRAY_SIZE(atafb_modedb)

static char *mode_option __initdata = NULL;

 /* default modes */

#define DEFMODE_TT	5		/* "tt-high" for TT */
#define DEFMODE_F30	7		/* "vga70" for Falcon */
#define DEFMODE_STE	2		/* "st-high" for ST/E */
#define DEFMODE_EXT	6		/* "vga" for external */


static int get_video_mode(char *vname)
{
	char ***name_list;
	char **name;
	int i;

	name_list = fb_var_names;
	for (i = 0; i < num_atafb_predefined; i++) {
		name = *name_list++;
		if (!name || !*name)
			break;
		while (*name) {
			if (!strcmp(vname, *name))
				return i + 1;
			name++;
		}
	}
	return 0;
}



/* ------------------- TT specific functions ---------------------- */

#ifdef ATAFB_TT

static int tt_encode_fix(struct fb_fix_screeninfo *fix, struct atafb_par *par)
{
	int mode;

	strcpy(fix->id, "Atari Builtin");
	fix->smem_start = (unsigned long)real_screen_base;
	fix->smem_len = screen_len;
	fix->type = FB_TYPE_INTERLEAVED_PLANES;
	fix->type_aux = 2;
	fix->visual = FB_VISUAL_PSEUDOCOLOR;
	mode = par->hw.tt.mode & TT_SHIFTER_MODEMASK;
	if (mode == TT_SHIFTER_TTHIGH || mode == TT_SHIFTER_STHIGH) {
		fix->type = FB_TYPE_PACKED_PIXELS;
		fix->type_aux = 0;
		if (mode == TT_SHIFTER_TTHIGH)
			fix->visual = FB_VISUAL_MONO01;
	}
	fix->xpanstep = 0;
	fix->ypanstep = 1;
	fix->ywrapstep = 0;
	fix->line_length = 0;
	fix->accel = FB_ACCEL_ATARIBLITT;
	return 0;
}

static int tt_decode_var(struct fb_var_screeninfo *var, struct atafb_par *par)
{
	int xres = var->xres;
	int yres = var->yres;
	int bpp = var->bits_per_pixel;
	int linelen;
	int yres_virtual = var->yres_virtual;

	if (mono_moni) {
		if (bpp > 1 || xres > sttt_xres * 2 || yres > tt_yres * 2)
			return -EINVAL;
		par->hw.tt.mode = TT_SHIFTER_TTHIGH;
		xres = sttt_xres * 2;
		yres = tt_yres * 2;
		bpp = 1;
	} else {
		if (bpp > 8 || xres > sttt_xres || yres > tt_yres)
			return -EINVAL;
		if (bpp > 4) {
			if (xres > sttt_xres / 2 || yres > tt_yres)
				return -EINVAL;
			par->hw.tt.mode = TT_SHIFTER_TTLOW;
			xres = sttt_xres / 2;
			yres = tt_yres;
			bpp = 8;
		} else if (bpp > 2) {
			if (xres > sttt_xres || yres > tt_yres)
				return -EINVAL;
			if (xres > sttt_xres / 2 || yres > st_yres / 2) {
				par->hw.tt.mode = TT_SHIFTER_TTMID;
				xres = sttt_xres;
				yres = tt_yres;
				bpp = 4;
			} else {
				par->hw.tt.mode = TT_SHIFTER_STLOW;
				xres = sttt_xres / 2;
				yres = st_yres / 2;
				bpp = 4;
			}
		} else if (bpp > 1) {
			if (xres > sttt_xres || yres > st_yres / 2)
				return -EINVAL;
			par->hw.tt.mode = TT_SHIFTER_STMID;
			xres = sttt_xres;
			yres = st_yres / 2;
			bpp = 2;
		} else if (var->xres > sttt_xres || var->yres > st_yres) {
			return -EINVAL;
		} else {
			par->hw.tt.mode = TT_SHIFTER_STHIGH;
			xres = sttt_xres;
			yres = st_yres;
			bpp = 1;
		}
	}
	if (yres_virtual <= 0)
		yres_virtual = 0;
	else if (yres_virtual < yres)
		yres_virtual = yres;
	if (var->sync & FB_SYNC_EXT)
		par->hw.tt.sync = 0;
	else
		par->hw.tt.sync = 1;
	linelen = xres * bpp / 8;
	if (yres_virtual * linelen > screen_len && screen_len)
		return -EINVAL;
	if (yres * linelen > screen_len && screen_len)
		return -EINVAL;
	if (var->yoffset + yres > yres_virtual && yres_virtual)
		return -EINVAL;
	par->yres_virtual = yres_virtual;
	par->screen_base = screen_base + var->yoffset * linelen;
	return 0;
}

static int tt_encode_var(struct fb_var_screeninfo *var, struct atafb_par *par)
{
	int linelen;
	memset(var, 0, sizeof(struct fb_var_screeninfo));
	var->red.offset = 0;
	var->red.length = 4;
	var->red.msb_right = 0;
	var->grayscale = 0;

	var->pixclock = 31041;
	var->left_margin = 120;		/* these may be incorrect */
	var->right_margin = 100;
	var->upper_margin = 8;
	var->lower_margin = 16;
	var->hsync_len = 140;
	var->vsync_len = 30;

	var->height = -1;
	var->width = -1;

	if (par->hw.tt.sync & 1)
		var->sync = 0;
	else
		var->sync = FB_SYNC_EXT;

	switch (par->hw.tt.mode & TT_SHIFTER_MODEMASK) {
	case TT_SHIFTER_STLOW:
		var->xres = sttt_xres / 2;
		var->xres_virtual = sttt_xres_virtual / 2;
		var->yres = st_yres / 2;
		var->bits_per_pixel = 4;
		break;
	case TT_SHIFTER_STMID:
		var->xres = sttt_xres;
		var->xres_virtual = sttt_xres_virtual;
		var->yres = st_yres / 2;
		var->bits_per_pixel = 2;
		break;
	case TT_SHIFTER_STHIGH:
		var->xres = sttt_xres;
		var->xres_virtual = sttt_xres_virtual;
		var->yres = st_yres;
		var->bits_per_pixel = 1;
		break;
	case TT_SHIFTER_TTLOW:
		var->xres = sttt_xres / 2;
		var->xres_virtual = sttt_xres_virtual / 2;
		var->yres = tt_yres;
		var->bits_per_pixel = 8;
		break;
	case TT_SHIFTER_TTMID:
		var->xres = sttt_xres;
		var->xres_virtual = sttt_xres_virtual;
		var->yres = tt_yres;
		var->bits_per_pixel = 4;
		break;
	case TT_SHIFTER_TTHIGH:
		var->red.length = 0;
		var->xres = sttt_xres * 2;
		var->xres_virtual = sttt_xres_virtual * 2;
		var->yres = tt_yres * 2;
		var->bits_per_pixel = 1;
		break;
	}
	var->blue = var->green = var->red;
	var->transp.offset = 0;
	var->transp.length = 0;
	var->transp.msb_right = 0;
	linelen = var->xres_virtual * var->bits_per_pixel / 8;
	if (!use_hwscroll)
		var->yres_virtual = var->yres;
	else if (screen_len) {
		if (par->yres_virtual)
			var->yres_virtual = par->yres_virtual;
		else
			/* yres_virtual == 0 means use maximum */
			var->yres_virtual = screen_len / linelen;
	} else {
		if (hwscroll < 0)
			var->yres_virtual = 2 * var->yres;
		else
			var->yres_virtual = var->yres + hwscroll * 16;
	}
	var->xoffset = 0;
	if (screen_base)
		var->yoffset = (par->screen_base - screen_base) / linelen;
	else
		var->yoffset = 0;
	var->nonstd = 0;
	var->activate = 0;
	var->vmode = FB_VMODE_NONINTERLACED;
	return 0;
}

static void tt_get_par(struct atafb_par *par)
{
	unsigned long addr;
	par->hw.tt.mode = shifter_tt.tt_shiftmode;
	par->hw.tt.sync = shifter.syncmode;
	addr = ((shifter.bas_hi & 0xff) << 16) |
	       ((shifter.bas_md & 0xff) << 8)  |
	       ((shifter.bas_lo & 0xff));
	par->screen_base = phys_to_virt(addr);
}

static void tt_set_par(struct atafb_par *par)
{
	shifter_tt.tt_shiftmode = par->hw.tt.mode;
	shifter.syncmode = par->hw.tt.sync;
	/* only set screen_base if really necessary */
	if (current_par.screen_base != par->screen_base)
		fbhw->set_screen_base(par->screen_base);
}

static int tt_setcolreg(unsigned int regno, unsigned int red,
			unsigned int green, unsigned int blue,
			unsigned int transp, struct fb_info *info)
{
	if ((shifter_tt.tt_shiftmode & TT_SHIFTER_MODEMASK) == TT_SHIFTER_STHIGH)
		regno += 254;
	if (regno > 255)
		return 1;
	tt_palette[regno] = (((red >> 12) << 8) | ((green >> 12) << 4) |
			     (blue >> 12));
	if ((shifter_tt.tt_shiftmode & TT_SHIFTER_MODEMASK) ==
	    TT_SHIFTER_STHIGH && regno == 254)
		tt_palette[0] = 0;
	return 0;
}

static int tt_detect(void)
{
	struct atafb_par par;

	/* Determine the connected monitor: The DMA sound must be
	 * disabled before reading the MFP GPIP, because the Sound
	 * Done Signal and the Monochrome Detect are XORed together!
	 *
	 * Even on a TT, we should look if there is a DMA sound. It was
	 * announced that the Eagle is TT compatible, but only the PCM is
	 * missing...
	 */
	if (ATARIHW_PRESENT(PCM_8BIT)) {
		tt_dmasnd.ctrl = DMASND_CTRL_OFF;
		udelay(20);		/* wait a while for things to settle down */
	}
	mono_moni = (mfp.par_dt_reg & 0x80) == 0;

	tt_get_par(&par);
	tt_encode_var(&atafb_predefined[0], &par);

	return 1;
}

#endif /* ATAFB_TT */

/* ------------------- Falcon specific functions ---------------------- */

#ifdef ATAFB_FALCON

static int mon_type;		/* Falcon connected monitor */
static int f030_bus_width;	/* Falcon ram bus width (for vid_control) */
#define F_MON_SM	0
#define F_MON_SC	1
#define F_MON_VGA	2
#define F_MON_TV	3

static struct pixel_clock {
	unsigned long f;	/* f/[Hz] */
	unsigned long t;	/* t/[ps] (=1/f) */
	int right, hsync, left;	/* standard timing in clock cycles, not pixel */
	/* hsync initialized in falcon_detect() */
	int sync_mask;		/* or-mask for hw.falcon.sync to set this clock */
	int control_mask;	/* ditto, for hw.falcon.vid_control */
} f25 = {
	25175000, 39721, 18, 0, 42, 0x0, VCO_CLOCK25
}, f32 = {
	32000000, 31250, 18, 0, 42, 0x0, 0
}, fext = {
	0, 0, 18, 0, 42, 0x1, 0
};

/* VIDEL-prescale values [mon_type][pixel_length from VCO] */
static int vdl_prescale[4][3] = {
	{ 4,2,1 }, { 4,2,1 }, { 4,2,2 }, { 4,2,1 }
};

/* Default hsync timing [mon_type] in picoseconds */
static long h_syncs[4] = { 3000000, 4875000, 4000000, 4875000 };

#ifdef FBCON_HAS_CFB16
static u16 fbcon_cfb16_cmap[16];
#endif

static inline int hxx_prescale(struct falcon_hw *hw)
{
	return hw->ste_mode ? 16
			    : vdl_prescale[mon_type][hw->vid_mode >> 2 & 0x3];
}

static int falcon_encode_fix(struct fb_fix_screeninfo *fix,
			     struct atafb_par *par)
{
	strcpy(fix->id, "Atari Builtin");
	fix->smem_start = (unsigned long)real_screen_base;
	fix->smem_len = screen_len;
	fix->type = FB_TYPE_INTERLEAVED_PLANES;
	fix->type_aux = 2;
	fix->visual = FB_VISUAL_PSEUDOCOLOR;
	fix->xpanstep = 1;
	fix->ypanstep = 1;
	fix->ywrapstep = 0;
	if (par->hw.falcon.mono) {
		fix->type = FB_TYPE_PACKED_PIXELS;
		fix->type_aux = 0;
		/* no smooth scrolling with longword aligned video mem */
		fix->xpanstep = 32;
	} else if (par->hw.falcon.f_shift & 0x100) {
		fix->type = FB_TYPE_PACKED_PIXELS;
		fix->type_aux = 0;
		/* Is this ok or should it be DIRECTCOLOR? */
		fix->visual = FB_VISUAL_TRUECOLOR;
		fix->xpanstep = 2;
	}
	fix->line_length = 0;
	fix->accel = FB_ACCEL_ATARIBLITT;
	return 0;
}

static int falcon_decode_var(struct fb_var_screeninfo *var,
			     struct atafb_par *par)
{
	int bpp = var->bits_per_pixel;
	int xres = var->xres;
	int yres = var->yres;
	int xres_virtual = var->xres_virtual;
	int yres_virtual = var->yres_virtual;
	int left_margin, right_margin, hsync_len;
	int upper_margin, lower_margin, vsync_len;
	int linelen;
	int interlace = 0, doubleline = 0;
	struct pixel_clock *pclock;
	int plen;			/* width of pixel in clock cycles */
	int xstretch;
	int prescale;
	int longoffset = 0;
	int hfreq, vfreq;
	int hdb_off, hde_off, base_off;
	int gstart, gend1, gend2, align;

/*
	Get the video params out of 'var'. If a value doesn't fit, round
	it up, if it's too big, return EINVAL.
	Round up in the following order: bits_per_pixel, xres, yres,
	xres_virtual, yres_virtual, xoffset, yoffset, grayscale, bitfields,
	horizontal timing, vertical timing.

	There is a maximum of screen resolution determined by pixelclock
	and minimum frame rate -- (X+hmarg.)*(Y+vmarg.)*vfmin <= pixelclock.
	In interlace mode this is     "     *    "     *vfmin <= pixelclock.
	Additional constraints: hfreq.
	Frequency range for multisync monitors is given via command line.
	For TV and SM124 both frequencies are fixed.

	X % 16 == 0 to fit 8x?? font (except 1 bitplane modes must use X%32 == 0)
	Y % 16 == 0 to fit 8x16 font
	Y % 8 == 0 if Y<400

	Currently interlace and doubleline mode in var are ignored.
	On SM124 and TV only the standard resolutions can be used.
*/

	/* Reject uninitialized mode */
	if (!xres || !yres || !bpp)
		return -EINVAL;

	if (mon_type == F_MON_SM && bpp != 1)
		return -EINVAL;

	if (bpp <= 1) {
		bpp = 1;
		par->hw.falcon.f_shift = 0x400;
		par->hw.falcon.st_shift = 0x200;
	} else if (bpp <= 2) {
		bpp = 2;
		par->hw.falcon.f_shift = 0x000;
		par->hw.falcon.st_shift = 0x100;
	} else if (bpp <= 4) {
		bpp = 4;
		par->hw.falcon.f_shift = 0x000;
		par->hw.falcon.st_shift = 0x000;
	} else if (bpp <= 8) {
		bpp = 8;
		par->hw.falcon.f_shift = 0x010;
	} else if (bpp <= 16) {
		bpp = 16;		/* packed pixel mode */
		par->hw.falcon.f_shift = 0x100;	/* hicolor, no overlay */
	} else
		return -EINVAL;
	par->hw.falcon.bpp = bpp;

	if (mon_type == F_MON_SM || DontCalcRes) {
		/* Skip all calculations. VGA/TV/SC1224 only supported. */
		struct fb_var_screeninfo *myvar = &atafb_predefined[0];

		if (bpp > myvar->bits_per_pixel ||
		    var->xres > myvar->xres ||
		    var->yres > myvar->yres)
			return -EINVAL;
		fbhw->get_par(par);	/* Current par will be new par */
		goto set_screen_base;	/* Don't forget this */
	}

	/* Only some fixed resolutions < 640x400 */
	if (xres <= 320)
		xres = 320;
	else if (xres <= 640 && bpp != 16)
		xres = 640;
	if (yres <= 200)
		yres = 200;
	else if (yres <= 240)
		yres = 240;
	else if (yres <= 400)
		yres = 400;

	/* 2 planes must use STE compatibility mode */
	par->hw.falcon.ste_mode = bpp == 2;
	par->hw.falcon.mono = bpp == 1;

	/* Total and visible scanline length must be a multiple of one longword,
	 * this and the console fontwidth yields the alignment for xres and
	 * xres_virtual.
	 * TODO: this way "odd" fontheights are not supported
	 *
	 * Special case in STE mode: blank and graphic positions don't align,
	 * avoid trash at right margin
	 */
	if (par->hw.falcon.ste_mode)
		xres = (xres + 63) & ~63;
	else if (bpp == 1)
		xres = (xres + 31) & ~31;
	else
		xres = (xres + 15) & ~15;
	if (yres >= 400)
		yres = (yres + 15) & ~15;
	else
		yres = (yres + 7) & ~7;

	if (xres_virtual < xres)
		xres_virtual = xres;
	else if (bpp == 1)
		xres_virtual = (xres_virtual + 31) & ~31;
	else
		xres_virtual = (xres_virtual + 15) & ~15;

	if (yres_virtual <= 0)
		yres_virtual = 0;
	else if (yres_virtual < yres)
		yres_virtual = yres;

	/* backward bug-compatibility */
	if (var->pixclock > 1)
		var->pixclock -= 1;

	par->hw.falcon.line_width = bpp * xres / 16;
	par->hw.falcon.line_offset = bpp * (xres_virtual - xres) / 16;

	/* single or double pixel width */
	xstretch = (xres < 640) ? 2 : 1;

#if 0 /* SM124 supports only 640x400, this is rejected above */
	if (mon_type == F_MON_SM) {
		if (xres != 640 && yres != 400)
			return -EINVAL;
		plen = 1;
		pclock = &f32;
		/* SM124-mode is special */
		par->hw.falcon.ste_mode = 1;
		par->hw.falcon.f_shift = 0x000;
		par->hw.falcon.st_shift = 0x200;
		left_margin = hsync_len = 128 / plen;
		right_margin = 0;
		/* TODO set all margins */
	} else
#endif
	if (mon_type == F_MON_SC || mon_type == F_MON_TV) {
		plen = 2 * xstretch;
		if (var->pixclock > f32.t * plen)
			return -EINVAL;
		pclock = &f32;
		if (yres > 240)
			interlace = 1;
		if (var->pixclock == 0) {
			/* set some minimal margins which center the screen */
			left_margin = 32;
			right_margin = 18;
			hsync_len = pclock->hsync / plen;
			upper_margin = 31;
			lower_margin = 14;
			vsync_len = interlace ? 3 : 4;
		} else {
			left_margin = var->left_margin;
			right_margin = var->right_margin;
			hsync_len = var->hsync_len;
			upper_margin = var->upper_margin;
			lower_margin = var->lower_margin;
			vsync_len = var->vsync_len;
			if (var->vmode & FB_VMODE_INTERLACED) {
				upper_margin = (upper_margin + 1) / 2;
				lower_margin = (lower_margin + 1) / 2;
				vsync_len = (vsync_len + 1) / 2;
			} else if (var->vmode & FB_VMODE_DOUBLE) {
				upper_margin *= 2;
				lower_margin *= 2;
				vsync_len *= 2;
			}
		}
	} else {			/* F_MON_VGA */
		if (bpp == 16)
			xstretch = 2;	/* Double pixel width only for hicolor */
		/* Default values are used for vert./hor. timing if no pixelclock given. */
		if (var->pixclock == 0) {
			int linesize;

			/* Choose master pixelclock depending on hor. timing */
			plen = 1 * xstretch;
			if ((plen * xres + f25.right + f25.hsync + f25.left) *
			    fb_info.monspecs.hfmin < f25.f)
				pclock = &f25;
			else if ((plen * xres + f32.right + f32.hsync +
				  f32.left) * fb_info.monspecs.hfmin < f32.f)
				pclock = &f32;
			else if ((plen * xres + fext.right + fext.hsync +
				  fext.left) * fb_info.monspecs.hfmin < fext.f &&
			         fext.f)
				pclock = &fext;
			else
				return -EINVAL;

			left_margin = pclock->left / plen;
			right_margin = pclock->right / plen;
			hsync_len = pclock->hsync / plen;
			linesize = left_margin + xres + right_margin + hsync_len;
			upper_margin = 31;
			lower_margin = 11;
			vsync_len = 3;
		} else {
			/* Choose largest pixelclock <= wanted clock */
			int i;
			unsigned long pcl = ULONG_MAX;
			pclock = 0;
			for (i = 1; i <= 4; i *= 2) {
				if (f25.t * i >= var->pixclock &&
				    f25.t * i < pcl) {
					pcl = f25.t * i;
					pclock = &f25;
				}
				if (f32.t * i >= var->pixclock &&
				    f32.t * i < pcl) {
					pcl = f32.t * i;
					pclock = &f32;
				}
				if (fext.t && fext.t * i >= var->pixclock &&
				    fext.t * i < pcl) {
					pcl = fext.t * i;
					pclock = &fext;
				}
			}
			if (!pclock)
				return -EINVAL;
			plen = pcl / pclock->t;

			left_margin = var->left_margin;
			right_margin = var->right_margin;
			hsync_len = var->hsync_len;
			upper_margin = var->upper_margin;
			lower_margin = var->lower_margin;
			vsync_len = var->vsync_len;
			/* Internal unit is [single lines per (half-)frame] */
			if (var->vmode & FB_VMODE_INTERLACED) {
				/* # lines in half frame */
				/* External unit is [lines per full frame] */
				upper_margin = (upper_margin + 1) / 2;
				lower_margin = (lower_margin + 1) / 2;
				vsync_len = (vsync_len + 1) / 2;
			} else if (var->vmode & FB_VMODE_DOUBLE) {
				/* External unit is [double lines per frame] */
				upper_margin *= 2;
				lower_margin *= 2;
				vsync_len *= 2;
			}
		}
		if (pclock == &fext)
			longoffset = 1;	/* VIDEL doesn't synchronize on short offset */
	}
	/* Is video bus bandwidth (32MB/s) too low for this resolution? */
	/* this is definitely wrong if bus clock != 32MHz */
	if (pclock->f / plen / 8 * bpp > 32000000L)
		return -EINVAL;

	if (vsync_len < 1)
		vsync_len = 1;

	/* include sync lengths in right/lower margin for all calculations */
	right_margin += hsync_len;
	lower_margin += vsync_len;

	/* ! In all calculations of margins we use # of lines in half frame
	 * (which is a full frame in non-interlace mode), so we can switch
	 * between interlace and non-interlace without messing around
	 * with these.
	 */
again:
	/* Set base_offset 128 and video bus width */
	par->hw.falcon.vid_control = mon_type | f030_bus_width;
	if (!longoffset)
		par->hw.falcon.vid_control |= VCO_SHORTOFFS;	/* base_offset 64 */
	if (var->sync & FB_SYNC_HOR_HIGH_ACT)
		par->hw.falcon.vid_control |= VCO_HSYPOS;
	if (var->sync & FB_SYNC_VERT_HIGH_ACT)
		par->hw.falcon.vid_control |= VCO_VSYPOS;
	/* Pixelclock */
	par->hw.falcon.vid_control |= pclock->control_mask;
	/* External or internal clock */
	par->hw.falcon.sync = pclock->sync_mask | 0x2;
	/* Pixellength and prescale */
	par->hw.falcon.vid_mode = (2 / plen) << 2;
	if (doubleline)
		par->hw.falcon.vid_mode |= VMO_DOUBLE;
	if (interlace)
		par->hw.falcon.vid_mode |= VMO_INTER;

	/*********************
	 * Horizontal timing: unit = [master clock cycles]
	 * unit of hxx-registers: [master clock cycles * prescale]
	 * Hxx-registers are 9 bit wide
	 *
	 * 1 line = ((hht + 2) * 2 * prescale) clock cycles
	 *
	 * graphic output = hdb & 0x200 ?
	 *        ((hht + 2) * 2 - hdb + hde) * prescale - hdboff + hdeoff:
	 *        (hht + 2  - hdb + hde) * prescale - hdboff + hdeoff
	 * (this must be a multiple of plen*128/bpp, on VGA pixels
	 *  to the right may be cut off with a bigger right margin)
	 *
	 * start of graphics relative to start of 1st halfline = hdb & 0x200 ?
	 *        (hdb - hht - 2) * prescale + hdboff :
	 *        hdb * prescale + hdboff
	 *
	 * end of graphics relative to start of 1st halfline =
	 *        (hde + hht + 2) * prescale + hdeoff
	 *********************/
	/* Calculate VIDEL registers */
{
	prescale = hxx_prescale(&par->hw.falcon);
	base_off = par->hw.falcon.vid_control & VCO_SHORTOFFS ? 64 : 128;

	/* Offsets depend on video mode */
	/* Offsets are in clock cycles, divide by prescale to
	 * calculate hd[be]-registers
	 */
	if (par->hw.falcon.f_shift & 0x100) {
		align = 1;
		hde_off = 0;
		hdb_off = (base_off + 16 * plen) + prescale;
	} else {
		align = 128 / bpp;
		hde_off = ((128 / bpp + 2) * plen);
		if (par->hw.falcon.ste_mode)
			hdb_off = (64 + base_off + (128 / bpp + 2) * plen) + prescale;
		else
			hdb_off = (base_off + (128 / bpp + 18) * plen) + prescale;
	}

	gstart = (prescale / 2 + plen * left_margin) / prescale;
	/* gend1 is for hde (gend-gstart multiple of align), shifter's xres */
	gend1 = gstart + ((xres + align - 1) / align) * align * plen / prescale;
	/* gend2 is for hbb, visible xres (rest to gend1 is cut off by hblank) */
	gend2 = gstart + xres * plen / prescale;
	par->HHT = plen * (left_margin + xres + right_margin) /
			   (2 * prescale) - 2;
/*	par->HHT = (gend2 + plen * right_margin / prescale) / 2 - 2;*/

	par->HDB = gstart - hdb_off / prescale;
	par->HBE = gstart;
	if (par->HDB < 0)
		par->HDB += par->HHT + 2 + 0x200;
	par->HDE = gend1 - par->HHT - 2 - hde_off / prescale;
	par->HBB = gend2 - par->HHT - 2;
#if 0
	/* One more Videl constraint: data fetch of two lines must not overlap */
	if ((par->HDB & 0x200) && (par->HDB & ~0x200) - par->HDE <= 5) {
		/* if this happens increase margins, decrease hfreq. */
	}
#endif
	if (hde_off % prescale)
		par->HBB++;		/* compensate for non matching hde and hbb */
	par->HSS = par->HHT + 2 - plen * hsync_len / prescale;
	if (par->HSS < par->HBB)
		par->HSS = par->HBB;
}

	/*  check hor. frequency */
	hfreq = pclock->f / ((par->HHT + 2) * prescale * 2);
	if (hfreq > fb_info.monspecs.hfmax && mon_type != F_MON_VGA) {
		/* ++guenther:   ^^^^^^^^^^^^^^^^^^^ can't remember why I did this */
		/* Too high -> enlarge margin */
		left_margin += 1;
		right_margin += 1;
		goto again;
	}
	if (hfreq > fb_info.monspecs.hfmax || hfreq < fb_info.monspecs.hfmin)
		return -EINVAL;

	/* Vxx-registers */
	/* All Vxx must be odd in non-interlace, since frame starts in the middle
	 * of the first displayed line!
	 * One frame consists of VFT+1 half lines. VFT+1 must be even in
	 * non-interlace, odd in interlace mode for synchronisation.
	 * Vxx-registers are 11 bit wide
	 */
	par->VBE = (upper_margin * 2 + 1); /* must begin on odd halfline */
	par->VDB = par->VBE;
	par->VDE = yres;
	if (!interlace)
		par->VDE <<= 1;
	if (doubleline)
		par->VDE <<= 1;		/* VDE now half lines per (half-)frame */
	par->VDE += par->VDB;
	par->VBB = par->VDE;
	par->VFT = par->VBB + (lower_margin * 2 - 1) - 1;
	par->VSS = par->VFT + 1 - (vsync_len * 2 - 1);
	/* vbb,vss,vft must be even in interlace mode */
	if (interlace) {
		par->VBB++;
		par->VSS++;
		par->VFT++;
	}

	/* V-frequency check, hope I didn't create any loop here. */
	/* Interlace and doubleline are mutually exclusive. */
	vfreq = (hfreq * 2) / (par->VFT + 1);
	if (vfreq > fb_info.monspecs.vfmax && !doubleline && !interlace) {
		/* Too high -> try again with doubleline */
		doubleline = 1;
		goto again;
	} else if (vfreq < fb_info.monspecs.vfmin && !interlace && !doubleline) {
		/* Too low -> try again with interlace */
		interlace = 1;
		goto again;
	} else if (vfreq < fb_info.monspecs.vfmin && doubleline) {
		/* Doubleline too low -> clear doubleline and enlarge margins */
		int lines;
		doubleline = 0;
		for (lines = 0;
		     (hfreq * 2) / (par->VFT + 1 + 4 * lines - 2 * yres) >
		     fb_info.monspecs.vfmax;
		     lines++)
			;
		upper_margin += lines;
		lower_margin += lines;
		goto again;
	} else if (vfreq > fb_info.monspecs.vfmax && doubleline) {
		/* Doubleline too high -> enlarge margins */
		int lines;
		for (lines = 0;
		     (hfreq * 2) / (par->VFT + 1 + 4 * lines) >
		     fb_info.monspecs.vfmax;
		     lines += 2)
			;
		upper_margin += lines;
		lower_margin += lines;
		goto again;
	} else if (vfreq > fb_info.monspecs.vfmax && interlace) {
		/* Interlace, too high -> enlarge margins */
		int lines;
		for (lines = 0;
		     (hfreq * 2) / (par->VFT + 1 + 4 * lines) >
		     fb_info.monspecs.vfmax;
		     lines++)
			;
		upper_margin += lines;
		lower_margin += lines;
		goto again;
	} else if (vfreq < fb_info.monspecs.vfmin ||
		   vfreq > fb_info.monspecs.vfmax)
		return -EINVAL;

set_screen_base:
	linelen = xres_virtual * bpp / 8;
	if (yres_virtual * linelen > screen_len && screen_len)
		return -EINVAL;
	if (yres * linelen > screen_len && screen_len)
		return -EINVAL;
	if (var->yoffset + yres > yres_virtual && yres_virtual)
		return -EINVAL;
	par->yres_virtual = yres_virtual;
	par->screen_base = screen_base + var->yoffset * linelen;
	par->hw.falcon.xoffset = 0;

	// FIXME!!! sort of works, no crash
	//par->next_line = linelen;
	//par->next_plane = yres_virtual * linelen;
	par->next_line = linelen;
	par->next_plane = 2;
	// crashes
	//par->next_plane = linelen;
	//par->next_line  = yres_virtual * linelen;

	return 0;
}

static int falcon_encode_var(struct fb_var_screeninfo *var,
			     struct atafb_par *par)
{
/* !!! only for VGA !!! */
	int linelen;
	int prescale, plen;
	int hdb_off, hde_off, base_off;
	struct falcon_hw *hw = &par->hw.falcon;

	memset(var, 0, sizeof(struct fb_var_screeninfo));
	/* possible frequencies: 25.175 or 32MHz */
	var->pixclock = hw->sync & 0x1 ? fext.t :
	                hw->vid_control & VCO_CLOCK25 ? f25.t : f32.t;

	var->height = -1;
	var->width = -1;

	var->sync = 0;
	if (hw->vid_control & VCO_HSYPOS)
		var->sync |= FB_SYNC_HOR_HIGH_ACT;
	if (hw->vid_control & VCO_VSYPOS)
		var->sync |= FB_SYNC_VERT_HIGH_ACT;

	var->vmode = FB_VMODE_NONINTERLACED;
	if (hw->vid_mode & VMO_INTER)
		var->vmode |= FB_VMODE_INTERLACED;
	if (hw->vid_mode & VMO_DOUBLE)
		var->vmode |= FB_VMODE_DOUBLE;

	/* visible y resolution:
	 * Graphics display starts at line VDB and ends at line
	 * VDE. If interlace mode off unit of VC-registers is
	 * half lines, else lines.
	 */
	var->yres = hw->vde - hw->vdb;
	if (!(var->vmode & FB_VMODE_INTERLACED))
		var->yres >>= 1;
	if (var->vmode & FB_VMODE_DOUBLE)
		var->yres >>= 1;

	/*
	 * to get bpp, we must examine f_shift and st_shift.
	 * f_shift is valid if any of bits no. 10, 8 or 4
	 * is set. Priority in f_shift is: 10 ">" 8 ">" 4, i.e.
	 * if bit 10 set then bit 8 and bit 4 don't care...
	 * If all these bits are 0 get display depth from st_shift
	 * (as for ST and STE)
	 */
	if (hw->f_shift & 0x400)	/* 2 colors */
		var->bits_per_pixel = 1;
	else if (hw->f_shift & 0x100)	/* hicolor */
		var->bits_per_pixel = 16;
	else if (hw->f_shift & 0x010)	/* 8 bitplanes */
		var->bits_per_pixel = 8;
	else if (hw->st_shift == 0)
		var->bits_per_pixel = 4;
	else if (hw->st_shift == 0x100)
		var->bits_per_pixel = 2;
	else				/* if (hw->st_shift == 0x200) */
		var->bits_per_pixel = 1;

	var->xres = hw->line_width * 16 / var->bits_per_pixel;
	var->xres_virtual = var->xres + hw->line_offset * 16 / var->bits_per_pixel;
	if (hw->xoffset)
		var->xres_virtual += 16;

	if (var->bits_per_pixel == 16) {
		var->red.offset = 11;
		var->red.length = 5;
		var->red.msb_right = 0;
		var->green.offset = 5;
		var->green.length = 6;
		var->green.msb_right = 0;
		var->blue.offset = 0;
		var->blue.length = 5;
		var->blue.msb_right = 0;
	} else {
		var->red.offset = 0;
		var->red.length = hw->ste_mode ? 4 : 6;
		if (var->red.length > var->bits_per_pixel)
			var->red.length = var->bits_per_pixel;
		var->red.msb_right = 0;
		var->grayscale = 0;
		var->blue = var->green = var->red;
	}
	var->transp.offset = 0;
	var->transp.length = 0;
	var->transp.msb_right = 0;

	linelen = var->xres_virtual * var->bits_per_pixel / 8;
	if (screen_len) {
		if (par->yres_virtual)
			var->yres_virtual = par->yres_virtual;
		else
			/* yres_virtual == 0 means use maximum */
			var->yres_virtual = screen_len / linelen;
	} else {
		if (hwscroll < 0)
			var->yres_virtual = 2 * var->yres;
		else
			var->yres_virtual = var->yres + hwscroll * 16;
	}
	var->xoffset = 0;		/* TODO change this */

	/* hdX-offsets */
	prescale = hxx_prescale(hw);
	plen = 4 >> (hw->vid_mode >> 2 & 0x3);
	base_off = hw->vid_control & VCO_SHORTOFFS ? 64 : 128;
	if (hw->f_shift & 0x100) {
		hde_off = 0;
		hdb_off = (base_off + 16 * plen) + prescale;
	} else {
		hde_off = ((128 / var->bits_per_pixel + 2) * plen);
		if (hw->ste_mode)
			hdb_off = (64 + base_off + (128 / var->bits_per_pixel + 2) * plen)
					 + prescale;
		else
			hdb_off = (base_off + (128 / var->bits_per_pixel + 18) * plen)
					 + prescale;
	}

	/* Right margin includes hsync */
	var->left_margin = hdb_off + prescale * ((hw->hdb & 0x1ff) -
					   (hw->hdb & 0x200 ? 2 + hw->hht : 0));
	if (hw->ste_mode || mon_type != F_MON_VGA)
		var->right_margin = prescale * (hw->hht + 2 - hw->hde) - hde_off;
	else
		/* can't use this in ste_mode, because hbb is +1 off */
		var->right_margin = prescale * (hw->hht + 2 - hw->hbb);
	var->hsync_len = prescale * (hw->hht + 2 - hw->hss);

	/* Lower margin includes vsync */
	var->upper_margin = hw->vdb / 2;	/* round down to full lines */
	var->lower_margin = (hw->vft + 1 - hw->vde + 1) / 2;	/* round up */
	var->vsync_len = (hw->vft + 1 - hw->vss + 1) / 2;	/* round up */
	if (var->vmode & FB_VMODE_INTERLACED) {
		var->upper_margin *= 2;
		var->lower_margin *= 2;
		var->vsync_len *= 2;
	} else if (var->vmode & FB_VMODE_DOUBLE) {
		var->upper_margin = (var->upper_margin + 1) / 2;
		var->lower_margin = (var->lower_margin + 1) / 2;
		var->vsync_len = (var->vsync_len + 1) / 2;
	}

	var->pixclock *= plen;
	var->left_margin /= plen;
	var->right_margin /= plen;
	var->hsync_len /= plen;

	var->right_margin -= var->hsync_len;
	var->lower_margin -= var->vsync_len;

	if (screen_base)
		var->yoffset = (par->screen_base - screen_base) / linelen;
	else
		var->yoffset = 0;
	var->nonstd = 0;		/* what is this for? */
	var->activate = 0;
	return 0;
}

static int f_change_mode;
static struct falcon_hw f_new_mode;
static int f_pan_display;

static void falcon_get_par(struct atafb_par *par)
{
	unsigned long addr;
	struct falcon_hw *hw = &par->hw.falcon;

	hw->line_width = shifter_f030.scn_width;
	hw->line_offset = shifter_f030.off_next;
	hw->st_shift = videl.st_shift & 0x300;
	hw->f_shift = videl.f_shift;
	hw->vid_control = videl.control;
	hw->vid_mode = videl.mode;
	hw->sync = shifter.syncmode & 0x1;
	hw->xoffset = videl.xoffset & 0xf;
	hw->hht = videl.hht;
	hw->hbb = videl.hbb;
	hw->hbe = videl.hbe;
	hw->hdb = videl.hdb;
	hw->hde = videl.hde;
	hw->hss = videl.hss;
	hw->vft = videl.vft;
	hw->vbb = videl.vbb;
	hw->vbe = videl.vbe;
	hw->vdb = videl.vdb;
	hw->vde = videl.vde;
	hw->vss = videl.vss;

	addr = (shifter.bas_hi & 0xff) << 16 |
	       (shifter.bas_md & 0xff) << 8  |
	       (shifter.bas_lo & 0xff);
	par->screen_base = phys_to_virt(addr);

	/* derived parameters */
	hw->ste_mode = (hw->f_shift & 0x510) == 0 && hw->st_shift == 0x100;
	hw->mono = (hw->f_shift & 0x400) ||
	           ((hw->f_shift & 0x510) == 0 && hw->st_shift == 0x200);
}

static void falcon_set_par(struct atafb_par *par)
{
	f_change_mode = 0;

	/* only set screen_base if really necessary */
	if (current_par.screen_base != par->screen_base)
		fbhw->set_screen_base(par->screen_base);

	/* Don't touch any other registers if we keep the default resolution */
	if (DontCalcRes)
		return;

	/* Tell vbl-handler to change video mode.
	 * We change modes only on next VBL, to avoid desynchronisation
	 * (a shift to the right and wrap around by a random number of pixels
	 * in all monochrome modes).
	 * This seems to work on my Falcon.
	 */
	f_new_mode = par->hw.falcon;
	f_change_mode = 1;
}

static irqreturn_t falcon_vbl_switcher(int irq, void *dummy)
{
	struct falcon_hw *hw = &f_new_mode;

	if (f_change_mode) {
		f_change_mode = 0;

		if (hw->sync & 0x1) {
			/* Enable external pixelclock. This code only for ScreenWonder */
			*(volatile unsigned short *)0xffff9202 = 0xffbf;
		} else {
			/* Turn off external clocks. Read sets all output bits to 1. */
			*(volatile unsigned short *)0xffff9202;
		}
		shifter.syncmode = hw->sync;

		videl.hht = hw->hht;
		videl.hbb = hw->hbb;
		videl.hbe = hw->hbe;
		videl.hdb = hw->hdb;
		videl.hde = hw->hde;
		videl.hss = hw->hss;
		videl.vft = hw->vft;
		videl.vbb = hw->vbb;
		videl.vbe = hw->vbe;
		videl.vdb = hw->vdb;
		videl.vde = hw->vde;
		videl.vss = hw->vss;

		videl.f_shift = 0;	/* write enables Falcon palette, 0: 4 planes */
		if (hw->ste_mode) {
			videl.st_shift = hw->st_shift;	/* write enables STE palette */
		} else {
			/* IMPORTANT:
			 * set st_shift 0, so we can tell the screen-depth if f_shift == 0.
			 * Writing 0 to f_shift enables 4 plane Falcon mode but
			 * doesn't set st_shift. st_shift != 0 (!= 4planes) is impossible
			 * with Falcon palette.
			 */
			videl.st_shift = 0;
			/* now back to Falcon palette mode */
			videl.f_shift = hw->f_shift;
		}
		/* writing to st_shift changed scn_width and vid_mode */
		videl.xoffset = hw->xoffset;
		shifter_f030.scn_width = hw->line_width;
		shifter_f030.off_next = hw->line_offset;
		videl.control = hw->vid_control;
		videl.mode = hw->vid_mode;
	}
	if (f_pan_display) {
		f_pan_display = 0;
		videl.xoffset = current_par.hw.falcon.xoffset;
		shifter_f030.off_next = current_par.hw.falcon.line_offset;
	}
	return IRQ_HANDLED;
}

static int falcon_pan_display(struct fb_var_screeninfo *var,
			      struct fb_info *info)
{
	struct atafb_par *par = (struct atafb_par *)info->par;

	int xoffset;
	int bpp = info->var.bits_per_pixel;

	if (bpp == 1)
		var->xoffset = up(var->xoffset, 32);
	if (bpp != 16)
		par->hw.falcon.xoffset = var->xoffset & 15;
	else {
		par->hw.falcon.xoffset = 0;
		var->xoffset = up(var->xoffset, 2);
	}
	par->hw.falcon.line_offset = bpp *
		(info->var.xres_virtual - info->var.xres) / 16;
	if (par->hw.falcon.xoffset)
		par->hw.falcon.line_offset -= bpp;
	xoffset = var->xoffset - par->hw.falcon.xoffset;

	par->screen_base = screen_base +
	        (var->yoffset * info->var.xres_virtual + xoffset) * bpp / 8;
	if (fbhw->set_screen_base)
		fbhw->set_screen_base(par->screen_base);
	else
		return -EINVAL;		/* shouldn't happen */
	f_pan_display = 1;
	return 0;
}

static int falcon_setcolreg(unsigned int regno, unsigned int red,
			    unsigned int green, unsigned int blue,
			    unsigned int transp, struct fb_info *info)
{
	if (regno > 255)
		return 1;
	f030_col[regno] = (((red & 0xfc00) << 16) |
			   ((green & 0xfc00) << 8) |
			   ((blue & 0xfc00) >> 8));
	if (regno < 16) {
		shifter_tt.color_reg[regno] =
			(((red & 0xe000) >> 13) | ((red & 0x1000) >> 12) << 8) |
			(((green & 0xe000) >> 13) | ((green & 0x1000) >> 12) << 4) |
			((blue & 0xe000) >> 13) | ((blue & 0x1000) >> 12);
#ifdef FBCON_HAS_CFB16
		fbcon_cfb16_cmap[regno] = ((red & 0xf800) |
					   ((green & 0xfc00) >> 5) |
					   ((blue & 0xf800) >> 11));
#endif
	}
	return 0;
}

static int falcon_blank(int blank_mode)
{
	/* ++guenther: we can switch off graphics by changing VDB and VDE,
	 * so VIDEL doesn't hog the bus while saving.
	 * (this may affect usleep()).
	 */
	int vdb, vss, hbe, hss;

	if (mon_type == F_MON_SM)	/* this doesn't work on SM124 */
		return 1;

	vdb = current_par.VDB;
	vss = current_par.VSS;
	hbe = current_par.HBE;
	hss = current_par.HSS;

	if (blank_mode >= 1) {
		/* disable graphics output (this speeds up the CPU) ... */
		vdb = current_par.VFT + 1;
		/* ... and blank all lines */
		hbe = current_par.HHT + 2;
	}
	/* use VESA suspend modes on VGA monitors */
	if (mon_type == F_MON_VGA) {
		if (blank_mode == 2 || blank_mode == 4)
			vss = current_par.VFT + 1;
		if (blank_mode == 3 || blank_mode == 4)
			hss = current_par.HHT + 2;
	}

	videl.vdb = vdb;
	videl.vss = vss;
	videl.hbe = hbe;
	videl.hss = hss;

	return 0;
}

static int falcon_detect(void)
{
	struct atafb_par par;
	unsigned char fhw;

	/* Determine connected monitor and set monitor parameters */
	fhw = *(unsigned char *)0xffff8006;
	mon_type = fhw >> 6 & 0x3;
	/* bit 1 of fhw: 1=32 bit ram bus, 0=16 bit */
	f030_bus_width = fhw << 6 & 0x80;
	switch (mon_type) {
	case F_MON_SM:
		fb_info.monspecs.vfmin = 70;
		fb_info.monspecs.vfmax = 72;
		fb_info.monspecs.hfmin = 35713;
		fb_info.monspecs.hfmax = 35715;
		break;
	case F_MON_SC:
	case F_MON_TV:
		/* PAL...NTSC */
		fb_info.monspecs.vfmin = 49;	/* not 50, since TOS defaults to 49.9x Hz */
		fb_info.monspecs.vfmax = 60;
		fb_info.monspecs.hfmin = 15620;
		fb_info.monspecs.hfmax = 15755;
		break;
	}
	/* initialize hsync-len */
	f25.hsync = h_syncs[mon_type] / f25.t;
	f32.hsync = h_syncs[mon_type] / f32.t;
	if (fext.t)
		fext.hsync = h_syncs[mon_type] / fext.t;

	falcon_get_par(&par);
	falcon_encode_var(&atafb_predefined[0], &par);

	/* Detected mode is always the "autodetect" slot */
	return 1;
}

#endif /* ATAFB_FALCON */

/* ------------------- ST(E) specific functions ---------------------- */

#ifdef ATAFB_STE

static int stste_encode_fix(struct fb_fix_screeninfo *fix,
			    struct atafb_par *par)
{
	int mode;

	strcpy(fix->id, "Atari Builtin");
	fix->smem_start = (unsigned long)real_screen_base;
	fix->smem_len = screen_len;
	fix->type = FB_TYPE_INTERLEAVED_PLANES;
	fix->type_aux = 2;
	fix->visual = FB_VISUAL_PSEUDOCOLOR;
	mode = par->hw.st.mode & 3;
	if (mode == ST_HIGH) {
		fix->type = FB_TYPE_PACKED_PIXELS;
		fix->type_aux = 0;
		fix->visual = FB_VISUAL_MONO10;
	}
	if (ATARIHW_PRESENT(EXTD_SHIFTER)) {
		fix->xpanstep = 16;
		fix->ypanstep = 1;
	} else {
		fix->xpanstep = 0;
		fix->ypanstep = 0;
	}
	fix->ywrapstep = 0;
	fix->line_length = 0;
	fix->accel = FB_ACCEL_ATARIBLITT;
	return 0;
}

static int stste_decode_var(struct fb_var_screeninfo *var,
			    struct atafb_par *par)
{
	int xres = var->xres;
	int yres = var->yres;
	int bpp = var->bits_per_pixel;
	int linelen;
	int yres_virtual = var->yres_virtual;

	if (mono_moni) {
		if (bpp > 1 || xres > sttt_xres || yres > st_yres)
			return -EINVAL;
		par->hw.st.mode = ST_HIGH;
		xres = sttt_xres;
		yres = st_yres;
		bpp = 1;
	} else {
		if (bpp > 4 || xres > sttt_xres || yres > st_yres)
			return -EINVAL;
		if (bpp > 2) {
			if (xres > sttt_xres / 2 || yres > st_yres / 2)
				return -EINVAL;
			par->hw.st.mode = ST_LOW;
			xres = sttt_xres / 2;
			yres = st_yres / 2;
			bpp = 4;
		} else if (bpp > 1) {
			if (xres > sttt_xres || yres > st_yres / 2)
				return -EINVAL;
			par->hw.st.mode = ST_MID;
			xres = sttt_xres;
			yres = st_yres / 2;
			bpp = 2;
		} else
			return -EINVAL;
	}
	if (yres_virtual <= 0)
		yres_virtual = 0;
	else if (yres_virtual < yres)
		yres_virtual = yres;
	if (var->sync & FB_SYNC_EXT)
		par->hw.st.sync = (par->hw.st.sync & ~1) | 1;
	else
		par->hw.st.sync = (par->hw.st.sync & ~1);
	linelen = xres * bpp / 8;
	if (yres_virtual * linelen > screen_len && screen_len)
		return -EINVAL;
	if (yres * linelen > screen_len && screen_len)
		return -EINVAL;
	if (var->yoffset + yres > yres_virtual && yres_virtual)
		return -EINVAL;
	par->yres_virtual = yres_virtual;
	par->screen_base = screen_base + var->yoffset * linelen;
	return 0;
}

static int stste_encode_var(struct fb_var_screeninfo *var,
			    struct atafb_par *par)
{
	int linelen;
	memset(var, 0, sizeof(struct fb_var_screeninfo));
	var->red.offset = 0;
	var->red.length = ATARIHW_PRESENT(EXTD_SHIFTER) ? 4 : 3;
	var->red.msb_right = 0;
	var->grayscale = 0;

	var->pixclock = 31041;
	var->left_margin = 120;		/* these are incorrect */
	var->right_margin = 100;
	var->upper_margin = 8;
	var->lower_margin = 16;
	var->hsync_len = 140;
	var->vsync_len = 30;

	var->height = -1;
	var->width = -1;

	if (!(par->hw.st.sync & 1))
		var->sync = 0;
	else
		var->sync = FB_SYNC_EXT;

	switch (par->hw.st.mode & 3) {
	case ST_LOW:
		var->xres = sttt_xres / 2;
		var->yres = st_yres / 2;
		var->bits_per_pixel = 4;
		break;
	case ST_MID:
		var->xres = sttt_xres;
		var->yres = st_yres / 2;
		var->bits_per_pixel = 2;
		break;
	case ST_HIGH:
		var->xres = sttt_xres;
		var->yres = st_yres;
		var->bits_per_pixel = 1;
		break;
	}
	var->blue = var->green = var->red;
	var->transp.offset = 0;
	var->transp.length = 0;
	var->transp.msb_right = 0;
	var->xres_virtual = sttt_xres_virtual;
	linelen = var->xres_virtual * var->bits_per_pixel / 8;
	ovsc_addlen = linelen * (sttt_yres_virtual - st_yres);

	if (!use_hwscroll)
		var->yres_virtual = var->yres;
	else if (screen_len) {
		if (par->yres_virtual)
			var->yres_virtual = par->yres_virtual;
		else
			/* yres_virtual == 0 means use maximum */
			var->yres_virtual = screen_len / linelen;
	} else {
		if (hwscroll < 0)
			var->yres_virtual = 2 * var->yres;
		else
			var->yres_virtual = var->yres + hwscroll * 16;
	}
	var->xoffset = 0;
	if (screen_base)
		var->yoffset = (par->screen_base - screen_base) / linelen;
	else
		var->yoffset = 0;
	var->nonstd = 0;
	var->activate = 0;
	var->vmode = FB_VMODE_NONINTERLACED;
	return 0;
}

static void stste_get_par(struct atafb_par *par)
{
	unsigned long addr;
	par->hw.st.mode = shifter_tt.st_shiftmode;
	par->hw.st.sync = shifter.syncmode;
	addr = ((shifter.bas_hi & 0xff) << 16) |
	       ((shifter.bas_md & 0xff) << 8);
	if (ATARIHW_PRESENT(EXTD_SHIFTER))
		addr |= (shifter.bas_lo & 0xff);
	par->screen_base = phys_to_virt(addr);
}

static void stste_set_par(struct atafb_par *par)
{
	shifter_tt.st_shiftmode = par->hw.st.mode;
	shifter.syncmode = par->hw.st.sync;
	/* only set screen_base if really necessary */
	if (current_par.screen_base != par->screen_base)
		fbhw->set_screen_base(par->screen_base);
}

static int stste_setcolreg(unsigned int regno, unsigned int red,
			   unsigned int green, unsigned int blue,
			   unsigned int transp, struct fb_info *info)
{
	if (regno > 15)
		return 1;
	red >>= 12;
	blue >>= 12;
	green >>= 12;
	if (ATARIHW_PRESENT(EXTD_SHIFTER))
		shifter_tt.color_reg[regno] =
			(((red & 0xe) >> 1) | ((red & 1) << 3) << 8) |
			(((green & 0xe) >> 1) | ((green & 1) << 3) << 4) |
			((blue & 0xe) >> 1) | ((blue & 1) << 3);
	else
		shifter_tt.color_reg[regno] =
			((red & 0xe) << 7) |
			((green & 0xe) << 3) |
			((blue & 0xe) >> 1);
	return 0;
}

static int stste_detect(void)
{
	struct atafb_par par;

	/* Determine the connected monitor: The DMA sound must be
	 * disabled before reading the MFP GPIP, because the Sound
	 * Done Signal and the Monochrome Detect are XORed together!
	 */
	if (ATARIHW_PRESENT(PCM_8BIT)) {
		tt_dmasnd.ctrl = DMASND_CTRL_OFF;
		udelay(20);		/* wait a while for things to settle down */
	}
	mono_moni = (mfp.par_dt_reg & 0x80) == 0;

	stste_get_par(&par);
	stste_encode_var(&atafb_predefined[0], &par);

	if (!ATARIHW_PRESENT(EXTD_SHIFTER))
		use_hwscroll = 0;
	return 1;
}

static void stste_set_screen_base(void *s_base)
{
	unsigned long addr;
	addr = virt_to_phys(s_base);
	/* Setup Screen Memory */
	shifter.bas_hi = (unsigned char)((addr & 0xff0000) >> 16);
	shifter.bas_md = (unsigned char)((addr & 0x00ff00) >> 8);
	if (ATARIHW_PRESENT(EXTD_SHIFTER))
		shifter.bas_lo = (unsigned char)(addr & 0x0000ff);
}

#endif /* ATAFB_STE */

/* Switching the screen size should be done during vsync, otherwise
 * the margins may get messed up. This is a well known problem of
 * the ST's video system.
 *
 * Unfortunately there is hardly any way to find the vsync, as the
 * vertical blank interrupt is no longer in time on machines with
 * overscan type modifications.
 *
 * We can, however, use Timer B to safely detect the black shoulder,
 * but then we've got to guess an appropriate delay to find the vsync.
 * This might not work on every machine.
 *
 * martin_rogge @ ki.maus.de, 8th Aug 1995
 */

#define LINE_DELAY  (mono_moni ? 30 : 70)
#define SYNC_DELAY  (mono_moni ? 1500 : 2000)

/* SWITCH_ACIA may be used for Falcon (ScreenBlaster III internal!) */
static void st_ovsc_switch(void)
{
	unsigned long flags;
	register unsigned char old, new;

	if (!(atari_switches & ATARI_SWITCH_OVSC_MASK))
		return;
	local_irq_save(flags);

	mfp.tim_ct_b = 0x10;
	mfp.active_edge |= 8;
	mfp.tim_ct_b = 0;
	mfp.tim_dt_b = 0xf0;
	mfp.tim_ct_b = 8;
	while (mfp.tim_dt_b > 1)	/* TOS does it this way, don't ask why */
		;
	new = mfp.tim_dt_b;
	do {
		udelay(LINE_DELAY);
		old = new;
		new = mfp.tim_dt_b;
	} while (old != new);
	mfp.tim_ct_b = 0x10;
	udelay(SYNC_DELAY);

	if (atari_switches & ATARI_SWITCH_OVSC_IKBD)
		acia.key_ctrl = ACIA_DIV64 | ACIA_D8N1S | ACIA_RHTID | ACIA_RIE;
	if (atari_switches & ATARI_SWITCH_OVSC_MIDI)
		acia.mid_ctrl = ACIA_DIV16 | ACIA_D8N1S | ACIA_RHTID;
	if (atari_switches & (ATARI_SWITCH_OVSC_SND6|ATARI_SWITCH_OVSC_SND7)) {
		sound_ym.rd_data_reg_sel = 14;
		sound_ym.wd_data = sound_ym.rd_data_reg_sel |
				   ((atari_switches & ATARI_SWITCH_OVSC_SND6) ? 0x40:0) |
				   ((atari_switches & ATARI_SWITCH_OVSC_SND7) ? 0x80:0);
	}
	local_irq_restore(flags);
}

/* ------------------- External Video ---------------------- */

#ifdef ATAFB_EXT

static int ext_encode_fix(struct fb_fix_screeninfo *fix, struct atafb_par *par)
{
	strcpy(fix->id, "Unknown Extern");
	fix->smem_start = (unsigned long)external_addr;
	fix->smem_len = PAGE_ALIGN(external_len);
	if (external_depth == 1) {
		fix->type = FB_TYPE_PACKED_PIXELS;
		/* The letters 'n' and 'i' in the "atavideo=external:" stand
		 * for "normal" and "inverted", rsp., in the monochrome case */
		fix->visual =
			(external_pmode == FB_TYPE_INTERLEAVED_PLANES ||
			 external_pmode == FB_TYPE_PACKED_PIXELS) ?
				FB_VISUAL_MONO10 : FB_VISUAL_MONO01;
	} else {
		/* Use STATIC if we don't know how to access color registers */
		int visual = external_vgaiobase ?
					 FB_VISUAL_PSEUDOCOLOR :
					 FB_VISUAL_STATIC_PSEUDOCOLOR;
		switch (external_pmode) {
		case -1:		/* truecolor */
			fix->type = FB_TYPE_PACKED_PIXELS;
			fix->visual = FB_VISUAL_TRUECOLOR;
			break;
		case FB_TYPE_PACKED_PIXELS:
			fix->type = FB_TYPE_PACKED_PIXELS;
			fix->visual = visual;
			break;
		case FB_TYPE_PLANES:
			fix->type = FB_TYPE_PLANES;
			fix->visual = visual;
			break;
		case FB_TYPE_INTERLEAVED_PLANES:
			fix->type = FB_TYPE_INTERLEAVED_PLANES;
			fix->type_aux = 2;
			fix->visual = visual;
			break;
		}
	}
	fix->xpanstep = 0;
	fix->ypanstep = 0;
	fix->ywrapstep = 0;
	fix->line_length = 0;
	return 0;
}

static int ext_decode_var(struct fb_var_screeninfo *var, struct atafb_par *par)
{
	struct fb_var_screeninfo *myvar = &atafb_predefined[0];

	if (var->bits_per_pixel > myvar->bits_per_pixel ||
	    var->xres > myvar->xres ||
	    var->xres_virtual > myvar->xres_virtual ||
	    var->yres > myvar->yres ||
	    var->xoffset > 0 ||
	    var->yoffset > 0)
		return -EINVAL;
	return 0;
}

static int ext_encode_var(struct fb_var_screeninfo *var, struct atafb_par *par)
{
	memset(var, 0, sizeof(struct fb_var_screeninfo));
	var->red.offset = 0;
	var->red.length = (external_pmode == -1) ? external_depth / 3 :
			(external_vgaiobase ? external_bitspercol : 0);
	var->red.msb_right = 0;
	var->grayscale = 0;

	var->pixclock = 31041;
	var->left_margin = 120;		/* these are surely incorrect */
	var->right_margin = 100;
	var->upper_margin = 8;
	var->lower_margin = 16;
	var->hsync_len = 140;
	var->vsync_len = 30;

	var->height = -1;
	var->width = -1;

	var->sync = 0;

	var->xres = external_xres;
	var->yres = external_yres;
	var->xres_virtual = external_xres_virtual;
	var->bits_per_pixel = external_depth;

	var->blue = var->green = var->red;
	var->transp.offset = 0;
	var->transp.length = 0;
	var->transp.msb_right = 0;
	var->yres_virtual = var->yres;
	var->xoffset = 0;
	var->yoffset = 0;
	var->nonstd = 0;
	var->activate = 0;
	var->vmode = FB_VMODE_NONINTERLACED;
	return 0;
}

static void ext_get_par(struct atafb_par *par)
{
	par->screen_base = external_addr;
}

static void ext_set_par(struct atafb_par *par)
{
}

#define OUTB(port,val) \
	*((unsigned volatile char *) ((port)+external_vgaiobase)) = (val)
#define INB(port) \
	(*((unsigned volatile char *) ((port)+external_vgaiobase)))
#define DACDelay				\
	do {					\
		unsigned char tmp = INB(0x3da);	\
		tmp = INB(0x3da);			\
	} while (0)

static int ext_setcolreg(unsigned int regno, unsigned int red,
			 unsigned int green, unsigned int blue,
			 unsigned int transp, struct fb_info *info)
{
	unsigned char colmask = (1 << external_bitspercol) - 1;

	if (!external_vgaiobase)
		return 1;

	switch (external_card_type) {
	case IS_VGA:
		OUTB(0x3c8, regno);
		DACDelay;
		OUTB(0x3c9, red & colmask);
		DACDelay;
		OUTB(0x3c9, green & colmask);
		DACDelay;
		OUTB(0x3c9, blue & colmask);
		DACDelay;
		return 0;

	case IS_MV300:
		OUTB((MV300_reg[regno] << 2) + 1, red);
		OUTB((MV300_reg[regno] << 2) + 1, green);
		OUTB((MV300_reg[regno] << 2) + 1, blue);
		return 0;

	default:
		return 1;
	}
}

static int ext_detect(void)
{
	struct fb_var_screeninfo *myvar = &atafb_predefined[0];
	struct atafb_par dummy_par;

	myvar->xres = external_xres;
	myvar->xres_virtual = external_xres_virtual;
	myvar->yres = external_yres;
	myvar->bits_per_pixel = external_depth;
	ext_encode_var(myvar, &dummy_par);
	return 1;
}

#endif /* ATAFB_EXT */

/* ------ This is the same for most hardware types -------- */

static void set_screen_base(void *s_base)
{
	unsigned long addr;

	addr = virt_to_phys(s_base);
	/* Setup Screen Memory */
	shifter.bas_hi = (unsigned char)((addr & 0xff0000) >> 16);
	shifter.bas_md = (unsigned char)((addr & 0x00ff00) >> 8);
	shifter.bas_lo = (unsigned char)(addr & 0x0000ff);
}

static int pan_display(struct fb_var_screeninfo *var, struct fb_info *info)
{
	struct atafb_par *par = (struct atafb_par *)info->par;

	if (!fbhw->set_screen_base ||
	    (!ATARIHW_PRESENT(EXTD_SHIFTER) && var->xoffset))
		return -EINVAL;
	var->xoffset = up(var->xoffset, 16);
	par->screen_base = screen_base +
	        (var->yoffset * info->var.xres_virtual + var->xoffset)
	        * info->var.bits_per_pixel / 8;
	fbhw->set_screen_base(par->screen_base);
	return 0;
}

/* ------------ Interfaces to hardware functions ------------ */

#ifdef ATAFB_TT
static struct fb_hwswitch tt_switch = {
	.detect		= tt_detect,
	.encode_fix	= tt_encode_fix,
	.decode_var	= tt_decode_var,
	.encode_var	= tt_encode_var,
	.get_par	= tt_get_par,
	.set_par	= tt_set_par,
	.set_screen_base = set_screen_base,
	.pan_display	= pan_display,
};
#endif

#ifdef ATAFB_FALCON
static struct fb_hwswitch falcon_switch = {
	.detect		= falcon_detect,
	.encode_fix	= falcon_encode_fix,
	.decode_var	= falcon_decode_var,
	.encode_var	= falcon_encode_var,
	.get_par	= falcon_get_par,
	.set_par	= falcon_set_par,
	.set_screen_base = set_screen_base,
	.blank		= falcon_blank,
	.pan_display	= falcon_pan_display,
};
#endif

#ifdef ATAFB_STE
static struct fb_hwswitch st_switch = {
	.detect		= stste_detect,
	.encode_fix	= stste_encode_fix,
	.decode_var	= stste_decode_var,
	.encode_var	= stste_encode_var,
	.get_par	= stste_get_par,
	.set_par	= stste_set_par,
	.set_screen_base = stste_set_screen_base,
	.pan_display	= pan_display
};
#endif

#ifdef ATAFB_EXT
static struct fb_hwswitch ext_switch = {
	.detect		= ext_detect,
	.encode_fix	= ext_encode_fix,
	.decode_var	= ext_decode_var,
	.encode_var	= ext_encode_var,
	.get_par	= ext_get_par,
	.set_par	= ext_set_par,
};
#endif

static void ata_get_par(struct atafb_par *par)
{
	if (current_par_valid)
		*par = current_par;
	else
		fbhw->get_par(par);
}

static void ata_set_par(struct atafb_par *par)
{
	fbhw->set_par(par);
	current_par = *par;
	current_par_valid = 1;
}


/* =========================================================== */
/* ============== Hardware Independent Functions ============= */
/* =========================================================== */

/* used for hardware scrolling */

static int do_fb_set_var(struct fb_var_screeninfo *var, int isactive)
{
	int err, activate;
	struct atafb_par par;

	err = fbhw->decode_var(var, &par);
	if (err)
		return err;
	activate = var->activate;
	if (((var->activate & FB_ACTIVATE_MASK) == FB_ACTIVATE_NOW) && isactive)
		ata_set_par(&par);
	fbhw->encode_var(var, &par);
	var->activate = activate;
	return 0;
}

static int atafb_get_fix(struct fb_fix_screeninfo *fix, struct fb_info *info)
{
	struct atafb_par par;
	int err;
	// Get fix directly (case con == -1 before)??
	err = fbhw->decode_var(&info->var, &par);
	if (err)
		return err;
	memset(fix, 0, sizeof(struct fb_fix_screeninfo));
	return fbhw->encode_fix(fix, &par);
}

static int atafb_get_var(struct fb_var_screeninfo *var, struct fb_info *info)
{
	struct atafb_par par;

	ata_get_par(&par);
	fbhw->encode_var(var, &par);

	return 0;
}

// No longer called by fbcon!
// Still called by set_var internally

static void atafb_set_disp(struct fb_info *info)
{
	atafb_get_var(&info->var, info);
	atafb_get_fix(&info->fix, info);

	info->screen_base = (void *)info->fix.smem_start;

	switch (info->fix.type) {
	case FB_TYPE_INTERLEAVED_PLANES:
		switch (info->var.bits_per_pixel) {
		case 2:
			// display->dispsw = &fbcon_iplan2p2;
			break;
		case 4:
			// display->dispsw = &fbcon_iplan2p4;
			break;
		case 8:
			// display->dispsw = &fbcon_iplan2p8;
			break;
		}
		break;
	case FB_TYPE_PACKED_PIXELS:
		switch (info->var.bits_per_pixel) {
#ifdef FBCON_HAS_MFB
		case 1:
			// display->dispsw = &fbcon_mfb;
			break;
#endif
#ifdef FBCON_HAS_CFB8
		case 8:
			// display->dispsw = &fbcon_cfb8;
			break;
#endif
#ifdef FBCON_HAS_CFB16
		case 16:
			// display->dispsw = &fbcon_cfb16;
			// display->dispsw_data = fbcon_cfb16_cmap;
			break;
#endif
		}
		break;
	}
}

static int atafb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
			   u_int transp, struct fb_info *info)
{
	red >>= 8;
	green >>= 8;
	blue >>= 8;

	return info->fbops->fb_setcolreg(regno, red, green, blue, transp, info);
}

static int
atafb_pan_display(struct fb_var_screeninfo *var, struct fb_info *info)
{
	int xoffset = var->xoffset;
	int yoffset = var->yoffset;
	int err;

	if (var->vmode & FB_VMODE_YWRAP) {
		if (yoffset < 0 || yoffset >= info->var.yres_virtual || xoffset)
			return -EINVAL;
	} else {
		if (xoffset + info->var.xres > info->var.xres_virtual ||
		    yoffset + info->var.yres > info->var.yres_virtual)
			return -EINVAL;
	}

	if (fbhw->pan_display) {
		err = fbhw->pan_display(var, info);
		if (err)
			return err;
	} else
		return -EINVAL;

	info->var.xoffset = xoffset;
	info->var.yoffset = yoffset;

	if (var->vmode & FB_VMODE_YWRAP)
		info->var.vmode |= FB_VMODE_YWRAP;
	else
		info->var.vmode &= ~FB_VMODE_YWRAP;

	return 0;
}

/*
 * generic drawing routines; imageblit needs updating for image depth > 1
 */

#if BITS_PER_LONG == 32
#define BYTES_PER_LONG	4
#define SHIFT_PER_LONG	5
#elif BITS_PER_LONG == 64
#define BYTES_PER_LONG	8
#define SHIFT_PER_LONG	6
#else
#define Please update me
#endif


static void atafb_fillrect(struct fb_info *info, const struct fb_fillrect *rect)
{
	struct atafb_par *par = (struct atafb_par *)info->par;
	int x2, y2;
	u32 width, height;

	if (!rect->width || !rect->height)
		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 < info->var.xres_virtual ? x2 : info->var.xres_virtual;
	y2 = y2 < info->var.yres_virtual ? y2 : info->var.yres_virtual;
	width = x2 - rect->dx;
	height = y2 - rect->dy;

	if (info->var.bits_per_pixel == 1)
		atafb_mfb_fillrect(info, par->next_line, rect->color,
				   rect->dy, rect->dx, height, width);
	else if (info->var.bits_per_pixel == 2)
		atafb_iplan2p2_fillrect(info, par->next_line, rect->color,
					rect->dy, rect->dx, height, width);
	else if (info->var.bits_per_pixel == 4)
		atafb_iplan2p4_fillrect(info, par->next_line, rect->color,
					rect->dy, rect->dx, height, width);
	else
		atafb_iplan2p8_fillrect(info, par->next_line, rect->color,
					rect->dy, rect->dx, height, width);

	return;
}

static void atafb_copyarea(struct fb_info *info, const struct fb_copyarea *area)
{
	struct atafb_par *par = (struct atafb_par *)info->par;
	int x2, y2;
	u32 dx, dy, sx, sy, width, height;
	int rev_copy = 0;

	/* clip the destination */
	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 < info->var.xres_virtual ? x2 : info->var.xres_virtual;
	y2 = y2 < info->var.yres_virtual ? y2 : info->var.yres_virtual;
	width = x2 - dx;
	height = y2 - dy;

	/* update sx,sy */
	sx = area->sx + (dx - area->dx);
	sy = area->sy + (dy - area->dy);

	/* the source must be completely inside the virtual screen */
	if (sx < 0 || sy < 0 || (sx + width) > info->var.xres_virtual ||
	    (sy + height) > info->var.yres_virtual)
		return;

	if (dy > sy || (dy == sy && dx > sx)) {
		dy += height;
		sy += height;
		rev_copy = 1;
	}

	if (info->var.bits_per_pixel == 1)
		atafb_mfb_copyarea(info, par->next_line, sy, sx, dy, dx, height, width);
	else if (info->var.bits_per_pixel == 2)
		atafb_iplan2p2_copyarea(info, par->next_line, sy, sx, dy, dx, height, width);
	else if (info->var.bits_per_pixel == 4)
		atafb_iplan2p4_copyarea(info, par->next_line, sy, sx, dy, dx, height, width);
	else
		atafb_iplan2p8_copyarea(info, par->next_line, sy, sx, dy, dx, height, width);

	return;
}

static void atafb_imageblit(struct fb_info *info, const struct fb_image *image)
{
	struct atafb_par *par = (struct atafb_par *)info->par;
	int x2, y2;
	unsigned long *dst;
	int dst_idx;
	const char *src;
	u32 dx, dy, width, height, pitch;

	/*
	 * We could use hardware clipping but on many cards you get around
	 * hardware clipping by writing to framebuffer directly like we are
	 * doing here.
	 */
	x2 = image->dx + image->width;
	y2 = image->dy + image->height;
	dx = image->dx;
	dy = image->dy;
	x2 = x2 < info->var.xres_virtual ? x2 : info->var.xres_virtual;
	y2 = y2 < info->var.yres_virtual ? y2 : info->var.yres_virtual;
	width = x2 - dx;
	height = y2 - dy;

	if (image->depth == 1) {
		// used for font data
		dst = (unsigned long *)
			((unsigned long)info->screen_base & ~(BYTES_PER_LONG - 1));
		dst_idx = ((unsigned long)info->screen_base & (BYTES_PER_LONG - 1)) * 8;
		dst_idx += dy * par->next_line * 8 + dx;
		src = image->data;
		pitch = (image->width + 7) / 8;
		while (height--) {

			if (info->var.bits_per_pixel == 1)
				atafb_mfb_linefill(info, par->next_line,
						   dy, dx, width, src,
						   image->bg_color, image->fg_color);
			else if (info->var.bits_per_pixel == 2)
				atafb_iplan2p2_linefill(info, par->next_line,
							dy, dx, width, src,
							image->bg_color, image->fg_color);
			else if (info->var.bits_per_pixel == 4)
				atafb_iplan2p4_linefill(info, par->next_line,
							dy, dx, width, src,
							image->bg_color, image->fg_color);
			else
				atafb_iplan2p8_linefill(info, par->next_line,
							dy, dx, width, src,
							image->bg_color, image->fg_color);
			dy++;
			src += pitch;
		}
	} else {
		// only used for logo; broken
		c2p(info->screen_base, image->data, dx, dy, width, height,
		    par->next_line, par->next_plane, image->width,
		    info->var.bits_per_pixel);
	}
}

static int
atafb_ioctl(struct fb_info *info, unsigned int cmd, unsigned long arg)
{
	switch (cmd) {
#ifdef FBCMD_GET_CURRENTPAR
	case FBCMD_GET_CURRENTPAR:
		if (copy_to_user((void *)arg, (void *)&current_par,
				 sizeof(struct atafb_par)))
			return -EFAULT;
		return 0;
#endif
#ifdef FBCMD_SET_CURRENTPAR
	case FBCMD_SET_CURRENTPAR:
		if (copy_from_user((void *)&current_par, (void *)arg,
				   sizeof(struct atafb_par)))
			return -EFAULT;
		ata_set_par(&current_par);
		return 0;
#endif
	}
	return -EINVAL;
}

/* (un)blank/poweroff
 * 0 = unblank
 * 1 = blank
 * 2 = suspend vsync
 * 3 = suspend hsync
 * 4 = off
 */
static int atafb_blank(int blank, struct fb_info *info)
{
	unsigned short black[16];
	struct fb_cmap cmap;
	if (fbhw->blank && !fbhw->blank(blank))
		return 1;
	if (blank) {
		memset(black, 0, 16 * sizeof(unsigned short));
		cmap.red = black;
		cmap.green = black;
		cmap.blue = black;
		cmap.transp = NULL;
		cmap.start = 0;
		cmap.len = 16;
		fb_set_cmap(&cmap, info);
	}
#if 0
	else
		do_install_cmap(info);
#endif
	return 0;
}

	/*
	 * New fbcon interface ...
	 */

	 /* check var by decoding var into hw par, rounding if necessary,
	  * then encoding hw par back into new, validated var */
static int atafb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
{
	int err;
	struct atafb_par par;

	/* Validate wanted screen parameters */
	// if ((err = ata_decode_var(var, &par)))
	err = fbhw->decode_var(var, &par);
	if (err)
		return err;

	/* Encode (possibly rounded) screen parameters */
	fbhw->encode_var(var, &par);
	return 0;
}

	/* actually set hw par by decoding var, then setting hardware from
	 * hw par just decoded */
static int atafb_set_par(struct fb_info *info)
{
	struct atafb_par *par = (struct atafb_par *)info->par;

	/* Decode wanted screen parameters */
	fbhw->decode_var(&info->var, par);
	fbhw->encode_fix(&info->fix, par);

	/* Set new videomode */
	ata_set_par(par);

	return 0;
}


static struct fb_ops atafb_ops = {
	.owner =	THIS_MODULE,
	.fb_check_var	= atafb_check_var,
	.fb_set_par	= atafb_set_par,
	.fb_setcolreg	= atafb_setcolreg,
	.fb_blank =	atafb_blank,
	.fb_pan_display	= atafb_pan_display,
	.fb_fillrect	= atafb_fillrect,
	.fb_copyarea	= atafb_copyarea,
	.fb_imageblit	= atafb_imageblit,
	.fb_ioctl =	atafb_ioctl,
};

static void check_default_par(int detected_mode)
{
	char default_name[10];
	int i;
	struct fb_var_screeninfo var;
	unsigned long min_mem;

	/* First try the user supplied mode */
	if (default_par) {
		var = atafb_predefined[default_par - 1];
		var.activate = FB_ACTIVATE_TEST;
		if (do_fb_set_var(&var, 1))
			default_par = 0;	/* failed */
	}
	/* Next is the autodetected one */
	if (!default_par) {
		var = atafb_predefined[detected_mode - 1]; /* autodetect */
		var.activate = FB_ACTIVATE_TEST;
		if (!do_fb_set_var(&var, 1))
			default_par = detected_mode;
	}
	/* If that also failed, try some default modes... */
	if (!default_par) {
		/* try default1, default2... */
		for (i = 1; i < 10; i++) {
			sprintf(default_name,"default%d", i);
			default_par = get_video_mode(default_name);
			if (!default_par)
				panic("can't set default video mode");
			var = atafb_predefined[default_par - 1];
			var.activate = FB_ACTIVATE_TEST;
			if (!do_fb_set_var(&var,1))
				break;	/* ok */
		}
	}
	min_mem = var.xres_virtual * var.yres_virtual * var.bits_per_pixel / 8;
	if (default_mem_req < min_mem)
		default_mem_req = min_mem;
}

#ifdef ATAFB_EXT
static void __init atafb_setup_ext(char *spec)
{
	int xres, xres_virtual, yres, depth, planes;
	unsigned long addr, len;
	char *p;

	/* Format is: <xres>;<yres>;<depth>;<plane organ.>;
	 *            <screen mem addr>
	 *	      [;<screen mem length>[;<vgaiobase>[;<bits-per-col>[;<colorreg-type>
	 *	      [;<xres-virtual>]]]]]
	 *
	 * 09/23/97	Juergen
	 * <xres_virtual>:	hardware's x-resolution (f.e. ProMST)
	 *
	 * Even xres_virtual is available, we neither support panning nor hw-scrolling!
	 */
	p = strsep(&spec, ";");
	if (!p || !*p)
		return;
	xres_virtual = xres = simple_strtoul(p, NULL, 10);
	if (xres <= 0)
		return;

	p = strsep(&spec, ";");
	if (!p || !*p)
		return;
	yres = simple_strtoul(p, NULL, 10);
	if (yres <= 0)
		return;

	p = strsep(&spec, ";");
	if (!p || !*p)
		return;
	depth = simple_strtoul(p, NULL, 10);
	if (depth != 1 && depth != 2 && depth != 4 && depth != 8 &&
	    depth != 16 && depth != 24)
		return;

	p = strsep(&spec, ";");
	if (!p || !*p)
		return;
	if (*p == 'i')
		planes = FB_TYPE_INTERLEAVED_PLANES;
	else if (*p == 'p')
		planes = FB_TYPE_PACKED_PIXELS;
	else if (*p == 'n')
		planes = FB_TYPE_PLANES;
	else if (*p == 't')
		planes = -1;		/* true color */
	else
		return;

	p = strsep(&spec, ";");
	if (!p || !*p)
		return;
	addr = simple_strtoul(p, NULL, 0);

	p = strsep(&spec, ";");
	if (!p || !*p)
		len = xres * yres * depth / 8;
	else
		len = simple_strtoul(p, NULL, 0);

	p = strsep(&spec, ";");
	if (p && *p)
		external_vgaiobase = simple_strtoul(p, NULL, 0);

	p = strsep(&spec, ";");
	if (p && *p) {
		external_bitspercol = simple_strtoul(p, NULL, 0);
		if (external_bitspercol > 8)
			external_bitspercol = 8;
		else if (external_bitspercol < 1)
			external_bitspercol = 1;
	}

	p = strsep(&spec, ";");
	if (p && *p) {
		if (!strcmp(p, "vga"))
			external_card_type = IS_VGA;
		if (!strcmp(p, "mv300"))
			external_card_type = IS_MV300;
	}

	p = strsep(&spec, ";");
	if (p && *p) {
		xres_virtual = simple_strtoul(p, NULL, 10);
		if (xres_virtual < xres)
			xres_virtual = xres;
		if (xres_virtual * yres * depth / 8 > len)
			len = xres_virtual * yres * depth / 8;
	}

	external_xres = xres;
	external_xres_virtual = xres_virtual;
	external_yres = yres;
	external_depth = depth;
	external_pmode = planes;
	external_addr = (void *)addr;
	external_len = len;

	if (external_card_type == IS_MV300) {
		switch (external_depth) {
		case 1:
			MV300_reg = MV300_reg_1bit;
			break;
		case 4:
			MV300_reg = MV300_reg_4bit;
			break;
		case 8:
			MV300_reg = MV300_reg_8bit;
			break;
		}
	}
}
#endif /* ATAFB_EXT */

static void __init atafb_setup_int(char *spec)
{
	/* Format to config extended internal video hardware like OverScan:
	 * "internal:<xres>;<yres>;<xres_max>;<yres_max>;<offset>"
	 * Explanation:
	 * <xres>: x-resolution
	 * <yres>: y-resolution
	 * The following are only needed if you have an overscan which
	 * needs a black border:
	 * <xres_max>: max. length of a line in pixels your OverScan hardware would allow
	 * <yres_max>: max. number of lines your OverScan hardware would allow
	 * <offset>: Offset from physical beginning to visible beginning
	 *	  of screen in bytes
	 */
	int xres;
	char *p;

	if (!(p = strsep(&spec, ";")) || !*p)
		return;
	xres = simple_strtoul(p, NULL, 10);
	if (!(p = strsep(&spec, ";")) || !*p)
		return;
	sttt_xres = xres;
	tt_yres = st_yres = simple_strtoul(p, NULL, 10);
	if ((p = strsep(&spec, ";")) && *p)
		sttt_xres_virtual = simple_strtoul(p, NULL, 10);
	if ((p = strsep(&spec, ";")) && *p)
		sttt_yres_virtual = simple_strtoul(p, NULL, 0);
	if ((p = strsep(&spec, ";")) && *p)
		ovsc_offset = simple_strtoul(p, NULL, 0);

	if (ovsc_offset || (sttt_yres_virtual != st_yres))
		use_hwscroll = 0;
}

#ifdef ATAFB_FALCON
static void __init atafb_setup_mcap(char *spec)
{
	char *p;
	int vmin, vmax, hmin, hmax;

	/* Format for monitor capabilities is: <Vmin>;<Vmax>;<Hmin>;<Hmax>
	 * <V*> vertical freq. in Hz
	 * <H*> horizontal freq. in kHz
	 */
	if (!(p = strsep(&spec, ";")) || !*p)
		return;
	vmin = simple_strtoul(p, NULL, 10);
	if (vmin <= 0)
		return;
	if (!(p = strsep(&spec, ";")) || !*p)
		return;
	vmax = simple_strtoul(p, NULL, 10);
	if (vmax <= 0 || vmax <= vmin)
		return;
	if (!(p = strsep(&spec, ";")) || !*p)
		return;
	hmin = 1000 * simple_strtoul(p, NULL, 10);
	if (hmin <= 0)
		return;
	if (!(p = strsep(&spec, "")) || !*p)
		return;
	hmax = 1000 * simple_strtoul(p, NULL, 10);
	if (hmax <= 0 || hmax <= hmin)
		return;

	fb_info.monspecs.vfmin = vmin;
	fb_info.monspecs.vfmax = vmax;
	fb_info.monspecs.hfmin = hmin;
	fb_info.monspecs.hfmax = hmax;
}
#endif /* ATAFB_FALCON */

static void __init atafb_setup_user(char *spec)
{
	/* Format of user defined video mode is: <xres>;<yres>;<depth>
	 */
	char *p;
	int xres, yres, depth, temp;

	p = strsep(&spec, ";");
	if (!p || !*p)
		return;
	xres = simple_strtoul(p, NULL, 10);
	p = strsep(&spec, ";");
	if (!p || !*p)
		return;
	yres = simple_strtoul(p, NULL, 10);
	p = strsep(&spec, "");
	if (!p || !*p)
		return;
	depth = simple_strtoul(p, NULL, 10);
	temp = get_video_mode("user0");
	if (temp) {
		default_par = temp;
		atafb_predefined[default_par - 1].xres = xres;
		atafb_predefined[default_par - 1].yres = yres;
		atafb_predefined[default_par - 1].bits_per_pixel = depth;
	}
}

int __init atafb_setup(char *options)
{
	char *this_opt;
	int temp;

	if (!options || !*options)
		return 0;

	while ((this_opt = strsep(&options, ",")) != NULL) {
		if (!*this_opt)
			continue;
		if ((temp = get_video_mode(this_opt))) {
			default_par = temp;
			mode_option = this_opt;
		} else if (!strcmp(this_opt, "inverse"))
			inverse = 1;
		else if (!strncmp(this_opt, "hwscroll_", 9)) {
			hwscroll = simple_strtoul(this_opt + 9, NULL, 10);
			if (hwscroll < 0)
				hwscroll = 0;
			if (hwscroll > 200)
				hwscroll = 200;
		}
#ifdef ATAFB_EXT
		else if (!strcmp(this_opt, "mv300")) {
			external_bitspercol = 8;
			external_card_type = IS_MV300;
		} else if (!strncmp(this_opt, "external:", 9))
			atafb_setup_ext(this_opt + 9);
#endif
		else if (!strncmp(this_opt, "internal:", 9))
			atafb_setup_int(this_opt + 9);
#ifdef ATAFB_FALCON
		else if (!strncmp(this_opt, "eclock:", 7)) {
			fext.f = simple_strtoul(this_opt + 7, NULL, 10);
			/* external pixelclock in kHz --> ps */
			fext.t = 1000000000 / fext.f;
			fext.f *= 1000;
		} else if (!strncmp(this_opt, "monitorcap:", 11))
			atafb_setup_mcap(this_opt + 11);
#endif
		else if (!strcmp(this_opt, "keep"))
			DontCalcRes = 1;
		else if (!strncmp(this_opt, "R", 1))
			atafb_setup_user(this_opt + 1);
	}
	return 0;
}

int __init atafb_init(void)
{
	int pad;
	int detected_mode;
	unsigned int defmode = 0;
	unsigned long mem_req;

#ifndef MODULE
	char *option = NULL;

	if (fb_get_options("atafb", &option))
		return -ENODEV;
	atafb_setup(option);
#endif
	printk("atafb_init: start\n");

	if (!MACH_IS_ATARI)
		return -ENXIO;

	do {
#ifdef ATAFB_EXT
		if (external_addr) {
			printk("atafb_init: initializing external hw\n");
			fbhw = &ext_switch;
			atafb_ops.fb_setcolreg = &ext_setcolreg;
			defmode = DEFMODE_EXT;
			break;
		}
#endif
#ifdef ATAFB_TT
		if (ATARIHW_PRESENT(TT_SHIFTER)) {
			printk("atafb_init: initializing TT hw\n");
			fbhw = &tt_switch;
			atafb_ops.fb_setcolreg = &tt_setcolreg;
			defmode = DEFMODE_TT;
			break;
		}
#endif
#ifdef ATAFB_FALCON
		if (ATARIHW_PRESENT(VIDEL_SHIFTER)) {
			printk("atafb_init: initializing Falcon hw\n");
			fbhw = &falcon_switch;
			atafb_ops.fb_setcolreg = &falcon_setcolreg;
			request_irq(IRQ_AUTO_4, falcon_vbl_switcher, IRQ_TYPE_PRIO,
			            "framebuffer/modeswitch", falcon_vbl_switcher);
			defmode = DEFMODE_F30;
			break;
		}
#endif
#ifdef ATAFB_STE
		if (ATARIHW_PRESENT(STND_SHIFTER) ||
		    ATARIHW_PRESENT(EXTD_SHIFTER)) {
			printk("atafb_init: initializing ST/E hw\n");
			fbhw = &st_switch;
			atafb_ops.fb_setcolreg = &stste_setcolreg;
			defmode = DEFMODE_STE;
			break;
		}
		fbhw = &st_switch;
		atafb_ops.fb_setcolreg = &stste_setcolreg;
		printk("Cannot determine video hardware; defaulting to ST(e)\n");
#else /* ATAFB_STE */
		/* no default driver included */
		/* Nobody will ever see this message :-) */
		panic("Cannot initialize video hardware");
#endif
	} while (0);

	/* Multisync monitor capabilities */
	/* Atari-TOS defaults if no boot option present */
	if (fb_info.monspecs.hfmin == 0) {
		fb_info.monspecs.hfmin = 31000;
		fb_info.monspecs.hfmax = 32000;
		fb_info.monspecs.vfmin = 58;
		fb_info.monspecs.vfmax = 62;
	}

	detected_mode = fbhw->detect();
	check_default_par(detected_mode);
#ifdef ATAFB_EXT
	if (!external_addr) {
#endif /* ATAFB_EXT */
		mem_req = default_mem_req + ovsc_offset + ovsc_addlen;
		mem_req = PAGE_ALIGN(mem_req) + PAGE_SIZE;
		screen_base = atari_stram_alloc(mem_req, "atafb");
		if (!screen_base)
			panic("Cannot allocate screen memory");
		memset(screen_base, 0, mem_req);
		pad = -(unsigned long)screen_base & (PAGE_SIZE - 1);
		screen_base += pad;
		real_screen_base = screen_base + ovsc_offset;
		screen_len = (mem_req - pad - ovsc_offset) & PAGE_MASK;
		st_ovsc_switch();
		if (CPU_IS_040_OR_060) {
			/* On a '040+, the cache mode of video RAM must be set to
			 * write-through also for internal video hardware! */
			cache_push(virt_to_phys(screen_base), screen_len);
			kernel_set_cachemode(screen_base, screen_len,
					     IOMAP_WRITETHROUGH);
		}
		printk("atafb: screen_base %p real_screen_base %p screen_len %d\n",
			screen_base, real_screen_base, screen_len);
#ifdef ATAFB_EXT
	} else {
		/* Map the video memory (physical address given) to somewhere
		 * in the kernel address space.
		 */
		external_addr = ioremap_writethrough((unsigned long)external_addr,
						     external_len);
		if (external_vgaiobase)
			external_vgaiobase =
			  (unsigned long)ioremap(external_vgaiobase, 0x10000);
		screen_base =
		real_screen_base = external_addr;
		screen_len = external_len & PAGE_MASK;
		memset (screen_base, 0, external_len);
	}
#endif /* ATAFB_EXT */

//	strcpy(fb_info.mode->name, "Atari Builtin ");
	fb_info.fbops = &atafb_ops;
	// try to set default (detected; requested) var
	do_fb_set_var(&atafb_predefined[default_par - 1], 1);
	// reads hw state into current par, which may not be sane yet
	ata_get_par(&current_par);
	fb_info.par = &current_par;
	// tries to read from HW which may not be initialized yet
	// so set sane var first, then call atafb_set_par
	atafb_get_var(&fb_info.var, &fb_info);
	fb_info.flags = FBINFO_FLAG_DEFAULT;

	if (!fb_find_mode(&fb_info.var, &fb_info, mode_option, atafb_modedb,
			  NUM_TOTAL_MODES, &atafb_modedb[defmode],
			  fb_info.var.bits_per_pixel)) {
		return -EINVAL;
	}

	atafb_set_disp(&fb_info);

	fb_alloc_cmap(&(fb_info.cmap), 1 << fb_info.var.bits_per_pixel, 0);


	printk("Determined %dx%d, depth %d\n",
	       fb_info.var.xres, fb_info.var.yres, fb_info.var.bits_per_pixel);
	if ((fb_info.var.xres != fb_info.var.xres_virtual) ||
	    (fb_info.var.yres != fb_info.var.yres_virtual))
		printk("   virtual %dx%d\n", fb_info.var.xres_virtual,
		       fb_info.var.yres_virtual);

	if (register_framebuffer(&fb_info) < 0) {
#ifdef ATAFB_EXT
		if (external_addr) {
			iounmap(external_addr);
			external_addr = NULL;
		}
		if (external_vgaiobase) {
			iounmap((void*)external_vgaiobase);
			external_vgaiobase = 0;
		}
#endif
		return -EINVAL;
	}

	// FIXME: mode needs setting!
	//printk("fb%d: %s frame buffer device, using %dK of video memory\n",
	//       fb_info.node, fb_info.mode->name, screen_len>>10);
	printk("fb%d: frame buffer device, using %dK of video memory\n",
	       fb_info.node, screen_len >> 10);

	/* TODO: This driver cannot be unloaded yet */
	return 0;
}

module_init(atafb_init);

#ifdef MODULE
MODULE_LICENSE("GPL");

int cleanup_module(void)
{
	unregister_framebuffer(&fb_info);
	return atafb_deinit();
}
#endif /* MODULE */