[deliverable/linux.git] / drivers / video / console / fbcon.c

/*
 *  linux/drivers/video/fbcon.c -- Low level frame buffer based console driver
 *
 *	Copyright (C) 1995 Geert Uytterhoeven
 *
 *
 *  This file is based on the original Amiga console driver (amicon.c):
 *
 *	Copyright (C) 1993 Hamish Macdonald
 *			   Greg Harp
 *	Copyright (C) 1994 David Carter [carter@compsci.bristol.ac.uk]
 *
 *	      with work by William Rucklidge (wjr@cs.cornell.edu)
 *			   Geert Uytterhoeven
 *			   Jes Sorensen (jds@kom.auc.dk)
 *			   Martin Apel
 *
 *  and on the original Atari console driver (atacon.c):
 *
 *	Copyright (C) 1993 Bjoern Brauel
 *			   Roman Hodek
 *
 *	      with work by Guenther Kelleter
 *			   Martin Schaller
 *			   Andreas Schwab
 *
 *  Hardware cursor support added by Emmanuel Marty (core@ggi-project.org)
 *  Smart redraw scrolling, arbitrary font width support, 512char font support
 *  and software scrollback added by 
 *                         Jakub Jelinek (jj@ultra.linux.cz)
 *
 *  Random hacking by Martin Mares <mj@ucw.cz>
 *
 *	2001 - Documented with DocBook
 *	- Brad Douglas <brad@neruo.com>
 *
 *  The low level operations for the various display memory organizations are
 *  now in separate source files.
 *
 *  Currently the following organizations are supported:
 *
 *    o afb			Amiga bitplanes
 *    o cfb{2,4,8,16,24,32}	Packed pixels
 *    o ilbm			Amiga interleaved bitplanes
 *    o iplan2p[248]		Atari interleaved bitplanes
 *    o mfb			Monochrome
 *    o vga			VGA characters/attributes
 *
 *  To do:
 *
 *    - Implement 16 plane mode (iplan2p16)
 *
 *
 *  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.
 */

#undef FBCONDEBUG

#include <linux/module.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/delay.h>	/* MSch: for IRQ probe */
#include <linux/console.h>
#include <linux/string.h>
#include <linux/kd.h>
#include <linux/slab.h>
#include <linux/fb.h>
#include <linux/vt_kern.h>
#include <linux/selection.h>
#include <linux/font.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/crc32.h> /* For counting font checksums */
#include <asm/fb.h>
#include <asm/irq.h>

#include "fbcon.h"

#ifdef FBCONDEBUG
#  define DPRINTK(fmt, args...) printk(KERN_DEBUG "%s: " fmt, __func__ , ## args)
#else
#  define DPRINTK(fmt, args...)
#endif

enum {
	FBCON_LOGO_CANSHOW	= -1,	/* the logo can be shown */
	FBCON_LOGO_DRAW		= -2,	/* draw the logo to a console */
	FBCON_LOGO_DONTSHOW	= -3	/* do not show the logo */
};

static struct display fb_display[MAX_NR_CONSOLES];

static signed char con2fb_map[MAX_NR_CONSOLES];
static signed char con2fb_map_boot[MAX_NR_CONSOLES];

static int logo_lines;
/* logo_shown is an index to vc_cons when >= 0; otherwise follows FBCON_LOGO
   enums.  */
static int logo_shown = FBCON_LOGO_CANSHOW;
/* Software scrollback */
static int fbcon_softback_size = 32768;
static unsigned long softback_buf, softback_curr;
static unsigned long softback_in;
static unsigned long softback_top, softback_end;
static int softback_lines;
/* console mappings */
static int first_fb_vc;
static int last_fb_vc = MAX_NR_CONSOLES - 1;
static int fbcon_is_default = 1; 
static int fbcon_has_exited;
static int primary_device = -1;
static int fbcon_has_console_bind;

#ifdef CONFIG_FRAMEBUFFER_CONSOLE_DETECT_PRIMARY
static int map_override;

static inline void fbcon_map_override(void)
{
	map_override = 1;
}
#else
static inline void fbcon_map_override(void)
{
}
#endif /* CONFIG_FRAMEBUFFER_CONSOLE_DETECT_PRIMARY */

/* font data */
static char fontname[40];

/* current fb_info */
static int info_idx = -1;

/* console rotation */
static int initial_rotation;
static int fbcon_has_sysfs;

static const struct consw fb_con;

#define CM_SOFTBACK	(8)

#define advance_row(p, delta) (unsigned short *)((unsigned long)(p) + (delta) * vc->vc_size_row)

static int fbcon_set_origin(struct vc_data *);

#define CURSOR_DRAW_DELAY		(1)

static int vbl_cursor_cnt;
static int fbcon_cursor_noblink;

#define divides(a, b)	((!(a) || (b)%(a)) ? 0 : 1)

/*
 *  Interface used by the world
 */

static const char *fbcon_startup(void);
static void fbcon_init(struct vc_data *vc, int init);
static void fbcon_deinit(struct vc_data *vc);
static void fbcon_clear(struct vc_data *vc, int sy, int sx, int height,
			int width);
static void fbcon_putc(struct vc_data *vc, int c, int ypos, int xpos);
static void fbcon_putcs(struct vc_data *vc, const unsigned short *s,
			int count, int ypos, int xpos);
static void fbcon_clear_margins(struct vc_data *vc, int bottom_only);
static void fbcon_cursor(struct vc_data *vc, int mode);
static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
			int count);
static void fbcon_bmove(struct vc_data *vc, int sy, int sx, int dy, int dx,
			int height, int width);
static int fbcon_switch(struct vc_data *vc);
static int fbcon_blank(struct vc_data *vc, int blank, int mode_switch);
static int fbcon_set_palette(struct vc_data *vc, unsigned char *table);
static int fbcon_scrolldelta(struct vc_data *vc, int lines);

/*
 *  Internal routines
 */
static __inline__ void ywrap_up(struct vc_data *vc, int count);
static __inline__ void ywrap_down(struct vc_data *vc, int count);
static __inline__ void ypan_up(struct vc_data *vc, int count);
static __inline__ void ypan_down(struct vc_data *vc, int count);
static void fbcon_bmove_rec(struct vc_data *vc, struct display *p, int sy, int sx,
			    int dy, int dx, int height, int width, u_int y_break);
static void fbcon_set_disp(struct fb_info *info, struct fb_var_screeninfo *var,
			   int unit);
static void fbcon_redraw_move(struct vc_data *vc, struct display *p,
			      int line, int count, int dy);
static void fbcon_modechanged(struct fb_info *info);
static void fbcon_set_all_vcs(struct fb_info *info);
static void fbcon_start(void);
static void fbcon_exit(void);
static struct device *fbcon_device;

#ifdef CONFIG_FRAMEBUFFER_CONSOLE_ROTATION
static inline void fbcon_set_rotation(struct fb_info *info)
{
	struct fbcon_ops *ops = info->fbcon_par;

	if (!(info->flags & FBINFO_MISC_TILEBLITTING) &&
	    ops->p->con_rotate < 4)
		ops->rotate = ops->p->con_rotate;
	else
		ops->rotate = 0;
}

static void fbcon_rotate(struct fb_info *info, u32 rotate)
{
	struct fbcon_ops *ops= info->fbcon_par;
	struct fb_info *fb_info;

	if (!ops || ops->currcon == -1)
		return;

	fb_info = registered_fb[con2fb_map[ops->currcon]];

	if (info == fb_info) {
		struct display *p = &fb_display[ops->currcon];

		if (rotate < 4)
			p->con_rotate = rotate;
		else
			p->con_rotate = 0;

		fbcon_modechanged(info);
	}
}

static void fbcon_rotate_all(struct fb_info *info, u32 rotate)
{
	struct fbcon_ops *ops = info->fbcon_par;
	struct vc_data *vc;
	struct display *p;
	int i;

	if (!ops || ops->currcon < 0 || rotate > 3)
		return;

	for (i = first_fb_vc; i <= last_fb_vc; i++) {
		vc = vc_cons[i].d;
		if (!vc || vc->vc_mode != KD_TEXT ||
		    registered_fb[con2fb_map[i]] != info)
			continue;

		p = &fb_display[vc->vc_num];
		p->con_rotate = rotate;
	}

	fbcon_set_all_vcs(info);
}
#else
static inline void fbcon_set_rotation(struct fb_info *info)
{
	struct fbcon_ops *ops = info->fbcon_par;

	ops->rotate = FB_ROTATE_UR;
}

static void fbcon_rotate(struct fb_info *info, u32 rotate)
{
	return;
}

static void fbcon_rotate_all(struct fb_info *info, u32 rotate)
{
	return;
}
#endif /* CONFIG_FRAMEBUFFER_CONSOLE_ROTATION */

static int fbcon_get_rotate(struct fb_info *info)
{
	struct fbcon_ops *ops = info->fbcon_par;

	return (ops) ? ops->rotate : 0;
}

static inline int fbcon_is_inactive(struct vc_data *vc, struct fb_info *info)
{
	struct fbcon_ops *ops = info->fbcon_par;

	return (info->state != FBINFO_STATE_RUNNING ||
		vc->vc_mode != KD_TEXT || ops->graphics) &&
		!vt_force_oops_output(vc);
}

static int get_color(struct vc_data *vc, struct fb_info *info,
	      u16 c, int is_fg)
{
	int depth = fb_get_color_depth(&info->var, &info->fix);
	int color = 0;

	if (console_blanked) {
		unsigned short charmask = vc->vc_hi_font_mask ? 0x1ff : 0xff;

		c = vc->vc_video_erase_char & charmask;
	}

	if (depth != 1)
		color = (is_fg) ? attr_fgcol((vc->vc_hi_font_mask) ? 9 : 8, c)
			: attr_bgcol((vc->vc_hi_font_mask) ? 13 : 12, c);

	switch (depth) {
	case 1:
	{
		int col = mono_col(info);
		/* 0 or 1 */
		int fg = (info->fix.visual != FB_VISUAL_MONO01) ? col : 0;
		int bg = (info->fix.visual != FB_VISUAL_MONO01) ? 0 : col;

		if (console_blanked)
			fg = bg;

		color = (is_fg) ? fg : bg;
		break;
	}
	case 2:
		/*
		 * Scale down 16-colors to 4 colors. Default 4-color palette
		 * is grayscale. However, simply dividing the values by 4
		 * will not work, as colors 1, 2 and 3 will be scaled-down
		 * to zero rendering them invisible.  So empirically convert
		 * colors to a sane 4-level grayscale.
		 */
		switch (color) {
		case 0:
			color = 0; /* black */
			break;
		case 1 ... 6:
			color = 2; /* white */
			break;
		case 7 ... 8:
			color = 1; /* gray */
			break;
		default:
			color = 3; /* intense white */
			break;
		}
		break;
	case 3:
		/*
		 * Last 8 entries of default 16-color palette is a more intense
		 * version of the first 8 (i.e., same chrominance, different
		 * luminance).
		 */
		color &= 7;
		break;
	}


	return color;
}

static void fbcon_update_softback(struct vc_data *vc)
{
	int l = fbcon_softback_size / vc->vc_size_row;

	if (l > 5)
		softback_end = softback_buf + l * vc->vc_size_row;
	else
		/* Smaller scrollback makes no sense, and 0 would screw
		   the operation totally */
		softback_top = 0;
}

static void fb_flashcursor(struct work_struct *work)
{
	struct fb_info *info = container_of(work, struct fb_info, queue);
	struct fbcon_ops *ops = info->fbcon_par;
	struct vc_data *vc = NULL;
	int c;
	int mode;

	console_lock();
	if (ops && ops->currcon != -1)
		vc = vc_cons[ops->currcon].d;

	if (!vc || !CON_IS_VISIBLE(vc) ||
 	    registered_fb[con2fb_map[vc->vc_num]] != info ||
	    vc->vc_deccm != 1) {
		console_unlock();
		return;
	}

	c = scr_readw((u16 *) vc->vc_pos);
	mode = (!ops->cursor_flash || ops->cursor_state.enable) ?
		CM_ERASE : CM_DRAW;
	ops->cursor(vc, info, mode, softback_lines, get_color(vc, info, c, 1),
		    get_color(vc, info, c, 0));
	console_unlock();
}

static void cursor_timer_handler(unsigned long dev_addr)
{
	struct fb_info *info = (struct fb_info *) dev_addr;
	struct fbcon_ops *ops = info->fbcon_par;

	schedule_work(&info->queue);
	mod_timer(&ops->cursor_timer, jiffies + HZ/5);
}

static void fbcon_add_cursor_timer(struct fb_info *info)
{
	struct fbcon_ops *ops = info->fbcon_par;

	if ((!info->queue.func || info->queue.func == fb_flashcursor) &&
	    !(ops->flags & FBCON_FLAGS_CURSOR_TIMER) &&
	    !fbcon_cursor_noblink) {
		if (!info->queue.func)
			INIT_WORK(&info->queue, fb_flashcursor);

		init_timer(&ops->cursor_timer);
		ops->cursor_timer.function = cursor_timer_handler;
		ops->cursor_timer.expires = jiffies + HZ / 5;
		ops->cursor_timer.data = (unsigned long ) info;
		add_timer(&ops->cursor_timer);
		ops->flags |= FBCON_FLAGS_CURSOR_TIMER;
	}
}

static void fbcon_del_cursor_timer(struct fb_info *info)
{
	struct fbcon_ops *ops = info->fbcon_par;

	if (info->queue.func == fb_flashcursor &&
	    ops->flags & FBCON_FLAGS_CURSOR_TIMER) {
		del_timer_sync(&ops->cursor_timer);
		ops->flags &= ~FBCON_FLAGS_CURSOR_TIMER;
	}
}

#ifndef MODULE
static int __init fb_console_setup(char *this_opt)
{
	char *options;
	int i, j;

	if (!this_opt || !*this_opt)
		return 1;

	while ((options = strsep(&this_opt, ",")) != NULL) {
		if (!strncmp(options, "font:", 5))
			strcpy(fontname, options + 5);
		
		if (!strncmp(options, "scrollback:", 11)) {
			options += 11;
			if (*options) {
				fbcon_softback_size = simple_strtoul(options, &options, 0);
				if (*options == 'k' || *options == 'K') {
					fbcon_softback_size *= 1024;
					options++;
				}
				if (*options != ',')
					return 1;
				options++;
			} else
				return 1;
		}
		
		if (!strncmp(options, "map:", 4)) {
			options += 4;
			if (*options) {
				for (i = 0, j = 0; i < MAX_NR_CONSOLES; i++) {
					if (!options[j])
						j = 0;
					con2fb_map_boot[i] =
						(options[j++]-'0') % FB_MAX;
				}

				fbcon_map_override();
			}

			return 1;
		}

		if (!strncmp(options, "vc:", 3)) {
			options += 3;
			if (*options)
				first_fb_vc = simple_strtoul(options, &options, 10) - 1;
			if (first_fb_vc < 0)
				first_fb_vc = 0;
			if (*options++ == '-')
				last_fb_vc = simple_strtoul(options, &options, 10) - 1;
			fbcon_is_default = 0; 
		}	

		if (!strncmp(options, "rotate:", 7)) {
			options += 7;
			if (*options)
				initial_rotation = simple_strtoul(options, &options, 0);
			if (initial_rotation > 3)
				initial_rotation = 0;
		}
	}
	return 1;
}

__setup("fbcon=", fb_console_setup);
#endif

static int search_fb_in_map(int idx)
{
	int i, retval = 0;

	for (i = first_fb_vc; i <= last_fb_vc; i++) {
		if (con2fb_map[i] == idx)
			retval = 1;
	}
	return retval;
}

static int search_for_mapped_con(void)
{
	int i, retval = 0;

	for (i = first_fb_vc; i <= last_fb_vc; i++) {
		if (con2fb_map[i] != -1)
			retval = 1;
	}
	return retval;
}

static int fbcon_takeover(int show_logo)
{
	int err, i;

	if (!num_registered_fb)
		return -ENODEV;

	if (!show_logo)
		logo_shown = FBCON_LOGO_DONTSHOW;

	for (i = first_fb_vc; i <= last_fb_vc; i++)
		con2fb_map[i] = info_idx;

	err = take_over_console(&fb_con, first_fb_vc, last_fb_vc,
				fbcon_is_default);

	if (err) {
		for (i = first_fb_vc; i <= last_fb_vc; i++) {
			con2fb_map[i] = -1;
		}
		info_idx = -1;
	} else {
		fbcon_has_console_bind = 1;
	}

	return err;
}

#ifdef MODULE
static void fbcon_prepare_logo(struct vc_data *vc, struct fb_info *info,
			       int cols, int rows, int new_cols, int new_rows)
{
	logo_shown = FBCON_LOGO_DONTSHOW;
}
#else
static void fbcon_prepare_logo(struct vc_data *vc, struct fb_info *info,
			       int cols, int rows, int new_cols, int new_rows)
{
	/* Need to make room for the logo */
	struct fbcon_ops *ops = info->fbcon_par;
	int cnt, erase = vc->vc_video_erase_char, step;
	unsigned short *save = NULL, *r, *q;
	int logo_height;

	if (info->flags & FBINFO_MODULE) {
		logo_shown = FBCON_LOGO_DONTSHOW;
		return;
	}

	/*
	 * remove underline attribute from erase character
	 * if black and white framebuffer.
	 */
	if (fb_get_color_depth(&info->var, &info->fix) == 1)
		erase &= ~0x400;
	logo_height = fb_prepare_logo(info, ops->rotate);
	logo_lines = DIV_ROUND_UP(logo_height, vc->vc_font.height);
	q = (unsigned short *) (vc->vc_origin +
				vc->vc_size_row * rows);
	step = logo_lines * cols;
	for (r = q - logo_lines * cols; r < q; r++)
		if (scr_readw(r) != vc->vc_video_erase_char)
			break;
	if (r != q && new_rows >= rows + logo_lines) {
		save = kmalloc(logo_lines * new_cols * 2, GFP_KERNEL);
		if (save) {
			int i = cols < new_cols ? cols : new_cols;
			scr_memsetw(save, erase, logo_lines * new_cols * 2);
			r = q - step;
			for (cnt = 0; cnt < logo_lines; cnt++, r += i)
				scr_memcpyw(save + cnt * new_cols, r, 2 * i);
			r = q;
		}
	}
	if (r == q) {
		/* We can scroll screen down */
		r = q - step - cols;
		for (cnt = rows - logo_lines; cnt > 0; cnt--) {
			scr_memcpyw(r + step, r, vc->vc_size_row);
			r -= cols;
		}
		if (!save) {
			int lines;
			if (vc->vc_y + logo_lines >= rows)
				lines = rows - vc->vc_y - 1;
			else
				lines = logo_lines;
			vc->vc_y += lines;
			vc->vc_pos += lines * vc->vc_size_row;
		}
	}
	scr_memsetw((unsigned short *) vc->vc_origin,
		    erase,
		    vc->vc_size_row * logo_lines);

	if (CON_IS_VISIBLE(vc) && vc->vc_mode == KD_TEXT) {
		fbcon_clear_margins(vc, 0);
		update_screen(vc);
	}

	if (save) {
		q = (unsigned short *) (vc->vc_origin +
					vc->vc_size_row *
					rows);
		scr_memcpyw(q, save, logo_lines * new_cols * 2);
		vc->vc_y += logo_lines;
		vc->vc_pos += logo_lines * vc->vc_size_row;
		kfree(save);
	}

	if (logo_lines > vc->vc_bottom) {
		logo_shown = FBCON_LOGO_CANSHOW;
		printk(KERN_INFO
		       "fbcon_init: disable boot-logo (boot-logo bigger than screen).\n");
	} else if (logo_shown != FBCON_LOGO_DONTSHOW) {
		logo_shown = FBCON_LOGO_DRAW;
		vc->vc_top = logo_lines;
	}
}
#endif /* MODULE */

#ifdef CONFIG_FB_TILEBLITTING
static void set_blitting_type(struct vc_data *vc, struct fb_info *info)
{
	struct fbcon_ops *ops = info->fbcon_par;

	ops->p = &fb_display[vc->vc_num];

	if ((info->flags & FBINFO_MISC_TILEBLITTING))
		fbcon_set_tileops(vc, info);
	else {
		fbcon_set_rotation(info);
		fbcon_set_bitops(ops);
	}
}

static int fbcon_invalid_charcount(struct fb_info *info, unsigned charcount)
{
	int err = 0;

	if (info->flags & FBINFO_MISC_TILEBLITTING &&
	    info->tileops->fb_get_tilemax(info) < charcount)
		err = 1;

	return err;
}
#else
static void set_blitting_type(struct vc_data *vc, struct fb_info *info)
{
	struct fbcon_ops *ops = info->fbcon_par;

	info->flags &= ~FBINFO_MISC_TILEBLITTING;
	ops->p = &fb_display[vc->vc_num];
	fbcon_set_rotation(info);
	fbcon_set_bitops(ops);
}

static int fbcon_invalid_charcount(struct fb_info *info, unsigned charcount)
{
	return 0;
}

#endif /* CONFIG_MISC_TILEBLITTING */


static int con2fb_acquire_newinfo(struct vc_data *vc, struct fb_info *info,
				  int unit, int oldidx)
{
	struct fbcon_ops *ops = NULL;
	int err = 0;

	if (!try_module_get(info->fbops->owner))
		err = -ENODEV;

	if (!err && info->fbops->fb_open &&
	    info->fbops->fb_open(info, 0))
		err = -ENODEV;

	if (!err) {
		ops = kzalloc(sizeof(struct fbcon_ops), GFP_KERNEL);
		if (!ops)
			err = -ENOMEM;
	}

	if (!err) {
		info->fbcon_par = ops;

		if (vc)
			set_blitting_type(vc, info);
	}

	if (err) {
		con2fb_map[unit] = oldidx;
		module_put(info->fbops->owner);
	}

	return err;
}

static int con2fb_release_oldinfo(struct vc_data *vc, struct fb_info *oldinfo,
				  struct fb_info *newinfo, int unit,
				  int oldidx, int found)
{
	struct fbcon_ops *ops = oldinfo->fbcon_par;
	int err = 0, ret;

	if (oldinfo->fbops->fb_release &&
	    oldinfo->fbops->fb_release(oldinfo, 0)) {
		con2fb_map[unit] = oldidx;
		if (!found && newinfo->fbops->fb_release)
			newinfo->fbops->fb_release(newinfo, 0);
		if (!found)
			module_put(newinfo->fbops->owner);
		err = -ENODEV;
	}

	if (!err) {
		fbcon_del_cursor_timer(oldinfo);
		kfree(ops->cursor_state.mask);
		kfree(ops->cursor_data);
		kfree(ops->fontbuffer);
		kfree(oldinfo->fbcon_par);
		oldinfo->fbcon_par = NULL;
		module_put(oldinfo->fbops->owner);
		/*
		  If oldinfo and newinfo are driving the same hardware,
		  the fb_release() method of oldinfo may attempt to
		  restore the hardware state.  This will leave the
		  newinfo in an undefined state. Thus, a call to
		  fb_set_par() may be needed for the newinfo.
		*/
		if (newinfo->fbops->fb_set_par) {
			ret = newinfo->fbops->fb_set_par(newinfo);

			if (ret)
				printk(KERN_ERR "con2fb_release_oldinfo: "
					"detected unhandled fb_set_par error, "
					"error code %d\n", ret);
		}
	}

	return err;
}

static void con2fb_init_display(struct vc_data *vc, struct fb_info *info,
				int unit, int show_logo)
{
	struct fbcon_ops *ops = info->fbcon_par;
	int ret;

	ops->currcon = fg_console;

	if (info->fbops->fb_set_par && !(ops->flags & FBCON_FLAGS_INIT)) {
		ret = info->fbops->fb_set_par(info);

		if (ret)
			printk(KERN_ERR "con2fb_init_display: detected "
				"unhandled fb_set_par error, "
				"error code %d\n", ret);
	}

	ops->flags |= FBCON_FLAGS_INIT;
	ops->graphics = 0;
	fbcon_set_disp(info, &info->var, unit);

	if (show_logo) {
		struct vc_data *fg_vc = vc_cons[fg_console].d;
		struct fb_info *fg_info =
			registered_fb[con2fb_map[fg_console]];

		fbcon_prepare_logo(fg_vc, fg_info, fg_vc->vc_cols,
				   fg_vc->vc_rows, fg_vc->vc_cols,
				   fg_vc->vc_rows);
	}

	update_screen(vc_cons[fg_console].d);
}

/**
 *	set_con2fb_map - map console to frame buffer device
 *	@unit: virtual console number to map
 *	@newidx: frame buffer index to map virtual console to
 *      @user: user request
 *
 *	Maps a virtual console @unit to a frame buffer device
 *	@newidx.
 */
static int set_con2fb_map(int unit, int newidx, int user)
{
	struct vc_data *vc = vc_cons[unit].d;
	int oldidx = con2fb_map[unit];
	struct fb_info *info = registered_fb[newidx];
	struct fb_info *oldinfo = NULL;
 	int found, err = 0;

	if (oldidx == newidx)
		return 0;

	if (!info)
		return -EINVAL;

	if (!search_for_mapped_con() || !con_is_bound(&fb_con)) {
		info_idx = newidx;
		return fbcon_takeover(0);
	}

	if (oldidx != -1)
		oldinfo = registered_fb[oldidx];

	found = search_fb_in_map(newidx);

	console_lock();
	con2fb_map[unit] = newidx;
	if (!err && !found)
 		err = con2fb_acquire_newinfo(vc, info, unit, oldidx);


	/*
	 * If old fb is not mapped to any of the consoles,
	 * fbcon should release it.
	 */
 	if (!err && oldinfo && !search_fb_in_map(oldidx))
 		err = con2fb_release_oldinfo(vc, oldinfo, info, unit, oldidx,
 					     found);

 	if (!err) {
 		int show_logo = (fg_console == 0 && !user &&
 				 logo_shown != FBCON_LOGO_DONTSHOW);

 		if (!found)
 			fbcon_add_cursor_timer(info);
 		con2fb_map_boot[unit] = newidx;
 		con2fb_init_display(vc, info, unit, show_logo);
	}

	if (!search_fb_in_map(info_idx))
		info_idx = newidx;

	console_unlock();
 	return err;
}

/*
 *  Low Level Operations
 */
/* NOTE: fbcon cannot be __init: it may be called from take_over_console later */
static int var_to_display(struct display *disp,
			  struct fb_var_screeninfo *var,
			  struct fb_info *info)
{
	disp->xres_virtual = var->xres_virtual;
	disp->yres_virtual = var->yres_virtual;
	disp->bits_per_pixel = var->bits_per_pixel;
	disp->grayscale = var->grayscale;
	disp->nonstd = var->nonstd;
	disp->accel_flags = var->accel_flags;
	disp->height = var->height;
	disp->width = var->width;
	disp->red = var->red;
	disp->green = var->green;
	disp->blue = var->blue;
	disp->transp = var->transp;
	disp->rotate = var->rotate;
	disp->mode = fb_match_mode(var, &info->modelist);
	if (disp->mode == NULL)
		/* This should not happen */
		return -EINVAL;
	return 0;
}

static void display_to_var(struct fb_var_screeninfo *var,
			   struct display *disp)
{
	fb_videomode_to_var(var, disp->mode);
	var->xres_virtual = disp->xres_virtual;
	var->yres_virtual = disp->yres_virtual;
	var->bits_per_pixel = disp->bits_per_pixel;
	var->grayscale = disp->grayscale;
	var->nonstd = disp->nonstd;
	var->accel_flags = disp->accel_flags;
	var->height = disp->height;
	var->width = disp->width;
	var->red = disp->red;
	var->green = disp->green;
	var->blue = disp->blue;
	var->transp = disp->transp;
	var->rotate = disp->rotate;
}

static const char *fbcon_startup(void)
{
	const char *display_desc = "frame buffer device";
	struct display *p = &fb_display[fg_console];
	struct vc_data *vc = vc_cons[fg_console].d;
	const struct font_desc *font = NULL;
	struct module *owner;
	struct fb_info *info = NULL;
	struct fbcon_ops *ops;
	int rows, cols;

	/*
	 *  If num_registered_fb is zero, this is a call for the dummy part.
	 *  The frame buffer devices weren't initialized yet.
	 */
	if (!num_registered_fb || info_idx == -1)
		return display_desc;
	/*
	 * Instead of blindly using registered_fb[0], we use info_idx, set by
	 * fb_console_init();
	 */
	info = registered_fb[info_idx];
	if (!info)
		return NULL;
	
	owner = info->fbops->owner;
	if (!try_module_get(owner))
		return NULL;
	if (info->fbops->fb_open && info->fbops->fb_open(info, 0)) {
		module_put(owner);
		return NULL;
	}

	ops = kzalloc(sizeof(struct fbcon_ops), GFP_KERNEL);
	if (!ops) {
		module_put(owner);
		return NULL;
	}

	ops->currcon = -1;
	ops->graphics = 1;
	ops->cur_rotate = -1;
	info->fbcon_par = ops;
	p->con_rotate = initial_rotation;
	set_blitting_type(vc, info);

	if (info->fix.type != FB_TYPE_TEXT) {
		if (fbcon_softback_size) {
			if (!softback_buf) {
				softback_buf =
				    (unsigned long)
				    kmalloc(fbcon_softback_size,
					    GFP_KERNEL);
				if (!softback_buf) {
					fbcon_softback_size = 0;
					softback_top = 0;
				}
			}
		} else {
			if (softback_buf) {
				kfree((void *) softback_buf);
				softback_buf = 0;
				softback_top = 0;
			}
		}
		if (softback_buf)
			softback_in = softback_top = softback_curr =
			    softback_buf;
		softback_lines = 0;
	}

	/* Setup default font */
	if (!p->fontdata) {
		if (!fontname[0] || !(font = find_font(fontname)))
			font = get_default_font(info->var.xres,
						info->var.yres,
						info->pixmap.blit_x,
						info->pixmap.blit_y);
		vc->vc_font.width = font->width;
		vc->vc_font.height = font->height;
		vc->vc_font.data = (void *)(p->fontdata = font->data);
		vc->vc_font.charcount = 256; /* FIXME  Need to support more fonts */
	}

	cols = FBCON_SWAP(ops->rotate, info->var.xres, info->var.yres);
	rows = FBCON_SWAP(ops->rotate, info->var.yres, info->var.xres);
	cols /= vc->vc_font.width;
	rows /= vc->vc_font.height;
	vc_resize(vc, cols, rows);

	DPRINTK("mode:   %s\n", info->fix.id);
	DPRINTK("visual: %d\n", info->fix.visual);
	DPRINTK("res:    %dx%d-%d\n", info->var.xres,
		info->var.yres,
		info->var.bits_per_pixel);

	fbcon_add_cursor_timer(info);
	fbcon_has_exited = 0;
	return display_desc;
}

static void fbcon_init(struct vc_data *vc, int init)
{
	struct fb_info *info = registered_fb[con2fb_map[vc->vc_num]];
	struct fbcon_ops *ops;
	struct vc_data **default_mode = vc->vc_display_fg;
	struct vc_data *svc = *default_mode;
	struct display *t, *p = &fb_display[vc->vc_num];
	int logo = 1, new_rows, new_cols, rows, cols, charcnt = 256;
	int cap, ret;

	if (info_idx == -1 || info == NULL)
	    return;

	cap = info->flags;

	if (vc != svc || logo_shown == FBCON_LOGO_DONTSHOW ||
	    (info->fix.type == FB_TYPE_TEXT))
		logo = 0;

	if (var_to_display(p, &info->var, info))
		return;

	if (!info->fbcon_par)
		con2fb_acquire_newinfo(vc, info, vc->vc_num, -1);

	/* If we are not the first console on this
	   fb, copy the font from that console */
	t = &fb_display[fg_console];
	if (!p->fontdata) {
		if (t->fontdata) {
			struct vc_data *fvc = vc_cons[fg_console].d;

			vc->vc_font.data = (void *)(p->fontdata =
						    fvc->vc_font.data);
			vc->vc_font.width = fvc->vc_font.width;
			vc->vc_font.height = fvc->vc_font.height;
			p->userfont = t->userfont;

			if (p->userfont)
				REFCOUNT(p->fontdata)++;
		} else {
			const struct font_desc *font = NULL;

			if (!fontname[0] || !(font = find_font(fontname)))
				font = get_default_font(info->var.xres,
							info->var.yres,
							info->pixmap.blit_x,
							info->pixmap.blit_y);
			vc->vc_font.width = font->width;
			vc->vc_font.height = font->height;
			vc->vc_font.data = (void *)(p->fontdata = font->data);
			vc->vc_font.charcount = 256; /* FIXME  Need to
							support more fonts */
		}
	}

	if (p->userfont)
		charcnt = FNTCHARCNT(p->fontdata);

	vc->vc_panic_force_write = !!(info->flags & FBINFO_CAN_FORCE_OUTPUT);
	vc->vc_can_do_color = (fb_get_color_depth(&info->var, &info->fix)!=1);
	vc->vc_complement_mask = vc->vc_can_do_color ? 0x7700 : 0x0800;
	if (charcnt == 256) {
		vc->vc_hi_font_mask = 0;
	} else {
		vc->vc_hi_font_mask = 0x100;
		if (vc->vc_can_do_color)
			vc->vc_complement_mask <<= 1;
	}

	if (!*svc->vc_uni_pagedir_loc)
		con_set_default_unimap(svc);
	if (!*vc->vc_uni_pagedir_loc)
		con_copy_unimap(vc, svc);

	ops = info->fbcon_par;
	p->con_rotate = initial_rotation;
	set_blitting_type(vc, info);

	cols = vc->vc_cols;
	rows = vc->vc_rows;
	new_cols = FBCON_SWAP(ops->rotate, info->var.xres, info->var.yres);
	new_rows = FBCON_SWAP(ops->rotate, info->var.yres, info->var.xres);
	new_cols /= vc->vc_font.width;
	new_rows /= vc->vc_font.height;

	/*
	 * We must always set the mode. The mode of the previous console
	 * driver could be in the same resolution but we are using different
	 * hardware so we have to initialize the hardware.
	 *
	 * We need to do it in fbcon_init() to prevent screen corruption.
	 */