path: root/drivers/video/skeletonfb.c

/*
 * linux/drivers/video/skeletonfb.c -- Skeleton for a frame buffer device
 *
 *  Created 28 Dec 1997 by Geert Uytterhoeven
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive
 * for more details.
 */

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

#include <video/fbcon.h>


    /*
     *  This is just simple sample code.
     *
     *  No warranty that it actually compiles.
     *  Even less warranty that it actually works :-)
     */


struct xxxfb_info {
    /*
     *  Choose _one_ of the two alternatives:
     *
     *    1. Use the generic frame buffer operations (fbgen_*).
     */
    struct fb_info_gen gen;
    /*
     *    2. Provide your own frame buffer operations.
     */
    struct fb_info info;

    /* Here starts the frame buffer device dependent part */
    /* You can use this to store e.g. the board number if you support */
    /* multiple boards */
};


struct xxxfb_par {
    /*
     *  The hardware specific data in this structure uniquely defines a video
     *  mode.
     *
     *  If your hardware supports only one video mode, you can leave it empty.
     */
};


    /*
     *  If your driver supports multiple boards, you should make these arrays,
     *  or allocate them dynamically (using kmalloc()).
     */

static struct xxxfb_info fb_info;
static struct xxxfb_par current_par;
static int current_par_valid = 0;
static struct display disp;

static struct fb_var_screeninfo default_var;

static int currcon = 0;
static int inverse = 0;

int xxxfb_init(void);
int xxxfb_setup(char*);

/* ------------------- chipset specific functions -------------------------- */


static void xxx_detect(void)
{
    /*
     *  This function should detect the current video mode settings and store
     *  it as the default video mode
     */

    struct xxxfb_par par;

    /* ... */
    xxx_get_par(&par);
    xxx_encode_var(&default_var, &par);
}

static int xxx_encode_fix(struct fb_fix_screeninfo *fix, struct xxxfb_par *par,
			  const struct fb_info *info)
{
    /*
     *  This function should fill in the 'fix' structure based on the values
     *  in the `par' structure.
     */

    /* ... */
    return 0;
}

static int xxx_decode_var(struct fb_var_screeninfo *var, struct xxxfb_par *par,
			  const struct fb_info *info)
{
    /*
     *  Get the video params out of 'var'. If a value doesn't fit, round it up,
     *  if it's too big, return -EINVAL.
     *
     *  Suggestion: Round up in the following order: bits_per_pixel, xres,
     *  yres, xres_virtual, yres_virtual, xoffset, yoffset, grayscale,
     *  bitfields, horizontal timing, vertical timing.
     */

    /* ... */

    /* pixclock in picos, htotal in pixels, vtotal in scanlines */
    if (!fbmon_valid_timings(pixclock, htotal, vtotal, info))
	    return -EINVAL;

    return 0;
}

static int xxx_encode_var(struct fb_var_screeninfo *var, struct xxxfb_par *par,
			  const struct fb_info *info)
{
    /*
     *  Fill the 'var' structure based on the values in 'par' and maybe other
     *  values read out of the hardware.
     */

    /* ... */
    return 0;
}

static void xxx_get_par(struct xxxfb_par *par, const struct fb_info *info)
{
    /*
     *  Fill the hardware's 'par' structure.
     */

    if (current_par_valid)
	*par = current_par;
    else {
	/* ... */
    }
}

static void xxx_set_par(struct xxxfb_par *par, const struct fb_info *info)
{
    /*
     *  Set the hardware according to 'par'.
     */

    current_par = *par;
    current_par_valid = 1;
    /* ... */
}

static int xxx_getcolreg(unsigned regno, unsigned *red, unsigned *green,
			 unsigned *blue, unsigned *transp,
			 const struct fb_info *info)
{
    /*
     *  Read a single color register and split it into colors/transparent.
     *  The return values must have a 16 bit magnitude.
     *  Return != 0 for invalid regno.
     */

    /* ... */
    return 0;
}

static int xxx_setcolreg(unsigned regno, unsigned red, unsigned green,
			 unsigned blue, unsigned transp,
			 const struct fb_info *info)
{
    /*
     *  Set a single color register. The values supplied have a 16 bit
     *  magnitude.
     *  Return != 0 for invalid regno.
     */

    if (regno < 16) {
	/*
	 *  Make the first 16 colors of the palette available to fbcon
	 */
	if (is_cfb15)		/* RGB 555 */
	    ...fbcon_cmap.cfb16[regno] = ((red & 0xf800) >> 1) |
					 ((green & 0xf800) >> 6) |
					 ((blue & 0xf800) >> 11);
	if (is_cfb16)		/* RGB 565 */
	    ...fbcon_cmap.cfb16[regno] = (red & 0xf800) |
					 ((green & 0xfc00) >> 5) |
					 ((blue & 0xf800) >> 11);
	if (is_cfb24)		/* RGB 888 */
	    ...fbcon_cmap.cfb24[regno] = ((red & 0xff00) << 8) |
					 (green & 0xff00) |
					 ((blue & 0xff00) >> 8);
	if (is_cfb32)		/* RGBA 8888 */
	    ...fbcon_cmap.cfb32[regno] = ((red & 0xff00) << 16) |
					 ((green & 0xff00) << 8) |
					 (blue & 0xff00) |
					 ((transp & 0xff00) >> 8);
    }
    /* ... */
    return 0;
}

static int xxx_pan_display(struct fb_var_screeninfo *var,
			   struct xxxfb_par *par, const struct fb_info *info)
{
    /*
     *  Pan (or wrap, depending on the `vmode' field) the display using the
     *  `xoffset' and `yoffset' fields of the `var' structure.
     *  If the values don't fit, return -EINVAL.
     */

    /* ... */
    return 0;
}

static int xxx_blank(int blank_mode, const struct fb_info *info)
{
    /*
     *  Blank the screen if blank_mode != 0, else unblank. If blank == NULL
     *  then the caller blanks by setting the CLUT (Color Look Up Table) 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
     *    blank_mode == 3: suspend hsync
     *    blank_mode == 4: powerdown
     */

    /* ... */
    return 0;
}

static void xxx_set_disp(const void *par, struct display *disp,
			 struct fb_info_gen *info)
{
    /*
     *  Fill in a pointer with the virtual address of the mapped frame buffer.
     *  Fill in a pointer to appropriate low level text console operations (and
     *  optionally a pointer to help data) for the video mode `par' of your
     *  video hardware. These can be generic software routines, or hardware
     *  accelerated routines specifically tailored for your hardware.
     *  If you don't have any appropriate operations, you must fill in a
     *  pointer to dummy operations, and there will be no text output.
     */
    disp->screen_base = virtual_frame_buffer_address;
#ifdef FBCON_HAS_CFB8
    if (is_cfb8) {
	disp->dispsw = fbcon_cfb8;
    } else
#endif
#ifdef FBCON_HAS_CFB16
    if (is_cfb16) {
	disp->dispsw = fbcon_cfb16;
	disp->dispsw_data = ...fbcon_cmap.cfb16;	/* console palette */
    } else
#endif
#ifdef FBCON_HAS_CFB24
    if (is_cfb24) {
	disp->dispsw = fbcon_cfb24;
	disp->dispsw_data = ...fbcon_cmap.cfb24;	/* console palette */
    } else
#endif
#ifdef FBCON_HAS_CFB32
    if (is_cfb32) {
	disp->dispsw = fbcon_cfb32;
	disp->dispsw_data = ...fbcon_cmap.cfb32;	/* console palette */
    } else
#endif
	disp->dispsw = &fbcon_dummy;
}


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


struct fbgen_hwswitch xxx_switch = {
    xxx_detect, xxx_encode_fix, xxx_decode_var, xxx_encode_var, xxx_get_par,
    xxx_set_par, xxx_getcolreg, xxx_setcolreg, xxx_pan_display, xxx_blank,
    xxx_set_disp
};



/* ------------ Hardware Independent Functions ------------ */


    /*
     *  Initialization
     */

int __init xxxfb_init(void)
{
    fb_info.gen.fbhw = &xxx_switch;
    fb_info.gen.fbhw->detect();
    strcpy(fb_info.gen.info.modename, "XXX");
    fb_info.gen.info.changevar = NULL;
    fb_info.gen.info.node = -1;
    fb_info.gen.info.fbops = &xxxfb_ops;
    fb_info.gen.info.disp = &disp;
    fb_info.gen.info.switch_con = &xxxfb_switch;
    fb_info.gen.info.updatevar = &xxxfb_update_var;
    fb_info.gen.info.blank = &xxxfb_blank;
    fb_info.gen.info.flags = FBINFO_FLAG_DEFAULT;
    /* This should give a reasonable default video mode */
    fbgen_get_var(&disp.var, -1, &fb_info.gen.info);
    fbgen_do_set_var(&disp.var, 1, &fb_info.gen);
    fbgen_set_disp(-1, &fb_info.gen);
    fbgen_install_cmap(0, &fb_info.gen);
    if (register_framebuffer(&fb_info.gen.info) < 0)
	return -EINVAL;
    printk(KERN_INFO "fb%d: %s frame buffer device\n", GET_FB_IDX(fb_info.gen.info.node),
	   fb_info.gen.info.modename);

    /* uncomment this if your driver cannot be unloaded */
    /* MOD_INC_USE_COUNT; */
    return 0;
}


    /*
     *  Cleanup
     */

void xxxfb_cleanup(struct fb_info *info)
{
    /*
     *  If your driver supports multiple boards, you should unregister and
     *  clean up all instances.
     */

    unregister_framebuffer(info);
    /* ... */
}


    /*
     *  Setup
     */

int __init xxxfb_setup(char *options)
{
    /* Parse user speficied options (`video=xxxfb:') */
}


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


    /*
     *  Frame buffer operations
     */

/* If all you need is that - just don't define ->fb_open */
static int xxxfb_open(const struct fb_info *info, int user)
{
    return 0;
}

/* If all you need is that - just don't define ->fb_release */
static int xxxfb_release(const struct fb_info *info, int user)
{
    return 0;
}


    /*
     *  In most cases the `generic' routines (fbgen_*) should be satisfactory.
     *  However, you're free to fill in your own replacements.
     */

static struct fb_ops xxxfb_ops = {
	owner:		THIS_MODULE,
	fb_open:	xxxfb_open,    /* only if you need it to do something */
	fb_release:	xxxfb_release, /* only if you need it to do something */
	fb_get_fix:	fbgen_get_fix,
	fb_get_var:	fbgen_get_var,
	fb_set_var:	fbgen_set_var,
	fb_get_cmap:	fbgen_get_cmap,
	fb_set_cmap:	fbgen_set_cmap,
	fb_pan_display:	fbgen_pan_display,
	fb_ioctl:	xxxfb_ioctl,   /* optional */
};


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


    /*
     *  Modularization
     */

#ifdef MODULE
int init_module(void)
{
    return xxxfb_init();
}

void cleanup_module(void)
{
    xxxfb_cleanup(void);
}
#endif /* MODULE */