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[Linux-fbdev-devel] New API
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From: James S. <jsi...@tr...> - 2001-11-14 19:59:05
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Hi folks. I finally hammered a newer api for framebuffer devices. I
adapted skeletonfb.c to show it off. Feedback welcomed.
/*
* linux/drivers/video/skeletonfb.c -- Skeleton for a frame buffer device
*
* Modified to new api Jan 2001 by James Simmons (jsi...@tr...)
*
* Created 28 Dec 1997 by Geert Uytterhoeven
*
*
* I have started rewriting this driver as a example of the upcoming new API
* The primary goal is to remove the console code from fbdev and place it
* into fbcon.c. This reduces the code and makes writing a new fbdev driver
* easy since the author doesn't need to worry about console internals. It
* also allows the ability to run fbdev without a console system on top of it.
*
* First the roles of struct fb_info and struct display have changed. Struct
* display has gone away. The upper framebuffer console layer only depends on
* fb_info. For each framebuffer device when used as a VT console is allocate
* a set of virtual terminals to it. Only one virtual terminal can be active
* per framebuffer device. So I have struct fb_info represent all the data of
* the current hardware state of the framebuffer. Meaning the resolution of
* the active VT (the one you're looking at) and other data is stored in the
* fb_info struct. When you VT switch the current video state is translated
* to a form to be stored by the the higher level console layer to be stored
* for that terminal you just switched away from. Then the current video
* state is set to the data values stored in the upper console layer for the
* virtual terminal you are switching to. As you can see doing this makes
* the con parameter pretty much useless for the fb_ops functions, as it
* should be. Also having fb_var_screeninfo and other data in fb_info pretty
* much eliminates the need for get_fix and get_var. Once all drivers use the
* fix, var, and cmap field fbcon can be written around these fields. This
* will also eliminate the need to regenerate fb_var_screeninfo and
* fb_fix_screeninfo data every time the get_var and get_fix functions are
* called as many drivers do now. The fb_var_screeninfo and
* fb_fix_screeninfo field in fb_info can be generated just in set_var and
* placed into struct fb_info.
*
* 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>
/*
* This is just simple sample code.
*
* No warranty that it actually compiles.
* Even less warranty that it actually works :-)
*/
/*
* This structure defines the hardware state of the graphics card. Normally
* you place this in a header file in linux/include/video. This file usually
* also includes register information. That allows other driver subsystems
* and userland applications the ability to use the same header file to
* avoid duplicate work and easy porting of software.
*/
struct xxx_par;
/*
* Here we define the default structs fb_fix_screeninfo and fb_var_screeninfo
* if we don't use modedb. If we do use modedb see xxxfb_init how to use it
* to get a fb_var_screeninfo. Otherwise define a default var as well.
*/
static struct fb_fix_screeninfo xxxfb_fix __initdata = {
"FB's name", (unsigned long) NULL, 0, FB_TYPE_PACKED_PIXELS, 0,
FB_VISUAL_PSEUDOCOLOR, 1, 1, 1, 0, (unsigned long) NULL, 0, FB_ACCEL_NONE
};
/*
* Modern graphical hardware not only supports pipelines but some
* also support multiple monitors where each display can have its
* its own unique data. In this case each display could be
* represented by a seperate framebuffer device thus a seperate
* struct fb_info. In this case all of the par structures for the
* graphics card would be shared between each struct fb_info. This
* allows when one display changes it video resolution (info->var)
* the other displays know instantly. Each display can always be
* aware of the entire hardware state that affects it. The other side
* of the coin is multiple graphics cards that pass data around until
* it is finally displayed on one monitor. Such examples are the
* voodoo 1 cards and high end NUMA graphics servers. I hope this
* covers every possible hardware design. If not feel free to send
* me more design types.
*/
/*
* If your driver supports multiple boards, you should make these
* arrays, or allocate them dynamically (using kmalloc()).
*/
static struct fb_info info;
/*
* This represents the default state of the hardware.
*/
static struct xxx_par __initdata current_par;
static u32 xxxfb_pseudo_palette[17];
static int inverse = 0;
int xxxfb_init(void);
int xxxfb_setup(char*);
/**
* xxxfb_check_var - REQUIRED function. Validates a var passed in.
* @var: frame buffer variable screen structure
* @info: frame buffer structure that represents a single frame buffer
*
* Checks to see if the hardware supports the state requested by
* var passed in. This function does not alter the hardware state!!!
* This means the data stored in fb_info, par and var, do not change.
* Do NOT change these. This function can be called on its own if we
* intent to only test a mode and not actually set it. The stuff in
* modedb.c is a example of this. If the var passed in is slightly
* off by what the hardware can support then we alter the var PASSED in
* to what we can do. If the hardware doesn't support mode change
* just return a -EINVAL;
*
* Returns negative errno on error, or zero on success.
*/
static int xxxfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
{
const struct xxx_par *par = (const struct xxx_par *) info->par;
/* ... */
return 0;
}
/**
* xxxfb_set_par - NOT a required function. Alters the hardware state.
* @info: frame buffer structure that represents a single frame buffer
*
* Using the fb_var_screeninfo in fb_info we set the resolution of the
* this particular framebuffer. This function alters the par AND the
* fb_fix_screeninfo stored in fb_info. It doesn't not alter var in
* fb_info since we are using that data. This means we depend on the
* data in var inside fb_info to be supported by the hardware.
* xxxfb_check_var is always called before xxxfb_set_par to ensure this.
*
*/
static void xxxfb_set_par(struct fb_info *info)
{
struct xxx_par *par = (struct xxx_par *) info->par;
/* ... */
}
/**
* xxxfb_setcolreg - REQUIRED function. Sets a color register.
* @regno: boolean, 0 copy local, 1 get_user() function
* @red: frame buffer colormap structure
* @green: The green value which can be up to 16 bits wide
* @blue: The blue value which can be up to 16 bits wide.
* @transp: If supported the alpha value which can be up to 16 bits wide.
* @info: frame buffer info structure
*
* Set a single color register. The values supplied have a 16 bit
* magnitude which needs to be scaled in this function for the hardware.
* Things to take into consideration are how many color registers, if
* any, are supported with the current color visual. With truecolor mode
* no color palettes are supported. Here a psuedo palette is created
* which we store the value in pseudo_palette in struct fb_info. For
* pseudocolor mode we have a limited color palette. To deal with this
* we can program what color is displayed for a particular pixel value.
* DirectColor is similar in that we can program each color field.
*
* Returns negative errno on error, or zero on success.
*/
static int xxxfb_setcolreg(unsigned regno, unsigned red, unsigned green,
unsigned blue, unsigned transp,
const struct fb_info *info)
{
if (regno >= 256) /* no. of hw registers */
return 1;
/*
* Program hardware... do anything you want with transp
*/
/* grayscale works only partially under directcolor */
if (info->var.grayscale) {
/* grayscale = 0.30*R + 0.59*G + 0.11*B */
red = green = blue = (red * 77 + green * 151 + blue * 28) >> 8;
}
/* Directcolor:
* var->{color}.offset contains start of bitfield
* var->{color}.length contains length of bitfield
* {hardwarespecific} contains width of DAC
* cmap[X] is programmed to (X << red.offset) | (X << green.offset) | (X << blue.offset)
* DAC[X] is programmed to (red, green, blue)
*
* Pseudocolor:
* uses offset = 0 && length = DAC register width.
* var->{color}.offset is 0
* var->{color}.length contains widht of DAC
* cmap is not used
* DAC[X] is programmed to (red, green, blue)
* Truecolor:
* does not use DAC.
* var->{color}.offset contains start of bitfield
* var->{color}.length contains length of bitfield
* cmap is programmed to (red << red.offset) | (green << green.offset) |
* (blue << blue.offset) | (transp << transp.offset)
* DAC does not exist
*/
#define CNVT_TOHW(val,width) ((((val)<<(width))+0x7FFF-(val))>>16)
switch (info->fix.visual) {
case FB_VISUAL_TRUECOLOR:
case FB_VISUAL_PSEUDOCOLOR:
red = CNVT_TOHW(red, info->var.red.length);
green = CNVT_TOHW(green, info->var.green.length);
blue = CNVT_TOHW(blue, info->var.blue.length);
transp = CNVT_TOHW(transp, info->var.transp.length);
break;
case FB_VISUAL_DIRECTCOLOR:
/* example here assumes 8 bit DAC. Might be different
* for your hardware */
red = CNVT_TOHW(red, 8);
green = CNVT_TOHW(green, 8);
blue = CNVT_TOHW(blue, 8);
/* hey, there is bug in transp handling... */
transp = CNVT_TOHW(transp, 8);
break;
}
#undef CNVT_TOHW
/* Truecolor has hardware independent palette */
if (info->fix.visual == FB_VISUAL_TRUECOLOR) {
u32 v;
if (regno >= 16)
return 1;
v = (red << info->var.red.offset) |
(green << info->var.green.offset) |
(blue << info->var.blue.offset) |
(transp << info->var.transp.offset);
if (info->var.bits_per_pixel == 16)
((u16*)(info->pseudo_palette))[regno] = v;
else
((u32*)(info->pseudo_palette))[regno] = v;
return 0;
}
/* ... */
return 0;
}
/**
* xxxfb_pan_display - NOT a required function. Pans the display.
* @var: frame buffer variable screen structure
* @info: frame buffer structure that represents a single frame buffer
*
* 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.
*
* Returns negative errno on error, or zero on success.
*
*/
static int xxxfb_pan_display(struct fb_var_screeninfo *var,
const struct fb_info *info)
{
/* ... */
return 0;
}
/**
* xxxfb_blank - NOT a required function. Blanks the display.
* @blank_mode: the blank mode we want.
* @info: frame buffer structure that represents a single frame buffer
*
* Blank the screen if blank_mode != 0, else unblank. 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
*
* Returns negative errno on error, or zero on success.
*
*/
static int xxxfb_blank(int blank_mode, const struct fb_info *info)
{
/* ... */
return 0;
}
/* ------------ Accelerated Functions --------------------- */
/*
* We provide our own functions if we have hardware acceleration
* or non packed pixel format layouts.
*/
/**
* xxxfb_fillrect - REQUIRED function. Can use generic routines if
* non acclerated hardware and packed pixel based.
* Draws a rectangle on the screen.
*
* @info: frame buffer structure that represents a single frame buffer
* @x1: The x and y corrdinates of the upper left hand corner of the
* @y1: area we want to draw to.
* @width: How wide the rectangle is we want to draw.
* @height: How tall the rectangle is we want to draw.
* @color: The color to fill in the rectangle with.
* @rop: The rater operation. We can draw the rectangle with a COPY
* of XOR which provides erasing effect.
*
* This drawing operation places/removes a retangle on the screen
* depending on the rastering operation with the value of color which
* is in the current color depth format.
*/
void xxxfb_fillrect(struct fb_info *p, int x1, int y1, unsigned int width,
unsigned int height, unsigned long color, int rop)
{
}
/**
* xxxfb_copyarea - REQUIRED function. Can use generic routines if
* non acclerated hardware and packed pixel based.
* Copies on area of the screen to another area.
*
* @info: frame buffer structure that represents a single frame buffer
* @sx: The x and y corrdinates of the upper left hand corner of the
* @sy: source area on the screen.
* @width: How wide the rectangle is we want to copy.
* @height: How tall the rectangle is we want to copy.
* @dx: The x and y coordinates of the destination area on the screen.
*
* This drawing operation copies a rectangular area from one area of the
* screen to another area.
*/
void xxxfb_copyarea(struct fb_info *p, int sx, int sy, unsigned int width,
unsigned int height, int dx, int dy)
{
}
/**
* xxxfb_imageblit - REQUIRED function. Can use generic routines if
* non acclerated hardware and packed pixel based.
* Copies a image from system memory to the screen.
*
* @info: frame buffer structure that represents a single frame buffer
* @image: structure defining the image.
*
* This drawing operation draws a image on the screen. It can be a
* mono image (needed for font handling) or a color image (needed for
* tux).
*/
void xxxfb_imageblit(struct fb_info *p, struct fb_image *image)
{
}
/* ------------ Hardware Independent Functions ------------ */
/*
* Initialization
*/
int __init xxxfb_init(void)
{
int retval;
/*
* Here we set the screen_base to the vitrual memory address
* for the framebuffer. Usually we obtain the resource address
* from the bus layer and then translate it to virtual memory
* space via ioremap. Consult ioport.h.
*/
info.screen_base = framebuffer_virtual_memory;
info.node = -1;
info.fbops = &xxxfb_ops;
info.fix = xxxfb_fix;
info.par = current_par;
info.pseudo_palette = xxxfb_pseudo_palette;
info.flags = FBINFO_FLAG_DEFAULT;
/* This should give a reasonable default video mode */
if (!mode_option)
mode_option = "640x480@60";
retval = fb_find_mode(&info.var, &info, mode_option, NULL, 0, NULL, 8);
if (!retval || retval == 4)
return -EINVAL;
info.cmap = fb_default_cmap(1<<info.var.bits_per_pixel);
if (register_framebuffer(&info) < 0)
return -EINVAL;
printk(KERN_INFO "fb%d: %s frame buffer device\n", GET_FB_IDX(info.node),
info.fix.id);
/* uncomment this if your driver cannot be unloaded */
/* MOD_INC_USE_COUNT; */
return 0;
}
/*
* Cleanup
*/
static void __exit xxxfb_cleanup(void)
{
/*
* If your driver supports multiple boards, you should unregister and
* clean up all instances.
*/
unregister_framebuffer(info);
/* ... */
}
/*
* Setup
*/
/*
* Only necessary if your driver takes special options,
* otherwise we fall back on the generic fb_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;
}
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_check_var: xxxfb_check_var,
fb_set_par: xxxfb_set_par, /* optional */
fb_setcolreg: xxxfb_setcolreg,
fb_blank: xxxfb_blank, /* optional */
fb_pan_display: xxxfb_pan_display, /* optional */
fb_fillrect: xxxfb_fillrect,
fb_copyarea: xxxfb_copyarea,
fb_imageblit: xxxfb_imageblit,
fb_ioctl: xxxfb_ioctl, /* optional */
fb_mmap: xxxfb_mmap, /* optional */
};
/* ------------------------------------------------------------------------- */
/*
* Modularization
*/
#ifdef MODULE
module_init(xxxfb_init);
module_exit(xxxfb_cleanup);
MODULE_LICENSE("GPL");
#endif /* MODULE */
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