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|
/*
* linux/drivers/video/skeletonfb.c -- Skeleton for a frame buffer device
*
* Modified to new api Jan 2001 by James Simmons (jsimmons@transvirtual.com)
*
* 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/tty system on top
* of it.
*
* First the roles of struct fb_info and struct display have changed. Struct
* display will go away. The way the new framebuffer console code will
* work is that it will act to translate data about the tty/console in
* struct vc_data to data in a device independent way in struct fb_info. Then
* various functions in struct fb_ops will be called to store the device
* dependent state in the par field in struct fb_info and to change the
* hardware to that state. This allows a very clean separation of the fbdev
* layer from the console layer. It also allows one to use fbdev on its own
* which is a bounus for embedded devices. The reason this approach works is
* for each framebuffer device when used as a tty/console device is allocated
* a set of virtual terminals to it. Only one virtual terminal can be active
* per framebuffer device. We already have all the data we need in struct
* vc_data so why store a bunch of colormaps and other fbdev specific data
* per virtual terminal.
*
* As you can see doing this makes the con parameter pretty much useless
* for struct fb_ops functions, as it should be. Also having struct
* 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
* fbcon can be written around these fields. This will also eliminate the
* need to regenerate struct fb_var_screeninfo, struct fb_fix_screeninfo
* struct fb_cmap every time get_var, get_fix, get_cmap functions are called
* as many drivers do now.
*
* 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/slab.h>
#include <linux/delay.h>
#include <linux/fb.h>
#include <linux/init.h>
#include <linux/pci.h>
/*
* This is just simple sample code.
*
* No warranty that it actually compiles.
* Even less warranty that it actually works :-)
*/
/*
* Driver data
*/
static char *mode_option;
/*
* If your driver supports multiple boards, you should make the
* below data types arrays, or allocate them dynamically (using kmalloc()).
*/
/*
* 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 = {
.id = "FB's name",
.type = FB_TYPE_PACKED_PIXELS,
.visual = FB_VISUAL_PSEUDOCOLOR,
.xpanstep = 1,
.ypanstep = 1,
.ywrapstep = 1,
.accel = 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 separate framebuffer device thus a separate
* struct fb_info. Now the struct xxx_par represents the graphics
* hardware state thus only one exist per card. In this case the
* struct xxx_par for each graphics card would be shared between
* every struct fb_info that represents a framebuffer on that card.
* 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 because they share
* the same xxx_par struct. 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. For this case we have a bunch of pars, each
* one that represents a graphics state, that belong to one struct
* fb_info. Their you would want to have *par point to a array of device
* states and have each struct fb_ops function deal with all those
* states. I hope this covers every possible hardware design. If not
* feel free to send your ideas at jsimmons@users.sf.net
*/
/*
* If your driver supports multiple boards or it supports multiple
* framebuffers, you should make these arrays, or allocate them
* dynamically using framebuffer_alloc() and free them with
* framebuffer_release().
*/
static struct fb_info info;
/*
* Each one represents the state of the hardware. Most hardware have
* just one hardware state. These here represent the default state(s).
*/
static struct xxx_par __initdata current_par;
int xxxfb_init(void);
/**
* xxxfb_open - Optional function. Called when the framebuffer is
* first accessed.
* @info: frame buffer structure that represents a single frame buffer
* @user: tell us if the userland (value=1) or the console is accessing
* the framebuffer.
*
* This function is the first function called in the framebuffer api.
* Usually you don't need to provide this function. The case where it
* is used is to change from a text mode hardware state to a graphics
* mode state.
*
* Returns negative errno on error, or zero on success.
*/
static int xxxfb_open(struct fb_info *info, int user)
{
return 0;
}
/**
* xxxfb_release - Optional function. Called when the framebuffer
* device is closed.
* @info: frame buffer structure that represents a single frame buffer
* @user: tell us if the userland (value=1) or the console is accessing
* the framebuffer.
*
* Thus function is called when we close /dev/fb or the framebuffer
* console system is released. Usually you don't need this function.
* The case where it is usually used is to go from a graphics state
* to a text mode state.
*
* Returns negative errno on error, or zero on success.
*/
static int xxxfb_release(struct fb_info *info, int user)
{
return 0;
}
/**
* xxxfb_check_var - Optional 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 struct fb_info and struct xxx_par do
* not change. This includes the var inside of struct fb_info.
* 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.
*
* For values that are off, this function must round them _up_ to the
* next value that is supported by the hardware. If the value is
* greater than the highest value supported by the hardware, then this
* function must return -EINVAL.
*
* Exception to the above rule: Some drivers have a fixed mode, ie,
* the hardware is already set at boot up, and cannot be changed. In
* this case, it is more acceptable that this function just return
* a copy of the currently working var (info->var). Better is to not
* implement this function, as the upper layer will do the copying
* of the current var for you.
*
* Note: This is the only function where the contents of var can be
* freely adjusted after the driver has been registered. If you find
* that you have code outside of this function that alters the content
* of var, then you are doing something wrong. Note also that the
* contents of info->var must be left untouched at all times after
* driver registration.
*
* Returns negative errno on error, or zero on success.
*/
static int xxxfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
{
/* ... */
return 0;
}
/**
* xxxfb_set_par - Optional 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.
*
* This function is also used to recover/restore the hardware to a
* known working state.
*
* xxxfb_check_var is always called before xxxfb_set_par to ensure that
* the contents of var is always valid.
*
* Again if you can't change the resolution you don't need this function.
*
* However, even if your hardware does not support mode changing,
* a set_par might be needed to at least initialize the hardware to
* a known working state, especially if it came back from another
* process that also modifies the same hardware, such as X.
*
* If this is the case, a combination such as the following should work:
*
* static int xxxfb_check_var(struct fb_var_screeninfo *var,
* struct fb_info *info)
* {
* *var = info->var;
* return 0;
* }
*
* static int xxxfb_set_par(struct fb_info *info)
* {
* init your hardware here
* }
*
* Returns negative errno on error, or zero on success.
*/
static int xxxfb_set_par(struct fb_info *info)
{
struct xxx_par *par = info->par;
/* ... */
|