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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 const 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 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;
 
 /**
  *  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;
     /* ... */
     return 0;   
 }
 
 /**
  *      xxxfb_setcolreg - Optional function. Sets a color register.
  *      @regno: Which register in the CLUT we are programming 
  *      @red: The red value which can be up to 16 bits wide 
  *  @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 pseudo 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. If
  *  we have a static colormap we don't need to implement this function. 
  * 
  *  Returns negative errno on error, or zero on success.
  */
 static int xxxfb_setcolreg(unsigned regno, unsigned red, unsigned green,
                unsigned blue, unsigned transp,
                struct fb_info *info)
 {
     if (regno >= 256)  /* no. of hw registers */
        return -EINVAL;
     /*
      * 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
      *   pseudo_palette[X] is programmed to (X << red.offset) |
      *                                      (X << green.offset) |
      *                                      (X << blue.offset)
      *   RAMDAC[X] is programmed to (red, green, blue)
      *   color depth = SUM(var->{color}.length)
      *
      * Pseudocolor:
      *    var->{color}.offset is 0 unless the palette index takes less than
      *                        bits_per_pixel bits and is stored in the upper
      *                        bits of the pixel value
      *    var->{color}.length is set so that 1 << length is the number of
      *                        available palette entries
      *    pseudo_palette is not used
      *    RAMDAC[X] is programmed to (red, green, blue)
      *    color depth = var->{color}.length
      *
      * Static pseudocolor:
      *    same as Pseudocolor, but the RAMDAC is not programmed (read-only)
      *
      * Mono01/Mono10:
      *    Has only 2 values, black on white or white on black (fg on bg),
      *    var->{color}.offset is 0
      *    white = (1 << var->{color}.length) - 1, black = 0
      *    pseudo_palette is not used
      *    RAMDAC does not exist
      *    color depth is always 2
      *
      * Truecolor:
      *    does not use RAMDAC (usually has 3 of them).
      *    var->{color}.offset contains start of bitfield
      *    var->{color}.length contains length of bitfield
      *    pseudo_palette is programmed to (red << red.offset) |
      *                                    (green << green.offset) |
      *                                    (blue << blue.offset) |
      *                                    (transp << transp.offset)
      *    RAMDAC does not exist
      *    color depth = SUM(var->{color}.length})
      *
      *  The color depth is used by fbcon for choosing the logo and also
      *  for color palette transformation if color depth < 4
      *
      *  As can be seen from the above, the field bits_per_pixel is _NOT_
      *  a criteria for describing the color visual.
      *
      *  A common mistake is assuming that bits_per_pixel <= 8 is pseudocolor,
      *  and higher than that, true/directcolor.  This is incorrect, one needs
      *  to look at the fix->visual.
      *
      *  Another common mistake is using bits_per_pixel to calculate the color
      *  depth.  The bits_per_pixel field does not directly translate to color
      *  depth. You have to compute for the color depth (using the color
      *  bitfields) and fix->visual as seen above.
      */
 
     /*
      * This is the point where the color is converted to something that
      * is acceptable by the hardware.
      */
 #define CNVT_TOHW(val,width) ((((val)<<(width))+0x7FFF-(val))>>16)
     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);
 #undef CNVT_TOHW
     /*
      * This is the point where the function feeds the color to the hardware
      * palette after converting the colors to something acceptable by
      * the hardware. Note, only FB_VISUAL_DIRECTCOLOR and
      * FB_VISUAL_PSEUDOCOLOR visuals need to write to the hardware palette.
      * If you have code that writes to the hardware CLUT, and it's not
      * any of the above visuals, then you are doing something wrong.
      */
     if (info->fix.visual == FB_VISUAL_DIRECTCOLOR ||
     info->fix.visual == FB_VISUAL_TRUECOLOR)
         write_{red|green|blue|transp}_to_clut();
 
     /* This is the point were you need to fill up the contents of
      * info->pseudo_palette. This structure is used _only_ by fbcon, thus
      * it only contains 16 entries to match the number of colors supported
      * by the console. The pseudo_palette is used only if the visual is
      * in directcolor or truecolor mode.  With other visuals, the
      * pseudo_palette is not used. (This might change in the future.)
      *
      * The contents of the pseudo_palette is in raw pixel format.  Ie, each
      * entry can be written directly to the framebuffer without any conversion.
      * The pseudo_palette is (void *).  However, if using the generic
      * drawing functions (cfb_imageblit, cfb_fillrect), the pseudo_palette
      * must be casted to (u32 *) _regardless_ of the bits per pixel. If the
      * driver is using its own drawing functions, then it can use whatever
      * size it wants.
      */
     if (info->fix.visual == FB_VISUAL_TRUECOLOR ||
     info->fix.visual == FB_VISUAL_DIRECTCOLOR) {
         u32 v;
 
         if (regno >= 16)
             return -EINVAL;
 
         v = (red << info->var.red.offset) |
             (green << info->var.green.offset) |
             (blue << info->var.blue.offset) |
             (transp << info->var.transp.offset);
 
         ((u32*)(info->pseudo_palette))[regno] = v;
     }
 
     /* ... */
     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,
                  struct fb_info *info)
 {
     /*
      * If your hardware does not support panning, _do_ _not_ implement this
      * function. Creating a dummy function will just confuse user apps.
      */
 
     /*
      * Note that even if this function is fully functional, a setting of
      * 0 in both xpanstep and ypanstep means that this function will never
      * get called.
      */
 
     /* ... */
     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 != FB_BLANK_UNBLANK, 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:
  *
  *      FB_BLANK_NORMAL = display is blanked, syncs are on.
  *      FB_BLANK_HSYNC_SUSPEND = hsync off
  *      FB_BLANK_VSYNC_SUSPEND = vsync off
  *      FB_BLANK_POWERDOWN =  hsync and vsync off
  *
  *      If implementing this function, at least support FB_BLANK_UNBLANK.
  *      Return !0 for any modes that are unimplemented.
  *
  */
 static int xxxfb_blank(int blank_mode, struct fb_info *info)
 {
     /* ... */
     return 0;
 }
 
 /* ------------ Accelerated Functions --------------------- */
 
 /*
  * We provide our own functions if we have hardware acceleration
  * or non packed pixel format layouts. If we have no hardware 
  * acceleration, we can use a generic unaccelerated function. If using
  * a pack pixel format just use the functions in cfb_*.c. Each file 
  * has one of the three different accel functions we support.
  */
 
 /**
  *      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
  *  @region: The structure representing the rectangular region we 
  *       wish to draw to.
  *
  *  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, const struct fb_fillrect *region)
 {
 /*  Meaning of struct fb_fillrect
  *
  *  @dx: The x and y corrdinates of the upper left hand corner of the 
  *  @dy: 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 raster operation. We can draw the rectangle with a COPY
  *        of XOR which provides erasing effect. 
  */
 }
 
 /**
  *      xxxfb_copyarea - REQUIRED function. Can use generic routines if
  *                       non acclerated hardware and packed pixel based.
  *                       Copies one area of the screen to another area.
  *
  *      @info: frame buffer structure that represents a single frame buffer
  *      @area: Structure providing the data to copy the framebuffer contents
  *         from one region to another.
  *
  *      This drawing operation copies a rectangular area from one area of the
  *  screen to another area.
  */
 void xxxfb_copyarea(struct fb_info *p, const struct fb_copyarea *area) 
 {
 /*
  *      @dx: The x and y coordinates of the upper left hand corner of the
  *  @dy: destination area on the screen.
  *      @width: How wide the rectangle is we want to copy.
  *      @height: How tall the rectangle is we want to copy.
  *      @sx: The x and y coordinates of the upper left hand corner of the
  *      @sy: source area on the screen.
  */
 }
 
 
 /**
  *      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, const struct fb_image *image) 
 {
 /*
  *      @dx: The x and y coordinates of the upper left hand corner of the
  *  @dy: destination area to place the image on the screen.
  *      @width: How wide the image is we want to copy.
  *      @height: How tall the image is we want to copy.
  *      @fg_color: For mono bitmap images this is color data for     
  *      @bg_color: the foreground and background of the image to
  *         write directly to the frmaebuffer.
  *  @depth: How many bits represent a single pixel for this image.
  *  @data: The actual data used to construct the image on the display.
  *  @cmap: The colormap used for color images.   
  */
 
 /*
  * The generic function, cfb_imageblit, expects that the bitmap scanlines are
  * padded to the next byte.  Most hardware accelerators may require padding to
  * the next u16 or the next u32.  If that is the case, the driver can specify
  * this by setting info->pixmap.scan_align = 2 or 4.  See a more
  * comprehensive description of the pixmap below.
  */
 }
 
 /**
  *  xxxfb_cursor -  OPTIONAL. If your hardware lacks support
  *          for a cursor, leave this field NULL.
  *
  *      @info: frame buffer structure that represents a single frame buffer
  *  @cursor: structure defining the cursor to draw.
  *
  *      This operation is used to set or alter the properities of the
  *  cursor.
  *
  *  Returns negative errno on error, or zero on success.
  */
 int xxxfb_cursor(struct fb_info *info, struct fb_cursor *cursor)
 {
 /*
  *      @set:   Which fields we are altering in struct fb_cursor 
  *  @enable: Disable or enable the cursor 
  *      @rop:   The bit operation we want to do. 
  *      @mask:  This is the cursor mask bitmap. 
  *      @dest:  A image of the area we are going to display the cursor.
  *      Used internally by the driver.   
  *      @hot:   The hot spot. 
  *  @image: The actual data for the cursor image.
  *
  *      NOTES ON FLAGS (cursor->set):
  *
  *      FB_CUR_SETIMAGE - the cursor image has changed (cursor->image.data)
  *      FB_CUR_SETPOS   - the cursor position has changed (cursor->image.dx|dy)
  *      FB_CUR_SETHOT   - the cursor hot spot has changed (cursor->hot.dx|dy)
  *      FB_CUR_SETCMAP  - the cursor colors has changed (cursor->fg_color|bg_color)
  *      FB_CUR_SETSHAPE - the cursor bitmask has changed (cursor->mask)
  *      FB_CUR_SETSIZE  - the cursor size has changed (cursor->width|height)
  *      FB_CUR_SETALL   - everything has changed
  *
  *      NOTES ON ROPs (cursor->rop, Raster Operation)
  *
  *      ROP_XOR         - cursor->image.data XOR cursor->mask
  *      ROP_COPY        - curosr->image.data AND cursor->mask
  *
  *      OTHER NOTES:
  *
  *      - fbcon only supports a 2-color cursor (cursor->image.depth = 1)
  *      - The fb_cursor structure, @cursor, _will_ always contain valid
  *        fields, whether any particular bitfields in cursor->set is set
  *        or not.
  */
 }
 
 /**
  *  xxxfb_sync - NOT a required function. Normally the accel engine 
  *           for a graphics card take a specific amount of time.
  *           Often we have to wait for the accelerator to finish
  *           its operation before we can write to the framebuffer
  *           so we can have consistent display output. 
  *
  *      @info: frame buffer structure that represents a single frame buffer
  *
  *      If the driver has implemented its own hardware-based drawing function,
  *      implementing this function is highly recommended.
  */
 int xxxfb_sync(struct fb_info *info)
 {
     return 0;
 }
 
     /*
      *  Frame buffer operations
      */
 
 static const struct fb_ops xxxfb_ops = {
     .owner      = THIS_MODULE,
     .fb_open    = xxxfb_open,
     .fb_read    = xxxfb_read,
     .fb_write   = xxxfb_write,
     .fb_release = xxxfb_release,
     .fb_check_var   = xxxfb_check_var,
     .fb_set_par = xxxfb_set_par,
     .fb_setcolreg   = xxxfb_setcolreg,
     .fb_blank   = xxxfb_blank,
     .fb_pan_display = xxxfb_pan_display,
     .fb_fillrect    = xxxfb_fillrect,   /* Needed !!! */
     .fb_copyarea    = xxxfb_copyarea,   /* Needed !!! */
     .fb_imageblit   = xxxfb_imageblit,  /* Needed !!! */
     .fb_cursor  = xxxfb_cursor,     /* Optional !!! */
     .fb_sync    = xxxfb_sync,
     .fb_ioctl   = xxxfb_ioctl,
     .fb_mmap    = xxxfb_mmap,
 };
 
 /* ------------------------------------------------------------------------- */
 
     /*
      *  Initialization
      */
 
 /* static int __init xxfb_probe (struct platform_device *pdev) -- for platform devs */
 static int xxxfb_probe(struct pci_dev *dev, const struct pci_device_id *ent)
 {
     struct fb_info *info;
     struct xxx_par *par;
     struct device *device = &dev->dev; /* or &pdev->dev */
     int cmap_len, retval;   
    
     /*
      * Dynamically allocate info and par
      */
     info = framebuffer_alloc(sizeof(struct xxx_par), device);
 
     if (!info) {
         /* goto error path */
     }
 
     par = info->par;
 
     /* 
      * Here we set the screen_base to the virtual 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->fbops = &xxxfb_ops;
     info->fix = xxxfb_fix;
     info->pseudo_palette = pseudo_palette; /* The pseudopalette is an
                         * 16-member array
                         */
     /*
      * Set up flags to indicate what sort of acceleration your
      * driver can provide (pan/wrap/copyarea/etc.) and whether it
      * is a module -- see FBINFO_* in include/linux/fb.h
      *
      * If your hardware can support any of the hardware accelerated functions
      * fbcon performance will improve if info->flags is set properly.
      *
      * FBINFO_HWACCEL_COPYAREA - hardware moves
      * FBINFO_HWACCEL_FILLRECT - hardware fills
      * FBINFO_HWACCEL_IMAGEBLIT - hardware mono->color expansion
      * FBINFO_HWACCEL_YPAN - hardware can pan display in y-axis
      * FBINFO_HWACCEL_YWRAP - hardware can wrap display in y-axis
      * FBINFO_HWACCEL_DISABLED - supports hardware accels, but disabled
      * FBINFO_READS_FAST - if set, prefer moves over mono->color expansion
      * FBINFO_MISC_TILEBLITTING - hardware can do tile blits
      *
      * NOTE: These are for fbcon use only.
      */
     info->flags = FBINFO_DEFAULT;
 
 /********************* This stage is optional ******************************/
      /*
      * The struct pixmap is a scratch pad for the drawing functions. This
      * is where the monochrome bitmap is constructed by the higher layers
      * and then passed to the accelerator.  For drivers that uses
      * cfb_imageblit, you can skip this part.  For those that have a more
      * rigorous requirement, this stage is needed
      */
 
     /* PIXMAP_SIZE should be small enough to optimize drawing, but not
      * large enough that memory is wasted.  A safe size is
      * (max_xres * max_font_height/8). max_xres is driver dependent,
      * max_font_height is 32.
      */
     info->pixmap.addr = kmalloc(PIXMAP_SIZE, GFP_KERNEL);
     if (!info->pixmap.addr) {
         /* goto error */
     }
 
     info->pixmap.size = PIXMAP_SIZE;
 
     /*
      * FB_PIXMAP_SYSTEM - memory is in system ram
      * FB_PIXMAP_IO     - memory is iomapped
      * FB_PIXMAP_SYNC   - if set, will call fb_sync() per access to pixmap,
      *                    usually if FB_PIXMAP_IO is set.
      *
      * Currently, FB_PIXMAP_IO is unimplemented.
      */
     info->pixmap.flags = FB_PIXMAP_SYSTEM;
 
     /*
      * scan_align is the number of padding for each scanline.  It is in bytes.
      * Thus for accelerators that need padding to the next u32, put 4 here.
      */
     info->pixmap.scan_align = 4;
 
     /*
      * buf_align is the amount to be padded for the buffer. For example,
      * the i810fb needs a scan_align of 2 but expects it to be fed with
      * dwords, so a buf_align = 4 is required.
      */
     info->pixmap.buf_align = 4;
 
     /* access_align is how many bits can be accessed from the framebuffer
      * ie. some epson cards allow 16-bit access only.  Most drivers will
      * be safe with u32 here.
      *
      * NOTE: This field is currently unused.
      */
     info->pixmap.access_align = 32;
 /***************************** End optional stage ***************************/
 
     /*
      * This should give a reasonable default video mode. The following is
      * done when we can set a 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;         
 
     /* This has to be done! */
     if (fb_alloc_cmap(&info->cmap, cmap_len, 0))
     return -ENOMEM;
     
     /* 
      * The following is done in the case of having hardware with a static 
      * mode. If we are setting the mode ourselves we don't call this. 
      */ 
     info->var = xxxfb_var;
 
     /*
      * For drivers that can...
      */
     xxxfb_check_var(&info->var, info);
 
     /*
      * Does a call to fb_set_par() before register_framebuffer needed?  This
      * will depend on you and the hardware.  If you are sure that your driver
      * is the only device in the system, a call to fb_set_par() is safe.
      *
      * Hardware in x86 systems has a VGA core.  Calling set_par() at this
      * point will corrupt the VGA console, so it might be safer to skip a
      * call to set_par here and just allow fbcon to do it for you.
      */
     /* xxxfb_set_par(info); */
 
     if (register_framebuffer(info) < 0) {
     fb_dealloc_cmap(&info->cmap);
     return -EINVAL;
     }
     fb_info(info, "%s frame buffer device\n", info->fix.id);
     pci_set_drvdata(dev, info); /* or platform_set_drvdata(pdev, info) */
     return 0;
 }
 
     /*
      *  Cleanup
      */
 /* static void xxxfb_remove(struct platform_device *pdev) */
 static void xxxfb_remove(struct pci_dev *dev)
 {
     struct fb_info *info = pci_get_drvdata(dev);
     /* or platform_get_drvdata(pdev); */
 
     if (info) {
         unregister_framebuffer(info);
         fb_dealloc_cmap(&info->cmap);
         /* ... */
         framebuffer_release(info);
     }
 }
 
 #ifdef CONFIG_PCI
 #ifdef CONFIG_PM
 /**
  *  xxxfb_suspend - Optional but recommended function. Suspend the device.
  *  @dev: PCI device
  *  @msg: the suspend event code.
  *
  *      See Documentation/driver-api/pm/devices.rst for more information
  */
 static int xxxfb_suspend(struct device *dev)
 {
     struct fb_info *info = dev_get_drvdata(dev);
     struct xxxfb_par *par = info->par;
 
     /* suspend here */
     return 0;
 }
 
 /**
  *  xxxfb_resume - Optional but recommended function. Resume the device.
  *  @dev: PCI device
  *
  *      See Documentation/driver-api/pm/devices.rst for more information
  */
 static int xxxfb_resume(struct device *dev)
 {
     struct fb_info *info = dev_get_drvdata(dev);
     struct xxxfb_par *par = info->par;
 
     /* resume here */
     return 0;
 }
 #else
 #define xxxfb_suspend NULL
 #define xxxfb_resume NULL
 #endif /* CONFIG_PM */
 
 static const struct pci_device_id xxxfb_id_table[] = {
     { PCI_VENDOR_ID_XXX, PCI_DEVICE_ID_XXX,
       PCI_ANY_ID, PCI_ANY_ID, PCI_BASE_CLASS_DISPLAY << 16,
       PCI_CLASS_MASK, 0 },
     { 0, }
 };
 
 static SIMPLE_DEV_PM_OPS(xxxfb_pm_ops, xxxfb_suspend, xxxfb_resume);
 
 /* For PCI drivers */
 static struct pci_driver xxxfb_driver = {
     .name =     "xxxfb",
     .id_table = xxxfb_id_table,
     .probe =    xxxfb_probe,
     .remove =   xxxfb_remove,
     .driver.pm =    xxxfb_pm_ops, /* optional but recommended */
 };
 
 MODULE_DEVICE_TABLE(pci, xxxfb_id_table);
 
 static int __init xxxfb_init(void)
 {
     /*
      *  For kernel boot options (in 'video=xxxfb:<options>' format)
      */
 #ifndef MODULE
     char *option = NULL;
 
     if (fb_get_options("xxxfb", &option))
         return -ENODEV;
     xxxfb_setup(option);
 #endif
 
     return pci_register_driver(&xxxfb_driver);
 }
 
 static void __exit xxxfb_exit(void)
 {
     pci_unregister_driver(&xxxfb_driver);
 }
 #else /* non PCI, platform drivers */
 #include <linux/platform_device.h>
 /* for platform devices */
 
 #ifdef CONFIG_PM
 /**
  *  xxxfb_suspend - Optional but recommended function. Suspend the device.
  *  @dev: platform device
  *  @msg: the suspend event code.
  *
  *      See Documentation/driver-api/pm/devices.rst for more information
  */
 static int xxxfb_suspend(struct platform_device *dev, pm_message_t msg)
 {
     struct fb_info *info = platform_get_drvdata(dev);
     struct xxxfb_par *par = info->par;
 
     /* suspend here */
     return 0;
 }
 
 /**
  *  xxxfb_resume - Optional but recommended function. Resume the device.
  *  @dev: platform device
  *
  *      See Documentation/driver-api/pm/devices.rst for more information
  */
 static int xxxfb_resume(struct platform_dev *dev)
 {
     struct fb_info *info = platform_get_drvdata(dev);
     struct xxxfb_par *par = info->par;
 
     /* resume here */
     return 0;
 }
 #else
 #define xxxfb_suspend NULL
 #define xxxfb_resume NULL
 #endif /* CONFIG_PM */
 
 static struct platform_device_driver xxxfb_driver = {
     .probe = xxxfb_probe,
     .remove = xxxfb_remove,
     .suspend = xxxfb_suspend, /* optional but recommended */
     .resume = xxxfb_resume,   /* optional but recommended */
     .driver = {
         .name = "xxxfb",
     },
 };
 
 static struct platform_device *xxxfb_device;
 
 #ifndef MODULE
     /*
      *  Setup
      */
 
 /*
  * Only necessary if your driver takes special options,
  * otherwise we fall back on the generic fb_setup().
  */
 static int __init xxxfb_setup(char *options)
 {
     /* Parse user specified options (`video=xxxfb:') */
 }
 #endif /* MODULE */
 
 static int __init xxxfb_init(void)
 {
     int ret;
     /*
      *  For kernel boot options (in 'video=xxxfb:<options>' format)
      */
 #ifndef MODULE
     char *option = NULL;
 
     if (fb_get_options("xxxfb", &option))
         return -ENODEV;
     xxxfb_setup(option);
 #endif
     ret = platform_driver_register(&xxxfb_driver);
 
     if (!ret) {
         xxxfb_device = platform_device_register_simple("xxxfb", 0,
                                 NULL, 0);
 
         if (IS_ERR(xxxfb_device)) {
             platform_driver_unregister(&xxxfb_driver);
             ret = PTR_ERR(xxxfb_device);
         }
     }
 
     return ret;
 }
 
 static void __exit xxxfb_exit(void)
 {
     platform_device_unregister(xxxfb_device);
     platform_driver_unregister(&xxxfb_driver);
 }
 #endif /* CONFIG_PCI */
 
 /* ------------------------------------------------------------------------- */
 
 
     /*
      *  Modularization
      */
 
 module_init(xxxfb_init);
 module_exit(xxxfb_exit);
 
 MODULE_LICENSE("GPL");

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