xref: /linux/drivers/video/fbdev/skeletonfb.c (revision f86fd32d)
1 /*
2  * linux/drivers/video/skeletonfb.c -- Skeleton for a frame buffer device
3  *
4  *  Modified to new api Jan 2001 by James Simmons (jsimmons@transvirtual.com)
5  *
6  *  Created 28 Dec 1997 by Geert Uytterhoeven
7  *
8  *
9  *  I have started rewriting this driver as a example of the upcoming new API
10  *  The primary goal is to remove the console code from fbdev and place it
11  *  into fbcon.c. This reduces the code and makes writing a new fbdev driver
12  *  easy since the author doesn't need to worry about console internals. It
13  *  also allows the ability to run fbdev without a console/tty system on top
14  *  of it.
15  *
16  *  First the roles of struct fb_info and struct display have changed. Struct
17  *  display will go away. The way the new framebuffer console code will
18  *  work is that it will act to translate data about the tty/console in
19  *  struct vc_data to data in a device independent way in struct fb_info. Then
20  *  various functions in struct fb_ops will be called to store the device
21  *  dependent state in the par field in struct fb_info and to change the
22  *  hardware to that state. This allows a very clean separation of the fbdev
23  *  layer from the console layer. It also allows one to use fbdev on its own
24  *  which is a bounus for embedded devices. The reason this approach works is
25  *  for each framebuffer device when used as a tty/console device is allocated
26  *  a set of virtual terminals to it. Only one virtual terminal can be active
27  *  per framebuffer device. We already have all the data we need in struct
28  *  vc_data so why store a bunch of colormaps and other fbdev specific data
29  *  per virtual terminal.
30  *
31  *  As you can see doing this makes the con parameter pretty much useless
32  *  for struct fb_ops functions, as it should be. Also having struct
33  *  fb_var_screeninfo and other data in fb_info pretty much eliminates the
34  *  need for get_fix and get_var. Once all drivers use the fix, var, and cmap
35  *  fbcon can be written around these fields. This will also eliminate the
36  *  need to regenerate struct fb_var_screeninfo, struct fb_fix_screeninfo
37  *  struct fb_cmap every time get_var, get_fix, get_cmap functions are called
38  *  as many drivers do now.
39  *
40  *  This file is subject to the terms and conditions of the GNU General Public
41  *  License. See the file COPYING in the main directory of this archive for
42  *  more details.
43  */
44 
45 #include <linux/module.h>
46 #include <linux/kernel.h>
47 #include <linux/errno.h>
48 #include <linux/string.h>
49 #include <linux/mm.h>
50 #include <linux/slab.h>
51 #include <linux/delay.h>
52 #include <linux/fb.h>
53 #include <linux/init.h>
54 #include <linux/pci.h>
55 
56     /*
57      *  This is just simple sample code.
58      *
59      *  No warranty that it actually compiles.
60      *  Even less warranty that it actually works :-)
61      */
62 
63 /*
64  * Driver data
65  */
66 static char *mode_option;
67 
68 /*
69  *  If your driver supports multiple boards, you should make the
70  *  below data types arrays, or allocate them dynamically (using kmalloc()).
71  */
72 
73 /*
74  * This structure defines the hardware state of the graphics card. Normally
75  * you place this in a header file in linux/include/video. This file usually
76  * also includes register information. That allows other driver subsystems
77  * and userland applications the ability to use the same header file to
78  * avoid duplicate work and easy porting of software.
79  */
80 struct xxx_par;
81 
82 /*
83  * Here we define the default structs fb_fix_screeninfo and fb_var_screeninfo
84  * if we don't use modedb. If we do use modedb see xxxfb_init how to use it
85  * to get a fb_var_screeninfo. Otherwise define a default var as well.
86  */
87 static const struct fb_fix_screeninfo xxxfb_fix = {
88 	.id =		"FB's name",
89 	.type =		FB_TYPE_PACKED_PIXELS,
90 	.visual =	FB_VISUAL_PSEUDOCOLOR,
91 	.xpanstep =	1,
92 	.ypanstep =	1,
93 	.ywrapstep =	1,
94 	.accel =	FB_ACCEL_NONE,
95 };
96 
97     /*
98      * 	Modern graphical hardware not only supports pipelines but some
99      *  also support multiple monitors where each display can have its
100      *  its own unique data. In this case each display could be
101      *  represented by a separate framebuffer device thus a separate
102      *  struct fb_info. Now the struct xxx_par represents the graphics
103      *  hardware state thus only one exist per card. In this case the
104      *  struct xxx_par for each graphics card would be shared between
105      *  every struct fb_info that represents a framebuffer on that card.
106      *  This allows when one display changes it video resolution (info->var)
107      *  the other displays know instantly. Each display can always be
108      *  aware of the entire hardware state that affects it because they share
109      *  the same xxx_par struct. The other side of the coin is multiple
110      *  graphics cards that pass data around until it is finally displayed
111      *  on one monitor. Such examples are the voodoo 1 cards and high end
112      *  NUMA graphics servers. For this case we have a bunch of pars, each
113      *  one that represents a graphics state, that belong to one struct
114      *  fb_info. Their you would want to have *par point to a array of device
115      *  states and have each struct fb_ops function deal with all those
116      *  states. I hope this covers every possible hardware design. If not
117      *  feel free to send your ideas at jsimmons@users.sf.net
118      */
119 
120     /*
121      *  If your driver supports multiple boards or it supports multiple
122      *  framebuffers, you should make these arrays, or allocate them
123      *  dynamically using framebuffer_alloc() and free them with
124      *  framebuffer_release().
125      */
126 static struct fb_info info;
127 
128     /*
129      * Each one represents the state of the hardware. Most hardware have
130      * just one hardware state. These here represent the default state(s).
131      */
132 static struct xxx_par __initdata current_par;
133 
134 int xxxfb_init(void);
135 
136 /**
137  *	xxxfb_open - Optional function. Called when the framebuffer is
138  *		     first accessed.
139  *	@info: frame buffer structure that represents a single frame buffer
140  *	@user: tell us if the userland (value=1) or the console is accessing
141  *	       the framebuffer.
142  *
143  *	This function is the first function called in the framebuffer api.
144  *	Usually you don't need to provide this function. The case where it
145  *	is used is to change from a text mode hardware state to a graphics
146  * 	mode state.
147  *
148  *	Returns negative errno on error, or zero on success.
149  */
150 static int xxxfb_open(struct fb_info *info, int user)
151 {
152     return 0;
153 }
154 
155 /**
156  *	xxxfb_release - Optional function. Called when the framebuffer
157  *			device is closed.
158  *	@info: frame buffer structure that represents a single frame buffer
159  *	@user: tell us if the userland (value=1) or the console is accessing
160  *	       the framebuffer.
161  *
162  *	Thus function is called when we close /dev/fb or the framebuffer
163  *	console system is released. Usually you don't need this function.
164  *	The case where it is usually used is to go from a graphics state
165  *	to a text mode state.
166  *
167  *	Returns negative errno on error, or zero on success.
168  */
169 static int xxxfb_release(struct fb_info *info, int user)
170 {
171     return 0;
172 }
173 
174 /**
175  *      xxxfb_check_var - Optional function. Validates a var passed in.
176  *      @var: frame buffer variable screen structure
177  *      @info: frame buffer structure that represents a single frame buffer
178  *
179  *	Checks to see if the hardware supports the state requested by
180  *	var passed in. This function does not alter the hardware state!!!
181  *	This means the data stored in struct fb_info and struct xxx_par do
182  *      not change. This includes the var inside of struct fb_info.
183  *	Do NOT change these. This function can be called on its own if we
184  *	intent to only test a mode and not actually set it. The stuff in
185  *	modedb.c is a example of this. If the var passed in is slightly
186  *	off by what the hardware can support then we alter the var PASSED in
187  *	to what we can do.
188  *
189  *      For values that are off, this function must round them _up_ to the
190  *      next value that is supported by the hardware.  If the value is
191  *      greater than the highest value supported by the hardware, then this
192  *      function must return -EINVAL.
193  *
194  *      Exception to the above rule:  Some drivers have a fixed mode, ie,
195  *      the hardware is already set at boot up, and cannot be changed.  In
196  *      this case, it is more acceptable that this function just return
197  *      a copy of the currently working var (info->var). Better is to not
198  *      implement this function, as the upper layer will do the copying
199  *      of the current var for you.
200  *
201  *      Note:  This is the only function where the contents of var can be
202  *      freely adjusted after the driver has been registered. If you find
203  *      that you have code outside of this function that alters the content
204  *      of var, then you are doing something wrong.  Note also that the
205  *      contents of info->var must be left untouched at all times after
206  *      driver registration.
207  *
208  *	Returns negative errno on error, or zero on success.
209  */
210 static int xxxfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
211 {
212     /* ... */
213     return 0;
214 }
215 
216 /**
217  *      xxxfb_set_par - Optional function. Alters the hardware state.
218  *      @info: frame buffer structure that represents a single frame buffer
219  *
220  *	Using the fb_var_screeninfo in fb_info we set the resolution of the
221  *	this particular framebuffer. This function alters the par AND the
222  *	fb_fix_screeninfo stored in fb_info. It doesn't not alter var in
223  *	fb_info since we are using that data. This means we depend on the
224  *	data in var inside fb_info to be supported by the hardware.
225  *
226  *      This function is also used to recover/restore the hardware to a
227  *      known working state.
228  *
229  *	xxxfb_check_var is always called before xxxfb_set_par to ensure that
230  *      the contents of var is always valid.
231  *
232  *	Again if you can't change the resolution you don't need this function.
233  *
234  *      However, even if your hardware does not support mode changing,
235  *      a set_par might be needed to at least initialize the hardware to
236  *      a known working state, especially if it came back from another
237  *      process that also modifies the same hardware, such as X.
238  *
239  *      If this is the case, a combination such as the following should work:
240  *
241  *      static int xxxfb_check_var(struct fb_var_screeninfo *var,
242  *                                struct fb_info *info)
243  *      {
244  *              *var = info->var;
245  *              return 0;
246  *      }
247  *
248  *      static int xxxfb_set_par(struct fb_info *info)
249  *      {
250  *              init your hardware here
251  *      }
252  *
253  *	Returns negative errno on error, or zero on success.
254  */
255 static int xxxfb_set_par(struct fb_info *info)
256 {
257     struct xxx_par *par = info->par;
258     /* ... */
259     return 0;
260 }
261 
262 /**
263  *  	xxxfb_setcolreg - Optional function. Sets a color register.
264  *      @regno: Which register in the CLUT we are programming
265  *      @red: The red value which can be up to 16 bits wide
266  *	@green: The green value which can be up to 16 bits wide
267  *	@blue:  The blue value which can be up to 16 bits wide.
268  *	@transp: If supported, the alpha value which can be up to 16 bits wide.
269  *      @info: frame buffer info structure
270  *
271  *  	Set a single color register. The values supplied have a 16 bit
272  *  	magnitude which needs to be scaled in this function for the hardware.
273  *	Things to take into consideration are how many color registers, if
274  *	any, are supported with the current color visual. With truecolor mode
275  *	no color palettes are supported. Here a pseudo palette is created
276  *	which we store the value in pseudo_palette in struct fb_info. For
277  *	pseudocolor mode we have a limited color palette. To deal with this
278  *	we can program what color is displayed for a particular pixel value.
279  *	DirectColor is similar in that we can program each color field. If
280  *	we have a static colormap we don't need to implement this function.
281  *
282  *	Returns negative errno on error, or zero on success.
283  */
284 static int xxxfb_setcolreg(unsigned regno, unsigned red, unsigned green,
285 			   unsigned blue, unsigned transp,
286 			   struct fb_info *info)
287 {
288     if (regno >= 256)  /* no. of hw registers */
289        return -EINVAL;
290     /*
291      * Program hardware... do anything you want with transp
292      */
293 
294     /* grayscale works only partially under directcolor */
295     if (info->var.grayscale) {
296        /* grayscale = 0.30*R + 0.59*G + 0.11*B */
297        red = green = blue = (red * 77 + green * 151 + blue * 28) >> 8;
298     }
299 
300     /* Directcolor:
301      *   var->{color}.offset contains start of bitfield
302      *   var->{color}.length contains length of bitfield
303      *   {hardwarespecific} contains width of DAC
304      *   pseudo_palette[X] is programmed to (X << red.offset) |
305      *                                      (X << green.offset) |
306      *                                      (X << blue.offset)
307      *   RAMDAC[X] is programmed to (red, green, blue)
308      *   color depth = SUM(var->{color}.length)
309      *
310      * Pseudocolor:
311      *    var->{color}.offset is 0 unless the palette index takes less than
312      *                        bits_per_pixel bits and is stored in the upper
313      *                        bits of the pixel value
314      *    var->{color}.length is set so that 1 << length is the number of
315      *                        available palette entries
316      *    pseudo_palette is not used
317      *    RAMDAC[X] is programmed to (red, green, blue)
318      *    color depth = var->{color}.length
319      *
320      * Static pseudocolor:
321      *    same as Pseudocolor, but the RAMDAC is not programmed (read-only)
322      *
323      * Mono01/Mono10:
324      *    Has only 2 values, black on white or white on black (fg on bg),
325      *    var->{color}.offset is 0
326      *    white = (1 << var->{color}.length) - 1, black = 0
327      *    pseudo_palette is not used
328      *    RAMDAC does not exist
329      *    color depth is always 2
330      *
331      * Truecolor:
332      *    does not use RAMDAC (usually has 3 of them).
333      *    var->{color}.offset contains start of bitfield
334      *    var->{color}.length contains length of bitfield
335      *    pseudo_palette is programmed to (red << red.offset) |
336      *                                    (green << green.offset) |
337      *                                    (blue << blue.offset) |
338      *                                    (transp << transp.offset)
339      *    RAMDAC does not exist
340      *    color depth = SUM(var->{color}.length})
341      *
342      *  The color depth is used by fbcon for choosing the logo and also
343      *  for color palette transformation if color depth < 4
344      *
345      *  As can be seen from the above, the field bits_per_pixel is _NOT_
346      *  a criteria for describing the color visual.
347      *
348      *  A common mistake is assuming that bits_per_pixel <= 8 is pseudocolor,
349      *  and higher than that, true/directcolor.  This is incorrect, one needs
350      *  to look at the fix->visual.
351      *
352      *  Another common mistake is using bits_per_pixel to calculate the color
353      *  depth.  The bits_per_pixel field does not directly translate to color
354      *  depth. You have to compute for the color depth (using the color
355      *  bitfields) and fix->visual as seen above.
356      */
357 
358     /*
359      * This is the point where the color is converted to something that
360      * is acceptable by the hardware.
361      */
362 #define CNVT_TOHW(val,width) ((((val)<<(width))+0x7FFF-(val))>>16)
363     red = CNVT_TOHW(red, info->var.red.length);
364     green = CNVT_TOHW(green, info->var.green.length);
365     blue = CNVT_TOHW(blue, info->var.blue.length);
366     transp = CNVT_TOHW(transp, info->var.transp.length);
367 #undef CNVT_TOHW
368     /*
369      * This is the point where the function feeds the color to the hardware
370      * palette after converting the colors to something acceptable by
371      * the hardware. Note, only FB_VISUAL_DIRECTCOLOR and
372      * FB_VISUAL_PSEUDOCOLOR visuals need to write to the hardware palette.
373      * If you have code that writes to the hardware CLUT, and it's not
374      * any of the above visuals, then you are doing something wrong.
375      */
376     if (info->fix.visual == FB_VISUAL_DIRECTCOLOR ||
377 	info->fix.visual == FB_VISUAL_TRUECOLOR)
378 	    write_{red|green|blue|transp}_to_clut();
379 
380     /* This is the point were you need to fill up the contents of
381      * info->pseudo_palette. This structure is used _only_ by fbcon, thus
382      * it only contains 16 entries to match the number of colors supported
383      * by the console. The pseudo_palette is used only if the visual is
384      * in directcolor or truecolor mode.  With other visuals, the
385      * pseudo_palette is not used. (This might change in the future.)
386      *
387      * The contents of the pseudo_palette is in raw pixel format.  Ie, each
388      * entry can be written directly to the framebuffer without any conversion.
389      * The pseudo_palette is (void *).  However, if using the generic
390      * drawing functions (cfb_imageblit, cfb_fillrect), the pseudo_palette
391      * must be casted to (u32 *) _regardless_ of the bits per pixel. If the
392      * driver is using its own drawing functions, then it can use whatever
393      * size it wants.
394      */
395     if (info->fix.visual == FB_VISUAL_TRUECOLOR ||
396 	info->fix.visual == FB_VISUAL_DIRECTCOLOR) {
397 	    u32 v;
398 
399 	    if (regno >= 16)
400 		    return -EINVAL;
401 
402 	    v = (red << info->var.red.offset) |
403 		    (green << info->var.green.offset) |
404 		    (blue << info->var.blue.offset) |
405 		    (transp << info->var.transp.offset);
406 
407 	    ((u32*)(info->pseudo_palette))[regno] = v;
408     }
409 
410     /* ... */
411     return 0;
412 }
413 
414 /**
415  *      xxxfb_pan_display - NOT a required function. Pans the display.
416  *      @var: frame buffer variable screen structure
417  *      @info: frame buffer structure that represents a single frame buffer
418  *
419  *	Pan (or wrap, depending on the `vmode' field) the display using the
420  *  	`xoffset' and `yoffset' fields of the `var' structure.
421  *  	If the values don't fit, return -EINVAL.
422  *
423  *      Returns negative errno on error, or zero on success.
424  */
425 static int xxxfb_pan_display(struct fb_var_screeninfo *var,
426 			     struct fb_info *info)
427 {
428     /*
429      * If your hardware does not support panning, _do_ _not_ implement this
430      * function. Creating a dummy function will just confuse user apps.
431      */
432 
433     /*
434      * Note that even if this function is fully functional, a setting of
435      * 0 in both xpanstep and ypanstep means that this function will never
436      * get called.
437      */
438 
439     /* ... */
440     return 0;
441 }
442 
443 /**
444  *      xxxfb_blank - NOT a required function. Blanks the display.
445  *      @blank_mode: the blank mode we want.
446  *      @info: frame buffer structure that represents a single frame buffer
447  *
448  *      Blank the screen if blank_mode != FB_BLANK_UNBLANK, else unblank.
449  *      Return 0 if blanking succeeded, != 0 if un-/blanking failed due to
450  *      e.g. a video mode which doesn't support it.
451  *
452  *      Implements VESA suspend and powerdown modes on hardware that supports
453  *      disabling hsync/vsync:
454  *
455  *      FB_BLANK_NORMAL = display is blanked, syncs are on.
456  *      FB_BLANK_HSYNC_SUSPEND = hsync off
457  *      FB_BLANK_VSYNC_SUSPEND = vsync off
458  *      FB_BLANK_POWERDOWN =  hsync and vsync off
459  *
460  *      If implementing this function, at least support FB_BLANK_UNBLANK.
461  *      Return !0 for any modes that are unimplemented.
462  *
463  */
464 static int xxxfb_blank(int blank_mode, struct fb_info *info)
465 {
466     /* ... */
467     return 0;
468 }
469 
470 /* ------------ Accelerated Functions --------------------- */
471 
472 /*
473  * We provide our own functions if we have hardware acceleration
474  * or non packed pixel format layouts. If we have no hardware
475  * acceleration, we can use a generic unaccelerated function. If using
476  * a pack pixel format just use the functions in cfb_*.c. Each file
477  * has one of the three different accel functions we support.
478  */
479 
480 /**
481  *      xxxfb_fillrect - REQUIRED function. Can use generic routines if
482  *		 	 non acclerated hardware and packed pixel based.
483  *			 Draws a rectangle on the screen.
484  *
485  *      @info: frame buffer structure that represents a single frame buffer
486  *	@region: The structure representing the rectangular region we
487  *		 wish to draw to.
488  *
489  *	This drawing operation places/removes a retangle on the screen
490  *	depending on the rastering operation with the value of color which
491  *	is in the current color depth format.
492  */
493 void xxxfb_fillrect(struct fb_info *p, const struct fb_fillrect *region)
494 {
495 /*	Meaning of struct fb_fillrect
496  *
497  *	@dx: The x and y corrdinates of the upper left hand corner of the
498  *	@dy: area we want to draw to.
499  *	@width: How wide the rectangle is we want to draw.
500  *	@height: How tall the rectangle is we want to draw.
501  *	@color:	The color to fill in the rectangle with.
502  *	@rop: The raster operation. We can draw the rectangle with a COPY
503  *	      of XOR which provides erasing effect.
504  */
505 }
506 
507 /**
508  *      xxxfb_copyarea - REQUIRED function. Can use generic routines if
509  *                       non acclerated hardware and packed pixel based.
510  *                       Copies one area of the screen to another area.
511  *
512  *      @info: frame buffer structure that represents a single frame buffer
513  *      @area: Structure providing the data to copy the framebuffer contents
514  *	       from one region to another.
515  *
516  *      This drawing operation copies a rectangular area from one area of the
517  *	screen to another area.
518  */
519 void xxxfb_copyarea(struct fb_info *p, const struct fb_copyarea *area)
520 {
521 /*
522  *      @dx: The x and y coordinates of the upper left hand corner of the
523  *	@dy: destination area on the screen.
524  *      @width: How wide the rectangle is we want to copy.
525  *      @height: How tall the rectangle is we want to copy.
526  *      @sx: The x and y coordinates of the upper left hand corner of the
527  *      @sy: source area on the screen.
528  */
529 }
530 
531 
532 /**
533  *      xxxfb_imageblit - REQUIRED function. Can use generic routines if
534  *                        non acclerated hardware and packed pixel based.
535  *                        Copies a image from system memory to the screen.
536  *
537  *      @info: frame buffer structure that represents a single frame buffer
538  *	@image:	structure defining the image.
539  *
540  *      This drawing operation draws a image on the screen. It can be a
541  *	mono image (needed for font handling) or a color image (needed for
542  *	tux).
543  */
544 void xxxfb_imageblit(struct fb_info *p, const struct fb_image *image)
545 {
546 /*
547  *      @dx: The x and y coordinates of the upper left hand corner of the
548  *	@dy: destination area to place the image on the screen.
549  *      @width: How wide the image is we want to copy.
550  *      @height: How tall the image is we want to copy.
551  *      @fg_color: For mono bitmap images this is color data for
552  *      @bg_color: the foreground and background of the image to
553  *		   write directly to the frmaebuffer.
554  *	@depth:	How many bits represent a single pixel for this image.
555  *	@data: The actual data used to construct the image on the display.
556  *	@cmap: The colormap used for color images.
557  */
558 
559 /*
560  * The generic function, cfb_imageblit, expects that the bitmap scanlines are
561  * padded to the next byte.  Most hardware accelerators may require padding to
562  * the next u16 or the next u32.  If that is the case, the driver can specify
563  * this by setting info->pixmap.scan_align = 2 or 4.  See a more
564  * comprehensive description of the pixmap below.
565  */
566 }
567 
568 /**
569  *	xxxfb_cursor - 	OPTIONAL. If your hardware lacks support
570  *			for a cursor, leave this field NULL.
571  *
572  *      @info: frame buffer structure that represents a single frame buffer
573  *	@cursor: structure defining the cursor to draw.
574  *
575  *      This operation is used to set or alter the properities of the
576  *	cursor.
577  *
578  *	Returns negative errno on error, or zero on success.
579  */
580 int xxxfb_cursor(struct fb_info *info, struct fb_cursor *cursor)
581 {
582 /*
583  *      @set: 	Which fields we are altering in struct fb_cursor
584  *	@enable: Disable or enable the cursor
585  *      @rop: 	The bit operation we want to do.
586  *      @mask:  This is the cursor mask bitmap.
587  *      @dest:  A image of the area we are going to display the cursor.
588  *		Used internally by the driver.
589  *      @hot:	The hot spot.
590  *	@image:	The actual data for the cursor image.
591  *
592  *      NOTES ON FLAGS (cursor->set):
593  *
594  *      FB_CUR_SETIMAGE - the cursor image has changed (cursor->image.data)
595  *      FB_CUR_SETPOS   - the cursor position has changed (cursor->image.dx|dy)
596  *      FB_CUR_SETHOT   - the cursor hot spot has changed (cursor->hot.dx|dy)
597  *      FB_CUR_SETCMAP  - the cursor colors has changed (cursor->fg_color|bg_color)
598  *      FB_CUR_SETSHAPE - the cursor bitmask has changed (cursor->mask)
599  *      FB_CUR_SETSIZE  - the cursor size has changed (cursor->width|height)
600  *      FB_CUR_SETALL   - everything has changed
601  *
602  *      NOTES ON ROPs (cursor->rop, Raster Operation)
603  *
604  *      ROP_XOR         - cursor->image.data XOR cursor->mask
605  *      ROP_COPY        - curosr->image.data AND cursor->mask
606  *
607  *      OTHER NOTES:
608  *
609  *      - fbcon only supports a 2-color cursor (cursor->image.depth = 1)
610  *      - The fb_cursor structure, @cursor, _will_ always contain valid
611  *        fields, whether any particular bitfields in cursor->set is set
612  *        or not.
613  */
614 }
615 
616 /**
617  *	xxxfb_sync - NOT a required function. Normally the accel engine
618  *		     for a graphics card take a specific amount of time.
619  *		     Often we have to wait for the accelerator to finish
620  *		     its operation before we can write to the framebuffer
621  *		     so we can have consistent display output.
622  *
623  *      @info: frame buffer structure that represents a single frame buffer
624  *
625  *      If the driver has implemented its own hardware-based drawing function,
626  *      implementing this function is highly recommended.
627  */
628 int xxxfb_sync(struct fb_info *info)
629 {
630 	return 0;
631 }
632 
633     /*
634      *  Frame buffer operations
635      */
636 
637 static const struct fb_ops xxxfb_ops = {
638 	.owner		= THIS_MODULE,
639 	.fb_open	= xxxfb_open,
640 	.fb_read	= xxxfb_read,
641 	.fb_write	= xxxfb_write,
642 	.fb_release	= xxxfb_release,
643 	.fb_check_var	= xxxfb_check_var,
644 	.fb_set_par	= xxxfb_set_par,
645 	.fb_setcolreg	= xxxfb_setcolreg,
646 	.fb_blank	= xxxfb_blank,
647 	.fb_pan_display	= xxxfb_pan_display,
648 	.fb_fillrect	= xxxfb_fillrect, 	/* Needed !!! */
649 	.fb_copyarea	= xxxfb_copyarea,	/* Needed !!! */
650 	.fb_imageblit	= xxxfb_imageblit,	/* Needed !!! */
651 	.fb_cursor	= xxxfb_cursor,		/* Optional !!! */
652 	.fb_sync	= xxxfb_sync,
653 	.fb_ioctl	= xxxfb_ioctl,
654 	.fb_mmap	= xxxfb_mmap,
655 };
656 
657 /* ------------------------------------------------------------------------- */
658 
659     /*
660      *  Initialization
661      */
662 
663 /* static int __init xxfb_probe (struct platform_device *pdev) -- for platform devs */
664 static int xxxfb_probe(struct pci_dev *dev, const struct pci_device_id *ent)
665 {
666     struct fb_info *info;
667     struct xxx_par *par;
668     struct device *device = &dev->dev; /* or &pdev->dev */
669     int cmap_len, retval;
670 
671     /*
672      * Dynamically allocate info and par
673      */
674     info = framebuffer_alloc(sizeof(struct xxx_par), device);
675 
676     if (!info) {
677 	    /* goto error path */
678     }
679 
680     par = info->par;
681 
682     /*
683      * Here we set the screen_base to the virtual memory address
684      * for the framebuffer. Usually we obtain the resource address
685      * from the bus layer and then translate it to virtual memory
686      * space via ioremap. Consult ioport.h.
687      */
688     info->screen_base = framebuffer_virtual_memory;
689     info->fbops = &xxxfb_ops;
690     info->fix = xxxfb_fix;
691     info->pseudo_palette = pseudo_palette; /* The pseudopalette is an
692 					    * 16-member array
693 					    */
694     /*
695      * Set up flags to indicate what sort of acceleration your
696      * driver can provide (pan/wrap/copyarea/etc.) and whether it
697      * is a module -- see FBINFO_* in include/linux/fb.h
698      *
699      * If your hardware can support any of the hardware accelerated functions
700      * fbcon performance will improve if info->flags is set properly.
701      *
702      * FBINFO_HWACCEL_COPYAREA - hardware moves
703      * FBINFO_HWACCEL_FILLRECT - hardware fills
704      * FBINFO_HWACCEL_IMAGEBLIT - hardware mono->color expansion
705      * FBINFO_HWACCEL_YPAN - hardware can pan display in y-axis
706      * FBINFO_HWACCEL_YWRAP - hardware can wrap display in y-axis
707      * FBINFO_HWACCEL_DISABLED - supports hardware accels, but disabled
708      * FBINFO_READS_FAST - if set, prefer moves over mono->color expansion
709      * FBINFO_MISC_TILEBLITTING - hardware can do tile blits
710      *
711      * NOTE: These are for fbcon use only.
712      */
713     info->flags = FBINFO_DEFAULT;
714 
715 /********************* This stage is optional ******************************/
716      /*
717      * The struct pixmap is a scratch pad for the drawing functions. This
718      * is where the monochrome bitmap is constructed by the higher layers
719      * and then passed to the accelerator.  For drivers that uses
720      * cfb_imageblit, you can skip this part.  For those that have a more
721      * rigorous requirement, this stage is needed
722      */
723 
724     /* PIXMAP_SIZE should be small enough to optimize drawing, but not
725      * large enough that memory is wasted.  A safe size is
726      * (max_xres * max_font_height/8). max_xres is driver dependent,
727      * max_font_height is 32.
728      */
729     info->pixmap.addr = kmalloc(PIXMAP_SIZE, GFP_KERNEL);
730     if (!info->pixmap.addr) {
731 	    /* goto error */
732     }
733 
734     info->pixmap.size = PIXMAP_SIZE;
735 
736     /*
737      * FB_PIXMAP_SYSTEM - memory is in system ram
738      * FB_PIXMAP_IO     - memory is iomapped
739      * FB_PIXMAP_SYNC   - if set, will call fb_sync() per access to pixmap,
740      *                    usually if FB_PIXMAP_IO is set.
741      *
742      * Currently, FB_PIXMAP_IO is unimplemented.
743      */
744     info->pixmap.flags = FB_PIXMAP_SYSTEM;
745 
746     /*
747      * scan_align is the number of padding for each scanline.  It is in bytes.
748      * Thus for accelerators that need padding to the next u32, put 4 here.
749      */
750     info->pixmap.scan_align = 4;
751 
752     /*
753      * buf_align is the amount to be padded for the buffer. For example,
754      * the i810fb needs a scan_align of 2 but expects it to be fed with
755      * dwords, so a buf_align = 4 is required.
756      */
757     info->pixmap.buf_align = 4;
758 
759     /* access_align is how many bits can be accessed from the framebuffer
760      * ie. some epson cards allow 16-bit access only.  Most drivers will
761      * be safe with u32 here.
762      *
763      * NOTE: This field is currently unused.
764      */
765     info->pixmap.access_align = 32;
766 /***************************** End optional stage ***************************/
767 
768     /*
769      * This should give a reasonable default video mode. The following is
770      * done when we can set a video mode.
771      */
772     if (!mode_option)
773 	mode_option = "640x480@60";
774 
775     retval = fb_find_mode(&info->var, info, mode_option, NULL, 0, NULL, 8);
776 
777     if (!retval || retval == 4)
778 	return -EINVAL;
779 
780     /* This has to be done! */
781     if (fb_alloc_cmap(&info->cmap, cmap_len, 0))
782 	return -ENOMEM;
783 
784     /*
785      * The following is done in the case of having hardware with a static
786      * mode. If we are setting the mode ourselves we don't call this.
787      */
788     info->var = xxxfb_var;
789 
790     /*
791      * For drivers that can...
792      */
793     xxxfb_check_var(&info->var, info);
794 
795     /*
796      * Does a call to fb_set_par() before register_framebuffer needed?  This
797      * will depend on you and the hardware.  If you are sure that your driver
798      * is the only device in the system, a call to fb_set_par() is safe.
799      *
800      * Hardware in x86 systems has a VGA core.  Calling set_par() at this
801      * point will corrupt the VGA console, so it might be safer to skip a
802      * call to set_par here and just allow fbcon to do it for you.
803      */
804     /* xxxfb_set_par(info); */
805 
806     if (register_framebuffer(info) < 0) {
807 	fb_dealloc_cmap(&info->cmap);
808 	return -EINVAL;
809     }
810     fb_info(info, "%s frame buffer device\n", info->fix.id);
811     pci_set_drvdata(dev, info); /* or platform_set_drvdata(pdev, info) */
812     return 0;
813 }
814 
815     /*
816      *  Cleanup
817      */
818 /* static void xxxfb_remove(struct platform_device *pdev) */
819 static void xxxfb_remove(struct pci_dev *dev)
820 {
821 	struct fb_info *info = pci_get_drvdata(dev);
822 	/* or platform_get_drvdata(pdev); */
823 
824 	if (info) {
825 		unregister_framebuffer(info);
826 		fb_dealloc_cmap(&info->cmap);
827 		/* ... */
828 		framebuffer_release(info);
829 	}
830 }
831 
832 #ifdef CONFIG_PCI
833 #ifdef CONFIG_PM
834 /**
835  *	xxxfb_suspend - Optional but recommended function. Suspend the device.
836  *	@dev: PCI device
837  *	@msg: the suspend event code.
838  *
839  *      See Documentation/driver-api/pm/devices.rst for more information
840  */
841 static int xxxfb_suspend(struct pci_dev *dev, pm_message_t msg)
842 {
843 	struct fb_info *info = pci_get_drvdata(dev);
844 	struct xxxfb_par *par = info->par;
845 
846 	/* suspend here */
847 	return 0;
848 }
849 
850 /**
851  *	xxxfb_resume - Optional but recommended function. Resume the device.
852  *	@dev: PCI device
853  *
854  *      See Documentation/driver-api/pm/devices.rst for more information
855  */
856 static int xxxfb_resume(struct pci_dev *dev)
857 {
858 	struct fb_info *info = pci_get_drvdata(dev);
859 	struct xxxfb_par *par = info->par;
860 
861 	/* resume here */
862 	return 0;
863 }
864 #else
865 #define xxxfb_suspend NULL
866 #define xxxfb_resume NULL
867 #endif /* CONFIG_PM */
868 
869 static const struct pci_device_id xxxfb_id_table[] = {
870 	{ PCI_VENDOR_ID_XXX, PCI_DEVICE_ID_XXX,
871 	  PCI_ANY_ID, PCI_ANY_ID, PCI_BASE_CLASS_DISPLAY << 16,
872 	  PCI_CLASS_MASK, 0 },
873 	{ 0, }
874 };
875 
876 /* For PCI drivers */
877 static struct pci_driver xxxfb_driver = {
878 	.name =		"xxxfb",
879 	.id_table =	xxxfb_id_table,
880 	.probe =	xxxfb_probe,
881 	.remove =	xxxfb_remove,
882 	.suspend =      xxxfb_suspend, /* optional but recommended */
883 	.resume =       xxxfb_resume,  /* optional but recommended */
884 };
885 
886 MODULE_DEVICE_TABLE(pci, xxxfb_id_table);
887 
888 int __init xxxfb_init(void)
889 {
890 	/*
891 	 *  For kernel boot options (in 'video=xxxfb:<options>' format)
892 	 */
893 #ifndef MODULE
894 	char *option = NULL;
895 
896 	if (fb_get_options("xxxfb", &option))
897 		return -ENODEV;
898 	xxxfb_setup(option);
899 #endif
900 
901 	return pci_register_driver(&xxxfb_driver);
902 }
903 
904 static void __exit xxxfb_exit(void)
905 {
906 	pci_unregister_driver(&xxxfb_driver);
907 }
908 #else /* non PCI, platform drivers */
909 #include <linux/platform_device.h>
910 /* for platform devices */
911 
912 #ifdef CONFIG_PM
913 /**
914  *	xxxfb_suspend - Optional but recommended function. Suspend the device.
915  *	@dev: platform device
916  *	@msg: the suspend event code.
917  *
918  *      See Documentation/driver-api/pm/devices.rst for more information
919  */
920 static int xxxfb_suspend(struct platform_device *dev, pm_message_t msg)
921 {
922 	struct fb_info *info = platform_get_drvdata(dev);
923 	struct xxxfb_par *par = info->par;
924 
925 	/* suspend here */
926 	return 0;
927 }
928 
929 /**
930  *	xxxfb_resume - Optional but recommended function. Resume the device.
931  *	@dev: platform device
932  *
933  *      See Documentation/driver-api/pm/devices.rst for more information
934  */
935 static int xxxfb_resume(struct platform_dev *dev)
936 {
937 	struct fb_info *info = platform_get_drvdata(dev);
938 	struct xxxfb_par *par = info->par;
939 
940 	/* resume here */
941 	return 0;
942 }
943 #else
944 #define xxxfb_suspend NULL
945 #define xxxfb_resume NULL
946 #endif /* CONFIG_PM */
947 
948 static struct platform_device_driver xxxfb_driver = {
949 	.probe = xxxfb_probe,
950 	.remove = xxxfb_remove,
951 	.suspend = xxxfb_suspend, /* optional but recommended */
952 	.resume = xxxfb_resume,   /* optional but recommended */
953 	.driver = {
954 		.name = "xxxfb",
955 	},
956 };
957 
958 static struct platform_device *xxxfb_device;
959 
960 #ifndef MODULE
961     /*
962      *  Setup
963      */
964 
965 /*
966  * Only necessary if your driver takes special options,
967  * otherwise we fall back on the generic fb_setup().
968  */
969 int __init xxxfb_setup(char *options)
970 {
971     /* Parse user specified options (`video=xxxfb:') */
972 }
973 #endif /* MODULE */
974 
975 static int __init xxxfb_init(void)
976 {
977 	int ret;
978 	/*
979 	 *  For kernel boot options (in 'video=xxxfb:<options>' format)
980 	 */
981 #ifndef MODULE
982 	char *option = NULL;
983 
984 	if (fb_get_options("xxxfb", &option))
985 		return -ENODEV;
986 	xxxfb_setup(option);
987 #endif
988 	ret = platform_driver_register(&xxxfb_driver);
989 
990 	if (!ret) {
991 		xxxfb_device = platform_device_register_simple("xxxfb", 0,
992 								NULL, 0);
993 
994 		if (IS_ERR(xxxfb_device)) {
995 			platform_driver_unregister(&xxxfb_driver);
996 			ret = PTR_ERR(xxxfb_device);
997 		}
998 	}
999 
1000 	return ret;
1001 }
1002 
1003 static void __exit xxxfb_exit(void)
1004 {
1005 	platform_device_unregister(xxxfb_device);
1006 	platform_driver_unregister(&xxxfb_driver);
1007 }
1008 #endif /* CONFIG_PCI */
1009 
1010 /* ------------------------------------------------------------------------- */
1011 
1012 
1013     /*
1014      *  Modularization
1015      */
1016 
1017 module_init(xxxfb_init);
1018 module_exit(xxxfb_exit);
1019 
1020 MODULE_LICENSE("GPL");
1021