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[PATCH] skeletonfb: Documentation update

Browse source 
Update skeletonfb so it reflects recent (and somewhat old) changes of the
framebuffer layer.

Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Antonino A. Daplas 2006-01-09 20:53:34 -08:00 • committed by Linus Torvalds
parent c549dc6422
commit d911233fe6
1 changed files with 381 additions and 97 deletions
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510
drivers/video/skeletonfb.c
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@ -115,7 +115,8 @@ static struct fb_fix_screeninfo xxxfb_fix __initdata = {
/*
* If your driver supports multiple boards or it supports multiple
* framebuffers, you should make these arrays, or allocate them
* dynamically (using kmalloc()).
* dynamically using framebuffer_alloc() and free them with
* framebuffer_release().
*/
static struct fb_info info;
@ -179,18 +180,31 @@ static int xxxfb_release(const struct fb_info *info, int user)
* 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
* a -EINVAL will be returned by the upper layers. You don't need to
* implement this function then. If you hardware doesn't support
* changing the resolution then this function is not needed. In this
* case the driver woudl just provide a var that represents the static
* state the screen is 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)
{
const struct xxx_par *par = (const struct xxx_par *) info->par;
/* ... */
return 0;
}
@ -204,14 +218,39 @@ static int xxxfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
* 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.
*
* 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 = (struct xxx_par *) info->par;
struct xxx_par *par = info->par;
/* ... */
return 0;
}
@ -258,45 +297,97 @@ static int xxxfb_setcolreg(unsigned regno, unsigned red, unsigned green,
* 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)
* 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:
* 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)
* var->{color}.length contains width of DAC or the number of unique
* colors available (color depth)
* 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
* cmap is programmed to (red << red.offset) | (green << green.offset) |
* (blue << blue.offset) | (transp << transp.offset)
* 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)
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) {
/*
* 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)
@ -307,21 +398,9 @@ static int xxxfb_setcolreg(unsigned regno, unsigned red, unsigned green,
(blue << info->var.blue.offset) |
(transp << info->var.transp.offset);
switch (info->var.bits_per_pixel) {
case 8:
/* Yes some hand held devices have this. */
((u8*)(info->pseudo_palette))[regno] = v;
break;
case 16:
((u16*)(info->pseudo_palette))[regno] = v;
break;
case 24:
case 32:
((u32*)(info->pseudo_palette))[regno] = v;
break;
}
return 0;
}
/* ... */
return 0;
}
@ -340,6 +419,17 @@ static int xxxfb_setcolreg(unsigned regno, unsigned red, unsigned green,
static int xxxfb_pan_display(struct fb_var_screeninfo *var,
const 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;
}
@ -349,15 +439,20 @@ static int xxxfb_pan_display(struct fb_var_screeninfo *var,
* @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
* 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.
*
* Returns negative errno on error, or zero on success.
* 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, const struct fb_info *info)
@ -454,6 +549,14 @@ void xxxfb_imageblit(struct fb_info *p, const struct fb_image *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.
*/
}
/**
@ -517,6 +620,7 @@ int xxxfb_cursor(struct fb_info *info, struct fb_cursor *cursor)
*/
void xxxfb_rotate(struct fb_info *info, int angle)
{
/* Will be deprecated */
}
/**
@ -540,6 +644,9 @@ void xxxfb_poll(struct fb_info *info, poll_table *wait)
* 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.
*/
void xxxfb_sync(struct fb_info *info)
{
@ -549,10 +656,191 @@ void xxxfb_sync(struct fb_info *info)
* Initialization
*/
int __init xxxfb_init(void)
/* static int __init xxfb_probe (struct device *device) -- for platform devs */
static int __init xxxfb_probe(struct pci_dev *dev,
const_struct pci_device_id *ent)
{
struct fb_info *info;
struct xxx_par *par;
struct device = &dev->dev; /* for pci drivers */
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; /* this will be the only time xxxfb_fix will be
* used, so mark it as __initdata
*/
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.scan_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 been done !!! */
fb_alloc_cmap(info->cmap, cmap_len, 0);
/*
* 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)
return -EINVAL;
printk(KERN_INFO "fb%d: %s frame buffer device\n", info->node,
info->fix.id);
pci_set_drvdata(dev, info); /* or dev_set_drvdata(device, info) */
return 0;
}
/*
* Cleanup
*/
/* static void __exit xxxfb_remove(struct device *device) */
static void __exit xxxfb_remove(struct pci_dev *dev)
{
struct fb_info *info = pci_get_drv_data(dev);
/* or dev_get_drv_data(device); */
if (info) {
unregister_framebuffer(info);
fb_dealloc_cmap(&info.cmap);
/* ... */
framebuffer_release(info);
}
return 0;
}
#if CONFIG_PCI
/* For PCI drivers */
static struct pci_driver xxxfb_driver = {
.name = "xxxfb",
.id_table = xxxfb_devices,
.probe = xxxfb_probe,
.remove = __devexit_p(xxxfb_remove),
.suspend = xxxfb_suspend, /* optional */
.resume = xxxfb_resume, /* optional */
};
static int __init xxxfb_init(void)
{
/*
* For kernel boot options (in 'video=xxxfb:<options>' format)
*/
@ -564,68 +852,64 @@ int __init xxxfb_init(void)
xxxfb_setup(option);
#endif
/*
* 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;
/*
* 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
*/
info.flags = FBINFO_DEFAULT;
info.par = current_par;
/*
* 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 been done !!! */
fb_alloc_cmap(&info.cmap, cmap_len, 0);
/*
* 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;
if (register_framebuffer(&info) < 0)
return -EINVAL;
printk(KERN_INFO "fb%d: %s frame buffer device\n", info.node,
info.fix.id);
return 0;
return pci_register_driver(&xxxfb_driver);
}
/*
* Cleanup
*/
static void __exit xxxfb_cleanup(void)
static void __exit xxxfb_exit(void)
{
/*
* If your driver supports multiple boards, you should unregister and
* clean up all instances.
*/
unregister_framebuffer(info);
fb_dealloc_cmap(&info.cmap);
/* ... */
pci_unregister_driver(&xxxfb_driver);
}
#else
#include <linux/platform_device.h>
/* for platform devices */
static struct device_driver xxxfb_driver = {
.name = "xxxfb",
.bus = &platform_bus_type,
.probe = xxxfb_probe,
.remove = xxxfb_remove,
.suspend = xxxfb_suspend, /* optional */
.resume = xxxfb_resume, /* optional */
};
static struct platform_device xxxfb_device = {
.name = "xxxfb",
};
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 = driver_register(&xxxfb_driver);
if (!ret) {
ret = platform_device_register(&xxxfb_device);
if (ret)
driver_unregister(&xxxfb_driver);
}
return ret;
}
static void __exit xxxfb_exit(void)
{
platform_device_unregister(&xxxfb_device);
driver_unregister(&xxxfb_driver);
}
#endif
MODULE_LICENSE("GPL");
module_init(xxxfb_init);
module_exit(xxxfb_exit);
/*
* Setup