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authorAntonino A. Daplas <adaplas@gmail.com>2006-01-09 20:53:34 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-10 08:01:49 -0800
commitd911233fe6632981086942a6b66e7ae5dabaaadc (patch)
tree6608709b71f04173beb0263c76a66bc1b7b2d4a9 /drivers/video/skeletonfb.c
parentc549dc6422e4b720fed6702d70fddd8cee0f5c9a (diff)
downloadlinux-d911233fe6632981086942a6b66e7ae5dabaaadc.tar.gz
[PATCH] skeletonfb: Documentation update
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>
Diffstat (limited to 'drivers/video/skeletonfb.c')
-rw-r--r--drivers/video/skeletonfb.c482
1 files changed, 383 insertions, 99 deletions
diff --git a/drivers/video/skeletonfb.c b/drivers/video/skeletonfb.c
index a01e7ecc15e..9b707771d75 100644
--- a/drivers/video/skeletonfb.c
+++ b/drivers/video/skeletonfb.c
@@ -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;
}
@@ -258,70 +297,110 @@ 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;
- }
+ 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
- /* Truecolor has hardware independent palette */
- if (info->fix.visual == FB_VISUAL_TRUECOLOR) {
- 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);
-
- 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;
+ /*
+ * 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;
}
@@ -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)
{
@@ -549,20 +656,25 @@ 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;
/*
- * For kernel boot options (in 'video=xxxfb:<options>' format)
+ * Dynamically allocate info and par
*/
-#ifndef MODULE
- char *option = NULL;
+ info = framebuffer_alloc(sizeof(struct xxx_par), device);
- if (fb_get_options("xxxfb", &option))
- return -ENODEV;
- xxxfb_setup(option);
-#endif
+ if (!info) {
+ /* goto error path */
+ }
+
+ par = info->par;
/*
* Here we set the screen_base to the virtual memory address
@@ -570,18 +682,87 @@ int __init xxxfb_init(void)
* 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;
-
+ 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.flags = FBINFO_DEFAULT;
- info.par = current_par;
+ 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
@@ -590,42 +771,145 @@ int __init xxxfb_init(void)
if (!mode_option)
mode_option = "640x480@60";
- retval = fb_find_mode(&info.var, &info, mode_option, NULL, 0, NULL, 8);
+ 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);
+ 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)
+ 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);
+ 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;
+}
-static void __exit xxxfb_cleanup(void)
+#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)
{
- /*
- * If your driver supports multiple boards, you should unregister and
- * clean up all instances.
- */
+ /*
+ * For kernel boot options (in 'video=xxxfb:<options>' format)
+ */
+#ifndef MODULE
+ char *option = NULL;
- unregister_framebuffer(info);
- fb_dealloc_cmap(&info.cmap);
- /* ... */
+ 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
+#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