frambuffer.txt

基于LINUX操作系统下的各种详细配置（如FTP

索引颜色显示



True color (FB_VISUAL_TRUECOLOR)
--------------------------------

真彩显示，分成红绿兰三基色



Direct color (FB_VISUAL_DIRECTCOLOR)
------------------------------------

每个象素颜色也是有红绿蓝组成，不过每个颜色值是个索引，需要查表。



Grayscale displays
------------------

灰度显示，红绿蓝的值都一样


准备开始写我们自己的驱动之前，请详细阅读如下文件：

\Documentation\fb目录  vesafb.txt，matroxfb.txt，sa1100fb.txt
\drivers\video目录          fbmem.c，fbgen.c，fbmon.c，fbcmap.c
                                      skeletonfb.c
                                      vesafb.c，sa1100fb.c，sa1100fb.h
include\linux目录            fb.h

最值得关注的是skeletonfb.c，该文件给出了一个fb device 驱动的框架

准备好了，就开始写自己的fram buffer device driver：）


还是要补充点，下面是/linux/fb.h的部分注释，加粗的是常用的，红色是关键的，一般不可少。旁边没有汉字，要么很简单没必要加注，要么就用不到！

注释：[e-mail]



#ifndef _LINUX_FB_H

#define _LINUX_FB_H



#include <linux/tty.h>

#include <asm/types.h>



/* Definitions of frame buffers                     */



#define FB_MAJOR        29  /*主设备号*/

#define FB_MAX          32  /* sufficient for now */



/* ioctls

   0x46 is 'F'                              */

#define FBIOGET_VSCREENINFO 0x4600

#define FBIOPUT_VSCREENINFO 0x4601

#define FBIOGET_FSCREENINFO 0x4602

#define FBIOGETCMAP     0x4604

#define FBIOPUTCMAP     0x4605

#define FBIOPAN_DISPLAY     0x4606

/* 0x4607-0x460B are defined below */

/* #define FBIOGET_MONITORSPEC  0x460C */

/* #define FBIOPUT_MONITORSPEC  0x460D */

/* #define FBIOSWITCH_MONIBIT   0x460E */

#define FBIOGET_CON2FBMAP   0x460F

#define FBIOPUT_CON2FBMAP   0x4610

#define FBIOBLANK       0x4611      /* arg: 0 or vesa level + 1 */

#define FBIOGET_VBLANK      _IOR('F', 0x12, struct fb_vblank)

#define FBIO_ALLOC              0x4613

#define FBIO_FREE               0x4614

#define FBIOGET_GLYPH           0x4615

#define FBIOGET_HWCINFO         0x4616

#define FBIOPUT_MODEINFO        0x4617

#define FBIOGET_DISPINFO        0x4618





#define FB_TYPE_PACKED_PIXELS       0   /* Packed Pixels    */

#define FB_TYPE_PLANES          1   /* Non interleaved planes */

#define FB_TYPE_INTERLEAVED_PLANES  2   /* Interleaved planes   */

#define FB_TYPE_TEXT            3   /* Text/attributes  */

#define FB_TYPE_VGA_PLANES      4   /* EGA/VGA planes   */



#define FB_AUX_TEXT_MDA     0   /* Monochrome text */

#define FB_AUX_TEXT_CGA     1   /* CGA/EGA/VGA Color text */

#define FB_AUX_TEXT_S3_MMIO 2   /* S3 MMIO fasttext */

#define FB_AUX_TEXT_MGA_STEP16  3   /* MGA Millenium I: text, attr, 14 reserved bytes */

#define FB_AUX_TEXT_MGA_STEP8   4   /* other MGAs:      text, attr,  6 reserved bytes */



#define FB_AUX_VGA_PLANES_VGA4      0   /* 16 color planes (EGA/VGA) */

#define FB_AUX_VGA_PLANES_CFB4      1   /* CFB4 in planes (VGA) */

#define FB_AUX_VGA_PLANES_CFB8      2   /* CFB8 in planes (VGA) */



#define FB_VISUAL_MONO01        0   /* Monochr. 1=Black 0=White */

#define FB_VISUAL_MONO10        1   /* Monochr. 1=White 0=Black */

#define FB_VISUAL_TRUECOLOR     2   /* True color   */

#define FB_VISUAL_PSEUDOCOLOR       3   /* Pseudo color (like atari) */

#define FB_VISUAL_DIRECTCOLOR       4   /* Direct color */

#define FB_VISUAL_STATIC_PSEUDOCOLOR    5   /* Pseudo color readonly */



#define FB_ACCEL_NONE       0   /* no hardware accelerator  */

#define FB_ACCEL_ATARIBLITT 1   /* Atari Blitter        */

#define FB_ACCEL_AMIGABLITT 2   /* Amiga Blitter                */

#define FB_ACCEL_S3_TRIO64  3   /* Cybervision64 (S3 Trio64)    */

#define FB_ACCEL_NCR_77C32BLT   4   /* RetinaZ3 (NCR 77C32BLT)      */

#define FB_ACCEL_S3_VIRGE   5   /* Cybervision64/3D (S3 ViRGE)  */

#define FB_ACCEL_ATI_MACH64GX   6   /* ATI Mach 64GX family     */

#define FB_ACCEL_DEC_TGA    7   /* DEC 21030 TGA        */

#define FB_ACCEL_ATI_MACH64CT   8   /* ATI Mach 64CT family     */

#define FB_ACCEL_ATI_MACH64VT   9   /* ATI Mach 64CT family VT class */

#define FB_ACCEL_ATI_MACH64GT   10  /* ATI Mach 64CT family GT class */

#define FB_ACCEL_SUN_CREATOR    11  /* Sun Creator/Creator3D    */

#define FB_ACCEL_SUN_CGSIX  12  /* Sun cg6          */

#define FB_ACCEL_SUN_LEO    13  /* Sun leo/zx           */

#define FB_ACCEL_IMS_TWINTURBO  14  /* IMS Twin Turbo       */

#define FB_ACCEL_3DLABS_PERMEDIA2 15    /* 3Dlabs Permedia 2        */

#define FB_ACCEL_MATROX_MGA2064W 16 /* Matrox MGA2064W (Millenium)  */

#define FB_ACCEL_MATROX_MGA1064SG 17    /* Matrox MGA1064SG (Mystique)  */

#define FB_ACCEL_MATROX_MGA2164W 18 /* Matrox MGA2164W (Millenium II) */

#define FB_ACCEL_MATROX_MGA2164W_AGP 19 /* Matrox MGA2164W (Millenium II) */

#define FB_ACCEL_MATROX_MGAG100 20  /* Matrox G100 (Productiva G100) */

#define FB_ACCEL_MATROX_MGAG200 21  /* Matrox G200 (Myst, Mill, ...) */

#define FB_ACCEL_SUN_CG14   22  /* Sun cgfourteen       */

#define FB_ACCEL_SUN_BWTWO  23  /* Sun bwtwo            */

#define FB_ACCEL_SUN_CGTHREE    24  /* Sun cgthree          */

#define FB_ACCEL_SUN_TCX    25  /* Sun tcx          */

#define FB_ACCEL_MATROX_MGAG400 26  /* Matrox G400          */

#define FB_ACCEL_NV3        27  /* nVidia RIVA 128              */

#define FB_ACCEL_NV4        28  /* nVidia RIVA TNT      */

#define FB_ACCEL_NV5        29  /* nVidia RIVA TNT2     */

#define FB_ACCEL_CT_6555x   30  /* C&T 6555x            */

#define FB_ACCEL_3DFX_BANSHEE   31  /* 3Dfx Banshee         */

#define FB_ACCEL_ATI_RAGE128    32  /* ATI Rage128 family       */

#define FB_ACCEL_IGS_CYBER2000  33  /* CyberPro 2000        */

#define FB_ACCEL_IGS_CYBER2010  34  /* CyberPro 2010        */

#define FB_ACCEL_IGS_CYBER5000  35  /* CyberPro 5000        */

#define FB_ACCEL_SIS_GLAMOUR    36  /* SiS 300/630/540              */

#define FB_ACCEL_3DLABS_PERMEDIA3 37    /* 3Dlabs Permedia 3        */

/*上面的宏定义不用关心*/



/*不可修改的屏幕信息，用户空间可见*/

struct fb_fix_screeninfo {

    char id[16];         /* identification string eg "TT Builtin" */

    unsigned long smem_start;   /* Start of frame buffer mem 显存的起始地址*/

                  /* (physical address) */

    __u32 smem_len;          /* Length of frame buffer mem 显存的大小 */

    __u32 type;          /* see FB_TYPE_*     */

    __u32 type_aux;          /* Interleave for interleaved Planes */

    __u32 visual;        /* see FB_VISUAL_*       */ 

    __u16 xpanstep;          /* zero if no hardware panning  */

    __u16 ypanstep;          /* zero if no hardware panning  */

    __u16 ywrapstep;     /* zero if no hardware ywrap    */

    __u32 line_length;       /* length of a line in bytes  每行的字节数  */

    unsigned long mmio_start;   /* Start of Memory Mapped I/O   */

                  /* (physical address) */

    __u32 mmio_len;          /* Length of Memory Mapped I/O  */

    __u32 accel;           /* Type of acceleration available */

    __u16 reserved[3];       /* Reserved for future compatibility */

};



/* Interpretation of offset for color fields: All offsets are from the right,

* inside a "pixel" value, which is exactly 'bits_per_pixel' wide (means: you

* can use the offset as right argument to <<). A pixel afterwards is a bit

* stream and is written to video memory as that unmodified. This implies

* big-endian byte order if bits_per_pixel is greater than 8.

*/

/*像素所占字节内，各个颜色的位分配比如RGB=888,565,555等等，*/

struct fb_bitfield {

    __u32 offset;        /* beginning of bitfield */

    __u32 length;        /* length of bitfield       */

    __u32 msb_right;     /* != 0 : Most significant bit is */ 

                  /* right */ 

};



/*下面的宏也不常用*/

#define FB_NONSTD_HAM       1   /* Hold-And-Modify (HAM)        */



#define FB_ACTIVATE_NOW     0   /* set values immediately (or vbl)*/

#define FB_ACTIVATE_NXTOPEN 1   /* activate on next open    */

#define FB_ACTIVATE_TEST    2   /* don't set, round up impossible */

#define FB_ACTIVATE_MASK       15

                    /* values           */

#define FB_ACTIVATE_VBL        16   /* activate values on next vbl  */

#define FB_CHANGE_CMAP_VBL     32   /* change colormap on vbl   */

#define FB_ACTIVATE_ALL        64   /* change all VCs on this fb    */



#define FB_ACCELF_TEXT      1   /* text mode acceleration */



#define FB_SYNC_HOR_HIGH_ACT    1   /* horizontal sync high active  */

#define FB_SYNC_VERT_HIGH_ACT   2   /* vertical sync high active    */

#define FB_SYNC_EXT     4   /* external sync        */

#define FB_SYNC_COMP_HIGH_ACT   8   /* composite sync high active   */

#define FB_SYNC_BROADCAST   16  /* broadcast video timings 


在framebuffer驱动程序设计中，cmap这个东东太晕了。现在我要把他赤裸裸的剖析给大家：）

1． struct fb_cmap





/*颜色映射表*/

struct fb_cmap {

       __u32 start;                  /* First entry   */

       __u32 len;                    /* Number of entries */

       __u16 *red;                  /* 红色   */

       __u16 *green;               /*绿色*/

       __u16 *blue;                 /*蓝色*/

       __u16 *transp;                     /* 透明度,允许 NULL */

};

该结构在fb.h文件中定义，在struct fb_ops结构中有两个成员函数与其相关：

    /*获取颜色表*/

    int (*fb_get_cmap)(struct fb_cmap *cmap, int kspc, int con, struct fb_info *info);

    /*设定颜色表*/

    int (*fb_set_cmap)(struct fb_cmap *cmap, int kspc, int con, struct fb_info *info);