framebuffer驱动分析（三）

4.fb.h

   framebuffer struct define

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！

#ifndef _LINUX_FB_H

#define _LINUX_FB_H

#include

#include

/* 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

　

Framebuffer驱动程序模型

下图会向你展示目前的framebuffer设备驱动的结构，最常用的是非标准驱动。很明显他所处的层次最高，程序编写是最容易的。

理解了这个图的，你已经很轻松的去完成一个fb驱动，比如给sa1100,s2410,s2440系列的ARM的LCD控制器写驱动。

下面分析颜色映射表

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);

在struct fb_info结构中有变量：

struct fb_cmap cmap;                 /* Current cmap */

在fpgen基础操作下提供：

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

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

在文件/* drivers/video/fbcmap.c */中提供更多的cmap应用

extern int fb_alloc_cmap(struct fb_cmap *cmap, int len, int transp);

extern void fb_copy_cmap(struct fb_cmap *from, struct fb_cmap *to, int fsfromto);

extern int fb_get_cmap(struct fb_cmap *cmap, int kspc,

int (*getcolreg)(u_int, u_int *, u_int *, u_int *,u_int *, struct fb_info *),

                               struct fb_info *fb_info);

extern int fb_set_cmap(struct fb_cmap *cmap, int kspc,

                              int (*setcolreg)(u_int, u_int, u_int, u_int, u_int,struct fb_info *),

                              struct fb_info *fb_info);

extern struct fb_cmap *fb_default_cmap(int len);

extern void fb_invert_cmaps(void);

2． 通过文件解析

在anakinfb.c文件中，cmap如图

在stifb.c