LCD(二) linux驱动分析

//struct fb_infostruct fb_info { int node; int flags; struct mutex lock; /* Lock for open/release/ioctl funcs */struct mutex mm_lock; /* Lock for fb_mmap and smem_* fields */struct fb_var_screeninfo var;/* 可变参数 */struct fb_fix_screeninfo fix; /* 固定参数 */struct fb_monspecs monspecs; /* 显示器标准特性 */struct work_struct queue; /* Framebuffer event queue */struct fb_pixmap pixmap; /* 图像硬件mapper */struct fb_pixmap sprite; /* 光标硬件 mapper */struct fb_cmap cmap; /* 颜色表 */struct list_head modelist; /* mode list */struct fb_videomode *mode; /* video模式 */#ifdef CONFIG_FB_BACKLIGHT //背光驱动/* assigned backlight device *//* set before framebuffer registration, remove after unregister */struct backlight_device *bl_dev; /* Backlight level curve */struct mutex bl_curve_mutex; u8 bl_curve[FB_BACKLIGHT_LEVELS];#endif#ifdef CONFIG_FB_DEFERRED_IOstruct delayed_work deferred_work; struct fb_deferred_io *fbdefio;#endifstruct fb_ops *fbops; //对帧缓冲的操作struct device *device; /* This is the parent */struct device *dev; /* This is this fb device */int class_flag; /* private sysfs flags */char __iomem *screen_base; /* 显存虚拟基地址 */ unsigned long screen_size; /* 显存大小 */void *pseudo_palette; /* 伪16色颜色表*/#define FBINFO_STATE_RUNNING 0#define FBINFO_STATE_SUSPENDED 1 u32 state;/* Hardware state i.e suspend */void *fbcon_par; /* fbcon use-only private area *//* From here on everything is device dependent */void *par; //.....};struct fb_var_screeninfo { __u32 xres; //可见分辨率 __u32 yres; __u32 xres_virtual; __u32 yres_virtual; __u32 xoffset; __u32 yoffset; __u32 bits_per_pixel;//每个像素位数 __u32 grayscale; struct fb_bitfield red; //颜色位域struct fb_bitfield green; struct fb_bitfield blue; struct fb_bitfield transp; //透明度__u32 nonstd; __u32 activate; __u32 height;/* height of picture in mm */ __u32 width; /* width of picture in mm */ __u32 accel_flags; /* (OBSOLETE) see fb_info.flags *///时序/* Timing: All values in pixclocks, except pixclock (of course) */ __u32 pixclock;/* pixel clock in ps (皮秒) */ __u32 left_margin;/* time from sync to picture */ __u32 right_margin; /* time from picture to sync */ __u32 upper_margin; /* time from sync to picture */ __u32 lower_margin; __u32 hsync_len; /* length of horizontal sync */ __u32 vsync_len; /* length of vertical sync */ __u32 sync; /* see FB_SYNC_* */ __u32 vmode; /* see FB_VMODE_* */ __u32 rotate; /* angle we rotate counter clockwise */ __u32 reserved[5];/* Reserved for future compatibility */};struct fb_fix_screeninfo { char id[16];/* identification string eg "TT Builtin" */ unsignedlong smem_start; /* Start of frame buffer mem *//* (physical address) */ __u32 smem_len;/* Length of frame buffer mem */ __u32 type;/* see FB_TYPE_* */ __u32 type_aux;/* Interleave for interleaved Planes */ __u32 visual; /* see FB_VISUAL_* *///色彩模式，真彩色，伪彩色 __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 */ unsigned long mmio_start; /* Start of Memory Mapped I/O *//* (physical address) */ __u32 mmio_len;/* Length of Memory Mapped I/O */ __u32 accel;/* Indicate to driver which *//* specific chip/card we have */ __u16 reserved[3];/* Reserved for future compatibility */};//颜色位域struct fb_bitfield { __u32 offset; /* beginning of bitfield */ __u32 length; /* length of bitfield */ __u32 msb_right; /* != 0 : Most significant bit is *//* right */ };//像素深度：BPP// 像素深度是指存储每个像素所用的位数，它也是用来度量图像的分辨率。//像素深度决定彩色图像的每个像素可能有的颜色数，或者确定灰度图像//的每个像素可能有的灰度级数，例如，一幅彩色图像的每个像素用R，//就说像素的深度为24，每个像素可以是16 777 216（2的24次方）种颜//色中的一种。在这个意义上，往往把像素深度说成是图像深度。//表示一个像素的位数越多，它能表达的颜色数目就越多，而它的深度就越深。//调色板原理<详见调色板原理>：// 在计算机图像技术中,一个像素的颜色是由它的R,G,B分量表示的,//每个分量又经过量化,一个像素总的量化级数就是这个显示系统的颜色//深度。量化级数越高,可以表示的颜色也就越多,最终的图像也就越逼真。//当量化级数达到16位以上时,被称为真彩色。但是,量化级数越高,就需//要越高的数据宽度,给处理器带来的负担也就越重;量化级数在8位以下时,//所能表达的颜色又太少,不能够满足用户特定的需求。//　　为了解决这个问题,可以采取调色板技术。所谓调色板,就是在低颜色//深度的模式下,在有限的像素值与RGB颜色之间建立对应关系的一个线性表。//比如说,从所有的16位彩色中抽取一定数量的颜色,编制索引。当需要使用//某种彩色时,不需要对这种颜色的RGB分量进行描述,只需要引用它的索引号,//就可以使用户选取自己需要的颜色。索引号的编码长度远远小于RGB分量的//编码长度,因此在彩色显示的同时,也大大减轻了系统的负担。//　　以256色调色板为例,调色板中存储256种颜色的RGB值,每种颜色的RGB值//是16位。用这256种颜色编制索引时,从00H~FFH只需要8位数据宽度,而每个//索引所对应的颜色却是16位宽度的颜色信息。在一些对色彩种类要求不高的场合,//如仪表终端、信息终端等,调色板技术便巧妙地解决了数据宽度与颜色深度之间//的矛盾。