LCD(二) linux驱动分析

数据结构

//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_IO    struct delayed_work deferred_work;    struct fb_deferred_io *fbdefio;#endif    struct 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" */    unsigned long 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。

驱动框架

驱动例子

#include <linux/delay.h>#include <linux/fb.h>#include <linux/init.h>#include <linux/dma-mapping.h>#include <linux/interrupt.h>#include <linux/workqueue.h>#include <linux/wait.h>#include <linux/platform_device.h>#include <linux/clk.h>#include <asm/io.h>#include <asm/uaccess.h>#include <asm/div64.h>#include <asm/mach/map.h>#include <asm/arch/regs-lcd.h>#include <asm/arch/regs-gpio.h>#include <asm/arch/fb.h>static int s3c_lcdfb_setcolreg(unsigned int regno, unsigned int red,                 unsigned int green, unsigned int blue,                 unsigned int transp, struct fb_info *info);struct lcd_regs {    unsigned long   lcdcon1;    unsigned long   lcdcon2;    unsigned long   lcdcon3;    unsigned long   lcdcon4;    unsigned long   lcdcon5;    unsigned long   lcdsaddr1;    unsigned long   lcdsaddr2;    unsigned long   lcdsaddr3;    unsigned long   redlut;    unsigned long   greenlut;    unsigned long   bluelut;    unsigned long   reserved[9];    unsigned long   dithmode;    unsigned long   tpal;    unsigned long   lcdintpnd;    unsigned long   lcdsrcpnd;    unsigned long   lcdintmsk;    unsigned long   lpcsel;};static struct fb_ops s3c_lcdfb_ops = {    .owner      = THIS_MODULE,    .fb_setcolreg   = s3c_lcdfb_setcolreg,    .fb_fillrect    = cfb_fillrect,    .fb_copyarea    = cfb_copyarea,    .fb_imageblit   = cfb_imageblit,};static struct fb_info *s3c_lcd;static volatile unsigned long *gpbcon;static volatile unsigned long *gpbdat;static volatile unsigned long *gpccon;static volatile unsigned long *gpdcon;static volatile unsigned long *gpgcon;static volatile struct lcd_regs* lcd_regs;static u32 pseudo_palette[16];/* from pxafb.c */static inline unsigned int chan_to_field(unsigned int chan, struct fb_bitfield *bf){    chan &= 0xffff;    chan >>= 16 - bf->length;    return chan << bf->offset;}static int s3c_lcdfb_setcolreg(unsigned int regno, unsigned int red,                 unsigned int green, unsigned int blue,                 unsigned int transp, struct fb_info *info){    unsigned int val;    if (regno > 16)        return 1;    /* 用red,green,blue三原色构造出val */    val  = chan_to_field(red,   &info->var.red);    val |= chan_to_field(green, &info->var.green);    val |= chan_to_field(blue,  &info->var.blue);    //((u32 *)(info->pseudo_palette))[regno] = val;    pseudo_palette[regno] = val;    return 0;}static int lcd_init(void){    /* 1. 分配一个fb_info */    s3c_lcd = framebuffer_alloc(0, NULL);    /* 2. 设置 */    /* 2.1 设置固定的参数 */    strcpy(s3c_lcd->fix.id, "mylcd");    s3c_lcd->fix.smem_len = 240*320*16/8;    s3c_lcd->fix.type     = FB_TYPE_PACKED_PIXELS;    s3c_lcd->fix.visual   = FB_VISUAL_TRUECOLOR; /* TFT */    s3c_lcd->fix.line_length = 240*2;    /* 2.2 设置可变的参数 */    s3c_lcd->var.xres           = 240;    s3c_lcd->var.yres           = 320;    s3c_lcd->var.xres_virtual   = 240;    s3c_lcd->var.yres_virtual   = 320;    s3c_lcd->var.bits_per_pixel = 16;    /* RGB:565 */    s3c_lcd->var.red.offset     = 11;    s3c_lcd->var.red.length     = 5;    s3c_lcd->var.green.offset   = 5;    s3c_lcd->var.green.length   = 6;    s3c_lcd->var.blue.offset    = 0;    s3c_lcd->var.blue.length    = 5;    s3c_lcd->var.activate       = FB_ACTIVATE_NOW;    /* 2.3 设置操作函数 */    s3c_lcd->fbops              = &s3c_lcdfb_ops;    /* 2.4 其他的设置 */    s3c_lcd->pseudo_palette = pseudo_palette;    //s3c_lcd->screen_base  = ;  /* 显存的虚拟地址 */     s3c_lcd->screen_size   = 240*324*16/8;    /* 3. 硬件相关的操作 */    /* 3.1 配置GPIO用于LCD */    gpbcon = ioremap(0x56000010, 8);    gpbdat = gpbcon+1;    gpccon = ioremap(0x56000020, 4);    gpdcon = ioremap(0x56000030, 4);    gpgcon = ioremap(0x56000060, 4);    *gpccon  = 0xaaaaaaaa;   /* GPIO管脚用于VD[7:0],LCDVF[2:0],VM,VFRAME,VLINE,VCLK,LEND */    *gpdcon  = 0xaaaaaaaa;   /* GPIO管脚用于VD[23:8] */    *gpbcon &= ~(3);  /* GPB0设置为输出引脚 */    *gpbcon |= 1;    *gpbdat &= ~1;     /* 输出低电平 */    *gpgcon |= (3<<8); /* GPG4用作LCD_PWREN */    /* 3.2 根据LCD手册设置LCD控制器, 比如VCLK的频率等 */    lcd_regs = ioremap(0x4D000000, sizeof(struct lcd_regs));    /* bit[17:8]: VCLK = HCLK / [(CLKVAL+1) x 2], LCD手册P14     *            10MHz(100ns) = 100MHz / [(CLKVAL+1) x 2]     *            CLKVAL = 4     * bit[6:5]: 0b11, TFT LCD     * bit[4:1]: 0b1100, 16 bpp for TFT     * bit[0]  : 0 = Disable the video output and the LCD control signal.     */    lcd_regs->lcdcon1  = (4<<8) | (3<<5) | (0x0c<<1);#if 1    /* 垂直方向的时间参数     * bit[31:24]: VBPD, VSYNC之后再过多长时间才能发出第1行数据     *             LCD手册 T0-T2-T1=4     *             VBPD=3     * bit[23:14]: 多少行, 320, 所以LINEVAL=320-1=319     * bit[13:6] : VFPD, 发出最后一行数据之后，再过多长时间才发出VSYNC     *             LCD手册T2-T5=322-320=2, 所以VFPD=2-1=1     * bit[5:0]  : VSPW, VSYNC信号的脉冲宽度, LCD手册T1=1, 所以VSPW=1-1=0     */    lcd_regs->lcdcon2  = (3<<24) | (319<<14) | (1<<6) | (0<<0);    /* 水平方向的时间参数     * bit[25:19]: HBPD, VSYNC之后再过多长时间才能发出第1行数据     *             LCD手册 T6-T7-T8=17     *             HBPD=16     * bit[18:8]: 多少列, 240, 所以HOZVAL=240-1=239     * bit[7:0] : HFPD, 发出最后一行里最后一个象素数据之后，再过多长时间才发出HSYNC     *             LCD手册T8-T11=251-240=11, 所以HFPD=11-1=10     */    lcd_regs->lcdcon3 = (16<<19) | (239<<8) | (10<<0);    /* 水平方向的同步信号     * bit[7:0] : HSPW, HSYNC信号的脉冲宽度, LCD手册T7=5, 所以HSPW=5-1=4     */     lcd_regs->lcdcon4 = 4;#elselcd_regs->lcdcon2 = S3C2410_LCDCON2_VBPD(5) | \        S3C2410_LCDCON2_LINEVAL(319) | \        S3C2410_LCDCON2_VFPD(3) | \        S3C2410_LCDCON2_VSPW(1);lcd_regs->lcdcon3 = S3C2410_LCDCON3_HBPD(10) | \        S3C2410_LCDCON3_HOZVAL(239) | \        S3C2410_LCDCON3_HFPD(1);lcd_regs->lcdcon4 = S3C2410_LCDCON4_MVAL(13) | \        S3C2410_LCDCON4_HSPW(0);#endif    /* 信号的极性      * bit[11]: 1=565 format     * bit[10]: 0 = The video data is fetched at VCLK falling edge     * bit[9] : 1 = HSYNC信号要反转,即低电平有效      * bit[8] : 1 = VSYNC信号要反转,即低电平有效      * bit[6] : 0 = VDEN不用反转     * bit[3] : 0 = PWREN输出0     * bit[1] : 0 = BSWP     * bit[0] : 1 = HWSWP 2440手册P413     */    lcd_regs->lcdcon5 = (1<<11) | (0<<10) | (1<<9) | (1<<8) | (1<<0);    /* 3.3 分配显存(framebuffer), 并把地址告诉LCD控制器 */    s3c_lcd->screen_base = dma_alloc_writecombine(NULL, s3c_lcd->fix.smem_len, &s3c_lcd->fix.smem_start, GFP_KERNEL);    lcd_regs->lcdsaddr1  = (s3c_lcd->fix.smem_start >> 1) & ~(3<<30);    lcd_regs->lcdsaddr2  = ((s3c_lcd->fix.smem_start + s3c_lcd->fix.smem_len) >> 1) & 0x1fffff;    lcd_regs->lcdsaddr3  = (240*16/16);  /* 一行的长度(单位: 2字节) */       //s3c_lcd->fix.smem_start = xxx;  /* 显存的物理地址 */    /* 启动LCD */    lcd_regs->lcdcon1 |= (1<<0); /* 使能LCD控制器 */    lcd_regs->lcdcon5 |= (1<<3); /* 使能LCD本身 */    *gpbdat |= 1;     /* 输出高电平, 使能背光 */         /* 4. 注册 */    register_framebuffer(s3c_lcd);    return 0;}static void lcd_exit(void){    unregister_framebuffer(s3c_lcd);    lcd_regs->lcdcon1 &= ~(1<<0); /* 关闭LCD本身 */    *gpbdat &= ~1;     /* 关闭背光 */    dma_free_writecombine(NULL, s3c_lcd->fix.smem_len, s3c_lcd->screen_base, s3c_lcd->fix.smem_start);    iounmap(lcd_regs);    iounmap(gpbcon);    iounmap(gpccon);    iounmap(gpdcon);    iounmap(gpgcon);    framebuffer_release(s3c_lcd);}module_init(lcd_init);module_exit(lcd_exit);MODULE_LICENSE("GPL");