jz2440_lcd

VDEN      使能信号

HSYNC    水平方向的同步信号

VSYNC    垂直方向的同步信号

LED-/LED+   背光信号

VCLK       时钟信号

VD0~VD23    数字信号

GPB0输出为1

驱动程序中：
lcd_init:
---------------------------------------------------------
static struct fb_info *s3c_lcd;    //定义一个结构体
/* 1. 分配一个fb_info */
    s3c_lcd = framebuffer_alloc(, NULL);    //不需要额外的空间

--------------------3.4.2内核中的函数-----------------------------------------
struct fb_info {
struct fb_var_screeninfo var;    /* Current var可变参数 */
struct fb_fix_screeninfo fix;      /* Current fix 固定参数*/
struct fb_ops *fbops;                /*操作参数*/
void *pseudo_palette;        /* Fake palette of 16 colors 其他设置*/
unsigned long screen_size;    /* Amount of ioremapped VRAM or 0显存的大小 */
}
-----------------------------------------------------------------------------
/* 2. 设置 */
/* 2.1 设置固定的参数 */
strcpy(s3c_lcd->fix.id, "mylcd");                //名字
    s3c_lcd->fix.smem_len = **/;        //显存的长度
    s3c_lcd->fix.type     = FB_TYPE_PACKED_PIXELS;    //看不懂默认0
    s3c_lcd->fix.visual   = FB_VISUAL_TRUECOLOR; /* TFT (真彩色)*/
    s3c_lcd->fix.line_length = *;    //长度*2个字节

--------------------3.4.2内核中的函数-----------------------------------------

   struct fb_fix_screeninfo {
    char id[];            /* 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_*        */
    __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 capabilities;        /* see FB_CAP_*            */
    __u16 reserved[];        /* Reserved for future compatibility */
};
 ---------------------------------------------------------------------
/* 2.2 设置可变的参数 */
s3c_lcd->var.xres           = ;    //x方向的分辨率
    s3c_lcd->var.yres           = ;    //y方向的分辨率
    s3c_lcd->var.xres_virtual   = ;    //x方向的虚拟分辨率
    s3c_lcd->var.yres_virtual   = ;    //y方向的虚拟分辨率
    s3c_lcd->var.bits_per_pixel = ;        //每个像素用多少位
    /* RGB:565 */
    s3c_lcd->var.red.offset     = ;    //从那位开始
    s3c_lcd->var.red.length     = ;    //长度
    s3c_lcd->var.green.offset   = ;
    s3c_lcd->var.green.length   = ;
    s3c_lcd->var.blue.offset    = ;
    s3c_lcd->var.blue.length    = ;
    s3c_lcd->var.activate       = FB_ACTIVATE_NOW;

--------------------3.4.2内核中的函数-----------------------------------------

struct fb_var_screeninfo {
    __u32 xres;            /* visible resolution        */
    __u32 yres;
    __u32 xres_virtual;        /* virtual resolution        */
    __u32 yres_virtual;
    __u32 xoffset;            /* offset from virtual to visible */
    __u32 yoffset;            /* resolution            */
    __u32 bits_per_pixel;        /* guess what            */
    __u32 grayscale;        /* 0 = color, 1 = grayscale,    */
                    /* >1 = FOURCC            */
    struct fb_bitfield red;        /* bitfield in fb mem if true color, */
    struct fb_bitfield green;    /* else only length is significant */
    struct fb_bitfield blue;
    struct fb_bitfield transp;    /* transparency            */
    __u32 nonstd;            /* != 0 Non standard pixel format */
    __u32 activate;            /* see FB_ACTIVATE_*        */
    __u32 height;            /* height of picture in mm    */
    __u32 width;            /* width of picture in mm     */
    __u32 accel_flags;        /* (OBSOLETE) see fb_info.flags */
    /* Timing: All values in pixclocks, except pixclock (of course) */
    __u32 pixclock;            /* pixel clock in ps (pico seconds) */
    __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 colorspace;        /* colorspace for FOURCC-based modes */
    __u32 reserved[];        /* Reserved for future compatibility */
};
---------------------------------------------------------------------
/* 2.3 设置操作函数 */
s3c_lcd->fbops              = &s3c_lcdfb_ops;

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,
};

/* 2.4 其他的设置 */
   static u32 pseudo_palette[];            //定义
    s3c_lcd->pseudo_palette = pseudo_palette;        //调色板

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 > )
        return ;
    /* 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 ;
}
/* from pxafb.c */
static inline unsigned int chan_to_field(unsigned int chan, struct fb_bitfield *bf)
{
    chan &= 0xffff;
    chan >>=  - bf->length;
    return chan << bf->offset;
}

   //s3c_lcd->screen_base  = ;  /* 显存的虚拟地址 */
    s3c_lcd->screen_size   = **/;    //显存的大小    

 /* 3. 硬件相关的操作 */
/* 3.1 配置GPIO用于LCD */
/*定义*/
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;

    gpbcon = ioremap(0x56000010, );
    gpbdat = gpbcon+;
    gpccon = ioremap(0x56000020, );
    gpdcon = ioremap(0x56000030, );
    gpgcon = ioremap(0x56000060, );
    *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 &= ~();  /* GPB0设置为输出引脚 */
    *gpbcon |= ;
    *gpbdat &= ~;     /* 输出低电平 */
    *gpgcon |= (<<); /* 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 */
static volatile struct lcd_regs* lcd_regs;    //定义

    lcd_regs = ioremap(0x4D000000, sizeof(struct lcd_regs));
/*****LCD寄存器*****/
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[];
    unsigned long    dithmode;
    unsigned long    tpal;
    unsigned long    lcdintpnd;
    unsigned long    lcdsrcpnd;
    unsigned long    lcdintmsk;
    unsigned long    lpcsel;
};

/* 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  = (<<) | (<<) | (0x0c<<);

/* 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
     *             4.3寸液晶屏手册
     *             VBPD=1     tvb=2
     * bit[23:14]: 多少行, 272, 所以LINEVAL=272-1=271    tvd=272
     * bit[13:6] : VFPD, 发出最后一行数据之后，再过多长时间才发出VSYNC
     *           4.3寸液晶屏手册 VFPD=2-1=1    tvf=2
     * bit[5:0]  : VSPW, VSYNC信号的脉冲宽度, VSPW=10-1=9   tvp=10
     */
    lcd_regs->lcdcon2  = (<<) | (<<) | (<<) | ();

/* 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
     *            4.3寸液晶屏手册
     *             HBPD=1      thb=2
     * bit[18:8]: 多少列,480, 所以HOZVAL=480-1=479      thd=480
     * 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
     *           4.3寸液晶屏手册  HFPD=2-1=1    thf=2
     */
    lcd_regs->lcdcon3 = (<<) | (<<) | ();

/* 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=41-1=40
     */
    lcd_regs->lcdcon4 = ;

/* 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 = (<<) | (<<) | (<<) | (<<) | (<<);
/* 3.3 分配显存(framebuffer), 并把地址告诉LCD控制器 */
//s3c_lcd->screen_base   /* 显存的虚拟地址 */
//s3c_lcd->fix.smem_start = xxx;  /* 显存的物理地址 */
  s3c_lcd->screen_base = dma_alloc_writecombine(NULL, s3c_lcd->fix.smem_len, &s3c_lcd->fix.smem_start, GFP_KERNEL);
/*帧缓冲开始地址1寄存器
  *
  */
lcd_regs->lcdsaddr1  = (s3c_lcd->fix.smem_start >> ) & ~(<<);        //1~30，开始地址
lcd_regs->lcdsaddr2  = ((s3c_lcd->fix.smem_start + s3c_lcd->fix.smem_len) >> ) & 0x1fffff;    //从1开始，结束地址
lcd_regs->lcdsaddr3  = (*/);  /* 一行的长度(单位: 2字节) */
/* 启动LCD */
    lcd_regs->lcdcon1 |= (<<); /* 使能LCD控制器 */
    lcd_regs->lcdcon5 |= (<<); /* 使能LCD本身 */
    *gpbdat |= ;     /* 输出高电平, 使能背光 */
/* 4. 注册 */
    register_framebuffer(s3c_lcd);
-------------------------------------------------------------------

lcd_exit:
unregister_framebuffer(s3c_lcd);
    lcd_regs->lcdcon1 &= ~(<<); /* 关闭LCD本身 */
    *gpbdat &= ~;     /* 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);

假设
app: open("/dev/fb0", ...) 主设备号: 29, 次设备号: 0
--------------------------------------------------------------
kernel:
fb_open
int fbidx = iminor(inode);
struct fb_info *info = = registered_fb[0];

app: read()
---------------------------------------------------------------
kernel:
fb_read
int fbidx = iminor(inode);
struct fb_info *info = registered_fb[fbidx];
if (info->fbops->fb_read)
return info->fbops->fb_read(info, buf, count, ppos);
src = (u32 __iomem *) (info->screen_base + p);
dst = buffer;
*dst++ = fb_readl(src++);
copy_to_user(buf, buffer, c)

问1. registered_fb在哪里被设置？
答1. register_framebuffer

怎么写LCD驱动程序？
1. 分配一个fb_info结构体: framebuffer_alloc
2. 设置
3. 注册: register_framebuffer
4. 硬件相关的操作

测试：
1. make menuconfig去掉原来的驱动程序
-> Device Drivers
-> Graphics support
<M> S3C2410 LCD framebuffer support

2. make uImage
make modules

3. 使用新的uImage启动开发板:

4.
insmod cfbcopyarea.ko
insmod cfbfillrect.ko
insmod cfbimgblt.ko
insmod lcd.ko

echo hello > /dev/tty1 // 可以在LCD上看见hello
cat lcd.ko > /dev/fb0 // 花屏

5. 修改 /etc/inittab
tty1::askfirst:-/bin/sh
用新内核重启开发板

insmod cfbcopyarea.ko
insmod cfbfillrect.ko
insmod cfbimgblt.ko
insmod lcd.ko
insmod buttons.ko