jz2440_lcd

驅動程式中：
lcd_init:
---------------------------------------------------------
static struct fb_info *s3c_lcd;    //定義一個結構體
/* 1. 分配一個fb_info */
    s3c_lcd = framebuffer_alloc(0, NULL);    //不需要額外的空間

--------------------3.4.2內核中的函數-----------------------------------------
struct fb_info {
struct fb_var_screeninfo var;    /* Current var可變參數 */
struct fb_fix_screeninfo fix;      /* Current fix 固定參數*/
struct fb_ops *fbops;                /*操作參數*/
void *pseudo_palette;        /* Fake palette of 16 colors 其他設置*/
unsigned long screen_size;    /* Amount of ioremapped VRAM or 0顯存的大小 */
}
-----------------------------------------------------------------------------
/* 2. 設置 */
/* 2.1 設置固定的參數 */
strcpy(s3c_lcd->fix.id, "mylcd");                //名字
    s3c_lcd->fix.smem_len = 480*272*16/8;        //顯存的長度
    s3c_lcd->fix.type     = FB_TYPE_PACKED_PIXELS;    //看不懂預設0
    s3c_lcd->fix.visual   = FB_VISUAL_TRUECOLOR; /* TFT (真彩色)*/
    s3c_lcd->fix.line_length = 480*2;    //長度*2個位元組

--------------------3.4.2內核中的函數-----------------------------------------

   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_*        */
    __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[2];        /* Reserved for future compatibility */
};
 ---------------------------------------------------------------------  
/* 2.2 設置可變的參數 */
s3c_lcd->var.xres           = 480;    //x方向的解析度
    s3c_lcd->var.yres           = 272;    //y方向的解析度
    s3c_lcd->var.xres_virtual   = 480;    //x方向的虛擬解析度
    s3c_lcd->var.yres_virtual   = 272;    //y方向的虛擬解析度
    s3c_lcd->var.bits_per_pixel = 16;        //每個像素用多少位
    /* RGB:565 */
    s3c_lcd->var.red.offset     = 11;    //從那位開始    
    s3c_lcd->var.red.length     = 5;    //長度
    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;

--------------------3.4.2內核中的函數-----------------------------------------

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[4];        /* Reserved for future compatibility */
};
---------------------------------------------------------------------
/* 2.3 設置操作函數 */
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 其他的設置 */
   static u32 pseudo_palette[16];            //定義
    s3c_lcd->pseudo_palette = pseudo_palette;        //調色板

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 > 16)
        return 1;
    /* 用red,green,blue三原色構造出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;
}
/* 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;
}

   //s3c_lcd->screen_base  = ;  /* 顯存的虛擬地址 */
    s3c_lcd->screen_size   = 480*272*16/8;    //顯存的大小    

 /* 3. 硬體相關的操作 */
/* 3.1 配置GPIO用於LCD */
/*定義*/
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, 8);
    gpbdat = gpbcon+1;
    gpccon = ioremap(0x56000020, 4);
    gpdcon = ioremap(0x56000030, 4);
    gpgcon = ioremap(0x56000060, 4);
    *gpccon  = 0xaaaaaaaa;   /* GPIO管腳用於VD[7:0],LCDVF[2:0],VM,VFRAME,VLINE,VCLK,LEND */
    *gpdcon  = 0xaaaaaaaa;   /* GPIO管腳用於VD[23:8] */
    *gpbcon &= ~(3);  /* GPB0設置為輸出引腳 */
    *gpbcon |= 1;
    *gpbdat &= ~1;     /* 輸出低電平 */
    *gpgcon |= (3<<8); /* GPG4用作LCD_PWREN */
/* 3.2 根據LCD手冊設置LCD控制器, 比如VCLK的頻率等 */
static volatile struct lcd_regs* lcd_regs;    //定義

    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[9];
    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手冊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);
    
/* 垂直方向的時間參數
     * bit[31:24]: VBPD, VSYNC之後再過多長時間才能發出第1行數據
     *             4.3寸液晶屏手冊
     *             VBPD=1     tvb=2
     * bit[23:14]: 多少行, 272, 所以LINEVAL=272-1=271    tvd=272
     * bit[13:6] : VFPD, 發出最後一行數據之後，再過多長時間才發出VSYNC
     *           4.3寸液晶屏手冊 VFPD=2-1=1    tvf=2    
     * bit[5:0]  : VSPW, VSYNC信號的脈衝寬度, VSPW=10-1=9   tvp=10
     */
    lcd_regs->lcdcon2  = (1<<24) | (271<<14) | (1<<6) | (9);

/* 水平方向的時間參數
     * bit[25:19]: HBPD, VSYNC之後再過多長時間才能發出第1行數據
     *            4.3寸液晶屏手冊
     *             HBPD=1      thb=2
     * bit[18:8]: 多少列,480, 所以HOZVAL=480-1=479      thd=480
     * bit[7:0] : HFPD, 發出最後一行里最後一個象素數據之後，再過多長時間才發出HSYNC
     *           4.3寸液晶屏手冊  HFPD=2-1=1    thf=2       
     */
    lcd_regs->lcdcon3 = (1<<19) | (479<<8) | (1);

/* 水平方向的同步信號
     * bit[7:0]    : HSPW, HSYNC信號的脈衝寬度, LCD手冊T7=5, 所以HSPW=41-1=40
     */    
    lcd_regs->lcdcon4 = 40;

/* 信號的極性
     * bit[11]: 1=565 format
     * bit[10]: 0 = The video data is fetched at VCLK falling edge
     * bit[9] : 1 = HSYNC信號要反轉,即低電平有效
     * bit[8] : 1 = VSYNC信號要反轉,即低電平有效
     * bit[6] : 0 = VDEN不用反轉
     * bit[3] : 0 = PWREN輸出0
     * bit[1] : 0 = BSWP
     * bit[0] : 1 = HWSWP 2440手冊P413
     */
    lcd_regs->lcdcon5 = (1<<11) | (0<<10) | (1<<9) | (1<<8) | (1<<0);
/* 3.3 分配顯存(framebuffer), 並把地址告訴LCD控制器 */
//s3c_lcd->screen_base   /* 顯存的虛擬地址 */
//s3c_lcd->fix.smem_start = xxx;  /* 顯存的物理地址 */
  s3c_lcd->screen_base = dma_alloc_writecombine(NULL, s3c_lcd->fix.smem_len, &s3c_lcd->fix.smem_start, GFP_KERNEL);            
/*幀緩衝開始地址1寄存器
  *  
  */
lcd_regs->lcdsaddr1  = (s3c_lcd->fix.smem_start >> 1) & ~(3<<30);        //1~30，開始地址
lcd_regs->lcdsaddr2  = ((s3c_lcd->fix.smem_start + s3c_lcd->fix.smem_len) >> 1) & 0x1fffff;    //從1開始，結束地址
lcd_regs->lcdsaddr3  = (480*16/16);  /* 一行的長度(單位: 2位元組) */         
/* 啟動LCD */
    lcd_regs->lcdcon1 |= (1<<0); /* 使能LCD控制器 */
    lcd_regs->lcdcon5 |= (1<<3); /* 使能LCD本身 */
    *gpbdat |= 1;     /* 輸出高電平, 使能背光 */     
/* 4. 註冊 */
    register_framebuffer(s3c_lcd);
-------------------------------------------------------------------


lcd_exit:
unregister_framebuffer(s3c_lcd);
    lcd_regs->lcdcon1 &= ~(1<<0); /* 關閉LCD本身 */
    *gpbdat &= ~1;     /* 關閉背光 */
    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);

假設
app: open("/dev/fb0", ...) 主設備號: 29, 次設備號: 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)

問1. registered_fb在哪裡被設置？
答1. register_framebuffer

怎麼寫LCD驅動程式？
1. 分配一個fb_info結構體: framebuffer_alloc
2. 設置
3. 註冊: register_framebuffer
4. 硬體相關的操作

測試：
1. make menuconfig去掉原來的驅動程式
-> Device Drivers
-> Graphics support
<M> S3C2410 LCD framebuffer support

2. make uImage
make modules

3. 使用新的uImage啟動開發板:

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

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

5. 修改 /etc/inittab
tty1::askfirst:-/bin/sh
用新內核重啟開發板

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