OK6410内核驱动分析

一. 理论分析
1. 几个概念:
FIMC :
    Fully Interactive Mobile Camera （完全交互式移动摄像机）
FIMD: 
    Fully Interactive Mobile Display （完全交互式移动显示设备）
2. 设置VCLK
在VIDCON0中
bit[3:2]-->Select the Video Clock source =00 --> HCLK=133MHZ
bit[13:6] --> CLKVAL_F = 13  (这个值是在驱动中计算出来的)
VCLK = Video Clock Source / (CLKVAL+1) where CLKVAL >= 1
         = 133MHZ / (13+1) = 9.5MHZ
3. 刷新频率计算
Frame Rate  = VCLK / (HSPW + HBPD + HOZVAL + HFPD) / (VSPW + VBPD + LINEVAL + VFPD)
            = 9.5MHZ/(2+41+2+480)/(2+272+10+2)
            =0.00006327MHZ
            =63HZ

二. 驱动分析
首先在平台的目录中定义platform_device
在arch/arm/plat-samsung/dev-fb.c中

static struct resource s3c_fb_resource[] = {
    [0] = {
        .start = S3C_PA_FB,
        .end = S3C_PA_FB + SZ_16K - 1,
        .flags = IORESOURCE_MEM,
    },
    [1] = {
        .start = IRQ_LCD_VSYNC,
        .end = IRQ_LCD_VSYNC,
        .flags = IORESOURCE_IRQ,
    },
    [2] = {
        .start = IRQ_LCD_FIFO,
        .end = IRQ_LCD_FIFO,
        .flags = IORESOURCE_IRQ,
    },
    [3] = {
        .start = IRQ_LCD_SYSTEM,
        .end = IRQ_LCD_SYSTEM,
        .flags = IORESOURCE_IRQ,
    },
};

struct platform_device s3c_device_fb = {
    .name         = "s3c-fb",
    .id         = -1,
    .num_resources     = ARRAY_SIZE(s3c_fb_resource),
    .resource     = s3c_fb_resource,
    .dev.dma_mask     = &s3c_device_fb.dev.coherent_dma_mask,
    .dev.coherent_dma_mask = 0xffffffffUL,
};

然后在驱动的probe函数中:
在driver/video/samsun/s3cfb.c中

static int __init s3cfb_probe(struct platform_device *pdev)
{
    struct resource *res;
    struct fb_info *fbinfo;
    s3cfb_info_t *info;

    char driver_name[] = "s3cfb";
    int index = 0, ret, size;
    //分配sizeof(fb_info+私有成员)大小的内存,使par指向s3cfb_info_t结构体
    fbinfo = framebuffer_alloc(sizeof(s3cfb_info_t), &pdev->dev);

    platform_set_drvdata(pdev, fbinfo);

    info = fbinfo->par;                //私有数据是一个结构体s3cfb_info_t
    info->dev = &pdev->dev;

    //获取LCD的io端口,并映射
    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    size = (res->end - res->start) + 1;
    info->mem = request_mem_region(res->start, size, pdev->name);
    info->io = ioremap(res->start, size);

    s3cfb_pre_init();                                 //2.使能中断寄存器,s3cfb_fimd的第一次初始化
    s3cfb_set_backlight_power(1);                     //设置backlight_power = 1;
    s3cfb_set_lcd_power(1);                           //设置lcd_power = 1;
    s3cfb_set_backlight_level(S3CFB_DEFAULT_BACKLIGHT_LEVEL); //设置backlight_level = 2;

    //获取时钟,并使能
    info->clk = clk_get(NULL, "lcd");     //133.000Mhz,使用的是HCLK
    clk_enable(info->clk);

    s3cfb_fimd.vsync_info.count = 0;
    init_waitqueue_head(&s3cfb_fimd.vsync_info.wait_queue);

    //申请中断
    res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
    ret = request_irq(res->start, s3cfb_irq, 0, "s3c-lcd", pdev);
    msleep(5);
    //对4个framebuffer分别初始化
    for (index = 0; index < S3CFB_NUM; index++) {
        s3cfb_info[index].mem = info->mem;
        s3cfb_info[index].io = info->io;
        s3cfb_info[index].clk = info->clk;

        s3cfb_init_fbinfo(&s3cfb_info[index], driver_name, index);  //3.初始化fbinfo
        ret = s3cfb_map_video_memory(&s3cfb_info[index]);           //4.分配dma内存

        ret = s3cfb_init_registers(&s3cfb_info[index]);            //5.写寄存器
        ret = s3cfb_check_var(&s3cfb_info[index].fb.var, &s3cfb_info[index].fb);  //6.设置var范围

        if (index < 2){
            if (fb_alloc_cmap(&s3cfb_info[index].fb.cmap, 256, 0) < 0)     //7.申请color map
                goto dealloc_fb;
        } else {
            if (fb_alloc_cmap(&s3cfb_info[index].fb.cmap, 16, 0) < 0)
                goto dealloc_fb;
        }

        ret = register_framebuffer(&s3cfb_info[index].fb);                 //8.注册framebuffer
    }

    ret = device_create_file(&(pdev->dev), &dev_attr_backlight_power);
    ret = device_create_file(&(pdev->dev), &dev_attr_backlight_level);
    ret = device_create_file(&(pdev->dev), &dev_attr_lcd_power);
    return 0;
}

1.分配内存
分配fb_info+size大小的内存,并使par指向私有数据size

struct fb_info *framebuffer_alloc(size_t size, struct device *dev)
{
    fb_info_size += PADDING;          //加上PADDING是让私有数据4字节对齐
    char *p = kzalloc(fb_info_size + size, GFP_KERNEL);

    struct fb_info * info = (struct fb_info *) p;
    info->par = p + fb_info_size;     //par指向私有数据
    info->device = dev;
    return info;                      //返回申请内存的首指针
}

2. 初始化视频中断控制寄存器0
在drivers/video/samsun/s3cfb_fimd4x.c中

void s3cfb_pre_init(void)
{
    //Video Frame Interrupt 0 at start of VSYNC,并使能
    s3cfb_fimd.vidintcon0 &= ~S3C_VIDINTCON0_FRAMESEL0_MASK;
    s3cfb_fimd.vidintcon0 |= S3C_VIDINTCON0_FRAMESEL0_VSYNC;
    s3cfb_fimd.vidintcon0 |= S3C_VIDINTCON0_INTFRMEN_ENABLE;
   //0x9021=1001 0000 0010 0001
   //打开video 中断,关闭fifo 中断
   //打开 video frame 中断, Video Frame Interrupt 0 at start of VSYNC    writel(s3cfb_fimd.vidintcon0, S3C_VIDINTCON0);
}

在driver/vidoe/samsun/s3cfb.c中

static void s3cfb_set_lcd_power(int to)
{
    s3cfb_fimd.lcd_power = to;
}

static void s3cfb_set_backlight_power(int to)
{
    s3cfb_fimd.backlight_power = to;
}

static void s3cfb_set_backlight_level(int to)
{
    s3cfb_fimd.backlight_level = to;
}

3. 初始化s3cfb_info_t结构体
在driver/vidoe/samsun/s3cfb.c中

static void s3cfb_init_fbinfo(s3cfb_info_t *finfo, char *drv_name, int index)
{
    int i = 0;
    if (index == 0)
    {
        if(lcdsize == 1)
            s3cfb_init_hw_43();        //3.1 s3cfb_fimd及gpio的初始化
    }
    strcpy(finfo->fb.fix.id, drv_name);
    //下面一大段就是要将初始化好后的s3cfb_fimd赋给finfo,类似于结构体转化
    finfo->win_id = index;
    finfo->fb.fix.type = FB_TYPE_PACKED_PIXELS;
    finfo->fb.fix.type_aux = 0;
    finfo->fb.fix.xpanstep = 0;
    finfo->fb.fix.ypanstep = 1;
    finfo->fb.fix.ywrapstep = 0;
    finfo->fb.fix.accel = FB_ACCEL_NONE;

    finfo->fb.fbops = &s3cfb_ops;                //fb操作函数
    finfo->fb.flags    = FBINFO_FLAG_DEFAULT;

    finfo->fb.pseudo_palette = &finfo->pseudo_pal;

    finfo->fb.var.nonstd = 0;
    finfo->fb.var.activate = FB_ACTIVATE_NOW;
    finfo->fb.var.accel_flags = 0;
    finfo->fb.var.vmode = FB_VMODE_NONINTERLACED;

    finfo->fb.var.xoffset = s3cfb_fimd.xoffset;     //xoffset=0
    finfo->fb.var.yoffset = s3cfb_fimd.yoffset;     //yoffset=0

    if (index == 0) {
        finfo->fb.var.height = s3cfb_fimd.height;   //height=272
        finfo->fb.var.width = s3cfb_fimd.width;     //width=480

        finfo->fb.var.xres = s3cfb_fimd.xres;       //xres=480
        finfo->fb.var.yres = s3cfb_fimd.yres;       //yres=272

        finfo->fb.var.xres_virtual = s3cfb_fimd.xres_virtual;  //xres_virtual=480
        finfo->fb.var.yres_virtual = s3cfb_fimd.yres_virtual;  //yres_virtual=544
    } else {
        finfo->fb.var.height = s3cfb_fimd.osd_height;      //osd_height=272
        finfo->fb.var.width = s3cfb_fimd.osd_width;        //osd_height=480

        finfo->fb.var.xres = s3cfb_fimd.osd_xres;         //osd_xres=480
        finfo->fb.var.yres = s3cfb_fimd.osd_yres;         //osd_yres=272

        finfo->fb.var.xres_virtual = s3cfb_fimd.osd_xres_virtual;     //osd_xres_virtual=480
        finfo->fb.var.yres_virtual = s3cfb_fimd.osd_yres_virtual;     //osd_yres_virtaul=272
    }

    finfo->fb.var.bits_per_pixel = s3cfb_fimd.bpp;               //16
    finfo->fb.var.pixclock = s3cfb_fimd.pixclock;                //9009000
    finfo->fb.var.hsync_len = s3cfb_fimd.hsync_len;              //41
    finfo->fb.var.left_margin = s3cfb_fimd.left_margin;          //2
    finfo->fb.var.right_margin = s3cfb_fimd.right_margin;        //2
    finfo->fb.var.vsync_len = s3cfb_fimd.vsync_len;              //10
    finfo->fb.var.upper_margin = s3cfb_fimd.upper_margin;        //2
    finfo->fb.var.lower_margin = s3cfb_fimd.lower_margin;        //2
    finfo->fb.var.sync = s3cfb_fimd.sync;                        //0
    finfo->fb.var.grayscale = s3cfb_fimd.cmap_grayscale;         //0
    //480*544*2=522240
    finfo->fb.fix.smem_len = finfo->fb.var.xres_virtual * finfo->fb.var.yres_virtual * s3cfb_fimd.bytes_per_pixel;
    finfo->fb.fix.line_length = finfo->fb.var.width * s3cfb_fimd.bytes_per_pixel;    //480*2=960

    for (i = 0; i < 256; i++)
        finfo->palette_buffer[i] = S3CFB_PALETTE_BUFF_CLEAR;       //(0x80000000)
}

3.1 初始化s3cfb_fimd及gpio的初始化
在drviers/video/samsung/s3cfb_WXCAT43.c中

void s3cfb_init_hw_43(void)
{
    s3cfb_set_fimd_info();  //3.1.1 s3cfb_fimd的第二次初始化
    s3cfb_set_gpio();       //3.1.2 gpio口初始化
}

3.1.1 s3cfb_fimd结构体的第二次初始化
s3cfb_probe
--> s3cfb_init_fbinfo
    --> s3cfb_init_hw_43
    --> s3cfb_set_fimd_info

static void s3cfb_set_fimd_info(void)
{
// bit[7]= 0: RGB type LCD driver gets the video data at VCLK falling edge,下降沿获取数据
// bit[6]= 1: HSYNC 极性反转
// bit[5]= 1: VSYNC 极性反转
// bit[4]= 0: VDEN 极性不变
    s3cfb_fimd.vidcon1 = S3C_VIDCON1_IHSYNC_INVERT | S3C_VIDCON1_IVSYNC_INVERT | S3C_VIDCON1_IVDEN_NORMAL;  //0x60
//VBPDE[31-24]=0x0
//VBPD[23-16]=0x01
//VFPD[15-8]=0x01
//VSPW[7-0]=0x09
    s3cfb_fimd.vidtcon0 = S3C_VIDTCON0_VBPD(S3CFB_VBP - 1) | S3C_VIDTCON0_VFPD(S3CFB_VFP - 1) | S3C_VIDTCON0_VSPW(S3CFB_VSW - 1); //0x10109
//HBPDE[31-24]=0x0
//HBPD[23-16]=0x01
//HFPD[15-8]=0x01
//HSPW[7-0]=0x28=40
    s3cfb_fimd.vidtcon1 = S3C_VIDTCON1_HBPD(S3CFB_HBP - 1) | S3C_VIDTCON1_HFPD(S3CFB_HFP - 1) | S3C_VIDTCON1_HSPW(S3CFB_HSW - 1); //0x10128
//LINEVAL[21-11]=(Vertical display size)–1=10F=271
//HOZVAL[10-0] = (Horizontal display size)-1=1DF=479
    s3cfb_fimd.vidtcon2 = S3C_VIDTCON2_LINEVAL(S3CFB_VRES - 1) | S3C_VIDTCON2_HOZVAL(S3CFB_HRES - 1);                             //0x879df
//OSD_LeftTopX_F[21-11] = 0
//OSD_LeftTopY_F[10-0] = 0          window_0左上角的坐标是(0,0)
    s3cfb_fimd.vidosd0a = S3C_VIDOSDxA_OSD_LTX_F(0) | S3C_VIDOSDxA_OSD_LTY_F(0);                                                  //0x0
//OSD_RightBotX_F[21-11] = 0x1DF=479
//OSD_RightBotY_F[10-0] = 0x10f =271   window_0右下角的坐标是(479,271)
    s3cfb_fimd.vidosd0b = S3C_VIDOSDxB_OSD_RBX_F(S3CFB_HRES - 1) | S3C_VIDOSDxB_OSD_RBY_F(S3CFB_VRES - 1);                        //0xef90f
//OSD_LeftTopX_F[21-11] = 0
//OSD_LeftTopY_F[10-0] = 0         window_1左上角的坐标是(0,0)
    s3cfb_fimd.vidosd1a = S3C_VIDOSDxA_OSD_LTX_F(0) | S3C_VIDOSDxA_OSD_LTY_F(0);                                                  //0x0
//OSD_RightBotX_F[21-11] = 0x1DF=479
//OSD_RightBotY_F[10-0] = 0x10f =271   window_1右下角的坐标是(479,271)
    s3cfb_fimd.vidosd1b = S3C_VIDOSDxB_OSD_RBX_F(S3CFB_HRES_OSD - 1) | S3C_VIDOSDxB_OSD_RBY_F(S3CFB_VRES_OSD - 1);                //0xef90f

    s3cfb_fimd.width = S3CFB_HRES;                 //480
    s3cfb_fimd.height = S3CFB_VRES;                //272
    s3cfb_fimd.xres = S3CFB_HRES;                  //480
    s3cfb_fimd.yres = S3CFB_VRES;                  //272

    //定义了(CONFIG_FB_S3C_EXT_VIRTUAL_SCREEN)
    s3cfb_fimd.xres_virtual = S3CFB_HRES_VIRTUAL;  //如果定义了Virtual_screen则为480*544
    s3cfb_fimd.yres_virtual = S3CFB_VRES_VIRTUAL;  //如果没有定义Virtual_screen则为480*272

    s3cfb_fimd.osd_width = S3CFB_HRES_OSD;         //480
    s3cfb_fimd.osd_height = S3CFB_VRES_OSD;        //272
    s3cfb_fimd.osd_xres = S3CFB_HRES_OSD;          //480
    s3cfb_fimd.osd_yres = S3CFB_VRES_OSD;          //272

    s3cfb_fimd.osd_xres_virtual = S3CFB_HRES_OSD;    //480
    s3cfb_fimd.osd_yres_virtual = S3CFB_VRES_OSD;    //272

    s3cfb_fimd.pixclock = S3CFB_PIXEL_CLOCK;         //9009000

    s3cfb_fimd.hsync_len = S3CFB_HSW;                //41
    s3cfb_fimd.vsync_len = S3CFB_VSW;                //10
    s3cfb_fimd.left_margin = S3CFB_HFP;              //2
    s3cfb_fimd.upper_margin = S3CFB_VFP;             //2
    s3cfb_fimd.right_margin = S3CFB_HBP;             //2
    s3cfb_fimd.lower_margin = S3CFB_VBP;             //2
}

小总结一下:
全局变量s3cfb_fimd_info_t s3cfb_fimd
首先定义在drivers/video/samsun/s3cfb_fimd4x.c中

第1次初始化 
s3cfb_probe
    --> s3cfb_pre_init();
打开video 中断,关闭fifo 中断
打开 video frame 中断, Video Frame Interrupt 0 at start of VSYNC

第2次初始化
s3cfb_probe
--> s3cfb_init_fbinfo
--> s3cfb_init_hw_43
    --> s3cfb_set_fimd_info

3.1.2 gpio口初始化
在

int s3cfb_set_gpio(void)
{
    //将HCLK clock gating control寄存器0x7E00_F030的bit3设为1,即使能LCD的时钟
    val = readl(S3C_HCLK_GATE);
    val |= S3C_CLKCON_HCLK_LCD;
    writel(val, S3C_HCLK_GATE);
    //设置Special PortControl Register寄存器0x7F0081A0的bit[0-1]设为01,即RGB I/F style
    val = readl(S3C64XX_SPCON);
    val &= ~0x3;
    val |= (1 << 0);
    writel(val, S3C64XX_SPCON);

    //VD[0-15]连在了GPI[0-15]上,所以要把GPI口配成LCD
    for (i = 0; i < 16; i++)
        s3c_gpio_cfgpin(S3C64XX_GPI(i), S3C_GPIO_SFN(2));

    //VD[16-23]连在了GPJ[0-7]上,所以要把GPJ口配成LCD
    //HSYNC-->GPJ8, VSYNC-->GPJ9, VDEN-->GPJ10, VCLK-->GPJ11
    for (i = 0; i < 12; i++)
        s3c_gpio_cfgpin(S3C64XX_GPJ(i), S3C_GPIO_SFN(2));
    //ok6410跟GPE0好像没有什么关系,这儿可以去掉
    if (gpio_is_valid(S3C64XX_GPE(0))) {
        err = gpio_request(S3C64XX_GPE(0), "GPE");
        gpio_direction_output(S3C64XX_GPE(0), 1);
    }
    gpio_set_value(S3C64XX_GPE(0), 1);
    gpio_free(S3C64XX_GPE(0));
    gpio_free(S3C64XX_GPF(14));
    return 0;
}

4. 分配DMA内存
第1个window,双缓冲 0x7f8000=320*240*3*2
FB1: map_video_memory: dma=5f180000 cpu=ff600000 size=0007f800
Window[0] - FB2: map_video_memory: dma=5f1bfc00 cpu=ff63fc00 size=0003fc00
第2个window,双缓冲
FB1: map_video_memory: dma=5f200000 cpu=ff700000 size=0007f800
Window[1] - FB2: map_video_memory: dma=5f23fc00 cpu=ff73fc00 size=0003fc00

在drivers/vidoe/samsun/s3cfb.c中

static int __init s3cfb_map_video_memory(s3cfb_info_t *fbi)
{
    fbi->map_size_f1 = PAGE_ALIGN(fbi->fb.fix.smem_len);    //480*272*n对齐到4K
    //index=0时在DMA空间分配480*272*4=0x7f800=对齐后0x80000大小的DMA内存
    //index=1,2,3时在DMA空间分配480*272*2=0x3fc00=对齐后0x40000大小的DMA内存
    fbi->map_cpu_f1 = dma_alloc_writecombine(fbi->dev, fbi->map_size_f1, &fbi->map_dma_f1, GFP_KERNEL); //分配dma内存
    fbi->map_size_f1 = fbi->fb.fix.smem_len;                //480*272*n原始大小,不对齐到4K

    if (fbi->map_cpu_f1) {                                  //map_cpu_f1是将dma映射到虚拟内存空间的地址
        memset(fbi->map_cpu_f1, 0xf0, fbi->map_size_f1);    //初始化成0xf0?这儿为什么不是0?
        fbi->screen_dma_f1 = fbi->map_dma_f1;
        fbi->fb.screen_base = fbi->map_cpu_f1;
        fbi->fb.fix.smem_start = fbi->screen_dma_f1;
    }
    //下面的指针指向第二个 buffer
#if defined(CONFIG_FB_S3C_EXT_DOUBLE_BUFFERING)
    if (fbi->win_id<2 && fbi->map_cpu_f1) {
        fbi->map_size_f2 = (fbi->fb.fix.smem_len / 2);
        fbi->map_cpu_f2 = fbi->map_cpu_f1 + fbi->map_size_f2;
        fbi->map_dma_f2 = fbi->map_dma_f1 + fbi->map_size_f2;
        fbi->screen_dma_f2 = fbi->map_dma_f2;
    }
#endif
    return 0;
}

注: void *dma_alloc_writecombine(struct device *, size_t, dma_addr_t *, gfp_t);
          arg1是设备名
          arg2是分配dma buffer的长度
          arg3是分配dma的物理地址,利用指针改写
          arg4是标志GFP_KERNEL
          ret 返回分配dma的虚拟地址
ret 与 arg3都指向同一块内存,只不过argc3是物理地址,ret是虚拟地址.
dma_alloc_coherent: 禁止页表项中的C(cacheable)以及B(bufferable)域
dma_alloc_writecombine只是禁止C(Cacheable)域.即不使用cache
5. 写寄存器
在driver/video/samsun中

int s3cfb_init_registers(s3cfb_info_t *fbi)
{
    struct clk *lcd_clock;
    struct fb_var_screeninfo *var = &fbi->fb.var;
    unsigned long flags = 0, page_width = 0, offset = 0;
    unsigned long video_phy_temp_f1 = fbi->screen_dma_f1;
    unsigned long video_phy_temp_f2 = fbi->screen_dma_f2;
    int win_num = fbi->win_id;

    local_irq_save(flags);           //关中断,并保存

    page_width = var->xres * s3cfb_fimd.bytes_per_pixel;                     //page_width=960
    offset = (var->xres_virtual - var->xres) * s3cfb_fimd.bytes_per_pixel;   //offset=0
    if (win_num == 0) {
        s3cfb_fimd.vidcon0 = s3cfb_fimd.vidcon0 & ~(S3C_VIDCON0_ENVID_ENABLE | S3C_VIDCON0_ENVID_F_ENABLE);
        writel(s3cfb_fimd.vidcon0, S3C_VIDCON0);     //设置lcd的clk分频-->Divided by CLKVAL_F

        lcd_clock = clk_get(NULL, "lcd");
        s3cfb_fimd.vidcon0 |= S3C_VIDCON0_CLKVAL_F((int) ((clk_get_rate(lcd_clock) / s3cfb_fimd.pixclock) - 1));
//lcd_clock->rate=13M, s3cfb_fimd.pixclock=9M, s3cfb_fimd.vidcon0[13-6]=13
#if defined(CONFIG_FB_S3C_EXT_VIRTUAL_SCREEN)
        offset = 0;
        s3cfb_fimd.vidw00add0b0 = video_phy_temp_f1;
        s3cfb_fimd.vidw00add0b1 = video_phy_temp_f2;
        s3cfb_fimd.vidw00add1b0 = S3C_VIDWxxADD1_VBASEL_F((unsigned long) video_phy_temp_f1 + (page_width + offset) * (var->yres));
        s3cfb_fimd.vidw00add1b1 = S3C_VIDWxxADD1_VBASEL_F((unsigned long) video_phy_temp_f2 + (page_width + offset) * (var->yres));
#endif
     }

    writel(video_phy_temp_f1, S3C_VIDW00ADD0B0 + (0x08 * win_num));
    writel(S3C_VIDWxxADD1_VBASEL_F((unsigned long) video_phy_temp_f1 + (page_width + offset) * (var->yres)), S3C_VIDW00ADD1B0 + (0x08 * win_num));
    writel(S3C_VIDWxxADD2_OFFSIZE_F(offset) | (S3C_VIDWxxADD2_PAGEWIDTH_F(page_width)), S3C_VIDW00ADD2 + (0x04 * win_num));

    if (win_num < 2) {
        writel(video_phy_temp_f2, S3C_VIDW00ADD0B1 + (0x08 * win_num));
        writel(S3C_VIDWxxADD1_VBASEL_F((unsigned long) video_phy_temp_f2 + (page_width + offset) * (var->yres)), S3C_VIDW00ADD1B1 + (0x08 * win_num));
    }

    switch (win_num) {
    case 0:
        //wincon0=0x110014=0001 0001 0000 0000 0001 0100
        //bit[0]=video output disable --> 导致bit[22]=0
        //bit[5-2]=0101=16BPP (R5 G6 B5)
        //bit[10-9]=00 = DMA's Burst Max len 16word
        //bit[13] = 0 = input color space RGB
        //bit[16] = 1 = half wrod swap enabel
        //bit[20] = 1 = select buf 1
        writel(s3cfb_fimd.wincon0, S3C_WINCON0);

        //vidcon0=0x350=0011 0101 0000
        //bit[3-2]=00 = VideoClock source = HCLK
        //bit[4]=1=video clock Divided by CLKVAL_F
        //bit[13-6]=00 1101 = 13   HCLK/CLKVAL_F=133/13=10.230769231M
        writel(s3cfb_fimd.vidcon0, S3C_VIDCON0);

        //vidcon1=0x60 = 0110 0000
        //bit[4]= VDEN polarity noraml
        //bit[5]=VSYNC polarity inverted
        //bit[6]=HSYNC polarity inverted
        //bit[7]=gets the video data at vclk falling
        writel(s3cfb_fimd.vidcon1, S3C_VIDCON1);

        //vidtcon0=0x10109
        //VBPDE[31-24]= 0x0
        //VBPD[23-16]= 0x01
        //VFPD[15-8]= 0x01
        //VSPW[7-0]= 0x09
        writel(s3cfb_fimd.vidtcon0, S3C_VIDTCON0);

        //vidtcon1=0x10128
        //VFPDE[31-24]=0x0
        //HBPD[23-16]=0x01
        //HFPD[15-8]=0x01
        //HSPW[7-0]= 0x28=40
        writel(s3cfb_fimd.vidtcon1, S3C_VIDTCON1);

        //vidtcon2=0x879df
        //LINEVAL[21-11]=(Vertical display size)–1=10F=271        //HOZVAL[10-0] = (Horizontal display size)-1=1DF=479
        writel(s3cfb_fimd.vidtcon2, S3C_VIDTCON2);

        //dithmode=0x0
        //禁用dither
        writel(s3cfb_fimd.dithmode, S3C_DITHMODE);

        //vidintcon0=0x9021=0x1001 0000 0010 0001
        //bit[0]=Video Interrupt Enable
        //bit[1]=FIFO disable
        //bit[4-2]=FIFO int level =25
        //bit[11-5]=FIFO int -->win 0 control enable
        //bit[12]=video Frame interrupt enable
        //bit[14-13]=video frame int 1 start of None
        //bit[16-15]=video frame int 0 start of VSYNC
        writel(s3cfb_fimd.vidintcon0, S3C_VIDINTCON0);

        //vidintcon1=0x0
        //没看出什么用
        writel(s3cfb_fimd.vidintcon1, S3C_VIDINTCON1);

        //vidosd0a=0x0
        //window_0左上角坐标(0,0)
        writel(s3cfb_fimd.vidosd0a, S3C_VIDOSD0A);

        //vidosd0b=0xef90f
        //window_0右下角的坐标是(479,271)
        writel(s3cfb_fimd.vidosd0b, S3C_VIDOSD0B);

        //vidosd0c=0x0
        //bit[23-0]=Window Size = 竟然为0?
        writel(s3cfb_fimd.vidosd0c, S3C_VIDOSD0C);

        //wpalcon=0x6
        //
        //
        //
        writel(s3cfb_fimd.wpalcon, S3C_WPALCON);

        //
        s3cfb_onoff_win(fbi, ON);
        break;
    case 1-4:
        类推,省略.
        break;
    }

    local_irq_restore(flags);            //开中断,并恢复,于上面的local_irq_save正好相反

    return 0;
 }

6. 规定范围 

static int s3cfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
{
    s3cfb_info_t *fbi = (s3cfb_info_t *) info;
    switch (var->bits_per_pixel) {
        case 16:
            var->red = s3cfb_rgb_16.red;          //{.offset = 11, .length = 5,},
            var->green = s3cfb_rgb_16.green;      //{.offset = 5,  .length = 6,},
            var->blue = s3cfb_rgb_16.blue;        //{.offset = 0,  .length = 5,},
            var->transp = s3cfb_rgb_16.transp;    //{.offset = 0,  .length = 0,},
            s3cfb_fimd.bytes_per_pixel = 2;   //每个像素2个字节
            break;
    }
    //对窗口0进行特殊处理
    if( (fbi->win_id == 0) && (var->bits_per_pixel == 28) )
        var->transp.length = 0;

    return 0;
}

7. 分配并初始化color map 
fb_alloc_cmap(&s3cfb_info[index].fb.cmap, 256, 0);

int fb_alloc_cmap(struct fb_cmap *cmap, int len, int transp)
{
    return fb_alloc_cmap_gfp(cmap, len, transp, GFP_ATOMIC);
}

在driver/video/fbcmap.c中

int fb_alloc_cmap_gfp(struct fb_cmap *cmap, int len, int transp, gfp_t flags)
{
    int size = len * sizeof(u16);

    if (cmap->len != len) {
        fb_dealloc_cmap(cmap);               //把以前申请的rgb内存kfree掉
        cmap->red = kmalloc(size, flags);    //重新分配内存,GFP_ATOMIC
        cmap->green = kmalloc(size, flags);  //重新分配内存,GFP_ATOMIC
        cmap->blue = kmalloc(size, flags);   //重新分配内存,GFP_ATOMIC
        if (transp) {
            cmap->transp = kmalloc(size, flags);
        } else {
            cmap->transp = NULL;             //transp设为NULL
        }
    }
    cmap->start = 0;
    cmap->len = len;
    ret = fb_copy_cmap(fb_default_cmap(len), cmap);  //把default的cmap复制到新分配的cmap中
    return 0;
}

上层执行fb_set_par 
     -->  s3cfb_set_par

static int s3cfb_set_par(struct fb_info *info)
{
    //var->bits_per_pixel=16, s3cfb_fimd.bytes_per_pixel=2
    fbi->fb.fix.visual = FB_VISUAL_TRUECOLOR;
    fbi->fb.fix.line_length = var->width * s3cfb_fimd.bytes_per_pixel;
    s3cfb_activate_var(fbi, var);
    return 0;
}

上层执行fb_set_par 
     -->  s3cfb_set_par
    --> s3cfb_activate_var
根据像素位数设置寄存器.

void s3cfb_activate_var(s3cfb_info_t *fbi, struct fb_var_screeninfo *var)
{
    switch (var->bits_per_pixel) {
        case 16:
            s3cfb_fimd.wincon0 = S3C_WINCONx_HAWSWP_ENABLE | S3C_WINCONx_BURSTLEN_16WORD | S3C_WINCONx_BPPMODE_F_16BPP_565;
            s3cfb_fimd.wincon1 = S3C_WINCONx_HAWSWP_ENABLE | S3C_WINCONx_BURSTLEN_16WORD | S3C_WINCONx_BPPMODE_F_16BPP_565 | S3C_WINCONx_BLD_PIX_PLANE | S3C_WINCONx_ALPHA_SEL_1;
            s3cfb_fimd.wincon2 = S3C_WINCONx_HAWSWP_ENABLE | S3C_WINCONx_BURSTLEN_16WORD | S3C_WINCONx_BPPMODE_F_16BPP_565 | S3C_WINCONx_BLD_PIX_PLANE | S3C_WINCONx_ALPHA_SEL_1;
            s3cfb_fimd.wincon3 = S3C_WINCONx_HAWSWP_ENABLE | S3C_WINCONx_BURSTLEN_16WORD | S3C_WINCONx_BPPMODE_F_16BPP_565 | S3C_WINCONx_BLD_PIX_PLANE | S3C_WINCONx_ALPHA_SEL_1;
            s3cfb_fimd.wincon4 = S3C_WINCONx_HAWSWP_ENABLE | S3C_WINCONx_BURSTLEN_16WORD | S3C_WINCONx_BPPMODE_F_16BPP_565 | S3C_WINCONx_BLD_PIX_PLANE | S3C_WINCONx_ALPHA_SEL_1;
            s3cfb_fimd.bpp = S3CFB_PIXEL_BPP_16;
            s3cfb_fimd.bytes_per_pixel = 2;
            break;
    }
    //配置为窗口0,1,2,3,4为rgb565模式,dma直传,burst mode, BURSTLEN=16Word
    writel(s3cfb_fimd.wincon0, S3C_WINCON0); //0x10014
    writel(s3cfb_fimd.wincon1, S3C_WINCON1); //0x10016
    writel(s3cfb_fimd.wincon2, S3C_WINCON2); //0x10016
    writel(s3cfb_fimd.wincon3, S3C_WINCON3); //0x10016
    writel(s3cfb_fimd.wincon4, S3C_WINCON4); //0x10016
    writel(s3cfb_fimd.wpalcon, S3C_WPALCON); //0x00006
    //启动video output
    writel(s3cfb_fimd.wincon0 | S3C_WINCONx_ENWIN_F_ENABLE, S3C_WINCON0);   //0x10014
    //设置clock并启动video output
    writel(s3cfb_fimd.vidcon0 | S3C_VIDCON0_ENVID_ENABLE | S3C_VIDCON0_ENVID_F_ENABLE, S3C_VIDCON0); //0x350
}

三. 中断及数据传输
3.1 中断过程

irqreturn_t s3cfb_irq(int irqno, void *param)
{
    writel(readl(S3C_VIDINTCON1), S3C_VIDINTCON1);    //清中断

    s3cfb_fimd.vsync_info.count++;
    wake_up_interruptible(&s3cfb_fimd.vsync_info.wait_queue);  //唤醒工作队列
    return IRQ_HANDLED;
}

这个地方正在等侍工作队列,收到唤醒信号之后,就返回

int s3cfb_wait_for_vsync(void)
{
    cnt = s3cfb_fimd.vsync_info.count;
    wait_event_interruptible_timeout(s3cfb_fimd.vsync_info.wait_queue, cnt != s3cfb_fimd.vsync_info.count, HZ / 10);
    return cnt;
}

 

int s3cfb_ioctl(struct fb_info *info, unsigned int cmd, unsigned long arg)
{
    switch(cmd){
    case FBIO_WAITFORVSYNC:
        if (get_user(crt, (unsigned int __user *)arg))
            return -EFAULT;

        return s3cfb_wait_for_vsync();
    }
}

附录:
1. local_irq_save
s3cfb_probe
--> s3cfb_init_registers
    --> local_irq_save
2. 关于DMA
s3cfb_probe
--> s3cfb_map_video_memory
    --> dma_alloc_writecombine
    --> __dma_alloc