(转)Tiny210v2( S5PV210 ) 平台下 FIMD 对应 的 framebuffer 驱动中，关于 video buffer 的理解

原文:http://www.arm9home.net/read.php?tid-25938.html

管理提醒： 本帖被 xoom 执行加亮操作(2012-12-13)

如之前所说，一直想知道显示数据都在哪个地方，通常的数据，比如 framebuffer 中的显示数据，和OpenGL 处理的数据有啥关系。
目前为止我还没有弄明白 OpenGL 这块，但是 framebuffer 这部分差不多了。这篇文章记录了 framebuffer 的显示数据相关内容。

1. 关于FIMD

    Tiny210v2 开发板属于 s5pv210 的一种，在这块开发板上，显示部分又被叫做 FIMD，我不知道FIMD是什么的缩写，但D应该和Display Controller有关系吧。
    FIMD 的主要功能就是获取显示数据，并将数据输出到显示屏。当然期间会对显示数据进行处理：

         
 

    FIMD一共支持5个layer，在SoC用户手册中，将layer成为window，源代码中也叫做window。

         
 

    FIMD可以通过AXI总线从内存或者Camera哪里获取到显示数据，并进行合成。

         
 
    
2. 内核配置 framebuffer

    通过 make menuconfig 可以配置 framebuffer 相关的内容。
    
         
 

    保存以后，在 .config 文件中可以找到相关配置内容。
    
        .config
        --------------------------------------------------
 
复制代码
  1.         CONFIG_FB_S3C_DEFAULT_WINDOW=2
  2.         CONFIG_FB_S3C_NR_BUFFERS=3
  3.         CONFIG_FB_S3C_NUM_OVLY_WIN=1
  4.         CONFIG_FB_S3C_NUM_BUF_OVLY_WIN=3


    同样也会在头文件中生成宏定义：

        include/generated/autoconf.h
        --------------------------------------------------
 
复制代码
  1.         #define CONFIG_FB_S3C_DEFAULT_WINDOW 2
  2.         #define CONFIG_FB_S3C_NR_BUFFERS 3
  3.         #define CONFIG_FB_S3C_NUM_OVLY_WIN 1
  4.         #define CONFIG_FB_S3C_NUM_BUF_OVLY_WIN 3

    
    CONFIG_FB_S3C_DEFAULT_WINDOW 是指 默认的 window， 0-4。
    CONFIG_FB_S3C_NR_BUFFERS 是指 window 的buffer数，3个就是 trebble-buffer，2个就是double-buffer。
    其中第一个是正在显示的数据，又叫onscreen，其他几个是后台描画的数据，又叫offscreen，通过 flip 操作可以将 onscreen 数据和offscreen 数据交换。
    CONFIG_FB_S3C_NUM_OVLY_WIN 是 OVERLAY window， 0-4。
    CONFIG_FB_S3C_NUM_BUF_OVLY_WIN 是指 OVERLAY window 的buffer数，和 CONFIG_FB_S3C_NR_BUFFERS 一个意思。
        
3. 显示数据buffer

    内核初始话过程中，为这些window 的 buffer 预留了一部分内存。
    具体看下面的代码：

    初始化函数会首先映射内存空间：
        
 
复制代码
  1.         MACHINE_START(MINI210, "MINI210")
  2.             /* Maintainer: Kukjin Kim <kgene.kim@samsung.com> */
  3.             .boot_params    = S5P_PA_SDRAM + 0x100,
  4.             .fixup            = mini210_fixup,
  5.             .init_irq        = s5pv210_init_irq,
  6.             .map_io            = mini210_map_io,
  7.             .init_machine    = mini210_machine_init,
  8.         #ifdef CONFIG_S5P_HIGH_RES_TIMERS
  9.             .timer            = &s5p_systimer,
  10.         #else
  11.             .timer            = &s5p_timer,
  12.         #endif
  13.         MACHINE_END

    
    在映射内存空间中，保留了一部分内存，保留的大小就和window 以及 buffer数有关系：
    大小是 800 x 480 x 2个window x 3个buffer x RGBA的4字节,这是给通常显示数据的，
    除此之外，还预留了 YUV 的数据区域，1280 x 720 x 3个buffer x Y的一个字节数据 + 1280 x 720 x 3个buffer x UV的一个字节数据。
    另外还有一个 4096 字节大小的 数据。

    这些数据我只理解了 RGBA 数据， YUV 的数据不知道是干啥的？ 难道是给 HDMI 输出用的？
        
        arch/arm/mach-sp5v210/Mach-mini210.c
        --------------------------------------------------
 
复制代码
  1.         /* Multimedia support */
  2.         #define LCD_WIDTH                800
  3.         #define LCD_HEIGHT                480
  4.         #define BYTES_PER_PIXEL            4
  5.         #define NUM_BUFFER_OVLY            (CONFIG_FB_S3C_NUM_OVLY_WIN * CONFIG_FB_S3C_NUM_BUF_OVLY_WIN)
  6.         #define NUM_BUFFER                (CONFIG_FB_S3C_NR_BUFFERS + NUM_BUFFER_OVLY)
  7.         #define PXL2FIMD(pixels)        ((pixels) * BYTES_PER_PIXEL * NUM_BUFFER)
  8.         #define S5PV210_VIDEO_SAMSUNG_MEMSIZE_FIMD        PXL2FIMD(LCD_WIDTH * LCD_HEIGHT)
  9.         
  10.         static struct s5p_media_device mini210_media_devs[] = {
  11.             ......,
  12.             {
  13.                 .id            = S5P_MDEV_FIMD,
  14.                 .name        = "fimd",
  15.                 .bank        = 1,
  16.                 .memsize    = S5PV210_VIDEO_SAMSUNG_MEMSIZE_FIMD,
  17.                 .paddr        = 0,
  18.             },
  19.             ......,
  20.         }
  21.         static void __init mini210_map_io(void)
  22.         {
  23.             ......
  24.             frame_size = lcd->width * lcd->height * BYTES_PER_PIXEL;
  25.             fimd_size = ALIGN(frame_size, PAGE_SIZE) * NUM_BUFFER;
  26.             if (frame_size > 0x200000) {
  27.                 fimd_size += ALIGN(frame_size, PAGE_SIZE) * 2;            // Not used
  28.             }
  29.             /* Reserve 0x003f6000 bytes for PVR YUV video, and 1 page */
  30.             fimd_size += ALIGN(1280*720, PAGE_SIZE) * 3;
  31.             fimd_size += ALIGN(1280*360, PAGE_SIZE) * 3 + PAGE_SIZE;
  32.             if (fimd_size != S5PV210_VIDEO_SAMSUNG_MEMSIZE_FIMD) {
  33.                 mini210_fixup_bootmem(S5P_MDEV_FIMD, fimd_size);
  34.             }
  35.             ......
  36.             s5p_reserve_bootmem(mini210_media_devs, ARRAY_SIZE(mini210_media_devs), S5P_RANGE_MFC);
  37.             ......
  38.         }


    这些内存是PAGE对齐的，对齐的部分参考下面的算法。
    PAGE_SIZE 大小是 4096。

        include/linux/Const.h
        --------------------------------------------------
 
复制代码
  1.         #ifdef __ASSEMBLY__
  2.         #define _AC(X,Y)    X
  3.         #define _AT(T,X)    X
  4.         #else
  5.         #define __AC(X,Y)    (X##Y)
  6.         #define _AC(X,Y)    __AC(X,Y)
  7.         #define _AT(T,X)    ((T)(X))
  8.         #endif

        
        arch/arm/include/asm/Page.h
        --------------------------------------------------
 
复制代码
  1.         #define PAGE_SHIFT        12
  2.         #define PAGE_SIZE        (_AC(1,UL) << PAGE_SHIFT)

        
        include/linux/Kernel.h
        --------------------------------------------------
 
复制代码
  1.         #define __ALIGN_KERNEL_MASK(x, mask)    (((x) + (mask)) & ~(mask))
  2.         #define __ALIGN_KERNEL(x, a)        __ALIGN_KERNEL_MASK(x, (typeof(x))(a) - 1)
  3.         #define ALIGN(x, a)        __ALIGN_KERNEL((x), (a))

        

4. 内核关于FIMD内存预留的相关debug log

    在内核的 boot log 中，我们可以找到关于内存预留的log：

        dmesg log :
        --------------------------------------------------
        [    0.000000] s5p: 13060 kbytes system memory reserved for fimd at 0x3c330000, 1-bank base(0x3c330000) 
        
        [    0.648804] fimd at 0x3c330000



5. 物理内存视图

    画了一个简单的物理内存布局图，可以看到 RGBA 部分的数据，其实一共给 2 个 window 预留了。

        |              |
        |--------------|
        |              |0x3CFF0000 -- 0x3CFF0FFF || ????
        |--------------|
        |              |0x3CF7F000 -- 0x3CFEFFFF ||
        |--------------|                         ||
        |              |0x3CF0E000 -- 0x3CF7EFFF || treble-buffer YUV( UV ) framebuffer : 1280 x 360 x 1 byte
        |--------------|                         ||
        |              |0x3CE9D000 -- 0x3CF0DFFF ||
        |--------------|                           
        |              |0x3CDBC000 -- 0x3CE9EFFF ||
        |--------------|                         ||
        |              |0x3CCDB000 -- 0x3CDBBFFF || treble-buffer YUV(  Y ) framebuffer : 1280 x 720 x 1 byte
        |--------------|                         ||
        |              |0x3CBFA000 -- 0x3CCDAFFF ||
        |--------------|                           
        |              |0x3CA83000 -- 0x3CBF9FFF ||
        |--------------|                         ||
        |              |0x3C90C000 -- 0x3CA82FFF || treble-buffer RGBA framebuffer : 800 x 480 x 4 bytes
        |--------------|                         ||
        |              |0x3C795000 -- 0x3C90BFFF ||
        |--------------|                           
        |              |0x3C61E000 -- 0x3C794FFF ||
        |--------------|                         ||
        |              |0x3C4A7000 -- 0x3C61DFFF || treble-buffer RGBA framebuffer : 800 x 480 x 4 byte
        |--------------|                         ||
        |              |0x3C330000 -- 0x3C4A6FFF ||
        |--------------|
        |              |

6. 将预留的物理内存记录到platform信息中

    这些预留的物理内存，在 platform 初始化过程中，会映射到内存空间。
    在开发板初始化过程中，会进行 machine init, 而 machine init 过程中会调用 s3c_fb_set_platdata 初始化 platform 信息。
        
        arch/arm/mach-sp5v210/Mach-mini210.c
        --------------------------------------------------
 
复制代码
  1.         static struct s3c_platform_fb mini210_fb_data __initdata = {
  2.             .hw_ver            = 0x62,
  3.             .clk_name       = "sclk_fimd",
  4.             .nr_wins        = 5,
  5.             .default_win    = CONFIG_FB_S3C_DEFAULT_WINDOW,
  6.             .swap            = FB_SWAP_WORD | FB_SWAP_HWORD,
  7.         
  8.             .cfg_gpio        = lcd_cfg_gpio,
  9.             .backlight_on    = lcd_backlight_on,
  10.             .backlight_onoff= lcd_backlight_off,
  11.             .reset_lcd        = lcd_reset_lcd,
  12.         };
  14.         static void __init mini210_machine_init(void)
  15.         {
  16.             ......
  17.         #ifdef CONFIG_FB_S3C_MINI210
  18.             {
  19.                 struct s3cfb_lcd *mlcd = mini210_get_lcd();
  20.                 if (!(mlcd->args & 0x0f)) {
  21.                     if (readl(S5PV210_GPF0_BASE + 0x184) & 0x10)
  22.                         mlcd->args |= (1 << 7);
  23.                 }
  24.                 mini210_fb_data.lcd = mlcd;
  25.                 s3c_fb_set_platdata(&mini210_fb_data);
  26.             }
  27.         #endif
  28.             ......
  29.         }
  30.         
  31.         MACHINE_START(MINI210, "MINI210")
  32.             /* Maintainer: Kukjin Kim <kgene.kim@samsung.com> */
  33.             .boot_params    = S5P_PA_SDRAM + 0x100,
  34.             .fixup            = mini210_fixup,
  35.             .init_irq        = s5pv210_init_irq,
  36.             .map_io            = mini210_map_io,
  37.             .init_machine    = mini210_machine_init,
  38.         #ifdef CONFIG_S5P_HIGH_RES_TIMERS
  39.             .timer            = &s5p_systimer,
  40.         #else
  41.             .timer            = &s5p_timer,
  42.         #endif
  43.         MACHINE_END

    
    在platform初始化过程中，就会通过 pmem_start 和 pmem_size 分别记录这5个window 的物理内存地址和大小。    
    注意的是 platform 初始化，相当于是记录系统都有哪些资源。而设备驱动初始化过程中，比如s3cfb这个fb驱动，则会来使用这些资源。

        arch/arm/plat-s5p/include/plat/Fb.h
        --------------------------------------------------
 
复制代码
  1.         struct s3c_platform_fb {
  2.             int            hw_ver;
  3.             char        clk_name[16];
  4.             int            nr_wins;
  5.             int            nr_buffers[5];
  6.             int            default_win;
  7.             int            swap;
  8.             phys_addr_t    pmem_start[5]; /* starting physical address of memory region */
  9.             size_t        pmem_size[5]; /* size of memory region */
  10.             void        *lcd;
  11.             void        (*cfg_gpio)(struct platform_device *dev);
  12.             int            (*backlight_on)(struct platform_device *dev);
  13.             int            (*backlight_onoff)(struct platform_device *dev, int onoff);
  14.             int            (*reset_lcd)(struct platform_device *dev);
  15.             int            (*clk_on)(struct platform_device *pdev, struct clk **s3cfb_clk);
  16.             int            (*clk_off)(struct platform_device *pdev, struct clk **clk);
  17.         };

        
        arch/arm/plat-samsung/Dev-fb.c
        --------------------------------------------------
 
复制代码
  1.        void __init s3c_fb_set_platdata(struct s3c_platform_fb *pd)
  2.         {
  3.             struct s3c_platform_fb *npd;
  4.             struct s3cfb_lcd *lcd;
  5.             phys_addr_t pmem_start;
  6.             int i, default_win, num_overlay_win;
  7.             int frame_size;
  8.         
  9.             if (!pd)
  10.                 pd = &default_fb_data;
  11.         
  12.             npd = kmemdup(pd, sizeof(struct s3c_platform_fb), GFP_KERNEL);
  13.             if (!npd) {
  14.                 printk(KERN_ERR "%s: no memory for platform data\n", __func__);
  15.         
  16.             } else {
  17.                 for (i = 0; i < npd->nr_wins && i < NR_BUFFERS; i++) {
  18.                     npd->nr_buffers?? = 1;
  19.                 }
  20.         
  21.                 default_win = npd->default_win;
  22.                 num_overlay_win = CONFIG_FB_S3C_NUM_OVLY_WIN;
  23.                 if (num_overlay_win >= default_win) {
  24.                     printk(KERN_WARNING "%s: NUM_OVLY_WIN should be less than default \
  25.                             window number. set to 0.\n", __func__);
  26.                     num_overlay_win = 0;
  27.                 }
  28.                 ......
  29.                 
  30.                 /* set starting physical address & size of memory region for
  31.                  * overlay window and default window */
  32.                 pmem_start = s5p_get_media_memory_bank(S5P_MDEV_FIMD, 1);
  33.                 printk("fimd at 0x%08x\n", pmem_start);
  34.         
  35.                 for (i = 0; i < num_overlay_win; i++) {
  36.                     *(npd->nr_buffers+i) = CONFIG_FB_S3C_NUM_BUF_OVLY_WIN;
  37.                     *(npd->pmem_start+i) = pmem_start;
  38.                     *(npd->pmem_size+i) = frame_size *   *(npd->nr_buffers+i);
  39.                     pmem_start += *(npd->pmem_size+i);
  40.                 }
  41.         
  42.                 npd->nr_buffers[default_win] = CONFIG_FB_S3C_NR_BUFFERS;
  43.                 npd->pmem_start[default_win] = pmem_start;
  44.                 npd->pmem_size[default_win] = frame_size * npd->nr_buffers[default_win];
  45.         
  46.         #if defined(CONFIG_MACH_MINI210)
  47.                 npd->pmem_size[default_win] += ALIGN(1280*720, PAGE_SIZE) * 3;
  48.                 npd->pmem_size[default_win] += ALIGN(1280*360, PAGE_SIZE) * 3 + PAGE_SIZE;
  49.         
  50.                 if (frame_size > 0x200000) {                                        // Not Used : frame_size < 0x200000
  51.                     pmem_start += npd->pmem_size[default_win];
  52.                     for (; i < npd->nr_wins; i++) {
  53.                         if (i != default_win) {
  54.                             npd->nr_buffers[i] = 2;
  55.                             npd->pmem_start[i] = pmem_start;
  56.                             npd->pmem_size[i] = frame_size * npd->nr_buffers[i];
  57.                             break;
  58.                         }
  59.                     }
  60.                 }
  61.         #endif
  62.         
  63.                 s3c_device_fb.dev.platform_data = npd;
  64.             }
  65.         }

    
    我们需要留意一下上面这段代码，    
    因为 num_overlay_win 是 CONFIG_FB_S3C_NUM_OVLY_WIN=1,所以 for 循环只执行了一次，那么 window 0 的物理内存地址初始化了。
    然后又手工为 default_win 也就是 CONFIG_FB_S3C_DEFAULT_WINDOW=2 进行了初始化。
    也就是说： window 0 和 window 2 在platform初始化中记录了数据buffer的物理内存地址。
    虽然是 for 循环做的，我认为这个for循环写得不好。


7. 在s3cfb初始化过程中,为window 关联这些内存

    在初始化过程中，会分配fb设备相关数据结构，并注册fb设备。

        drivers/video/samsung/s3cfb.c
        --------------------------------------------------
 
复制代码
  1.         static int __devinit s3cfb_probe(struct platform_device *pdev)
  2.         {
  3.             ......
  4.             if (s3cfb_alloc_framebuffer(fbdev)) {
  5.                 ret = -ENOMEM;
  6.                 goto err_alloc;
  7.             }
  8.         
  9.             if (s3cfb_register_framebuffer(fbdev)) {
  10.                 ret = -EINVAL;
  11.                 goto err_register;
  12.             }
  13.             ......
  14.         }


    但是我们发现，只有当 fb 设备对应的 window 是 default window ，也就是 window 2 的时候，
    才会将 window 2 对应的内存映射到内存空间。
    虽然预留的物理内存是 window 0 和 window 2 的，但这个时候 window 0 的物理内存是没有被映射的。

        drivers/video/samsung/s3cfb.c
        --------------------------------------------------
 
复制代码
  1.         static int s3cfb_alloc_framebuffer(struct s3cfb_global *ctrl)
  2.         {
  3.             ......
  4.             for (i = 0; i < pdata->nr_wins; i++) {
  5.                 ctrl->fb[i] = framebuffer_alloc(sizeof(*ctrl->fb), ctrl->dev);
  6.                 if (!ctrl->fb[i]) {
  7.                     dev_err(ctrl->dev, "not enough memory\n");
  8.                     ret = -ENOMEM;
  9.                     goto err_alloc_fb;
  10.                 }
  11.                 ......
  12.                 if (i == pdata->default_win) {
  13.                     if (s3cfb_map_video_memory(ctrl->fb[i])) {
  14.                         dev_err(ctrl->dev,
  15.                             "failed to map video memory "
  16.                             "for default window (%d)\n", i);
  17.                         ret = -ENOMEM;
  18.                         goto err_map_video_mem;
  19.                     }
  20.                 }
  21.             }
  22.             ......
  23.         }

    
    这是注册 fb 设备的地方，只要注册成功，/dev 目录下就会有一个 fb 文件。
    虽然只给 window 2 映射了显示数据的内存，但是 for 循环还是将所有的 window 都注册设备文件了。
    这就是为什么 /dev 目录下有 fb0 - fb4 5个fb设备。其实每一个 fb 设备对应一个 window。
    
    另外需要注意的是，第一个注册的 fb 是 fb0，然后依次 ++。
    下面的代码在注册的时候， 首先注册的是 default window 2，然后是 3, 4, 0, 1。
    也就是说 ：
    fb0 -> window 2
    fb1 -> window 3
    fb2 -> window 4
    fb3 -> window 0
    fb4 -> window 1

    另外还需要注意的是，如果你直接去 cat  /dev/fbX ，只有 fb0 是成功的，其他全部失败，
    因为到目前位置，只有 fb0 也就是 default window 2，映射了显示数据的内存。
        
        drivers/video/samsung/s3cfb.c
        --------------------------------------------------
 
复制代码
  1.         static int s3cfb_register_framebuffer(struct s3cfb_global *ctrl)
  2.         {
  3.             ......
  4.             k = 0;
  5.             for (i = pdata->default_win;
  6.                 i < pdata->nr_wins + pdata->default_win; i++) {
  7.                     j = i % pdata->nr_wins;
  8.                     ret = register_framebuffer(ctrl->fb[j]);
  9.                     if (ret) {
  10.                         dev_err(ctrl->dev, "failed to register "
  11.                                 "framebuffer device\n");
  12.                         ret = -EINVAL;
  13.                         goto err_register_fb;
  14.                     }
  15.                     pdata->fb_file_minor[ j ] = k;
  16.                     k++;
  17.                     
  18.                     #ifndef CONFIG_FRAMEBUFFER_CONSOLE
  19.                     if (j == pdata->default_win) {
  20.                         s3cfb_check_var(&ctrl->fb[j]->var, ctrl->fb[j]);
  21.                         s3cfb_set_par(ctrl->fb[j]);
  22.                         s3cfb_draw_logo(ctrl->fb[j]);
  23.                     }
  24.                     #endif
  25.             }
  26.             ......
  27.         }


8. 内核关于显示内存映射的相关debug log

    需要注意一下，部分log中写的是fb2，但这个log是boot阶段的，真正有效的是fb0，
    代码中log写错了，fb 很多应该是 window。fb0 -> window 2

        dmesg log :
        --------------------------------------------------
        [  507.316250] [s3cfb]win 2: pmem_start=0x3c795000
        [  507.316292] [s3cfb][fb2] dma: 0x3c795000, cpu: 0xe1000000, size: 0x0085c000
        
        [  507.333888] PA FB = 0x3C795000, bits per pixel = 32
        [  507.333933] screen width=800 height=480 va=0xdc795000 pa=0x3c795000
        [  507.333987] xres_virtual = 800, yres_virtual = 1440, xoffset = 0, yoffset = 0
        [  507.336543] fb_size=8765440 
        [  507.339351] Back frameBuffer[0].VAddr=dc90c000 PAddr=3c90c000 size=1536000 
        [  507.346146] Back frameBuffer[1].VAddr=dca83000 PAddr=3ca83000 size=1536000 
        [  507.353014] Video Y Buffer[0].VAddr=dcbfa000 PAddr=3cbfa000 size=921600
        [  507.359576] Video Y Buffer[1].VAddr=dccdb000 PAddr=3ccdb000 size=921600 
        [  507.366161] Video Y Buffer[2].VAddr=dcdbc000 PAddr=3cdbc000 size=921600
        [  507.372750] Video UV Buffer[0].VAddr=dce9d000 PAddr=3ce9d000 size=462848
        [  507.379418] Video UV Buffer[1].VAddr=dcf0e000 PAddr=3cf0e000 size=462848
        [  507.386093] Video UV Buffer[2].VAddr=dcf7f000 PAddr=3cf7f000 size=462848


9. 显示数据使用内存映射的一些细节

    s3cfb_map_video_memory 这个函数用于映射显示数据的内存地址，
    如果是 platform 初始化过程中预留过物理内存，则会使用这个物理内存。
    否则就会临时申请一块内存。

    也就是说 window 0 和 window 2 会使用预留的物理内存。
    window 1 / window 3 / window 4 会使用新申请的内存。

        drivers/video/samsung/s3cfb.c
        --------------------------------------------------
 
复制代码
  1.         static int s3cfb_map_video_memory(struct fb_info *fb)
  2.         {
  3.             ......
  4.             if (win->owner == DMA_MEM_OTHER) {
  5.                 fix->smem_start = win->other_mem_addr;
  6.                 fix->smem_len = win->other_mem_size;
  7.                 return 0;
  8.             }
  9.         
  10.             if (fb->screen_base)
  11.                 return 0;
  12.         
  13.             if (pdata && pdata->pmem_start[win->id] && (pdata->pmem_size[win->id] >= fix->smem_len)) {
  14.                 fix->smem_start = pdata->pmem_start[win->id];
  15.                 fix->smem_len = pdata->pmem_size[win->id];
  16.                 fb->screen_base = ioremap_wc(fix->smem_start, pdata->pmem_size[win->id]);
  17.         
  18.                 dev_err(fbdev->dev, "[fb%d][win%d]: pmem_start=0x%x\n",
  19.                         pdata->fb_file_minor[win->id],win->id, pdata->pmem_start[win->id]);
  20.             } else {
  21.                 fb->screen_base = dma_alloc_writecombine(fbdev->dev,
  22.                         PAGE_ALIGN(fix->smem_len),
  23.                         (unsigned int *)&fix->smem_start, GFP_KERNEL);
  24.             }
  25.             ......
  26.         }


    除了在初始化的时候会映射以外，
    还可一通过 ioctl 来调用 s3cfb_map_video_memory。
    传递的参数是 FBIOPUT_VSCREENINFO。

        drivers/video/samsung/s3cfb.c
        --------------------------------------------------
 
复制代码
  1.         static int s3cfb_set_par(struct fb_info *fb)
  2.         {
  3.             ......
  4.             if (win->id != pdata->default_win) {
  5.                 fb->fix.line_length = fb->var.xres_virtual *
  6.                                 fb->var.bits_per_pixel / 8;
  7.                 fb->fix.smem_len = fb->fix.line_length * fb->var.yres_virtual;
  8.         
  9.                 s3cfb_map_video_memory(fb);
  10.             }
  11.             ......
  12.         }
  14.         struct fb_ops s3cfb_ops = {
  15.             .fb_set_par = s3cfb_set_par,
  16.         };
  18.         drivers/video/fbmem.c
  19.         --------------------------------------------------
  20.         int fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var)
  21.         {
  22.             ......
  23.             if (info->fbops->fb_set_par) {
  24.                 ret = info->fbops->fb_set_par(info);
  25.                 ......
  26.             }
  27.             ......
  28.         }
  30.         static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,unsigned long arg)
  31.         {
  32.             case FBIOPUT_VSCREENINFO:
  33.                 ......
  34.                 ret = fb_set_var(info, &var);
  35.                 .....
  36.                 break;
  37.         }
  39.         static long fb_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  40.         {
  41.             ......
  42.             return do_fb_ioctl(info, cmd, arg);
  43.             ......
  44.         }
  46.         static const struct file_operations fb_fops = {
  47.             ......
  48.             .unlocked_ioctl = fb_ioctl,
  49.             ......
  50.         };



10. 在s3cfb初始化过程中映射FIMD的控制寄存器，用于控制硬件

    FIMD的控制寄存器和内存是统一编址的，因此可以像使用内存一样访问他们，但前提是需要将他们映射到内存空间。
    内核代码中的寄存器地址定义都能和 SoC 用户手册对应上，我们看看下面的截图，很一致吧。
    但是在看代码的过程中，我发现代码使用的寄存器的一些信息，Soc 用户手册没有，是不是用户手册比较老了？
    
         
 

         
 

    在 s3cfb 模块初始化的过程中，就会将控制寄存器映射到内存中。

        arch/arm/mach-sp5v210/include/mach/map.h
        --------------------------------------------------
 
复制代码
  1.         #define S5PV210_PA_LCD          (0xF8000000)
  2.         #define S5P_PA_LCD              S5PV210_PA_LCD
  3.         #define S5PV210_SZ_LCD          SZ_1M
  4.         #define S5P_SZ_LCD              S5PV210_SZ_LCD

        
        
        arch/arm/plat-samsung/dev-fb.c
        --------------------------------------------------
 
复制代码
  1.         static struct resource s3cfb_resource[] = {
  2.             [0] = {
  3.                 .start        = S5P_PA_LCD,
  4.                 .end        = S5P_PA_LCD + S5P_SZ_LCD - 1,
  5.                 .flags        = IORESOURCE_MEM,
  6.             },
  7.             [1] = {
  8.                 .start        = IRQ_LCD1,
  9.                 .end        = IRQ_LCD1,
  10.                 .flags        = IORESOURCE_IRQ,
  11.             },
  12.             [2] = {
  13.                 .start        = IRQ_LCD0,
  14.                 .end        = IRQ_LCD0,
  15.                 .flags        = IORESOURCE_IRQ,
  16.             },
  17.         };
  18.         
  19.         static u64 fb_dma_mask = 0xffffffffUL;
  20.         
  21.         struct platform_device s3c_device_fb = {
  22.             .name            = "s3cfb",
  23.             .id                = -1,
  24.             .num_resources    = ARRAY_SIZE(s3cfb_resource),
  25.             .resource        = s3cfb_resource,
  26.             .dev            = {
  27.                 .dma_mask            = &fb_dma_mask,
  28.                 .coherent_dma_mask    = 0xffffffffUL
  29.             }
  30.         };
  31.         
  32.         drivers/video/samsung/s3cfb.c
  33.         --------------------------------------------------
  34.         static int __devinit s3cfb_probe(struct platform_device *pdev)
  35.         {
  36.             ......
  37.             res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  38.             if (!res) {
  39.                 dev_err(fbdev->dev, "failed to get io memory region\n");
  40.                 ret = -EINVAL;
  41.                 goto err_io;
  42.             }
  43.         
  44.             res = request_mem_region(res->start, res->end - res->start + 1, pdev->name);
  45.             if (!res) {
  46.                 dev_err(fbdev->dev, "failed to request io memory region\n");
  47.                 ret = -EINVAL;
  48.                 goto err_io;
  49.             }
  50.         
  51.             fbdev->regs = ioremap(res->start, res->end - res->start + 1);
  52.             if (!fbdev->regs) {
  53.                 dev_err(fbdev->dev, "failed to remap io region\n");
  54.                 ret = -EINVAL;
  55.                 goto err_mem;
  56.             }
  57.             ......
  58.         }

        
    s3cfb_fimd6x.c这个文件将读写 FIMD 的控制寄存器相关功能都集中在这里了。
    我理解 6x 可能是对应硬件版本号，因为印象中看到硬件版本号好象是 0x62。

    通过设定这些控制寄存器，就能控制比如 window 是否显示啊，显示数据格式是啥啊，显示数据地址在哪里啊，等等。

        drivers/video/samsung/s3cfb_fimd6x.c
        --------------------------------------------------
 
复制代码
  1.         int s3cfb_display_on(struct s3cfb_global *ctrl)
  2.         {
  3.             u32 cfg;
  4.         
  5.             cfg = readl(ctrl->regs + S3C_VIDCON0);
  6.             cfg |= (S3C_VIDCON0_ENVID_ENABLE | S3C_VIDCON0_ENVID_F_ENABLE);
  7.             writel(cfg, ctrl->regs + S3C_VIDCON0);
  8.         
  9.             dev_dbg(ctrl->dev, "global display is on\n");
  10.         
  11.             return 0;
  12.         }



11. 用户空间的测试用例

    这个用例其实是用来确认 /dev 目录下的 fb0 - fb4 是否好用的，以及 window 之间的alpha透过是否正确。

    关于 window 之间的层次关系可以参考：
         
 

    下面的代码，大概意思是：
    * 打开 window 0 - window 4 对应的 fb 设备文件。
    * 设置这些 window 都是 800 x 480 x RGBA
    * 设置这些 window 内部的显示数据，是从 window 0 - window 4 开始的，分别画 500x480, 400x480, 300x480, 200x480, 100x480 这么大块数据。
    * 让window 的显示数据显示出来。

        s3cfb_test.c
        --------------------------------------------------
 
复制代码
  1.         #include <sys/types.h>
  2.         #include <sys/stat.h>
  3.         #include <sys/ioctl.h>
  4.         #include <sys/mman.h>
  5.         #include <fcntl.h>
  6.         #include <stdio.h>
  7.         #include <string.h>
  8.         #include <linux/fb.h>
  9.         
  10.         
  11.         #define    WIN0    0
  12.         #define    WIN1    1
  13.         #define    WIN2    2
  14.         #define    WIN3    3
  15.         #define    WIN4    4
  16.         #define    WIN_MAX    5
  17.         
  18.         const char * fb_file_path[ WIN_MAX ] = {
  19.         /* WIN0 */"/dev/fb3",
  20.         /* WIN1 */"/dev/fb4",
  21.         /* WIN2 */"/dev/fb0",
  22.         /* WIN3 */"/dev/fb1",
  23.         /* WIN4 */"/dev/fb2"
  24.         };
  25.         const int fb_x[ WIN_MAX ] = {
  26.         /* WIN0 */500,
  27.         /* WIN1 */400,
  28.         /* WIN2 */300,
  29.         /* WIN3 */200,
  30.         /* WIN4 */100
  31.         };
  32.         const int fb_color[ WIN_MAX ] = {
  33.         /* WIN0 */0x10FFFFFF,
  34.         /* WIN1 */0x10FF0000,
  35.         /* WIN2 */0x1000FF00,
  36.         /* WIN3 */0x100000FF,
  37.         /* WIN4 */0x10000000,
  38.         };
  39.         
  40.         void draw_framebuffer( int win, int fd, int xres, int yres )
  41.         {
  42.             int i, j;
  43.             int *p;
  44.             int color;
  45.             
  46.             p = mmap( NULL, xres*yres*4, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0 );
  47.             if( !p ){
  48.                 printf( "mmap failed\n" );
  49.                 return;
  50.             }
  51.         
  52.             /* draw default color with alpha : all pass through*/
  53.             for( j = 0; j < yres; j++ ){
  54.                 for( i = 0; i < xres ; i++ ){
  55.                     *( p + j * xres + i ) = 0x00FFFFFF;
  56.                 }
  57.             }
  58.         
  59.             /* draw color */
  60.             for( j = 0; j < yres; j++ ){
  61.                 for( i = 0; i < fb_x[win] ; i++ ){
  62.                     *( p + j * xres + i ) = fb_color[win];
  63.                 }
  64.             }
  65.         
  66.             munmap( p, xres*yres*4 );
  67.         }
  68.         
  69.         int main( int argc, char *argv[] )
  70.         {
  71.             int i;
  72.             int ret;
  73.             struct fb_var_screeninfo var;
  74.             int    blank;
  75.             int fd[ WIN_MAX ];
  76.         
  77.             /* initial */
  78.             memset( fd, -1, sizeof( fd ) );
  79.         
  80.             /* open framebuffer */
  81.             for( i=0; i<WIN_MAX; i++ ){
  82.                 fd[i] = open( fb_file_path[i], O_RDWR );
  83.                 if( fd[i] < 0 ){
  84.                     printf( "open %s failed\n", fb_file_path[i] );
  85.                     goto end;
  86.                 }
  87.             }
  88.             printf( "open framebuffer ok\n" );
  89.         
  90.             /* set screen info */
  91.             ret = ioctl( fd[WIN2], FBIOGET_VSCREENINFO, &var );
  92.             if( ret < 0 ){
  93.                 printf( "ioctl %s FBIOGET_VSCREENINFO failed\n", fb_file_path[WIN2] );
  94.                 goto end;
  95.             }
  96.         
  97.             var.activate = FB_ACTIVATE_FORCE;
  98.             var.yres_virtual = var.yres;
  99.             
  100.             for( i=0; i<WIN_MAX; i++ ){
  101.                 ret = ioctl( fd[i], FBIOPUT_VSCREENINFO, &var );
  102.                 if( ret < 0 ){
  103.                     printf( "ioctl %s FBIOPUT_VSCREENINFO failed\n", fb_file_path[i] );
  104.                     goto end;
  105.                 }
  106.             }
  107.             printf( "set screeninfo ok\n" );
  108.         
  109.             /* draw some color */
  110.             for( i=0; i<WIN_MAX; i++ ){
  111.                 draw_framebuffer( i, fd[i], var.xres, var.yres );
  112.             }
  113.             printf( "draw color ok\n" );
  114.         
  115.             /* show window */
  116.             blank = FB_BLANK_UNBLANK;
  117.         
  118.             for( i=0; i<WIN_MAX; i++ ){
  119.                 ret = ioctl( fd[i], FBIOBLANK, blank );
  120.                 if( ret < 0 ){
  121.                     printf( "ioctl %s FBIOBLANK failed\n", fb_file_path[i] );
  122.                     goto end;
  123.                 }
  124.             }
  125.             printf( "show window ok\n" );
  126.         
  127.             /* wait input */    
  128.             getchar();
  129.         end:
  130.             return 0;
  131.         }

        
    下面是屏幕截图，其实我对 RGB 不太了解，不知到什么值应该是什么颜色，但 只描画了红/绿/蓝 三种颜色，而屏幕上不是这三种颜色。
    说明 alpha blending 应该是正常工作了的。

         
 

END
posted @ 2013-09-04 17:55  @菜鸟爱学习@  阅读(766)  评论(0)  编辑  收藏  举报