/*FrameBuffer設(shè)備名稱*/
static char driver_name[] = "my2440_lcd";

/*定義一個(gè)結(jié)構(gòu)體用來(lái)維護(hù)驅(qū)動(dòng)程序中各函數(shù)中用到的變量
  先別看結(jié)構(gòu)體要定義這些成員，到各函數(shù)使用的地方就明白了*/
struct my2440fb_var
{
    int lcd_irq_no;           /*保存LCD中斷號(hào)*/
    struct clk *lcd_clock;    /*保存從平臺(tái)時(shí)鐘隊(duì)列中獲取的LCD時(shí)鐘*/
    struct resource *lcd_mem; /*LCD的IO空間*/
    void __iomem *lcd_base;   /*LCD的IO空間映射到虛擬地址*/
    struct device *dev;

    struct s3c2410fb_hw regs; /*表示5個(gè)LCD配置寄存器，s3c2410fb_hw定義在mach-s3c2410/include/mach/fb.h中*/

    /*定義一個(gè)數(shù)組來(lái)充當(dāng)調(diào)色板。
    據(jù)數(shù)據(jù)手冊(cè)描述，TFT屏色位模式為8BPP時(shí)，調(diào)色板(顏色表)的長(zhǎng)度為256，調(diào)色板起始地址為0x4D000400*/
    u32    palette_buffer[256]; 

    u32 pseudo_pal[16];   
    unsigned int palette_ready; /*標(biāo)識(shí)調(diào)色板是否準(zhǔn)備好了*/
};

/*用做清空調(diào)色板(顏色表)*/
#define PALETTE_BUFF_CLEAR (0x80000000)    

/*LCD平臺(tái)驅(qū)動(dòng)結(jié)構(gòu)體，平臺(tái)驅(qū)動(dòng)結(jié)構(gòu)體定義在platform_device.h中，該結(jié)構(gòu)體成員接口函數(shù)在第②步中實(shí)現(xiàn)*/
static struct platform_driver lcd_fb_driver =
{
    .probe     = lcd_fb_probe,               /*FrameBuffer設(shè)備探測(cè)*/
    .remove    = __devexit_p(lcd_fb_remove), /*FrameBuffer設(shè)備移除*/
    .suspend   = lcd_fb_suspend,             /*FrameBuffer設(shè)備掛起*/
    .resume    = lcd_fb_resume,              /*FrameBuffer設(shè)備恢復(fù)*/
    .driver    =
    {
        /*注意這里的名稱一定要和系統(tǒng)中定義平臺(tái)設(shè)備的地方一致，這樣才能把平臺(tái)設(shè)備與該平臺(tái)設(shè)備的驅(qū)動(dòng)關(guān)聯(lián)起來(lái)*/
        .name = "s3c2410-lcd",
        .owner = THIS_MODULE,
    },
};

static int __init lcd_init(void)
{
    /*在Linux中，幀緩沖設(shè)備被看做是平臺(tái)設(shè)備，所以這里注冊(cè)平臺(tái)設(shè)備*/
    return platform_driver_register(&lcd_fb_driver);
}

static void __exit lcd_exit(void)
{
    /*注銷平臺(tái)設(shè)備*/
    platform_driver_unregister(&lcd_fb_driver);
}

module_init(lcd_init);
module_exit(lcd_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Huang Gang");
MODULE_DESCRIPTION("My2440 LCD FrameBuffer Driver");

    for (i = 0; i < mach_info->num_displays; i++) /*fb緩存的長(zhǎng)度*/
    {
        /*計(jì)算FrameBuffer緩存的最大大小，這里右移3位(即除以8)是因?yàn)樯荒Ｊ紹PP是以位為單位*/
        unsigned long smem_len = (mach_info->displays[i].xres * mach_info->displays[i].yres * mach_info->displays[i].bpp) >> 3;

        if(fbinfo->fix.smem_len < smem_len)
        {
            fbinfo->fix.smem_len = smem_len;
        }
    }

    /*初始化LCD控制器之前要延遲一段時(shí)間*/
    msleep(1);

    /*初始化完fb_info后，開(kāi)始對(duì)LCD各寄存器進(jìn)行初始化，其定義在后面講到*/
    my2440fb_init_registers(fbinfo);

    /*初始化完寄存器后，開(kāi)始檢查fb_info中的可變參數(shù)，其定義在后面講到*/
    my2440fb_check_var(fbinfo);
    
    /*申請(qǐng)幀緩沖設(shè)備fb_info的顯示緩沖區(qū)空間，其定義在后面講到*/
    ret = my2440fb_map_video_memory(fbinfo);
    if (ret)
    {
        dev_err(&pdev->dev, "failed to allocate video RAM: %d\n", ret);
        ret = -ENOMEM;
        goto err_nofb;
    }

    /*最后，注冊(cè)這個(gè)幀緩沖設(shè)備fb_info到系統(tǒng)中, register_framebuffer定義在fb.h中在fbmem.c中實(shí)現(xiàn)*/
    ret = register_framebuffer(fbinfo);
    if (ret < 0)
    {
        dev_err(&pdev->dev, "failed to register framebuffer device: %d\n", ret);
        goto err_video_nomem;
    }

    /*對(duì)設(shè)備文件系統(tǒng)的支持(對(duì)設(shè)備文件系統(tǒng)的理解請(qǐng)參閱：嵌入式Linux之我行——設(shè)備文件系統(tǒng)剖析與使用)
     創(chuàng)建frambuffer設(shè)備文件，device_create_file定義在linux/device.h中*/
    ret = device_create_file(&pdev->dev, &dev_attr_debug);
    if (ret)
    {
        dev_err(&pdev->dev, "failed to add debug attribute\n");
    }

    return 0;

/*以下是上面錯(cuò)誤處理的跳轉(zhuǎn)點(diǎn)*/
err_nomem:
    release_resource(fbvar->lcd_mem);
    kfree(fbvar->lcd_mem);

err_nomap:
    iounmap(fbvar->lcd_base);

err_noclk:
    clk_disable(fbvar->lcd_clock);
    clk_put(fbvar->lcd_clock);

err_noirq:
    free_irq(fbvar->lcd_irq_no, fbvar);

err_nofb:
    platform_set_drvdata(pdev, NULL);
    framebuffer_release(fbinfo);

err_video_nomem:
    my2440fb_unmap_video_memory(fbinfo);

    return ret;
}

/*LCD中斷服務(wù)程序*/
static irqreturn_t lcd_fb_irq(int irq, void *dev_id)
{
    struct my2440fb_var    *fbvar = dev_id;
    void __iomem *lcd_irq_base;
    unsigned long lcdirq;

    /*LCD中斷掛起寄存器基地址*/
    lcd_irq_base = fbvar->lcd_base + S3C2410_LCDINTBASE;

    /*讀取LCD中斷掛起寄存器的值*/
    lcdirq = readl(lcd_irq_base + S3C24XX_LCDINTPND);

    /*判斷是否為中斷掛起狀態(tài)*/
    if(lcdirq & S3C2410_LCDINT_FRSYNC)
    {
        /*填充調(diào)色板*/
        if (fbvar->palette_ready)
        {
            my2440fb_write_palette(fbvar);
        }

        /*設(shè)置幀已插入中斷請(qǐng)求*/
        writel(S3C2410_LCDINT_FRSYNC, lcd_irq_base + S3C24XX_LCDINTPND);
        writel(S3C2410_LCDINT_FRSYNC, lcd_irq_base + S3C24XX_LCDSRCPND);
    }

    return IRQ_HANDLED;
}

/*填充調(diào)色板*/
static void my2440fb_write_palette(struct my2440fb_var *fbvar)
{
    unsigned int i;
    void __iomem *regs = fbvar->lcd_base;

    fbvar->palette_ready = 0;

    for (i = 0; i < 256; i++)
    {
        unsigned long ent = fbvar->palette_buffer[i];

        if (ent == PALETTE_BUFF_CLEAR)
        {
            continue;
        }

        writel(ent, regs + S3C2410_TFTPAL(i));

        if (readw(regs + S3C2410_TFTPAL(i)) == ent)
        {
            fbvar->palette_buffer[i] = PALETTE_BUFF_CLEAR;
        }
        else
        {
            fbvar->palette_ready = 1;
        }
    }
}

/*LCD各寄存器進(jìn)行初始化*/
static int my2440fb_init_registers(struct fb_info *fbinfo)
{
    unsigned long flags;
    void __iomem *tpal;
    void __iomem *lpcsel;

    /*從lcd_fb_probe探測(cè)函數(shù)設(shè)置的私有變量結(jié)構(gòu)體中再獲得LCD相關(guān)信息的數(shù)據(jù)*/
    struct my2440fb_var    *fbvar = fbinfo->par;
    struct s3c2410fb_mach_info *mach_info = fbvar->dev->platform_data;

    /*獲得臨時(shí)調(diào)色板寄存器基地址，S3C2410_TPAL宏定義在mach-s3c2410/include/mach/regs-lcd.h中。
    注意對(duì)于lpcsel這是一個(gè)針對(duì)三星TFT屏的一個(gè)專用寄存器，如果用的不是三星的TFT屏應(yīng)該不用管它。*/
    tpal = fbvar->lcd_base + S3C2410_TPAL;
    lpcsel = fbvar->lcd_base + S3C2410_LPCSEL;

    /*在修改下面寄存器值之前先屏蔽中斷，將中斷狀態(tài)保存到flags中*/
    local_irq_save(flags);

    /*這里就是在上一篇章中講到的把IO端口C和D配置成LCD模式*/
    modify_gpio(S3C2410_GPCUP, mach_info->gpcup, mach_info->gpcup_mask);
    modify_gpio(S3C2410_GPCCON, mach_info->gpccon, mach_info->gpccon_mask);
    modify_gpio(S3C2410_GPDUP, mach_info->gpdup, mach_info->gpdup_mask);
    modify_gpio(S3C2410_GPDCON, mach_info->gpdcon, mach_info->gpdcon_mask);

    /*恢復(fù)被屏蔽的中斷*/
    local_irq_restore(flags);

    writel(0x00, tpal);/*臨時(shí)調(diào)色板寄存器使能禁止*/
    writel(mach_info->lpcsel, lpcsel);/*在上一篇中講到過(guò)，它是三星TFT屏的一個(gè)寄存器，這里可以不管*/

    return 0;
}

/*該函數(shù)實(shí)現(xiàn)修改GPIO端口的值，注意第三個(gè)參數(shù)mask的作用是將要設(shè)置的寄存器值先清零*/
static inline void modify_gpio(void __iomem *reg, unsigned long set, unsigned long mask)
{
    unsigned long tmp;

    tmp = readl(reg) & ~mask;
    writel(tmp | set, reg);
}

/*檢查fb_info中的可變參數(shù)*/
static int my2440fb_check_var(struct fb_info *fbinfo)
{
    unsigned i;

    /*從lcd_fb_probe探測(cè)函數(shù)設(shè)置的平臺(tái)數(shù)據(jù)中再獲得LCD相關(guān)信息的數(shù)據(jù)*/
    struct fb_var_screeninfo *var = &fbinfo->var;/*fb_info中的可變參數(shù)*/
    struct my2440fb_var    *fbvar = fbinfo->par;/*在lcd_fb_probe探測(cè)函數(shù)中設(shè)置的私有結(jié)構(gòu)體數(shù)據(jù)*/
    struct s3c2410fb_mach_info *mach_info = fbvar->dev->platform_data;/*LCD的配置結(jié)構(gòu)體數(shù)據(jù)，這個(gè)配置結(jié)構(gòu)體的賦值在上一篇章的"3. 幀緩沖設(shè)備作為平臺(tái)設(shè)備"中*/

    struct s3c2410fb_display *display = NULL;
    struct s3c2410fb_display *default_display = mach_info->displays + mach_info->default_display;
    int type = default_display->type;/*LCD的類型，看上一篇章的"3. 幀緩沖設(shè)備作為平臺(tái)設(shè)備"中的type賦值是TFT類型*/

    /*驗(yàn)證X/Y解析度*/
    if (var->yres == default_display->yres &&
        var->xres == default_display->xres &&
        var->bits_per_pixel == default_display->bpp)
    {
        display = default_display;
    }
    else
    {
        for (i = 0; i < mach_info->num_displays; i++)
        {
            if (type == mach_info->displays[i].type &&
             var->yres == mach_info->displays[i].yres &&
             var->xres == mach_info->displays[i].xres &&
             var->bits_per_pixel == mach_info->displays[i].bpp)
            {
                display = mach_info->displays + i;
                break;
            }
        }
    }

    if (!display)
    {
        return -EINVAL;
    }

    /*配置LCD配置寄存器1中的5-6位(配置成TFT類型)和配置LCD配置寄存器5*/
    fbvar->regs.lcdcon1 = display->type;
    fbvar->regs.lcdcon5 = display->lcdcon5;

    /* 設(shè)置屏幕的虛擬解析像素和高度寬度 */
    var->xres_virtual = display->xres;
    var->yres_virtual = display->yres;
    var->height = display->height;
    var->width = display->width;

    /* 設(shè)置時(shí)鐘像素，行、幀切換值，水平同步、垂直同步長(zhǎng)度值 */
    var->pixclock = display->pixclock;
    var->left_margin = display->left_margin;
    var->right_margin = display->right_margin;
    var->upper_margin = display->upper_margin;
    var->lower_margin = display->lower_margin;
    var->vsync_len = display->vsync_len;
    var->hsync_len = display->hsync_len;

    /*設(shè)置透明度*/
    var->transp.offset = 0;
    var->transp.length = 0;

    /*根據(jù)色位模式(BPP)來(lái)設(shè)置可變參數(shù)中R、G、B的顏色位域。對(duì)于這些參數(shù)值的設(shè)置請(qǐng)參考CPU數(shù)據(jù)
    手冊(cè)中"顯示緩沖區(qū)與顯示點(diǎn)對(duì)應(yīng)關(guān)系圖"，例如在上一篇章中我就畫(huà)出了8BPP和16BPP時(shí)的對(duì)應(yīng)關(guān)系圖*/
    switch (var->bits_per_pixel)
    {
        case 1:
        case 2:
        case 4:
            var->red.offset  = 0;
            var->red.length  = var->bits_per_pixel;
            var->green       = var->red;
            var->blue        = var->red;
            break;
        case 8:/* 8 bpp 332 */
            if (display->type != S3C2410_LCDCON1_TFT)
            {
                var->red.length     = 3;
                var->red.offset     = 5;
                var->green.length   = 3;
                var->green.offset   = 2;
                var->blue.length    = 2;
                var->blue.offset    = 0;
            }else{
                var->red.offset     = 0;
                var->red.length     = 8;
                var->green          = var->red;
                var->blue           = var->red;
            }
            break;
        case 12:/* 12 bpp 444 */
            var->red.length         = 4;
            var->red.offset         = 8;
            var->green.length       = 4;
            var->green.offset       = 4;
            var->blue.length        = 4;
            var->blue.offset        = 0;
            break;
        case 16:/* 16 bpp */
            if (display->lcdcon5 & S3C2410_LCDCON5_FRM565)
            {
                /* 565 format */
                var->red.offset      = 11;
                var->green.offset    = 5;
                var->blue.offset     = 0;
                var->red.length      = 5;
                var->green.length    = 6;
                var->blue.length     = 5;
            } else {
                /* 5551 format */
                var->red.offset      = 11;
                var->green.offset    = 6;
                var->blue.offset     = 1;
                var->red.length      = 5;
                var->green.length    = 5;
                var->blue.length     = 5;
            }
            break;
        case 32:/* 24 bpp 888 and 8 dummy */
            var->red.length        = 8;
            var->red.offset        = 16;
            var->green.length      = 8;
            var->green.offset      = 8;
            var->blue.length       = 8;
            var->blue.offset       = 0;
            break;
    }

    return 0;
}

/*申請(qǐng)幀緩沖設(shè)備fb_info的顯示緩沖區(qū)空間*/
static int __init my2440fb_map_video_memory(struct fb_info *fbinfo)
{
    dma_addr_t map_dma;/*用于保存DMA緩沖區(qū)總線地址*/
    struct my2440fb_var    *fbvar = fbinfo->par;/*獲得在lcd_fb_probe探測(cè)函數(shù)中設(shè)置的私有結(jié)構(gòu)體數(shù)據(jù)*/
    unsigned map_size = PAGE_ALIGN(fbinfo->fix.smem_len);/*獲得FrameBuffer緩存的大小, PAGE_ALIGN定義在mm.h中*/

    /*將分配的一個(gè)寫(xiě)合并DMA緩存區(qū)設(shè)置為L(zhǎng)CD屏幕的虛擬地址(對(duì)于DMA請(qǐng)參考DMA相關(guān)知識(shí))
    dma_alloc_writecombine定義在arch/arm/mm/dma-mapping.c中*/
    fbinfo->screen_base = dma_alloc_writecombine(fbvar->dev, map_size, &map_dma, GFP_KERNEL);

    if (fbinfo->screen_base)
    {
        /*設(shè)置這片DMA緩存區(qū)的內(nèi)容為空*/
        memset(fbinfo->screen_base, 0x00, map_size);

        /*將DMA緩沖區(qū)總線地址設(shè)成fb_info不可變參數(shù)中framebuffer緩存的開(kāi)始位置*/
        fbinfo->fix.smem_start = map_dma;
    }

    return fbinfo->screen_base ? 0 : -ENOMEM;
}

/*釋放幀緩沖設(shè)備fb_info的顯示緩沖區(qū)空間*/
static inline void my2440fb_unmap_video_memory(struct fb_info *fbinfo)
{
    struct my2440fb_var    *fbvar = fbinfo->par;
    unsigned map_size = PAGE_ALIGN(fbinfo->fix.smem_len);

    /*跟申請(qǐng)DMA的地方想對(duì)應(yīng)*/
    dma_free_writecombine(fbvar->dev, map_size, fbinfo->screen_base, fbinfo->fix.smem_start);
}


/*LCD FrameBuffer設(shè)備移除的實(shí)現(xiàn)，注意這里使用一個(gè)__devexit宏，和lcd_fb_probe接口函數(shù)相對(duì)應(yīng)。
  在Linux內(nèi)核中，使用了大量不同的宏來(lái)標(biāo)記具有不同作用的函數(shù)和數(shù)據(jù)結(jié)構(gòu)，這些宏在include/linux/init.h
  頭文件中定義，編譯器通過(guò)這些宏可以把代碼優(yōu)化放到合適的內(nèi)存位置，以減少內(nèi)存占用和提高內(nèi)核效率。
  __devinit、__devexit就是這些宏之一，在probe()和remove()函數(shù)中應(yīng)該使用__devinit和__devexit宏。
  又當(dāng)remove()函數(shù)使用了__devexit宏時(shí)，則在驅(qū)動(dòng)結(jié)構(gòu)體中一定要使用__devexit_p宏來(lái)引用remove()，
  所以在第①步中就用__devexit_p來(lái)引用lcd_fb_remove接口函數(shù)。*/
static int __devexit lcd_fb_remove(struct platform_device *pdev)
{
    struct fb_info *fbinfo = platform_get_drvdata(pdev);
    struct my2440fb_var    *fbvar = fbinfo->par;

    /*從系統(tǒng)中注銷幀緩沖設(shè)備*/
    unregister_framebuffer(fbinfo);

    /*停止LCD控制器的工作*/
    my2440fb_lcd_enable(fbvar, 0);

    /*延遲一段時(shí)間，因?yàn)橥Ｖ筁CD控制器需要一點(diǎn)時(shí)間 */
    msleep(1);

    /*釋放幀緩沖設(shè)備fb_info的顯示緩沖區(qū)空間*/
    my2440fb_unmap_video_memory(fbinfo);

    /*將LCD平臺(tái)數(shù)據(jù)清空和釋放fb_info空間資源*/
    platform_set_drvdata(pdev, NULL);
    framebuffer_release(fbinfo);

    /*釋放中斷資源*/
    free_irq(fbvar->lcd_irq_no, fbvar);

    /*釋放時(shí)鐘資源*/
    if (fbvar->lcd_clock)
    {
        clk_disable(fbvar->lcd_clock);
        clk_put(fbvar->lcd_clock);
        fbvar->lcd_clock = NULL;
    }

    /*釋放LCD IO空間映射的虛擬內(nèi)存空間*/
    iounmap(fbvar->lcd_base);

    /*釋放申請(qǐng)的LCD IO端口所占用的IO空間*/
    release_resource(fbvar->lcd_mem);
    kfree(fbvar->lcd_mem);

    return 0;
}

/*停止LCD控制器的工作*/
static void my2440fb_lcd_enable(struct my2440fb_var *fbvar, int enable)
{
    unsigned long flags;

    /*在修改下面寄存器值之前先屏蔽中斷，將中斷狀態(tài)保存到flags中*/
    local_irq_save(flags);

    if (enable)
    {
        fbvar->regs.lcdcon1 |= S3C2410_LCDCON1_ENVID;
    }
    else
    {
        fbvar->regs.lcdcon1 &= ~S3C2410_LCDCON1_ENVID;
    }

    writel(fbvar->regs.lcdcon1, fbvar->lcd_base + S3C2410_LCDCON1);

    /*恢復(fù)被屏蔽的中斷*/
    local_irq_restore(flags);
}

/*對(duì)LCD FrameBuffer平臺(tái)設(shè)備驅(qū)動(dòng)電源管理的支持,CONFIG_PM這個(gè)宏定義在內(nèi)核中*/
#ifdef CONFIG_PM
/*當(dāng)配置內(nèi)核時(shí)選上電源管理，則平臺(tái)設(shè)備的驅(qū)動(dòng)就支持掛起和恢復(fù)功能*/
static int lcd_fb_suspend(struct platform_device *pdev, pm_message_t state)
{
    /*掛起LCD設(shè)備，注意這里掛起LCD時(shí)并沒(méi)有保存LCD控制器的各種狀態(tài)，所以在恢復(fù)后LCD不會(huì)繼續(xù)顯示掛起前的內(nèi)容
     若要繼續(xù)顯示掛起前的內(nèi)容，則要在這里保存LCD控制器的各種狀態(tài)，這里就不講這個(gè)了，以后講到電源管理再講*/
    struct fb_info *fbinfo = platform_get_drvdata(pdev);
    struct my2440fb_var    *fbvar = fbinfo->par;

    /*停止LCD控制器的工作*/
    my2440fb_lcd_enable(fbvar, 0);

    msleep(1);

    /*停止時(shí)鐘*/
    clk_disable(fbvar->lcd_clock);

    return 0;
}

static int lcd_fb_resume(struct platform_device *pdev)
{
    /*恢復(fù)掛起的LCD設(shè)備*/
    struct fb_info *fbinfo = platform_get_drvdata(pdev);
    struct my2440fb_var    *fbvar = fbinfo->par;

    /*開(kāi)啟時(shí)鐘*/
    clk_enable(fbvar->lcd_clock);

    /*初始化LCD控制器之前要延遲一段時(shí)間*/
    msleep(1);

    /*恢復(fù)時(shí)重新初始化LCD各寄存器*/
    my2440fb_init_registers(fbinfo);

    /*重新激活fb_info中所有的參數(shù)配置，該函數(shù)定義在第③步中再講*/
    my2440fb_activate_var(fbinfo);

    /*正與掛起時(shí)講到的那樣，因?yàn)闆](méi)保存掛起時(shí)LCD控制器的各種狀態(tài)，
    所以恢復(fù)后就讓LCD顯示空白，該函數(shù)定義也在第③步中再講*/
    my2440fb_blank(FB_BLANK_UNBLANK, fbinfo);

    return 0;
}
#else
/*如果配置內(nèi)核時(shí)沒(méi)選上電源管理,則平臺(tái)設(shè)備的驅(qū)動(dòng)就不支持掛起和恢復(fù)功能,這兩個(gè)函數(shù)也就無(wú)需實(shí)現(xiàn)了*/
#define lcd_fb_suspend    NULL
#define lcd_fb_resume    NULL
#endif