3. FrameBuffer驱动框架：注册/注销流程、probe/remove回调、file_operations实现

// 典型probe回调示例
static int myfb_probe(struct platform_device *pdev)
{
    struct fb_info *info;
    struct myfb_par *par;
    int ret;

    // 1. 分配fb_info + 私有数据
    info = framebuffer_alloc(sizeof(struct myfb_par), &pdev->dev);
    if (!info)
        return -ENOMEM;

    par = info->par;
    // 2. 填充fb_ops
    info->fbops = &myfb_ops;
    // 3. 设置固定/可变参数
    strcpy(info->fix.id, "myfb");
    info->fix.smem_start = ...;  // 物理地址
    info->fix.smem_len = ...;    // 显存大小
    info->fix.line_length = ...; // 行字节数
    info->var.xres = 1024;
    info->var.yres = 600;
    info->var.bits_per_pixel = 32;
    // 4. 硬件初始化（寄存器映射、时钟使能等）
    par->regs = devm_platform_ioremap_resource(pdev, 0);
    if (IS_ERR(par->regs)) {
        ret = PTR_ERR(par->regs);
        goto err_free_info;
    }
    // 5. 注册FrameBuffer
    ret = register_framebuffer(info);
    if (ret < 0) {
        dev_err(&pdev->dev, "Failed to register framebuffer\n");
        goto err_free_info;
    }
    platform_set_drvdata(pdev, info);
    return 0;

err_free_info:
    framebuffer_release(info);
    return ret;
}

// 典型remove回调示例
static int myfb_remove(struct platform_device *pdev)
{
    struct fb_info *info = platform_get_drvdata(pdev);

    // 1. 注销FrameBuffer设备
    unregister_framebuffer(info);
    // 2. 硬件去初始化（示例）
    // iounmap(par->regs);
    // free_irq(...);
    // 3. 释放fb_info
    framebuffer_release(info);
    return 0;
}

// fb_mmap 典型实现
static int myfb_mmap(struct fb_info *info, struct vm_area_struct *vma)
{
    unsigned long start = vma->vm_start;
    unsigned long size = vma->vm_end - vma->vm_start;
    unsigned long pfn = info->fix.smem_start >> PAGE_SHIFT;

    // 设置映射属性：可读可写、非缓存（适合帧缓冲）
    vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
    // 禁止换出
    vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;

    // 建立页表映射
    if (remap_pfn_range(vma, start, pfn, size, vma->vm_page_prot))
        return -EAGAIN;

    return 0;
}

// fb_ioctl 核心命令处理片段
static int myfb_ioctl(struct fb_info *info, unsigned int cmd, unsigned long arg)
{
    struct myfb_par *par = info->par;

    switch (cmd) {
    case FBIOGET_VSCREENINFO: {
        if (copy_to_user((void __user *)arg, &info->var,
                         sizeof(info->var)))
            return -EFAULT;
        return 0;
    }
    case FBIOPUT_VSCREENINFO: {
        struct fb_var_screeninfo var;
        if (copy_from_user(&var, (void __user *)arg, sizeof(var)))
            return -EFAULT;
        // 验证参数合法性
        if (var.xres > 1920 || var.yres > 1080)
            return -EINVAL;
        // 更新info->var
        info->var = var;
        // 调用硬件配置函数
        myfb_set_par(info);
        return 0;
    }
    case FBIOBLANK: {
        int blank_mode = (int)arg;
        myfb_blank(blank_mode, info);
        return 0;
    }
    default:
        return -EINVAL;
    }
}

// 平台驱动定义
static struct platform_driver myfb_driver = {
    .probe  = myfb_probe,
    .remove = myfb_remove,
    .driver = {
        .name = "myfb",
        .of_match_table = myfb_of_match, // 设备树匹配表
    },
};

// 模块入口/出口
module_platform_driver(myfb_driver);

MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("Simple FrameBuffer Driver");
MODULE_LICENSE("GPL");