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acpi_create_platform_device 这个函数会为没有platform_driver 自动创建platform_device设备。只有当用户只调用register_platform_driver就可以匹配device和driver其源码分析如下：struct platform_device *acpi_create_platform_device(struct acpi_device *adev,					struct property_entry *properties){	struct platform_device *pdev = NULL;	struct platform_device_info pdevinfo;	struct resource_entry *rentry;	struct list_head resource_list;	struct resource *resources = NULL;	int count;	/* If the ACPI node already has a physical device attached, skip it. */	#如果这个设备已经有一个物理节点attach了，则退出。简单说一个设备只能调用一次这个函数	if (adev->physical_node_count)		return NULL;	#保存在forbidden_id_list 中的设备是禁止加载的。如果遇到这种设备则退出	if (!acpi_match_device_ids(adev, forbidden_id_list))		return ERR_PTR(-EINVAL);	#初始化保存设备资源的链表	INIT_LIST_HEAD(&resource_list);	#获取这个device的资源，如果count小于零说明获取资源失败，则退出	count = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);	if (count < 0) {		return NULL;	} else if (count > 0) {		#根据count数来申请内存老保存资源		resources = kzalloc(count * sizeof(struct resource),				    GFP_KERNEL);		if (!resources) {			dev_err(&adev->dev, "No memory for resources\n");			acpi_dev_free_resource_list(&resource_list);			return ERR_PTR(-ENOMEM);		}		count = 0;		#将所有的资源保存在resource中		list_for_each_entry(rentry, &resource_list, node)			acpi_platform_fill_resource(adev, rentry->res,						    &resources[count++]);		acpi_dev_free_resource_list(&resource_list);	}	#清空pdevinfo 结构体	memset(&pdevinfo, 0, sizeof(pdevinfo));	/*	 * If the ACPI node has a parent and that parent has a physical device	 * attached to it, that physical device should be the parent of the	 * platform device we are about to create.	 */	 #给pdeinfo 赋值	pdevinfo.parent = adev->parent ?		acpi_get_first_physical_node(adev->parent) : NULL;	pdevinfo.name = dev_name(&adev->dev);	pdevinfo.id = -1;	pdevinfo.res = resources;	pdevinfo.num_res = count;	pdevinfo.fwnode = acpi_fwnode_handle(adev);	pdevinfo.properties = properties;	#检车这个device是否支持dma，如果支持的话，把dma mask设置为32bit	if (acpi_dma_supported(adev))		pdevinfo.dma_mask = DMA_BIT_MASK(32);	else		pdevinfo.dma_mask = 0;	#前面的准备工作结束后，调用下面这个函数把pdevinfo注册给kernel	#platform_device_register_full->platform_device_add->device_add 	pdev = platform_device_register_full(&pdevinfo);	if (IS_ERR(pdev))		dev_err(&adev->dev, "platform device creation failed: %ld\n",			PTR_ERR(pdev));	else {		set_dev_node(&pdev->dev, acpi_get_node(adev->handle));		dev_dbg(&adev->dev, "created platform device %s\n",			dev_name(&pdev->dev));	}	kfree(resources);	return pdev;}

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