通过acpi_device_hid 得到device的HID

用acpi_device_hid 可以的到device的hid，如下所示：
static int acpi_processor_get_info(struct acpi_device *device)
{
//这里的#define ACPI_PROCESSOR_OBJECT_HID	"LNXCPU"


	if (!strcmp(acpi_device_hid(device), ACPI_PROCESSOR_OBJECT_HID)) {
		/* Declared with "Processor" statement; match ProcessorID */
		status = acpi_evaluate_object(pr->handle, NULL, NULL, &buffer);
		if (ACPI_FAILURE(status)) {
			dev_err(&device->dev,
				"Failed to evaluate processor object (0x%x)\n",
				status);
			return -ENODEV;
		}

	} 
}
可见acpi_device_hid 是从device->pnp.ids这个list中拿到device的hid的

const char *acpi_device_hid(struct acpi_device *device)
{
	struct acpi_hardware_id *hid;

	if (list_empty(&device->pnp.ids))
		return dummy_hid;

	hid = list_first_entry(&device->pnp.ids, struct acpi_hardware_id, list);
	return hid->id;
}
而这个device->pnp.ids 是在acpi_init_device_object 中初始化
void acpi_init_device_object(struct acpi_device *device, acpi_handle handle,
			     int type, unsigned long long sta)
{
	INIT_LIST_HEAD(&device->pnp.ids);
//通过acpi_set_pnp_ids ->acpi_add_id 将hid添加到pnp.ids
	acpi_set_pnp_ids(handle, &device->pnp, type);

}
可以看到是将hid添加到id添加的pnp->ids
static void acpi_add_id(struct acpi_device_pnp *pnp, const char *dev_id)
{
	struct acpi_hardware_id *id;

	id = kmalloc(sizeof(*id), GFP_KERNEL);
	if (!id)
		return;

	id->id = kstrdup_const(dev_id, GFP_KERNEL);
	if (!id->id) {
		kfree(id);
		return;
	}

	list_add_tail(&id->list, &pnp->ids);
	pnp->type.hardware_id = 1;
}