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acpi_bus_get_status这个函数获取acpi_device对应handle的_STA的值，然后将这个值赋值给acpi_device其使用的例程如下：	if (acpi_bus_get_status(battery->device)) {		ACPI_EXCEPTION((AE_INFO, AE_ERROR, "Evaluating _STA"));		return -ENODEV;	}其源码分析如下：int acpi_bus_get_status(struct acpi_device *device){	acpi_status status;	unsigned long long sta;	#如果这个设备已经不再了，则设置这个acpi_device的状态为ACPI_STA_DEFAULT后退出	if (acpi_device_always_present(device)) {		acpi_set_device_status(device, ACPI_STA_DEFAULT);		return 0;	}	/* Battery devices must have their deps met before calling _STA */	#对电池设备特殊对待	if (acpi_device_is_battery(device) && device->dep_unmet) {		acpi_set_device_status(device, 0);		return 0;	}	#获得acpi_device对应handle的sta的状态	status = acpi_bus_get_status_handle(device->handle, &sta);	if (ACPI_FAILURE(status))		return -ENODEV;	#将sta的值赋值给acpi_device	acpi_set_device_status(device, sta);	if (device->status.functional && !device->status.present) {		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device [%s] status [%08x]: "		       "functional but not present;\n",			device->pnp.bus_id, (u32)sta));	}	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device [%s] status [%08x]\n",			  device->pnp.bus_id, (u32)sta));	return 0;}我们看看如果通过handle 拿到sta的状态，原来就是直接获取bios提供的_STA 这个整形值acpi_status acpi_bus_get_status_handle(acpi_handle handle,				       unsigned long long *sta){	acpi_status status;	status = acpi_evaluate_integer(handle, "_STA", NULL, sta);	if (ACPI_SUCCESS(status))		return AE_OK;	if (status == AE_NOT_FOUND) {		*sta = ACPI_STA_DEVICE_PRESENT | ACPI_STA_DEVICE_ENABLED |		       ACPI_STA_DEVICE_UI      | ACPI_STA_DEVICE_FUNCTIONING;		return AE_OK;	}	return status;}所以从这里知道acpi_device 对应的status是和其hanlde的_STA 值是相等的。

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