https://wiki.openstreetmap.org/wiki/Tag:amenity=parking

"Each parking area feature should be mapped as a contiguous area (see One feature, one OSM element) as much as possible. Include in the area parking aisles and footways between parking spaces. Any greenery such as grass strips or trees can also be included within the parking area. Standard method to draw parking of a complex size - ones that consists of disjointed areas or has holes is to use multipolygons. Individual parking rows should not be mapped as separate parking areas."