Uploading your accepted manuscript to White Rose Research Online is supported by many publishers - the RoMEO service lists hundreds of publishers which allow the final peer reviewed manuscript of your work to be made openly available. Some have an embargo period, some, like the Royal Society, Elsevier and Springer, do not have an embargo period. Most publishers don't allow open posting of the final, as published, PDF of a work with the publisher formatting etc - though some do.