Halliday & Hasan (1976: 22):
[Malinowski's concept of CONTEXT OF SITUATION] has been worked over and extended by a number of linguists, the best-known treatment being perhaps that of Hymes in 'Models of interaction of language and social setting'. Hymes categorises the speech situation in terms of eight components which we may summarise as: form and content of text, setting, participants, ends (intent and effect), key, medium, genre and interactional norms. It will be noted that, in this view of the matter, the text itself forms part of the speech situation.
A more abstract interpretation, intended as a basis for DERIVING the features of the text from the features of the situation, had been offered by Halliday, McIntosh and Strevens in The Linguistic Sciences and Language Teaching. They had proposed the three headings FIELD, MODE and TENOR (to adopt the terminology preferred by Spencer and Gregory in Linguistics and Style). These are very general concepts for describing how the context of situation determines the kinds of meaning that are expressed.
Note that Martin's identification of genre with context aligns more with Hymes' concept of context than the SFL model. Indeed, in a stratified model, it is inconsistent with the notion of strata as levels of symbolic abstraction, simply because a genre, a type of language, is not more symbolically abstract than language. The inconsistency arose from Martin (1992: 488) misunderstanding strata as 'interacting modules'. See critique here.