In 2.2 the Gradebook has links under near grade in Grader report and User report.
Activity modules are strongly encouraged to add file grade.php that has mandatory argument id (module id) and optional arguments userid and itemnumber. File should redirect to the grading page for the whole module or to grading/reviewing of a particular user in this module.

Some modules add several columns in Grader report (=rows in User report). The different itemnumber is used for each column (row).

If user does not have grading permission for this module, the parameter userid is ignored and grading of the current user is displayed (this happens when student views User report)

See implementation for assignments as an example (although itemnumber is not applicable for assignments)

See attached screenshots (in the bottom of the screenshot you can see a formed link). Note that Grader report may add &gradeid=XXX to the link, where XXX may be empty if no grade exists yet. User report does not have gradeid, but it can be calculated by module if necessary knowing the other arguments