Tom Hardy will portray Elton John in an upcoming movie about the eccentric singer-songwriter, and the man writing the screenplay to the upcoming biopic says the veteran rocker has been very cooperative and accommodating.

Screenwriter Lee Hall ("Billy Elliot") tells BBC Radio 4 Elton is giving him "incredible free rein" with the script, and "hasn't interfered at all." 

He adds that John has actually been helpful in giving him the inside story of some of his darkest times.

Hall recalls that John has shared "his private diaries that nobody had seen from when he was in rehab."  He says the movie, titled "Rocketman," will tell John's story "from birth to rehab," and will include "all the trouble he got into."

John is serving as an executive producer for "Rocketman," and is developing the project through his film company, Rocket Pictures. Shooting is expected to begin later this year.