ALAMEDA, Calif. -- The Oakland Raiders have signed tight end Darren Waller to a multiyear contract extension, the team announced Wednesday night.

Waller is expected to earn about $9 million per season on what amounts to a three-year extension, according to the NFL Network. Waller, a sixth-round draft pick of the Baltimore Ravens in 2015 out of Georgia Tech, was scheduled to become a restricted free agent this coming offseason.

Waller vowed to give "all I got" in one of the videos the team posted after the extension was announced.

"I'm gonna give you all I got."

Darren Waller's message to #RaiderNation comes from the heart. pic.twitter.com/q3jzP1AXSx

— Oakland Raiders () October 17, 2019

Waller, who served a pair of suspensions for failed drug tests while with the Ravens, has gone public with his fight for sobriety, which reached two years during training camp. His story was one of the main storylines on HBO's "Hard Knocks" series this summer. He was signed by the Raiders off the Ravens' practice squad last Nov. 27 and won Oakland's starting tight end job in camp.

After entering this season with 18 catches for 178 yards and two touchdowns in 22 career games, Waller has caught a team-leading 37 passes for 359 yards through five games for the 3-2 Raiders, including a 13-catch effort for 134 yards in Minnesota in Week 3.

"It's difficult, but it's easier now because I know, I feel like I have a purpose in my life," Waller told ESPN earlier this season. "I feel like I live with an intention. Before, I didn't really know who I wanted to be or what I stood for or what I was trying to accomplish.

"I'm trying to change the course of generations in my family that have been having the same habits."

Raiders coach Jon Gruden said Waller is an inspiration, not only for his teammates but for others battling substance abuse.

"He's really a rookie playing tight end; he was a wide receiver in college," Gruden said last week. "He sat out of football for a year. He leads the league in receiving right now at that position. If you watched him block, I don't know if there's a better tight end in football, really."