According to TMZ the police report says the following.
Johnson and his ex-girlfriend were partying in Vegas and went up to his room to catch up. While in the room they got into an argument over his daughter.
At that point according to ex girlfriend Johnson started to beat her and throw her around the room. After being hit several times Johnson allegedly started to choke her to the point she said:
“If you are going to kill me squeeze harder and just do it.”
The Ex-girlfriend then passes out. When she awakes she is in the hotel hallway in just her panties and see through blouse (I know that sounds part seems odd). She starts banging on doors until someone gets her help.
Hotel security finds Johnson where he says to one of the officers.
“I’ll rip your f*cking vocal cords out!!!”
While bragging about how he will beat these charges like he did his last charges.
Once police arrived, they observed the ex girlfriend all bruised up and Johnson cut up as well. After reviewing all the statements they decided to charge Johnson with arrested for battery with strangulation.
He is scheduled to be released 5pm West Coast Time.