class PowerMailboxData0

GTDRIVER_MAILBOX_DATA0 (GT Driver Mailbox Data0 / Data Low)

Used for communication between the graphics driver and the PCODE (power

controller firmware code) running on the PCU (power controller).

This register must not be modified while the PCU is executing a driver

command, as indicated in the PowerMailboxInterface register.

This register was last documented formally in the Broadwell documentation

(IHD-OS-BDW-Vol 12-11.15 page 33). Later PRMs document it indirectly, by

providing its MMIO address in programming sequences.

Kaby Lake: IHD-OS-KBL-Vol 12-1.17 "Sequences for Changing CD Clock

Frequency", pages 138-139

Skylake: IHD-OS-SKL-Vol 12-05.16 "Skylake Sequences for Changing CD Clock

Frequency", pages 135-136