SCP Address Translation Unit (ATU) Configuration

Introduction

The ATU provides means to convert the 32-bit logical address from the sub-system memory map to the physical address residing in the system memory map with rich security attributes.

The SCP is treated as a secure processor in the RD-Fremont platform variants and hence cannot access Root or Realm physical address space (PAS). But during the platform boot, the SCP is required to generate transactions to root PAS for configuring the CMN via the ATU.

Overview

The SCP can access the AP memory map via Address Translation Window which must be configured in the ATU. The ATU driver module in the SCP firmware configures the ATU regions.

The SCP ATU is configured with the following translation regions:

Region	Logical Address Range	Physical Address Range	PAS
Cluster Utility	0x6000_0000 - 0x6FFF_FFFF	0x2_0000_0000 - 0x2_FFFF_FFFF	Root
AP Shared SRAM	0x7000_0000 - 0x77FF_FFFF	0x0000_0000 - 0x07FF_FFFF	Root
GPC SMMU	0x7800_0000 - 0x780F_FFFF	0x3_0000_0000 - 0x3_000F_FFFF	Root
AP Peripherals	0x7810_0000 - 0x784F_FFFF	0x2F00_0000 - 0x2F3F_FFFF	Secure
CMN CFGM	0xA000_0000 - 0xDFFF_FFFF	0x1_0000_0000 - 0x1_3FFF_FFFF	Root

This SCP ATU driver implementation can be found in the in the following file in the software stack: <workspace>/scp/module/atu/

Runtime Configuration of ATU

In addition to the statically mapped translation regions if an additional ATU region needs to be configured during the runtime, then the ATU API can be used by the modules.

Please refer <workspace>/scp/module/atu/doc/atu.md