CPU-MMU

The CPU-MMU is used for virtual-to-physical memory address translation.

Introduction

The CPU-MMU diagram is shown in the following figure. A MMU can perform virtual-to-physical memory address translation. This can be used to map an external memory to a certain virtual memory area.

MMU virtual address to physical address is illustrated in the following figure. For example, if you want to access physical page 4 ~ 7 through virtual page 0 ~ 3, an MMU entry can be used to map virtual page 0 ~ 3 to physical page 4 ~ 7.

The chip provides 4 MMU entries.

• If virtual address is not included in the MMU entry, use virtual address as physical address.

• If virtual address is included in the MMU entry, physical address should be VAddress + MMU_ENTRYx_OFFSET.

Registers

REMAP以1024Byte为整数倍进行映射，如果要访问的地址VAddress在MMU entry区间内则进行remap，判断条件为 VAddress >=  REG_REMAPxBAR，且 VAddress <= REG_REMAPxEAR，映射后的地址physical address由3部分组成：

1. physical address[9:0] = VAddress[9:0];

2. physical address[19:10] = VAddress[19:10] + REG_REMAPxEAR [19:10];

3. physical address[31:20] = VAddress[31:20].

整个Register Map应该在Secure syson区间，PG时需要 retention 所有的Register，否则CPU1 Wakeup会出错 （Syson不会掉电）

Name	Address offset	Access	Description
REG_REMAP0BAR	000h	R/W	Region EMAP0 Base Address Register
REG_REMAP0EAR	004h	R/W	Region EMAP0 End Address Register
REG_REMAP0OR	008h	R/W	Remap 0 Offset Register
REG_REMAP1BAR	00Ch	R/W	Region EMAP1 Base Address Register
REG_REMAP1EAR	010h	R/W	Region EMAP1 End Address Register
REG_REMAP1OR	014h	R/W	Remap 1 Offset Register
REG_REMAP2BAR	018h	R/W	Region EMAP2 Base Address Register
REG_REMAP2EAR	01Ch	R/W	Region EMAP2 End Address Register
REG_REMAP2OR	020h	R/W	Remap 2 Offset Register
REG_REMAP3BAR	024h	R/W	Region EMAP3 Base Address Register
REG_REMAP3EAR	028h	R/W	Region EMAP3 End Address Register
REG_REMAP3OR	02Ch	R/W	Remap 3 Offset Register

REG_REMAPxBAR

• Name: Remap x Base Address Register (x={0, 1, 2, 3})

• Size: 32 bits

• Address offset: Refer to virtual address base register.

• Read/write access: R/W

Bit	Symbol	Access	Reset	Description
31:10	REMAP_BASE_x_ADDR	R/W	0x0	Remap region x base address [31:10] The region address is 1KB aligned.
9:0	RSVD	-	0	Reserved

REG_REMAPxEAR

• Name: Remap x End Address Register (x={0, 1, 2, 3})

• Size: 32 bits

• Address offset: Refer to virtual address end register.

• Read/write access: R/W

Bit	Symbol	Access	Reset	Description
31:10	REMAP_END_x_OFFSET	R/W	0x0	Remap region x end address [31:10] The region address is 1KB aligned.
9:0	RSVD	-	0	Reserved

REG_REMAPxOR

• Name: Remap x Offset Register (x={0, 1, 2, 3})

• Size: 32 bits

• Address offset: Refer to actual register address offset.

• Read/write access: R/W

Bit	Symbol	Access	Reset	Description
31:20	RSVD	-	0	Reserved
19:10	REMAP_x_OFFSET	R/W	0x0	Remap region x offset [19:10] The output address [19:10] is “Access address[19:10]+ Region_Offset[19:10]”.
9:1	RSVD	-	0	Reserved
0	REMAP_x_ENABLE	R/W	0x0	Remap region x enable