4/29/2020
Godson 3A2000 / 3B2000 Processor User Manual
22
Page 27
Godson 3A2000 / 3B2000 Processor User Manual Part 1
Table 2-7 Correspondence between the slave device number and the module at the secondary XBAR
Slave device number default
0
No. 0 DDR2 / 3 controller
1
No. 1 DDR2 / 3 controller
2
Low-speed I / O (PCI, LPC, etc.)
3
Configuration register
The meaning of the window enable bit is shown in the following table:
Table 2-8 The space access attributes corresponding to the MMAP field
[7]
[6]
[5]
[4]
The window enable allows interleaved access to DDR. It is valid when the slave device number is 0.
Select bit configuration to route requests that hit the window address. The interleaving enable bit is required
Greater than 10
Allow block read, allow instruction fetch
It should be noted that the window configuration of the first-level XBAR cannot perform address translation for Cache consistency requests, otherwise
The address at SCache will be inconsistent with the address at the first-level cache of the processor, resulting in incorrect maintenance of Cache consistency
error.
Window hit formula: (IN_ADDR & MASK) == BASE
New address conversion formula: OUT_ADDR = (IN_ADDR & ~ MASK) | {MMAP [63:10], 10'h0}
The address window conversion register is as follows:
Table 2-9 Secondary XBAR address window conversion register table
address
register
description
Default value
3ff0 0000 CPU_WIN0_BASE CPU window 0 base address 0x0
3ff0 0008 CPU_WIN1_BASE CPU window 1 base address 0x1000_0000
3ff0 0010 CPU_WIN2_BASE CPU window 2 base address 0x0
3ff0 0018 CPU_WIN3_BASE CPU window 3 base address 0x0
3ff0 0020 CPU_WIN4_BASE CPU window 4 base address 0x0
3ff0 0028 CPU_WIN5_BASE CPU window 5 base address 0x0
3ff0 0030 CPU_WIN6_BASE CPU window 6 base address 0x0
3ff0 0038 CPU_WIN7_BASE CPU window 7 base address 0x0
3ff0 0040 CPU_WIN0_MASK CPU window 0 mask
0xffff_ffff_f000_0000
twenty three
Page 28
Godson 3A2000 / 3B2000 Processor User Manual Part 1
3ff0 0048 CPU_WIN1_MASK CPU window 1 mask
0xffff_ffff_f000_0000
3ff0 0050 CPU_WIN2_MASK CPU window 2 mask
0x0
3ff0 0058 CPU_WIN3_MASK CPU window 3 mask
0x0
3ff0 0060 CPU_WIN4_MASK CPU window 4 mask
0x0