
4/29/2020
Godson 3A2000 / 3B2000 Processor User Manual
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According to the default register configuration, after the chip is started, the address range of 0x00000000-0x0fffffff of the CPU
(256M) mapped to the address range of 0x00000000-0x0fffffff of DDR2, 0x10000000 of CPU-
The 0x1fffffff interval (256M) is mapped to PCI 0x10000000-0x1fffffff interval, PCIDMA 0x80000000
-The address range (256M) of 0x8fffffff is mapped to the address range of 0x00000000-0x0fffffff of DDR2.
The software can implement new address space routing and conversion by modifying the corresponding configuration registers.
In addition, when there is a read access to an illegal address due to CPU speculative execution, none of the eight address windows hit.
The configuration register module returns all 0 data to the CPU to prevent the CPU from dying.
Table 2-10 Secondary XBAR default address configuration
Base address
High position
owner
0x0000_0000_0000_0000
0x0000_0000_0FFF_FFFF No. 0 DDR controller
0x0000_0000_1000_0000
0x0000_0000_1FFF_FFFF
Low-speed I / O (PCI, etc.)
2.6 Chip configuration and sampling register
The chip configuration register (Chip_config) and chip sampling register (Chip_sample) in Loongson 3A2000 provide
A mechanism to read and write the configuration of the chip.
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Godson 3A2000 / 3B2000 Processor User Manual Part 1
Table 2-11 Chip Configuration Register (Physical Address 0x1fe00180)
Bit field
Field name
access
Reset value
description
3: 0-
RW
4'b7
Keep
4 MC0_disable_ddr2_confspace
RW
1'b0
Whether to disable MC0 DDR configuration space
5-
RW
1'b0
Keep
6-
RW
1'b0
Keep
7 MC0_ddr2_resetn
RW
1'b1
MC0 software reset (active low)
8 MC0_clken
RW
1'b1
Whether to enable MC0
9 MC1_disable_ddr2_confspace
RW
1'b0
Whether to disable MC1 DDR configuration space
10-
RW
1'b0
Keep
11-
RW
1'b0
Keep
12 MC1_ddr2_resetn
RW
1'b1
MC1 software reset (active low)
13 MC1_clken
RW
1'b1
Whether to enable MC1
26:24 HT0_freq_scale_ctrl
RW
3'b111 HT controller divide by 0
27 HT0_clken
RW
1'b1
Whether to enable HT0
30:28 HT1_freq_scale_ctrl
RW
3'b111 HT controller divided by 1
31 HT1_clken
RW
1'b1
Whether to enable HT1
42:40 Node0_freq_ ctrl
RW
3'b111 node 0 frequency division
43-
RW
1'b1
46:44 Node1_freq_ ctrl
RW
3'b111 Node 1 frequency divider
47-
RW
1'b1
63:56 Cpu_version
R
2'h37 CPU version
95:64
(air)
127: 96 Pad1v8_ctrl
RW 6'h780 1v8 pad control
other
R
Keep
Table 2-12 Chip sampling register (physical address 0x1fe00190)
Bit field
Field name
access
Reset value
description
31: 0 Compcode_core
R
47:32 Sys_clkseli
R
Onboard frequency setting