
4/29/2020
Godson 3A2000 / 3B2000 Processor User Manual
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Table 11-2 PCI Control Register
Bit field
Field name
access
Reset value
Explanation
REG_40
31 tar_read_io
Read and write
(Write 1 clear)
0
Target end receives access to IO or non-prefetchable area
30 tar_read_discard
Read and write
(Write 1 clear)
0
The delay request on the target side is discarded
29 tar_resp_delay
Read and write0
When target access is given delay / split
0: After timeout
1: right away
28 tar_delay_retry
Read and write0
target access retry strategy
0: According to internal logic (see bit 29)
1: Retry now
27 tar_read_abort_en
Read and write0
If the target times out for internal read requests, whether to let target-abort respond
26:25 Reserved
-
0
24 tar_write_abort_en
Read and write0
If the target's internal write request times out, whether to respond with target-abort
23 tar_master_abort
Read and write0
Whether to allow master-abort
22:20 tar_subseq_timeout
Read and write
000
target subsequent delay timeout
000: 8 cycles
Other: Not supported
19:16 tar_init_timeout
Read and write
0000
target initial delay timeout
In PCI mode
0: 16 cycles
1-7: Disable counter
8-15: 8-15 cycle
In PCIX mode, the timeout count is fixed at 8 cycles.
delay visits
0: 8 delay access
8: 1 delay access
9: 2 delay visit
10: 3 delay visit
11: 4 delay visit
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Godson 3A2000 / 3B2000 Processor User Manual Part 1
12: 5 delay visit
13: 6 delay visit
14: 7 delay visit
15: 8 delay visit
15: 4 tar_pref_boundary
Read and write
000h
Prefetchable boundary configuration (in units of 16 bytes)
FFF: 64KB to 16byte
FFE: 64KB to 32byte
FF8: 64KB to 128byte
3 tar_pref_bound_en
Read and write0
Configuration using tar_pref_boundary
0: prefetch to device boundary
1: Use tar_pref_boundary
2 Reserved
-
0
1 tar_splitw_ctrl
Read and write0
target split write control
0: Block access other than Posted Memory Write
1: Block all access until the split is completed
0 mas_lat_timeout
Read and write0
Disable mater access timeout
0: Allow master access timeout
1: not allowed
REG_44
31: 0 Reserved
-
-