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PCI Bus Controller
22-8
Freescale Semiconductor
22.3.1.2
PCI Status/Command Register (PCISCR)—PCI Dword Addr 1
Address: 0xFC0A_8004 (PCISCR)
Access: User read/write
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R
PE
SE
MA
TR
TS
DT
DP
FC
R
66M
C
0
0
0
0
W w1c
w1c
w1c
w1c
w1c
Reset
0
0
0
0
0
0
1
0
1
0
1
0
0
0
0
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R
0
0
0
0
0
0
F
S
ST
PER
V
MW
SP
B
M
IO
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
Bits 31-27 and 24 are write-one-to-clear (w1c).
Hardware can set w1c bits, but cannot clear them.
Only PCI configuration cycles can clear w1c bits that are currently set by writing a 1 to the bit location. Writing a 1
to a w1c bit that is currently a 0 or writing a 0 to any w1c bit has no effect.
Figure 22-3. PCISCR Register
Table 22-4. PCISCR Field Descriptions
Field
Description
31
PE
Parity error detected. This bit is set when a parity error is detected, even if the PCISCR[PER] bit is cleared.
The PCI controller checks parity for address or data during the following cycles:
1. Address phase driven by an external master.
2. Write data transferred to the PCI Controller from an external master.
3. Read data transferred to the PCI Controller when operating as a PCI master.
If a data parity error is detected, this bit is set; if the PCISCR[PER] bit is set, the PCI_PERR signal is asserted.
A PCI configuration cycle writing a 1 to the bit clears it. Writing 0 has no effect.
30
SE
System error signalled. This bit is set when the PCI controller generates a PCI system error on the PCI_SERR signal.
A PCI configuration cycle writing a 1 to the bit clears it. Writing 0 has no effect.
29
MA
Master abort received. Set when the PCI controller is the PCI master and terminates a transaction (except for a
special cycle) with a master-abort. A PCI configuration cycle writing a 1 to the bit clears it. Writing 0 has no effect.
28
TR
Target abort received. Set when the PCI controller is the PCI master and a transaction terminates by a target-abort
from the currently addressed target. A PCI configuration cycle writing a 1 to the bit clears it.Writing 0 has no effect.
27
TS
Target abort signalled. Set when the PCI controller is the target and it terminates a transaction with a target-abort.
A PCI configuration cycle writing a 1 to the bit clears it. Writing 0 has no effect.
26–25
DT
PCI_DEVSEL timing. Fixed to 01. These bits encode a medium PCI_DEVSEL timing. This defines the slowest
PCI_DEVSEL timing as medium timing when the PCI controller is the target (except configuration accesses).
24
DP
Master data parity error. Applies only when the PCI controller is the master and is set only if:
• The PCI controller-as-master asserts PCI_PERR itself during a read or the PCI controller-as-master detected it
asserted by the target during a write
• The PCISCR[PER] bit is set
A PCI configuration cycle writing a 1 to the bit clears it. Writing 0 has no effect.
23
FC
Fast back-to-back capable. Fixed to 1. This read-only bit indicates that the PCI controller as target is capable of
accepting fast back-to-back transactions with other targets.
Содержание MCF54455
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