Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
The configuration registers for the S5935 PCI control-
ler can only be accessed under the following
conditions:
PCI BUS CONFIGURATION CYCLES
Cycles beginning with the assertion IDSEL and
FRAME# along with the two configuration command
states for C/BE[3:0] (configuration read or write)
access an individual device’s configuration space.
During the address phase of the configuration cycle
just described, the values of AD0 and AD1 identify if
the access is a Type 0 configuration cycle or a Type 1
configuration cycle. Type 0 cycles have AD0 and AD1
equal to 0 and are used to access PCI bus agents.
Type 1 configuration cycles are intended only for
bridge devices and have AD0 as a 1 with AD1 as a 0
during the address phase.
•
IDSEL high (PCI slot unique signal which iden-
tifies access to configuration registers) along
with FRAME# low.
•
Address bits A0 and A1 are 0 (Identifies a Type
0 configuration access).
•
•
Address bits A31-A11 are ignored.
Address bits A8, A9, and A10 are 0 (Function
number field of zero supported).
•
Command bits, C/BE[3:0]# must identify a con-
figuration cycle command (101X).
The S5935 PCI device is a bus agent (not a bridge)
and responds only to a Type 0 configuration accesses.
Figure 5 depicts the state of the AD bus during the
address phase of a Type 0 configuration access. The
S5935 controller does not support the multiple function
numbers field (AD[10:8]) and only responds to the all-
zero function number value.
Figure 6 describes the signal timing relationships for
configuration read cycles. Figure 7 describes configu-
ration write cycles.
Figure 43. PCI AD Bus Definition During a Type 0 Configuration Access
31
11
10
8
7
2
1
0
00
RESERVED
REGISTER
NUMBER
FUNCTION
NUMBER
TYPE 0
INTERNAL REGISTER
-
00XXXXXX
ADDRESS
(DEVICE ID, ETC.)
ONLY 000 VALUE SUPPORTED BY THIS
DEVICE.
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