
SCSI Functional Description
2-55
pin is asserted again if there are any stacked interrupts. This should
cause the system to re-enter the ISR.
2.2.17 Interrupt Routing
This section documents the recommended approach to RAID ready
interrupt routing for the SYM53C1010. In order to be compatible with
RAID upgrade products and the SYM53C1010, the following
requirements must be met:
When a RAID upgrade card is installed in the upgrade slot, interrupts
from the motherboard SCSI controller(s) assigned to the RAID
upgrade card must be routed to INTC/ and INTD/ of the upgrade slot
and isolated from the motherboard interrupt controller. The system
processor must not see interrupts from the SCSI controllers that are
serviced by the RAID upgrade card. An upgrade slot is one that is
connected to the interrupt routing logic for motherboard SCSI
device(s). When a PCI RAID upgrade board is installed into the
system, it will be plugged into this slot if it is to control motherboard
SCSI device(s).
The TDI pin of the upgrade slot must be connected to the INT_DIR/
pin of the SYM53C1010.
When a RAID upgrade card is not installed, interrupts from a SCSI
core must not be presented to the system’s interrupt controller using
multiple interrupt inputs.
Figure 2.6
shows an example configuration. In this example the
SYM53C1010 Dual Channel Ultra3 SCSI Multifunction Controller
contains the interrupt routing logic.
The SYM53C1010 supports four different interrupt routing modes.
Additional information for these modes may be found in the register
description of
SCSI Test One (STEST1)
description in
Chapter 4,
“Registers”
. Each SCSI core within the chip may be configured
independently by selecting the interrupt routing mode using bits [1:0] in
the
SCSI Test One (STEST1)
register within each core. Mode 0 is the
default mode and is compatible with RAID upgrade products.
If the implementation shown in
Figure 2.6
is used, INTC/ and INTD/ of
the PCI RAID upgrade slot cannot be used when a non-RAID upgrade
card is installed in the slot. If this restriction is not acceptable, additional