User Manual
BCM1250/BCM1125/BCM1125H
10/21/02
B r o a d c o m C o r p o r a t i o n
Document
1250_1125-UM100CB-R
Section 4: System Control and Debug Unit
Page
47
I
NTERRUPTS
The chip has a large number of interrupt sources. These come from both internal peripherals and external
signals. Each CPU has its own interrupt mapper which allows the destination of the interrupt from each source
to be set to one of the six architected hardware interrupts, the non-maskable interrupt (NMI) or the Debug
Interrupt (DINT). The mapper block includes the CPU mailbox registers described in the previous section.
Most interrupt sources are common to each interrupt mapper. The only sources that are specific to a CPU are
directed interrupts from the HyperTransport (as described below, the interrupt message includes which CPU
it should be delivered to) and the per-CPU mailbox interrupts.
The basic operation of the interrupt mapper is described in this section. Interrupts from the HyperTransport
fabric extend the basic model as described in the next section.
Section: “The Full Interrupt Mapper” on page 50
has a diagram of the complete mapper, including system, mailbox and HyperTransport sources and describes
all the associated registers.
The interrupt mapper receives the level sensitive interrupts from all sections of the part. Each source has an
associated mask bit and a 3 bit map register. If the source is interrupting and not masked out it is driven to one
of the CPU interrupt lines according to the mapping.
shows the mapping, and the corresponding IP
bit in the Cause register.
Each source maps to one CPU interrupt line. There is no limit on how many sources may map to a single CPU
line. The I5 interrupt line is also used by interrupts generated internal to the CPU, these will be merged with
any external requests. The MIPS architecture uses software based interrupt dispatch, so the software can
assign priorities to the six regular interrupt lines as it sees fit. A typical system would merge most of the system
sources on a few of the interrupt lines, and assign one source per line for sources that need rapid dispatch.
Table 18: Interrupt Mappings
Mapping
Interrupt
CP0 Cause Register
000
I0
IP[2] bit 10.
001
I1
IP[3] bit 11.
010
I2
IP[4] bit 12.
011
I3
IP[5] bit 13.
100
I4
IP[6] bit 14.
101
I5
IP[7] bit 15.
110
NMI
Reset/NMI vector, flagged in status register not cause register.
111
DINT
CPU debug interrupt, flagged in debug register.
Содержание BCM1125
Страница 18: ...BCM1250 BCM1125 BCM1125H User Manual 10 21 02 Broadcom Corporation Page xviii Document 1250_1125 UM100CB R ...
Страница 28: ...BCM1250 BCM1125 BCM1125H User Manual 10 21 02 Broadcom Corporation Page xxviii Document 1250_1125 UM100CB R ...
Страница 515: ...BCM1250 BCM1125 BCM1125H User Manual 10 21 02 Broadcom Corporation Page vii Index Document 1250_1125 UM100CB R ...