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 6: DRAM Page
135
C
ONFIGURATION
R
EGISTERS
All memory controller configuration registers are 64 bit wide and they must be written using double-word
accesses. If writes smaller than 64 bits are done to a control register its contents become UNPREDICTABLE.
On the BCM1125/H, all registers of memory channel 0, except mc_config_0 are Not Implemented
.
Table 72: Memory Channel Configuration Register on BCM1250
mc_config_0 -
00_1005_1100
mc_config_1 -
00_1005_2100
Bits
Name
Default
Description
7:0
reserved
8’b0
Reserved
15:8
channel_sel
8’h0
If this field is zero the two channels are not interleaved.
If this field is non zero it specifies the address bit that selects between the two
channels, and must have a value in the range 5-35. If the channels are interleaved
the other configuration parameters must match.
19:16
bank0_map
4’h0
Value of physical address bits [31:28] that should map to 0 (1st 256MB block)
23:20
bank1_map
4’h8
Value of physical address bits [31:28] that should map to 1 (2nd 256MB block)
27:24
bank2_map
4’h9
Value of physical address bits [31:28] that should map to 2 (3rd 256MB block)
31:28
bank3_map
4’hC
Value of physical address bits [31:28] that should map to 3 (4th 256MB block)
39:32
probe_mode
8’b0
Reserved, Broadcom Use Only. Setting these bits to any value other than zero will
result in UNDEFINED behavior and can cause the ECC lines to be continually
driven regardless of the direction of the data transfer.
43:40
iob1_qsize
4’ha
These fields are used to set the range of queue entries reserved for use by I/O
Bridge 1. The two channel configuration registers set a range to give hysteresis to
the blocking.
mc_config_0
: Queue size to start blocking agents other than IOB1.
mc_config_1
: Queue size to stop blocking agents other than IOB1.
47:44
age_limit
4’h8
Maximum number of younger reads that can pass a read in the request queue,
before the read is serviced. See
.
51:48
wr_limit
4’h5
Maximum number of writes in a burst to memory before reads will be serviced. See
Section: “Memory Controller Architecture” on page 104
52
iob1_priority
1’b1
mc_config_1
: If this bit is set reads from I/O bridge 1 will be given high priority (to
reduce their latency). If clear all requests have the same priority.
mc_config_0
: Reserved.
55:53
reserved
3’b0
Reserved
59:56
cs_mode
4’h0
Chip Selection mode
0000: msb-CS mode: CS[3:0]are determined by the corresponding CS start/end+1
address registers.
1111: Interleaved-CS mode: the values of start/end+1 addresses of CS[3:0] are all
same in this mode, CS[3:0] are decoded by the two bits in the interleaved CS
position register.
1100: Mixed-CS mode: CS[1] and CS[0] are not interleaved and determined by the
corresponding start/end+1 addresses.The interleaving occurs between CS3
and CS2, determined by one bit of the interleaved CS position register. The
values of the CS[3:2] start/end+1 addresses are the same.
0110: Mixed-CS mode: CS[3] and CS[0] are not interleaved and determined by the
corresponding start/end+1 addresses. The interleaving occurs between CS2
and CS1, determined by one bit of the interleaved CS position register. The
values of the CS[2:1] start/end+1 addresses are the same.
0011: Mixed-CS mode: CS[3] and CS[2] are not interleaved and determined by the
corresponding start/end+1 addresses. The interleaving occurs between CS1
and CS0, determined by one bit of the interleaved CS position register. The
values of the CS[1:0] start/end+1 addresses are the same.