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 7: DMA Page
187
D
ATA
M
OVER
D
ESCRIPTORS
Table 121: Data Mover Descriptor First Doubleword
dm_dscr_a
Bits
Name
Description
39:0
dst_addr
The destination address of the transfer (may be any alignment).
40
un_dest
This bit should be set for an uncached destination, and clear if the destination is cacheable
coherent. Uncached accelerated operations will be used.
41
un_src
This bit should be set for an uncached source, and clear if the source is cacheable coherent.
Uncached accelerated operations will be used.
42
interrupt
If this bit is set an interrupt will be generated at the end of the transfer.
43 reserved
Reserved
45:44
dir_dest
This indicates the direction the destination address should be moved:
00: The address is incremented
01: The address is decremented
10: The address is held constant
11: Reserved
47:46
dir_src
This indicates the direction the source address should be moved:
00: The address is incremented.
01: The address is decremented.
10: The address is held constant.
11: Reserved
48
zero_mem
If this bit is set the source parameters will be ignored, and zeros will be transferred to the destination
address.
49
prefetch
If this bit is set the destination parameters will be ignored, the data will just be read from the source.
This can be used with the L2C_SRC bit to prefetch lines from memory into the l2 cache.
Note: when used in this manner, it is most efficient if the src address is 32 byte aligned.
50
l2c_dest
If this bit is set writes to the destination buffer are marked L2_cacheable and will therefore be
allocated in the L2 on an L2 miss. (For cacheable transfers the L2 is always checked, and will
always be updated if hit).
51
l2c_src
If this bit is set reads from the source buffer are marked L2_cacheable and will therefore be
allocated in the L2 on an L2 miss. (For cacheable transfers the L2 is always checked, and will
supply the data if hit).
52
rd_bkoff
If this bit is set the data mover will backoff from a read transfer until the destination blocker has
been clear for four ZBbus cycles.
53
wr_bkoff
If this bit is set the data mover will backoff from a write transfer until the destination blocker has
been clear for four ZBbus cycles.
54
tcpcs_en
Set to enable TCP checksum (System revision PERIPH_REV3 or greater)
55
tcpcs_res
Set to reset TCP partial sum to init value at start of move (System revision PERIPH_REV3 or
greater)
56
tcpcs_ap
Set to append TCP checksum at end of move (System revision PERIPH_REV3 or greater)
57
crc_en
Set to enable CRC engine (System revision PERIPH_REV3 or greater)
58
crc_res
Set to reset partial CRC to init value at start of move (System revision PERIPH_REV3 or greater)
59
crc_ap
Set to append CRC at end of move, but before checksum (System revision PERIPH_REV3 or
greater)
60
crc_dfn
Selects which TCP/CRC definition to use (System revision PERIPH_REV3 or greater)
61
crc_xbit
Set to swap the bits within the CRC bytes prior to checksumming and appending to the packet
and/or updating the partial register. Typically only set for last block of CRC (if the CRC needs the
bitflip). (System revision PERIPH_REV3 or greater)