2 host mac & fifo’s, 1 receive configuration register (rx_cfg), Receive configuration register (rx_cfg) – SMSC LAN9312 User Manual
Page 180: Section 14.2.2, "host, Mac & fifo’s, Receive, Configuration register (rx_cfg), Receive configuration, Register (rx_cfg), Section 14.2.2.1, "receive configuration register
High Performance Two Port 10/100 Managed Ethernet Switch with 32-Bit Non-PCI CPU Interface
Datasheet
Revision 1.4 (08-19-08)
180
SMSC LAN9312
DATASHEET
14.2.2
Host MAC & FIFO’s
This section details the Host MAC and TX/RX FIFO related System CSR’s.
These Host Bus Interface accessible registers allow for the configuration of the TX/RX FIFO’s, Host
MAC and indirect access to the complete set of Host MAC CSR’s. The Host MAC CSR’s are
accessible through the Host Bus Interface via the
Host MAC CSR Interface Command Register
and
Host MAC CSR Interface Data Register (MAC_CSR_DATA)
Note:
For more information on the TX/RX FIFO’s, refer to
Section 14.1, "TX/RX FIFO Ports"
.
Note:
The full list of Host MAC CSR’s are described in
Section 14.3, "Host MAC Control and Status
. For more information on the Host MAC, refer to
.
14.2.2.1
Receive Configuration Register (RX_CFG)
This register controls the Host MAC receive engine.
Offset:
06Ch
Size:
32 bits
BITS
DESCRIPTION
TYPE
DEFAULT
31:30
RX End Alignment (RX_EA)
This field specifies the alignment that must be maintained on the last data
transfer of a buffer. The LAN9312 will add extra DWORD’s of data up to
the alignment specified in the table below. The host is responsible for
removing these extra DWORD’s. This mechanism can be used to maintain
cache line alignment on host processors.
Note:
The desired RX End Alignment must be set before reading a
packet. The RX End Alignment can be changed between reading
receive packets, but must not be changed if the packet is partially
read.
R/W
00b
29:28
RESERVED
RO
-
27:16
RX DMA Count (RX_DMA_CNT)
This 12-bit field indicates the amount of data, in DWORD’s, to be
transferred out of the RX Data FIFO before asserting the
. After being set, this field is decremented for each DWORD of
data that is read from the RX Data FIFO. This field can be overwritten with
a new value before it reaches zero.
R/W
000h
15
Force RX Discard (RX_DUMP)
When a 1 is written to this bit, the RX Data and Status FIFO’s are cleared
of all pending data and the RX data and status pointers are cleared to zero.
Note:
Please refer to
Section 9.9.1.2, "Force Receiver Discard (Receiver
for a detailed description regarding the use
of RX_DUMP.
WO
SC
0b
BIT
VALUES
[31:30]
END ALIGNMENT
00
4-Byte Alignment
01
16-Byte Alignment
10
32-Byte Alignment
11
RESERVED