Data Sheet

Ethernet Controller I210 —Inline Functions
280
Software Notes:
•If SRRCTL[n].NSE is set, all buffers' addresses in a packet descriptor must be word aligned.
• Packet header can't span across buffers, therefore, the size of the header buffer must be larger
than any expected header size. Otherwise, only the part of the header fitting the header buffer is
replicated. In the case of header split mode (SRRCTL[n].DESCTYPE = 010b), a packet with a
header larger than the header buffer is not split.
• Section A.1 describes the details of the split/replicate conditions for different types of headers
according to the settings of the PSRTYPE register values.
7.1.6 Receive Packet Timestamp in Buffer
The I210 supports adding an optional tailored header before the MAC header of the packet in the
receive buffer. The 64 MSB bits of the 128 bit tailored header include a timestamp composed of the
packet reception time measured in the SYSTIML (Low DW) and SYSTIMH (High DW) registers (See
Section 7.8.3.1 for further information on SYSTIML/H operation). The 64 LSB bits of the tailored header
are reserved.
The timestamp information is placed in Host order (Little Endian) format as listed in Table 7-17.
The Timestamp in Buffer is enabled by the following settings:
• The 1588 logic must not be disabled by the TSAUXC.Disable systime flag (it should be cleared)
• The RXPBSIZE.cfg_ts_en flag should be set, allocating the extra 16 bytes in the packet buffer for
the received packets
• Specific setting of the relevant receive queues by the SRRCTL[n] registers
—The Timestamp flag should be set, instructing the hardware to post the timestamp in the
packet buffer
—If the DESCTYPE is set to any of the header split modes then the BSIZEHEADER field should be
set to a larger header buffer than 128 bytes
Packets are received to the queue are time stamped if they meet the criteria listed in Table 7-70 within
Section 7.9.1. Meeting these cases the packet is reported as follow:
• Place a 64 bit timestamp, indicating the time a packet was received by the MAC, at the beginning of
the receive buffer before the received packet.
•Set the TSIP bit in the RDESC.STATUS field of the last receive descriptor.
• Update the RDESC.Packet Type field in the last receive descriptor. Value in this field enables
identifying that this is a PTP (Precision Time Protocol) packet (this indication is only relevant for L2
packets).
• Update the RDESC.HDR_LEN and RDESC.PKT_LEN values to include size of timestamp.
Software driver should take into account the additional size of the timestamp when preparing the
receive descriptors for the relevant queue.
While the receive path is disabled, the Timestamp in Buffer mode can be disabled by clearing
RXPBSIZE.cfg_ts_en flag and issuing a Port Software Reset event (CTRL.RST).
Table 7-17. Timestamp Layout in Buffer
0 3 4 7 8 11 12 15 16...
Reserved (0x0) Reserved (0x0) SYSTIML SYSTIMH Received Packet