RX MAC LITE
This component is used to implement the Ethernet MAC layer on the receiving side. Thanks to the modular architecture (RX MAC LITE + Adapter), it can be connected to a supported ETH Hard IP block or implement the MAC layer separately. The implementation may include differences from the Ethernet standard.
Architecture
RX MAC LITE contains several components that analyze the received frame (CRC, MAC address, length) and check for errors. The Ethernet frame is stored in the buffer (store and forward), if it does not contain errors, it is sent to the output interface along with the metadata, otherwise the frame is discarded. Some of these components are optional. The whole module can be controlled by SW using MI registers (see chapter Register Map).
Description of RX MAC LITE submodules:
CTRL Unit - controls the whole module through MI registers
Enabler - enables the receiving of Ethernet frames, if disabled, incoming frames are discarded
CRC Cutter - cuts the CRC of the received Ethernet frame (optional)
Length Check - calculates and checks the length of the received Ethernet frame
CRC Check - checks the CRC of the received Ethernet frame (optional, it is not available in OFM repository, extra license required))
MAC Check - extracts and checks the MAC address of the received Ethernet frame (optional)
Time Stamp - assigns a time stamp to the received Ethernet frame (optional)
Error masking - allows to mask individual errors of the received Ethernet frame
Buffer - store and forward buffer is used to store the received Ethernet frame
Stats Unit - contains statistical counters accessible through MI registers
Adapter
The adapter allows you to connect the RX MAC LITE to various variants of the PCS/PMA layer of the Ethernet or various Ethernet Hard IPs. The main task of the adapter is to convert the selected input bus to the MFB bus. Currently, several variants of the adapter are implemented:
UMII Adapter - connects Ethernet PCS/PMA layer with MII interface for various speeds (XGMII, XLGMII, CDGMII,…)
CMAC Adapter - connects CMAC Hard IP, which is used in Xilinx UltraScale+ FPGA for 100 Gbps Ethernet (Uses MFB not LBUS!)
AVST Adapter - connects E-Tile Hard IP, which is used in Intel Stratix 10 and Agilex FPGA for up to 100 Gbps Ethernet
MAC Segmented Adapter (WIP) - connects F-Tile Hard IP, which is used in Intel Agilex FPGA for up to 400 Gbps Ethernet
Register Map
It is possible to configure RX MAC LITE on the fly, but if you want to make changes atomically, you should disable RX MAC LITE first. You can set MAC check mode, RX MAC LITE error mask, minimal and maximal frame length. After you are done you can enable RX MAC LITE. You can also write all valid MAC addresses into MAC memory, but the MAC memory can be accessed by software only when the RX MAC LITE is disabled!
You can read number of received, correct, discarded and discarded due to buffer overflow frames or number of correctly received bytes. You have to sample the counters first and then you can read their content. RX MAC LITE has four frame counters: Total Received Frames Counter (TRFC), Correct Frames Counter (CFC), Discarded Frames Counter (DFC) and Counter of Frames Discarded due to Buffer Overflow (BODFC) and the byte counter: Octets Received OK Counter (OROC).
Note
If the RX MAC LITE unit is enabled, these counters will have a floating content. For this reason, it is necessary to strobe their actual values at the one moment into the counter registers. Software tool is then able to read those registers.
Offset |
Name of register |
|---|---|
0x00 |
Total Received Frames Counter - low part (TRFCL) |
0x04 |
Correct Frames Counter - low part (CFCL) |
0x08 |
Discarded Frames Counter - low part (DFCL) |
0x0C |
Counter of frames discarded due to buffer overflow - low part (BODFCL) |
0x10 |
Total Received Frames Counter - high part (TRFCH) |
0x14 |
Correct Frames Counter - high part (CFCH) |
0x18 |
Discarded Frames Counter - high part (DFCH) |
0x1C |
Counter of frames discarded due to buffer overflow - high part (BODFCH) |
0x20 |
Enable register |
0x24 |
Error mask register |
0x28 |
Status register |
0x2C |
Command register |
0x30 |
Minimum frame length allowed |
0x34 |
Frame MTU |
0x38 |
MAC address check mode |
0x3C |
Octets Received OK Counter - low part (OROCL) |
0x40 |
Octets Received OK Counter - high part (OROCH) |
0x80 |
Memory of available MAC addresses |
Total Received Frames Counter - low part (TRFCL)
This is the low part of counter that holds number of all arrived frames including those being received at the moment. (TRFC = CFC + DFC)
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
31 |
Counter value |
R |
Current counter value |
Correct Frames Counter - low part (CFCL)
This is the low part of counter that holds number of frames that passed sampling and all controls (was found to be correct) and are forwarded to the RX MAC LITE’s output. (CFC = TRFC - DFC)
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
31 |
Counter value |
R |
Current counter value |
Discarded Frames Counter - low part (DFCL)
This is the low part of counter that holds number of frames that did NOT pass sampling or any control (was found to be NOT correct) and are NOT forwarded to the RX MAC LITE’s output. (DFC = TRFC - CFC)
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
31 |
Counter value |
R |
Current counter value |
Counter of frames discarded due to buffer overflow - low part (BODFCL)
This is the low part of counter that holds number of frames that were discarded due to buffer overflow.
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
31 |
Counter value |
R |
Current counter value |
Total Received Frames Counter - high part (TRFCH)
This is the high part of counter that holds number of all arrived frames including those being received at the moment. (TRFC = CFC + DFC)
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
31 |
Counter value |
R |
Current counter value |
Correct Frames Counter - high part (CFCH)
This is the high part of counter that holds number of frames that passed sampling and all controls (was found to be correct) and are forwarded to the RX MAC LITE’s output. (CFC = TRFC - DFC)
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
31 |
Counter value |
R |
Current counter value |
Discarded Frames Counter - high part (DFCH)
This is the high part of counter that holds number of frames that did NOT pass sampling or any control (was found to be NOT correct) and are NOT forwarded to the RX MAC LITE’s output. (DFC = TRFC - CFC)
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
31 |
Counter value |
R |
Current counter value |
Counter of frames discarded due to buffer overflow - high part (BODFCH)
This is the high part of counter that holds number of frames that were discarded due to buffer overflow.
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
31 |
Counter value |
R |
Current counter value |
Enable register
The value stored in this register determines whether the RX MAC LITE unit is enabled or not.
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
0 |
Enable |
RW |
Assert this bit to change the RX MAC LITE status to ‘enabled’. Clear this bit to change the RX MAC LITE status to ‘disabled’. As soon as the RX MAC LITE status is set to ‘enabled’ the RX MAC LITE unit starts working. |
1 |
31 |
Reserved |
R |
Reserved bits. |
Error mask register
This register specifies which controls will be done over incoming frames. The value stored in this register determines which kinds of errors cause the frame discarding.
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
0 |
ADAPTER_ERROR |
RW |
This bit signals whether the error notified by adapter will cause the frame discarding. Assert this bit to allow frame discarding. Clear this bit to mask this error. |
1 |
1 |
CRC_ERROR |
RW |
This bit signals whether the CRC check error will cause the frame discarding. Assert this bit to allow frame discarding. Clear this bit to mask this error. |
2 |
2 |
MINTU_CHECK |
RW |
This bit enables the minimum frame length check. If the incoming frame length is less than the RX MAC LITE minimum frame length register, the frame will be discarded. |
3 |
3 |
MTU_CHECK |
RW |
This bit enables the MTU frame length check. If the incoming frame length is greater than the RX MAC LITE frame MTU register, the frame will be discarded. |
4 |
4 |
MAC_CHECK |
RW |
This bit enables the frame MAC address check. If the incoming frame destination MAC address doesn’t pass the control, the frame will be discarded. |
5 |
31 |
Reserved |
R |
Reserved bits. |
Status register
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
0 |
MFIFO_OVF |
RW |
This bit is asserted in case the MFIFO (frame metadata) overflow has occured. Bit reset is performed by writing operation. |
1 |
1 |
DFIFO_OVF |
RW |
This bit is asserted in case the DFIFO (frame data) overflow has occured. Bit reset is performed by writing operation. |
2 |
3 |
DEBUG |
RW |
Reserved (tied to zero). |
4 |
6 |
Obsolete |
R |
Ignore these bits. |
7 |
7 |
Link Status |
R |
Information about the link status (0=no link, 1=link ok). |
8 |
21 |
Reserved |
R |
Reserved bits. |
22 |
22 |
INBANDFCS |
R |
FCS field removing flag (0 → FCS is removed, 1 → FSC isn’t removed). |
23 |
27 |
MAC_COUNT |
R |
Number of MAC addresses that can be placed into CAM (at most 16). |
28 |
31 |
Reserved |
R |
Reserved bits. |
Command register
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
7 |
Command |
W |
Write a command into this register. |
8 |
31 |
Reserved |
R |
Reserved bits. |
Command definition:
0x01 - CMD STROBE COUNTERS: Writing this constant into the command register will cause that the current frame counters’ values will be stored into the frame counter registers at the same moment.
0x02 - CMD RESET COUNTERS: Writing this constant into the command register will cause that the frame counters will be reset.
0x03 - CMD SWITCH ADDRESS SPACE: Switch the output address space (more information here TODO RFC COUNTERS link)
Minimum frame length allowed
This register specifies the minimal frame length allowed (MINTU). The frame length includes the length of Ethernet frame including FCS - according to the XGMII specification it is the length of <data> part of XGMII data stream without IFG, preamble, SFD or EFD. Default value is 64.
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
15 |
Min. length |
RW |
The minimal frame length allowed. |
16 |
31 |
Reserved |
R |
Reserved bits. |
Maximum frame length allowed
This register specifies the maximal frame length allowed (MTU). The frame length includes the length of Ethernet frame including FCS - according to the XGMII specification it is the length of <data> part of XGMII data stream without IFG, preamble, SFD or EFD. Default value is 64. Default value is 1526.
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
15 |
Max. length |
RW |
The maximal frame length allowed. |
16 |
31 |
Reserved |
R |
Reserved bits. |
MAC address check mode
This register specifies the mode of MAC address checking.
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
1 |
Check mode |
RW |
The MAC address checking mode. |
2 |
31 |
Reserved |
R |
Reserved bits. |
MAC address checking mode definition:
0x00 - MODE 0: All MACs can pass (promiscuous mode).
0x01 - MODE 1: Only frames with valid MAC addresses can pass (see MAC memory).
0x02 - MODE 2: MODE 1 + All brodcast frames can pass.
0x03 - MODE 3: MODE 2 + All multicast frames can pass.
Octets Received OK Counter - low part (OROCL)
This is the low part of counter that holds number of data octets in frames that were successfully received. This does not include octets in frames received with MAC, CRC, MINTU, MTU, CRC or CGMII errors according the settings of Error mask register. This counter is incremented when a new packet is successfully received and the length of the currently received packet is added. The counted length of the packets always includes the length of CRC and vice versa.
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
31 |
Counter value |
R |
Current counter value |
Octets Received OK Counter - high part (OROCH)
This is the high part of counter that holds number of data octets in frames that were successfully received. This does not include octets in frames received with MAC, CRC, MINTU, MTU, CRC or CGMII errors according the settings of Error mask register. This counter is incremented when a new packet is successfully received and the length of the currently received packet is added. The counted length of the packets always includes the length of CRC and vice versa.
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
31 |
Counter value |
R |
Current counter value |
Memory of available MAC addresses
This memory contains all available MAC addresses for network interface.
From |
To |
Name |
Access |
Description |
|---|---|---|---|---|
0 |
47 |
MAC address |
RW |
The MAC address. |
48 |
48 |
Valid bit |
RW |
MAC address is valid when asserted. |
To write the MAC address item properly you must first write low 32 bits and then high 16 bits. If you would not do it right way the MAC have not been written. Memory can contains up to 16 MAC addresses (it depends on MAC_COUNT generic). Each MAC address is stored on two address positions. The lower address contains the lower 4 bytes and the upper contains the 2 upper bytes and valid bit. Only valid MAC addresses are used for matching.
Warning
The MAC memory can be accessed by software only when the RX MAC LITE is disabled!
Ports and Generics
- ENTITY RX_MAC_LITE IS
- Generics
PortsGeneric
Type
Default
Description
=====
MFB CONFIGURATION:
=====
RX MFB configuration, allows you to set the required data width according to the selected Ethernet standard.
RX_REGIONS
natural
4
RX MFB: number of regions in word, must be power of 2
RX_REGION_SIZE
natural
8
RX MFB: number of blocks in region, must be power of 2
RX_BLOCK_SIZE
natural
8
RX MFB: number of items in block, must be >= 4 and power of 2
RX_ITEM_WIDTH
natural
8
RX MFB: width of one item in bits, must be 8
=====
TX MFB configuration, by default the same as RX. Useful, for example,
=====
for enlargement data width from 128b (RX) to 512b (TX).
TX_REGIONS
natural
RX_REGIONS
TX MFB: number of regions in word, by default same as RX
TX_REGION_SIZE
natural
RX_REGION_SIZE
TX MFB: number of blocks in region, by default same as RX
TX_BLOCK_SIZE
natural
RX_BLOCK_SIZE
TX MFB: number of items in block, by default same as RX
TX_ITEM_WIDTH
natural
RX_ITEM_WIDTH
TX MFB: width of one item in bits, by default same as RX
RESIZE_BUFFER
boolean
false
If true, the MFB bus doubles data width (number of regions) before the packet buffer (on RX_CLK). RESIZE_BUFFER feature is allowed only when the MFB bus increases (TX MFB width >= 2x RX MFB width) and the following conditions must apply: RX_BLOCK_SIZE=TX_BLOCK_SIZE, RX_ITEM_WIDTH=TX_ITEM_WIDTH
=====
OTHERS CONFIGURATION:
=====
=====
NETWORK_PORT_ID
natural
0
ID of this network port, it is inserted into the packet metadata.
PKT_MTU_BYTES
natural
16384
Maximum allowed size of packet in bytes.
CRC_IS_RECEIVED
boolean
true
Set true when CRC is part of frames in RX MFB bus.
CRC_CHECK_EN
boolean
true
Enable of CRC checking, CRC_IS_RECEIVED must be true. When is disable, resources are ~60% lower.
CRC_REMOVE_EN
boolean
true
Enable of CRC removing, CRC_IS_RECEIVED must be true.
MAC_CHECK_EN
boolean
true
Enable of MAC checking.
MAC_COUNT
natural
4
Number of maximum MAC address in CAM memory, maximum value is 16.
TIMESTAMP_EN
boolean
true
Enable of timestamping frames.
DEVICE
string
“STRATIX10”
Select correct FPGA device. ULTRASCALE
Port
Type
Mode
Description
=====
CLOCK AND RESET
=====
=====
RX_CLK
std_logic
in
Clock for RX MFB interface
RX_RESET
std_logic
in
Reset synchronized with RX_CLK
TX_CLK
std_logic
in
Clock for TX MFB interface
TX_RESET
std_logic
in
Reset synchronized with TX_CLK
=====
RX MAC LITE ADAPTER INTERFACES
=====
RX_MFB_DATA
std_logic_vector(RX_REGIONS*RX_REGION_SIZE*RX_BLOCK_SIZE*RX_ITEM_WIDTH-1 downto 0)
in
RX MFB: data word with frames (packets)
RX_MFB_SOF_POS
std_logic_vector(RX_REGIONS*max(1,log2(RX_REGION_SIZE))-1 downto 0)
in
RX MFB: Start Of Frame (SOF) flag for each MFB region
RX_MFB_EOF_POS
std_logic_vector(RX_REGIONS*max(1,log2(RX_REGION_SIZE*RX_BLOCK_SIZE))-1 downto 0)
in
RX MFB: End Of Frame (EOF) flag for each MFB region
RX_MFB_SOF
std_logic_vector(RX_REGIONS-1 downto 0)
in
RX MFB: SOF position for each MFB region in MFB blocks
RX_MFB_EOF
std_logic_vector(RX_REGIONS-1 downto 0)
in
RX MFB: EOF position for each MFB region in MFB items
RX_MFB_ERROR
std_logic_vector(RX_REGIONS-1 downto 0)
in
RX MFB: Error flag for each MFB region, valid with EOF
RX_MFB_SRC_RDY
std_logic
in
RX MFB: source ready of each MFB bus, don’t support gaps inside frame!
=====
RX STATUS INTERFACE
=====
=====
ADAPTER_LINK_UP
std_logic
in
Link Up flag input, active when link is up
=====
INPUT TIMESTAMP INTERFACE (FROM TSU)
=====
=====
TSU_TS_NS
std_logic_vector(64-1 downto 0)
in
Timestamp in nanosecond (new) format, more info in TSU.
TSU_TS_DV
std_logic
in
Valid flag of timestamp.
=====
TX INTERFACES
=====
=====
TX_MFB_DATA
std_logic_vector(TX_REGIONS*TX_REGION_SIZE*TX_BLOCK_SIZE*TX_ITEM_WIDTH-1 downto 0)
out
TX MFB: data word with frames (packets)
TX_MFB_SOF_POS
std_logic_vector(TX_REGIONS*max(1,log2(TX_REGION_SIZE))-1 downto 0)
out
TX MFB: Start Of Frame (SOF) flag for each MFB region
TX_MFB_EOF_POS
std_logic_vector(TX_REGIONS*max(1,log2(TX_REGION_SIZE*TX_BLOCK_SIZE))-1 downto 0)
out
TX MFB: End Of Frame (EOF) flag for each MFB region
TX_MFB_SOF
std_logic_vector(TX_REGIONS-1 downto 0)
out
TX MFB: SOF position for each MFB region in MFB blocks
TX_MFB_EOF
std_logic_vector(TX_REGIONS-1 downto 0)
out
TX MFB: EOF position for each MFB region in MFB items
TX_MFB_SRC_RDY
std_logic
out
TX MFB: source ready of each MFB bus
TX_MFB_DST_RDY
std_logic
in
TX MFB: destination ready of each MFB bus
=====
TX MVB METADATA INTERFACE
=====
Metadata MVB bus is valid for each transmitted frame (EOF) from this module. Description of DATA bits are in eth_hdr_pack package.
TX_MVB_DATA
std_logic_vector(TX_REGIONS*ETH_RX_HDR_WIDTH-1 downto 0)
out
TX MVB: data word with MVB items. Description of DATA bits are in eth_hdr_pack package.
TX_MVB_VLD
std_logic_vector(TX_REGIONS-1 downto 0)
out
TX MVB: valid of each MVB item. There is one item for each packet on the TX MFB.
TX_MVB_SRC_RDY
std_logic
out
TX MVB: source ready of each MVB bus
TX_MVB_DST_RDY
std_logic
in
TX MVB: destination ready of each MVB bus
=====
OUTPUT LINK STATUS INTERFACE
=====
=====
LINK_UP
std_logic
out
Active when link is up
INCOMING_FRAME
std_logic
out
Active while receiving a frame
=====
MI32 INTERFACE
=====
=====
MI_CLK
std_logic
in
Clock for MI bus
MI_RESET
std_logic
in
Reset synchronized with MI_CLK
MI_DWR
std_logic_vector(32-1 downto 0)
in
MI bus: data from master to slave (write data)
MI_ADDR
std_logic_vector(32-1 downto 0)
in
MI bus: slave address
MI_RD
std_logic
in
MI bus: byte enable
MI_WR
std_logic
in
MI bus: read request
MI_BE
std_logic_vector(4-1 downto 0)
in
MI bus: write request
MI_DRD
std_logic_vector(32-1 downto 0)
out
MI bus: ready of slave module
MI_ARDY
std_logic
out
MI bus: data from slave to master (read data)
MI_DRDY
std_logic
out
MI bus: valid of MI_DRD data signal