3.2.2.8.3.1. CPSW3g¶
3.2.2.8.3.1.1. Introduction¶
The TI AM62Ax family of devices have multi port Gigabit Ethernet Switch subsystem. SoCs may have more than 2 external port with selectable RGMII and RMII interfaces and an internal Communications Port Programming Interface (CPPI) port (Host port 0). Host Port 0 CPPI Packet Streaming Interface interface supports 8 TX channels and one RX channel DMA channel.
Multi port Gigabit Ethernet Switch subsystem support both independent MAC mode of operation supporting multiple independent Ethernet interfaces with complete isolation (no packet switching between external ports), or can be configured in Switch mode with IEEE 802.1Q HW bridge in managed or learning mode between each of the individual MAC ports.
The driver follows the standard Linux network interface architecture and supports the following features:
Mulitple indpendent MAC mode
Switch mode as per IEEE 802.1Q
Cut Through forwarding in Switch mode
10/100/1000 Mbps mode of operation.
Auto negotiation.
Linux NAPI support
VLAN filtering
Ethertool
CPTS/PTP as per 802.1AS-2011 (TSN)
EST/TAS offload as per 802.1Q-2018 (TSN)
IET/preemption offload as per 802.1Q-2018 (TSN)
Forwarding and Queuing Enhancements for Time-Sensitive Streams (FQTSS) as per 802.1Q-2018 previously referred to as CBS or 802.1Qav
Note
Default mode of operation is multiple indpendent MAC ports.
3.2.2.8.3.1.1.1. Supported platforms¶
SoC |
Number of external ports |
|---|---|
AM62PX |
2 external ports (CPSW3g) |
AM62AX |
2 external ports (CPSW3g) |
AM62X |
2 external ports (CPSW3g) |
AM64X |
2 external ports (CPSW3g) |
Note
3.2.2.8.3.1.2. Driver Configuration¶
Default SDK build will have these configurations enabled. In case of custom builds, please ensure following configs are enabled.
CONFIG_TI_DAVINCI_MDIO
CONFIG_TI_K3_AM65_CPSW_NUSS
CONFIG_TI_K3_AM65_CPSW_SWITCHDEV
CONFIG_TI_K3_AM65_CPTS
CONFIG_TI_AM65_CPSW_TAS
CONFIG_PHY_TI_GMII_SEL
For further details regarding the above configs, refer:
drivers/net/ethernet/ti/Kconfigdrivers/phy/ti/Kconfig
Module Build
Module build for the cpsw driver is supported. To do this, use option ‘m’ for above configs, where applicable.
3.2.2.8.3.1.3. Device tree bindings¶
The DT bindings description can be found at:
3.2.2.8.3.1.4. Multi MAC mode¶
Note
This section documents Independent MAC mode of operation with CPSW3g.
3.2.2.8.3.1.5. Promiscous Mode¶
By default promiscous mode is disabled. It can be enabled by using the below command.
Please note running a tool like tcpdump will itself enable promiscous mode.
ip link set eth0 promisc on
3.2.2.8.3.1.6. Set MacAddress manually¶
While the default MacAddress of the port is obtained from EEPROM, it’s possible to change the MacAddress manually from shell.
ip link set dev <eth0> address <macaddress>
3.2.2.8.3.1.7. Multi port Switch mode¶
Note
This section documents the Switch mode features available with CPSW3g
The Switch mode can be enabled by configuring devlink driver parameter “switch_mode” to 1/true
devlink dev param set platform/8000000.ethernet \
name switch_mode value true cmode runtime
Above setting can be done regardless of the state of Port’s netdev devices - UP/DOWN, but Port’s netdev devices have to be in UP state before joining the bridge. This is to avoid overwriting of bridge configuration as CPSW switch driver completely reloads its configuration when first port changes its state to UP.
When all the interfaces have joined the bridge - CPSW switch driver will enable marking packets with offload_fwd_mark flag.
All configuration is implemented via switchdev API.
3.2.2.8.3.1.7.1. Bridge setup¶
devlink dev param set platform/8000000.ethernet \
name switch_mode value true cmode runtime
ip link add name br0 type bridge
ip link set dev br0 type bridge ageing_time 1000
ip link set dev eth0 up
ip link set dev eth1 up
ip link set dev eth0 master br0
ip link set dev eth1 master br0
[*] bridge vlan add dev br0 vid 1 self
[*] bridge vlan add dev br0 vid 1 pvid untagged self
[*] if vlan_filtering=1, where default_pvid=1
Note: Steps [*] are mandatory.
3.2.2.8.3.1.7.2. Turn On/Off Spanning Tree Protocol (STP)¶
ip link set dev br0 type bridge stp_state 1/0
3.2.2.8.3.1.7.3. VLAN configuration¶
bridge vlan add dev br0 vid 1 self # <---- add VLAN as a Bridge Entry
bridge vlan add dev br0 vid 1 pvid untagged self # <---- add cpu port to VLAN 1
This step is mandatory for bridge/default_pvid.
3.2.2.8.3.1.7.4. Adding extra VLANs¶
untagged
bridge vlan add dev eth0 vid 100 pvid untagged master bridge vlan add dev sw0p2 vid 100 pvid untagged master bridge vlan add dev br0 vid 100 self # <---- add VLAN as a Bridge Entry bridge vlan add dev br0 vid 100 pvid untagged self # <---- Add cpu port to VLAN100
tagged
bridge vlan add dev eth0 vid 100 master bridge vlan add dev sw0p2 vid 100 master bridge vlan add dev br0 vid 100 self # <---- add VLAN as a Bridge Entry bridge vlan add dev br0 vid 100 pvid tagged self # <---- Add cpu port to VLAN100
3.2.2.8.3.1.7.5. Forwarding Data Bases (FDBs)¶
Forwarding entries for MAC addresses are automatically added on the appropriate switch port upon detection as default operation as an unmanaged bridge. For managed bridge operation manually add FDB entries as required.
Manually adding FDBs
bridge fdb add aa:bb:cc:dd:ee:ff dev eth0 master vlan 100
bridge fdb add aa:bb:cc:dd:ee:fe dev sw0p2 master # <---- Add on all VLANs
Note
For untagged traffic, the PVID is 1 by default. Therefore to add FDB entry for untagged traffic, the commands mentioned above have to use “vid 1” at the respective places.
3.2.2.8.3.1.7.6. Multicast Data Bases (MDBs)¶
Multicast entries are automatically added on the appropriate switch port upon detection as default operation as an unmanaged bridge. For managed bridge operation manually add MDB entries as required.
Manually adding MDBs
bridge mdb add dev br0 port eth0 grp 239.1.1.1 permanent vid 100
bridge mdb add dev br0 port eth0 grp 239.1.1.1 permanent # <---- Add on all VLANs
Note
For untagged traffic, the PVID is 1 by default. Therefore to add MDB entry for untagged traffic, the commands mentioned above have to use “vid 1” at the respective places.
3.2.2.8.3.1.7.7. Multicast flooding¶
CPU port mcast_flooding is always on
Turning flooding on/off on switch ports:
bridge link set dev eth0 mcast_flood on/off
3.2.2.8.3.1.7.8. Enabling Cut Through Forwarding (CTF)¶
Caution
The Cut Through configuration interface could be changed significantly in the future depending on Linux Kernel mainline development.
Cut Through feature allows forwarding packet from one external port to another without being stored in Port FIFOs thus reducing overall latency for packet forwarding.
Limitations:
Feature is only available in switch mode.
Cut Through forwarding is only supported between external ports and no support for Cut Through to host port currently.
Cut-Thru is not supported with 10/100 half-duplex.
Cut-Thru is not supported with any form of flow control.
If Intersperced Express Traffic (IET) is enabled, then Cut Through can only be enabled on an express priority queue and not on preemptible queues.
Note
Currently per port priority mask is set via debugfs entries. This may change in future.
Here is the commands to setup cut-through for priority 0 traffic:
ip link set dev eth0 down
ip link set dev eth1 down
devlink dev param set platform/8000000.ethernet name switch_mode value true cmode runtime
echo 1 > /sys/kernel/debug/8000000.ethernet/Port1/cut_thru_rx_pri_mask
echo 1 > /sys/kernel/debug/8000000.ethernet/Port1/cut_thru_tx_pri_mask
echo 1 > /sys/kernel/debug/8000000.ethernet/Port2/cut_thru_rx_pri_mask
echo 1 > /sys/kernel/debug/8000000.ethernet/Port2/cut_thru_tx_pri_mask
ethtool --set-priv-flags eth0 cut-thru on
ethtool --set-priv-flags eth1 cut-thru on
ip link add name br0 type bridge
ip link set dev br0 type bridge ageing_time 1000
ip link set dev eth0 up
sleep 1
ip link set dev eth1 up
sleep 1
ip link set dev eth0 master br0
ip link set dev eth1 master br0
ip link set dev br0 type bridge stp_state 1
ip link set dev br0 up
ip addr add 10.0.0.1/8 dev br0
bridge vlan add dev br0 vid 1 self
bridge vlan add dev br0 vid 1 pvid untagged self
The value being written to cut_thru_rx_pri_mask and cut_thru_tx_pri_mask represents the priorties queues for which cut through feature needs to be enabled. Can be configured only when all external ports are down.
With above settings, generate a iperf3 traffic from client on Port1 to client on Port 2 and observe the ethtool statistics to see cut through taking effect
root@evm:~# ethtool -S eth1 | grep col
tx_collision_frames: 1796093
tx_single_coll_frames: 0
tx_mult_coll_frames: 3
tx_excessive_collisions: 0
tx_late_collisions: 0
root@evm:~# ethtool -S eth0 | grep col
tx_collision_frames: 3
tx_single_coll_frames: 0
tx_mult_coll_frames: 2002396
tx_excessive_collisions: 52
tx_late_collisions: 23
tx_collision_frames: Enet_Pn_TxCut Enet Port n Cut Thru with and without delay (full-duplex)
tx_single_coll_frames: Enet_pn_TxCut_SAF Enet Port n Tx Store and Forward (full-duplex)
tx_mult_coll_frames: Enet_Pn_RxCut_NoDelay Enet Port n Rx Cut Thru with no delay (full-duplex)
tx_excessive_collisions: Enet_Pn_RxCut_Delay Enet Port n Rx Cut Thru with delay (full-duplex)
tx_late_collisions: Enet_Pn_RxCut_SAF Enet Port n Rx Store and Forward (full-duplex)
3.2.2.8.3.1.7.9. Transmit Traffic Control and Rate Limiting¶
The main difference between one port and multi port devices is that TX CPPI channels are shared between all network devices while External Ports FIFO are per port. The MQPRIO Qdisk can be used to assign different TX CPPI channels to different ports and this way improve over all TX performance.
The configured External Ports Fifos rate should must not be oversubscribed. If some Ext. port and Host port both send to the same priority then Ext. Ports Fifos rate for this priority has to be set as sum of Ext. and Host port rates plus some margin.
Example Host port ingress with separate TX CPPI channel per port, no QoS
switch mode: on | off
Port 1 assigned TX CPPI channel 0
Port 2 assigned TX CPPI channel 1
TX CPPI channels processing mode: Round Robin
ip link set dev eth0 down
ip link set dev eth1 down
ethtool -L eth0 tx 2
ethtool --set-priv-flags eth1 p0-rx-ptype-rrobin on
ip link set dev eth0 up
ip link set dev eth1 up
tc qdisc add dev eth0 handle 100: parent root mqprio num_tc 1 map 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 queues 1@0 hw 1 mode channel
tc qdisc add dev eth1 handle 100: parent root mqprio num_tc 1 map 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 queues 1@1 hw 1 mode channel
If TX CPPI channels processing mode is Round Robin (p0-rx-ptype-rrobin off) then Rate Limiting should for selected TX CPPI channels.
echo 800 > /sys/class/net/eth0/queues/tx-0/tx_maxrate
echo 800 > /sys/class/net/eth0/queues/tx-1/tx_maxrate
Example Host port ingress with separate TX CPPI channel per port and Rate Limiting
Linux Host send bulk and rate limited traffic to both ports. No traffic switching between P1 and P2.
to Host1│ CPSW3g Host bridge │ to Host2
│ / \ │
│ P1 P2 │
│ | | │
│ Host1 Host2 │
▼ ▼
switch mode: on
tc filters are used to assign pri for iperf3 traffic using port as filter value
VLAN tagged traffic vid=100
eth0: Ports 1
pri7 traffic routed to TX CPPI channel 7, rate limit 100Mbit
pri6 traffic routed to TX CPPI channel 6, rate limit 200Mbit
pri0-5 traffic routed to TX CPPI channel 0
pri7 traffic mapped to TC2, External Ports FIFO2, cir=100Mbit
pri6 traffic mapped to TC1, External Ports FIFO1, cir=200Mbit
pri0-5 traffic mapped to TC0, External Ports FIFO0
eth1: Ports 2
pri7 traffic routed to TX CPPI channel 5, rate limit 100Mbit
pri6 traffic routed to TX CPPI channel 4, rate limit 200Mbit
pri0-5 traffic routed to TX CPPI channel 0
pri7 traffic mapped to TC2, External Ports FIFO2, cir=100Mbit
pri6 traffic mapped to TC1, External Ports FIFO1, cir=200Mbit
pri0-5 traffic mapped to TC1, External Ports FIFO0
ip link set dev eth0 down
ip link set dev eth1 down
ethtool -L eth0 tx 8
ethtool --set-priv-flags eth1 p0-rx-ptype-rrobin off
ip link add name br0 type bridge
ip link set dev eth0 up
ip link set dev eth1 up
ip link set dev eth0 master br0
ip link set dev eth1 master br0
ip link set dev br0 up
#configure bridge...
#configure bridge vlan
ip link add link br0 name br0.100 type vlan id 100
ip link set br0.100 type vlan egress 0:0 1:1 2:2 3:3 4:4 5:5 6:6 7:7
bridge vlan add dev eth0 vid 100 master
bridge vlan add dev eth1 vid 100 master
bridge vlan add dev br0 vid 100 self
# set IP to br0.100 192.168.100.1
echo 100 > /sys/class/net/eth0/queues/tx-7/tx_maxrate
echo 200 > /sys/class/net/eth0/queues/tx-6/tx_maxrate
echo 100 > /sys/class/net/eth0/queues/tx-5/tx_maxrate
echo 200 > /sys/class/net/eth0/queues/tx-4/tx_maxrate
tc qdisc add dev br0.100 clsact
tc filter add dev br0.100 egress protocol ip prio 1 u32 match ip dport 5001 0xffff action skbedit priority 7
tc filter add dev br0.100 egress protocol ip prio 1 u32 match ip dport 5002 0xffff action skbedit priority 6
#eth0
tc qdisc add dev eth0 parent root handle 100: mqprio num_tc 3 \
map 0 0 0 0 0 0 1 2 0 0 0 0 0 0 0 0 \
queues 1@0 1@6 1@7 hw 1 mode channel \
shaper bw_rlimit min_rate 0 200mbit 100mbit
#eth1
tc qdisc add dev eth1 parent root handle 100: mqprio num_tc 3 \
map 0 0 0 0 0 0 1 2 0 0 0 0 0 0 0 0 \
queues 1@0 1@4 1@5 hw 1 mode channel \
shaper bw_rlimit min_rate 0 200mbit 100mbit
iperf3 -c 192.168.100.3 -t10 -p5001 -Tpri71 & \
iperf3 -c 192.168.100.3 -t10 -p5002 -Tpri61 & \
iperf3 -c 192.168.100.3 -t10 -p5003 -Tpri01 & \
iperf3 -c 192.168.100.2 -t10 -p5001 -Tpri72 & \
iperf3 -c 192.168.100.2 -t10 -p5002 -Tpri62
Example Bridging with TX CPPI channel and External Ports FIFO shapers
Linux Host send bulk and rate limited traffic to Host 2 (Port 2) pri3 200Mbit and Host 1 sends rate limited traffic to Host 2 (Port 2) pri3 200Mbit.
CPSW3g Host bridge │ to Host2
/ \ │ 200Mbit
P1 P2 │
| | │
Host1 Host2 │
▼
──────────────►
to Host2
200Mbit
switch mode: on
tc filters are used to assign pri for iperf3 traffic using port as filter value
VLAN tagged traffic vid=100
assume pri3 is class A and pri 2 is class B (not used)
eth0: Ports 1
pri0-7 traffic routed to TX CPPI channel 0, no HW offload
eth1: Ports 2
pri3 traffic routed to TX CPPI channel 7, rate limit 200Mbit
pri2 traffic routed to TX CPPI channel 6, rate limit 100Mbit
pri0,1,4-7 traffic routed to TX CPPI channel 0
pri3 traffic mapped to TC2, External Ports FIFO2, cir=200Mbit
pri2 traffic mapped to TC1, External Ports FIFO1, cir=100Mbit
pri0,1,4-7 traffic mapped to TC0, External Ports FIFO0
CPSW3g Host bridge configuration
ip link set dev eth0 down
ip link set dev eth1 down
ethtool -L eth0 tx 8
ethtool --set-priv-flags eth1 p0-rx-ptype-rrobin off
ip link add name br0 type bridge
ip link set dev eth0 up
ip link set dev eth1 up
ip link set dev eth0 master br0
ip link set dev eth1 master br0
ip link set dev br0 up
#configure bridge...
#configure bridge vlan
ip link add link br0 name br0.100 type vlan id 100
ip link set br0.100 type vlan egress 0:0 1:1 2:2 3:3 4:4 5:5 6:6 7:7
bridge vlan add dev eth0 vid 100 master
bridge vlan add dev eth1 vid 100 master
bridge vlan add dev br0 vid 100 self
# set IP to br0.100 192.168.100.1
echo 200 > /sys/class/net/eth0/queues/tx-7/tx_maxrate
echo 100 > /sys/class/net/eth0/queues/tx-6/tx_maxrate
tc qdisc add dev br0.100 clsact
tc filter add dev br0.100 egress protocol ip prio 1 u32 match ip dport 5002 0xffff action skbedit priority 3
#eth0
tc qdisc add dev eth0 handle 100: parent root mqprio num_tc 1 \
map 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 queues 1@0 hw 0
#eth1
tc qdisc add dev eth1 parent root handle 100: mqprio num_tc 3 \
map 0 0 1 2 0 0 0 0 0 0 0 0 0 0 0 0 \
queues 1@0 1@6 1@7 hw 1 mode channel \
shaper bw_rlimit min_rate 0 100mbit 410mbit
iperf3 -c 192.168.100.2 -t10 -p5002 -Tpri22 -t30 & \
iperf3 -c 192.168.100.2 -t10 -p5003 -Tpri02 -t30 &
Host 1 configuration
ip link add link eth0 name eth0.100 type vlan id 100
ip link set eth0.100 type vlan egress 0:0 1:1 2:2 3:3 4:4 5:5 6:6 7:7
# set IP to br0.100 192.168.100.3
tc qdisc add dev eth0.100 clsact
tc filter add dev eth0.100 egress protocol ip prio 1 u32 match ip dport 5001 0xffff action skbedit priority 3
#Real QoS configuration depends Host 2 functionality
iperf3 -c 192.168.100.2 -t10 -p5001 -Tpri3 -t30
# - or -
iperf3 -c 192.168.100.2 -t10 -p5001 -Tpri3 -t30 -u -b210M
Host 2 configuration
ip link add link eth0 name eth0.100 type vlan id 100
ip link set eth0.100 type vlan egress 0:0 1:1 2:2 3:3 4:4 5:5 6:6 7:7
# set IP to br0.100 192.168.100.3
iperf3 -s -p 5001&
iperf3 -s -p 5002&
iperf3 -s -p 5003&