net: ethernet: ti: am65-cpsw: add mqprio qdisc offload in channel mode

This patch adds MQPRIO Qdisc offload in full 'channel' mode which allows
not only setting up pri:tc mapping, but also configuring TX shapers
(rate-limiting) on external port FIFOs.

The MQPRIO Qdisc offload is expected to work with or without VLAN/priority
tagged packets.

The CPSW external Port FIFO has 8 Priority queues. The rate-limit can be
set for each of these priority queues. Which Priority queue a packet is
assigned to depends on PN_REG_TX_PRI_MAP register which maps header
priority to switch priority.

The header priority of a packet is assigned via the RX_PRI_MAP_REG which
maps packet priority to header priority.

The packet priority is either the VLAN priority (for VLAN tagged packets)
or the thread/channel offset.

For simplicity, we assign the same priority queue to all queues of a
Traffic Class so it can be rate-limited correctly.

Configuration example:
 ethtool -L eth1 tx 5
 ethtool --set-priv-flags eth1 p0-rx-ptype-rrobin off

 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@1 1@2 hw 1 mode channel \
 shaper bw_rlimit min_rate 0 100mbit 200mbit max_rate 0 101mbit 202mbit

 tc qdisc replace dev eth2 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

 ip link add link eth1 name eth1.100 type vlan id 100
 ip link set eth1.100 type vlan egress 0:0 1:1 2:2 3:3 4:4 5:5 6:6 7:7

In the above example two ports share the same TX CPPI queue 0 for low
priority traffic. 3 traffic classes are defined for eth1 and mapped to:
TC0 - low priority, TX CPPI queue 0 -> ext Port 1 fifo0, no rate limit
TC1 - prio 2, TX CPPI queue 1 -> ext Port 1 fifo1, CIR=100Mbit/s, EIR=1Mbit/s
TC2 - prio 3, TX CPPI queue 2 -> ext Port 1 fifo2, CIR=200Mbit/s, EIR=2Mbit/s

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Roger Quadros <rogerq@kernel.org>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/net/ethernet/ti/am65-cpsw-nuss.c b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
index 7651f90f51f2..2e374745f239 100644
--- a/drivers/net/ethernet/ti/am65-cpsw-nuss.c
+++ b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
@@ -2127,6 +2127,9 @@ static int am65_cpsw_nuss_init_slave_ports(struct am65_cpsw_common *common)
 				dev_err(dev, "Use random MAC address\n");
 			}
 		}
+
+		/* Reset all Queue priorities to 0 */
+		writel(0, port->port_base + AM65_CPSW_PN_REG_TX_PRI_MAP);
 	}
 	of_node_put(node);