ethernet: ti: am65-cpsw-qos: add TAPRIO offload support
AM65 CPSW h/w supports Enhanced Scheduled Traffic (EST – defined in P802.1Qbv/D2.2 that later got included in IEEE 802.1Q-2018) configuration. EST allows express queue traffic to be scheduled (placed) on the wire at specific repeatable time intervals. In Linux kernel, EST configuration is done through tc command and the taprio scheduler in the net core implements a software only scheduler (SCH_TAPRIO). If the NIC is capable of EST configuration, user indicate "flag 2" in the command which is then parsed by taprio scheduler in net core and indicate that the command is to be offloaded to h/w. taprio then offloads the command to the driver by calling ndo_setup_tc() ndo ops. This patch implements ndo_setup_tc() to offload EST configuration to CPSW h/w. Currently driver supports only SetGateStates operation. EST operates on a repeating time interval generated by the CPTS EST function generator. Each Ethernet port has a global EST fetch RAM that can be configured as 2 buffers, each of 64 locations or one large buffer of 128 locations. In 2 buffer configuration, a ping pong mechanism is used to hold the active schedule (oper) in one buffer and new (admin) command in the other. Each 22-bit fetch command consists of a 14-bit fetch count (14 MSB’s) and an 8-bit priority fetch allow (8 LSB’s) that will be applied for the fetch count time in wireside clocks. Driver process each of the sched-entry in the offload command and update the fetch RAM. Driver configures duration in sched-entry into the fetch count and Gate mask into the priority fetch bits of the RAM. Then configures the CPTS EST function generator to activate the schedule. Currently driver supports only 2 buffer configuration which means driver supports a max cycle time of ~8 msec. CPSW supports a configurable number of priority queues (up to 8) and needs to be switched to this mode from the default round robin mode before EST can be offloaded. User configures these through ethtool commands (-L for changing number of queues and --set-priv-flags to disable round robin mode). Driver doesn't enable EST if pf_p0_rx_ptype_rrobin privat flag is set. The flag is common for all ports, and so can't be just overridden by taprio configuration w/o user involvement. Command fails if pf_p0_rx_ptype_rrobin is already set in the driver. Scheds (commands) configuration depends on interface speed so driver translates the duration to the fetch count based on link speed. Each schedule can be constructed with several command entries in fetch RAM depending on interval. For example if each sched has timer interval < ~130us on 1000 Mb link then each sched consumes one command and have 1:1 mapping. When Ethernet link goes down, driver purge the configuration if link is down for more than 1 second. The patch allows to update the timer and scheds memory only if it's really needed, and skip cases required the user to stop timer by configuring only shceds memory. Signed-off-by:Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org> Signed-off-by:
Murali Karicheri <m-karicheri2@ti.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
Showing
This diff is collapsed.
Please register or sign in to comment