net: atlantic: Implement xdp data plane

net: atlantic: Implement xdp data plane

It supports XDP_PASS, XDP_DROP and multi buffer.

The new function aq_nic_xmit_xdpf() is used to send packet with
xdp_frame and internally it calls aq_nic_map_xdp().

AQC chip supports 32 multi-queues and 8 vectors(irq).
there are two option
1. under 8 cores and 4 tx queues per core.
2. under 4 cores and 8 tx queues per core.

Like ixgbe, these tx queues can be used only for XDP_TX, XDP_REDIRECT
queue. If so, no tx_lock is needed.
But this patchset doesn't use this strategy because getting hardware tx
queue index cost is too high.
So, tx_lock is used in the aq_nic_xmit_xdpf().

single-core, single queue, 80% cpu utilization.

  30.75%  bpf_prog_xxx_xdp_prog_tx  [k] bpf_prog_xxx_xdp_prog_tx
  10.35%  [kernel]                  [k] aq_hw_read_reg <---------- here
   4.38%  [kernel]                  [k] get_page_from_freelist

single-core, 8 queues, 100% cpu utilization, half PPS.

  45.56%  [kernel]                  [k] aq_hw_read_reg <---------- here
  17.58%  bpf_prog_xxx_xdp_prog_tx  [k] bpf_prog_xxx_xdp_prog_tx
   4.72%  [kernel]                  [k] hw_atl_b0_hw_ring_rx_receive

The new function __aq_ring_xdp_clean() is a xdp rx handler and this is
called only when XDP is attached.

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>