linux-phytec-ti

net: prueth: update to support 2 queues per port at ingress/egress

One of the issue present in the current version of the firmware is that
there is a collision queue that can hold at the max one MTU sized frame.
In the case of HSR/PRP, the chances of two frames arriving simultaneously
at two ingress ports is high which results in one frame getting dropped
when the Host is still not read the previous frames in the Host interface
FIFO. Also same FIFO is shared by both PRUs making collision theoretically
possible. Instead the new design in firmware allocates 2 queues per PRU
per priority that is used exclusively by the PRU thereby avoiding
collision scenario. Tests have shown that this helps in eliminating
collision as long as the Host driver is able to drain the packet from the
queue fast enough to avoid buffer overflow. Additional buffers freed
from the collision queue is allocated to Q0-Q3 at host receive interface.

This patch makes update to the driver to use two separate interrupts per
port for switch case similar to of EMAC case. The Ingress/Egress  queue
usage is also made similar to EMAC. i.e 2 queues per priority per port
at Ingress. At the Egress, 4 queues used as in EMAC case plus a collision
queue.

The existing pcp to queue map is changed to map a group of PCPs to a queue.
Since two priority levels are supported at the ingress, 0-3 are mapped to
one queue and 4-7 to another queue for each PRU.
sw_pcp_rx_priority_queue_map[] provides this map and is written to shared
memory for firmware use.

Note that, this version of the driver is not compatible with prior version
(1.2) of the PRU firmware and will work only with PRU firmware version 1.3.
So this change has to go in sync with firmware version 1.3.

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>