Merge branch 'sparx5-fdma-part-one'

Daniel Machon says:

====================
net: microchip: add FDMA library and use it for Sparx5

This patch series is the first of a 2-part series, that adds a new
common FDMA library for Microchip switch chips Sparx5 and lan966x. These
chips share the same FDMA engine, and as such will benefit from a
common library with a common implementation.  This also has the benefit
of removing a lot open-coded bookkeeping and duplicate code for the two
drivers.

Additionally, upstreaming efforts for a third chip, lan969x, will begin
in the near future. This chip will use the new library too.

In this first series, the FDMA library is introduced and used by the
Sparx5 switch driver.

 ###################
 # Example of use: #
 ###################

- Initialize the rx and tx fdma structs with values for: number of
  DCB's, number of DB's, channel ID, DB size (data buffer size), and
  total size of the requested memory. Also provide two callbacks:
  nextptr_cb() and dataptr_cb() for getting the nextptr and dataptr.

- Allocate memory using fdma_alloc_phys() or fdma_alloc_coherent().

- Initialize the DCB's with fdma_dcb_init().

- Add new DCB's with fdma_dcb_add().

- Free memory with fdma_free_phys() or fdma_free_coherent().

 #####################
 # Patch  breakdown: #
 #####################

Patch #1:  introduces library and selects it for Sparx5.

Patch #2:  includes the fdma_api.h header and removes old symbols.

Patch #3:  replaces old rx and tx variables with equivalent ones from the
           fdma struct. Only the variables that can be changed without
           breaking traffic is changed in this patch.

Patch #4:  uses the library for allocation of rx buffers. This requires
           quite a bit of refactoring in this single patch.

Patch #5:  uses the library for adding DCB's in the rx path.

Patch #6:  uses the library for freeing rx buffers.

Patch #7:  uses the library helpers in the rx path.

Patch #8:  uses the library for allocation of tx buffers. This requires
           quite a bit of refactoring in this single patch.

Patch #9:  uses the library for adding DCB's in the tx path.

Patch #10: uses the library helpers in the tx path.

Patch #11: ditches the existing linked list for storing buffer addresses,
           and instead uses offsets into contiguous memory.

Patch #12: modifies existing rx and tx functions to be direction
           independent.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>