sfc/siena: fix null pointer dereference in efx_hard_start_xmit

Like in previous patch for sfc, prevent potential (but unlikely) NULL
pointer dereference.

Fixes: 12804793b17c ("sfc: decouple TXQ type from label")
Reported-by: Tianhao Zhao <tizhao@redhat.com>
Signed-off-by: Íñigo Huguet <ihuguet@redhat.com>
Link: https://lore.kernel.org/r/20220915141958.16458-1-ihuguet@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

sfc/siena: Remove duplicate check on segments

Siena only supports software TSO. This means more code can be deleted,
as pointed out by the Smatch static checker warning:
drivers/net/ethernet/sfc/siena/tx.c:184 __efx_siena_enqueue_skb()
warn: duplicate check 'segments' (previous on line 158)

Fixes: 956f2d86cb37 ("sfc/siena: Remove build references to missing functionality")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/kernel-janitors/YoH5tJMnwuGTrn1Z@kili/
Signed-off-by: Martin Habets <habetsm.xilinx@gmail.com>
Link: https://lore.kernel.org/r/165294463549.23865.4557617334650441347.stgit@palantir17.mph.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

sfc/siena: Rename functions in nic_common.h to avoid conflicts with sfc

For siena use efx_siena_ as the function prefix.
efx_nic_update_stats_atomic is only used in efx_common.c, so move
it there.
efx_nic_copy_stats is not used in Siena, so it is removed.

Signed-off-by: Martin Habets <habetsm.xilinx@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

sfc/siena: Rename peripheral functions to avoid conflicts with sfc

For siena use efx_siena_ as the function prefix.
This patch covers selftest.h, ptp.h, net_driver.h and ethtool_common.h.
efx_ethtool_fill_self_tests() can become static.
Some functions in ptp.c can also become static.
Rename loopback_mode in net_driver.h.

Signed-off-by: Martin Habets <habetsm.xilinx@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

sfc/siena: Rename RX/TX functions to avoid conflicts with sfc

For siena use efx_siena_ as the function prefix.
Several functions are not used in Siena, so they are removed.

Use a Siena specific variable name for module parameter
efx_separate_tx_channels.
Move efx_fini_tx_queue() to avoid a forward declaration of
efx_dequeue_buffer().

Signed-off-by: Martin Habets <habetsm.xilinx@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

sfc/siena: Rename functions in efx headers to avoid conflicts with sfc

When building with allyesconfig there are many identical
symbol names.
For siena use efx_siena_ as the function and variable prefix
to avoid build errors.

efx_mtd_remove_partition can become static as it is no longer called
from other files.
efx_ticks_to_usecs and efx_xmit_done_single are not used in Siena, so
they are removed.
Several functions are only used inside efx_channels.c for Siena so
they can become static.

Signed-off-by: Martin Habets <habetsm.xilinx@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

sfc/siena: Remove build references to missing functionality

Functionality not supported or needed on Siena includes:
- Anything for EF100
- EF10 specifics such as register access, PIO and TSO offload.
Also only bind to Siena NICs.

Remove EF10 specifics from nic.h.
The functions that start with efx_farch_ will be removed from sfc.ko
with a subsequent patch.
Add the efx_ prefix to siena_prepare_flush() to make it consistent
with the other APIs.

Signed-off-by: Martin Habets <habetsm.xilinx@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

sfc: Copy shared files needed for Siena (part 2)

These are the files starting with m through w.
No changes are done, those will be done with subsequent commits.

Signed-off-by: Martin Habets <habetsm.xilinx@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>