net: dsa: sja1105: don't use burst SPI reads for port statistics

The current internal sja1105 driver API is optimized for retrieving many
statistics counters at once. But the switch does not do atomic snapshotting
for them anyway.

In case we start reporting the hardware port counters through
ndo_get_stats64 as well, not just ethtool, it would be good to be able
to read individual port counters and not all of them.

Additionally, since Arnd Bergmann's commit ae1804de93f6 ("dsa: sja1105:
dynamically allocate stats structure"), sja1105_get_ethtool_stats
allocates memory dynamically, since struct sja1105_port_status was
deemed to consume too much stack memory. That is not ideal.
The large structure is only needed because of the burst read.
If we read statistics one by one, we can consume less memory, and
we can avoid dynamic allocation.

Additionally, latency-sensitive interfaces such as PTP operations (for
phc2sys) might suffer if the SPI mutex is being held for too long, which
happens in the case of SPI burst reads. By reading counters one by one,
we give a chance for higher priority processes to preempt and take the
SPI bus mutex for accessing the PTP clock.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: stop reporting the queue levels in ethtool port counters

The queue levels are not counters, but instead they represent the
occupancy of the MAC TX queues. Having these in ethtool port counters is
not helpful, so remove them.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

dsa: sja1105: fix semicolon.cocci warnings

drivers/net/dsa/sja1105/sja1105_ethtool.c:481:11-12: Unneeded semicolon

Remove unneeded semicolon.

Generated by: scripts/coccinelle/misc/semicolon.cocci

Fixes: ae1804de93f6 ("dsa: sja1105: dynamically allocate stats structure")
CC: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

dsa: sja1105: dynamically allocate stats structure

The addition of sja1105_port_status_ether structure into the
statistics causes the frame size to go over the warning limit:

drivers/net/dsa/sja1105/sja1105_ethtool.c:421:6: error: stack frame size of 1104 bytes in function 'sja1105_get_ethtool_stats' [-Werror,-Wframe-larger-than=]

Use dynamic allocation to avoid this.

Fixes: 336aa67bd027 ("net: dsa: sja1105: show more ethtool statistics counters for P/Q/R/S")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: show more ethtool statistics counters for P/Q/R/S

It looks like the P/Q/R/S series supports some more counters,
generically named "Ethernet statistics counter", which we were not
printing. Add them.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: Rename sja1105_spi_send_packed_buf to sja1105_xfer_buf

The most commonly called function in the driver is long due for a
rename. The "packed" word is redundant (it doesn't make sense to
transfer an unpacked structure, since that is in CPU endianness yadda
yadda), and the "spi" word is also redundant since argument 2 of the
function is SPI_READ or SPI_WRITE.

As for the sja1105_spi_send_long_packed_buf function, it is only being
used from sja1105_spi.c, so remove its global prototype.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: Fix status initialization in sja1105_get_ethtool_stats

Clang warns:

drivers/net/dsa/sja1105/sja1105_ethtool.c:316:39: warning: suggest
braces around initialization of subobject [-Wmissing-braces]
struct sja1105_port_status status = {0};
^
{}
1 warning generated.

One way to fix these warnings is to add additional braces like Clang
suggests; however, there has been a bit of push back from some
maintainers[1][2], who just prefer memset as it is unambiguous, doesn't
depend on a particular compiler version[3], and properly initializes all
subobjects. Do that here so there are no more warnings.

[1]: https://lore.kernel.org/lkml/022e41c0-8465-dc7a-a45c-64187ecd9684@amd.com/
[2]: https://lore.kernel.org/lkml/20181128.215241.702406654469517539.davem@davemloft.net/
[3]: https://lore.kernel.org/lkml/20181116150432.2408a075@redhat.com/

Fixes: 52c34e6e125c ("net: dsa: sja1105: Add support for ethtool port counters")
Link: https://github.com/ClangBuiltLinux/linux/issues/471
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: Add support for ethtool port counters

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>