The dp83640 PHY provides time stamp and other information via special
PHY status frames. Previously, the driver decoded the frames and then
let the network stack drop them. This works fine when the PTP messages
come over UDP.

However, when receiving PTP messages via L2 packets, this creates a
problem. The status frames use the official PTP destination MAC address,
and so they are delivered to user space along with the "real" frames,
causing confusion for applications.

This commit fixes the issue by simply dropping the PHY status frames
in the driver.
Signed-off-by: NRichard Cochran <richard.cochran@omicron.at>
Signed-off-by: NDavid S. Miller <davem@conan.davemloft.net>

If two eternal time stamp events occur at nearly the same time, the
phyter will add an extra word into the status frame. This commit fixes
the parsing code to recognize and skip over the extra word.
Signed-off-by: NRichard Cochran <richard.cochran@omicron.at>
Signed-off-by: NDavid S. Miller <davem@conan.davemloft.net>

If the dp83640 driver is not built as a module, the
MODULE_DEVICE_TABLE reference to dp83640_tbl nops out.

Since the table isn't referenced elsewhere, it it causes
the following warning:
drivers/net/phy/dp83640.c:1095: warning: ‘dp83640_tbl’ defined but not used

This apparently is common with mdio_device_id table structures,
and is avoided by using __maybe_unused annotation.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

This patch adds support for the PTP clock found on the DP83640.
The basic clock operations and one external time stamp have
been implemented.
Signed-off-by: NRichard Cochran <richard.cochran@omicron.at>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>