net: dsa: mv88e6xxx: depend on PTP conditionally

PTP hardware timestamping related objects are not linked when PTP
support for MV88E6xxx (NET_DSA_MV88E6XXX_PTP) is disabled, therefore
NET_DSA_MV88E6XXX should not depend on PTP_1588_CLOCK_OPTIONAL
regardless of NET_DSA_MV88E6XXX_PTP.

Instead, condition more strictly on how NET_DSA_MV88E6XXX_PTP's
dependencies are met, making sure that it cannot be enabled when
NET_DSA_MV88E6XXX=y and PTP_1588_CLOCK=m.

In other words, this commit allows NET_DSA_MV88E6XXX to be built-in
while PTP_1588_CLOCK is a module, as long as NET_DSA_MV88E6XXX_PTP is
prevented from being enabled.

Fixes: e5f31552674e ("ethernet: fix PTP_1588_CLOCK dependencies")
Signed-off-by: Johnny S. Lee <foss@jsl.io>
Signed-off-by: David S. Miller <davem@davemloft.net>

ethernet: fix PTP_1588_CLOCK dependencies

The 'imply' keyword does not do what most people think it does, it only
politely asks Kconfig to turn on another symbol, but does not prevent
it from being disabled manually or built as a loadable module when the
user is built-in. In the ICE driver, the latter now causes a link failure:

aarch64-linux-ld: drivers/net/ethernet/intel/ice/ice_main.o: in function `ice_eth_ioctl':
ice_main.c:(.text+0x13b0): undefined reference to `ice_ptp_get_ts_config'
ice_main.c:(.text+0x13b0): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `ice_ptp_get_ts_config'
aarch64-linux-ld: ice_main.c:(.text+0x13bc): undefined reference to `ice_ptp_set_ts_config'
ice_main.c:(.text+0x13bc): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `ice_ptp_set_ts_config'
aarch64-linux-ld: drivers/net/ethernet/intel/ice/ice_main.o: in function `ice_prepare_for_reset':
ice_main.c:(.text+0x31fc): undefined reference to `ice_ptp_release'
ice_main.c:(.text+0x31fc): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `ice_ptp_release'
aarch64-linux-ld: drivers/net/ethernet/intel/ice/ice_main.o: in function `ice_rebuild':

This is a recurring problem in many drivers, and we have discussed
it several times befores, without reaching a consensus. I'm providing
a link to the previous email thread for reference, which discusses
some related problems.

To solve the dependency issue better than the 'imply' keyword, introduce a
separate Kconfig symbol "CONFIG_PTP_1588_CLOCK_OPTIONAL" that any driver
can depend on if it is able to use PTP support when available, but works
fine without it. Whenever CONFIG_PTP_1588_CLOCK=m, those drivers are
then prevented from being built-in, the same way as with a 'depends on
PTP_1588_CLOCK || !PTP_1588_CLOCK' dependency that does the same trick,
but that can be rather confusing when you first see it.

Since this should cover the dependencies correctly, the IS_REACHABLE()
hack in the header is no longer needed now, and can be turned back
into a normal IS_ENABLED() check. Any driver that gets the dependency
wrong will now cause a link time failure rather than being unable to use
PTP support when that is in a loadable module.

However, the two recently added ptp_get_vclocks_index() and
ptp_convert_timestamp() interfaces are only called from builtin code with
ethtool and socket timestamps, so keep the current behavior by stubbing
those out completely when PTP is in a loadable module. This should be
addressed properly in a follow-up.

As Richard suggested, we may want to actually turn PTP support into a
'bool' option later on, preventing it from being a loadable module
altogether, which would be one way to solve the problem with the ethtool
interface.

Fixes: 06c16d89d2cb ("ice: register 1588 PTP clock device object for E810 devices")
Link: https://lore.kernel.org/netdev/20210804121318.337276-1-arnd@kernel.org/
Link: https://lore.kernel.org/netdev/CAK8P3a06enZOf=XyZ+zcAwBczv41UuCTz+=0FMf2gBz1_cOnZQ@mail.gmail.com/
Link: https://lore.kernel.org/netdev/CAK8P3a3=eOxE-K25754+fB_-i_0BZzf9a9RfPTX3ppSwu9WZXw@mail.gmail.com/
Link: https://lore.kernel.org/netdev/20210726084540.3282344-1-arnd@kernel.org/
Acked-by: Shannon Nelson <snelson@pensando.io>
Acked-by: Jacob Keller <jacob.e.keller@intel.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20210812183509.1362782-1-arnd@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: dsa: mv88e6xxx: NET_DSA_MV88E6XXX_PTP should depend on NET_DSA_MV88E6XXX

Making global2 support mandatory removed the Kconfig symbol
NET_DSA_MV88E6XXX_GLOBAL2. This symbol also served as an intermediate
symbol to make NET_DSA_MV88E6XXX_PTP depend on NET_DSA_MV88E6XXX. With
the symbol removed, the user is always asked about PTP support for
Marvell 88E6xxx switches, even if the latter support is not enabled.

Fix this by reinstating the dependency.

Fixes: 63368a7416df144b ("net: dsa: mv88e6xxx: Make global2 support mandatory")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: mv88e6xxx: Make global2 support mandatory

Early generations of the mv88e6xxx did not have the global 2
registers. In order to keep the driver slim, it was decided to make
the code for these registers optional. Over time, more generations of
switches have been added, always supporting global 2 and adding more
and more registers. No effort has been made to keep these additional
registers also optional to slim the driver down when used for older
generations. Optional global 2 now just gives additional development
and maintenance burden for no real gain.

Make global 2 support always compiled in.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Tested-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/20210127003210.663173-1-andrew@lunn.ch
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: dsa: mv88e6xxx: Remove bogus Kconfig dependency.

The mv88e6xxx is a DSA driver, and it implements DSA style time
stamping of PTP frames. It has no need of the expensive option to
enable PHY time stamping. Remove the bogus dependency.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: Brandon Streiff <brandon.streiff@ni.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: Make PTP-specific drivers depend on PTP_1588_CLOCK

Commit d1cbfd771ce8 ("ptp_clock: Allow for it to be optional") changed
all PTP-capable Ethernet drivers from `select PTP_1588_CLOCK` to `imply
PTP_1588_CLOCK`, "in order to break the hard dependency between the PTP
clock subsystem and ethernet drivers capable of being clock providers."
As a result it is possible to build PTP-capable Ethernet drivers without
the PTP subsystem by deselecting PTP_1588_CLOCK. Drivers are required to
handle the missing dependency gracefully.

Some PTP-capable Ethernet drivers (e.g., TI_CPSW) factor their PTP code
out into separate drivers (e.g., TI_CPTS_MOD). The above commit also
changed these PTP-specific drivers to `imply PTP_1588_CLOCK`, making it
possible to build them without the PTP subsystem. But as Grygorii
Strashko noted in [1]:

On Wed, Apr 22, 2020 at 02:16:11PM +0300, Grygorii Strashko wrote:

> Another question is that CPTS completely nonfunctional in this case and
> it was never expected that somebody will even try to use/run such
> configuration (except for random build purposes).

In my view, enabling a PTP-specific driver without the PTP subsystem is
a configuration error made possible by the above commit. Kconfig should
not allow users to create a configuration with missing dependencies that
results in "completely nonfunctional" drivers.

I audited all network drivers that call ptp_clock_register() but merely
`imply PTP_1588_CLOCK` and found five PTP-specific drivers that are
likely nonfunctional without PTP_1588_CLOCK:

NET_DSA_MV88E6XXX_PTP
NET_DSA_SJA1105_PTP
MACB_USE_HWSTAMP
CAVIUM_PTP
TI_CPTS_MOD

Note how these symbols all reference PTP or timestamping in their name;
this is a clue that they depend on PTP_1588_CLOCK.

Change them from `imply PTP_1588_CLOCK` [2] to `depends on PTP_1588_CLOCK`.
I'm not using `select PTP_1588_CLOCK` here because PTP_1588_CLOCK has
its own dependencies, which `select` would not transitively apply.

Additionally, remove the `select NET_PTP_CLASSIFY` from CPTS_TI_MOD;
PTP_1588_CLOCK already selects that.

[1]: https://lore.kernel.org/lkml/c04458ed-29ee-1797-3a11-7f3f560553e6@ti.com/

[2]: NET_DSA_SJA1105_PTP had never declared any type of dependency on
PTP_1588_CLOCK (`imply` or otherwise); adding a `depends on PTP_1588_CLOCK`
here seems appropriate.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Fixes: d1cbfd771ce8 ("ptp_clock: Allow for it to be optional")
Signed-off-by: Clay McClure <clay@daemons.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

treewide: Add SPDX license identifier - Makefile/Kconfig

Add SPDX license identifiers to all Make/Kconfig files which:

- Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

net: dsa: mv88e6xxx: expose switch time as a PTP hardware clock

This patch adds basic support for exposing the 32-bit timestamp counter
inside the mv88e6xxx switch as a ptp_clock.

Adjfine implemented by Richard Cochran.
Andrew Lunn: fix return value of PTP stub function.

Signed-off-by: Brandon Streiff <brandon.streiff@ni.com>
Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: mv88e6xxx: Select IRQ_DOMAIN

Some architectures may not define IRQ_DOMAIN (like m32r), fixes
undefined references to IRQ_DOMAIN functions.

Fixes: dc30c35be720 ("net: dsa: mv88e6xxx: Implement interrupt support.")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: mv88e6xxx: make global2 code optional

Since not every chip has a Global2 set of registers, make its support
optional, in which case the related functions will return -EOPNOTSUPP.

This also allows to reduce the size of the mv88e6xxx driver for devices
such as home routers embedding Ethernet chips without Global2 support.

It is present on most recent chips, thus enable its support by default.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: mv88e6xxx: Fix support for DSA tagging for older switches.

Older chips only support DSA tagging on the CPU port. New devices
support both DSA and EDSA. The driver needs to tell the core the tag
protocol to use, and configure the switch for what is available.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: mv88e6xxx: move driver in its own folder

With the upcoming support for cross-chip operations and other mv88e6xxx
enhancements, new files will be added.

Similarly to mlxsw or b53, move mv88e6xxx files into their own folder.

In the meantime, update the MAINTAINERS entry to please checkpatch.pl,
by replacing the invalid 88E6352 entry with 88E6XXX, maintained by
Andrew and myself.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>