net: mscc: ocelot: convert to phylink
The felix DSA driver, which is a wrapper over the same hardware class as
ocelot, is integrated with phylink, but ocelot is using the plain PHY
library. It makes sense to bring together the two implementations, which
is what this patch achieves.
This is a large patch and hard to break up, but it does the following:
The existing ocelot_adjust_link writes some registers, and
felix_phylink_mac_link_up writes some registers, some of them are
common, but both functions write to some registers to which the other
doesn't.
The main reasons for this are:
- Felix switches so far have used an NXP PCS so they had no need to
write the PCS1G registers that ocelot_adjust_link writes
- Felix switches have the MAC fixed at 1G, so some of the MAC speed
changes actually break the link and must be avoided.
The naming conventions for the functions introduced in this patch are:
- vsc7514_phylink_{mac_config,validate} are specific to the Ocelot
instantiations and placed in ocelot_net.c which is built only for the
ocelot switchdev driver.
- ocelot_phylink_mac_link_{up,down} are shared between the ocelot
switchdev driver and the felix DSA driver (they are put in the common
lib).
One by one, the registers written by ocelot_adjust_link are:
DEV_MAC_MODE_CFG - felix_phylink_mac_link_up had no need to write this
register since its out-of-reset value was fine and
did not need changing. The write is moved to the
common ocelot_phylink_mac_link_up and on felix it is
guarded by a quirk bit that makes the written value
identical with the out-of-reset one
DEV_PORT_MISC - runtime invariant, was moved to vsc7514_phylink_mac_config
PCS1G_MODE_CFG - same as above
PCS1G_SD_CFG - same as above
PCS1G_CFG - same as above
PCS1G_ANEG_CFG - same as above
PCS1G_LB_CFG - same as above
DEV_MAC_ENA_CFG - both ocelot_adjust_link and ocelot_port_disable
touched this. felix_phylink_mac_link_{up,down} also
do. We go with what felix does and put it in
ocelot_phylink_mac_link_up.
DEV_CLOCK_CFG - ocelot_adjust_link and felix_phylink_mac_link_up both
write this, but to different values. Move to the common
ocelot_phylink_mac_link_up and make sure via the quirk
that the old values are preserved for both.
ANA_PFC_PFC_CFG - ocelot_adjust_link wrote this, felix_phylink_mac_link_up
did not. Runtime invariant, speed does not matter since
PFC is disabled via the RX_PFC_ENA bits which are cleared.
Move to vsc7514_phylink_mac_config.
QSYS_SWITCH_PORT_MODE_PORT_ENA - both ocelot_adjust_link and
felix_phylink_mac_link_{up,down} wrote
this. Ocelot also wrote this register
from ocelot_port_disable. Keep what
felix did, move in ocelot_phylink_mac_link_{up,down}
and delete ocelot_port_disable.
ANA_POL_FLOWC - same as above
SYS_MAC_FC_CFG - same as above, except slight behavior change. Whereas
ocelot always enabled RX and TX flow control, felix
listened to phylink (for the most part, at least - see
the 2500base-X comment).
The registers which only felix_phylink_mac_link_up wrote are:
SYS_PAUSE_CFG_PAUSE_ENA - this is why I am not sure that flow control
worked on ocelot. Not it should, since the
code is shared with felix where it does.
ANA_PORT_PORT_CFG - this is a Frame Analyzer block register, phylink
should be the one touching them, deleted.
Other changes:
- The old phylib registration code was in mscc_ocelot_init_ports. It is
hard to work with 2 levels of indentation already in, and with hard to
follow teardown logic. The new phylink registration code was moved
inside ocelot_probe_port(), right between alloc_etherdev() and
register_netdev(). It could not be done before (=> outside of)
ocelot_probe_port() because ocelot_probe_port() allocates the struct
ocelot_port which we then use to assign ocelot_port->phy_mode to. It
is more preferable to me to have all PHY handling logic inside the
same function.
- On the same topic: struct ocelot_port_private :: serdes is only used
in ocelot_port_open to set the SERDES protocol to Ethernet. This is
logically a runtime invariant and can be done just once, when the port
registers with phylink. We therefore don't even need to keep the
serdes reference inside struct ocelot_port_private, or to use the devm
variant of of_phy_get().
- Phylink needs a valid phy-mode for phylink_create() to succeed, and
the existing device tree bindings in arch/mips/boot/dts/mscc/ocelot_pcb120.dts
don't define one for the internal PHY ports. So we patch
PHY_INTERFACE_MODE_NA into PHY_INTERFACE_MODE_INTERNAL.
- There was a strategically placed:
switch (priv->phy_mode) {
case PHY_INTERFACE_MODE_NA:
continue;
which made the code skip the serdes initialization for the internal
PHY ports. Frankly that is not all that obvious, so now we explicitly
initialize the serdes under an "if" condition and not rely on code
jumps, so everything is clearer.
- There was a write of OCELOT_SPEED_1000 to DEV_CLOCK_CFG for QSGMII
ports. Since that is in fact the default value for the register field
DEV_CLOCK_CFG_LINK_SPEED, I can only guess the intention was to clear
the adjacent fields, MAC_TX_RST and MAC_RX_RST, aka take the port out
of reset, which does match the comment. I don't even want to know why
this code is placed there, but if there is indeed an issue that all
ports that share a QSGMII lane must all be up, then this logic is
already buggy, since mscc_ocelot_init_ports iterates using
for_each_available_child_of_node, so nobody prevents the user from
putting a 'status = "disabled";' for some QSGMII ports which would
break the driver's assumption.
In any case, in the eventuality that I'm right, we would have yet
another issue if ocelot_phylink_mac_link_down would reset those ports
and that would be forbidden, so since the ocelot_adjust_link logic did
not do that (maybe for a reason), add another quirk to preserve the
old logic.
The ocelot driver teardown goes through all ports in one fell swoop.
When initialization of one port fails, the ocelot->ports[port] pointer
for that is reset to NULL, and teardown is done only for non-NULL ports,
so there is no reason to do partial teardowns, let the central
mscc_ocelot_release_ports() do its job.
Tested bind, unbind, rebind, link up, link down, speed change on mock-up
hardware (modified the driver to probe on Felix VSC9959). Also
regression tested the felix DSA driver. Could not test the Ocelot
specific bits (PCS1G, SERDES, device tree bindings).
Signed-off-by: 
Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: 
David S. Miller <davem@davemloft.net>
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