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Author SHA1 Message Date
Vladimir Oltean
0ba83aa037 net: dsa: sja1105: the PTP_CLK extts input reacts on both edges
It looks like the sja1105 external timestamping input is not as generic
as we thought. When fed a signal with 50% duty cycle, it will timestamp
both the rising and the falling edge. When fed a short pulse signal,
only the timestamp of the falling edge will be seen in the PTPSYNCTS
register, because that of the rising edge had been overwritten. So the
moral is: don't feed it short pulse inputs.

Luckily this is not a complete deal breaker, as we can still work with
1 Hz square waves. But the problem is that the extts polling period was
not dimensioned enough for this input signal. If we leave the period at
half a second, we risk losing timestamps due to jitter in the measuring
process. So we need to increase it to 4 times per second.

Also, the very least we can do to inform the user is to deny any other
flags combination than with PTP_RISING_EDGE and PTP_FALLING_EDGE both
set.

Fixes: 747e5eb31d ("net: dsa: sja1105: configure the PTP_CLK pin as EXT_TS or PER_OUT")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-05-06 15:03:14 -07:00
Clay McClure
b6d49cab44 net: Make PTP-specific drivers depend on PTP_1588_CLOCK
Commit d1cbfd771c ("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: d1cbfd771c ("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>
2020-05-01 15:27:51 -07:00
Vladimir Oltean
a6af77637a net: dsa: sja1105: add broadcast and per-traffic class policers
This patch adds complete support for manipulating the L2 Policing Tables
from this switch. There are 45 table entries, one entry per each port
and traffic class, and one dedicated entry for broadcast traffic for
each ingress port.

Policing entries are shareable, and we use this functionality to support
shared block filters.

We are modeling broadcast policers as simple tc-flower matches on
dst_mac. As for the traffic class policers, the switch only deduces the
traffic class from the VLAN PCP field, so it makes sense to model this
as a tc-flower match on vlan_prio.

How to limit broadcast traffic coming from all front-panel ports to a
cumulated total of 10 Mbit/s:

tc qdisc add dev sw0p0 ingress_block 1 clsact
tc qdisc add dev sw0p1 ingress_block 1 clsact
tc qdisc add dev sw0p2 ingress_block 1 clsact
tc qdisc add dev sw0p3 ingress_block 1 clsact
tc filter add block 1 flower skip_sw dst_mac ff:ff:ff:ff:ff:ff \
	action police rate 10mbit burst 64k

How to limit traffic with VLAN PCP 0 (also includes untagged traffic) to
100 Mbit/s on port 0 only:

tc filter add dev sw0p0 ingress protocol 802.1Q flower skip_sw \
	vlan_prio 0 action police rate 100mbit burst 64k

The broadcast, VLAN PCP and port policers are compatible with one
another (can be installed at the same time on a port).

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-30 11:44:01 -07:00
Vladimir Oltean
a7cc081cab net: dsa: sja1105: add configuration of port policers
This adds partial configuration support for the L2 Policing Table. Out
of the 45 policing entries, only 5 are used (one for each port), in a
shared manner. All 8 traffic classes, and the broadcast policer, are
redirected to a common instance which belongs to the ingress port.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-30 11:44:00 -07:00
Vladimir Oltean
336aa67bd0 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>
2020-03-29 22:04:20 -07:00
Vladimir Oltean
c279c7261a net: dsa: sja1105: implement the port MTU callbacks
On this switch, the frame length enforcements are performed by the
ingress policers. There are 2 types of those: regular L2 (also called
best-effort) and Virtual Link policers (an ARINC664/AFDX concept for
defining L2 streams with certain QoS abilities). To avoid future
confusion, I prefer to call the reset reason "Best-effort policers",
even though the VL policers are not yet supported.

We also need to change the setup of the initial static config, such that
DSA calls to .change_mtu (which are expensive) become no-ops and don't
reset the switch 5 times.

A driver-level decision is to unconditionally allow single VLAN-tagged
traffic on all ports. The CPU port must accept an additional VLAN header
for the DSA tag, which is again a driver-level decision.

The policers actually count bytes not only from the SDU, but also from
the Ethernet header and FCS, so those need to be accounted for as well.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-27 16:07:25 -07:00
Vladimir Oltean
747e5eb31d net: dsa: sja1105: configure the PTP_CLK pin as EXT_TS or PER_OUT
The SJA1105 switch family has a PTP_CLK pin which emits a signal with
fixed 50% duty cycle, but variable frequency and programmable start time.

On the second generation (P/Q/R/S) switches, this pin supports even more
functionality. The use case described by the hardware documents talks
about synchronization via oneshot pulses: given 2 sja1105 switches,
arbitrarily designated as a master and a slave, the master emits a
single pulse on PTP_CLK, while the slave is configured to timestamp this
pulse received on its PTP_CLK pin (which must obviously be configured as
input). The difference between the timestamps then exactly becomes the
slave offset to the master.

The only trouble with the above is that the hardware is very much tied
into this use case only, and not very generic beyond that:
 - When emitting a oneshot pulse, instead of being told when to emit it,
   the switch just does it "now" and tells you later what time it was,
   via the PTPSYNCTS register. [ Incidentally, this is the same register
   that the slave uses to collect the ext_ts timestamp from, too. ]
 - On the sync slave, there is no interrupt mechanism on reception of a
   new extts, and no FIFO to buffer them, because in the foreseen use
   case, software is in control of both the master and the slave pins,
   so it "knows" when there's something to collect.

These 2 problems mean that:
 - We don't support (at least yet) the quirky oneshot mode exposed by
   the hardware, just normal periodic output.
 - We abuse the hardware a little bit when we expose generic extts.
   Because there's no interrupt mechanism, we need to poll at double the
   frequency we expect to receive a pulse. Currently that means a
   non-configurable "twice a second".

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-23 22:15:07 -07:00
Vladimir Oltean
0a7e984c92 net: dsa: sja1105: make the AVB table dynamically reconfigurable
The AVB table contains the CAS_MASTER field (to be added in the next
patch) which decides the direction of the PTP_CLK pin.

Reconfiguring this field dynamically is highly preferable to having to
reset the switch and upload a new static configuration, so we add
support for exactly that.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-23 22:15:07 -07:00
Vladimir Oltean
4bfa1616d9 net: dsa: sja1105: make future_base_time a common helper
Because the PTP_CLK pin starts toggling only at a time higher than the
current PTP clock, this helper from the time-aware shaper code comes in
handy here as well. We'll use it to transform generic user input for the
perout request into valid input for the sja1105 hardware.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-23 22:15:07 -07:00
Vladimir Oltean
79d5511cc0 net: dsa: sja1105: unconditionally set DESTMETA and SRCMETA in AVB table
These fields configure the destination and source MAC address that the
switch will put in the Ethernet frames sent towards the CPU port that
contain RX timestamps for PTP.

These fields do not enable the feature itself, that is configured via
SEND_META0 and SEND_META1 in the General Params table.

The implication of this patch is that the AVB Params table will always
be present in the static config. Which doesn't really hurt.

This is needed because in a future patch, we will add another field from
this table, CAS_MASTER, for configuring the PTP_CLK pin function. That
can be configured irrespective of whether RX timestamping is enabled or
not, so always having this table present is going to simplify things a
bit.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-23 22:15:07 -07:00
Vladimir Oltean
ffe10e679c net: dsa: sja1105: Add support for the SGMII port
SJA1105 switches R and S have one SerDes port with an 802.3z
quasi-compatible PCS, hardwired on port 4. The other ports are still
MII/RMII/RGMII. The PCS performs rate adaptation to lower link speeds;
the MAC on this port is hardwired at gigabit. Only full duplex is
supported.

The SGMII port can be configured as part of the static config tables, as
well as through a dedicated SPI address region for its pseudo-clause-22
registers. However it looks like the static configuration is not
able to change some out-of-reset values (like the value of MII_BMCR), so
at the end of the day, having code for it is utterly pointless. We are
just going to use the pseudo-C22 interface.

Because the PCS gets reset when the switch resets, we have to add even
more restoration logic to sja1105_static_config_reload, otherwise the
SGMII port breaks after operations such as enabling PTP timestamping
which require a switch reset.

>From PHYLINK perspective, the switch supports *only* SGMII (it doesn't
support 1000Base-X). It also doesn't expose access to the raw config
word for in-band AN in registers MII_ADV/MII_LPA.
It is able to work in the following modes:
 - Forced speed
 - SGMII in-band AN slave (speed received from PHY)
 - SGMII in-band AN master (acting as a PHY)

The latter mode is not supported by this patch. It is even unclear to me
how that would be described. There is some code for it left in the
patch, but 'an_master' is always passed as false.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-20 08:55:21 -07:00
Vladimir Oltean
ee9d0cb6c4 net: dsa: sja1105: Avoid error message for unknown PHY mode on disabled ports
When sja1105_init_mii_settings iterates over the port list, it prints
this message for disabled ports, because they don't have a valid
phy-mode:

[    4.778702] sja1105 spi2.0: Unsupported PHY mode unknown!

Suggested-by: Andrew Lunn <andrew@lunn.ch>
Suggested-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-19 21:37:40 -07:00
Vladimir Oltean
ec8582d134 net: dsa: sja1105: move MAC configuration to .phylink_mac_link_up
The switches supported so far by the driver only have non-SerDes ports,
so they should be configured in the PHYLINK callback that provides the
resolved PHY link parameters.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-14 20:49:48 -07:00
David S. Miller
1d34357931 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Minor overlapping changes, nothing serious.

Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-12 22:34:48 -07:00
Oleksij Rempel
ca68e1384f net: dsa: sja1105: add 100baseT1_Full support
Validate 100baseT1_Full to make this driver work with TJA1102 PHY.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Acked-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-03 14:54:05 -08:00
Vladimir Oltean
52c0d4e306 net: dsa: sja1105: Don't destroy not-yet-created xmit_worker
Fixes the following NULL pointer dereference on PHY connect error path
teardown:

[    2.291010] sja1105 spi0.1: Probed switch chip: SJA1105T
[    2.310044] sja1105 spi0.1: Enabled switch tagging
[    2.314970] fsl-gianfar soc:ethernet@2d90000 eth2: error -19 setting up slave phy
[    2.322463] 8<--- cut here ---
[    2.325497] Unable to handle kernel NULL pointer dereference at virtual address 00000018
[    2.333555] pgd = (ptrval)
[    2.336241] [00000018] *pgd=00000000
[    2.339797] Internal error: Oops: 5 [#1] SMP ARM
[    2.344384] Modules linked in:
[    2.347420] CPU: 1 PID: 64 Comm: kworker/1:1 Not tainted 5.5.0-rc5 #1
[    2.353820] Hardware name: Freescale LS1021A
[    2.358070] Workqueue: events deferred_probe_work_func
[    2.363182] PC is at kthread_destroy_worker+0x4/0x74
[    2.368117] LR is at sja1105_teardown+0x70/0xb4
[    2.372617] pc : [<c036cdd4>]    lr : [<c0b89238>]    psr: 60000013
[    2.378845] sp : eeac3d30  ip : eeab1900  fp : eef45480
[    2.384036] r10: eef4549c  r9 : 00000001  r8 : 00000000
[    2.389227] r7 : eef527c0  r6 : 00000034  r5 : ed8ddd0c  r4 : ed8ddc40
[    2.395714] r3 : 00000000  r2 : 00000000  r1 : eef4549c  r0 : 00000000
[    2.402204] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
[    2.409297] Control: 10c5387d  Table: 8020406a  DAC: 00000051
[    2.415008] Process kworker/1:1 (pid: 64, stack limit = 0x(ptrval))
[    2.421237] Stack: (0xeeac3d30 to 0xeeac4000)
[    2.612635] [<c036cdd4>] (kthread_destroy_worker) from [<c0b89238>] (sja1105_teardown+0x70/0xb4)
[    2.621379] [<c0b89238>] (sja1105_teardown) from [<c10717fc>] (dsa_switch_teardown.part.1+0x48/0x74)
[    2.630467] [<c10717fc>] (dsa_switch_teardown.part.1) from [<c1072438>] (dsa_register_switch+0x8b0/0xbf4)
[    2.639984] [<c1072438>] (dsa_register_switch) from [<c0b89c30>] (sja1105_probe+0x2ac/0x464)
[    2.648378] [<c0b89c30>] (sja1105_probe) from [<c0b11a5c>] (spi_drv_probe+0x7c/0xa0)
[    2.656081] [<c0b11a5c>] (spi_drv_probe) from [<c0a26ab8>] (really_probe+0x208/0x480)
[    2.663871] [<c0a26ab8>] (really_probe) from [<c0a26f0c>] (driver_probe_device+0x78/0x1c4)
[    2.672093] [<c0a26f0c>] (driver_probe_device) from [<c0a24c48>] (bus_for_each_drv+0x80/0xc4)
[    2.680574] [<c0a24c48>] (bus_for_each_drv) from [<c0a26810>] (__device_attach+0xd0/0x168)
[    2.688794] [<c0a26810>] (__device_attach) from [<c0a259d8>] (bus_probe_device+0x84/0x8c)
[    2.696927] [<c0a259d8>] (bus_probe_device) from [<c0a25f24>] (deferred_probe_work_func+0x84/0xc4)
[    2.705842] [<c0a25f24>] (deferred_probe_work_func) from [<c03667b0>] (process_one_work+0x22c/0x560)
[    2.714926] [<c03667b0>] (process_one_work) from [<c0366d8c>] (worker_thread+0x2a8/0x5d4)
[    2.723059] [<c0366d8c>] (worker_thread) from [<c036cf94>] (kthread+0x150/0x154)
[    2.730416] [<c036cf94>] (kthread) from [<c03010e8>] (ret_from_fork+0x14/0x2c)

Checking for NULL pointer is correct because the per-port xmit kernel
threads are created in sja1105_probe immediately after calling
dsa_register_switch.

Fixes: a68578c20a ("net: dsa: Make deferred_xmit private to sja1105")
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-29 21:58:46 -08:00
Russell King
5b502a7b29 net: dsa: propagate resolved link config via mac_link_up()
Propagate the resolved link configuration down via DSA's
phylink_mac_link_up() operation to allow split PCS/MAC to work.

Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-27 12:02:14 -08:00
David S. Miller
b3f7e3f23a Merge ra.kernel.org:/pub/scm/linux/kernel/git/netdev/net 2020-01-19 22:10:04 +01:00
Vladimir Oltean
27afe0d34e net: dsa: sja1105: Don't error out on disabled ports with no phy-mode
The sja1105_parse_ports_node function was tested only on device trees
where all ports were enabled. Fix this check so that the driver
continues to probe only with the ports where status is not "disabled",
as expected.

Fixes: 8aa9ebccae ("net: dsa: Introduce driver for NXP SJA1105 5-port L2 switch")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-01-17 13:22:12 +01:00
Florian Fainelli
4d776482ec net: dsa: Get information about stacked DSA protocol
It is possible to stack multiple DSA switches in a way that they are not
part of the tree (disjoint) but the DSA master of a switch is a DSA
slave of another. When that happens switch drivers may have to know this
is the case so as to determine whether their tagging protocol has a
remove chance of working.

This is useful for specific switch drivers such as b53 where devices
have been known to be stacked in the wild without the Broadcom tag
protocol supporting that feature. This allows b53 to continue supporting
those devices by forcing the disabling of Broadcom tags on the outermost
switches if necessary.

The get_tag_protocol() function is therefore updated to gain an
additional enum dsa_tag_protocol argument which denotes the current
tagging protocol used by the DSA master we are attached to, else
DSA_TAG_PROTO_NONE for the top of the dsa_switch_tree.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-01-08 16:01:13 -08:00
Vladimir Oltean
a68578c20a net: dsa: Make deferred_xmit private to sja1105
There are 3 things that are wrong with the DSA deferred xmit mechanism:

1. Its introduction has made the DSA hotpath ever so slightly more
   inefficient for everybody, since DSA_SKB_CB(skb)->deferred_xmit needs
   to be initialized to false for every transmitted frame, in order to
   figure out whether the driver requested deferral or not (a very rare
   occasion, rare even for the only driver that does use this mechanism:
   sja1105). That was necessary to avoid kfree_skb from freeing the skb.

2. Because L2 PTP is a link-local protocol like STP, it requires
   management routes and deferred xmit with this switch. But as opposed
   to STP, the deferred work mechanism needs to schedule the packet
   rather quickly for the TX timstamp to be collected in time and sent
   to user space. But there is no provision for controlling the
   scheduling priority of this deferred xmit workqueue. Too bad this is
   a rather specific requirement for a feature that nobody else uses
   (more below).

3. Perhaps most importantly, it makes the DSA core adhere a bit too
   much to the NXP company-wide policy "Innovate Where It Doesn't
   Matter". The sja1105 is probably the only DSA switch that requires
   some frames sent from the CPU to be routed to the slave port via an
   out-of-band configuration (register write) rather than in-band (DSA
   tag). And there are indeed very good reasons to not want to do that:
   if that out-of-band register is at the other end of a slow bus such
   as SPI, then you limit that Ethernet flow's throughput to effectively
   the throughput of the SPI bus. So hardware vendors should definitely
   not be encouraged to design this way. We do _not_ want more
   widespread use of this mechanism.

Luckily we have a solution for each of the 3 issues:

For 1, we can just remove that variable in the skb->cb and counteract
the effect of kfree_skb with skb_get, much to the same effect. The
advantage, of course, being that anybody who doesn't use deferred xmit
doesn't need to do any extra operation in the hotpath.

For 2, we can create a kernel thread for each port's deferred xmit work.
If the user switch ports are named swp0, swp1, swp2, the kernel threads
will be named swp0_xmit, swp1_xmit, swp2_xmit (there appears to be a 15
character length limit on kernel thread names). With this, the user can
change the scheduling priority with chrt $(pidof swp2_xmit).

For 3, we can actually move the entire implementation to the sja1105
driver.

So this patch deletes the generic implementation from the DSA core and
adds a new one, more adequate to the requirements of PTP TX
timestamping, in sja1105_main.c.

Suggested-by: Florian Fainelli <f.fainelli@gmail.com>
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>
2020-01-05 15:13:13 -08:00
Vladimir Oltean
0a51826c6e net: dsa: sja1105: Always send through management routes in slot 0
I finally found out how the 4 management route slots are supposed to
be used, but.. it's not worth it.

The description from the comment I've just deleted in this commit is
still true: when more than 1 management slot is active at the same time,
the switch will match frames incoming [from the CPU port] on the lowest
numbered management slot that matches the frame's DMAC.

My issue was that one was not supposed to statically assign each port a
slot. Yes, there are 4 slots and also 4 non-CPU ports, but that is a
mere coincidence.

Instead, the switch can be used like this: every management frame gets a
slot at the right of the most recently assigned slot:

Send mgmt frame 1 through S0:    S0 x  x  x
Send mgmt frame 2 through S1:    S0 S1 x  x
Send mgmt frame 3 through S2:    S0 S1 S2 x
Send mgmt frame 4 through S3:    S0 S1 S2 S3

The difference compared to the old usage is that the transmission of
frames 1-4 doesn't need to wait until the completion of the management
route. It is safe to use a slot to the right of the most recently used
one, because by protocol nobody will program a slot to your left and
"steal" your route towards the correct egress port.

So there is a potential throughput benefit here.

But mgmt frame 5 has no more free slot to use, so it has to wait until
_all_ of S0, S1, S2, S3 are full, in order to use S0 again.

And that's actually exactly the problem: I was looking for something
that would bring more predictable transmission latency, but this is
exactly the opposite: 3 out of 4 frames would be transmitted quicker,
but the 4th would draw the short straw and have a worse worst-case
latency than before.

Useless.

Things are made even worse by PTP TX timestamping, which is something I
won't go deeply into here. Suffice to say that the fact there is a
driver-level lock on the SPI bus offsets any potential throughput gains
that parallelism might bring.

So there's no going back to the multi-slot scheme, remove the
"mgmt_slot" variable from sja1105_port and the dummy static assignment
made at probe time.

While passing by, also remove the assignment to casc_port altogether.
Don't pretend that we support cascaded setups.

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>
2020-01-05 15:13:12 -08:00
David S. Miller
31d518f35e Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Simple overlapping changes in bpf land wrt. bpf_helper_defs.h
handling.

Signed-off-by: David S. Miller <davem@davemloft.net>
2019-12-31 13:37:13 -08:00
Vladimir Oltean
19d1f0ed74 net: dsa: sja1105: Empty the RX timestamping queue on PTP settings change
When disabling PTP timestamping, don't reset the switch with the new
static config until all existing PTP frames have been timestamped on the
RX path or dropped. There's nothing we can do with these afterwards.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-12-30 20:31:40 -08:00
Vladimir Oltean
1e762bd278 net: dsa: sja1105: Use PTP core's dedicated kernel thread for RX timestamping
And move the queue of skb's waiting for RX timestamps into the ptp_data
structure, since it isn't needed if PTP is not compiled.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-12-30 20:31:40 -08:00
Vladimir Oltean
54fa49ee88 net: dsa: sja1105: Reconcile the meaning of TPID and TPID2 for E/T and P/Q/R/S
For first-generation switches (SJA1105E and SJA1105T):
- TPID means C-Tag (typically 0x8100)
- TPID2 means S-Tag (typically 0x88A8)

While for the second generation switches (SJA1105P, SJA1105Q, SJA1105R,
SJA1105S) it is the other way around:
- TPID means S-Tag (typically 0x88A8)
- TPID2 means C-Tag (typically 0x8100)

In other words, E/T tags untagged traffic with TPID, and P/Q/R/S with
TPID2.

So the patch mentioned below fixed VLAN filtering for P/Q/R/S, but broke
it for E/T.

We strive for a common code path for all switches in the family, so just
lie in the static config packing functions that TPID and TPID2 are at
swapped bit offsets than they actually are, for P/Q/R/S. This will make
both switches understand TPID to be ETH_P_8021Q and TPID2 to be
ETH_P_8021AD. The meaning from the original E/T was chosen over P/Q/R/S
because E/T is actually the one with public documentation available
(UM10944.pdf).

Fixes: f9a1a7646c ("net: dsa: sja1105: Reverse TPID and TPID2")
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-12-30 20:15:02 -08:00
Vladimir Oltean
d00bdc0a88 net: dsa: sja1105: Remove restriction of zero base-time for taprio offload
The check originates from the initial implementation which was not based
on PTP time but on a standalone clock source. In the meantime we can now
program the PTPSCHTM register at runtime with the dynamic base time
(actually with a value that is 200 ns smaller, to avoid writing DELTA=0
in the Schedule Entry Points Parameters Table). And we also have logic
for moving the actual base time in the future of the PHC's current time
base, so the check for zero serves no purpose, since even if the user
will specify zero, that's not what will end up in the static config
table where the limitation is.

Fixes: 86db36a347 ("net: dsa: sja1105: Implement state machine for TAS with PTP clock source")
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-12-30 20:13:11 -08:00
Vladimir Oltean
5a47f588ee net: dsa: sja1105: Really make the PTP command read-write
When activating tc-taprio offload on the switch ports, the TAS state
machine will try to check whether it is running or not, but will find
both the STARTED and STOPPED bits as false in the
sja1105_tas_check_running function. So the function will return -EINVAL
(an abnormal situation) and the kernel will keep printing this from the
TAS FSM workqueue:

[   37.691971] sja1105 spi0.1: An operation returned -22

The reason is that the underlying function that gets called,
sja1105_ptp_commit, does not actually do a SPI_READ, but a SPI_WRITE. So
the command buffer remains initialized with zeroes instead of retrieving
the hardware state. Fix that.

Fixes: 41603d78b3 ("net: dsa: sja1105: Make the PTP command read-write")
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-12-30 20:11:28 -08:00
Vladimir Oltean
9fcf024dd6 net: dsa: sja1105: Take PTP egress timestamp by port, not mgmt slot
The PTP egress timestamp N must be captured from register PTPEGR_TS[n],
where n = 2 * PORT + TSREG. There are 10 PTPEGR_TS registers, 2 per
port. We are only using TSREG=0.

As opposed to the management slots, which are 4 in number
(SJA1105_NUM_PORTS, minus the CPU port). Any management frame (which
includes PTP frames) can be sent to any non-CPU port through any
management slot. When the CPU port is not the last port (#4), there will
be a mismatch between the slot and the port number.

Luckily, the only mainline occurrence with this switch
(arch/arm/boot/dts/ls1021a-tsn.dts) does have the CPU port as #4, so the
issue did not manifest itself thus far.

Fixes: 47ed985e97 ("net: dsa: sja1105: Add logic for TX timestamping")
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-12-30 20:10:20 -08:00
David S. Miller
adf6f8cb3f Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Merge in networking bug fixes for merge window.

Signed-off-by: David S. Miller <davem@davemloft.net>
2019-11-25 14:57:26 -08:00
Oleksij Rempel
9bca3a0a92 net: dsa: sja1105: fix sja1105_parse_rgmii_delays()
This function was using configuration of port 0 in devicetree for all ports.
In case CPU port was not 0, the delay settings was ignored. This resulted not
working communication between CPU and the switch.

Fixes: f5b8631c29 ("net: dsa: sja1105: Error out if RGMII delays are requested in DT")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-11-25 10:56:12 -08:00
Vladimir Oltean
abfb228ae6 net: dsa: sja1105: Simplify reset handling
We don't really need 10k species of reset. Remove everything except cold
reset which is what is actually used. Too bad the hardware designers
couldn't agree to use the same bit field for rev 1 and rev 2, so the
(*reset_cmd) function pointer is there to stay.

However let's simplify the prototype and give it a struct dsa_switch (we
want to avoid forward-declarations of structures, in this case struct
sja1105_private, wherever we can).

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-11-14 15:11:17 -08:00
Vladimir Oltean
86db36a347 net: dsa: sja1105: Implement state machine for TAS with PTP clock source
Tested using the following bash script and the tc from iproute2-next:

	#!/bin/bash

	set -e -u -o pipefail

	NSEC_PER_SEC="1000000000"

	gatemask() {
		local tc_list="$1"
		local mask=0

		for tc in ${tc_list}; do
			mask=$((${mask} | (1 << ${tc})))
		done

		printf "%02x" ${mask}
	}

	if ! systemctl is-active --quiet ptp4l; then
		echo "Please start the ptp4l service"
		exit
	fi

	now=$(phc_ctl /dev/ptp1 get | gawk '/clock time is/ { print $5; }')
	# Phase-align the base time to the start of the next second.
	sec=$(echo "${now}" | gawk -F. '{ print $1; }')
	base_time="$(((${sec} + 1) * ${NSEC_PER_SEC}))"

	tc qdisc add dev swp5 parent root handle 100 taprio \
		num_tc 8 \
		map 0 1 2 3 5 6 7 \
		queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 \
		base-time ${base_time} \
		sched-entry S $(gatemask 7) 100000 \
		sched-entry S $(gatemask "0 1 2 3 4 5 6") 400000 \
		clockid CLOCK_TAI flags 2

The "state machine" is a workqueue invoked after each manipulation
command on the PTP clock (reset, adjust time, set time, adjust
frequency) which checks over the state of the time-aware scheduler.
So it is not monitored periodically, only in reaction to a PTP command
typically triggered from a userspace daemon (linuxptp). Otherwise there
is no reason for things to go wrong.

Now that the timecounter/cyclecounter has been replaced with hardware
operations on the PTP clock, the TAS Kconfig now depends upon PTP and
the standalone clocksource operating mode has been removed.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-11-14 14:50:35 -08:00
Vladimir Oltean
41603d78b3 net: dsa: sja1105: Make the PTP command read-write
The PTPSTRTSCH and PTPSTOPSCH bits are actually readable and indicate
whether the time-aware scheduler is running or not. We will be using
that for monitoring the scheduler in the next patch, so refactor the PTP
command API in order to allow that.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-11-14 14:50:35 -08:00
Vladimir Oltean
2eea1fa82f net: dsa: sja1105: Print the reset reason
Sometimes it can be quite opaque even for me why the driver decided to
reset the switch. So instead of adding dump_stack() calls each time for
debugging, just add a reset reason to sja1105_static_config_reload
calls which gets printed to the console.

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>
2019-11-12 19:53:07 -08:00
Vladimir Oltean
af580ae2dc net: dsa: sja1105: Disallow management xmit during switch reset
The purpose here is to avoid ptp4l fail due to this condition:

  timed out while polling for tx timestamp
  increasing tx_timestamp_timeout may correct this issue, but it is likely caused by a driver bug
  port 1: send peer delay request failed

So either reset the switch before the management frame was sent, or
after it was timestamped as well, but not in the middle.

The condition may arise either due to a true timeout (i.e. because
re-uploading the static config takes time), or due to the TX timestamp
actually getting lost due to reset. For the former we can increase
tx_timestamp_timeout in userspace, for the latter we need this patch.

Locking all traffic during switch reset does not make sense at all,
though. Forcing all CPU-originated traffic to potentially block waiting
for a sleepable context to send > 800 bytes over SPI is not a good idea.
Flows that are autonomously forwarded by the switch will get dropped
anyway during switch reset no matter what. So just let all other
CPU-originated traffic be dropped as well.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-11-11 12:45:31 -08:00
Vladimir Oltean
6cf99c13ea net: dsa: sja1105: Restore PTP time after switch reset
The PTP time of the switch is not preserved when uploading a new static
configuration. Work around this hardware oddity by reading its PTP time
before a static config upload, and restoring it afterwards.

Static config changes are expected to occur at runtime even in scenarios
directly related to PTP, i.e. the Time-Aware Scheduler of the switch is
programmed in this way.

Perhaps the larger implication of this patch is that the PTP .gettimex64
and .settime functions need to be exposed to sja1105_main.c, where the
PTP lock needs to be held during this entire process. So their core
implementation needs to move to some common functions which get exposed
in sja1105_ptp.h.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-11-11 12:45:30 -08:00
Vladimir Oltean
34d76e9fa8 net: dsa: sja1105: Implement the .gettimex64 system call for PTP
Through the PTP_SYS_OFFSET_EXTENDED ioctl, it is possible for userspace
applications (i.e. phc2sys) to compensate for the delays incurred while
reading the PHC's time.

The task itself of taking the software timestamp is delegated to the SPI
subsystem, through the newly introduced API in struct spi_transfer. The
goal is to cross-timestamp I/O operations on the switch's PTP clock with
values in the local system clock (CLOCK_REALTIME). For that we need to
understand a bit of the hardware internals.

The 'read PTP time' message is a 12 byte structure, first 4 bytes of
which represent the SPI header, and the last 8 bytes represent the
64-bit PTP time. The switch itself starts processing the command
immediately after receiving the last bit of the address, i.e. at the
middle of byte 3 (last byte of header). The PTP time is shadowed to a
buffer register in the switch, and retrieved atomically during the
subsequent SPI frames.

A similar thing goes on for the 'write PTP time' message, although in
that case the switch waits until the 64-bit PTP time becomes fully
available before taking any action. So the byte that needs to be
software-timestamped is byte 11 (last) of the transfer.

The patch creates a common (and local) sja1105_xfer implementation for
the SPI I/O, and offers 3 front-ends:

- sja1105_xfer_u32 and sja1105_xfer_u64: these are capable of optionally
  requesting a PTP timestamp

- sja1105_xfer_buf: this is for large transfers (e.g. the static config
  buffer) and other misc data, and there is no point in giving
  timestamping capabilities to this.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-11-11 12:45:30 -08:00
Andrew Lunn
0c65b2b90d net: of_get_phy_mode: Change API to solve int/unit warnings
Before this change of_get_phy_mode() returned an enum,
phy_interface_t. On error, -ENODEV etc, is returned. If the result of
the function is stored in a variable of type phy_interface_t, and the
compiler has decided to represent this as an unsigned int, comparision
with -ENODEV etc, is a signed vs unsigned comparision.

Fix this problem by changing the API. Make the function return an
error, or 0 on success, and pass a pointer, of type phy_interface_t,
where the phy mode should be stored.

v2:
Return with *interface set to PHY_INTERFACE_MODE_NA on error.
Add error checks to all users of of_get_phy_mode()
Fixup a few reverse christmas tree errors
Fixup a few slightly malformed reverse christmas trees

v3:
Fix 0-day reported errors.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-11-04 11:21:25 -08:00
David S. Miller
d31e95585c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
The only slightly tricky merge conflict was the netdevsim because the
mutex locking fix overlapped a lot of driver reload reorganization.

The rest were (relatively) trivial in nature.

Signed-off-by: David S. Miller <davem@davemloft.net>
2019-11-02 13:54:56 -07:00
Arnd Bergmann
5d294fc483 net: dsa: sja1105: improve NET_DSA_SJA1105_TAS dependency
An earlier bugfix introduced a dependency on CONFIG_NET_SCH_TAPRIO,
but this missed the case of NET_SCH_TAPRIO=m and NET_DSA_SJA1105=y,
which still causes a link error:

drivers/net/dsa/sja1105/sja1105_tas.o: In function `sja1105_setup_tc_taprio':
sja1105_tas.c:(.text+0x5c): undefined reference to `taprio_offload_free'
sja1105_tas.c:(.text+0x3b4): undefined reference to `taprio_offload_get'
drivers/net/dsa/sja1105/sja1105_tas.o: In function `sja1105_tas_teardown':
sja1105_tas.c:(.text+0x6ec): undefined reference to `taprio_offload_free'

Change the dependency to only allow selecting the TAS code when it
can link against the taprio code.

Fixes: a8d570de0c ("net: dsa: sja1105: Add dependency for NET_DSA_SJA1105_TAS")
Fixes: 317ab5b86c ("net: dsa: sja1105: Configure the Time-Aware Scheduler via tc-taprio offload")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-10-28 16:33:42 -07:00
Vivien Didelot
7e99e34701 net: dsa: remove dsa_switch_alloc helper
Now that ports are dynamically listed in the fabric, there is no need
to provide a special helper to allocate the dsa_switch structure. This
will give more flexibility to drivers to embed this structure as they
wish in their private structure.

Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
2019-10-22 12:37:07 -07:00
Vivien Didelot
d5a619bf60 net: dsa: sja1105: register switch before assigning port private data
Like the dsa_switch_tree structures, the dsa_port structures will be
allocated on switch registration.

The SJA1105 driver is the only one accessing the dsa_port structure
after the switch allocation and before the switch registration.
For that reason, move switch registration prior to assigning the priv
member of the dsa_port structures.

Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
2019-10-22 12:37:07 -07:00
Vivien Didelot
68bb8ea8ad net: dsa: use dsa_to_port helper everywhere
Do not let the drivers access the ds->ports static array directly
while there is a dsa_to_port helper for this purpose.

At the same time, un-const this helper since the SJA1105 driver
assigns the priv member of the returned dsa_port structure.

Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
2019-10-22 12:37:06 -07:00
David S. Miller
2f184393e0 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Several cases of overlapping changes which were for the most
part trivially resolvable.

Signed-off-by: David S. Miller <davem@davemloft.net>
2019-10-20 10:43:00 -07:00
Vladimir Oltean
2fb079a28a net: dsa: sja1105: Switch to hardware operations for PTP
Adjusting the hardware clock (PTPCLKVAL, PTPCLKADD, PTPCLKRATE) is a
requirement for the auxiliary PTP functionality of the switch
(TTEthernet, PPS input, PPS output).

Therefore we need to switch to using these registers to keep a
synchronized time in hardware, instead of the timecounter/cyclecounter
implementation, which is reliant on the free-running PTPTSCLK.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-10-18 12:55:30 -04:00
Nishad Kamdar
b790b5549b net: dsa: sja1105: Use the correct style for SPDX License Identifier
This patch corrects the SPDX License Identifier style
in header files related to Distributed Switch Architecture
drivers for NXP SJA1105 series Ethernet switch support.
It uses an expilict block comment for the SPDX License
Identifier.

Changes made by using a script provided by Joe Perches here:
https://lkml.org/lkml/2019/2/7/46.

Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Nishad Kamdar <nishadkamdar@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-10-15 20:16:26 -07:00
Vladimir Oltean
08839c06e9 net: dsa: sja1105: Switch to scatter/gather API for SPI
This reworks the SPI transfer implementation to make use of more of the
SPI core features. The main benefit is to avoid the memcpy in
sja1105_xfer_buf().

The memcpy was only needed because the function was transferring a
single buffer at a time. So it needed to copy the caller-provided buffer
at buf + 4, to store the SPI message header in the "headroom" area.

But the SPI core supports scatter-gather messages, comprised of multiple
transfers. We can actually use those to break apart every SPI message
into 2 transfers: one for the header and one for the actual payload.

To keep the behavior the same regarding the chip select signal, it is
necessary to tell the SPI core to de-assert the chip select after each
chunk. This was not needed before, because each spi_message contained
only 1 single transfer.

The meaning of the per-transfer cs_change=1 is:

- If the transfer is the last one of the message, keep CS asserted
- Otherwise, deassert CS

We need to deassert CS in the "otherwise" case, which was implicit
before.

Avoiding the memcpy creates yet another opportunity. The device can't
process more than 256 bytes of SPI payload at a time, so the
sja1105_xfer_long_buf() function used to exist, to split the larger
caller buffer into chunks.

But these chunks couldn't be used as scatter/gather buffers for
spi_message until now, because of that memcpy (we would have needed more
memory for each chunk). So we can now remove the sja1105_xfer_long_buf()
function and have a single implementation for long and short buffers.

Another benefit is lower usage of stack memory. Previously we had to
store 2 SPI buffers for each chunk. Due to the elimination of the
memcpy, we can now send pointers to the actual chunks from the
caller-supplied buffer to the SPI core.

Since the patch merges two functions into a rewritten implementation,
the function prototype was also changed, mainly for cosmetic consistency
with the structures used within it.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-10-15 13:16:57 -04:00
Vladimir Oltean
8a559400da net: dsa: sja1105: Move sja1105_spi_transfer into sja1105_xfer
This is a cosmetic patch that reduces some boilerplate in the SPI
interaction of the driver.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-10-15 13:16:56 -04:00
Vladimir Oltean
664277781c net: dsa: sja1105: Change the PTP command access pattern
The PTP command register contains enable bits for:
- Putting the 64-bit PTPCLKVAL register in add/subtract or write mode
- Taking timestamps off of the corrected vs free-running clock
- Starting/stopping the TTEthernet scheduling
- Starting/stopping PPS output
- Resetting the switch

When a command needs to be issued (e.g. "change the PTPCLKVAL from write
mode to add/subtract mode"), one cannot simply write to the command
register setting the PTPCLKADD bit to 1, because that would zeroize the
other settings. One also cannot do a read-modify-write (that would be
too easy for this hardware) because not all bits of the command register
are readable over SPI.

So this leaves us with the only option of keeping the value of the PTP
command register in the driver, and operating on that.

Actually there are 2 types of PTP operations now:
- Operations that modify the cached PTP command. These operate on
  ptp_data->cmd as a pointer.
- Operations that apply all previously cached PTP settings, but don't
  otherwise cache what they did themselves. The sja1105_ptp_reset
  function is such an example. It copies the ptp_data->cmd on stack
  before modifying and writing it to SPI.

This practically means that struct sja1105_ptp_cmd is no longer an
implementation detail, since it needs to be stored in full into struct
sja1105_ptp_data, and hence in struct sja1105_private. So the (*ptp_cmd)
function prototype can change and take struct sja1105_ptp_cmd as second
argument now.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-10-14 16:45:40 -07:00