The mac statistics add pause/pfc durations in device version V3, we can
get total active cycle of pause/pfc from these durations.

As driver gets register number from firmware to calculate desc number to
query mac statistics, it needs to set mac statistics extended enable bit
in firmware command 0x701A to tell firmware that driver supports extended
mac statistics, otherwise firmware only returns register number of
version V1.

As pause/pfc durations are not supported by hardware of old version, they
should not been shown in command "ethtool -S ethX" in this case, so add
checking max register number of each mac statistic in their version.
If the max register number of one mac statistic is greater than register
number got from firmware, it means hardware does not support this mac
statistic, so ignore this statistic when get string and data of mac
statistic.
Signed-off-by: NGuangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently, driver queries number of mac statistics before querying mac
statistics. As the number of mac statistics is a fixed value in firmware,
it is redundant to query this number everytime before querying mac
statistics, it can just be queried once in initialization process and
saved in device specifications.
Signed-off-by: NGuangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

After querying mac statistics from firmware, driver copies data from
descriptors to struct mac_stats of hdev, and the number of copied data
is just according to the register number queried from firmware. There is
a problem that if the register number queried from firmware is larger
than data number of struct mac_stats, it will cause a copy overflow.

So if the firmware adds more mac statistics in later version, it is not
compatible with driver of old version.

To fix this problem, the number of copied data needs to be used the
minimum value between the register number queried from firmware and
data number of struct mac_stats.

The first descriptor has three data and there is one reserved, to
optimize the copy process, add this reserverd data to struct mac_stats.
Signed-off-by: NGuangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Since user may need to check the current configuration of the
interrupt coalesce, so add debugfs support for query this info.

Create a single file "coalesce_info" for it, and query it by
"cat coalesce_info", return the result to userspace.

For device whose version is above V3(include V3), the GL's register
contains usecs and 1us unit configuration. When get the usecs
configuration from this register, it will include the confusing unit
configuration, so add a GL mask to get the correct value, and add
a QL mask for the frames configuration as well.

The display style is below:
$ cat coalesce_info
tx interrupt coalesce info:
VEC_ID  ALGO_STATE  PROFILE_ID  CQE_MODE  TUNE_STATE  STEPS_LEFT...
0       IN_PROG     4           EQE       ON_TOP      0...
1       START       3           EQE       LEFT        1...

rx interrupt coalesce info:
VEC_ID  ALGO_STATE  PROFILE_ID  CQE_MODE  TUNE_STATE  STEPS_LEFT...
0       IN_PROG     3           EQE       LEFT        1...
1       IN_PROG     0           EQE       ON_TOP      0...
Signed-off-by: NHuazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: NGuangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Julian Wiedmann says:

====================
s390/qeth: updates 2021-10-25

please apply the following patch series for qeth to netdev's net-next tree.

This brings some minor maintenance improvements, and a bunch of cleanups
so that the W=1 build passes without warning.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

qeth_add_hw_header() is missing documentation for some of its
parameters, fix that up.
Reported-by: NHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: NJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fix kernel doc comments and remove incorrect kernel doc indicators.
Acked-by: NJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: NHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: NJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Allow the compiler to recognize and check format strings and parameters.

As reported with allmodconfig and W=1:

drivers/s390/net/qeth_core_main.c: In function ‘qeth_dbf_longtext’:
drivers/s390/net/qeth_core_main.c:6190:9: error: function ‘qeth_dbf_longtext’ might be a candidate for ‘gnu_printf’ format attribute [-Werror=suggest-attribute=format]
 6190 |         vsnprintf(dbf_txt_buf, sizeof(dbf_txt_buf), fmt, args);
      |         ^~~~~~~~~
Acked-by: NJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: NHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: NJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Various format strings don't match with types of parameters.
Fix all of them.
Acked-by: NJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: NHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: NJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The only actual user of qdio.no_input_queues is qeth_qdio_establish(),
and there we already have full awareness of the current Input Queue
configuration (1 RX queue, plus potentially 1 TX Completion queue).

So avoid this state tracking, and the ambiguity it brings with it.
Signed-off-by: NJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

For none of the users we are under risk of running in HW IRQ context or
or with IRQs disabled. Thus we always end up in consume_skb().

But the two occurences in the RX path should really report the dropped
packet to dropmon, so have them use kfree_skb() instead. That's also
consistent with what napi_free_frags() does internally.
Signed-off-by: NJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

qdio.ko no longer needs to care about how the QAOBs are allocated,
from its perspective they are merely another parameter to do_QDIO().

So for a start, shift the cache into the only qdio driver that uses
QAOBs (ie. qeth). Here there's further opportunity to optimize its
usage in the future - eg. make it per-{device, TX queue}, or only
compile it when the driver is built with CQ/QAOB support.
Signed-off-by: NJulian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: NBenjamin Block <bblock@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

With commit 18787eee ("qeth: use ndo_siocdevprivate") this callback
is now actually used to handle transport mode-specific _private_ ioctls.

We only have such ioctls for L3 devices. So wire up a L3-specific
.ndo_siocdevprivate() callback that handles those ioctls, and defers to
the core qeth_siocdevprivate() for all other private ioctls.

This takes the discipline one step closer to its original purpose of
providing an internal extension for the qeth_core_ccwgroup_driver.
Signed-off-by: NJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add the failed MAC address into the trace message. Also fix up one
format string to use %x instead of %u for the CARD_DEVID.
Signed-off-by: NJulian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: NAlexandra Winter <wintera@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Vladimir Oltean says:

====================
Drop rtnl_lock from DSA .port_fdb_{add,del}

As mentioned in the RFC posted 2 months ago:
https://patchwork.kernel.org/project/netdevbpf/cover/20210824114049.3814660-1-vladimir.oltean@nxp.com/

DSA is transitioning to a driver API where the rtnl_lock is not held
when calling ds->ops->port_fdb_add() and ds->ops->port_fdb_del().
Drivers cannot take that lock privately from those callbacks either.

This change is required so that DSA can wait for switchdev FDB work
items to finish before leaving the bridge. That change will be made in a
future patch series.

A small selftest is provided with the patch set in the hope that
concurrency issues uncovered by this series, but not spotted by me by
code inspection, will be caught.

A status of the existing drivers:

- mv88e6xxx_port_fdb_add() and mv88e6xxx_port_fdb_del() take
  mv88e6xxx_reg_lock() so they should be safe.

- qca8k_fdb_add() and qca8k_fdb_del() take mutex_lock(&priv->reg_mutex)
  so they should be safe.

- hellcreek_fdb_add() and hellcreek_fdb_add() take mutex_lock(&hellcreek->reg_lock)
  so they should be safe.

- ksz9477_port_fdb_add() and ksz9477_port_fdb_del() take mutex_lock(&dev->alu_mutex)
  so they should be safe.

- b53_fdb_add() and b53_fdb_del() did not have locking, so I've added a
  scheme based on my own judgement there (not tested).

- felix_fdb_add() and felix_fdb_del() did not have locking, I've added
  and tested a locking scheme there.

- mt7530_port_fdb_add() and mt7530_port_fdb_del() take
  mutex_lock(&priv->reg_mutex), so they should be safe.

- gswip_port_fdb() did not have locking, so I've added a non-expert
  locking scheme based on my own judgement (not tested).

- lan9303_alr_add_port() and lan9303_alr_del_port() take
  mutex_lock(&chip->alr_mutex) so they should be safe.

- sja1105_fdb_add() and sja1105_fdb_del() did not have locking, I've
  added and tested a locking scheme.

Changes in v3:
Unlock arl_mutex only once in b53_fdb_dump().

Changes in v4:
- Use __must_hold in ocelot and b53
- Add missing mutex_init in lantiq_gswip
- Clean up the selftest a bit.

Changes in v5:
- Replace __must_hold with a comment.
- Add a new patch (01/10).
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This test is a bit strange in that it is perhaps more manual than
others: it does not transmit a clear OK/FAIL verdict, because user space
does not have synchronous feedback from the kernel. If a hardware access
fails, it is in deferred context.

Nonetheless, on sja1105 I have used it successfully to find and solve a
concurrency issue, so it can be used as a starting point for other
driver maintainers too.
Signed-off-by: NVladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

These programs are useful, but not all selftests require them.

Additionally, on embedded boards without package management (things like
buildroot), installing mausezahn or jq is not always as trivial as
downloading a package from the web.

So it is actually a bit annoying to require programs that are not used.
Introduce options that can be set by scripts to not enforce these
dependencies. For compatibility, default to "yes".

Cc: Nikolay Aleksandrov <nikolay@nvidia.com>
Cc: Ido Schimmel <idosch@nvidia.com>
Cc: Guillaume Nault <gnault@redhat.com>
Cc: Po-Hsu Lin <po-hsu.lin@canonical.com>
Signed-off-by: NVladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Reviewed-by: NIdo Schimmel <idosch@nvidia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

After talking with Ido Schimmel, it became clear that rtnl_lock is not
actually required for anything that is done inside the
SWITCHDEV_FDB_{ADD,DEL}_TO_DEVICE deferred work handlers.

The reason why it was probably added by Arkadi Sharshevsky in commit
c9eb3e0f ("net: dsa: Add support for learning FDB through
notification") was to offer the same locking/serialization guarantees as
.ndo_fdb_{add,del} and avoid reworking any drivers.

DSA has implemented .ndo_fdb_add and .ndo_fdb_del until commit
b117e1e8 ("net: dsa: delete dsa_legacy_fdb_add and
dsa_legacy_fdb_del") - that is to say, until fairly recently.

But those methods have been deleted, so now we are free to drop the
rtnl_lock as well.

Note that exposing DSA switch drivers to an unlocked method which was
previously serialized by the rtnl_mutex is a potentially dangerous
affair. Driver writers couldn't ensure that their internal locking
scheme does the right thing even if they wanted.

We could err on the side of paranoia and introduce a switch-wide lock
inside the DSA framework, but that seems way overreaching. Instead, we
could check as many drivers for regressions as we can, fix those first,
then let this change go in once it is assumed to be fairly safe.
Signed-off-by: NVladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Now that the rtnl_mutex is going away for dsa_port_{host_,}fdb_{add,del},
no one is serializing access to the address lists that DSA keeps for the
purpose of reference counting on shared ports (CPU and cascade ports).

It can happen for one dsa_switch_do_fdb_del to do list_del on a dp->fdbs
element while another dsa_switch_do_fdb_{add,del} is traversing dp->fdbs.
We need to avoid that.

Currently dp->mdbs is not at risk, because dsa_switch_do_mdb_{add,del}
still runs under the rtnl_mutex. But it would be nice if it would not
depend on that being the case. So let's introduce a mutex per port (the
address lists are per port too) and share it between dp->mdbs and
dp->fdbs.

The place where we put the locking is interesting. It could be tempting
to put a DSA-level lock which still serializes calls to
.port_fdb_{add,del}, but it would still not avoid concurrency with other
driver code paths that are currently under rtnl_mutex (.port_fdb_dump,
.port_fast_age). So it would add a very false sense of security (and
adding a global switch-wide lock in DSA to resynchronize with the
rtnl_lock is also counterproductive and hard).

So the locking is intentionally done only where the dp->fdbs and dp->mdbs
lists are traversed. That means, from a driver perspective, that
.port_fdb_add will be called with the dp->addr_lists_lock mutex held on
the CPU port, but not held on user ports. This is done so that driver
writers are not encouraged to rely on any guarantee offered by
dp->addr_lists_lock.
Signed-off-by: NVladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The GSWIP switch accesses various bridging layer tables (VLANs, FDBs,
forwarding rules) indirectly through PCE registers. These hardware
accesses are non-atomic, being comprised of several register reads and
writes.

These accesses are currently serialized by the rtnl_lock, but DSA is
changing its driver API and that lock will no longer be held when
calling ->port_fdb_add() and ->port_fdb_del().

So this driver needs to serialize the access to the PCE registers using
its own locking scheme. This patch adds that.

Note that the driver also uses the gswip_pce_load_microcode() function
to load a static configuration for the packet classification engine into
a table using the same registers. It is currently not protected, but
since that configuration is only done from the dsa_switch_ops :: setup
method, there is no risk of it being concurrent with other operations.
Signed-off-by: NVladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: NHauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The b53 driver performs non-atomic transactions to the ARL table when
adding, deleting and reading FDB and MDB entries.

Traditionally these were all serialized by the rtnl_lock(), but now it
is possible that DSA calls ->port_fdb_add and ->port_fdb_del without
holding that lock.

So the driver must have its own serialization logic. Add a mutex and
hold it from all entry points (->port_fdb_{add,del,dump},
->port_mdb_{add,del}).
Signed-off-by: NVladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

DSA would like to remove the rtnl_lock from its
SWITCHDEV_FDB_{ADD,DEL}_TO_DEVICE handlers, and the felix driver uses
the same MAC table functions as ocelot.

This means that the MAC table functions will no longer be implicitly
serialized with respect to each other by the rtnl_mutex, we need to add
a dedicated lock in ocelot for the non-atomic operations of selecting a
MAC table row, reading/writing what we want and polling for completion.
Signed-off-by: NVladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The sja1105 hardware seems as concurrent as can be, but when we create a
background script that adds/removes a rain of FDB entries without the
rtnl_mutex taken, then in parallel we do another operation like run
'bridge fdb show', we can notice these errors popping up:

sja1105 spi2.0: port 2 failed to read back entry for 00:01:02:03:00:40 vid 0: -ENOENT
sja1105 spi2.0: port 2 failed to add 00:01:02:03:00:40 vid 0 to fdb: -2
sja1105 spi2.0: port 2 failed to read back entry for 00:01:02:03:00:46 vid 0: -ENOENT
sja1105 spi2.0: port 2 failed to add 00:01:02:03:00:46 vid 0 to fdb: -2

Luckily what is going on does not require a major rework in the driver.
The sja1105_dynamic_config_read() function sends multiple SPI buffers to
the peripheral until the operation completes. We should not do anything
until the hardware clears the VALID bit.

But since there is no locking (i.e. right now we are implicitly
serialized by the rtnl_mutex, but if we remove that), it might be
possible that the process which performs the dynamic config read is
preempted and another one performs a dynamic config write.

What will happen in that case is that sja1105_dynamic_config_read(),
when it resumes, expects to see VALIDENT set for the entry it reads
back. But it won't.

This can be corrected by introducing a mutex for serializing SPI
accesses to the dynamic config interface which should be atomic with
respect to each other.
Signed-off-by: NVladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The hardware manual says that software should attempt a new dynamic
config access (be it a a write or a read-back) only while the VALID bit
is cleared. The VALID bit is set by software to 1, and it remains set as
long as the hardware is still processing the request.

Currently the driver only polls for the command completion only for
reads, because that's when we need the actual data read back. Writes
have been more or less "asynchronous", although this has never been an
observable issue.

This change makes sja1105_dynamic_config_write poll the VALID bit as
well, to absolutely ensure that a follow-up access to the static config
finds the VALID bit cleared.

So VALID means "work in progress", while VALIDENT means "entry being
read is valid". On reads we check the VALIDENT bit too, while on writes
that bit is not always defined. So we need to factor it out of the loop,
and make the loop provide back the unpacked command structure, so that
sja1105_dynamic_config_read can check the VALIDENT bit.

The change also attempts to convert the open-coded loop to use the
read_poll_timeout macro, since I know this will come up during review.
It's more code, but hey, it uses read_poll_timeout!

Tested on SJA1105T, SJA1105S, SJA1110A.
Signed-off-by: NVladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

At present, when either of ds->ops->port_fdb_del() or ds->ops->port_mdb_del()
return a non-zero error code, we attempt to save the day and keep the
data structure associated with that switchdev object, as the deletion
procedure did not complete.

However, the way in which we do this is suspicious to the checker in
lib/refcount.c, who thinks it is buggy to increment a refcount that
became zero, and that this is indicative of a use-after-free.

Fixes: 161ca59d ("net: dsa: reference count the MDB entries at the cross-chip notifier level")
Signed-off-by: NVladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This reverts commit 965e6b26, reversing
changes made to 4d98bb0d.

Merge tag 'linux-can-next-for-5.16-20211024' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next

Marc Kleine-Budde says:

====================
pull-request: can-next 2021-10-24

this is a pull request of 15 patches for net-next/master.

The first patch is by Thomas Gleixner and makes use of
hrtimer_forward_now() in the CAN broad cast manager (bcm).

The next patch is by me and changes the type of the variables used in
the CAN bit timing calculation can_fixup_bittiming() to unsigned int.

Vincent Mailhol provides 6 patches targeting the CAN device
infrastructure. The CAN-FD specific Transmitter Delay Compensation
(TDC) is updated and configuration via the CAN netlink interface is
added.

Qing Wang's patch updates the at91 and janz-ican3 drivers to use
sysfs_emit() instead of snprintf() in the sysfs show functions.

Geert Uytterhoeven's patch drops the unneeded ARM dependency from the
rar Kconfig.

Cai Huoqing's patch converts the mscan driver to make use of the
dev_err_probe() helper function.

A patch by me against the gsusb driver changes the printf format
strings to use %u to print unsigned values.

Stephane Grosjean's patch updates the peak_usb CAN-FD driver to use
the 64 bit timestamps provided by the hardware.

The last 2 patches target the xilinx_can driver. Michal Simek provides
a patch that removes repeated word from the kernel-doc and Dongliang
Mu's patch removes a redundant netif_napi_del() from the xcan_remove()
function.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Since netif_napi_del() is already done in the free_candev(), we remove
this redundant netif_napi_del() invocation. In addition, this patch
can match the operations in the xcan_probe() and xcan_remove()
functions.

Link: https://lore.kernel.org/all/20211017125022.3100329-1-mudongliangabcd@gmail.comSigned-off-by: NDongliang Mu <mudongliangabcd@gmail.com>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

Trivial patch. Issue is reported by checkpatch.

Link: https://lore.kernel.org/all/267c11097c90debbb5b1efebbeabc98161177def.1632306843.git.michal.simek@xilinx.comSigned-off-by: NMichal Simek <michal.simek@xilinx.com>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

This patch allows to use the whole 64-bit timestamps received from the
CAN-FD device (expressed in µs) rather than only its low part, in the
hwtstamp structure of the skb transferred to the network layer, when a
CAN/CANFD frame has been received.

Link: https://lore.kernel.org/all/20210930094603.23134-1-s.grosjean@peak-system.comSigned-off-by: NStephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

This patch changes printf modifier to an unsigned int, as the printed
variables are unsigned.

Link: https://lore.kernel.org/all/20210914101005.84394-1-mkl@pengutronix.de
Cc: Roman Valls <brainstorm@nopcode.org>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

When possible use dev_err_probe help to properly deal with the
PROBE_DEFER error, the benefit is that DEFER issue will be logged
in the devices_deferred debugfs file.
And using dev_err_probe() can reduce code size, and simplify the code.

Link: https://lore.kernel.org/all/20210915145726.7092-1-caihuoqing@baidu.comSigned-off-by: NCai Huoqing <caihuoqing@baidu.com>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

The dependency on ARM predates the dependency on ARCH_RENESAS. The
latter was introduced for Renesas arm64 SoCs first, and later extended
to cover Renesas ARM SoCs, too.

Link: https://lore.kernel.org/all/362d9ced19f3524ee8917df5681b3880c13cac85.1630416373.git.geert+renesas@glider.beSigned-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

The sysfs show() functions must not use snprintf() when formatting the
value to be returned to user space.

Fix the following coccicheck warning:
| drivers/net/can/at91_can.c:1185: WARNING: use scnprintf or sprintf.
| drivers/net/can/janz-ican3.c:1834: WARNING: use scnprintf or sprintf.
|
| Use sysfs_emit instead of scnprintf or sprintf makes more sense.

Link: https://lore.kernel.org/all/1634280624-4816-1-git-send-email-wangqing@vivo.comSigned-off-by: NQing Wang <wangqing@vivo.com>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

struct can_tdc::tdco represents the absolute offset from TDCV. Some
controllers use instead an offset relative to the Sample Point (SP)
such that:
| SSP = TDCV + absolute TDCO
|     = TDCV + SP + relative TDCO

Consequently:
| relative TDCO = absolute TDCO - SP

The function can_tdc_get_relative_tdco() allow to retrieve this
relative TDCO value.

Link: https://lore.kernel.org/all/20210918095637.20108-7-mailhol.vincent@wanadoo.fr
CC: Stefan Mätje <Stefan.Maetje@esd.eu>
Signed-off-by: NVincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

Some CAN device can measure the TDCV (Transmission Delay Compensation
Value) automatically for each transmitted CAN frames.

A callback function do_get_auto_tdcv() is added to retrieve that
value. This function is used only if CAN_CTRLMODE_TDC_AUTO is enabled
(if CAN_CTRLMODE_TDC_MANUAL is selected, the TDCV value is provided by
the user).

If the device does not support reporting of TDCV, do_get_auto_tdcv()
should be set to NULL and TDCV will not be reported by the netlink
interface.

On success, do_get_auto_tdcv() shall return 0. If the value can not be
measured by the device, for example because network is down or because
no frames were transmitted yet, can_priv::do_get_auto_tdcv() shall
return a negative error code (e.g. -EINVAL) to signify that the value
is not yet available. In such cases, TDCV is not reported by the
netlink interface.

Link: https://lore.kernel.org/all/20210918095637.20108-6-mailhol.vincent@wanadoo.fr
CC: Stefan Mätje <stefan.maetje@esd.eu>
Signed-off-by: NVincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

Add the netlink interface for TDC parameters of struct can_tdc_const
and can_tdc.

Contrary to the can_bittiming(_const) structures for which there is
just a single IFLA_CAN(_DATA)_BITTMING(_CONST) entry per structure,
here, we create a nested entry IFLA_CAN_TDC. Within this nested entry,
additional IFLA_CAN_TDC_TDC* entries are added for each of the TDC
parameters of the newly introduced struct can_tdc_const and struct
can_tdc.

For struct can_tdc_const, these are:
        IFLA_CAN_TDC_TDCV_MIN
        IFLA_CAN_TDC_TDCV_MAX
        IFLA_CAN_TDC_TDCO_MIN
        IFLA_CAN_TDC_TDCO_MAX
        IFLA_CAN_TDC_TDCF_MIN
        IFLA_CAN_TDC_TDCF_MAX

For struct can_tdc, these are:
        IFLA_CAN_TDC_TDCV
        IFLA_CAN_TDC_TDCO
        IFLA_CAN_TDC_TDCF

This is done so that changes can be applied in the future to the
structures without breaking the netlink interface.

The TDC netlink logic works as follow:

 * CAN_CTRLMODE_FD is not provided:
    - if any TDC parameters are provided: error.

    - TDC parameters not provided: TDC parameters unchanged.

 * CAN_CTRLMODE_FD is provided and is false:
     - TDC is deactivated: both the structure and the
       CAN_CTRLMODE_TDC_{AUTO,MANUAL} flags are flushed.

 * CAN_CTRLMODE_FD provided and is true:
    - CAN_CTRLMODE_TDC_{AUTO,MANUAL} and tdc{v,o,f} not provided: call
      can_calc_tdco() to automatically decide whether TDC should be
      activated and, if so, set CAN_CTRLMODE_TDC_AUTO and uses the
      calculated tdco value.

    - CAN_CTRLMODE_TDC_AUTO and tdco provided: set
      CAN_CTRLMODE_TDC_AUTO and use the provided tdco value. Here,
      tdcv is illegal and tdcf is optional.

    - CAN_CTRLMODE_TDC_MANUAL and both of tdcv and tdco provided: set
      CAN_CTRLMODE_TDC_MANUAL and use the provided tdcv and tdco
      value. Here, tdcf is optional.

    - CAN_CTRLMODE_TDC_{AUTO,MANUAL} are mutually exclusive. Whenever
      one flag is turned on, the other will automatically be turned
      off. Providing both returns an error.

    - Combination other than the one listed above are illegal and will
      return an error.

N.B. above rules mean that whenever CAN_CTRLMODE_FD is provided, the
previous TDC values will be overwritten. The only option to reuse
previous TDC value is to not provide CAN_CTRLMODE_FD.

All the new parameters are defined as u32. This arbitrary choice is
done to mimic the other bittiming values with are also all of type
u32. An u16 would have been sufficient to hold the TDC values.

This patch completes below series (c.f. [1]):
  - commit 289ea9e4 ("can: add new CAN FD bittiming parameters:
    Transmitter Delay Compensation (TDC)")
  - commit c25cc799 ("can: bittiming: add calculation for CAN FD
    Transmitter Delay Compensation (TDC)")

[1] https://lore.kernel.org/linux-can/20210224002008.4158-1-mailhol.vincent@wanadoo.fr/T/#t

Link: https://lore.kernel.org/all/20210918095637.20108-5-mailhol.vincent@wanadoo.frSigned-off-by: NVincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

The function can_calc_tdco() directly retrieves can_priv from the
net_device and directly modifies it.

This is annoying for the upcoming patch. In
drivers/net/can/dev/netlink.c:can_changelink(), the data bittiming are
written to a temporary structure and memcpyed to can_priv only after
everything succeeded. In the next patch, where we will introduce the
netlink interface for TDC parameters, we will add a new TDC block
which can potentially fail. For this reason, the data bittiming
temporary structure has to be copied after that to-be-introduced TDC
block. However, TDC also needs to access data bittiming information.

We change the prototype so that the data bittiming structure is passed
to can_calc_tdco() as an argument instead of retrieving it from
priv. This way can_calc_tdco() can access the data bittiming before it
gets memcpyed to priv.

Link: https://lore.kernel.org/all/20210918095637.20108-4-mailhol.vincent@wanadoo.frSigned-off-by: NVincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

In the current implementation, all Transmission Delay Compensation
(TDC) parameters are expressed in time quantum. However, ISO 11898-1
actually specifies that these should be expressed in *minimum* time
quantum.

Furthermore, the minimum time quantum is specified to be "one node
clock period long" (c.f. paragraph 11.3.1.1 "Bit time"). For sake of
simplicity, we prefer to use the "clock period" term instead of
"minimum time quantum" because we believe that it is more broadly
understood.

This patch fixes that discrepancy by updating the documentation and
the formula for TDCO calculation.

N.B. In can_calc_tdco(), the sample point (in time quantum) was
calculated using a division, thus introducing a risk of rounding and
truncation errors. On top of changing the unit to clock period, we
also modified the formula to use only additions.

Link: https://lore.kernel.org/all/20210918095637.20108-3-mailhol.vincent@wanadoo.frSuggested-by: NStefan Mätje <Stefan.Maetje@esd.eu>
Signed-off-by: NVincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

ISO 11898-1 specifies in section 11.3.3 "Transmitter delay
compensation" that "the configuration range for [the] SSP position
shall be at least 0 to 63 minimum time quanta."

Because SSP = TDCV + TDCO, it means that we should allow both TDCV and
TDCO to hold zero value in order to honor SSP's minimum possible
value.

However, current implementation assigned special meaning to TDCV and
TDCO's zero values:
  * TDCV = 0 -> TDCV is automatically measured by the transceiver.
  * TDCO = 0 -> TDC is off.

In order to allow for those values to really be zero and to maintain
current features, we introduce two new flags:
  * CAN_CTRLMODE_TDC_AUTO indicates that the controller support
    automatic measurement of TDCV.
  * CAN_CTRLMODE_TDC_MANUAL indicates that the controller support
    manual configuration of TDCV. N.B.: current implementation failed
    to provide an option for the driver to indicate that only manual
    mode was supported.

TDC is disabled if both CAN_CTRLMODE_TDC_AUTO and
CAN_CTRLMODE_TDC_MANUAL flags are off, c.f. the helper function
can_tdc_is_enabled() which is also introduced in this patch.

Also, this patch adds three fields: tdcv_min, tdco_min and tdcf_min to
struct can_tdc_const. While we are not convinced that those three
fields could be anything else than zero, we can imagine that some
controllers might specify a lower bound on these. Thus, those minimums
are really added "just in case".

Comments of struct can_tdc and can_tdc_const are updated accordingly.

Finally, the changes are applied to the etas_es58x driver.

Link: https://lore.kernel.org/all/20210918095637.20108-2-mailhol.vincent@wanadoo.frSigned-off-by: NVincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>