v1-v4

Add davicom dm9051 spi ethernet driver. The driver work for the
device platform with spi master

Test ok with raspberry pi 2 and pi 4, the spi configure used in
my raspberry pi 4 is spi0.1, spi speed 31200000, and INT by pin 26.

v5

Work to eliminate the wrappers to be clear for read, swapped to
phylib for phy connection tasks.

Tested with raspberry pi 4. Test for netwroking function, CAT5
cable unplug/plug and also ethtool detect for link state, and
all are ok.

v6

remove the redundant code that phylib has support,
adjust to be the reasonable sequence,
fine tune comments, add comments for pause function support

Tested with raspberry pi 4. Test for netwroking function, CAT5
cable unplug/plug and also ethtool detect for link state, and
all are ok.

v7

read/write registers must return error code to the callet,
add to enable pause processing

v8

not parmanently set MAC by .ndo_set_mac_address

correct rx function such as clear ISR,
inblk avoid stack buffer,
simple skb buffer process and
easy use netif_rx_ni.

simplely queue init and wake the queues,
limit the start_xmit function use netif_stop_queue.

descript that schedule delay is essential
for tx_work and rxctrl_work

eliminate ____cacheline_aligned and
add static int msg_enable.

v9

use phylib, no need 'select MII' in Kconfig,
make it clear in dm9051_xfer when using spi_sync,
improve the registers read/write so that error code
return as far as possible up the call stack.

v10

use regmap APIs for SPI and MDIO,
modify to correcting such as include header files
and program check styles

v11

eliminate the redundant code for struct regmap_config data
use regmap_read_poll_timeout
use corresponding regmap APIs, i.e. MDIO, SPI
all read/write registers by regmap
all read/write registers with mutex lock by regmap
problem: regmap MDIO and SPI has no .reg_update_bits, I write it
in the driver
problem: this chip can support bulk read/write to rx/tx data, but
can not support bulk read/write to continue registers, so need
read/write register one by one

v12

correctly use regmap bulk read/write/update_bits APIs
use mdiobus to work to phylib and to this driver
fine tune to arrange the source code to better usage

This is a new yaml base data file for configure davicom dm9051 with
device tree

Cc: Rob Herring <robh@kernel.org>
Signed-off-by: JosephCHANG <josright123@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>

Use 2-factor multiplication argument form devm_kcalloc() instead
of devm_kzalloc().

Link: KSPP#162
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20211208040311.GA169838@embeddedor
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Use 2-factor multiplication argument form devm_kcalloc() instead
of devm_kzalloc().

Link: KSPP#162
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20211208003527.GA75483@embeddedor
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Antoine Tenart says:

====================
net: track the queue count at unregistration

Those two patches allow to track the Rx and Tx queue count at
unregistration and help in detecting illegal addition of Tx queues after
unregister (a warning is added).

This follows discussions on the following thread,
https://lore.kernel.org/all/20211122162007.303623-1-atenart@kernel.org/T/

A patch fixing one issue linked to this was merged ealier,
https://lore.kernel.org/all/20211203101318.435618-1-atenart@kernel.org/T/
====================

Link: https://lore.kernel.org/r/20211207145725.352657-1-atenart@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

…unregistration

Calling netdev_queue_update_kobjects is allowed during device
unregistration since commit 5c56580 ("net: Adjust TX queue kobjects
if number of queues changes during unregister"). But this is solely to
allow queue unregistrations. Any path attempting to add new queues after
a device started its unregistration should be fixed.

This patch adds a warning to detect such illegal use.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

When updating Rx and Tx queue kobjects, the queue count should always be
updated to match the queue kobjects count. This was not done in the net
device unregistration path, fix it. Tracking all queue count updates
will allow in a following up patch to detect illegal updates.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Sergey Ryazanov says:

====================
WWAN debugfs tweaks

This is a follow-up series to just applied IOSM (and WWAN) debugfs
interface support [1]. The series has two main goals:
1. move the driver-specific debugfs knobs to a subdirectory;
2. make the debugfs interface optional for both IOSM and for the WWAN
   core.

As for the first part, I must say that it was my mistake. I suggested to
place debugfs entries under a common per WWAN device directory. But I
missed the driver subdirectory in the example, so it become:

/sys/kernel/debugfs/wwan/wwan0/trace

Since the traces collection is a driver-specific feature, it is better
to keep it under the driver-specific subdirectory:

/sys/kernel/debugfs/wwan/wwan0/iosm/trace

It is desirable to be able to entirely disable the debugfs interface. It
can be disabled for several reasons, including security and consumed
storage space. See detailed rationale with usage example in the 4th
patch.

The changes themselves are relatively simple, but require a code
rearrangement. So to make changes clear, I chose to split them into
preparatory and main changes and properly describe each of them.

IOSM part is compile-tested only since I do not have IOSM supported
device, so it needs Ack from the driver developers.

I would like to thank Johannes Berg and Leon Romanovsky. Their
suggestions and comments helped a lot to rework the initial
over-engineered solution to something less confusing and much more
simple. Thanks!

1. https://lore.kernel.org/netdev/20211120162155.1216081-1-m.chetan.kumar@linux.intel.com
2. https://patchwork.kernel.org/project/netdevbpf/patch/20211204174033.950528-1-arnd@kernel.org/
====================

Link: https://lore.kernel.org/r/20211207092140.19142-1-ryazanov.s.a@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Debugfs interface is optional for the regular modem use. Some distros
and users will want to disable this feature for security or kernel
size reasons. So add a configuration option that allows to completely
disable the debugfs interface of the WWAN devices.

A primary considered use case for this option was embedded firmwares.
For example, in OpenWrt, you can not completely disable debugfs, as a
lot of wireless stuff can only be configured and monitored with the
debugfs knobs. At the same time, reducing the size of a kernel and
modules is an essential task in the world of embedded software.
Disabling the WWAN and IOSM debugfs interfaces allows us to save 50K
(x86-64 build) of space for module storage. Not much, but already
considerable when you only have 16MB of storage.

So it is hard to just disable whole debugfs. Users need some fine
grained set of options to control which debugfs interface is important
and should be available and which is not.

The new configuration symbol is enabled by default and is hidden under
the EXPERT option. So a regular user would not be bothered by another
one configuration question. While an embedded distro maintainer will be
able to a little more reduce the final image size.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Acked-by: M Chetan Kumar <m.chetan.kumar@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The modem traces collection is a device (and so driver) specific option.
Therefore, move the related debugfs files into a driver-specific
subdirectory under the common per WWAN device directory.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Acked-by: M Chetan Kumar <m.chetan.kumar@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Collecting modem firmware traces is optional for the regular modem use.
There are not many reasons for aborting device initialization due to an
inability to initialize the trace port and (or) its debugfs interface.
So, demote the initialization failure erro message into a warning and do
not break the initialization sequence in this case. Rework packet
processing and deinitialization so that they do not crash in case of
uninitialized trace port.

This change is mainly a preparation for an upcoming configuration option
introduction that will help disable driver debugfs functionality.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Acked-by: M Chetan Kumar <m.chetan.kumar@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Move the channel related structures initialization from
ipc_imem_channel_init() to ipc_trace_init() and call it directly. On the
one hand, this makes the trace port initialization symmetric to the
deitialization, that is, it removes the additional wrapper.

On the other hand, this change consolidates the trace port related code
into a single source file, what facilitates an upcoming disabling of
this functionality by a user choise.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Acked-by: M Chetan Kumar <m.chetan.kumar@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

…pub/scm/linux/kernel/git/mkl/linux-can-next

Marc Kleine-Budde says:

====================
can-next 2021-12-08

The first patch is by Vincent Mailhol and replaces the custom CAN
units with generic one form linux/units.h.

The next 3 patches are by Evgeny Boger and add Allwinner R40 support
to the sun4i CAN driver.

Andy Shevchenko contributes 4 patches to the hi311x CAN driver,
consisting of cleanups and converting the driver to the device
property API.

* tag 'linux-can-next-for-5.17-20211208' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next:
  can: hi311x: hi3110_can_probe(): convert to use dev_err_probe()
  can: hi311x: hi3110_can_probe(): make use of device property API
  can: hi311x: hi3110_can_probe(): try to get crystal clock rate from property
  can: hi311x: hi3110_can_probe(): use devm_clk_get_optional() to get the input clock
  ARM: dts: sun8i: r40: add node for CAN controller
  can: sun4i_can: add support for R40 CAN controller
  dt-bindings: net: can: add support for Allwinner R40 CAN controller
  can: bittiming: replace CAN units with the generic ones from linux/units.h
====================

Link: https://lore.kernel.org/r/20211208125055.223141-1-mkl@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Vladimir Oltean says:

====================
Rework DSA bridge TX forwarding offload API

This change set is preparation work for DSA support of bridge FDB
isolation. It replaces struct net_device *dp->bridge_dev with a struct
dsa_bridge *dp->bridge that contains some extra information about that
bridge, like a unique number kept by DSA.

Up until now we computed that number only with the bridge TX forwarding
offload feature, but it will be needed for other features too, like for
isolation of FDB entries belonging to different bridges. Hardware
implementations vary, but one common pattern seems to be the presence of
a FID field which can be associated with that bridge number kept by DSA.
The idea was outlined here:
https://patchwork.kernel.org/project/netdevbpf/patch/20210818120150.892647-16-vladimir.oltean@nxp.com/
(the difference being that with this new proposal, drivers would not
need to call dsa_bridge_num_find, instead the bridge_num would be part
of the struct dsa_bridge :: num passed as argument).

No functional change is intended for drivers that don't already make use
of the bridge TX forwarding offload. I've tested the changes on the
felix, sja1105 and mv88e6xxx drivers, but nonetheless I'm copying all
DSA driver maintainers due to API changes that are taking place.

Compared to v1 and v2, the amount of patches is larger, but the contents
is mostly the same, just split up hopefully a bit better for review.
====================

Link: https://lore.kernel.org/r/20211206165758.1553882-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

We don't really need new switch API for these, and with new switches
which intend to add support for this feature, it will become cumbersome
to maintain.

The change consists in restructuring the two drivers that implement this
offload (sja1105 and mv88e6xxx) such that the offload is enabled and
disabled from the ->port_bridge_{join,leave} methods instead of the old
->port_bridge_tx_fwd_{,un}offload.

The only non-trivial change is that mv88e6xxx_map_virtual_bridge_to_pvt()
has been moved to avoid a forward declaration, and the
mv88e6xxx_reg_lock() calls from inside it have been removed, since
locking is now done from mv88e6xxx_port_bridge_{join,leave}.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

This is a preparation patch for the removal of the DSA switch methods
->port_bridge_tx_fwd_offload() and ->port_bridge_tx_fwd_unoffload().
The plan is for the switch to report whether it offloads TX forwarding
directly as a response to the ->port_bridge_join() method.

This change deals with the noisy portion of converting all existing
function prototypes to take this new boolean pointer argument.
The bool is placed in the cross-chip notifier structure for bridge join,
and a reference to it is provided to drivers. In the next change, DSA
will then actually look at this value instead of calling
->port_bridge_tx_fwd_offload().

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

…cture

The main desire behind this is to provide coherent bridge information to
the fast path without locking.

For example, right now we set dp->bridge_dev and dp->bridge_num from
separate code paths, it is theoretically possible for a packet
transmission to read these two port properties consecutively and find a
bridge number which does not correspond with the bridge device.

Another desire is to start passing more complex bridge information to
dsa_switch_ops functions. For example, with FDB isolation, it is
expected that drivers will need to be passed the bridge which requested
an FDB/MDB entry to be offloaded, and along with that bridge_dev, the
associated bridge_num should be passed too, in case the driver might
want to implement an isolation scheme based on that number.

We already pass the {bridge_dev, bridge_num} pair to the TX forwarding
offload switch API, however we'd like to remove that and squash it into
the basic bridge join/leave API. So that means we need to pass this
pair to the bridge join/leave API.

During dsa_port_bridge_leave, first we unset dp->bridge_dev, then we
call the driver's .port_bridge_leave with what used to be our
dp->bridge_dev, but provided as an argument.

When bridge_dev and bridge_num get folded into a single structure, we
need to preserve this behavior in dsa_port_bridge_leave: we need a copy
of what used to be in dp->bridge.

Switch drivers check bridge membership by comparing dp->bridge_dev with
the provided bridge_dev, but now, if we provide the struct dsa_bridge as
a pointer, they cannot keep comparing dp->bridge to the provided
pointer, since this only points to an on-stack copy. To make this
obvious and prevent driver writers from forgetting and doing stupid
things, in this new API, the struct dsa_bridge is provided as a full
structure (not very large, contains an int and a pointer) instead of a
pointer. An explicit comparison function needs to be used to determine
bridge membership: dsa_port_offloads_bridge().

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Move the static inline helpers from net/dsa/dsa_priv.h to
include/net/dsa.h, so that drivers can call functions such as
dsa_port_offloads_bridge_dev(), which will be necessary after the
transition to a more complex bridge structure.

More functions than are needed right now are being moved, but this is
done for uniformity.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

…_dev

Currently the majority of dsa_port_bridge_dev_get() calls in drivers is
just to check whether a port is under the bridge device provided as
argument by the DSA API.

We'd like to change that DSA API so that a more complex structure is
provided as argument. To keep things more generic, and considering that
the new complex structure will be provided by value and not by
reference, direct comparisons between dp->bridge and the provided bridge
will be broken. The generic way to do the checking would simply be to
do something like dsa_port_offloads_bridge(dp, &bridge).

But there's a problem, we already have a function named that way, which
actually takes a bridge_dev net_device as argument. Rename it so that we
can use dsa_port_offloads_bridge for something else.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

…lpers

The location of the bridge device pointer and number is going to change.
It is not going to be kept individually per port, but in a common
structure allocated dynamically and which will have lockdep validation.

Use the helpers to access these elements so that we have a migration
path to the new organization.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

…elpers

The location of the bridge device pointer and number is going to change.
It is not going to be kept individually per port, but in a common
structure allocated dynamically and which will have lockdep validation.

Create helpers to access these elements so that we have a migration path
to the new organization.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

…_dev comparison

The goal of this change is to reduce mv88e6xxx_port_vlan() to a form
where dsa_port_bridge_same() can be used, since the dp->bridge_dev
pointer will be hidden in a future change.

To do that, we observe that the "br" pointer is deduced from a
dp->bridge_dev in both cases (of a physical switch port as well as a
virtual bridge). So instead of keeping the "br" pointer, we can just
keep the "dp" pointer from which "br" gets derived.

In the last iteration over switch ports, we must use another iterator
variable, "other_dp"since now we use the "dp" variable to keep an
indirect reference to the bridge. While at it, the old code used to
filter only the ports which were part of the same switch as "ds".
There exists a dedicated DSA port iterator for that:
dsa_switch_for_each_port (which skips the ports in the tree that belong
to non-local switches), so we can just use that.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

…v88e6xxx_port_check_hw_vlan

Avoid a plethora of dsa_to_port() calls (some hidden behind
dsa_is_*_port and some in plain sight) by keeping two struct dsa_port
references: one to the port passed as argument, and another to the other
ports of the switch that we're iterating over.

This isn't called from the DSA initialization path, so there is no risk
that we have user ports without a dp->slave populated. So the combined
checks that a port isn't a DSA port, a CPU port, or doesn't have a slave
net device (therefore is unused), are strictly equivalent to the simple
check that the port is a user port. This is already handled by the DSA
iterator.

i gets replaced by other_dp->index, dsa_is_*_port calls get replaced by
dsa_port_is_*, and dsa_to_port gets replaced by the respective pointer
directly.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

…ging ops

Avoid repeated calls to dsa_to_port() (some hidden behind dsa_is_user_port
and some in plain sight) by keeping two struct dsa_port references: one
to the port passed as argument, and another to the other ports of the
switch that we're iterating over.

dsa_to_port(ds, i) gets replaced by other_dp, i gets replaced by
other_port which is derived from other_dp->index, dsa_is_user_port is
handled by the DSA iterator.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The service where DSA assigns a unique bridge number for each forwarding
domain is useful even for drivers which do not implement the TX
forwarding offload feature.

For example, drivers might use the dp->bridge_num for FDB isolation.

So rename ds->num_fwd_offloading_bridges to ds->max_num_bridges, and
calculate a unique bridge_num for all drivers that set this value.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

I have seen too many bugs already due to the fact that we must encode an
invalid dp->bridge_num as a negative value, because the natural tendency
is to check that invalid value using (!dp->bridge_num). Latest example
can be seen in commit 1bec0f0 ("net: dsa: fix bridge_num not
getting cleared after ports leaving the bridge").

Convert the existing users to assume that dp->bridge_num == 0 is the
encoding for invalid, and valid bridge numbers start from 1.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

When deferred the reason is saved for further debugging. Besides that,
it's fine to call dev_err_probe() in ->probe() when error code is
known. Convert the driver to use dev_err_probe().

Link: https://lore.kernel.org/all/20211206165542.69887-4-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Make use of device property API in this driver so that both OF based
system and ACPI based system can use this driver.

Link: https://lore.kernel.org/all/20211206165542.69887-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

…roperty

In some configurations, mainly ACPI-based, the clock frequency of the
device is supplied by very well established 'clock-frequency'
property. Hence, try to get it from the property at last if no other
providers are available.

Link: https://lore.kernel.org/all/20211206165542.69887-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

…he input clock

It's not clear what was the intention of redundant usage of IS_ERR()
around the clock pointer since with the error check of devm_clk_get()
followed by bailout it can't be invalid,

Simplify the code which fetches the input clock by using
devm_clk_get_optional(). It will allow to switch to device properties
approach in the future.

Link: https://lore.kernel.org/all/20211206165542.69887-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Allwinner R40 (also known as A40i, T3, V40) has a CAN controller. The
controller is the same as in earlier A10 and A20 SoCs, but needs reset
line to be deasserted before use.

This patch adds a CAN node and the corresponding pinctrl descriptions.

Link: https://lore.kernel.org/all/20211122104616.537156-4-boger@wirenboard.com
Signed-off-by: Evgeny Boger <boger@wirenboard.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Allwinner R40 (also known as A40i, T3, V40) has a CAN controller. The
controller is the same as in earlier A10 and A20 SoCs, but needs reset
line to be deasserted before use.

This patch adds a new compatible for R40 CAN controller. Depending
on the compatible, reset line can be requested from DT.

Link: https://lore.kernel.org/all/20211122104616.537156-3-boger@wirenboard.com
Signed-off-by: Evgeny Boger <boger@wirenboard.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Allwinner R40 (also known as A40i, T3, V40) has a CAN controller. The
controller is the same as in earlier A10 and A20 SoCs, but needs reset
line to be deasserted before use.

This patch Introduces new compatible for R40 CAN controller with
required resets property.

Link: https://lore.kernel.org/all/20211122104616.537156-2-boger@wirenboard.com
Signed-off-by: Evgeny Boger <boger@wirenboard.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

…its.h

In [1], we introduced a set of units in linux/can/bittiming.h. Since
then, generic SI prefixes were added to linux/units.h in [2]. Those
new prefixes can perfectly replace CAN specific ones.

This patch replaces all occurrences of the CAN units with their
corresponding prefix (from linux/units) and the unit (as a comment)
according to below table.

 CAN units	SI metric prefix (from linux/units) + unit (as a comment)
 ------------------------------------------------------------------------
 CAN_KBPS	KILO /* BPS */
 CAN_MBPS	MEGA /* BPS */
 CAM_MHZ	MEGA /* Hz */

The definition are then removed from linux/can/bittiming.h

[1] commit 1d77507 ("can: bittiming: add CAN_KBPS, CAN_MBPS and
CAN_MHZ macros")

[2] commit 26471d4 ("units: Add SI metric prefix definitions")

Link: https://lore.kernel.org/all/20211124014536.782550-1-mailhol.vincent@wanadoo.fr
Suggested-by: Jimmy Assarsson <extja@kvaser.com>
Suggested-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Alexandra Winter says:

====================
s390/net: updates 2021-12-06

This brings some maintenance improvements and removes some
unnecessary code checks.
====================

Link: https://lore.kernel.org/r/20211207090452.1155688-1-wintera@linux.ibm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>