can: error: add definitions for the different CAN error thresholds

Currently, drivers are using magic numbers to derive the CAN error
states from the error counter. Add three macro declarations to
remediate this.

For reference, the error-active, error-passive and bus-off are defined
in ISO 11898, section 12.1.4.2 "Error counting". Although ISO 11898
does not define error-warning state, this extra value is also commonly
used and is thus also added.

Link: https://lore.kernel.org/all/20220719143550.3681-13-mailhol.vincent@wanadoo.fr
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: add CAN_ERR_CNT flag to notify availability of error counter

Add a dedicated flag in uapi/linux/can/error.h to notify the userland
that fields data[6] and data[7] of the CAN error frame were
respectively populated with the tx and rx error counters.

For all driver tree-wide, set up this flags whenever needed.

Link: https://lore.kernel.org/all/20220719143550.3681-12-mailhol.vincent@wanadoo.fr
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: error: specify the values of data[5..7] of CAN error frames

Currently, data[5..7] of struct can_frame, when used as a CAN error
frame, are defined as being "controller specific". Device specific
behaviours are problematic because it prevents someone from writing
code which is portable between devices.

As a matter of fact, data[5] is never used, data[6] is always used to
report TX error counter and data[7] is always used to report RX error
counter. can-utils also relies on this.

This patch updates the comment in the uapi header to specify that
data[5] is reserved (and thus should not be used) and that data[6..7]
are used for error counters.

Fixes: 0d66548a10cb ("[CAN]: Add PF_CAN core module")
Link: https://lore.kernel.org/all/20220719143550.3681-11-mailhol.vincent@wanadoo.fr
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: don't use deprecated license identifiers

The "GPL-2.0" license identifier changed to "GPL-2.0-only" in SPDX v3.0.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

License cleanup: add SPDX license identifier to uapi header files with a license

Many user space API headers have licensing information, which is either
incomplete, badly formatted or just a shorthand for referring to the
license under which the file is supposed to be. This makes it hard for
compliance tools to determine the correct license.

Update these files with an SPDX license identifier. The identifier was
chosen based on the license information in the file.

GPL/LGPL licensed headers get the matching GPL/LGPL SPDX license
identifier with the added 'WITH Linux-syscall-note' exception, which is
the officially assigned exception identifier for the kernel syscall
exception:

NOTE! This copyright does *not* cover user programs that use kernel
services by normal system calls - this is merely considered normal use
of the kernel, and does *not* fall under the heading of "derived work".

This exception makes it possible to include GPL headers into non GPL
code, without confusing license compliance tools.

Headers which have either explicit dual licensing or are just licensed
under a non GPL license are updated with the corresponding SPDX
identifier and the GPLv2 with syscall exception identifier. The format
is:
((GPL-2.0 WITH Linux-syscall-note) OR SPDX-ID-OF-OTHER-LICENSE)

SPDX license identifiers are a legally binding shorthand, which can be
used instead of the full boiler plate text. The update does not remove
existing license information as this has to be done on a case by case
basis and the copyright holders might have to be consulted. This will
happen in a separate step.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne. See the previous patch in this series for the
methodology of how this patch was researched.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

can: dev: Consolidate and unify state change handling

The handling of can error states is different between platforms.
This is an attempt to correct that problem.

I've moved this handling into a generic function for changing the
error state. This ensures that error state changes are handled
the same way everywhere (where this function is used).

This new mechanism also adds reverse state transitioning in error
frames, i.e. the user will be notified through the socket interface
when the state goes down.

Signed-off-by: Andri Yngvason <andri.yngvason@marel.com>
Acked-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: unify identifiers to ensure unique include processing

Armin pointed me to the fact that the identifier which is used to ensure the
unique include processing in lunux/include/uapi/linux/can.h is CAN_H.
This clashed with his own source as includes from libraries and APIs should
use an underscore '_' at the identifier start.

This patch fixes the protection identifiers in all CAN relavant includes.

Reported-by: Armin Burchardt <armin@uni-bremen.de>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: add explicit copyrights to can headers

These files are copied to the source code of user space applications (in
this case can-utils) and so it makes sense to mention explicitly their
copyright. I added the terms of C code that was introduced in the same
commit as these headers.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Acked-by: Urs Thuermann <urs.thuermann@volkswagen.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

UAPI: (Scripted) Disintegrate include/linux/can

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>