mirror of
https://github.com/torvalds/linux.git
synced 2025-12-07 20:06:24 +00:00
113aa9101a
Marc Kleine-Budde <mkl@pengutronix.de> says: Similarly to how CAN FD reuses the bittiming logic of Classical CAN, CAN XL also reuses the entirety of CAN FD features, and, on top of that, adds new features which are specific to CAN XL. A so-called 'mixed-mode' is intended to have (XL-tolerant) CAN FD nodes and CAN XL nodes on one CAN segment, where the FD-controllers can talk CC/FD and the XL-controllers can talk CC/FD/XL. This mixed-mode utilizes the known error-signalling (ES) for sending CC/FD/XL frames. For CAN FD and CAN XL the tranceiver delay compensation (TDC) is supported to use common CAN and CAN-SIG transceivers. The CANXL-only mode disables the error-signalling in the CAN XL controller. This mode does not allow CC/FD frames to be sent but additionally offers a CAN XL transceiver mode switching (TMS) to send CAN XL frames with up to 20Mbit/s data rate. The TMS utilizes a PWM configuration which is added to the netlink interface. Configured with CAN_CTRLMODE_FD and CAN_CTRLMODE_XL this leads to: FD=0 XL=0 CC-only mode (ES=1) FD=1 XL=0 FD/CC mixed-mode (ES=1) FD=1 XL=1 XL/FD/CC mixed-mode (ES=1) FD=0 XL=1 XL-only mode (ES=0, TMS optional) Patch #1 print defined ctrlmode strings capitalized to increase the readability and to be in line with the 'ip' tool (iproute2). Patch #2 is a small clean-up which makes can_calc_bittiming() use NL_SET_ERR_MSG() instead of netdev_err(). Patch #3 adds a check in can_dev_dropped_skb() to drop CAN FD frames when CAN FD is turned off. Patch #4 adds CAN_CTRLMODE_RESTRICTED. Note that contrary to the other CAN_CTRL_MODE_XL_* that are introduced in the later patches, this control mode is not specific to CAN XL. The nuance is that because this restricted mode was only added in ISO 11898-1:2024, it is made mandatory for CAN XL devices but optional for other protocols. This is why this patch is added as a preparation before introducing the core CAN XL logic. Patch #5 adds all the CAN XL features which are inherited from CAN FD: the nominal bittiming, the data bittiming and the TDC. Patch #6 add a new CAN_CTRLMODE_XL_TMS control mode which is specific to CAN XL to enable the transceiver mode switching (TMS) in XL-only mode. Patch #7 adds a check in can_dev_dropped_skb() to drop CAN CC/FD frames when the CAN XL controller is in CAN XL-only mode. The introduced can_dev_in_xl_only_mode() function also determines the error-signalling configuration for the CAN XL controllers. Patch #8 to #11 add the PWM logic for the CAN XL TMS mode. Patch #12 to #14 add different default sample-points for standard CAN and CAN SIG transceivers (with TDC) and CAN XL transceivers using PWM in the CAN XL TMS mode. Patch #15 add a dummy_can driver for netlink testing and debugging. Patch #16 check CAN frame type (CC/FD/XL) when writing those frames to the CAN_RAW socket and reject them if it's not supported by the CAN interface. Patch #17 increase the resolution when printing the bitrate error and round-up the value to 0.01% in the case the resolution would still provide values which would lead to 0.00%. Link: https://patch.msgid.link/20251126-canxl-v8-0-e7e3eb74f889@pengutronix.de Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.