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45dfa45f52
Add support for hardware timestamps, if the firmware includes it as a feature via the GS_CAN_FEATURE_HW_TIMESTAMP flag. Check for this feature during probe, extend the RX expected length if it is and enable it during open. The struct classic_can_ts and struct canfd_ts are extended to include the µs timestamp following data as defined in the firmware. The timestamp is then captured and set using skb_hwtstamps() on each RX and TX. The frame µs timestamp is provided from a 32 bit 1 MHz timer which rolls over every 4294 seconds, so a cyclecounter, timecounter, and delayed worker are used to convert the timer into a proper ns timestamp - same implementation as commitefd8d98dfb("can: mcp251xfd: add HW timestamp infrastructure"). Hardware timestamps are added to capabilities as commitb1f6b93e67("can: mcp251xfd: advertise timestamping capabilities and add ioctl support"). Signed-off-by: John Whittington <git@jbrengineering.co.uk> Link: https://github.com/candle-usb/candleLight_fw/issues/100 Link: https://lore.kernel.org/all/20220827221548.3291393-3-mkl@pengutronix.de Co-developed-by: Marc Kleine-Budde <mkl@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 Restructured Text 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.