Hello, I would like to upstream my timestamping patch for CTU CAN FD IP core, but I guess it won't be that easy, so this is only an RFC. I'm using the timecounter/cyclecounter structures as has been recommended (basically copied from the mcp251xfd). But the hard part here is passing information to the driver, because the timestaping counter width and frequency isn't defined in the IP core specs. So currently I take both the counter width and frequency from Device Tree. The frequency can be specified in the form of second clock in "clocks" property (which seems good to me, because then the timestamping clock would be initialized and managed automatically, in case the clock isn't the same as the main clock). Or directly in "ts-frequency" property. Counter bit width is specified in the "ts-bit-width" property. This means that PCI devices currently can't report timestamps (because Device Tree isn't used for PCI devices). Alternatively, I could use module parameters, but those are frowned upon. Module_param also uses static variables, which means one parameter would be shared across multiple ctucanfd devices, which isn't great either. This patch also introduces another Kconfig option: CAN_CTUCANFD_PLATFORM_ENABLE_HW_TIMESTAMPS to control whether timestamps are enabled by default. I've done this for cases when somebody would like to disable timestamping (be it for performance reasons or whatever). Seems to me better than having to run some script after startup which would disable timestamping. I don't know which tool does can do this (ethtool/ip-link?), but I guess it would require the .ndo_eth_ioctl callback in the driver. Looking forward to some comments/feedback. Thank you, yours sincerely, Matej Vasilevski
