Clocksource pointers can be problematic to obtain for drivers which are not clocksource drivers themselves. In particular, the RFC virtio_rtc driver [1] would require a new helper function to obtain a pointer to the Arm Generic Timer clocksource. The ptp_kvm driver also required a similar workaround. Add a clocksource ID member to struct system_counterval_t, which in the future shall identify the clocksource, and which shall replace the struct clocksource * member. By this, get_device_system_crosststamp() callers (such as virtio_rtc and ptp_kvm) will be able to supply easily accessible clocksource ids instead of clocksource pointers. [1] https://lore.kernel.org/lkml/20231218073849.35294-1-peter.hilber@xxxxxxxxxxxxxxx/ Signed-off-by: Peter Hilber <peter.hilber@xxxxxxxxxxxxxxx> --- Notes: v2: - Refer to clocksource IDs as such in comments (Thomas Gleixner). include/linux/timekeeping.h | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h index 7c43e98cf211..ca234fa4cc04 100644 --- a/include/linux/timekeeping.h +++ b/include/linux/timekeeping.h @@ -273,10 +273,15 @@ struct system_device_crosststamp { * @cycles: System counter value * @cs: Clocksource corresponding to system counter value. Used by * timekeeping code to verify comparibility of two cycle values + * @cs_id: Clocksource ID corresponding to system counter value. To be + * used instead of cs in the future. + * The default ID, CSID_GENERIC, does not identify a specific + * clocksource. */ struct system_counterval_t { u64 cycles; struct clocksource *cs; + enum clocksource_ids cs_id; }; /* -- 2.40.1
