tree 4cf62782e85314f142695eb4792cb756d5f35a07
parent b0a8eabbf4d32d789686c32809750f95986dc7cb
author Michael Brown <mcb30@ipxe.org> 1730123291 +0000
committer Michael Brown <mcb30@ipxe.org> 1730123736 +0000

[riscv] Add support for RDTIME as a timer source

The Zicntr extension defines an unprivileged wall-clock time CSR that
roughly matches the behaviour of an invariant TSC on x86.  The nominal
frequency of this timer may be read from the "timebase-frequency"
property of the CPU node in the device tree.

Add a timer source using RDTIME to provide implementations of udelay()
and currticks(), modelled on the existing RDTSC-based timer for x86.

Signed-off-by: Michael Brown <mcb30@ipxe.org>