In devices where the U-Boot is used as a secondary bootloader, we rely on the device's primary bootloader to implement CNTFRQ_EL0. However, this reliance may lead to a non-functional timer in broken firmware.
For instance, some versions of Samsung's S-Boot don't implement it. It's also not possible to set it in the U-Boot, because it's booted in a lower exception level. CNTFRQ_EL0 is reported to be 0. Use gd->arch.timer_rate_hz to override the queried value if set. This setting needs to be done in the board file, preferrably in timer_init(). Signed-off-by: Kaustabh Chakraborty <[email protected]> --- Changes in v2: - Switched to using gd->arch.timer_rate_hz instead of a new config option (Ahmad Fatoum) - Link to v1: https://lore.kernel.org/r/[email protected] --- arch/arm/cpu/armv8/generic_timer.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/arm/cpu/armv8/generic_timer.c b/arch/arm/cpu/armv8/generic_timer.c index 1de7ec596fc7cbbc3e78a241f163bc0a4fcad6b6..1bc72ed26ca31af8e8e72008ed7885cbde23b076 100644 --- a/arch/arm/cpu/armv8/generic_timer.c +++ b/arch/arm/cpu/armv8/generic_timer.c @@ -19,6 +19,10 @@ DECLARE_GLOBAL_DATA_PTR; unsigned long notrace get_tbclk(void) { unsigned long cntfrq; + + if (gd->arch.timer_rate_hz) + return gd->arch.timer_rate_hz; + asm volatile("mrs %0, cntfrq_el0" : "=r" (cntfrq)); return cntfrq; } --- base-commit: 582a04763aa80738c1c8ac60c47d1a5159a42833 change-id: 20251014-armv8-broken-cntfrq-f350f68fbf6e Best regards, -- Kaustabh Chakraborty <[email protected]>
