[PATCH v3] clocksource: arch_timer: Allow the device tree to specify the physical timer
cov at codeaurora.org
Mon Sep 29 06:12:26 PDT 2014
On 09/11/2014 01:00 PM, Doug Anderson wrote:
> Some 32-bit (ARMv7) systems are architected like this:
> * The firmware doesn't know and doesn't care about hypervisor mode and
> we don't want to add the complexity of hypervisor there.
> * The firmware isn't involved in SMP bringup or resume.
> * The ARCH timer come up with an uninitialized offset between the
> virtual and physical counters. Each core gets a different random
> * The device boots in "Secure SVC" mode.
I believe this can safely be detected by whether a write to CNTFRQ succeeds
(handling the UNDEF on failure). I've tested this approach in what I've
determined to be the 19 valid combinations of the following options.
* AArch64 EL3, AArch32 EL3, no EL3
* AArch64 EL2, AArch32 EL2, no EL2
* Start in SVC_N, SVC_S, HYP_N, MON_S
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by the Linux Foundation.
More information about the linux-arm-kernel