path: root/arch/arm64/include/asm
diff options
authorSonny Rao <sonnyrao@chromium.org>2014-11-23 23:02:44 -0800
committerOlof Johansson <olof@lixom.net>2014-12-04 23:30:26 -0800
commit0b46b8a718c6e90910a1b1b0fe797be3c167e186 (patch)
treeeca0d7cd13798df4bc81afe88f9686b9a3e1aaa6 /arch/arm64/include/asm
parentf114040e3ea6e07372334ade75d1ee0775c355e1 (diff)
clocksource: arch_timer: Fix code to use physical timers when requested
This is a bug fix for using physical arch timers when the arch_timer_use_virtual boolean is false. It restores the arch_counter_get_cntpct() function after removal in 0d651e4e "clocksource: arch_timer: use virtual counters" We need this on certain ARMv7 systems which 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 offset. * The device boots in "Secure SVC" mode. * Nothing has touched the reset value of CNTHCTL.PL1PCEN or CNTHCTL.PL1PCTEN (both default to 1 at reset) One example of such as system is RK3288 where it is much simpler to use the physical counter since there's nobody managing the offset and each time a core goes down and comes back up it will get reinitialized to some other random value. Fixes: 0d651e4e65e9 ("clocksource: arch_timer: use virtual counters") Cc: stable@vger.kernel.org Signed-off-by: Sonny Rao <sonnyrao@chromium.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by: Olof Johansson <olof@lixom.net>
Diffstat (limited to 'arch/arm64/include/asm')
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h
index f19097134b02..b1fa4e614718 100644
--- a/arch/arm64/include/asm/arch_timer.h
+++ b/arch/arm64/include/asm/arch_timer.h
@@ -104,6 +104,15 @@ static inline void arch_timer_set_cntkctl(u32 cntkctl)
asm volatile("msr cntkctl_el1, %0" : : "r" (cntkctl));
+static inline u64 arch_counter_get_cntpct(void)
+ /*
+ * AArch64 kernel and user space mandate the use of CNTVCT.
+ */
+ BUG();
+ return 0;
static inline u64 arch_counter_get_cntvct(void)
u64 cval;