@@ -78,6 +78,15 @@ static inline u32 arch_timer_get_cntfrq(void)
return val;
}
+static inline u64 arch_counter_get_cntpct(void)
+{
+ u64 cval;
+
+ isb();
+ asm volatile("mrrc p15, 0, %Q0, %R0, c14" : "=r" (cval));
+ return cval;
+}
+
static inline u64 arch_counter_get_cntvct(void)
{
u64 cval;
@@ -135,6 +135,15 @@ static inline void arch_timer_evtstrm_enable(int divider)
#endif
}
+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;
@@ -430,7 +430,10 @@ static void __init arch_counter_register(unsigned type)
/* Register the CP15 based counter if we have one */
if (type & ARCH_CP15_TIMER) {
- arch_timer_read_counter = arch_counter_get_cntvct;
+ if (arch_timer_use_virtual)
+ arch_timer_read_counter = arch_counter_get_cntvct;
+ else
+ arch_timer_read_counter = arch_counter_get_cntpct;
} else {
arch_timer_read_counter = arch_counter_get_cntvct_mem;
This is a note to let you know that I have just added a patch titled clocksource: arch_timer: Fix code to use physical timers when requested to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue This patch is scheduled to be released in version 3.16.7-ckt4. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.16.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 55b3b66e6ed349b3a28f3a5da0c373d08cae6e64 Mon Sep 17 00:00:00 2001 From: Sonny Rao <sonnyrao@chromium.org> Date: Sun, 23 Nov 2014 23:02:44 -0800 Subject: clocksource: arch_timer: Fix code to use physical timers when requested commit 0b46b8a718c6e90910a1b1b0fe797be3c167e186 upstream. 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") 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> [ luis: backported to 3.16: adjusted context ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- arch/arm/include/asm/arch_timer.h | 9 +++++++++ arch/arm64/include/asm/arch_timer.h | 9 +++++++++ drivers/clocksource/arm_arch_timer.c | 5 ++++- 3 files changed, 22 insertions(+), 1 deletion(-) -- 2.1.4