Re: [kvm-unit-tests PATCH v2 04/10] arm/arm64: add some delay routines

Andrew Jones
2016-06-06T17:48:36Z

On Mon, Jun 06, 2016 at 06:39:50PM +0100, Alex Bennée wrote:
>
> Andrew Jones <drjones@redhat.com> writes:
>
> > Allow a thread to wait some specified amount of time. Can
> > specify in cycles, usecs, and msecs.
>
> I wonder if delay() and mdelay() can be in common code with just the
> freq and count getting functions in specific code? I guess that would
> need a lib/arm-generic/ or some such?

I'll think about that.

>
> Otherwise:
>
> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

Thanks,
drew

>
> >
> > Signed-off-by: Andrew Jones <drjones@redhat.com>
> > ---
> > lib/arm/asm/processor.h | 19 +++++++++++++++++++
> > lib/arm/processor.c | 15 +++++++++++++++
> > lib/arm64/asm/processor.h | 19 +++++++++++++++++++
> > lib/arm64/processor.c | 15 +++++++++++++++
> > 4 files changed, 68 insertions(+)
> >
> > diff --git a/lib/arm/asm/processor.h b/lib/arm/asm/processor.h
> > index d2048f5f5f7e6..afc903ca7d4ab 100644
> > --- a/lib/arm/asm/processor.h
> > +++ b/lib/arm/asm/processor.h
> > @@ -5,7 +5,9 @@
> > *
> > * This work is licensed under the terms of the GNU LGPL, version 2.
> > */
> > +#include <libcflat.h>
> > #include <asm/ptrace.h>
> > +#include <asm/barrier.h>
> >
> > enum vector {
> > EXCPTN_RST,
> > @@ -51,4 +53,21 @@ extern int mpidr_to_cpu(unsigned long mpidr);
> > extern void start_usr(void (*func)(void *arg), void *arg, unsigned long sp_usr);
> > extern bool is_user(void);
> >
> > +static inline u64 get_cntvct(void)
> > +{
> > + u64 vct;
> > + isb();
> > + asm volatile("mrrc p15, 1, %Q0, %R0, c14" : "=r" (vct));
> > + return vct;
> > +}
> > +
> > +extern void delay(u64 cycles);
> > +extern void udelay(unsigned long usecs);
> > +
> > +static inline void mdelay(unsigned long msecs)
> > +{
> > + while (msecs--)
> > + udelay(1000);
> > +}
> > +
> > #endif /* _ASMARM_PROCESSOR_H_ */
> > diff --git a/lib/arm/processor.c b/lib/arm/processor.c
> > index 54fdb87ef0196..c2ee360df6884 100644
> > --- a/lib/arm/processor.c
> > +++ b/lib/arm/processor.c
> > @@ -9,6 +9,7 @@
> > #include <asm/ptrace.h>
> > #include <asm/processor.h>
> > #include <asm/thread_info.h>
> > +#include <asm/barrier.h>
> >
> > static const char *processor_modes[] = {
> > "USER_26", "FIQ_26" , "IRQ_26" , "SVC_26" ,
> > @@ -141,3 +142,17 @@ bool is_user(void)
> > {
> > return current_thread_info()->flags & TIF_USER_MODE;
> > }
> > +
> > +void delay(u64 cycles)
> > +{
> > + u64 start = get_cntvct();
> > + while ((get_cntvct() - start) < cycles)
> > + cpu_relax();
> > +}
> > +
> > +void udelay(unsigned long usec)
> > +{
> > + unsigned int frq;
> > + asm volatile("mrc p15, 0, %0, c14, c0, 0" : "=r" (frq));
> > + delay((u64)usec * frq / 1000000);
> > +}
> > diff --git a/lib/arm64/asm/processor.h b/lib/arm64/asm/processor.h
> > index 7e448dc81a6aa..94f7ce35b65c1 100644
> > --- a/lib/arm64/asm/processor.h
> > +++ b/lib/arm64/asm/processor.h
> > @@ -17,8 +17,10 @@
> > #define SCTLR_EL1_M (1 << 0)
> >
> > #ifndef __ASSEMBLY__
> > +#include <libcflat.h>
> > #include <asm/ptrace.h>
> > #include <asm/esr.h>
> > +#include <asm/barrier.h>
> >
> > enum vector {
> > EL1T_SYNC,
> > @@ -89,5 +91,22 @@ extern int mpidr_to_cpu(unsigned long mpidr);
> > extern void start_usr(void (*func)(void *arg), void *arg, unsigned long sp_usr);
> > extern bool is_user(void);
> >
> > +static inline u64 get_cntvct(void)
> > +{
> > + u64 vct;
> > + isb();
> > + asm volatile("mrs %0, cntvct_el0" : "=r" (vct));
> > + return vct;
> > +}
> > +
> > +extern void delay(u64 cycles);
> > +extern void udelay(unsigned long usecs);
> > +
> > +static inline void mdelay(unsigned long msecs)
> > +{
> > + while (msecs--)
> > + udelay(1000);
> > +}
> > +
> > #endif /* !__ASSEMBLY__ */
> > #endif /* _ASMARM64_PROCESSOR_H_ */
> > diff --git a/lib/arm64/processor.c b/lib/arm64/processor.c
> > index deeab4ec9c8ac..50fa835c6f1e3 100644
> > --- a/lib/arm64/processor.c
> > +++ b/lib/arm64/processor.c
> > @@ -9,6 +9,7 @@
> > #include <asm/ptrace.h>
> > #include <asm/processor.h>
> > #include <asm/thread_info.h>
> > +#include <asm/barrier.h>
> >
> > static const char *vector_names[] = {
> > "el1t_sync",
> > @@ -253,3 +254,17 @@ bool is_user(void)
> > {
> > return current_thread_info()->flags & TIF_USER_MODE;
> > }
> > +
> > +void delay(u64 cycles)
> > +{
> > + u64 start = get_cntvct();
> > + while ((get_cntvct() - start) < cycles)
> > + cpu_relax();
> > +}
> > +
> > +void udelay(unsigned long usec)
> > +{
> > + unsigned int frq;
> > + asm volatile("mrs %0, cntfrq_el0" : "=r" (frq));
> > + delay((u64)usec * frq / 1000000);
> > +}
>
>
> --
> Alex Bennée
> --
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