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

["Alex Bennée" <alex.bennee@linaro.org>]

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?

Otherwise:

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

>
> 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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