From: Pierre Morel <pmorel@linux.ibm.com>
To: Cornelia Huck <cohuck@redhat.com>
Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org,
frankja@linux.ibm.com, david@redhat.com, thuth@redhat.com
Subject: Re: [kvm-unit-tests PATCH v9 06/12] s390x: clock and delays caluculations
Date: Wed, 17 Jun 2020 13:04:52 +0200 [thread overview]
Message-ID: <89cdae3e-1f50-03c1-e8ef-1f6b87a22fa9@linux.ibm.com> (raw)
In-Reply-To: <20200617102704.7755e11a.cohuck@redhat.com>
On 2020-06-17 10:27, Cornelia Huck wrote:
> On Mon, 15 Jun 2020 11:31:55 +0200
> Pierre Morel <pmorel@linux.ibm.com> wrote:
>
>> The hardware gives us a good definition of the microsecond,
>> let's keep this information and let the routine accessing
>> the hardware keep all the information and return microseconds.
>>
>> Calculate delays in microseconds and take care about wrapping
>> around zero.
>>
>> Define values with macros and use inlines to keep the
>> milliseconds interface.
>>
>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>> ---
>> lib/s390x/asm/time.h | 29 +++++++++++++++++++++++++++--
>> 1 file changed, 27 insertions(+), 2 deletions(-)
>>
>> diff --git a/lib/s390x/asm/time.h b/lib/s390x/asm/time.h
>> index 1791380..7f1d891 100644
>> --- a/lib/s390x/asm/time.h
>> +++ b/lib/s390x/asm/time.h
>> @@ -13,14 +13,39 @@
>> #ifndef ASM_S390X_TIME_H
>> #define ASM_S390X_TIME_H
>>
>> -static inline uint64_t get_clock_ms(void)
>> +#define STCK_SHIFT_US (63 - 51)
>> +#define STCK_MAX ((1UL << 52) - 1)
>> +
>> +static inline uint64_t get_clock_us(void)
>> {
>> uint64_t clk;
>>
>> asm volatile(" stck %0 " : : "Q"(clk) : "memory");
>>
>> /* Bit 51 is incrememented each microsecond */
>
> That comment may now be a tad non-obvious, because the details are
> hidden behind the #define? Anyway, no strong opinion.
You are right.
I find the macro's name is explicit so I remove the comment.
>
>> - return (clk >> (63 - 51)) / 1000;
>> + return clk >> STCK_SHIFT_US;
>> +}
>> +
>> +static inline void udelay(unsigned long us)
>> +{
>> + unsigned long startclk = get_clock_us();
>> + unsigned long c;
>> +
>> + do {
>> + c = get_clock_us();
>> + if (c < startclk)
>> + c += STCK_MAX;
>> + } while (c < startclk + us);
>> +}
>> +
>> +static inline void mdelay(unsigned long ms)
>> +{
>> + udelay(ms * 1000);
>> +}
>> +
>> +static inline uint64_t get_clock_ms(void)
>> +{
>> + return get_clock_us() / 1000;
>> }
>>
>> #endif
>
> Acked-by: Cornelia Huck <cohuck@redhat.com>
>
Thanks,
Pierre
--
Pierre Morel
IBM Lab Boeblingen
next prev parent reply other threads:[~2020-06-17 11:05 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-15 9:31 [kvm-unit-tests PATCH v9 00/12] s390x: Testing the Channel Subsystem I/O Pierre Morel
2020-06-15 9:31 ` [kvm-unit-tests PATCH v9 01/12] s390x: Use PSW bits definitions in cstart Pierre Morel
2020-06-16 9:31 ` Thomas Huth
2020-06-16 9:39 ` Pierre Morel
2020-06-16 13:13 ` Thomas Huth
2020-06-16 13:58 ` Pierre Morel
2020-06-16 14:01 ` Pierre Morel
2020-06-16 15:14 ` Thomas Huth
2020-06-16 16:08 ` Pierre Morel
2020-06-16 16:11 ` Pierre Morel
2020-06-15 9:31 ` [kvm-unit-tests PATCH v9 02/12] s390x: Move control register bit definitions and add AFP to them Pierre Morel
2020-06-15 9:31 ` [kvm-unit-tests PATCH v9 03/12] s390x: saving regs for interrupts Pierre Morel
2020-06-17 8:13 ` Cornelia Huck
2020-06-15 9:31 ` [kvm-unit-tests PATCH v9 04/12] s390x: interrupt registration Pierre Morel
2020-06-17 8:20 ` Cornelia Huck
2020-06-17 11:01 ` Pierre Morel
2020-06-15 9:31 ` [kvm-unit-tests PATCH v9 05/12] s390x: export the clock get_clock_ms() utility Pierre Morel
2020-06-15 9:31 ` [kvm-unit-tests PATCH v9 06/12] s390x: clock and delays caluculations Pierre Morel
2020-06-16 9:35 ` Thomas Huth
2020-06-16 9:40 ` Pierre Morel
2020-06-17 8:27 ` Cornelia Huck
2020-06-17 11:04 ` Pierre Morel [this message]
2020-06-22 9:09 ` Janosch Frank
2020-06-30 16:13 ` Pierre Morel
2020-06-15 9:31 ` [kvm-unit-tests PATCH v9 07/12] s390x: define function to wait for interrupt Pierre Morel
2020-06-15 9:31 ` [kvm-unit-tests PATCH v9 08/12] s390x: retrieve decimal and hexadecimal kernel parameters Pierre Morel
2020-06-16 9:47 ` Thomas Huth
2020-06-16 13:43 ` Pierre Morel
2020-06-17 8:37 ` Cornelia Huck
2020-06-17 11:05 ` Pierre Morel
2020-06-22 9:33 ` Janosch Frank
2020-06-22 10:57 ` Andrew Jones
2020-07-02 12:53 ` Pierre Morel
2020-06-15 9:31 ` [kvm-unit-tests PATCH v9 09/12] s390x: Library resources for CSS tests Pierre Morel
2020-06-16 10:31 ` Thomas Huth
2020-06-16 13:42 ` Pierre Morel
2020-06-17 8:42 ` Cornelia Huck
2020-06-17 11:08 ` Pierre Morel
2020-06-22 9:35 ` Janosch Frank
2020-06-24 12:26 ` Thomas Huth
2020-06-30 16:30 ` Pierre Morel
2020-06-15 9:31 ` [kvm-unit-tests PATCH v9 10/12] s390x: css: stsch, enumeration test Pierre Morel
2020-06-16 11:37 ` Thomas Huth
2020-06-16 13:42 ` Pierre Morel
2020-06-17 8:48 ` Cornelia Huck
2020-06-17 11:14 ` Pierre Morel
2020-06-15 9:32 ` [kvm-unit-tests PATCH v9 11/12] s390x: css: msch, enable test Pierre Morel
2020-06-16 11:43 ` Thomas Huth
2020-06-16 13:43 ` Pierre Morel
2020-06-17 8:54 ` Cornelia Huck
2020-06-17 11:25 ` Pierre Morel
2020-06-15 9:32 ` [kvm-unit-tests PATCH v9 12/12] s390x: css: ssch/tsch with sense and interrupt Pierre Morel
2020-06-17 9:54 ` Cornelia Huck
2020-06-17 11:55 ` Pierre Morel
2020-06-19 6:57 ` Cornelia Huck
2020-07-02 12:56 ` Pierre Morel
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