From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:31666 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726147AbgGBQdn (ORCPT ); Thu, 2 Jul 2020 12:33:43 -0400 From: Pierre Morel Subject: [kvm-unit-tests PATCH v10 4/9] s390x: clock and delays calculations Date: Thu, 2 Jul 2020 18:31:15 +0200 Message-Id: <1593707480-23921-5-git-send-email-pmorel@linux.ibm.com> In-Reply-To: <1593707480-23921-1-git-send-email-pmorel@linux.ibm.com> References: <1593707480-23921-1-git-send-email-pmorel@linux.ibm.com> Sender: linux-s390-owner@vger.kernel.org List-ID: To: kvm@vger.kernel.org Cc: linux-s390@vger.kernel.org, frankja@linux.ibm.com, david@redhat.com, thuth@redhat.com, cohuck@redhat.com, drjones@redhat.com 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 Reviewed-by: Thomas Huth Acked-by: Cornelia Huck Reviewed-by: Janosch Frank --- lib/s390x/asm/time.h | 30 +++++++++++++++++++++++++++--- 1 file changed, 27 insertions(+), 3 deletions(-) diff --git a/lib/s390x/asm/time.h b/lib/s390x/asm/time.h index 1791380..7375aa2 100644 --- a/lib/s390x/asm/time.h +++ b/lib/s390x/asm/time.h @@ -13,14 +13,38 @@ #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 */ - return (clk >> (63 - 51)) / 1000; + return clk >> STCK_SHIFT_US; +} + +static inline uint64_t get_clock_ms(void) +{ + return get_clock_us() / 1000; +} + +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); } #endif -- 2.25.1