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From: Janosch Frank <frankja@linux.ibm.com>
To: pbonzini@redhat.com
Cc: kvm@vger.kernel.org, frankja@linux.vnet.ibm.com,
	david@redhat.com, thuth@redhat.com, pmorel@linux.ibm.com,
	linux-s390@vger.kernel.org, imbrenda@linux.ibm.com
Subject: [kvm-unit-tests GIT PULL 05/11] s390x: clock and delays calculations
Date: Fri, 31 Jul 2020 11:46:01 +0200
Message-ID: <20200731094607.15204-6-frankja@linux.ibm.com> (raw)
In-Reply-To: <20200731094607.15204-1-frankja@linux.ibm.com>

From: Pierre Morel <pmorel@linux.ibm.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 <pmorel@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Message-Id: <1594887809-10521-5-git-send-email-pmorel@linux.ibm.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 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
-- 
2.25.4


  parent reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-31  9:45 [kvm-unit-tests GIT PULL 00/11] s390x patches Janosch Frank
2020-07-31  9:45 ` [kvm-unit-tests GIT PULL 01/11] s390x/cpumodel: The missing DFP facility on TCG is expected Janosch Frank
2020-07-31  9:45 ` [kvm-unit-tests GIT PULL 02/11] s390x: saving regs for interrupts Janosch Frank
2020-07-31  9:45 ` [kvm-unit-tests GIT PULL 03/11] s390x: I/O interrupt registration Janosch Frank
2020-07-31  9:46 ` [kvm-unit-tests GIT PULL 04/11] s390x: export the clock get_clock_ms() utility Janosch Frank
2020-07-31  9:46 ` Janosch Frank [this message]
2020-07-31  9:46 ` [kvm-unit-tests GIT PULL 06/11] s390x: define function to wait for interrupt Janosch Frank
2020-07-31  9:46 ` [kvm-unit-tests GIT PULL 07/11] s390x: Library resources for CSS tests Janosch Frank
2020-07-31  9:46 ` [kvm-unit-tests GIT PULL 08/11] s390x: css: stsch, enumeration test Janosch Frank
2020-07-31  9:46 ` [kvm-unit-tests GIT PULL 09/11] s390x: css: msch, enable test Janosch Frank
2020-07-31  9:46 ` [kvm-unit-tests GIT PULL 10/11] s390x: css: ssch/tsch with sense and interrupt Janosch Frank
2020-07-31  9:46 ` [kvm-unit-tests GIT PULL 11/11] s390x: fix inline asm on gcc10 Janosch Frank
2020-07-31 10:31 ` [kvm-unit-tests GIT PULL 00/11] s390x patches Paolo Bonzini
2020-07-31 11:31   ` Janosch Frank
2020-07-31 12:09     ` Thomas Huth
2020-07-31 12:31       ` Janosch Frank

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