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Staging: hv: Integrate the time source driver with Hyper-V detection code

PATCH In review K. Y. Srinivasan 2 participants 2 messages Sep 7, 2011 – Sep 9, 2011

Subsystems (4)
x86 Staging virtio core Hyper-V/Azure core and drivers
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K. Y. Srinivasan

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PATCH 1/1 Staging: hv: Integrate the time source driver with Hyper-V detection code

The Hyper-V timesource driver is best integrated with Hyper-V detection code
since: (a) Linux guests running on Hyper-V need this timesource and (b) by integrating with Hyper-V detection, we could significantly minimize the code in the timesource driver.

Signed-off-by K. Y. Srinivasan <[email protected]>
Signed-off-by Haiyang Zhang <[email protected]>
---
 arch/x86/kernel/cpu/mshyperv.c     |   24 +++++++++
 drivers/staging/hv/Makefile        |    2 +-
 drivers/staging/hv/hv_timesource.c |  101 ------------------------------------
 3 files changed, 25 insertions(+), 102 deletions(-)
 delete mode 100644 drivers/staging/hv/hv_timesource.c
arch/x86/kernel/cpu/mshyperv.c +24 -0
index d944bf6..c97f88d 100644
@@ -11,6 +11,8 @@
  */
 
 #include <linux/types.h>
+#include <linux/time.h>
+#include <linux/clocksource.h>
 #include <linux/module.h>
 #include <asm/processor.h>
 #include <asm/hypervisor.h>

@@ -36,6 +38,25 @@ static bool __init ms_hyperv_platform(void)
 		!memcmp("Microsoft Hv", hyp_signature, 12);
 }
 
+static cycle_t read_hv_clock(struct clocksource *arg)
+{
+	cycle_t current_tick;
+	/*
+	 * Read the partition counter to get the current tick count. This count
+	 * is set to 0 when the partition is created and is incremented in
+	 * 100 nanosecond units.
+	 */
+	rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
+	return current_tick;
+}
+
+static struct clocksource hyperv_cs = {
+	.name           = "hyperv_clocksource",
+	.rating         = 400, /* use this when running on Hyperv*/
+	.read           = read_hv_clock,
+	.mask           = CLOCKSOURCE_MASK(64),
+};
+
 static void __init ms_hyperv_init_platform(void)
 {
 	/*

@@ -46,6 +67,9 @@ static void __init ms_hyperv_init_platform(void)
 
 	printk(KERN_INFO "HyperV: features 0x%x, hints 0x%x\n",
 	       ms_hyperv.features, ms_hyperv.hints);
+
+
+	clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
 }
 
 const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
drivers/staging/hv/Makefile +1 -1
index bd176b1..3e0d7e6 100644
@@ -1,4 +1,4 @@
-obj-$(CONFIG_HYPERV)		+= hv_vmbus.o hv_timesource.o
+obj-$(CONFIG_HYPERV)		+= hv_vmbus.o
 obj-$(CONFIG_HYPERV_STORAGE)	+= hv_storvsc.o
 obj-$(CONFIG_HYPERV_NET)	+= hv_netvsc.o
 obj-$(CONFIG_HYPERV_UTILS)	+= hv_utils.o
drivers/staging/hv/hv_timesource.c deleted +0 -101

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Signature · 1 line
1.7.4.1
Acked-by Greg Kroah-Hartman on v1 1/1
#1 lore raw
Quoted 7 lines · K. Y. Srinivasan

The Hyper-V timesource driver is best integrated with Hyper-V detection code
since: (a) Linux guests running on Hyper-V need this timesource and (b) by integrating with Hyper-V detection, we could significantly minimize the code in the timesource driver.

Signed-off-by K. Y. Srinivasan <[email protected]>
Signed-off-by Haiyang Zhang <[email protected]>
Acked-by Greg Kroah-Hartman <[email protected]>