linux-kernel - RE: [PATCH 1/1] Clocksource: Move the Hyper-V clocksource driver out of staging

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Message-ID: <6E21E5352C11B742B20C142EB499E0481FC8C6@TK5EX14MBXC122.redmond.corp.microsoft.com>
Date:	Mon, 23 May 2011 18:43:02 +0000
From:	KY Srinivasan <kys@...rosoft.com>
To:	john stultz <johnstul@...ibm.com>
CC:	"gregkh@...e.de" <gregkh@...e.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"hch@...radead.org" <hch@...radead.org>,
	Hank Janssen <hjanssen@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>
Subject: RE: [PATCH 1/1] Clocksource: Move the Hyper-V clocksource driver
 out of staging



> -----Original Message-----
> From: john stultz [mailto:johnstul@...ibm.com]
> Sent: Monday, May 23, 2011 2:40 PM
> To: KY Srinivasan
> Cc: gregkh@...e.de; linux-kernel@...r.kernel.org;
> devel@...uxdriverproject.org; tglx@...utronix.de; hch@...radead.org; Hank
> Janssen; Haiyang Zhang
> Subject: Re: [PATCH 1/1] Clocksource: Move the Hyper-V clocksource driver out
> of staging
> 
> On Mon, 2011-05-23 at 10:12 -0700, K. Y. Srinivasan wrote:
> > Move the Hyper-V clocksource driver out of staging.
> >
> > Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
> > Signed-off-by: Hank Janssen <hjanssen@...rosoft.com>
> > Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.com>
> > ---
> >  drivers/clocksource/Makefile        |    1 +
> >  drivers/clocksource/hv_timesource.c |  102
> +++++++++++++++++++++++++++++++++++
> >  drivers/staging/hv/Makefile         |    2 +-
> >  drivers/staging/hv/hv_timesource.c  |  102 -----------------------------------
> >  4 files changed, 104 insertions(+), 103 deletions(-)
> >  create mode 100644 drivers/clocksource/hv_timesource.c
> >  delete mode 100644 drivers/staging/hv/hv_timesource.c
> >
> > diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> > index be61ece..ea44327 100644
> > --- a/drivers/clocksource/Makefile
> > +++ b/drivers/clocksource/Makefile
> > @@ -6,3 +6,4 @@ obj-$(CONFIG_CS5535_CLOCK_EVENT_SRC)	+= cs5535-
> clockevt.o
> >  obj-$(CONFIG_SH_TIMER_CMT)	+= sh_cmt.o
> >  obj-$(CONFIG_SH_TIMER_MTU2)	+= sh_mtu2.o
> >  obj-$(CONFIG_SH_TIMER_TMU)	+= sh_tmu.o
> > +obj-$(CONFIG_HYPERV)		+= hv_timesource.o
> > diff --git a/drivers/clocksource/hv_timesource.c
> b/drivers/clocksource/hv_timesource.c
> > new file mode 100644
> > index 0000000..0efb049
> > --- /dev/null
> > +++ b/drivers/clocksource/hv_timesource.c
> > @@ -0,0 +1,102 @@
> > +/*
> > + * A clocksource for Linux running on HyperV.
> > + *
> > + *
> > + * Copyright (C) 2010, Novell, Inc.
> > + * Author : K. Y. Srinivasan <ksrinivasan@...ell.com>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope that it will be useful, but
> > + * WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE
> or
> > + * NON INFRINGEMENT.  See the GNU General Public License for more
> > + * details.
> > + *
> > + * You should have received a copy of the GNU General Public License
> > + * along with this program; if not, write to the Free Software
> > + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
> > + *
> > + */
> > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> > +
> > +#include <linux/version.h>
> > +#include <linux/clocksource.h>
> > +#include <linux/init.h>
> > +#include <linux/module.h>
> > +#include <linux/pci.h>
> > +#include <linux/dmi.h>
> > +#include <asm/hyperv.h>
> > +#include <asm/mshyperv.h>
> > +#include <asm/hypervisor.h>
> > +
> > +#define HV_CLOCK_SHIFT	22
> > +
> > +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),
> > +	/*
> > +	 * The time ref counter in HyperV is in 100ns units.
> > +	 * The definition of mult is:
> > +	 * mult/2^shift = ns/cyc = 100
> > +	 * mult = (100 << shift)
> > +	 */
> > +	.mult           = (100 << HV_CLOCK_SHIFT),
> > +	.shift          = HV_CLOCK_SHIFT,
> 
> The mult/shift assignments can be dropped. Please use
> clocksource_register_hz/khz() which will assign mult/shift for you.
> 
> Otherwise it looks pretty straightforward.

Will do; thanks.
> 
> 
> > +module_init(init_hv_clocksource);
> > +MODULE_DESCRIPTION("HyperV based clocksource");
> > +MODULE_AUTHOR("K. Y. Srinivasan <ksrinivasan@...ell.com>");
> > +MODULE_LICENSE("GPL");
> 
> One other nit: Should this email address be updated to your current one?

I will update it.

Regards,

K. Y