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Message-ID: <20150116113913.13ece0f6@bbrezillon>
Date: Fri, 16 Jan 2015 11:39:13 +0100
From: Boris Brezillon <boris.brezillon@...e-electrons.com>
To: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Cc: Thomas Gleixner <tglx@...utronix.de>,
John Stultz <john.stultz@...aro.org>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Nicolas Ferre <nicolas.ferre@...el.com>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC 1/2] clocksource: track usage
Hi Alexandre,
On Fri, 16 Jan 2015 10:17:53 +0100
Alexandre Belloni <alexandre.belloni@...e-electrons.com> wrote:
> Track whether the clocksource is enabled or disabled.
>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
> ---
> include/linux/clocksource.h | 4 ++++
> kernel/time/clocksource.c | 26 ++++++++++++++++++++++++++
> kernel/time/timekeeping.c | 8 +++-----
> 3 files changed, 33 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
> index abcafaa20b86..7735902fc5f6 100644
> --- a/include/linux/clocksource.h
> +++ b/include/linux/clocksource.h
> @@ -210,6 +210,8 @@ struct clocksource {
> #define CLOCK_SOURCE_SUSPEND_NONSTOP 0x80
> #define CLOCK_SOURCE_RESELECT 0x100
>
> +#define CLOCK_SOURCE_USED 0x200
> +
> /* simplify initialization of mask field */
> #define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)
>
> @@ -282,6 +284,8 @@ static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift)
>
> extern int clocksource_register(struct clocksource*);
> extern int clocksource_unregister(struct clocksource*);
> +extern int clocksource_enable(struct clocksource *);
> +extern void clocksource_disable(struct clocksource *);
> extern void clocksource_touch_watchdog(void);
> extern struct clocksource* clocksource_get_next(void);
> extern void clocksource_change_rating(struct clocksource *cs, int rating);
> diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
> index b79f39bda7e1..920a4da58eb0 100644
> --- a/kernel/time/clocksource.c
> +++ b/kernel/time/clocksource.c
> @@ -889,6 +889,32 @@ int clocksource_unregister(struct clocksource *cs)
> }
> EXPORT_SYMBOL(clocksource_unregister);
>
> +/**
> + * clocksource_enable - enable a registered clocksource
> + * @cs: clocksource to enable
> + */
> +int clocksource_enable(struct clocksource *cs)
> +{
> + cs->flags |= CLOCK_SOURCE_USED;
> + if (cs->enable)
> + return cs->enable(cs);
I guess you should check cs->enable() return code before setting the
CLOCK_SOURCE_USED flag.
--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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