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Date:	Fri, 28 Mar 2008 18:14:36 +0300
From:	Sergei Shtylyov <sshtylyov@ru.mvista.com>
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To:	Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc:	ralf@linux-mips.org, linux-mips@linux-mips.org, ncoesel@DEALogic.nl
Subject: Re: Alchemy power managment code.
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Hello.

Atsushi Nemoto wrote:

>>>Correct - and cevt-r4k won't be usable either.  I guess that means you
>>>leave the user the choice between either these two or using wait.  Not
>>>nice but ...

>>    The Alchemy code doesn't even try to use CP0 counter when CONFIG_PM=y if 
>>you look into arch/mips/au1000/common/time.c... or at least it didn't before 
>>Atsushi removed do_fast_pm_gettimeoffset().

> Oh, yes. At that time I tried to implement clocksource drivers for
> non-standard timers, but it seems I had missied Alchemy PM=y case.

> The driver would be something like this?  Completely untested ;-)

> static cycle_t au1000_hpt_read(void)
> {
> 	return au_readl(SYS_TOYREAD);
> }

> struct clocksource au1000_clocksource = {
> 	.name	= "au1000-counter",
> 	.rating	= 200,

    Rating should be greater than that of CP0 counter...

> 	.read	= au1000_hpt_read,
> 	.mask	= CLOCKSOURCE_MASK(32),
> 	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
> };

> void __init au1000_clocksource_init(unsinged long cpu_speed)
> {
> 	struct clocksource *cs = &au1000_clocksource;
> 
> 	clocksource_set_clock(cs, cpu_speed);

    Not really, it's clocked by 32768 Hz input, so probably not very good as a 
clocksource.

> 	clocksource_register(cs);
> }

WBR, Sergei