[PATCH v4 4/4] powerpc/85xx: add sysfs for pw20 state and altivec idle

[Wang Dongsheng-B40534]

> -----Original Message-----
> From: Bhushan Bharat-R65777
> Sent: Wednesday, September 25, 2013 2:23 PM
> To: Wang Dongsheng-B40534; Wood Scott-B07421
> Cc: linuxppc-dev at lists.ozlabs.org; Wang Dongsheng-B40534
> Subject: RE: [PATCH v4 4/4] powerpc/85xx: add sysfs for pw20 state and
> altivec idle
> 
> 
> 
> > -----Original Message-----
> > From: Linuxppc-dev [mailto:linuxppc-dev-
> > bounces+bharat.bhushan=freescale.com at lists.ozlabs.org] On Behalf Of
> > bounces+Dongsheng
> > Wang
> > Sent: Tuesday, September 24, 2013 2:59 PM
> > To: Wood Scott-B07421
> > Cc: linuxppc-dev at lists.ozlabs.org; Wang Dongsheng-B40534
> > Subject: [PATCH v4 4/4] powerpc/85xx: add sysfs for pw20 state and
> > altivec idle
> >
> > From: Wang Dongsheng <dongsheng.wang at freescale.com>
> >
> > Add a sys interface to enable/diable pw20 state or altivec idle, and
> > control the wait entry time.
> >
> > Enable/Disable interface:
> > 0, disable. 1, enable.
> > /sys/devices/system/cpu/cpuX/pw20_state
> > /sys/devices/system/cpu/cpuX/altivec_idle
> >
> > Set wait time interface:(Nanosecond)
> > /sys/devices/system/cpu/cpuX/pw20_wait_time
> > /sys/devices/system/cpu/cpuX/altivec_idle_wait_time
> > Example: Base on TBfreq is 41MHZ.
> > 1~47(ns): TB[63]
> > 48~95(ns): TB[62]
> > 96~191(ns): TB[61]
> > 192~383(ns): TB[62]
> > 384~767(ns): TB[60]
> > ...
> >
> > Signed-off-by: Wang Dongsheng <dongsheng.wang at freescale.com>
> > ---
> > *v4:
> > Move code from 85xx/common.c to kernel/sysfs.c.
> >
> > Remove has_pw20_altivec_idle function.
> >
> > Change wait "entry_bit" to wait time.
> >
> >  arch/powerpc/kernel/sysfs.c | 291
> > ++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 291 insertions(+)
> >
> > diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
> > index 27a90b9..23fece6 100644
> > --- a/arch/powerpc/kernel/sysfs.c
> > +++ b/arch/powerpc/kernel/sysfs.c
> > @@ -85,6 +85,279 @@ __setup("smt-snooze-delay=",
> > setup_smt_snooze_delay);
> >
> >  #endif /* CONFIG_PPC64 */
> >
> > +#ifdef CONFIG_FSL_SOC
> > +#define MAX_BIT		63
> > +
> > +static u64 pw20_wt;
> > +static u64 altivec_idle_wt;
> > +
> > +static unsigned int get_idle_ticks_bit(u64 ns) {
> > +	u64 cycle;
> > +
> > +	cycle = div_u64(ns, 1000 / tb_ticks_per_usec);
> 
> When tb_ticks_per_usec  > 1000 (timebase frequency > 1GHz) then this will
> always be ns, which is not correct, no?
> 
"1000 / tb_ticks_per_usec" means nsec_ticks_per_tb

If timebase frequency > 1GHz, this should be "tb_ticks_per_usec / 1000" and to get tb_ticks_per_nsec.
This should be changed to "cycle = ns * tb_ticks_per_nsec;"

But at present we do not have such a platform that timebase frequency more than 1GHz. And I think it is not need to support such a situation. Because we have no environment to test it.

If later there will be more than 1GHZ platform at that time to add this support.

Thanks.

-dongsheng