[U-Boot] [PATCH 1/3] crypto/fsl - disable RNG oscillator maximum frequency check

[Ruchika Gupta]

Acked-by: Ruchika Gupta<ruchika.gupta at freescale.com>

> -----Original Message-----
> From: Sun York-R58495
> Sent: Sunday, July 19, 2015 3:43 AM
> To: Gupta Ruchika-R66431
> Subject: Re: [PATCH 1/3] crypto/fsl - disable RNG oscillator maximum
> frequency check
> 
> Ruchika,
> 
> Please comment/ack this patch and others in this set.
> 
> York
> 
> 
> On 05/05/2015 06:48 AM, Alex Porosanu wrote:
> > The rtfrqmax & rtfrqmin set the bounds of the expected frequency of
> > the oscillator, when SEC runs at its maximum frequency. For certain
> > platforms (f.i. T2080), the oscillator is very fast and thus if the
> > SEC runs at a lower than normal frequency, the ring oscillator is
> > incorrectly detected as being out of bounds.
> >
> > This patch effectively disables the maximum frequency check, by
> > setting a high enough maximum allowable frequency for the oscillator.
> > The reasoning behind this is that usually a broken oscillator will run
> > too slow (i.e. not run at all) rather than run too fast.
> >
> > Signed-off-by: Alex Porosanu <alexandru.porosanu at freescale.com>
> > ---
> >  drivers/crypto/fsl/jr.c | 4 ++--
> >  include/fsl_sec.h       | 1 +
> >  2 files changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/crypto/fsl/jr.c b/drivers/crypto/fsl/jr.c index
> > f99d594..aa527ec 100644
> > --- a/drivers/crypto/fsl/jr.c
> > +++ b/drivers/crypto/fsl/jr.c
> > @@ -406,8 +406,8 @@ static void kick_trng(int ent_delay)
> >  	sec_out32(&rng->rtsdctl, val);
> >  	/* min. freq. count, equal to 1/4 of the entropy sample length */
> >  	sec_out32(&rng->rtfreqmin, ent_delay >> 2);
> > -	/* max. freq. count, equal to 8 times the entropy sample length */
> > -	sec_out32(&rng->rtfreqmax, ent_delay << 3);
> > +	/* disable maximum frequency count */
> > +	sec_out32(&rng->rtfreqmax, RTFRQMAX_DISABLE);
> >  	/* put RNG4 into run mode */
> >  	sec_clrbits32(&rng->rtmctl, RTMCTL_PRGM);  } diff --git
> > a/include/fsl_sec.h b/include/fsl_sec.h index ebb1ac6..14f6633 100644
> > --- a/include/fsl_sec.h
> > +++ b/include/fsl_sec.h
> > @@ -49,6 +49,7 @@ struct rng4tst {
> >  		u32 rttotsam;	/* PRGM=0: total samples register */
> >  	};
> >  	u32 rtfreqmin;		/* frequency count min. limit register */
> > +#define RTFRQMAX_DISABLE       (1 << 20)
> >  	union {
> >  		u32 rtfreqmax;	/* PRGM=1: freq. count max. limit register */
> >  		u32 rtfreqcnt;	/* PRGM=0: freq. count register */
> >