On 17/01/2017 at 09:24:17 +0100, Fabien Lahoudere wrote :
> On Mon, 2017-01-16 at 18:50 +0100, Alexandre Belloni wrote:
> > Hi,
> >
> > On 12/01/2017 at 11:43:37 +0100, Fabien Lahoudere wrote :
> > > If RTC time have been altered by low voltage, we notify users
> > > that RTC time is invalid by returning -EINVAL.
> > > The RTC time needs to be set correctly to clear the invalid flag.
> > > If the RTC is not set before restarting, the information will be lost.
> > >
> > > Signed-off-by: Fabien Lahoudere <fabien.lahoud...@collabora.co.uk>
> > > ---
> > > drivers/rtc/rtc-s35390a.c | 9 +++++++++
> > > 1 file changed, 9 insertions(+)
> > >
> > > diff --git a/drivers/rtc/rtc-s35390a.c b/drivers/rtc/rtc-s35390a.c
> > > index 5dab466..ef4ada9 100644
> > > --- a/drivers/rtc/rtc-s35390a.c
> > > +++ b/drivers/rtc/rtc-s35390a.c
> > > @@ -62,6 +62,7 @@ struct s35390a {
> > > struct i2c_client *client[8];
> > > struct rtc_device *rtc;
> > > int twentyfourhour;
> > > + int isinvalid;
> > > };
> > >
> > > static int s35390a_set_reg(struct s35390a *s35390a, int reg, char *buf,
> > > int len)
> > > @@ -135,6 +136,8 @@ static int s35390a_reset(struct s35390a *s35390a,
> > > char *status1)
> > > * The 24H bit is kept over reset, so set it already here.
> > > */
> > > initialize:
> > > + /* set the RTC time as invalid */
> > > + s35390a->isinvalid = 1;
> > > *status1 = S35390A_FLAG_24H;
> > > buf = S35390A_FLAG_RESET | S35390A_FLAG_24H;
> > > ret = s35390a_set_reg(s35390a, S35390A_CMD_STATUS1, &buf, 1);
> > > @@ -221,6 +224,8 @@ static int s35390a_set_datetime(struct i2c_client
> > > *client, struct rtc_time *tm)
> > > buf[i] = bitrev8(buf[i]);
> > >
> > > err = s35390a_set_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
> > > + if (err >= 0)
> > > + s35390a->isinvalid = 0;
> > >
> > > return err;
> > > }
> > > @@ -231,6 +236,9 @@ static int s35390a_get_datetime(struct i2c_client
> > > *client, struct rtc_time *tm)
> > > char buf[7];
> > > int i, err;
> > >
> > > + if (s35390a->isinvalid)
> > > + return -EINVAL;
> > > +
> >
> > That's fine but what happens if it became invalid between probe and
> > s35390a_get_datetime()? (This is particularly relevant after patch 2/2.
>
> This is not possible with our design. When the system is on, its power
> supply replace the backup battery. (See p38 Figure 49).
>
Well, it depends on the tolerances of each components (but yeah, I doubt
your SoC is more tolerant than the RTC).
> If you prefer I can call s35390a_reset if s35390a->isinvalid is set to
> 0?
>
Actually, after reading the datasheet, I realize it is only POC that is
reset to 0 after reading so isinvalid is not needed. Just read status1
and look for BLD instead of caching it.
I think it is probably worth separating s35390a_reset() into two
functions. One that does the initialization and another one that reads
status1 and immediately doest the initialization when POC is set. If BLD
is set, then we can wait for set_time to happen before initializing.
--
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
--
You received this message because you are subscribed to "rtc-linux".
Membership options at http://groups.google.com/group/rtc-linux .
Please read http://groups.google.com/group/rtc-linux/web/checklist
before submitting a driver.
---
You received this message because you are subscribed to the Google Groups
"rtc-linux" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to rtc-linux+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
