[PATCH] imx: distinguish POR from POR+WDOG reset cause for first wd

[Flavio Suligoi]

Hi Fabio,

> 
> Hi Flavio,
> 
> On Wed, Jan 22, 2020 at 11:18 AM Flavio Suligoi <f.suligoi at asem.it> wrote:
> >
> > In some application the possibility to check if the reset
> > is caused by a watchdog is essential, even if it occurs
> > simultaneously with POR.
> >
> > Signed-off-by: Flavio Suligoi <f.suligoi at asem.it>
> > ---
> >  arch/arm/mach-imx/cpu.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm/mach-imx/cpu.c b/arch/arm/mach-imx/cpu.c
> > index bfa85c6..ce0c663 100644
> > --- a/arch/arm/mach-imx/cpu.c
> > +++ b/arch/arm/mach-imx/cpu.c
> > @@ -47,7 +47,6 @@ static char *get_reset_cause(void)
> >  {
> >         switch (get_imx_reset_cause()) {
> >         case 0x00001:
> > -       case 0x00011:
> >                 return "POR";
> >         case 0x00004:
> >                 return "CSU";
> > @@ -59,6 +58,12 @@ static char *get_reset_cause(void)
> >  #else
> >                 return "WDOG";
> >  #endif
> > +       case 0x00011:
> > +#ifdef CONFIG_MX7
> > +               return "POR + WDOG1";
> > +#else
> > +               return "POR + WDOG";
> > +#endif
> >         case 0x00020:
> >                 return "JTAG HIGH-Z";
> >         case 0x00040:
> 
> If I understand this correctly your board has a WDOG_B pin connected
> to the PMIC and when WDOG_B is asserted the PMIC is power cycled and
> the system resets via POR.
> 
> Is this correct? If not, please describe exactly your setup and what
> you are trying to achieve.
> 
> It seems that the current behavior is correct for me.
> 
> Thanks

I'm currently use the imx8mm_evk board, with the PMIC
Rohom BD71847AMWV.
After a:

- power-on
- push-button reset
- a watchdog using the WDOG_B

the i.MX8MMini register SRC_SRSR (address 0x3039005C) is:
SRC_SRSR = 0x00000001 --> POR

but after a soft reset, from u-boot, using the WDOG1_WCR
(address 0x30280000):

mw.w 30280000 053C

we have:
SRC_SRSR = 0x00000011  --> POR + WDOG

and in this case is important for me to distinguish the two
different situation.

Thanks,

Flavio