[PATCH] bsps/raspberrypi: Add SEV instruction to Pi SMP

[Pranav Dangi]

The Pi firmware added a wfe(wait for event) so now, the cores 1-3 wait
for the start address being written to the mailbox register, followed
by a SEV that acts as a poke to the mailbox, or in other words, a wfe
wake-up event. I've added the SEV correspondingly here. So, would 'Add
SEV instruction' be the right way to say it? Or should I change the
subject.

Thanks,
pranav


On Fri, Aug 6, 2021 at 7:24 PM Joel Sherrill <joel at rtems.org> wrote:
>
> On Fri, Aug 6, 2021 at 5:11 AM pranav <dangipranav at gmail.com> wrote:
> >
> > Add Send Event instruction to get the SMP working on the Pi. Patch
> > doesn't work for SMP on Pi 2 v1.1
> > ---
> >  bsps/arm/raspberrypi/include/bsp/irq.h | 1 +
> >  bsps/arm/raspberrypi/start/bspsmp.c    | 1 +
> >  2 files changed, 2 insertions(+)
> >
> > diff --git a/bsps/arm/raspberrypi/include/bsp/irq.h b/bsps/arm/raspberrypi/include/bsp/irq.h
> > index a363e7ce90..2c0d0d82b2 100644
> > --- a/bsps/arm/raspberrypi/include/bsp/irq.h
> > +++ b/bsps/arm/raspberrypi/include/bsp/irq.h
> > @@ -24,6 +24,7 @@
> >  #include <rtems.h>
> >  #include <rtems/irq.h>
> >  #include <rtems/irq-extension.h>
> > +#include <dev/irq/arm-gic-irq.h>
> >
> >  /**
> >   * @defgroup raspberrypi_interrupt Interrrupt Support
> > diff --git a/bsps/arm/raspberrypi/start/bspsmp.c b/bsps/arm/raspberrypi/start/bspsmp.c
> > index 44f7a1d376..9dcfb0fb03 100644
> > --- a/bsps/arm/raspberrypi/start/bspsmp.c
> > +++ b/bsps/arm/raspberrypi/start/bspsmp.c
> > @@ -42,6 +42,7 @@ bool _CPU_SMP_Start_processor( uint32_t cpu_index )
> >    if (cpu_index != cpu_index_self) {
> >
> >      BCM2835_REG(BCM2836_MAILBOX_3_WRITE_SET_BASE + 0x10 * cpu_index) = (uint32_t)_start;
> > +    _ARM_Send_event();
>
> Perhaps a bit pedantic but you didn't add an SEV instruction directly.
> You added a call to send an event which is implemented (I guess) as an
> SEV instruction.
>
> Subject of patch might be better as something like "add sending event to ..."
> and maybe add a comment as to what the send event is intended to convey.
> >
> >      /*
> >       * Wait for secondary processor to complete its basic initialization so
> > --
> > 2.30.2
> >
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