Re: [Qemu-devel] [PATCH v2 1/3] lsi53c895a: hide 53c895a registers in 53c810

[Artyom Tarasenko]

On Sun, May 5, 2019 at 12:43 PM Mark Cave-Ayland
<address@hidden> wrote:
>
> On 04/05/2019 22:02, Artyom Tarasenko wrote:
>
> > AIX/PReP does access to the aliased IO registers of 53810.
> > Implement aliasing to make the AIX driver work.
> >
> > Signed-off-by: Artyom Tarasenko <address@hidden>
> > ---
> >  hw/scsi/lsi53c895a.c | 17 ++++++++++++++---
> >  1 file changed, 14 insertions(+), 3 deletions(-)
> >
> > diff --git a/hw/scsi/lsi53c895a.c b/hw/scsi/lsi53c895a.c
> > index da7239d..6b95699 100644
> > --- a/hw/scsi/lsi53c895a.c
> > +++ b/hw/scsi/lsi53c895a.c
> > @@ -2271,6 +2271,9 @@ static void lsi_scsi_realize(PCIDevice *dev, Error 
> > **errp)
> >      LSIState *s = LSI53C895A(dev);
> >      DeviceState *d = DEVICE(dev);
> >      uint8_t *pci_conf;
> > +    uint64_t mmio_size;
> > +    MemoryRegion *mr;
> > +    uint16_t type = PCI_DEVICE_GET_CLASS(dev)->device_id;
> >
> >      pci_conf = dev->config;
> >
> > @@ -2279,13 +2282,21 @@ static void lsi_scsi_realize(PCIDevice *dev, Error 
> > **errp)
> >      /* Interrupt pin A */
> >      pci_conf[PCI_INTERRUPT_PIN] = 0x01;
> >
> > -    memory_region_init_io(&s->mmio_io, OBJECT(s), &lsi_mmio_ops, s,
> > -                          "lsi-mmio", 0x400);
> >      memory_region_init_io(&s->ram_io, OBJECT(s), &lsi_ram_ops, s,
> >                            "lsi-ram", 0x2000);
> >      memory_region_init_io(&s->io_io, OBJECT(s), &lsi_io_ops, s,
> >                            "lsi-io", 256);
> > -
> > +    if (type == PCI_DEVICE_ID_LSI_53C895A) {
> > +        mmio_size = 0x400;
> > +    } else {
> > +        mr = g_new(MemoryRegion, 1);
>
> In general these days it's worth keeping the reference to the MemoryRegion 
> within
> LSIState since then its lifecycle is more clearly defined.

On the other hand, it's a PCI card, and can not be
hot-plugged/removed, so the lifecycle is pretty simple here.
Or am I missing something?

> > +        memory_region_init_alias(mr, OBJECT(d), "lsi-io-alias", &s->io_io,
> > +                                 0, 0x80);
> > +        memory_region_add_subregion_overlap(&s->io_io, 0x80, mr, -1);
> > +        mmio_size = 0x80;
>
> This feels a little strange - is it possible to see from the datasheets that 
> the
> 53C895A has 0x400 bytes MMIO whilst the 53C810 has 0x80 bytes MMIO? It's not 
> clear to
> me where the aliasing is happening.

These values are empiric. For 810 it can not be more than 0x80,
because the AIX does access the registers with the shift of 0x80.
For  895A we did already have 0x400.

> > +    }
> > +    memory_region_init_io(&s->mmio_io, OBJECT(s), &lsi_mmio_ops, s,
> > +                          "lsi-mmio", mmio_size);
> >      address_space_init(&s->pci_io_as, pci_address_space_io(dev), 
> > "lsi-pci-io");
> >      qdev_init_gpio_out(d, &s->ext_irq, 1);
> >
> >
>
>
> ATB,
>
> Mark.
>


-- 
Regards,
Artyom Tarasenko

SPARC and PPC PReP under qemu blog: http://tyom.blogspot.com/search/label/qemu