Re: [PATCH v3 18/33] mips: inline serial_init

[Marc-André Lureau]

Hi

On Mon, Nov 18, 2019 at 7:25 PM Peter Maydell <address@hidden> wrote:
>
> On Wed, 23 Oct 2019 at 18:34, Marc-André Lureau
> <address@hidden> wrote:
> >
> > The function is specific to mipssim, let's inline it.
> >
> > Signed-off-by: Marc-André Lureau <address@hidden>
> > ---
> >  hw/char/serial.c         | 16 ----------------
> >  hw/mips/mips_mipssim.c   | 13 ++++++++++---
> >  include/hw/char/serial.h |  2 --
> >  3 files changed, 10 insertions(+), 21 deletions(-)
> >
> > diff --git a/hw/char/serial.c b/hw/char/serial.c
> > index 84de2740a7..ca95e09ec9 100644
> > --- a/hw/char/serial.c
> > +++ b/hw/char/serial.c
> > @@ -1023,22 +1023,6 @@ static const TypeInfo serial_io_info = {
> >      .class_init = serial_io_class_init,
> >  };
> >
> > -SerialIO *serial_init(int base, qemu_irq irq, int baudbase,
> > -                         Chardev *chr, MemoryRegion *system_io)
> > -{
> > -    SerialIO *self = SERIAL_IO(qdev_create(NULL, TYPE_SERIAL_IO));
> > -
> > -    qdev_prop_set_uint32(DEVICE(self), "baudbase", baudbase);
> > -    qdev_prop_set_chr(DEVICE(self), "chardev", chr);
> > -    qdev_prop_set_int32(DEVICE(self), "instance-id", base);
> > -    qdev_init_nofail(DEVICE(self));
> > -
> > -    sysbus_connect_irq(SYS_BUS_DEVICE(self), 0, irq);
> > -    memory_region_add_subregion(system_io, base, &self->serial.io);
> > -
> > -    return self;
> > -}
> > -
> >  static Property serial_properties[] = {
> >      DEFINE_PROP_CHR("chardev", SerialState, chr),
> >      DEFINE_PROP_UINT32("baudbase", SerialState, baudbase, 115200),
> > diff --git a/hw/mips/mips_mipssim.c b/hw/mips/mips_mipssim.c
> > index 282bbecb24..26fb8fa4de 100644
> > --- a/hw/mips/mips_mipssim.c
> > +++ b/hw/mips/mips_mipssim.c
> > @@ -40,6 +40,7 @@
> >  #include "hw/loader.h"
> >  #include "elf.h"
> >  #include "hw/sysbus.h"
> > +#include "hw/qdev-properties.h"
> >  #include "exec/address-spaces.h"
> >  #include "qemu/error-report.h"
> >  #include "sysemu/qtest.h"
> > @@ -219,9 +220,15 @@ mips_mipssim_init(MachineState *machine)
> >       * A single 16450 sits at offset 0x3f8. It is attached to
> >       * MIPS CPU INT2, which is interrupt 4.
> >       */
> > -    if (serial_hd(0))
> > -        serial_init(0x3f8, env->irq[4], 115200, serial_hd(0),
> > -                    get_system_io());
> > +    if (serial_hd(0)) {
> > +        DeviceState *dev = qdev_create(NULL, TYPE_SERIAL_IO);
> > +
> > +        qdev_prop_set_chr(dev, "chardev", serial_hd(0));
> > +        qdev_prop_set_int32(dev, "instance-id", 0x3f8);
> > +        qdev_init_nofail(dev);
> > +        sysbus_connect_irq(SYS_BUS_DEVICE(dev), 0, env->irq[4]);
> > +        sysbus_add_io(SYS_BUS_DEVICE(dev), 0x3f8, 
> > &SERIAL_IO(dev)->serial.io);
> > +    }
>
> The code being inlined here doesn't seem to be identical to the
> code in the function above (it uses sysbus_add_io() rather than
> memory_region_add_subregion()).

sysbus_add_io() is memory_region_add_subregion(get_system_io(), ...).

I went a step too fast, let's make it a seperate patch to clarify it then.

>
> It's also a bit ugly that the code has to reach into the
> internals of the device to get the MemoryRegion pointer.
> Would it work to have the device use sysbus_init_mmio()
> in its init or realize method to register the IO port MemoryRegion,
> and then we could use sysbus_mmio_get_region() to get the
> MemoryRegion pointer ?

Sure, seems fine to me. The caller must have extra knowledge of the
memory region number though. This seems a bit fragile to me, compared
to static compilation checking.

>
> (If that does work, we should someday refactor
> sysbus_add_io() so that all the devices it's used with
> register the MemoryRegions that way, and then sysbus_add_io()
> can just take an 'int n' the way sysbus_mmio_map() does.
> But not today.)

I see, left for another day