[PATCH v3 22/30] board: emulation: Add QEMU sbsa support

[Patrick Rudolph]

On Mon, Sep 16, 2024 at 5:41 PM Simon Glass <sjg at chromium.org> wrote:
>
> Hi Patrick,
>
> On Thu, 12 Sept 2024 at 00:23, Patrick Rudolph
> <patrick.rudolph at 9elements.com> wrote:
> >
> > On Thu, Sep 12, 2024 at 2:58 AM Simon Glass <sjg at chromium.org> wrote:
> > >
> > > Hi Patrick,
> > >
> > > On Wed, 11 Sept 2024 at 00:26, Patrick Rudolph
> > > <patrick.rudolph at 9elements.com> wrote:
> > > >
> > > > Add support for Arm sbsa [1] v0.3+ that is supported by QEMU [2].
> > > >
> > > > Unlike other Arm based platforms the machine only provides a minimal
> > > > FDT that contains number of CPUs, ammount of memory and machine-version.
> > > > The boot firmware has to provide ACPI tables to the OS.
> > > >
> > > > Add a minimal amount of devicetree nodes to make the board useable within
> > > > U-Boot, provide documentation how to use, enable binman to fabricate both
> > > > ROMs that are required to boot and add ACPI tables to make it full compatible
> > > > to the EDK2 reference implementation.
> > > >
> > > > The board was tested using Fedora 40 Aarch64 Workstation. It's able
> > > > to boot from USB and AHCI or network.
> > > >
> > > > Tested and found working:
> > > > - serial
> > > > - PCI
> > > > - xHCI
> > > > - Bochs display
> > > > - AHCI
> > > > - network using e1000e
> > > > - CPU init
> > > > - Booting Fedora 40
> > > >
> > > > 1: Server Base System Architecture (SBSA)
> > > > 2: https://www.qemu.org/docs/master/system/arm/sbsa.html
> > > >
> > > > Signed-off-by: Patrick Rudolph <patrick.rudolph at 9elements.com>
> > > > Cc: Peter Robinson <pbrobinson at gmail.com>
> > > > Cc: Simon Glass <sjg at chromium.org>
> > > > Cc: Tom Rini <trini at konsulko.com>
> > > > ---
> > > > Changelog v3:
> > > > - Add GIC and GIC-ITS to devicetree
> > > > - Select GICv3 driver
> > > > - Drop acpi_fill_madt and use driver model instead
> > > >
> > > > ---
> > > >  arch/arm/Kconfig                            |   1 +
> > > >  arch/arm/dts/qemu-sbsa.dts                  |  49 ++
> > > >  arch/arm/include/asm/arch-qemu-sbsa/boot0.h |  33 ++
> > > >  arch/arm/mach-qemu/Kconfig                  |  36 +-
> > > >  board/emulation/qemu-arm/MAINTAINERS        |   2 +
> > > >  board/emulation/qemu-sbsa/Kconfig           |  58 +++
> > > >  board/emulation/qemu-sbsa/Makefile          |   8 +
> > > >  board/emulation/qemu-sbsa/acpi.c            | 235 ++++++++++
> > > >  board/emulation/qemu-sbsa/dsdt.asl          | 483 ++++++++++++++++++++
> > > >  board/emulation/qemu-sbsa/lowlevel_init.S   |  22 +
> > > >  board/emulation/qemu-sbsa/qemu-sbsa.c       | 481 +++++++++++++++++++
> > > >  board/emulation/qemu-sbsa/qemu-sbsa.env     |  14 +
> > > >  board/emulation/qemu-sbsa/qemu-sbsa.h       |  38 ++
> > > >  board/emulation/qemu-sbsa/smc.c             |  72 +++
> > > >  configs/qemu-arm-sbsa_defconfig             |  10 +
> > > >  doc/board/emulation/index.rst               |   1 +
> > > >  doc/board/emulation/qemu-sbsa.rst           |  98 ++++
> > > >  doc/develop/driver-model/virtio.rst         |   1 +
> > > >  include/configs/qemu-sbsa.h                 |  98 ++++
> > > >  19 files changed, 1734 insertions(+), 6 deletions(-)
> > > >  create mode 100644 arch/arm/dts/qemu-sbsa.dts
> > > >  create mode 100644 arch/arm/include/asm/arch-qemu-sbsa/boot0.h
> > > >  create mode 100644 board/emulation/qemu-sbsa/Kconfig
> > > >  create mode 100644 board/emulation/qemu-sbsa/Makefile
> > > >  create mode 100644 board/emulation/qemu-sbsa/acpi.c
> > > >  create mode 100644 board/emulation/qemu-sbsa/dsdt.asl
> > > >  create mode 100644 board/emulation/qemu-sbsa/lowlevel_init.S
> > > >  create mode 100644 board/emulation/qemu-sbsa/qemu-sbsa.c
> > > >  create mode 100644 board/emulation/qemu-sbsa/qemu-sbsa.env
> > > >  create mode 100644 board/emulation/qemu-sbsa/qemu-sbsa.h
> > > >  create mode 100644 board/emulation/qemu-sbsa/smc.c
> > > >  create mode 100644 configs/qemu-arm-sbsa_defconfig
> > > >  create mode 100644 doc/board/emulation/qemu-sbsa.rst
> > > >  create mode 100644 include/configs/qemu-sbsa.h
> > >
> > > Wow there is a lot in this patch!
> > >
> > > I don't think this should be in a separate subdir, just using
> > > board/emulation/qemu-arm should be OK?
> > Why would it share the code base with qemu-arm, as it's a completely
> > different board?
>
> Perhaps I misunderstand this...what kind of board is it? How do you
> run qemu for this board?
>
For QEMU SBSA you use -machine sbsa-ref, but for qemu-arm you use -machine virt.

Both can use a cortex-a57 as CPU, but that's all those boards share. They have a
different memory layout, virt provides a complete FDT, while sbsa-ref doesn't.
sbsa-ref needs an Arm-TF and nonsecure boot firmware, while virt works
without a firmware.

> >
> > >
> > > I see you are setting plat data in the board file...is there not a CPU
> > > driver which can read it from the devicetree or set it based on the
> > > compatible string?
> > The CPU driver could read the data from devicetree, but that would require a new
> > DT binding. Is that the preferred method over using plat data?
>
> It is fine to use plat data...but it should be set up in the driver
> where possible. In this case if you don't have a binding you can check
> the compatible string of the device (or even the root
> compatible-string) and add your plat data if it matches.

I was able to parse everything from the DT, except for PMU IRQs. Those
aren't needed to
boot the platform and can be added later on.
Will send out a new revision soon.

>
>
> >
> > >
> > > For FDT fixup, can you please use the event and the ofnode interface?
> > > See EVT_FT_FIXUP and bootmeth_vbe_ft_fixup() as an example.

It looks like EVT_FT_FIXUP is run rather late in the bootflow, used to
updated the FDT for OS usage,
but it must be run early to update the minimal FDT passed by QEMU and
add the missing nodes
for U-Boot drivers.

> Regards,
> Simon