The correct spelling is R-Car, including the dash, update the usage.
Kconfig strings and comment changes only, no functional change.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>

Patrick Rudolph <patrick.rudolph@9elements.com> says:

Based on the existing work done by Simon Glass this series adds
support for booting aarch64 devices using ACPI only.
As first target QEMU SBSA support is added, which relies on ACPI
only to boot an OS. As secondary target the Raspberry Pi4 was used,
which is broadly available and allows easy testing of the proposed
solution.

The series is split into ACPI cleanups and code movements, adding
Arm specific ACPI tables and finally SoC and mainboard related
changes to boot a Linux on the QEMU SBSA and RPi4. Currently only the
mandatory ACPI tables are supported, allowing to boot into Linux
without errors.

The QEMU SBSA support is feature complete and provides the same
functionality as the EDK2 implementation.

The changes were tested on real hardware as well on QEMU v9.0:

qemu-system-aarch64 -machine sbsa-ref -nographic -cpu cortex-a57 \
                    -pflash secure-world.rom \
                    -pflash unsecure-world.rom

qemu-system-aarch64 -machine raspi4b -kernel u-boot.bin -cpu cortex-a72 \
-smp 4 -m 2G -drive file=raspbian.img,format=raw,index=0 \
-dtb bcm2711-rpi-4-b.dtb -nographic

Tested against FWTS V24.03.00.

Known issues:
- The QEMU rpi4 support is currently limited as it doesn't emulate PCI,
  USB or ethernet devices!
- The SMP bringup doesn't work on RPi4, but works in QEMU (Possibly
  cache related).
- PCI on RPI4 isn't working on real hardware since the pcie_brcmstb
  Linux kernel module doesn't support ACPI yet.

Link: https://lore.kernel.org/r/20241023132116.970117-1-patrick.rudolph@9elements.com

When ACPI is enabled on arm it will use the getinfo function to fill
the SPCR ACPI table.

Signed-off-by: Maximilian Brune <maximilian.brune@9elements.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>
Reviewed-by: Moritz Fischer <moritzf@google.com>

Rasmus Villemoes <ravi@prevas.dk> says:

Some small improvements to the serial rx buffer feature.

CI seems happy: https://github.com/u-boot/u-boot/pull/674

Link: https://lore.kernel.org/r/20241003141029.920035-1-ravi@prevas.dk

The initialization of upriv->buf doesn't check for a NULL return. But
there's actually no point in doing a separate, unconditional malloc()
in post_probe; we can just make serial_dev_priv contain the rx buffer
itself, and let the (larger) allocation be handled by the driver core
when it allocates the ->per_device_auto. The total run-time memory
used is mostly the same, we reduce the code size a little, and as a
bonus, struct serial_dev_priv does not contain the unused members when
!SERIAL_RX_BUFFER.

Signed-off-by: Rasmus Villemoes <ravi@prevas.dk>
Reviewed-by: Simon Glass <sjg@chromium.org>

The help text says it must be a power of 2, and the implementation
does rely on that. Enforce it.

A violation gives a wall of text, but the last few lines should be
reasonably obvious:

drivers/serial/serial-uclass.c:334:9: note: in expansion of macro ‘BUILD_BUG_ON_NOT_POWER_OF_2’
  334 |         BUILD_BUG_ON_NOT_POWER_OF_2(CONFIG_SERIAL_RX_BUFFER_SIZE);

Signed-off-by: Rasmus Villemoes <ravi@prevas.dk>
Reviewed-by: Simon Glass <sjg@chromium.org>

Before the previous patch, pasting a string of length x >
CONFIG_SERIAL_RX_BUFFER_SIZE results in getting the
last (x%CONFIG_SERIAL_RX_BUFFER_SIZE) characters from that string.

With the previous patch, one instead gets the last
CONFIG_SERIAL_RX_BUFFER_SIZE characters repeatedly until the ->rd_ptr
catches up.

Both behaviours are counter-intuitive, and happen because the code
that checks for a character available from the hardware does not
account for whether there is actually room in the software buffer to
receive it. Fix that by adding such accounting. This also brings the
software buffering more in line with how most hardware FIFOs
behave (first received characters are kept, overflowing characters are
dropped).

Signed-off-by: Rasmus Villemoes <ravi@prevas.dk>
Reviewed-by: Simon Glass <sjg@chromium.org>

The current implementation of the circular rx buffer falls into a
common trap with circular buffers: It keeps the head/tail indices
reduced modulo the buffer size. The problem with that is that it makes
it impossible to distinguish "buffer full" from "buffer empty",
because in both situations one has head==tail.

This can easily be demonstrated: Build sandbox with RX_BUFFER enabled,
set the RX_BUFFER_SIZE to 32, and try pasting the string

  01234567890123456789012345678901

Nothing seems to happen, but in reality, all characters have been read
and put into the buffer, but then tstc ends up believing nothing is in
the buffer anyway because upriv->rd_ptr == upriv->wr_ptr.

A better approach is to let the indices be free-running, and only
reduce them modulo the buffer size when accessing the array. Then
"empty" is head-tail==0 and "full" is head-tail==size. This does rely
on the buffer size being a power-of-two and the free-running
indices simply wrapping around to 0 when incremented beyond the
maximal positive value.

Incidentally, that change from signed to unsigned int also improves
code generation quite a bit: In C, (signed int)%(signed int) is
defined to have the sign of the dividend (so (-35) % 32 is -3, not
29), and hence despite the modulus being a power-of-two, x % 32 does
not actually compile to the same as a simple x & 31 - on x86 with -Os,
it seems that gcc ends up emitting an idiv instruction, which is quite
expensive.

Signed-off-by: Rasmus Villemoes <ravi@prevas.dk>
Reviewed-by: Simon Glass <sjg@chromium.org>

Simon Glass <sjg@chromium.org> says:

When the SPL build-phase was first created it was designed to solve a
particular problem (the need to init SDRAM so that U-Boot proper could
be loaded). It has since expanded to become an important part of U-Boot,
with three phases now present: TPL, VPL and SPL

Due to this history, the term 'SPL' is used to mean both a particular
phase (the one before U-Boot proper) and all the non-proper phases.
This has become confusing.

For a similar reason CONFIG_SPL_BUILD is set to 'y' for all 'SPL'
phases, not just SPL. So code which can only be compiled for actual SPL,
for example, must use something like this:

   #if defined(CONFIG_SPL_BUILD) && !defined(CONFIG_TPL_BUILD)

In Makefiles we have similar issues. SPL_ has been used as a variable
which expands to either SPL_ or nothing, to chose between options like
CONFIG_BLK and CONFIG_SPL_BLK. When TPL appeared, a new SPL_TPL variable
was created which expanded to 'SPL_', 'TPL_' or nothing. Later it was
updated to support 'VPL_' as well.

This series starts a change in terminology and usage to resolve the
above issues:

- The word 'xPL' is used instead of 'SPL' to mean a non-proper build
- A new CONFIG_XPL_BUILD define indicates that the current build is an
  'xPL' build
- The existing CONFIG_SPL_BUILD is changed to mean SPL; it is not now
  defined for TPL and VPL phases
- The existing SPL_ Makefile variable is renamed to SPL_
- The existing SPL_TPL Makefile variable is renamed to PHASE_

It should be noted that xpl_phase() can generally be used instead of
the above CONFIGs without a code-space or run-time penalty.

This series does not attempt to convert all of U-Boot to use this new
terminology but it makes a start. In particular, renaming spl.h and
common/spl seems like a bridge too far at this point.

The series is fully bisectable. It has also been checked to ensure there
are no code-size changes on any commit.

Use PHASE_ as the symbol to select a particular XPL build. This means
that SPL_TPL_ is no-longer set.

Update the comment in bootstage to refer to this symbol, instead of
SPL_

Signed-off-by: Simon Glass <sjg@chromium.org>