rpi4: Add stdout-path to device tree ...

Some device tree users like to find a pointer to the standard serial
console in the device tree, in the "stdout-path" property of the /chosen
node.

Add the location of the Mini UART in that property, so that DT users are
happy, for instance Linux' earlycon detection.

Change-Id: I178e55016e5640de5ab0bc6e061944bd3583ea96
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

rpi4: Add GIC maintenance interrupt to GIC DT node ...

For being able to use the virtualisation support the GIC offers, we need
to know the interrupt number of the maintenance interrupt. This
information is missing from the official RPi4 device tree.

Use libfdt to add the "interrupts" property to the GIC node, which
allows hypervisors like KVM or Xen to be able to use the GIC's help on
virtualising interrupts.

Change-Id: Iab84f0885a5bf29fb84ca8f385e8a39d27700c75
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

rpi4: Cleanup memory regions, move pens to first page ...

Now that we have the SMP pens in the first page of DRAM, we can get rid
of all the fancy RPi3 memory regions that our RPi4 port does not really
need. This avoids using up memory all over the place, restricting ATF
to just run in the first 512KB of DRAM.

Remove the now unused regions. This also moves the SMP pens into our
first memory page (holding the firmware magic), where the original
firmware put them, but where there is also enough space for them.

Since the pens will require code execution privileges, we amend the
memory attributes used for that page to include write and execution
rights.

Change-Id: I131633abeb4a4d7b9057e737b9b0d163b73e47c6
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

rpi4: Reserve resident BL31 region from non-secure world ...

The GPU firmware loads the armstub8.bin (BL31) image at address 0, the
beginning of DRAM. As this holds the resident PSCI code and the SMP
pens, the non-secure world should better know about this, to avoid
accessing memory owned by TF-A. This is particularly criticial as the
Raspberry Pi 4 does not feature a secure memory controller, so
overwriting code is a very real danger.

Use the newly introduced function to add a node into reserved-memory
node, where non-secure world can check for regions to be excluded from
its mappings.

Reserve the first 512KB of memory for now. We can refine this later if
need be.

Change-Id: I00e55e70c5c02615320d79ff35bc32b805d30770
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

rpi4: Amend DTB to advertise PSCI ...

The device tree provided by the official Raspberry Pi firmware uses
spin tables for SMP bringup.

One of the benefit of having TF-A is that it provides PSCI services, so
let's rewrite the DTB to advertise PSCI instead of spin tables.
This uses the (newly exported) routine from the QEMU platform port.

Change-Id: Ifddcb14041ca253a333f8c2d5e97a42db152470c
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

rpi4: Determine BL33 entry point at runtime ...

Now that we have the armstub magic value in place, the GPU firmware will
write the kernel load address (and DTB address) into our special page,
so we can always easily access the actual location without hardcoding
any addresses into the BL31 image.

Make the compile-time defined PRELOADED_BL33_BASE macro optional, and
read the BL33 entry point from the magic location, if the macro was not
defined. We do the same for the DTB address.

This also splits the currently "common" definition of
plat_get_ns_image_entrypoint() to be separate between RPi3 and RPi4.

Change-Id: I6f26c0adc6fce2df47786b271c490928b4529abb
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

rpi4: Accommodate "armstub8.bin" header at the beginning of BL31 image ...

The Raspberry Pi GPU firmware checks for a magic value at offset 240
(0xf0) of the armstub8.bin image it loads. If that value matches,
it writes the kernel load address and the DTB address into subsequent
memory locations.
We can use these addresses to avoid hardcoding these values into the BL31
image, to make it more flexible and a drop-in replacement for the
official armstub8.bin.

Reserving just 16 bytes at offset 240 of the final image file is not easily
possible, though, as this location is in the middle of the generic BL31
entry point code.
However we can prepend an extra section before the actual BL31 image, to
contain the magic and addresses. This needs to be 4KB, because the
actual BL31 entry point needs to be page aligned.

Use the platform linker script hook that the generic code provides, to
add an almost empty 4KB code block before the entry point code. The very
first word contains a branch instruction to jump over this page, into
the actual entry code.
This also gives us plenty of room for the SMP pens later.

Change-Id: I38caa5e7195fa39cbef8600933a03d86f09263d6
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

Add basic support for Raspberry Pi 4 ...

The Raspberry Pi 4 is a single board computer with four Cortex-A72
cores. From a TF-A perspective it is quite similar to the Raspberry Pi
3, although it comes with more memory (up to 4GB) and has a GIC.

This initial port though differs quite a lot from the existing rpi3
platform port, mainly due to taking a much simpler and more robust
approach to loading the non-secure payload:
The GPU firmware of the SoC, which is responsible for initial platform
setup (including DRAM initialisation), already loads the kernel, device
tree and the "armstub" into DRAM. We take advantage of this, by placing
just a BL31 component into the armstub8.bin component, which will be
executed first, in AArch64 EL3.
The non-secure payload can be a kernel or a boot loader (U-Boot or
EDK-2), disguised as the "kernel" image and loaded by the GPU firmware.

So this is just a BL31-only port, which directly drops into EL2
and executes whatever has been loaded as the "kernel" image, handing
over the DTB address in x0.

Change-Id: I636f4d1f661821566ad9e341d69ba36f6bbfb546
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

rpi3: Allow runtime determination of UART base clock rate ...

At the moment the UART input clock rate is hard coded at compile time.
This works as long as the GPU firmware always sets up the same rate,
which does not seem to be true for the Raspberry Pi 4.

In preparation for being able to change this at runtime, add a base
clock parameter to the console setup function. This is still hardcoded
for the Raspberry Pi 3.

Change-Id: I398bc2f1e9b46f7af9a84cb0b33cbe8e78f2d900
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

rpi3: Do prescaler and control setup in C ...

To initialise the arch timer configuration and some clock prescaler, we
need to do two MMIO access *once*, early during boot.

As tempting as it may sound, plat_reset_handler() is not the right place
to do this, as it will be called on every CPU coming up, both for
secondary cores as well as during warmboots. So this access will be done
multiple times, and even during a rich OS' runtime. Whether doing so anyway
is actually harmful is hard to say, but we should definitely avoid this if
possible.

Move the initialisation of these registers to C code in
bl1_early_platform_setup(), where it will still be executed early enough
(before enabling the console), but only once during the whole boot
process.

Change-Id: I081c41a5476d424411411488ff8f633e87d3bcc5
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

rpi3: Prepare for supporting a GIC (in RPi4) ...

As the PSCI "power" management functions for the Raspberry Pi 3 port
will be shared with the upcoming RPi4 support, we need to prepare them
for dealing with the GIC interrupt controller.
Splitting this code just for those simple calls to the generic GIC
routines does not seem worthwhile, so just use a #define the protect the
GIC code from being included by the existing RPi3 code.

Change-Id: Iaca6b0214563852b28ad4a088ec45348ae8be40d
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

rpi3: Make SHARED_RAM optional ...

The existing Raspberry Pi 3 port sports a number of memory regions,
which are used for several purposes. The upcoming RPi4 port will not use
all of those, so make the SHARED_RAM region optional, by only mapping it
if it has actually been defined. This helps to get a cleaner RPi4 port.

Change-Id: Id69677b7fb6ed48d9f238854b610896785db8cab
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

rpi3: Rename RPI3_IO_BASE to RPI_IO_BASE ...

The location of the MMIO window is different between a Raspberry Pi 3
and 4: the former has it just below 1GB, the latter below 4GB.
The relative location of the peripherals is mostly compatible though.

To allow sharing code between the two models, let's rename the symbol
used for the MMIO base to the more generic RPI_IO_BASE name.

Change-Id: I3c2762fb30fd56cca743348e79d72ef8c60ddb03
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

rpi3: Move shared rpi3 files into common directory ...

To be able to share code more easily between the existing Raspberry Pi 3
and the upcoming Raspberry Pi 4 platform, move some code which is not
board specific into a "common" directory.

Change-Id: I9211ab2d754b040128fac13c2f0a30a5cc8c7f2c
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

rpi3: Move rng driver to drivers ...

To allow sharing the driver between the RPi3 and RPi4, move the random
number generator driver into the generic driver directory.

Change-Id: Iae94d7cb22c6bce3af9bff709d76d4caf87b14d1
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

rpi3: Move VC mailbox driver into generic drivers directory ...

To allow sharing the driver between the RPi3 and RPi4, move the mailbox
driver into the generic driver directory.

Change-Id: I463e49acf82b02bf004f3d56482b7791f3020bc0
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

rpi3: Move rpi3_hw.h header file to include/rpi_hw.h ...

With the advent of Raspberry Pi 4 support, we need to separate some
board specific headers between the RPi3 and RPi4.
Rename and move the "rpi3_hw.h" header, so that .c files just include
rpi_hw.h, and automatically get the correct version.

Change-Id: I03b39063028d2bee1429bffccde71dddfe2dcde8
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

rpi3: Add "rpi" platform directory ...

With the incoming support for the Raspberry Pi 4 boards, one directory
to serve both versions will not end up well.

Create an additional layer by inserting a "rpi" directory betweeen /plat
and rpi3, so that we can more easily share or separate files between the
two later.

Change-Id: I75adbb054fe7902f34db0fd5e579a55612dd8a5f
Signed-off-by: Andre Przywara <andre.przywara@arm.com>