The Raspberry Pi has two different UART devices pin-muxed to GPIO 14&15:
One ARM PL011 one and the 8250 compatible "Mini-UART".
A dtoverlay parameter in config.txt will tell the firmware to switch
between the two: it will setup the right clocks and will configure the
pinmuxes accordingly.

To autodetect the user's choice, we read the pinmux register and check
its setting: ALT5 (0x2) means the Mini-UART is used, ALT0 (0x4) points
to the PL011.
Based on that we select the UART driver to initialise.

This will allow console output in any case.

Change-Id: I620d3ce68de6c6576599f2a405636020e1fd1376
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

The Broadcom 283x SoCs feature multiple UARTs: the mostly used
"Mini-UART", which is an 8250 compatible IP, and at least one PL011.
While the 8250 is usually used for serial console purposes, it suffers
from a design flaw, where its clock depends on the VPU clock, which can
change at runtime. This will reliably mess up the baud rate.
To avoid this problem, people might choose to use the PL011 UART for
the serial console, which is pin-mux'ed to the very same GPIO pins.
This can be done by adding "miniuart-bt" to the "dtoverlay=" line in
config.txt.

To prepare for this situation, use the newly gained freedom of sharing
one console_t pointer across different UART drivers, to introduce the
option of choosing the PL011 for the console.

This is for now hard-coded to choose the Mini-UART by default.
A follow-up patch will introduce automatic detection.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Change-Id: I8cf2522151e09ff4ff94a6d396aec6fc4b091a05

In the wake of the upcoming unification of the console setup code
between RPi3 and RPi4, extend the "clock-less" setup scheme to the
RPi3. This avoid programming any clocks or baud rate registers,
which makes the port more robust against GPU firmware changes.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Change-Id: Ida83a963bb18a878997e9cbd55f8ceac6a2e1c1f

Since now the generic console_t structure holds the UART base address as
well, let's use that generic location and drop the UART driver specific
data structure at all.

Change-Id: I5c2fe3b6a667acf80c808cfec4a64059a2c9c25f
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

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>

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>

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>

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>