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This adds a basic PSCI implementation allow secondary CPUs to be
released from an initial state and continue through to the warm boot
entrypoint.

Each secondary CPU is kept in a holding pen, whereby it polls the value
representing its hold state, by reading this from an array that acts as
a table for all the PEs. The hold states are initially set to 0 for all
cores to indicate that the executing core should continue polling.
To prevent the secondary CPUs from interfering with the platform's
initialization, they are only updated by the primary CPU once the cold
boot sequence has completed and fpga_pwr_domain_on(mpidr) is called.
The polling target CPU will then read 1 (which indicates that it should
branch to the warm reset entrypoint) and then jump to that address
rather than continue polling.

In addition to the initial polling behaviour of the secondary CPUs
before their warm boot reset sequence, they are also placed in a
low-power wfe() state at the end of each poll; accordingly, the PSCI
fpga_pwr_domain_on(mpidr) function also signals an event to all cores
(after updating the target CPU's hold entry) to wake them from this
state, allowing any secondary CPUs that are still polling to check
their hold state again.
This method is in accordance with both the PSCI and Linux kernel
recommendations, as the lessened overhead reduces the energy
consumption associated with the busy-loop.

The table of hold entries is implemented by a global array as shared SRAM
(which is used by other platforms in similar implementations) is not
available on the FPGA images.
Signed-off-by: Oliver Swede <oli.swede@arm.com>
Change-Id: I65cfd1892f8be1dfcb285f0e1e94e7a9870cdf5a

This makes use of the PRELOADED_BL33_BASE flag to indicate to BL31 that
the BL33 payload (kernel) has already been loaded and resides in memory;
BL31 will then jump to the non-secure address.

For this port the BL33 payload is the Linux kernel, and in accordance
with the pre-kernel setup requirements (as specified in the `Booting
AArch64 Linux' documentation:
https://www.kernel.org/doc/Documentation/arm64/booting.txt

),
this change also sets up the primary CPU's registers x0-x3 so they are
the expected values, which includes the address of the DTB at x0.

An external linker script is currently required to combine BL31, the
BL33 payload, and any other software images to create an ELF file that
can be uploaded to the FPGA board along with the bit file. It therefore
has dependencies on the value of PRELOADED_BL33_BASE (kernel base) and
the DTB base (plus any other relevant base addresses used to
distinguish the different ELF sections), both of which are set in this
patch.
Signed-off-by: Oliver Swede <oli.swede@arm.com>
Change-Id: If7ae8ee82d1e09fb05f553f6077ae13680dbf66b

This adds the minimal functions and definitions to create a basic
BL31 port for an initial FPGA image, in order for the port to be
uploaded to one the FPGA boards operated by an internal group within
Arm, such that BL31 runs as a payload for an image.

Future changes will enable the port for a wide range of system
configurations running on the FPGA boards to ensure compatibility with
multiple FPGA images.

It is expected that this will replace the FPGA fork of the Linux kernel
bootwrapper by performing similar secure-world initialization and setup
through the use of drivers and other well-established methods, before
passing control to the kernel, which will act as the BL33 payload and
run in EL2NS.

This change introduces a basic, loadable port with the console
initialized by setting the baud rate and base address of the UART as
configured by the Zeus image.

It is a BL31-only port, and RESET_TO_BL31 is enabled to reflect this.
Signed-off-by: Oliver Swede <oli.swede@arm.com>
Change-Id: I1817ad81be00afddcdbbda1ab70eb697203178e2