riscv: give dtb to kernel

- Pass the dtb that is loaded to the kernel.

Signed-off-by: Michael Yoo <Michael.Yoo@data61.csiro.au>

riscv: rename sptbr to satp

The sptbr register is renamed to satp in RISC-V privilege spec v1.10.

convert license headers to SPDX

Includes license review of 3rd-party files, adding missing upstream
headers, and moving the UNSW OZPLB license into its own file rather
than replicating it in the header.

elfloader: pick serial driver at runtime

On ARM, each serial driver now has an ELFLOADER_DRIVER(...), which
contains information about the compatible strings the driver
matches, the driver type and an "init" function for the driver to do
setup.

hardware_gen is now used by the ELF loader to generate a list of
interesting devices at compile-time, which go in a header file
"devices_gen.h".

The ELFLOADER_DRIVERs are put into a special "_driver_list" section
by the linker, and accessed as an array via the special
__start__driver_list and __stop__driver_list linker symbols.

At boot, the ELF loader calls initialise_devices(), which does the
following:
for each device in devices_gen.h
for each driver in elfloader_drivers array
if (device compat matches driver compat)
call driver->init(device, driver)
end if
end for
end for

For serial drivers, the serial driver calls uart_set_out with
the elfloader_device that should be the output for the elfloader
from the driver->init function.

There is a 'common' plat_console_putchar implementation which uses
the dynamically picked uart output. This eliminates the need
for a lot of the platform-specific code we have.

This implementation could one day be replaced with a in-ELF loader
device tree. This could also (possibly) be used to handle dynamically
picking SMP core bringup mechanisms.

As all RISC-V platforms use SBI to provide a serial port, RISCV is
only modified to register the SBI putc implementation as the fputc
implementatin.

elfloader: improve EFI support

Rather than using a bunch of assembly code to relocate the
ELF loader, we use gnu-efi[1] to build an EFI executable.
This approach handles things like nested structs better, by including
a "proper" way to handle ELF relocations.

[1]: https://sourceforge.net/projects/gnu-efi/

trivial: Fix typo

This fixes a typo that afb5f848 introduces.

trivial: Style changed files

elfloader: Prefer using the CPIO DTB if it exists

The elfloader will now prioritise passing through the DTB that's
included in the CPIO archive.

elfloader: Add SMP support for RISCV

elfloader-tool: Add fence.i before kernel start

This fence operation ensures that writes to memory that will be executed
are visible to the instruction stream.

elfloader-tool: explicitly link config libs

explicitly link kernel_autoconf and elfloader_Config
since the global config lib is going to be remove

RISCV: Moving platform files to arch

The SBI is defined in the RISCV spec that all platforms should follow.
Moving related files from plat to arch.

elfloader: pass DTB from bootloader to seL4 on ARM

On ARM, we expect the physical address of the dtb to be passed in r2 on
aarch32 or x0 on aarch64. RISC-V supplies a DTB in a1, but we currently
don't pass it to the kernel.

The elfloader then moves the dtb to immediately after where the
kernel is loaded in memory, and passes that address on to the kernel.

If there is no bootloader provided DTB, the elfloader will pass 0
to the kernel as the start address of the DTB.

RISCV: Map the elfloader to a separate page table on 64-bit machine.

trivial: style this repo

RISCV: Stop passing hartid and DTB to the seL4 kernel.

trivial: use BIT in riscv boot.c

riscv: Support 2 MiB kernel mappings in the elfloader

Change-Id: Iebdee033d7393a35b2a58cbae553c735bfc40f2f

riscv: clean up elfloader mappings.

Change-Id: Ic59e531e1e552d8fb663ff21b59b984f820c289a

riscv: Abstract kernel window mapping

This makes the kernel window mapping slightly more robust by not making assuptions
on the virtual address of the kernel, and instead using the virtual address
provided by the kernel image.

riscv: Remove unused variables

elfloader: Remove more deadcode

elfloader: Remove RISC-V multicore stubs

elfloader: Deduplicate a lot of arch-riscv/boot.c

elfloader: riscv init_kernel_t rename

riscv: Pass physical dtb address to the kernel

Passes the physical address of the dtb to the kernel instead of the null mapping.
Also document the lack of passing any dtb to secondary cores despite using the same
init_kernel_t entry point

riscv: Remove nonsense dtb mappings

This removes code that mappings the dtb at the NULL virtual address. It makes no sense
to map it here as it will cease to be available to the kernel the moment it activates
the actual kernel window.

elfloader RISC-V: Remove duplicate ELF code

elfloader: remove duplicate NULL definition

elfloader: Suppress RISC-V unused warning spam

riscv: fix licenses

- Add missing licenses
- NICTA -> DATA61

RISCV port