libplatsupport,CMake: Check platsupport helpers

This commit adds a check to see if the path to the helpers is not
NULL/empty before including the helpers. As the comment in the commit
mentions, this is a hack to allow builds to be green before a more
suitable fix can be made to the older projects.

libplatsupport: Add tools to gen device headers

The new functions allow the user to input a YAML file that contains a
list of sub-devices of a particular device (GPIO pins, clocks on a
board etc), and output a C header '#define' enumeration.

libplatsupport: fix previous reverts

Due to my messing up of changelists, the revert
did not go through as cleanly as I'd hoped.

This commit reinstates
"libplatsupport: riscv plic irqchip parser"
23092562396ae9209679c83d75d25a953b70c2c6
and picks changes necessary from
"libplatsupport: hifive ltimer refactor"
c0c8ddcfac95a09b50e82cfa88367145d7aeaa5e
in order to build
"libplatsupport: refactor more timers"
ef1dfb7da52b8324281ee6999951bf603d44bdd7

Revert "libplatsupport: riscv plic irqchip parser"

This reverts commit 23092562396ae9209679c83d75d25a953b70c2c6.

Revert "libplatsupport: hifive ltimer refactor"

This reverts commit c0c8ddcfac95a09b50e82cfa88367145d7aeaa5e.

libplatsupport: hifive ltimer refactor

- Introduce two new helper functions
`helper_fdt_alloc_simple`, `create_ltimer_simple`
These are only used when there's 1 reg and 1 irq
to register.
- Refactor hifive timers to use these helper functions.
- Nit: init time_h explicitly instead of being calloc'd

libplatsupport: riscv plic irqchip parser

Add irqchip parser for riscv plic.

libplatsupport: omap3 irqchip parser

The IRQ numbers are a direct mapping so just based off of avic.c.

CMake: Add generic ltimer srcs for qemu-arm-virt

The qemu-arm-virt platform does not have an exclusive hardware timer but
instead uses the per-core ARM timer.

libplatsupport: Add FSL AVIC IRQ chip parser

This parser is compatible with some of the IRQ chips found on the older
Freescale SoCs like the i.MX31.

libplatsupport: Add GICv3 IRQ chip parser

This new parser module is able to parse interrupts under the format
specified by the GICv3 bindings. For now, the parser is only able to
parse SPI interrupts and not PPI interrupts.

platsupport: Remove weak subsystem init symbols

Having the clock and mux subsystem initialisation functions be a weak
symbol presents a number of problems. One of these problems is that the
linker may stop looking for other suitable symbols in other external
libraries.

tx2: Remove clock driver

Since the tx2 clock driver is heavily reliant on the libtx2bpmp library
in project_libs, we remove the tx2 clock driver from this repository and
place it into libplatsupportports in the project_libs library.

CMake: Link libtx2bpmp for the tx2

This library is used by the TX2 clock driver to communicate with the
BPMP co-processor to manipulate the clocks.

imx8m: Add a basic clock driver skeleton

This clock driver does not do anything at the moment, it is only here to
allow the libethdrivers to build for the imx8mq.

libplatsupport: Add Tegra IRQ controller parser

This commit adds in an additional IRQ controller parser module for the
Tegra interrupt controllers.

trivial: style changed files

libplatsupport: CMake: Link the ARM GIC module

This commit adds link options to CMake so that the ARM GIC parser module
can be linked even if it is not being used explicitly.

Added initial i.MX8M Mini EVK Platform support

This adds enough to use gpts and serial for sel4test

replace kernel_autoconf with sel4_autoconf

since the mainline kernel's kernel_autoconf doesn't include
seL4/gen_config.h but sel4_autoconf does

util_libs: remove autoconf.h from util_libs

this commit removes autoconf.h generation from each lib and
append '#include <<lib_name>/gen_config.h>' after each
'#include <autoconf.h>' since autoconf.h is only the for the
kernel config now. This is a temporarily solution, since we
currently don't have a way to tell which header files each file
is trying to include when it includes 'autoconf.h'

platsupport: aarch32 include for arm-hyp

Updated the sel4_arch_include to account for arm-hyp. In this case
we want to use the aarch32 includes.

trivial: style changed files

platsupport: add generic timer ltimer

Add an ltimer backed by the arm generic timer. For use for
debugging/testing/benchmarking when CONFIG_EXPORT_PCNT_USER is set.

platsupport: extend generic timer implementation

- update generic timer implementation to work on aarch64 in addition to
aarch32.
- add more manipulation functions for using the generic timer when it is
exported to user level.

Note that exporting the generic timer to user level exposes a timing
channel. This should only be done for testing and benchmarking and never
in a verified configuration of the kernel.

Added initial i.MX8M Quad EVK Platform support

This adds enough to use gpts and serial for sel4test

libplatsupport: Select imx mach drivers by plat

The mach folders contain shared drivers for all platforms with the same
"KernelArmMach" type. Making subdirectories allows for more fine grained
control of source file includes to handle situations when one or more
platforms don't use the shared devices but are still of the same mach.

trivial: style CMakeLists.txt

platsupport: Refactored exynos pll_get_freq

Updated the implementation of _pll_get_freq. This differs based
on the exynos SoC, Exynos5422 in particular. The implemenation
of get_freq has been moved out into different source files. These
source files are conditionally compiled in depending on the
target SoC.

Add CMake build rules for various libraries