fdt/wrappers: Replace fdtw_read_cells() implementation ...

Our fdtw_read_cells() implementation goes to great lengths to
sanity-check every parameter and result, but leaves a big hole open:
The size of the storage the value pointer points at needs to match the
number of cells given. This can't be easily checked at compile time,
since we lose the size information by using a void pointer.
Regardless the current usage of this function is somewhat wrong anyways,
since we use it on single-element, fixed-length properties only, for
which the DT binding specifies the size.
Typically we use those functions dealing with a number of cells in DT
context to deal with *dynamically* sized properties, which depend on
other properties (#size-cells, #clock-cells, ...), to specify the number
of cells needed.

Another problem with the current implementation is the use of
ambiguously sized types (uintptr_t, size_t) together with a certain
expectation about their size. In general there is no relation between
the length of a DT property and the bitness of the code that parses the
DTB: AArch64 code could encounter 32-bit addresses (where the physical
address space is limited to 4GB [1]), while AArch32 code could read
64-bit sized properties (/memory nodes on LPAE systems, [2]).

To make this more clear, fix the potential issues and also align more
with other DT users (Linux and U-Boot), introduce functions to explicitly
read uint32 and uint64 properties. As the other DT consumers, we do this
based on the generic "read array" function.
Convert all users to use either of those two new functions, and make
sure we never use a pointer to anything other than uint32_t or uint64_t
variables directly.

This reveals (and fixes) a bug in plat_spmd_manifest.c, where we write
4 bytes into a uint16_t variable (passed via a void pointer).

Also we change the implementation of the function to better align with
other libfdt users, by using the right types (fdt32_t) and common
variable names (*prop, prop_names).

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi#n874
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/ecx-2000.dts

Change-Id: I718de960515117ac7a3331a1b177d2ec224a3890
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

fconf: enhancements to firmware configuration framework ...

A populate() function essentially captures the value of a property,
defined by a platform, into a fconf related c structure. Such a
callback is usually platform specific and is associated to a specific
configuration source.
For example, a populate() function which captures the hardware topology
of the platform can only parse HW_CONFIG DTB. Hence each populator
function must be registered with a specific 'config_type' identifier.
It broadly represents a logical grouping of configuration properties
which is usually a device tree source file.

Example:
> TB_FW: properties related to trusted firmware such as IO policies,
	 base address of other DTBs, mbedtls heap info etc.
> HW_CONFIG: properties related to hardware configuration of the SoC
	 such as topology, GIC controller, PSCI hooks, CPU ID etc.

This patch modifies FCONF_REGISTER_POPULATOR macro and fconf_populate()
to register and invoke the appropriate callbacks selectively based on
configuration type.

Change-Id: I6f63b1fd7a8729c6c9137d5b63270af1857bb44a
Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>

fconf: Add dynamic config DTBs info as property ...

This patch introduces a better separation between the trusted-boot
related properties, and the dynamic configuration DTBs loading
information.

The dynamic configuration DTBs properties are moved to a new node:
`dtb-registry`. All the sub-nodes present will be provided to the
dynamic config framework to be loaded. The node currently only contains
the already defined configuration DTBs, but can be extended for future
features if necessary.
The dynamic config framework is modified to use the abstraction provided
by the fconf framework, instead of directly accessing the DTBs.

The trusted-boot properties are kept under the "arm,tb_fw" compatible
string, but in a separate `tb_fw-config` node.
The `tb_fw-config` property of the `dtb-registry` node simply points
to the load address of `fw_config`, as the `tb_fw-config` is currently
part of the same DTB.

Change-Id: Iceb6c4c2cb92b692b6e28dbdc9fb060f1c46de82
Signed-off-by: Louis Mayencourt <louis.mayencourt@arm.com>