system-arm: Refactor makefile to create targets with functions

This change simplifies writing targets which has same prefix but
differrent number of CPUs.

Change-Id: I3b7d67a554f5d27714ace6b88c9784ddaa3b34d5
Signed-off-by: Chun-Chen TK Hsu <chunchenhsu@google.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19989
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

system-arm: Fix dtsi dependencies in Makefile

Making vexpress_gem5_vX.dtsi depend on vexpress_gem5_vX_base.dtsi
does nothing, since vexpress_gem5_vX.dtsi is never built (much in
the same way as there is no point in making a C header depend on
another).

Fix that by making all the .dts depend on both .dtsi's.

Change-Id: I9131e0b1b2e521bb09d14721dec38bf6a2d98583
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Ciro Santilli <ciro.santilli@arm.com>
Reviewed-by: Ruben Ayrapetyan <ruben.ayrapetyan@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/16143
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

system-arm: Add device tree for new VExpress GEM5_V2 platform

Change-Id: Ifc2b91afe5b88a656b4ed1c64ab6cca97f082034
Reviewed-on: https://gem5-review.googlesource.com/c/14275
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

system-arm: Split the VExpress_GEM5_V1 base dts

With the introduction of the new DPU model, we need different
variations of the VExpress_GEM5_V1 platform. This splits the platform
dtsi file into a separate file for the base platform and the
HDLCD-based platform. This matches the hierarchy in RealView.py.

Change-Id: Id02380122655b5d3aa3548a703fdef178bba17d9
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Ciro Santilli <ciro.santilli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/11035
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>

arm, config: Add an example ARM big.LITTLE(tm) configuration script

An ARM big.LITTLE system consists of two cpu clusters: the big
CPUs are typically complex out-of-order cores and the little
CPUs are simpler in-order ones. The fs_bigLITTLE.py script
can run a full system simulation with various number of big
and little cores and cache hierarchy. The commit also includes
two example device tree files for booting Linux on the
bigLITTLE system.

Change-Id: I6396fb3b2d8f27049ccae49d8666d643b66c088b
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

arm: Ship Linux device trees with gem5

Ship aarch32 and aarch64 device trees with gem5. We currently ship
device trees as a part of the gem5 Linux kernel repository. This makes
tracking hard since device trees are supposed to be platform dependent
rather than kernel dependent (Linux considers device trees to be a
stable kernel ABI). It also makes code sharing between aarch32 and
aarch64 impossible.

This changeset implements a set of device trees for the new
VExpress_GEM5_V1 platform. The platform is described in a shared file
that is separate from the memory/CPU description. Due to differences
in how secondary CPUs are initialized, aarch32 and aarch64 use
different base files describing CPU nodes and the machine's
compatibility property.