mach-virt has existed for a while but it is not written down what it actually
consists of. Although it seems a bit unusual to document a binding for an
entire platform since mach-virt is entirely virtual it is helpful to have
something to refer to in the absence of a single concrete implementation.

I've done my best to capture the requirements based on the git log and my
memory/understanding.

While here remove the xenvm dts example, the Xen tools will now build a
suitable mach-virt compatible dts when launching the guest.

Signed-off-by: Ian Campbell <redacted>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Pawel Moll <redacted>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Kumar Gala <redacted>
Cc: Olof Johansson <redacted>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Marc Zyngier <redacted>
Cc: Will Deacon <redacted>
Cc: Stefano Stabellini <redacted>
Cc: devicetree at vger.kernel.org
Cc: linux-kernel at vger.kernel.org
Cc: linux-arm-kernel at lists.infradead.org
---
I'm not sure which tree this sort of thing should go though, sorry for the
huge Cc.
---
 .../devicetree/bindings/arm/mach-virt.txt          |   32 ++++++++
 arch/arm/boot/dts/xenvm-4.2.dts                    |   81 --------------------
 2 files changed, 32 insertions(+), 81 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/arm/mach-virt.txt
 delete mode 100644 arch/arm/boot/dts/xenvm-4.2.dts

diff --git a/Documentation/devicetree/bindings/arm/mach-virt.txt b/Documentation/devicetree/bindings/arm/mach-virt.txt
new file mode 100644
index 0000000..562bcda
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/mach-virt.txt

@@ -0,0 +1,32 @@
+* Mach-virt "Dummy Virtual Machine" platform
+
+"mach-virt" is the smallest, dumbest platform possible, to be used as
+a guest for Xen, KVM and other hypervisors. It has no
+properties/functionality of its own and is driven entirely by device
+tree.
+
+This document defines the requirements for such a platform.
+
+* Required properties:
+
+- compatible: should be one of:
+	"linux,dummy-virt"
+	"xen,xenvm"
+
+In addition to the standard nodes (chosen, cpus, memory etc) the
+platform is required to provide certain other basic functionality
+which must be described in the device tree:
+
+    The platform must provide an ARM Generic Interrupt Controller
+    (GIC), defined in Documentation/devicetree/bindings/arm/gic.txt.
+
+    The platform must provide ARM architected timer, defined in
+    Documentation/devicetree/bindings/arm/arch_timer.txt.
+
+    If the platform is SMP then it must provide the Power State
+    Coordination Interface (PSCI) described in
+    Documentation/devicetree/bindings/arm/psci.txt.