[v2] devicetree,xen: add xen,shared-memory binding

From: Stefano Stabellini <stefanos@xilinx.com>

Introduce a device tree binding for Xen reserved-memory regions. They
are used to share memory across VMs from the VM config files. (See
static_shm config option.)

Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
---
Changes in v2:
- fix Author line
- add versioning
- xen,id instead of id
---
 .../bindings/reserved-memory/xen,shared-memory.txt   | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reserved-memory/xen,shared-memory.txt

Hi Stefano,

On 18/10/2018 23:10, Stefano Stabellini wrote:
> From: Stefano Stabellini <stefanos@xilinx.com>
> 
> Introduce a device tree binding for Xen reserved-memory regions. They
> are used to share memory across VMs from the VM config files. (See
> static_shm config option.)
> 
> Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
> ---
> Changes in v2:
> - fix Author line
> - add versioning
> - xen,id instead of id
> ---
>   .../bindings/reserved-memory/xen,shared-memory.txt   | 20 ++++++++++++++++++++
>   1 file changed, 20 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/reserved-memory/xen,shared-memory.txt
> 
> diff --git a/Documentation/devicetree/bindings/reserved-memory/xen,shared-memory.txt b/Documentation/devicetree/bindings/reserved-memory/xen,shared-memory.txt
> new file mode 100644
> index 0000000..9078fb7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/reserved-memory/xen,shared-memory.txt
> @@ -0,0 +1,20 @@
> +* Xen hypervisor reserved-memory binding
> +
> +Expose one or more memory regions as reserved-memory to the guest
> +virtual machine. 
> Typically, a region is configured at VM creation time
> +to be a shared memory area across multiple virtual machines for
> +communication among them.
> +
> +For each of these pre-shared memory regions, a range is exposed under
> +the /reserved-memory node as a child node. Each range sub-node is named
> +xen-shmem@<address> and has the following properties:
> +
> +- compatible:
> +	compatible = "xen,shared-memory-v1", "xen,shared-memory"

Do we need to specify the two compatibles?

> +
> +- reg:
> +	the base guest physical address and size of the shared memory region
> +
> +- xen,id:
> +	a string that identifies the shared memory region as specified in
> +	the VM config file
>

On Mon, Oct 22, 2018 at 11:27:23AM +0100, Julien Grall wrote:
> Hi Stefano,
> 
> On 18/10/2018 23:10, Stefano Stabellini wrote:
> > From: Stefano Stabellini <stefanos@xilinx.com>
> > 
> > Introduce a device tree binding for Xen reserved-memory regions. They
> > are used to share memory across VMs from the VM config files. (See
> > static_shm config option.)
> > 
> > Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
> > ---
> > Changes in v2:
> > - fix Author line
> > - add versioning
> > - xen,id instead of id
> > ---
> >   .../bindings/reserved-memory/xen,shared-memory.txt   | 20 ++++++++++++++++++++
> >   1 file changed, 20 insertions(+)
> >   create mode 100644 Documentation/devicetree/bindings/reserved-memory/xen,shared-memory.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/reserved-memory/xen,shared-memory.txt b/Documentation/devicetree/bindings/reserved-memory/xen,shared-memory.txt
> > new file mode 100644
> > index 0000000..9078fb7
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/reserved-memory/xen,shared-memory.txt
> > @@ -0,0 +1,20 @@
> > +* Xen hypervisor reserved-memory binding
> > +
> > +Expose one or more memory regions as reserved-memory to the guest
> > +virtual machine. Typically, a region is configured at VM creation time
> > +to be a shared memory area across multiple virtual machines for
> > +communication among them.
> > +
> > +For each of these pre-shared memory regions, a range is exposed under
> > +the /reserved-memory node as a child node. Each range sub-node is named
> > +xen-shmem@<address> and has the following properties:
> > +
> > +- compatible:
> > +	compatible = "xen,shared-memory-v1", "xen,shared-memory"
> 
> Do we need to specify the two compatibles?

I'd just drop the fallback as version seems to be just in case.

Rob