[v7,1/2] dt-bindings: misc: aspeed-p2a-ctrl: add support

Document the ast2400, ast2500 PCI-to-AHB bridge control driver bindings.

Signed-off-by: Patrick Venture <venture@google.com>
---
Changes for v7:
- Moved node under the syscon node it requires
Changes for v6:
- None
Changes for v5:
- None
Changes for v4:
- None
Changes for v3:
- None
Changes for v2:
- Added comment about syscon required parameter.
---
 .../bindings/misc/aspeed-p2a-ctrl.txt         | 48 +++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt

On Tue, Mar 12, 2019 at 11:30 AM Patrick Venture <venture@google.com> wrote:
>
> Document the ast2400, ast2500 PCI-to-AHB bridge control driver bindings.
>
> Signed-off-by: Patrick Venture <venture@google.com>
> ---
> Changes for v7:
> - Moved node under the syscon node it requires
> Changes for v6:
> - None
> Changes for v5:
> - None
> Changes for v4:
> - None
> Changes for v3:
> - None
> Changes for v2:
> - Added comment about syscon required parameter.
> ---
>  .../bindings/misc/aspeed-p2a-ctrl.txt         | 48 +++++++++++++++++++
>  1 file changed, 48 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
>
> diff --git a/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt b/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
> new file mode 100644
> index 000000000000..088cc4e3dc54
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
> @@ -0,0 +1,48 @@
> +======================================================================
> +Device tree bindings for Aspeed AST2400/AST2500 PCI-to-AHB Bridge Control Driver
> +======================================================================
> +
> +The bridge is available on platforms with the VGA enabled on the Aspeed device.
> +In this case, the host has access to a 64KiB window into all of the BMC's
> +memory.  The BMC can disable this bridge.  If the bridge is enabled, the host
> +has read access to all the regions of memory, however the host only has read
> +and write access depending on a register controlled by the BMC.
> +
> +Required properties:
> +===================
> +
> + - compatible: must be one of:
> +       - "aspeed,ast2400-p2a-ctrl"
> +       - "aspeed,ast2500-p2a-ctrl"
> +
> + - syscon: handle to syscon device node controlling PCI.
> +
> +Optional properties:
> +===================
> +
> +- memory-region: A phandle to a reserved_memory region to be used for the PCI
> +               to AHB mapping
> +
> +The p2a-control node should be the child of a syscon node with the required
> +property:
> +
> +- compatible : Should be one of the following:
> +               "aspeed,ast2400-scu", "syscon", "simple-mfd"
> +               "aspeed,g4-scu", "syscon", "simple-mfd"
> +               "aspeed,ast2500-scu", "syscon", "simple-mfd"
> +               "aspeed,g5-scu", "syscon", "simple-mfd"
> +
> +Example:
> +
> +g4 Example
> +----------
> +
> +syscon: scu@1e6e2000 {
> +       compatible = "aspeed,ast2400-scu", "syscon", "simple-mfd";
> +       reg = <0x1e6e2000 0x1a8>;
> +
> +       p2a: p2a-control {
> +               compatible = "aspeed,ast2400-p2a-ctrl";

If there's a defined register range, then you could add a reg property
(even though Linux doesn't use it).

Either way,

Reviewed-by: Rob Herring <robh@kernel.org>

On Wed, Mar 13, 2019 at 12:54 PM Rob Herring <robh+dt@kernel.org> wrote:
>
> On Tue, Mar 12, 2019 at 11:30 AM Patrick Venture <venture@google.com> wrote:
> >
> > Document the ast2400, ast2500 PCI-to-AHB bridge control driver bindings.
> >
> > Signed-off-by: Patrick Venture <venture@google.com>
> > ---
> > Changes for v7:
> > - Moved node under the syscon node it requires
> > Changes for v6:
> > - None
> > Changes for v5:
> > - None
> > Changes for v4:
> > - None
> > Changes for v3:
> > - None
> > Changes for v2:
> > - Added comment about syscon required parameter.
> > ---
> >  .../bindings/misc/aspeed-p2a-ctrl.txt         | 48 +++++++++++++++++++
> >  1 file changed, 48 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
> >
> > diff --git a/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt b/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
> > new file mode 100644
> > index 000000000000..088cc4e3dc54
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
> > @@ -0,0 +1,48 @@
> > +======================================================================
> > +Device tree bindings for Aspeed AST2400/AST2500 PCI-to-AHB Bridge Control Driver
> > +======================================================================
> > +
> > +The bridge is available on platforms with the VGA enabled on the Aspeed device.
> > +In this case, the host has access to a 64KiB window into all of the BMC's
> > +memory.  The BMC can disable this bridge.  If the bridge is enabled, the host
> > +has read access to all the regions of memory, however the host only has read
> > +and write access depending on a register controlled by the BMC.
> > +
> > +Required properties:
> > +===================
> > +
> > + - compatible: must be one of:
> > +       - "aspeed,ast2400-p2a-ctrl"
> > +       - "aspeed,ast2500-p2a-ctrl"
> > +
> > + - syscon: handle to syscon device node controlling PCI.
> > +
> > +Optional properties:
> > +===================
> > +
> > +- memory-region: A phandle to a reserved_memory region to be used for the PCI
> > +               to AHB mapping
> > +
> > +The p2a-control node should be the child of a syscon node with the required
> > +property:
> > +
> > +- compatible : Should be one of the following:
> > +               "aspeed,ast2400-scu", "syscon", "simple-mfd"
> > +               "aspeed,g4-scu", "syscon", "simple-mfd"
> > +               "aspeed,ast2500-scu", "syscon", "simple-mfd"
> > +               "aspeed,g5-scu", "syscon", "simple-mfd"
> > +
> > +Example:
> > +
> > +g4 Example
> > +----------
> > +
> > +syscon: scu@1e6e2000 {
> > +       compatible = "aspeed,ast2400-scu", "syscon", "simple-mfd";
> > +       reg = <0x1e6e2000 0x1a8>;
> > +
> > +       p2a: p2a-control {
> > +               compatible = "aspeed,ast2400-p2a-ctrl";
>
> If there's a defined register range, then you could add a reg property
> (even though Linux doesn't use it).

in this case, the device just needs access to two separate registers
controlled by the syscon to which it is now a child.

>
> Either way,
>
> Reviewed-by: Rob Herring <robh@kernel.org>