On 23.09.20 22:54, Rob Herring wrote: > On Fri, Sep 18, 2020 at 06:55:58PM +0200, Peter Hilber wrote: >> From: Igor Skalkin <igor.skalkin@xxxxxxxxxxxxxxx> >> >> Document the properties for arm,scmi-virtio compatible nodes. The >> backing virtio SCMI device is described in patch [1]. >> >> [1] https://lists.oasis-open.org/archives/virtio-comment/202005/msg00096.html >> >> Co-developed-by: Peter Hilber <peter.hilber@xxxxxxxxxxxxxxx> >> Signed-off-by: Peter Hilber <peter.hilber@xxxxxxxxxxxxxxx> >> Signed-off-by: Igor Skalkin <igor.skalkin@xxxxxxxxxxxxxxx> >> --- >> .../devicetree/bindings/arm/arm,scmi.txt | 38 ++++++++++++++++++- >> 1 file changed, 36 insertions(+), 2 deletions(-) >> >> diff --git a/Documentation/devicetree/bindings/arm/arm,scmi.txt b/Documentation/devicetree/bindings/arm/arm,scmi.txt >> index 55deb68230eb..844ff3c40a49 100644 >> --- a/Documentation/devicetree/bindings/arm/arm,scmi.txt >> +++ b/Documentation/devicetree/bindings/arm/arm,scmi.txt >> @@ -13,6 +13,9 @@ the device tree. >> Required properties: >> >> The scmi node with the following properties shall be under the /firmware/ node. >> +Some properties are specific to a transport type. >> + >> +shmem-based transports (mailbox, smc/hvc): >> >> - compatible : shall be "arm,scmi" or "arm,scmi-smc" for smc/hvc transports >> - mboxes: List of phandle and mailbox channel specifiers. It should contain >> @@ -21,6 +24,17 @@ The scmi node with the following properties shall be under the /firmware/ node. >> supported. >> - shmem : List of phandle pointing to the shared memory(SHM) area as per >> generic mailbox client binding. >> + >> +Virtio transport: >> + >> +- compatible : shall be "arm,scmi-virtio". >> +- virtio_transport : phandle of the virtio device. This device must support one >> + virtqueue for transmitting commands ("tx", cmdq), and, >> + optionally, one more virtqueue for receiving notifications >> + and delayed responses ("rx", eventq). > > Isn't what the virtio device provides discoverable? We don't have virtio > protocols in DT for anything else. Why is SCMI special? > > Rob > Does your comment refer to the presence of the `virtio_transport' phandle, or to the entire "arm,scmi-virtio" node? The protocol child nodes of "arm,scmi-virtio" can be clock providers, power domain providers, etc. The author and me are currently looking into how to replace the `virtio_transport' phandle. Best regards, Peter
