| Message ID | 20230404115026.2828149-2-cristian.marussi@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add SCMI support for mailbox unidirectional channels | expand |
On Tue, 04 Apr 2023 12:50:25 +0100, Cristian Marussi wrote: > SCMI defines two kinds of communication channels between the agent and the > platform: one bidirectional 'a2p' channel used by the agent to send SCMI > commands and synchronously receive the related replies, and an optional > 'p2a' unidirectional channel used to asynchronously receive delayed > responses and notifications emitted from the platform. > > When configuring an SCMI transport based on mailboxes, the current binding > supports only mailboxes providing bidirectional channels: in such a case > one mailbox channel can be easily assigned to each SCMI channel as above > described. > > In case, instead, to have to deal with mailboxes providing only distinct > unidirectional channels, it becomes necessary to extend the binding in > order to be able to bind 2 distinct unidirectional mailbox channels to the > same SCMI 'a2p' channel. > > Bidirectional and unidirectional channels support for the SCMI mailbox > transport can coexist by carefully considering the effective combination > of defined 'mboxes' and 'shmem' descriptors. > > Signed-off-by: Cristian Marussi <cristian.marussi@arm.com> > --- > Cc: Rob Herring <robh+dt@kernel.org> > Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org> > Cc: devicetree@vger.kernel.org > > v2 --> v3 > - coalesced oneOf entries using proper minItems > - removed unidirectional channels example > v1 --> v2 > - added mbox-names unidirectional definitions and example > --- > .../bindings/firmware/arm,scmi.yaml | 48 +++++++++++++++---- > 1 file changed, 38 insertions(+), 10 deletions(-) > Reviewed-by: Rob Herring <robh@kernel.org>
diff --git a/Documentation/devicetree/bindings/firmware/arm,scmi.yaml b/Documentation/devicetree/bindings/firmware/arm,scmi.yaml index 2f7c51c75e85..5824c43e9893 100644 --- a/Documentation/devicetree/bindings/firmware/arm,scmi.yaml +++ b/Documentation/devicetree/bindings/firmware/arm,scmi.yaml @@ -56,17 +56,38 @@ properties: description: Specifies the mailboxes used to communicate with SCMI compliant firmware. - items: - - const: tx - - const: rx + oneOf: + - items: + - const: tx + - const: rx + minItems: 1 + - items: + - const: tx + - const: tx_reply + - const: rx + minItems: 2 mboxes: description: List of phandle and mailbox channel specifiers. It should contain - exactly one or two mailboxes, one for transmitting messages("tx") - and another optional for receiving the notifications("rx") if supported. + exactly one, two or three mailboxes; the first one or two for transmitting + messages ("tx") and another optional ("rx") for receiving notifications + and delayed responses, if supported by the platform. + The number of mailboxes needed for transmitting messages depends on the + type of channels exposed by the specific underlying mailbox controller; + one single channel descriptor is enough if such channel is bidirectional, + while two channel descriptors are needed to represent the SCMI ("tx") + channel if the underlying mailbox channels are of unidirectional type. + The effective combination in numbers of mboxes and shmem descriptors let + the SCMI subsystem determine unambiguosly which type of SCMI channels are + made available by the underlying mailbox controller and how to use them. + 1 mbox / 1 shmem => SCMI TX over 1 mailbox bidirectional channel + 2 mbox / 2 shmem => SCMI TX and RX over 2 mailbox bidirectional channels + 2 mbox / 1 shmem => SCMI TX over 2 mailbox unidirectional channels + 3 mbox / 2 shmem => SCMI TX and RX over 3 mailbox unidirectional channels + Any other combination of mboxes and shmem is invalid. minItems: 1 - maxItems: 2 + maxItems: 3 shmem: description: @@ -228,13 +249,20 @@ $defs: maxItems: 1 mbox-names: - items: - - const: tx - - const: rx + oneOf: + - items: + - const: tx + - const: rx + minItems: 1 + - items: + - const: tx + - const: tx_reply + - const: rx + minItems: 2 mboxes: minItems: 1 - maxItems: 2 + maxItems: 3 shmem: minItems: 1
SCMI defines two kinds of communication channels between the agent and the platform: one bidirectional 'a2p' channel used by the agent to send SCMI commands and synchronously receive the related replies, and an optional 'p2a' unidirectional channel used to asynchronously receive delayed responses and notifications emitted from the platform. When configuring an SCMI transport based on mailboxes, the current binding supports only mailboxes providing bidirectional channels: in such a case one mailbox channel can be easily assigned to each SCMI channel as above described. In case, instead, to have to deal with mailboxes providing only distinct unidirectional channels, it becomes necessary to extend the binding in order to be able to bind 2 distinct unidirectional mailbox channels to the same SCMI 'a2p' channel. Bidirectional and unidirectional channels support for the SCMI mailbox transport can coexist by carefully considering the effective combination of defined 'mboxes' and 'shmem' descriptors. Signed-off-by: Cristian Marussi <cristian.marussi@arm.com> --- Cc: Rob Herring <robh+dt@kernel.org> Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org> Cc: devicetree@vger.kernel.org v2 --> v3 - coalesced oneOf entries using proper minItems - removed unidirectional channels example v1 --> v2 - added mbox-names unidirectional definitions and example --- .../bindings/firmware/arm,scmi.yaml | 48 +++++++++++++++---- 1 file changed, 38 insertions(+), 10 deletions(-)