dt-bindings: remoteproc: Add Qualcomm RPM processor/subsystem

On Qualcomm platforms, most subsystems (e.g. audio/modem DSP) are
described as remote processors in the device tree, with a dedicated
node where properties and services related to them can be described.

The Resource Power Manager (RPM) is also such a subsystem, with a
remote processor that is running a special firmware. Unfortunately,
the RPM never got a dedicated node representing it properly in the
device tree. Most of the RPM services are described below a top-level
/smd or /rpm-glink node.

However, SMD/GLINK is just one of the communication channels to the RPM
firmware. For example, the MPM interrupt functionality provided by the
RPM does not use SMD/GLINK but writes directly to a special memory
region allocated by the RPM firmware in combination with a mailbox.
Currently there is no good place in the device tree to describe this
functionality. It doesn't belong below SMD/GLINK but it's not an
independent top-level device either.

Introduce a new "qcom,rpm-proc" compatible that allows describing the
RPM as a remote processor/subsystem like all others. The SMD/GLINK node
is moved to a "smd-edge"/"glink-edge" subnode consistent with other
existing bindings. Additional subnodes (e.g. interrupt-controller for
MPM, rpm-master-stats) can be also added there.

Deprecate using the old top-level /smd node since all SMD edges
are now specified as subnodes of the remote processor.

Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230531-rpm-rproc-v3-6-a07dcdefd918@gerhold.net
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

2 files changed, 10 insertions, 3 deletions

diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom,smd-rpm.yaml b/Documentation/devicetree/bindings/soc/qcom/qcom,smd-rpm.yaml
index c6930706bfa9..2fa725b8af5d 100644
--- a/Documentation/devicetree/bindings/soc/qcom/qcom,smd-rpm.yaml
+++ b/Documentation/devicetree/bindings/soc/qcom/qcom,smd-rpm.yaml
@@ -120,10 +120,10 @@ examples:
     #include <dt-bindings/interrupt-controller/arm-gic.h>
     #include <dt-bindings/interrupt-controller/irq.h>
 
-    smd {
-        compatible = "qcom,smd";
+    remoteproc {
+        compatible = "qcom,msm8916-rpm-proc", "qcom,rpm-proc";
 
-        rpm {
+        smd-edge {
             interrupts = <GIC_SPI 168 IRQ_TYPE_EDGE_RISING>;
             qcom,ipc = <&apcs 8 0>;
             qcom,smd-edge = <15>;
diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom,smd.yaml b/Documentation/devicetree/bindings/soc/qcom/qcom,smd.yaml
index 063e595c12f7..4819ce90d206 100644
--- a/Documentation/devicetree/bindings/soc/qcom/qcom,smd.yaml
+++ b/Documentation/devicetree/bindings/soc/qcom/qcom,smd.yaml
@@ -15,6 +15,12 @@ description:
   The Qualcomm Shared Memory Driver is a FIFO based communication channel for
   sending data between the various subsystems in Qualcomm platforms.
 
+  Using the top-level SMD node is deprecated. Instead, the SMD edges are defined
+  directly below the device node representing the respective remote subsystem
+  or remote processor.
+
+deprecated: true
+
 properties:
   compatible:
     const: qcom,smd
@@ -37,6 +43,7 @@ examples:
   # The following example represents a smd node, with one edge representing the
   # "rpm" subsystem. For the "rpm" subsystem we have a device tied to the
   # "rpm_request" channel.
+  # NOTE: This is deprecated, represent the RPM using "qcom,rpm-proc" instead.
   - |
     #include <dt-bindings/interrupt-controller/arm-gic.h>