[PATCH v4] dt-bindings: remoteproc: qcom,shikra-pas: Allow bam-dmux subnode

[Vishnu Santhosh]

The Shikra modem uses BAM-DMUX for its WWAN data path, but the
qcom,shikra-pas remoteproc binding has no way to describe that
modem-owned child device.

Without a bam-dmux child node, the binding cannot model the relationship
between BAM-DMUX and the modem remoteproc, and userspace cannot
associate the multiplexer with the correct remoteproc instance.

Add an optional bam-dmux subnode to qcom,shikra-mpss-pas referencing
qcom,bam-dmux.yaml, and restrict it to the MPSS compatible since only
the modem subsystem uses BAM-DMUX. Add a second example exercising the
new subnode for dt_binding_check.

Co-developed-by: Deepak Kumar Singh <deepak.singh@xxxxxxxxxxxxxxxx>
Signed-off-by: Deepak Kumar Singh <deepak.singh@xxxxxxxxxxxxxxxx>
Signed-off-by: Vishnu Santhosh <vishnu.santhosh@xxxxxxxxxxxxxxxx>
---
Changes in v4:
- Reword the commit message to explain why BAM-DMUX belongs under the modem remoteproc.
- Restore the original CDSP example and add a separate MPSS example that exercises the new bam-dmux subnode.
- Link to v3: https://lore.kernel.org/r/20260813-shikra-pas-bam-dmux-binding-v3-1-167a3fb50d21@xxxxxxxxxxxxxxxx

Changes in v3:
- Reword commit message to keep it scoped to the binding change. 
- Retarget the example to qcom,shikra-mpss-pas and add a bam-dmux child.
- Link to v2: https://lore.kernel.org/r/20260729-shikra-pas-bam-dmux-binding-v2-1-d85fea84c141@xxxxxxxxxxxxxxxx

Changes in v2:
- Restrict bam-dmux to the qcom,shikra-mpss-pas compatible.
- Link to v1: https://lore.kernel.org/r/20260727-shikra-pas-bam-dmux-binding-v1-1-c0159c7c3ed4@xxxxxxxxxxxxxxxx
---
 .../bindings/remoteproc/qcom,shikra-pas.yaml       | 75 ++++++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/Documentation/devicetree/bindings/remoteproc/qcom,shikra-pas.yaml b/Documentation/devicetree/bindings/remoteproc/qcom,shikra-pas.yaml
index 253b14eb2b598f0ca91854c8ff4d0b785090e621..da66034311522ba36d160959172c1444c5999509 100644
--- a/Documentation/devicetree/bindings/remoteproc/qcom,shikra-pas.yaml
+++ b/Documentation/devicetree/bindings/remoteproc/qcom,shikra-pas.yaml
@@ -44,6 +44,11 @@ properties:
       - description: Firmware name of the Hexagon core
       - description: Firmware name of the Hexagon Devicetree
 
+  bam-dmux:
+    $ref: /schemas/net/qcom,bam-dmux.yaml#
+    description:
+      Qualcomm BAM Data Multiplexer (provides network interface to the modem)
+
   glink-edge:
     $ref: /schemas/remoteproc/qcom,glink-edge.yaml#
     description:
@@ -117,6 +122,16 @@ allOf:
         power-domains: false
         power-domain-names: false
 
+  - if:
+      properties:
+        compatible:
+          enum:
+            - qcom,shikra-cdsp-pas
+            - qcom,shikra-lpaicp-pas
+    then:
+      properties:
+        bam-dmux: false
+
 unevaluatedProperties: false
 
 examples:
@@ -165,3 +180,63 @@ examples:
             label = "cdsp";
         };
     };
+
+  - |
+    #include <dt-bindings/clock/qcom,rpmcc.h>
+    #include <dt-bindings/interconnect/qcom,icc.h>
+    #include <dt-bindings/interconnect/qcom,rpm-icc.h>
+    #include <dt-bindings/interconnect/qcom,shikra.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/power/qcom-rpmpd.h>
+
+    remoteproc@6080000 {
+        compatible = "qcom,shikra-mpss-pas";
+        reg = <0x06080000 0x100>;
+
+        interrupts-extended = <&intc GIC_SPI 307 IRQ_TYPE_EDGE_RISING>,
+                              <&modem_smp2p_in 0 IRQ_TYPE_EDGE_RISING>,
+                              <&modem_smp2p_in 1 IRQ_TYPE_EDGE_RISING>,
+                              <&modem_smp2p_in 2 IRQ_TYPE_EDGE_RISING>,
+                              <&modem_smp2p_in 3 IRQ_TYPE_EDGE_RISING>,
+                              <&modem_smp2p_in 7 IRQ_TYPE_EDGE_RISING>;
+        interrupt-names = "wdog", "fatal", "ready",
+                          "handover", "stop-ack", "shutdown-ack";
+
+        clocks = <&rpmcc RPM_SMD_XO_CLK_SRC>;
+        clock-names = "xo";
+
+        interconnects = <&mem_noc MASTER_AMPSS_M0 RPM_ALWAYS_TAG
+                         &mc_virt SLAVE_EBI_CH0 RPM_ALWAYS_TAG>;
+
+        power-domains = <&rpmpd RPMHPD_CX>;
+        power-domain-names = "cx";
+
+        memory-region = <&mpss_wlan_mem>;
+
+        qcom,smem-states = <&modem_smp2p_out 0>;
+        qcom,smem-state-names = "stop";
+
+        firmware-name = "qcom/shikra/modem.mbn";
+
+        glink-edge {
+            interrupts = <GIC_SPI 68 IRQ_TYPE_EDGE_RISING>;
+            mboxes = <&apcs_glb 12>;
+            qcom,remote-pid = <1>;
+            label = "mpss";
+        };
+
+        bam-dmux {
+            compatible = "qcom,bam-dmux";
+
+            interrupt-parent = <&modem_smsm>;
+            interrupts = <1 IRQ_TYPE_EDGE_BOTH>, <11 IRQ_TYPE_EDGE_BOTH>;
+            interrupt-names = "pc", "pc-ack";
+
+            qcom,smem-states = <&apps_smsm 1>, <&apps_smsm 11>;
+            qcom,smem-state-names = "pc", "pc-ack";
+
+            dmas = <&bam_dmux_dma 4>, <&bam_dmux_dma 5>;
+            dma-names = "tx", "rx";
+        };
+    };

---
base-commit: 3d6d817622b0a9721e3cc404df3469171582be13
change-id: 20260727-shikra-pas-bam-dmux-binding-28a6bf97857c

Best regards,
-- 
Vishnu Santhosh <vishnu.santhosh@xxxxxxxxxxxxxxxx>