[PATCH v2 4/8] dt-bindings: serial: Add support for selecting data transfer mode

Data transfer mode is fixed by TrustZone (TZ), which currently restricts
developers from modifying the transfer mode from the APPS side.

Document the 'qcom,xfer-mode' properties to select the data transfer mode,
either GPI DMA (Generic Packet Interface) or non-GPI mode (PIO/CPU DMA).

UART controller can operate in one of two modes based on the
'qcom,xfer-mode' property, and the firmware is loaded accordingly.

Co-developed-by: Mukesh Kumar Savaliya <redacted>
Signed-off-by: Mukesh Kumar Savaliya <redacted>
Signed-off-by: Viken Dadhaniya <redacted>
---

v1 -> v2:

- Drop 'qcom,load-firmware' property and add 'firmware-name' property in
  qup common driver.
- Update commit log.

v1 Link: https://lore.kernel.org/linux-kernel/20241204150326.1470749-4-quic_vdadhani@quicinc.com/ (local)
---
---
 .../devicetree/bindings/serial/qcom,serial-geni-qcom.yaml | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Documentation/devicetree/bindings/serial/qcom,serial-geni-qcom.yaml b/Documentation/devicetree/bindings/serial/qcom,serial-geni-qcom.yaml
index dd33794b3534..383773b32e47 100644
--- a/Documentation/devicetree/bindings/serial/qcom,serial-geni-qcom.yaml
+++ b/Documentation/devicetree/bindings/serial/qcom,serial-geni-qcom.yaml

@@ -56,6 +56,13 @@ properties:
   reg:
     maxItems: 1
 
+  qcom,xfer-mode:
+    description: Set the value to 1 for non-GPI (FIFO/CPU DMA) mode and 3 for GPI DMA mode.
+      The default mode is FIFO.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [1, 3]
+
+
 required:
   - compatible
   - clocks

@@ -82,5 +89,6 @@ examples:
         interconnects = <&qup_virt MASTER_QUP_CORE_0 0 &qup_virt SLAVE_QUP_CORE_0 0>,
                         <&gem_noc MASTER_APPSS_PROC 0 &config_noc SLAVE_QUP_0 0>;
         interconnect-names = "qup-core", "qup-config";
+        qcom,xfer-mode = <1>;
     };
 ...

-- 
2.34.1