On Mon, 21 Aug 2023 15:42:58 -0500
Rob Herring [off-list ref] wrote:

On Fri, Aug 18, 2023 at 06:39:00PM +0200, Christophe Leroy wrote:

quoted

From: Herve Codina <herve.codina@bootlin.com>

The QMC (QUICC mutichannel controller) is a controller present in some
PowerQUICC SoC such as MPC885.
The QMC HDLC uses the QMC controller to transfer HDLC data.

Additionally, a framer can be connected to the QMC HDLC.
If present, this framer is the interface between the TDM bus used by the
QMC HDLC and the E1/T1 line.
The QMC HDLC can use this framer to get information about the E1/T1 line
and configure the E1/T1 line.

Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Signed-off-by: Christophe Leroy <redacted>
---
 .../devicetree/bindings/net/fsl,qmc-hdlc.yaml | 46 +++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/fsl,qmc-hdlc.yaml

diff --git a/Documentation/devicetree/bindings/net/fsl,qmc-hdlc.yaml b/Documentation/devicetree/bindings/net/fsl,qmc-hdlc.yaml
new file mode 100644
index 000000000000..13f3572f0feb
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/fsl,qmc-hdlc.yaml

@@ -0,0 +1,46 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/fsl,qmc-hdlc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Freescale/NXP QUICC Multichannel Controller (QMC) HDLC
+
+maintainers:
+  - Herve Codina <herve.codina@bootlin.com>
+
+description: |  

Don't need '|'

Will be fixed in the next iteration.

quoted

+  The QMC HDLC uses a QMC (QUICC Multichannel Controller) channel to transfer
+  HDLC data.
+
+properties:
+  compatible:
+    const: fsl,qmc-hdlc
+
+  fsl,qmc-chan:
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    items:
+      - items:
+          - description: phandle to QMC node
+          - description: Channel number
+    description:
+      Should be a phandle/number pair. The phandle to QMC node and the QMC
+      channel to use.
+
+  framer:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description:
+      phandle to the framer node  

What's the framer? 

A framer is a component in charge of an E1/T1 line interface.
Is is connected to the TDM bus and it converts TDM frames to/from E1/T1
frames.
The HDLC data are sent/received to/from the TDM bus and the framer is used to
get information about the E1/T1 line such as link up/down.

I can update the description to:

--- 8< ---

phandle to the framer node. The framer is in charge of an E1/T1 line
interface connected to the TDM bus. It can be used to get the E1/T1 line
status such as link up/down.

--- 8< ---

Is that better ?

quoted

+
+required:
+  - compatible
+  - fsl,qmc-chan
+
+additionalProperties: false
+
+examples:
+  - |
+    hdlc {
+        compatible = "fsl,qmc-hdlc";
+        fsl,qmc-chan = <&qmc 16>;  

Where does this node live?

QMC is this[1]? Why don't you just add the compatible to channel@10 in 
the QMC node?

Indeed, I will move the properties (compatible and framer phandle) to the
QMC channel node.

Rob

[1] Documentation/devicetree/bindings/soc/fsl/cpm_qe/fsl,cpm1-scc-qmc.yaml

Best regards,
Hervé

-- 
Hervé Codina, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com