Re: [alsa-devel] [RESEND PATCH v4 1/4] dt-bindings: soundwire: add slave bindings

From: Pierre-Louis Bossart
Date: Fri Aug 23 2019 - 11:41:37 EST




On 8/22/19 6:37 PM, Srinivas Kandagatla wrote:
This patch adds bindings for Soundwire Slave devices that includes how
SoundWire enumeration address and Link ID are used to represented in
SoundWire slave device tree nodes.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
---
.../soundwire/soundwire-controller.yaml | 75 +++++++++++++++++++
1 file changed, 75 insertions(+)
create mode 100644 Documentation/devicetree/bindings/soundwire/soundwire-controller.yaml

diff --git a/Documentation/devicetree/bindings/soundwire/soundwire-controller.yaml b/Documentation/devicetree/bindings/soundwire/soundwire-controller.yaml
new file mode 100644
index 000000000000..91aa6c6d6266
--- /dev/null
+++ b/Documentation/devicetree/bindings/soundwire/soundwire-controller.yaml
@@ -0,0 +1,75 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/soundwire/soundwire-controller.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: SoundWire Controller Generic Binding
+
+maintainers:
+ - Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
+
+description: |
+ SoundWire busses can be described with a node for the SoundWire controller
+ device and a set of child nodes for each SoundWire slave on the bus.
+
+properties:
+ $nodename:
+ pattern: "^soundwire(@.*|-[0-9a-f])*$"
+
+ "#address-cells":
+ const: 2
+
+ "#size-cells":
+ const: 0
+
+patternProperties:
+ "^.*@[0-9a-f]+$":
+ type: object
+
+ properties:
+ compatible:
+ pattern: "^sdw[0-9][0-9a-f]{4}[0-9a-f]{4}[0-9a-f]{2}$"

So is this a 64-bit value, as in the MIPI spec, or is this part of the _ADR description?
I also don't get why the first item in in base10?


+ description:
+ Is the textual representation of SoundWire Enumeration
+ address. compatible string should contain SoundWire Version ID,
+ Manufacturer ID, Part ID and Class ID in order and shall be in
+ lower-case hexadecimal with leading zeroes.
+ Valid sizes of these fields are
+ Version ID is 1 nibble, number '0x1' represents SoundWire 1.0
+ and '0x2' represents SoundWire 1.1 and so on.
+ MFD is 4 nibbles
+ PID is 4 nibbles
+ CID is 2 nibbles
+ More Information on detail of encoding of these fields can be
+ found in MIPI Alliance DisCo & SoundWire 1.0 Specifications.
+
+ reg:
+ maxItems: 1
+ description:
+ Instance ID and Link ID of SoundWire Device Address.
+
+ required:
+ - compatible
+ - reg
+
+examples:
+ - |
+ soundwire@c2d0000 {
+ #address-cells = <2>;
+ #size-cells = <0>;
+ compatible = "qcom,soundwire-v1.5.0";
+ reg = <0x0c2d0000 0x2000>;
+
+ speaker@1 {
+ compatible = "sdw10217201000";
+ reg = <1 0>;
+ };
+
+ speaker@2 {
+ compatible = "sdw10217201000";
+ reg = <2 0>;
+ };
+ };
+
+...