linux-kernel - Re: [PATCH v2 lora-next 1/4] dt-bindings: lora: sx130x: add basic documentation

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Date:   Tue, 22 Jan 2019 20:36:16 +0000
From:   Ben Whitten <ben.whitten@...il.com>
To:     Rob Herring <robh@...nel.org>
Cc:     Andreas Färber <afaerber@...e.de>,
        netdev <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        devicetree@...r.kernel.org, Mark Rutland <mark.rutland@....com>,
        linux-lpwan@...ts.infradead.org,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH v2 lora-next 1/4] dt-bindings: lora: sx130x: add basic
 documentation

Hi,

On 22/01/2019 20:04, Rob Herring wrote:
> On Tue, Jan 22, 2019 at 12:07 PM Ben Whitten <ben.whitten@...il.com> wrote:
>>
>> From: Ben Whitten <ben.whitten@...il.com>
>>
>> Add basic documentation in YAML format for the SX130x series concentrators
>> from Semtech.
>> Required is; the location on the SPI bus and the compatible string.
>>
>> Signed-off-by: Ben Whitten <ben.whitten@...il.com>
>> ---
>> v1 -> v2:
>> * Dropped reset-gpios, radio-spi from required.
>> * Dropped spi-max-frequency from binding.
>> * Changed compatible to allow fallback from SX1308 to SX1301.
>> * Wording changes in commit and descriptions.
>> * Dual licence
>> * Incorperate Robs comments on child node and spi wrapper
>> ---
>>   .../bindings/net/lora/semtech,sx130x.yaml     | 96 +++++++++++++++++++
>>   1 file changed, 96 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/net/lora/semtech,sx130x.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/net/lora/semtech,sx130x.yaml b/Documentation/devicetree/bindings/net/lora/semtech,sx130x.yaml
>> new file mode 100644
>> index 000000000000..41919fb67ec4
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/net/lora/semtech,sx130x.yaml
>> @@ -0,0 +1,96 @@
>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/net/lora/semtech,sx130x.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Semtech LoRa concentrator
>> +
>> +maintainers:
>> +  - Andreas Färber <afaerber@...e.de>
>> +  - Ben Whitten <ben.whitten@...il.com>
>> +
>> +description: |
>> +  Semtech LoRa concentrator SX130x digital baseband chip is capable of
>> +  demodulating LoRa signals on 8 channels simultaneously.
>> +
>> +  It is typically paired with two SX125x IQ radios controlled over an
>> +  SPI directly from the concentrator.
>> +
>> +  The concentrator itself is controlled over SPI.
>> +
>> +properties:
>> +  compatible:
>> +    items:
>> +      - enum:
>> +        - semtech,sx1308
>> +      - enum:
>> +        - semtech,sx1301
> 
> I think you want:
> 
> oneOf:
>    - items:
>        - enum:
>            - semtech,sx1308
>        - const: semtech,sx1301
>    - items:
>        - const: semtech,sx1301
> 
> That covers these 2 cases:
> "semtech,sx1308", "semtech,sx1301"
> "semtech,sx1301"
> 

Ah yes, that is what I was after. Thanks!

>> +
>> +  reg:
>> +    maxItems: 1
>> +    description: The chip select on the SPI bus.
>> +
>> +  reset-gpios:
>> +    maxItems: 1
>> +    description: A connection of the reset gpio line.
>> +
>> +  radio-spi:
>> +    type: object
>> +    description: The concentrator can have two radios connected which are
>> +      contained within the following node.
>> +
>> +    properties:
>> +      '#address-cells':
>> +        const: 1
>> +
>> +      '#size-cells':
>> +        const: 0
>> +
>> +    patternProperties:
>> +      "^[a-zA-Z0-9]@[0-1]$":
> 
> Is any node name allowed? We like to have generic names. 'lora' is
> fine for me, but I'm don't know if other devices could be attached?
> 

This sub bus will only have IQ radios attached to it, perhaps 'radio@0'
as the system can handle other modulations.

> I thought up to 8 concentrators was supported? Or channels and radios
> aren't 1-1?

You can have multiple concentrator chips (SX130x) however each one may 
have up to two IQ radios (SX125x) attached to its bus.
And in terms of channels the system can listen on, the concentrator has 
9 LoRa demodulators and 1 (G)FSK demodulator.

> 
> This too should have 'type: object' since it is a node name.
> 

Ah yes

>> +        properties:
>> +          reg:
>> +            maxItems: 1
> 
> You can add:
> minimum: 0
> maximum: 1 (or 7?)
> 
>> +        required:
>> +          - reg
>> +
>> +    required:
>> +      - '#address-cells'
>> +      - '#size-cells'
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +
>> +examples:
>> +  - |
>> +
>> +    #include <dt-bindings/gpio/gpio.h>
>> +
>> +    spi {
>> +      #address-cells = <1>;
>> +      #size-cells = <0>;
>> +
>> +      concentrator0: lora@0 {
>> +        compatible = "semtech,sx1301";
>> +        reg = <0>;
>> +        reset-gpios = <&pioB 27 GPIO_ACTIVE_HIGH>;
>> +        spi-max-frequency = <8000000>;
>> +
>> +        radio-spi {
>> +          #address-cells = <1>;
>> +          #size-cells = <0>;
>> +
>> +          radio0: lora@0 {
>> +            compatible = "semtech,sx1257";
>> +            reg = <0>;
>> +          };
>> +
>> +          radio1: lora@1 {
>> +            compatible = "semtech,sx1257";
>> +            reg = <1>;
>> +          };
>> +        };
>> +      };
>> +    };
>> --
>> 2.17.1
>>

Thanks!
Ben Whitten