Re: [PATCH 1/3] iio: accel: bmc150-accel: Add DT bindings

[Jonathan Cameron <jic23@kernel.org>]

On Sun,  1 Nov 2020 13:28:31 +0100
Linus Walleij <linus.walleij@linaro.org> wrote:

> These accelerometers have bindings used in the kernel and
> several device trees but no proper bindings documentation.
> Add it.
> 
> Also add a compatible for the BMA222 that I am right now
> adding support for in the driver.
> 
> Cc: devicetree@vger.kernel.org
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Hi Linus,

A few minor things inline.

Great to be plugging some of the holes in binding docs.
Doing a complete check is on my todo list :)

Jonathan

> ---
>  .../bindings/iio/accel/bosch,bmc-bmi-bma.yaml | 72 +++++++++++++++++++

So far we only have a few bindings that aren't named after a supported part.
Give we have other devices that match these letters, I don't think we want to
do it here.  Just confused people!

Pick a part and name it after that.

>  1 file changed, 72 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/accel/bosch,bmc-bmi-bma.yaml
> 
> diff --git a/Documentation/devicetree/bindings/iio/accel/bosch,bmc-bmi-bma.yaml b/Documentation/devicetree/bindings/iio/accel/bosch,bmc-bmi-bma.yaml
> new file mode 100644
> index 000000000000..11b8b68aaf3e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/accel/bosch,bmc-bmi-bma.yaml
> @@ -0,0 +1,72 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/accel/bosch,bmc-bmi-bma.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Bosch BMCxxx, BMIxxx and BMAxxx Accelerometers

Some of them...  see bma180.txt in the same directory.
I'd go with bma255 and similar (chose your favourite part number)
> +
> +maintainers:
> +  - Linus Walleij <linus.walleij@linaro.org>
> +
> +description:
> +  3 axis accelerometers with varying range and I2C or SPI
> +  3-wire interface.

Looks like 4-wire to me.  CSB, SPI-CLK, SDO, SDI.

> +
> +properties:
> +  compatible:
> +    enum:
> +      - bosch,bmc150
> +      - bosch,bmi055
> +      - bosch,bma255
> +      - bosch,bma250e
> +      - bosch,bma222
> +      - bosch,bma222e
> +      - bosch,bma280
> +
> +  reg:
> +    maxItems: 1
> +
> +  vdd-supply: true
> +  vddio-supply: true
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  mount-matrix:
> +    description: an optional 3x3 mounting rotation matrix.
> +
> +  spi-max-frequency: true

Don't suppose these all share a common max?
I looked at a few and 10MHz was the value for those.
Always nice to pin things down a bit if we can!

> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    i2c {
> +        #include <dt-bindings/interrupt-controller/irq.h>
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +        accelerometer@8 {
> +            compatible = "bosch,bma222";
> +            reg = <0x08>;
> +            vddio-supply = <&vddio>;
> +            vdd-supply = <&vdd>;
> +            interrupts = <57 IRQ_TYPE_EDGE_FALLING>;
> +        };
> +    };
> +  - |
> +    # include <dt-bindings/interrupt-controller/irq.h>
> +    spi {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +        accel@0 {
> +            compatible = "bosch,bma222";
> +            reg = <0>;
> +            spi-max-frequency = <10000000>;
> +        };
> +    };
> +...