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Message-ID: <20230924175720.3be2540b@jic23-huawei>
Date: Sun, 24 Sep 2023 17:57:20 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: David Lechner <dlechner@...libre.com>
Cc: linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>,
Michael Hennerich <Michael.Hennerich@...log.com>,
Nuno Sá <nuno.sa@...log.com>,
Axel Haslam <ahaslam@...libre.com>,
Philip Molloy <pmolloy@...libre.com>,
Apelete Seketeli <aseketeli@...libre.com>
Subject: Re: [PATCH v2 01/19] dt-bindings: iio: resolver: add devicetree
bindings for ad2s1210
On Thu, 21 Sep 2023 09:43:42 -0500
David Lechner <dlechner@...libre.com> wrote:
> This adds new DeviceTree bindings for the Analog Devices, Inc. AD2S1210
> resolver-to-digital converter.
>
> Co-developed-by: Apelete Seketeli <aseketeli@...libre.com>
> Signed-off-by: Apelete Seketeli <aseketeli@...libre.com>
> Signed-off-by: David Lechner <dlechner@...libre.com>
We've become more fussy about it recently but for new bindings at least,
we want to include all power supplies and mark them as required.
A few other trivial things inline,
Jonathan
> ---
>
> v2 changes:
> * Add Co-developed-by:
> * Remove extraneous quotes on strings
> * Remove extraneous pipe on some multi-line descriptions
>
> .../bindings/iio/resolver/adi,ad2s1210.yaml | 150 ++++++++++++++++++
> 1 file changed, 150 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/iio/resolver/adi,ad2s1210.yaml
>
> diff --git a/Documentation/devicetree/bindings/iio/resolver/adi,ad2s1210.yaml b/Documentation/devicetree/bindings/iio/resolver/adi,ad2s1210.yaml
> new file mode 100644
> index 000000000000..f55c9652cfb7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/resolver/adi,ad2s1210.yaml
> @@ -0,0 +1,150 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/resolver/adi,ad2s1210.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Analog Devices AD2S1210 Resolver-to-Digital Converter
> +
> +maintainers:
> + - Michael Hennerich <michael.hennerich@...log.com>
> +
> +description: |
> + The AD2S1210 is a complete 10-bit to 16-bit resolution tracking
> + resolver-to-digital converter, integrating an on-board programmable
> + sinusoidal oscillator that provides sine wave excitation for
> + resolvers.
> +
> + The AD2S1210 allows the user to read the angular position or the
> + angular velocity data directly from the parallel outputs or through
> + the serial interface.
> +
> + A1 A0 Result
Should say what A0 and A1 are. It's down below but seems odd
that it is here for RES0 and RES1 but not the A1 and A0 signals.
> + 0 0 Normal mode - position output
> + 0 1 Normal mode - velocity output
> + 1 0 Reserved
> + 1 1 Configuration mode
> +
> + In normal mode, the resolution of the digital output is selected using
> + the RES0 and RES1 input pins. In configuration mode, the resolution is
> + selected by setting the RES0 and RES1 bits in the control register.
> +
> + RES1 RES0 Resolution (Bits)
> + 0 0 10
> + 0 1 12
> + 1 0 14
> + 1 1 16
> +
> + Note on SPI connections: The CS line on the AD2S1210 should hard-wired to
> + logic low and the WR/FSYNC line on the AD2S1210 should be connected to the
> + SPI CSn output of the SPI controller.
That is impressively random ;) Good to call it out.
> +
> + Datasheet:
> + https://www.analog.com/media/en/technical-documentation/data-sheets/ad2s1210.pdf
> +
> +properties:
> + compatible:
> + const: adi,ad2s1210
> +
> + reg:
> + maxItems: 1
> +
> + spi-max-frequency:
> + maximum: 25000000
> +
> + spi-cpha: true
> +
> + clocks:
> + maxItems: 1
> + description: External oscillator clock (CLKIN).
> +
> + reset-gpios:
> + description:
> + GPIO connected to the /RESET pin. As the line needs to be low for the
> + reset to be active, it should be configured as GPIO_ACTIVE_LOW.
> + maxItems: 1
> +
> + sample-gpios:
> + description:
> + GPIO connected to the /SAMPLE pin. As the line needs to be low to trigger
> + a sample, it should be configured as GPIO_ACTIVE_LOW.
> + maxItems: 1
> +
> + mode-gpios:
> + description:
> + GPIO lines connected to the A0 and A1 pins. These pins select the data
> + transfer mode.
> + minItems: 2
> + maxItems: 2
> +
> + resolution-gpios:
> + description:
> + GPIO lines connected to the RES0 and RES1 pins. These pins select the
> + resolution of the digital output. If omitted, it is assumed that the
> + RES0 and RES1 pins are hard-wired to match the assigned-resolution-bits
> + property.
> + minItems: 2
> + maxItems: 2
> +
> + fault-gpios:
> + description:
> + GPIO lines connected to the LOT and DOS pins. These pins combined indicate
> + the type of fault present, if any. As these pins a pulled low to indicate
> + a fault condition, they should be configured as GPIO_ACTIVE_LOW.
What if someone is being odd and connected only 1 of them?
It's annoying how often people run out of pins and do things like this.
> + minItems: 2
> + maxItems: 2
> +
> + adi,fixed-mode:
> + description:
> + This is used to indicate the selected mode if A0 and A1 are hard-wired
> + instead of connected to GPIOS (i.e. mode-gpios is omitted).
> + $ref: /schemas/types.yaml#/definitions/string
> + enum: [config, velocity, position]
> +
> + assigned-resolution-bits:
> + description:
> + Resolution of the digital output required by the application. This
> + determines the precision of the angle and/or the maximum speed that can
> + be measured. If resolution-gpios is omitted, it is assumed that RES0 and
> + RES1 are hard-wired to match this value.
> + enum: [10, 12, 14, 16]
Good description as this was non obvious.
> +
> +required:
> + - compatible
> + - reg
> + - spi-cpha
> + - clocks
> + - sample-gpios
> + - assigned-resolution-bits
> +
> +oneOf:
> + - required:
> + - mode-gpios
> + - required:
> + - adi,fixed-mode
I think this allows for both. It's fiddlier to exclude that but would be a nice
to have perhaps rather than relying on text above that says 'don't do it'.
> +
> +allOf:
> + - $ref: /schemas/spi/spi-peripheral-props.yaml#
> +
> +unevaluatedProperties: false
> +
> +examples:
> + - |
> + #include <dt-bindings/gpio/gpio.h>
> +
> + spi {
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + resolver@0 {
> + compatible = "adi,ad2s1210";
> + reg = <0>;
> + spi-max-frequency = <20000000>;
> + spi-cpha;
> + clocks = <&ext_osc>;
> + sample-gpios = <&gpio0 90 GPIO_ACTIVE_LOW>;
> + mode-gpios = <&gpio0 86 0>, <&gpio0 87 0>;
> + resolution-gpios = <&gpio0 88 0>, <&gpio0 89 0>;
> + assigned-resolution-bits = <16>;
> + };
> + };
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