[PATCH v5 2/6] dt-bindings: auxdisplay: Add Titan Micro Electronics TM1628
Krzysztof Kozlowski
krzk at kernel.org
Mon Mar 21 01:34:32 PDT 2022
On 18/03/2022 21:50, Robin Murphy wrote:
> On 2022-02-25 21:13, Heiner Kallweit wrote:
>> Add a YAML schema binding for TM1628 auxdisplay
>> (7/11-segment LED) controller.
>>
>> This patch is partially based on previous work from
>> Andreas Färber <afaerber at suse.de>.
>>
>> Co-developed-by: Andreas Färber <afaerber at suse.de>
>> Signed-off-by: Andreas Färber <afaerber at suse.de>
>> Signed-off-by: Heiner Kallweit <hkallweit1 at gmail.com>
>> ---
>> v5:
>> - add vendor prefix to driver-specific properties
>> ---
>> .../bindings/auxdisplay/titanmec,tm1628.yaml | 92 +++++++++++++++++++
>> 1 file changed, 92 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/auxdisplay/titanmec,tm1628.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/auxdisplay/titanmec,tm1628.yaml b/Documentation/devicetree/bindings/auxdisplay/titanmec,tm1628.yaml
>> new file mode 100644
>> index 000000000..2a1ef692c
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/auxdisplay/titanmec,tm1628.yaml
>> @@ -0,0 +1,92 @@
>> +# SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/auxdisplay/titanmec,tm1628.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Titan Micro Electronics TM1628 LED controller
>> +
>> +maintainers:
>> + - Andreas Färber <afaerber at suse.de>
>> + - Heiner Kallweit <hkallweit1 at gmail.com>
>> +
>> +allOf:
>> + - $ref: /schemas/spi/spi-peripheral-props.yaml#
>> +
>> +properties:
>> + compatible:
>> + const: titanmec,tm1628
>> +
>> + reg:
>> + maxItems: 1
>> +
>> + titanmec,grid:
>> + description:
>> + Mapping of display digit position to grid number.
>> + This implicitly defines the display size.
>> + $ref: /schemas/types.yaml#/definitions/uint8-array
>> + minItems: 1
>> + maxItems: 7
>> +
>> + titanmec,segment-mapping:
>> + description:
>> + Mapping of 7 segment display segments A-G to bit numbers 1-12.
>> + $ref: /schemas/types.yaml#/definitions/uint8-array
>> + minItems: 7
>> + maxItems: 7
>> +
>> + "#address-cells":
>> + const: 2
>> +
>> + "#size-cells":
>> + const: 0
>> +
>> +required:
>> + - compatible
>> + - reg
>
> Would it be fair to say that "spi-lsb-first" and "spi-3wire" are also
> required? The chips aren't configurable so won't exactly be usable any
> other way. Furthermore I believe the transmission format actually works
> out equivalent to SPI mode 3, so should warrant "spi-cpha" and
> "spi-cpol" as well.
>
>> +
>> +patternProperties:
>> + "^.*@[1-7],([1-9]|1[0-6])$":
>> + type: object
>> + $ref: /schemas/leds/common.yaml#
>> + unevaluatedProperties: false
>> + description: |
>> + Properties for a single LED.
>> +
>> + properties:
>> + reg:
>> + description: |
>> + 1-based grid number, followed by 1-based segment bit number.
>> + maxItems: 1
>> +
>> + required:
>> + - reg
>
> I'm concerned that this leaves us no room to support the additional
> keypad functionality in future. Having now double-checked a datasheet,
> the inputs are also a two-dimensional mux (sharing the segment lines),
> so the device effectively has two distinct but numerically-overlapping
> child address spaces - one addressed by (grid,segment) and the other by
> (segment,key).
>
> Rob, Krysztof, any thoughts on the best DT idiom to leave accommodation
> for that? I'm thinking either require an intermediate node to contain
> each notional address space, or perhaps add another leading address cell
> to select between them? I don't believe any of these things have further
> functionality beyond that.
I think intermediate nodes - leds, keys - are more appropriate, because
it is self-describing. Additional address space number would require
decoding this "0" or "1" into LED/key. For complex devices - like PMICs
with regulators, RTC and clocks - we already have such patterns.
Best regards,
Best regards,
Krzysztof
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