[1/2] dt-bindings: input: add Semtech SX951x binding

Add device-tree binding for the Semtech SX9512/SX9513 family of touch
controllers with integrated LED driver.

Signed-off-by: David Bauer <mail@david-bauer.net>
---
 .../bindings/input/semtech,sx951x.yaml        | 180 ++++++++++++++++++
 1 file changed, 180 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/semtech,sx951x.yaml

Hi David,

On Mon, May 05, 2025 at 10:38:45PM +0200, David Bauer wrote:
> The Semtech SX9512/SX9513 is a family of capacitive touch-keyboard
> controllers.
> 
> All chips offer 8 channel touch sensitive inputs with one LED driver per
> output channel.
> 
> The also SX9512 supports proximity detection which is currently not
> supported with the driver.
> 
> This chip can be found on the Genexis Pulse EX400 repeater platform.
> 
> Link: https://www.mouser.com/datasheet/2/761/SEMTS05226_1-2575172.pdf
> 
> Signed-off-by: David Bauer <mail@david-bauer.net>
> ---
>  drivers/input/keyboard/Kconfig  |  11 +
>  drivers/input/keyboard/Makefile |   1 +
>  drivers/input/keyboard/sx951x.c | 490 ++++++++++++++++++++++++++++++++
>  3 files changed, 502 insertions(+)
>  create mode 100644 drivers/input/keyboard/sx951x.c
> 
> diff --git a/drivers/input/keyboard/Kconfig b/drivers/input/keyboard/Kconfig
> index 1d0c5f4c0f99..6dc397389c64 100644
> --- a/drivers/input/keyboard/Kconfig
> +++ b/drivers/input/keyboard/Kconfig
> @@ -616,6 +616,17 @@ config KEYBOARD_SUNKBD
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called sunkbd.
>  
> +config KEYBOARD_SX951X
> +	tristate "Semtech SX951X capacitive touch controller"
> +	depends on OF && I2C

I do not believe it should depend on OF. Please have the driver use
generic device properties instead (device_property_*()).

...

> +
> + #include <linux/kernel.h>
> + #include <linux/module.h>
> + #include <linux/input.h>
> + #include <linux/leds.h>
> + #include <linux/of.h>

You will likely need mod_devicetable.h instead of of.h.

> + #include <linux/regmap.h>
> + #include <linux/i2c.h>
> + #include <linux/gpio/consumer.h>
> + #include <linux/bitfield.h>
> +
> + /* Generic properties */
> +#define SX951X_I2C_ADDRESS		0x2b
> +#define SX951XB_I2C_ADDRESS_		0x2d

Why underscore at the end?

...

> +
> +#ifdef CONFIG_LEDS_CLASS
> +		error = sx951x_led_init(priv, child, reg);
> +		if (error) {
> +			dev_err(dev, "Failed to initialize LED %d: %d\n",
> +				reg, error);
> +			return error;
> +		}
> +#endif

Please provide stub for sx951x_led_init() instead of using #ifdef here. 

...
> +
> +	priv = devm_kzalloc(dev,
> +			    sizeof(struct sx951x_priv),

sizeof(*priv)

Thanks.

On 05/05/2025 22:38, David Bauer wrote:
> Add device-tree binding for the Semtech SX9512/SX9513 family of touch
> controllers with integrated LED driver.
> 
> Signed-off-by: David Bauer <mail@david-bauer.net>

You CC-ed an address, which suggests you do not work on mainline kernel
or you do not use get_maintainers.pl/b4/patman. Please rebase and always
work on mainline or start using mentioned tools, so correct addresses
will be used.

Please use scripts/get_maintainers.pl to get a list of necessary people
and lists to CC (and consider --no-git-fallback argument, so you will
not CC people just because they made one commit years ago). It might
happen, that command when run on an older kernel, gives you outdated
entries. Therefore please be sure you base your patches on recent Linux
kernel.

Tools like b4 or scripts/get_maintainer.pl provide you proper list of
people, so fix your workflow. Tools might also fail if you work on some
ancient tree (don't, instead use mainline) or work on fork of kernel
(don't, instead use mainline). Just use b4 and everything should be
fine, although remember about `b4 prep --auto-to-cc` if you added new
patches to the patchset.


> ---
>  .../bindings/input/semtech,sx951x.yaml        | 180 ++++++++++++++++++
>  1 file changed, 180 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/input/semtech,sx951x.yaml
> 
> diff --git a/Documentation/devicetree/bindings/input/semtech,sx951x.yaml b/Documentation/devicetree/bindings/input/semtech,sx951x.yaml
> new file mode 100644
> index 000000000000..e4f938decd86
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/semtech,sx951x.yaml
> @@ -0,0 +1,180 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/input/semtech,sx951x.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Semtech SX9512/SX9513 based capacitive touch sensors
> +
> +description: |

Do not need '|' unless you need to preserve formatting.

> +  The Semtech SX9512/SX9513 Family of capacitive touch controllers
> +  with integrated LED drivers. The device communication is using I2C only.
> +
> +maintainers:
> +  - David Bauer <mail@david-bauer.net>
> +
> +properties:
> +  compatible:
> +    enum:
> +      - semtech,sx9512
> +      - semtech,sx9513

Devices are not compatible? What are the differences?

> +
> +  reg:
> +    maxItems: 1
> +
> +  '#address-cells':
> +    const: 1
> +
> +  '#size-cells':
> +    const: 0
> +
> +  poll-interval:
> +    default: 100
> +    description: |

Do not need '|' unless you need to preserve formatting. Same comment
everywhere.

> +      The polling interval for touch events in milliseconds.

Missing -ms property unit suffix... unless you are using existing
property from common schema, but I do not see any reference (and thus
unevaluatedProperties at the end).

> +
> +patternProperties:
> +  "^channel@[0-7]$":
> +    $ref: input.yaml#
> +    type: object
> +    description: |
> +      Each node represents a channel of the touch controller.
> +      Each channel provides a capacitive touch sensor input and
> +      an LED driver output.
> +
> +    properties:
> +      reg:
> +        enum: [0, 1, 2, 3, 4, 5, 6, 7]
> +
> +      linux,keycodes:
> +        maxItems: 1
> +        description: |
> +          Specifies an array of numeric keycode values to
> +          be used for the channels. If this property is
> +          omitted, the channel is not used as a key.
> +
> +      semtech,cin-delta:

Use proper unit suffix and express it in pF.

> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        minimum: 0
> +        maximum: 3
> +        default: 3
> +        description: |
> +          The capacitance delta which is used to detect a touch
> +          or release event. The property value is mapped to a
> +          farad range between 7pF and 2.3pF internally. The delta
> +          becomes smaller the higher the value is.
> +
> +      semtech,sense-threshold:
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        minimum: 0
> +        maximum: 255
> +        default: 4
> +        description: |
> +          The threshold value after which the channel detects a touch.
> +          Refer to the datasheet for the internal calculation of the
> +          resulting touch sensitivity.
> +
> +      led:

I think subnode is here not needed. This should be part of the channel,
probably.

> +        $ref: /schemas/leds/common.yaml#
> +        type: object
> +        unevaluatedProperties: false
> +        description: |
> +          Presence of this property indicates the channel
> +          is used as an LED driver.
> +
> +    required:
> +      - reg
> +
> +    additionalProperties: false

unevaluatedProperties instead

> +
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/input/input.h>
> +    #include <dt-bindings/leds/common.h>
> +    i2c {
> +      #address-cells = <1>;
> +      #size-cells = <0>;
> +
> +      touch@2b {
> +        compatible = "semtech,sx9512";
> +

Drop blank line

> +        reg = <0x2b>;
> +


Best regards,
Krzysztof

On Tue, May 06, 2025 at 12:05:43PM +0200, David Bauer wrote:
> Hi Krzysztof,
> 
> thanks for the review.
> 
> On 5/6/25 08:21, Krzysztof Kozlowski wrote:
> > On 05/05/2025 22:38, David Bauer wrote:
> > > Add device-tree binding for the Semtech SX9512/SX9513 family of touch
> > > controllers with integrated LED driver.
> > > 
> > > Signed-off-by: David Bauer <mail@david-bauer.net>
> > 
> > You CC-ed an address, which suggests you do not work on mainline kernel
> > or you do not use get_maintainers.pl/b4/patman. Please rebase and always
> > work on mainline or start using mentioned tools, so correct addresses
> > will be used.
> I'm a bit unsure what you are referring to - maybe I've set the options
> for get_maintainer.pl wrong, but i use
> 
> get_maintainer.pl --nogit --nogit-fallback --norolestats --nol
> 
> to determine TO recipients and
> 
> get_maintainer.pl --nogit --nogit-fallback --norolestats --nom
> 
> for CC destinations.
> 
> Granted, my tree was a bit out of date but it was from mainline
> and after rebase both commands returned consistent results.
> 
> Hope you can provide me with some guidance there.

Probably that I don't use 'robh+dt' for a while now. Just 'robh'.

> > 
> > Please use scripts/get_maintainers.pl to get a list of necessary people
> > and lists to CC (and consider --no-git-fallback argument, so you will
> > not CC people just because they made one commit years ago). It might
> > happen, that command when run on an older kernel, gives you outdated
> > entries. Therefore please be sure you base your patches on recent Linux
> > kernel.
> > 
> > Tools like b4 or scripts/get_maintainer.pl provide you proper list of
> > people, so fix your workflow. Tools might also fail if you work on some
> > ancient tree (don't, instead use mainline) or work on fork of kernel
> > (don't, instead use mainline). Just use b4 and everything should be
> > fine, although remember about `b4 prep --auto-to-cc` if you added new
> > patches to the patchset.
> > 
> > 
> > > ---
> > >   .../bindings/input/semtech,sx951x.yaml        | 180 ++++++++++++++++++
> > >   1 file changed, 180 insertions(+)
> > >   create mode 100644 Documentation/devicetree/bindings/input/semtech,sx951x.yaml
> > > 
> > > diff --git a/Documentation/devicetree/bindings/input/semtech,sx951x.yaml b/Documentation/devicetree/bindings/input/semtech,sx951x.yaml
> > > new file mode 100644
> > > index 000000000000..e4f938decd86
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/input/semtech,sx951x.yaml
> > > @@ -0,0 +1,180 @@
> > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/input/semtech,sx951x.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Semtech SX9512/SX9513 based capacitive touch sensors
> > > +
> > > +description: |
> > 
> > Do not need '|' unless you need to preserve formatting.
> > 
> > > +  The Semtech SX9512/SX9513 Family of capacitive touch controllers
> > > +  with integrated LED drivers. The device communication is using I2C only.
> > > +
> > > +maintainers:
> > > +  - David Bauer <mail@david-bauer.net>
> > > +
> > > +properties:
> > > +  compatible:
> > > +    enum:
> > > +      - semtech,sx9512
> > > +      - semtech,sx9513
> > 
> > Devices are not compatible? What are the differences?
> 
> The SX9513 is a cost-reduced version which does not
> support proximity sensing. With the current support
> of the driver they work identical. Should i add this
> information as a comment?

In the 'description' above, but not the driver support part.

> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  '#address-cells':
> > > +    const: 1
> > > +
> > > +  '#size-cells':
> > > +    const: 0
> > > +
> > > +  poll-interval:
> > > +    default: 100
> > > +    description: |
> > 
> > Do not need '|' unless you need to preserve formatting. Same comment
> > everywhere.
> > 
> > > +      The polling interval for touch events in milliseconds.
> > 
> > Missing -ms property unit suffix... unless you are using existing
> > property from common schema, but I do not see any reference (and thus
> > unevaluatedProperties at the end).
> > 
> > > +
> > > +patternProperties:
> > > +  "^channel@[0-7]$":
> > > +    $ref: input.yaml#
> > > +    type: object
> > > +    description: |
> > > +      Each node represents a channel of the touch controller.
> > > +      Each channel provides a capacitive touch sensor input and
> > > +      an LED driver output.
> > > +
> > > +    properties:
> > > +      reg:
> > > +        enum: [0, 1, 2, 3, 4, 5, 6, 7]

maximum: 7

> > > +
> > > +      linux,keycodes:
> > > +        maxItems: 1
> > > +        description: |
> > > +          Specifies an array of numeric keycode values to
> > > +          be used for the channels. If this property is
> > > +          omitted, the channel is not used as a key.
> > > +
> > > +      semtech,cin-delta:
> > 
> > Use proper unit suffix and express it in pF.
> 
> To represent 2.3 and 3.8 pF, would it be better to represent in
> femtofarad?

Yes.


> > > +        $ref: /schemas/types.yaml#/definitions/uint32
> > > +        minimum: 0
> > > +        maximum: 3
> > > +        default: 3
> > > +        description: |
> > > +          The capacitance delta which is used to detect a touch
> > > +          or release event. The property value is mapped to a
> > > +          farad range between 7pF and 2.3pF internally. The delta
> > > +          becomes smaller the higher the value is.
> > > +
> > > +      semtech,sense-threshold:
> > > +        $ref: /schemas/types.yaml#/definitions/uint32
> > > +        minimum: 0
> > > +        maximum: 255
> > > +        default: 4
> > > +        description: |
> > > +          The threshold value after which the channel detects a touch.
> > > +          Refer to the datasheet for the internal calculation of the
> > > +          resulting touch sensitivity.
> > > +
> > > +      led:
> > 
> > I think subnode is here not needed. This should be part of the channel,
> > probably.
> 
> Just to be sure - you mean to have a property "led" upon which instructs
> the channel to be used to drive an LED and include the LED specific
> properties in the node of the channel?

Actually, I think it is fine as-is if the LED driver works 
simultaneously with the touch input and isn't mutually exclusive. The 
'led' node is for the LED. The parent node is the driver/controller.

If they are mutually exclusive, then I'd say you want channel@[0-7] and 
led@[0-7] nodes at the same level.

Rob