diff mbox series

[03/40] dt-bindings: touchscreen: ti,am3359-tsc: New yaml description

Message ID 20210825152518.379386-4-miquel.raynal@bootlin.com (mailing list archive)
State New, archived
Headers show
Series TI AM437X ADC1 | expand

Commit Message

Miquel Raynal Aug. 25, 2021, 3:24 p.m. UTC
This touchscreen controller is already described in a text file:
Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt

After introducing a proper description of the MFD, this is the second
step. The file cannot be removed yet as it also contains an ADC
description.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 .../input/touchscreen/ti,am3359-tsc.yaml      | 89 +++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml

Comments

Jonathan Cameron Aug. 30, 2021, 1:36 p.m. UTC | #1
On Wed, 25 Aug 2021 17:24:41 +0200
Miquel Raynal <miquel.raynal@bootlin.com> wrote:

> This touchscreen controller is already described in a text file:
> Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt
> 
> After introducing a proper description of the MFD, this is the second
> step. The file cannot be removed yet as it also contains an ADC
> description.
> 
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
>  .../input/touchscreen/ti,am3359-tsc.yaml      | 89 +++++++++++++++++++
>  1 file changed, 89 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml
> 
> diff --git a/Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml b/Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml
> new file mode 100644
> index 000000000000..2d4ce6d04f53
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml
> @@ -0,0 +1,89 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/input/touchscreen/ti,am3359-tsc.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: TI AM3359 Touchscreen controller
> +
> +maintainers:
> +  - Miquel Raynal <miquel.raynal@bootlin.com>
> +
> +properties:
> +  compatible:
> +    const: ti,am3359-tsc
> +
> +  ti,wires:
> +    description: Wires refer to application modes i.e. 4/5/8 wire touchscreen
> +      support on the platform.
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    enum: [4, 5, 8]
> +
> +  ti,x-plate-resistance:
> +    description: X plate resistance
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +
> +  ti,coordinate-readouts:
> +    description: The sequencer supports a total of 16 programmable steps. Each
> +      step is used to read a single coordinate. A single readout is enough but
> +      multiple reads can increase the quality. A value of 5 means, 5 reads for
> +      X, 5 for Y and 2 for Z (always). This utilises 12 of the 16 software steps
> +      available. The remaining 4 can be used by the ADC.
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 1
> +    maximum: 6
> +
> +  ti,wire-config:
> +    description: Different boards could have a different order for connecting
> +      wires on touchscreen. We need to provide an 8-bit number where the
> +      first four bits represent the analog lines and the next 4 bits represent
> +      positive/negative terminal on that input line. Notations to represent the
> +      input lines and terminals respectively are as follows, AIN0 = 0, AIN1 = 1
> +      and so on untill AIN7 = 7. XP = 0, XN = 1, YP = 2, YN = 3.
> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +    minItems: 4
> +    maxItems: 8
> +
> +  ti,charge-delay:
> +    description: Length of touch screen charge delay step in terms of ADC clock
> +      cycles. Charge delay value should be large in order to avoid false pen-up
> +      events. This value effects the overall sampling speed, hence need to be
> +      kept as low as possible, while avoiding false pen-up event. Start from a
> +      lower value, say 0x400, and increase value until false pen-up events are
> +      avoided. The pen-up detection happens immediately after the charge step,
> +      so this does in fact function as a hardware knob for adjusting the amount
> +      of "settling time".
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +
> +required:
> +  - compatible
> +  - ti,wires

Are these all required?  Seems like the driver will work fine without some
of them and isn't doing appropriate error checking for their presence..

> +  - ti,x-plate-resistance
> +  - ti,coordinate-readouts
> +  - ti,wire-config
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +
> +    tscadc: tscadc@0 {
> +        compatible = "ti,am3359-tscadc";
> +        reg = <0x0 0x1000>;
> +        interrupts = <GIC_SPI 16 IRQ_TYPE_LEVEL_HIGH>;
> +        clocks = <&adc_tsc_fck>;
> +        clock-names = "fck";
> +        status = "disabled";
> +        dmas = <&edma 53 0>, <&edma 57 0>;
> +        dma-names = "fifo0", "fifo1";
> +
> +        tsc {
> +            compatible = "ti,am3359-tsc";
> +            ti,wires = <4>;
> +            ti,x-plate-resistance = <200>;
> +            ti,coordinate-readouts = <5>;
> +            ti,wire-config = <0x00 0x11 0x22 0x33>;
> +            ti,charge-delay = <0x400>;
> +        };
> +    };
Rob Herring (Arm) Aug. 31, 2021, 7:37 p.m. UTC | #2
On Wed, Aug 25, 2021 at 05:24:41PM +0200, Miquel Raynal wrote:
> This touchscreen controller is already described in a text file:
> Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt
> 
> After introducing a proper description of the MFD, this is the second
> step. The file cannot be removed yet as it also contains an ADC
> description.
> 
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
>  .../input/touchscreen/ti,am3359-tsc.yaml      | 89 +++++++++++++++++++
>  1 file changed, 89 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml
> 
> diff --git a/Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml b/Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml
> new file mode 100644
> index 000000000000..2d4ce6d04f53
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml
> @@ -0,0 +1,89 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/input/touchscreen/ti,am3359-tsc.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: TI AM3359 Touchscreen controller
> +
> +maintainers:
> +  - Miquel Raynal <miquel.raynal@bootlin.com>
> +
> +properties:
> +  compatible:
> +    const: ti,am3359-tsc
> +
> +  ti,wires:
> +    description: Wires refer to application modes i.e. 4/5/8 wire touchscreen
> +      support on the platform.
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    enum: [4, 5, 8]
> +
> +  ti,x-plate-resistance:
> +    description: X plate resistance
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +
> +  ti,coordinate-readouts:
> +    description: The sequencer supports a total of 16 programmable steps. Each
> +      step is used to read a single coordinate. A single readout is enough but
> +      multiple reads can increase the quality. A value of 5 means, 5 reads for
> +      X, 5 for Y and 2 for Z (always). This utilises 12 of the 16 software steps
> +      available. The remaining 4 can be used by the ADC.
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 1
> +    maximum: 6
> +
> +  ti,wire-config:
> +    description: Different boards could have a different order for connecting
> +      wires on touchscreen. We need to provide an 8-bit number where the
> +      first four bits represent the analog lines and the next 4 bits represent
> +      positive/negative terminal on that input line. Notations to represent the
> +      input lines and terminals respectively are as follows, AIN0 = 0, AIN1 = 1
> +      and so on untill AIN7 = 7. XP = 0, XN = 1, YP = 2, YN = 3.
> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +    minItems: 4
> +    maxItems: 8
> +
> +  ti,charge-delay:
> +    description: Length of touch screen charge delay step in terms of ADC clock
> +      cycles. Charge delay value should be large in order to avoid false pen-up
> +      events. This value effects the overall sampling speed, hence need to be
> +      kept as low as possible, while avoiding false pen-up event. Start from a
> +      lower value, say 0x400, and increase value until false pen-up events are
> +      avoided. The pen-up detection happens immediately after the charge step,
> +      so this does in fact function as a hardware knob for adjusting the amount
> +      of "settling time".
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +
> +required:
> +  - compatible
> +  - ti,wires
> +  - ti,x-plate-resistance
> +  - ti,coordinate-readouts
> +  - ti,wire-config
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>

I prefer that MFDs have just 1 complete example in the MFD schema. 

> +
> +    tscadc: tscadc@0 {

Drop unused labels.

> +        compatible = "ti,am3359-tscadc";
> +        reg = <0x0 0x1000>;
> +        interrupts = <GIC_SPI 16 IRQ_TYPE_LEVEL_HIGH>;
> +        clocks = <&adc_tsc_fck>;
> +        clock-names = "fck";
> +        status = "disabled";

status, again.

> +        dmas = <&edma 53 0>, <&edma 57 0>;
> +        dma-names = "fifo0", "fifo1";
> +
> +        tsc {
> +            compatible = "ti,am3359-tsc";
> +            ti,wires = <4>;
> +            ti,x-plate-resistance = <200>;
> +            ti,coordinate-readouts = <5>;
> +            ti,wire-config = <0x00 0x11 0x22 0x33>;
> +            ti,charge-delay = <0x400>;
> +        };
> +    };
> -- 
> 2.27.0
> 
>
Miquel Raynal Sept. 1, 2021, 7:42 a.m. UTC | #3
Hi Rob,

> > +examples:
> > +  - |
> > +    #include <dt-bindings/interrupt-controller/arm-gic.h>  
> 
> I prefer that MFDs have just 1 complete example in the MFD schema. 

Just to be on the same line, you ask me to drop the all the lines from

	tscadc:

up to

	dma-names = ...;

and keep only the tsc node, right?

I guess I should do the same in the ADC binding then.

> 
> > +
> > +    tscadc: tscadc@0 {  
> 
> Drop unused labels.
> 
> > +        compatible = "ti,am3359-tscadc";
> > +        reg = <0x0 0x1000>;
> > +        interrupts = <GIC_SPI 16 IRQ_TYPE_LEVEL_HIGH>;
> > +        clocks = <&adc_tsc_fck>;
> > +        clock-names = "fck";
> > +        status = "disabled";  
> 
> status, again.
> 
> > +        dmas = <&edma 53 0>, <&edma 57 0>;
> > +        dma-names = "fifo0", "fifo1";
> > +
> > +        tsc {
> > +            compatible = "ti,am3359-tsc";
> > +            ti,wires = <4>;
> > +            ti,x-plate-resistance = <200>;
> > +            ti,coordinate-readouts = <5>;
> > +            ti,wire-config = <0x00 0x11 0x22 0x33>;
> > +            ti,charge-delay = <0x400>;
> > +        };
> > +    };
> > -- 
> > 2.27.0
> > 
> >   

Thanks,
Miquèl
Miquel Raynal Sept. 2, 2021, 5:45 p.m. UTC | #4
Hi Jonathan,

Jonathan Cameron <jic23@kernel.org> wrote on Mon, 30 Aug 2021 14:36:10
+0100:

> On Wed, 25 Aug 2021 17:24:41 +0200
> Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> 
> > This touchscreen controller is already described in a text file:
> > Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt
> > 
> > After introducing a proper description of the MFD, this is the second
> > step. The file cannot be removed yet as it also contains an ADC
> > description.
> > 
> > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > ---
> >  .../input/touchscreen/ti,am3359-tsc.yaml      | 89 +++++++++++++++++++
> >  1 file changed, 89 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml b/Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml
> > new file mode 100644
> > index 000000000000..2d4ce6d04f53
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml
> > @@ -0,0 +1,89 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/input/touchscreen/ti,am3359-tsc.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: TI AM3359 Touchscreen controller
> > +
> > +maintainers:
> > +  - Miquel Raynal <miquel.raynal@bootlin.com>
> > +
> > +properties:
> > +  compatible:
> > +    const: ti,am3359-tsc
> > +
> > +  ti,wires:
> > +    description: Wires refer to application modes i.e. 4/5/8 wire touchscreen
> > +      support on the platform.
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    enum: [4, 5, 8]
> > +
> > +  ti,x-plate-resistance:
> > +    description: X plate resistance
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +
> > +  ti,coordinate-readouts:
> > +    description: The sequencer supports a total of 16 programmable steps. Each
> > +      step is used to read a single coordinate. A single readout is enough but
> > +      multiple reads can increase the quality. A value of 5 means, 5 reads for
> > +      X, 5 for Y and 2 for Z (always). This utilises 12 of the 16 software steps
> > +      available. The remaining 4 can be used by the ADC.
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    minimum: 1
> > +    maximum: 6
> > +
> > +  ti,wire-config:
> > +    description: Different boards could have a different order for connecting
> > +      wires on touchscreen. We need to provide an 8-bit number where the
> > +      first four bits represent the analog lines and the next 4 bits represent
> > +      positive/negative terminal on that input line. Notations to represent the
> > +      input lines and terminals respectively are as follows, AIN0 = 0, AIN1 = 1
> > +      and so on untill AIN7 = 7. XP = 0, XN = 1, YP = 2, YN = 3.
> > +    $ref: /schemas/types.yaml#/definitions/uint32-array
> > +    minItems: 4
> > +    maxItems: 8
> > +
> > +  ti,charge-delay:
> > +    description: Length of touch screen charge delay step in terms of ADC clock
> > +      cycles. Charge delay value should be large in order to avoid false pen-up
> > +      events. This value effects the overall sampling speed, hence need to be
> > +      kept as low as possible, while avoiding false pen-up event. Start from a
> > +      lower value, say 0x400, and increase value until false pen-up events are
> > +      avoided. The pen-up detection happens immediately after the charge step,
> > +      so this does in fact function as a hardware knob for adjusting the amount
> > +      of "settling time".
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +
> > +required:
> > +  - compatible
> > +  - ti,wires  
> 
> Are these all required?  Seems like the driver will work fine without some
> of them and isn't doing appropriate error checking for their presence..

Well, I don't have a touchscreen so I can't actually verify that it
works without these properties. The logic here is to simply translate
the .txt file and the .txt file states that these properties are
mandatory. But of course if people have one and can test, it would be
good to either add the proper checks to the driver or drop these
properties from the required list. But as far as I am concerned, it is
too risky to do this kind of blind change in a binding file...

Thanks,
Miquèl
Jonathan Cameron Sept. 5, 2021, 11:58 a.m. UTC | #5
On Thu, 2 Sep 2021 19:45:36 +0200
Miquel Raynal <miquel.raynal@bootlin.com> wrote:

> Hi Jonathan,
> 
> Jonathan Cameron <jic23@kernel.org> wrote on Mon, 30 Aug 2021 14:36:10
> +0100:
> 
> > On Wed, 25 Aug 2021 17:24:41 +0200
> > Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> >   
> > > This touchscreen controller is already described in a text file:
> > > Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt
> > > 
> > > After introducing a proper description of the MFD, this is the second
> > > step. The file cannot be removed yet as it also contains an ADC
> > > description.
> > > 
> > > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > > ---
> > >  .../input/touchscreen/ti,am3359-tsc.yaml      | 89 +++++++++++++++++++
> > >  1 file changed, 89 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml
> > > 
> > > diff --git a/Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml b/Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml
> > > new file mode 100644
> > > index 000000000000..2d4ce6d04f53
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml
> > > @@ -0,0 +1,89 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/input/touchscreen/ti,am3359-tsc.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: TI AM3359 Touchscreen controller
> > > +
> > > +maintainers:
> > > +  - Miquel Raynal <miquel.raynal@bootlin.com>
> > > +
> > > +properties:
> > > +  compatible:
> > > +    const: ti,am3359-tsc
> > > +
> > > +  ti,wires:
> > > +    description: Wires refer to application modes i.e. 4/5/8 wire touchscreen
> > > +      support on the platform.
> > > +    $ref: /schemas/types.yaml#/definitions/uint32
> > > +    enum: [4, 5, 8]
> > > +
> > > +  ti,x-plate-resistance:
> > > +    description: X plate resistance
> > > +    $ref: /schemas/types.yaml#/definitions/uint32
> > > +
> > > +  ti,coordinate-readouts:
> > > +    description: The sequencer supports a total of 16 programmable steps. Each
> > > +      step is used to read a single coordinate. A single readout is enough but
> > > +      multiple reads can increase the quality. A value of 5 means, 5 reads for
> > > +      X, 5 for Y and 2 for Z (always). This utilises 12 of the 16 software steps
> > > +      available. The remaining 4 can be used by the ADC.
> > > +    $ref: /schemas/types.yaml#/definitions/uint32
> > > +    minimum: 1
> > > +    maximum: 6
> > > +
> > > +  ti,wire-config:
> > > +    description: Different boards could have a different order for connecting
> > > +      wires on touchscreen. We need to provide an 8-bit number where the
> > > +      first four bits represent the analog lines and the next 4 bits represent
> > > +      positive/negative terminal on that input line. Notations to represent the
> > > +      input lines and terminals respectively are as follows, AIN0 = 0, AIN1 = 1
> > > +      and so on untill AIN7 = 7. XP = 0, XN = 1, YP = 2, YN = 3.
> > > +    $ref: /schemas/types.yaml#/definitions/uint32-array
> > > +    minItems: 4
> > > +    maxItems: 8
> > > +
> > > +  ti,charge-delay:
> > > +    description: Length of touch screen charge delay step in terms of ADC clock
> > > +      cycles. Charge delay value should be large in order to avoid false pen-up
> > > +      events. This value effects the overall sampling speed, hence need to be
> > > +      kept as low as possible, while avoiding false pen-up event. Start from a
> > > +      lower value, say 0x400, and increase value until false pen-up events are
> > > +      avoided. The pen-up detection happens immediately after the charge step,
> > > +      so this does in fact function as a hardware knob for adjusting the amount
> > > +      of "settling time".
> > > +    $ref: /schemas/types.yaml#/definitions/uint32
> > > +
> > > +required:
> > > +  - compatible
> > > +  - ti,wires    
> > 
> > Are these all required?  Seems like the driver will work fine without some
> > of them and isn't doing appropriate error checking for their presence..  
> 
> Well, I don't have a touchscreen so I can't actually verify that it
> works without these properties. The logic here is to simply translate
> the .txt file and the .txt file states that these properties are
> mandatory. But of course if people have one and can test, it would be
> good to either add the proper checks to the driver or drop these
> properties from the required list. But as far as I am concerned, it is
> too risky to do this kind of blind change in a binding file...

Fair enough!
> 
> Thanks,
> Miquèl
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml b/Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml
new file mode 100644
index 000000000000..2d4ce6d04f53
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml
@@ -0,0 +1,89 @@ 
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/touchscreen/ti,am3359-tsc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: TI AM3359 Touchscreen controller
+
+maintainers:
+  - Miquel Raynal <miquel.raynal@bootlin.com>
+
+properties:
+  compatible:
+    const: ti,am3359-tsc
+
+  ti,wires:
+    description: Wires refer to application modes i.e. 4/5/8 wire touchscreen
+      support on the platform.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [4, 5, 8]
+
+  ti,x-plate-resistance:
+    description: X plate resistance
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  ti,coordinate-readouts:
+    description: The sequencer supports a total of 16 programmable steps. Each
+      step is used to read a single coordinate. A single readout is enough but
+      multiple reads can increase the quality. A value of 5 means, 5 reads for
+      X, 5 for Y and 2 for Z (always). This utilises 12 of the 16 software steps
+      available. The remaining 4 can be used by the ADC.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 1
+    maximum: 6
+
+  ti,wire-config:
+    description: Different boards could have a different order for connecting
+      wires on touchscreen. We need to provide an 8-bit number where the
+      first four bits represent the analog lines and the next 4 bits represent
+      positive/negative terminal on that input line. Notations to represent the
+      input lines and terminals respectively are as follows, AIN0 = 0, AIN1 = 1
+      and so on untill AIN7 = 7. XP = 0, XN = 1, YP = 2, YN = 3.
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    minItems: 4
+    maxItems: 8
+
+  ti,charge-delay:
+    description: Length of touch screen charge delay step in terms of ADC clock
+      cycles. Charge delay value should be large in order to avoid false pen-up
+      events. This value effects the overall sampling speed, hence need to be
+      kept as low as possible, while avoiding false pen-up event. Start from a
+      lower value, say 0x400, and increase value until false pen-up events are
+      avoided. The pen-up detection happens immediately after the charge step,
+      so this does in fact function as a hardware knob for adjusting the amount
+      of "settling time".
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+required:
+  - compatible
+  - ti,wires
+  - ti,x-plate-resistance
+  - ti,coordinate-readouts
+  - ti,wire-config
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+
+    tscadc: tscadc@0 {
+        compatible = "ti,am3359-tscadc";
+        reg = <0x0 0x1000>;
+        interrupts = <GIC_SPI 16 IRQ_TYPE_LEVEL_HIGH>;
+        clocks = <&adc_tsc_fck>;
+        clock-names = "fck";
+        status = "disabled";
+        dmas = <&edma 53 0>, <&edma 57 0>;
+        dma-names = "fifo0", "fifo1";
+
+        tsc {
+            compatible = "ti,am3359-tsc";
+            ti,wires = <4>;
+            ti,x-plate-resistance = <200>;
+            ti,coordinate-readouts = <5>;
+            ti,wire-config = <0x00 0x11 0x22 0x33>;
+            ti,charge-delay = <0x400>;
+        };
+    };