[PATCH v5 0/8] add z1 and z2 channels support for resistive-adc-touch driver

[PATCH v5 0/8] add z1 and z2 channels support for resistive-adc-touch driver

[Oleksij Rempel]

changes v5:
- fix validate for other DT examples.
- add Reviewed-by: Rob Herring <robh@kernel.org> to some of the patches

changes v4:
- resistive-adc-touch: remove unused variable

changes v3:
- yaml: fix validation for channel names
- yaml: add nodename validation

changes v2:
- add yaml conversion patch to this series
- reword commit message for the last patch
- fix possible overflow on the buffer dispatcher

Oleksij Rempel (8):
  dt-bindings: input: touchscreen: iqs626a: chnage node name to pass
    validation
  dt-bindings: input: touchscreen: edt-ft5x06: chnage node name to pass
    validation
  dt-bindings: input: touchscreen: goodix: chnage node name to pass
    validation
  dt-bindings: touchscreen: validate nodename
  dt-bindings: touchscreen: Convert resistive-adc-touch binding to json
    schema
  dt-bindings: touchscreen: add touchscreen-x/y-plate-ohms property
  dt-bindings: touchscreen: resistive-adc-touch: add support for z1 and
    z2 channels
  Input: resistive-adc-touch: add support for z1 and z2 channels

 .../devicetree/bindings/input/iqs626a.yaml    |   2 +-
 .../input/touchscreen/edt-ft5x06.yaml         |   2 +-
 .../bindings/input/touchscreen/goodix.yaml    |   2 +-
 .../input/touchscreen/resistive-adc-touch.txt |  33 ----
 .../touchscreen/resistive-adc-touch.yaml      |  86 +++++++++++
 .../input/touchscreen/touchscreen.yaml        |   9 ++
 .../input/touchscreen/resistive-adc-touch.c   | 142 ++++++++++++++++--
 7 files changed, 226 insertions(+), 50 deletions(-)
 delete mode 100644 Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.txt
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml

-- 
2.29.2

[PATCH v5 1/8] dt-bindings: input: touchscreen: iqs626a: chnage node name to pass validation

[Oleksij Rempel]

Change node name from iqs626a -> touchscreen to pass dt_binding_check.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 Documentation/devicetree/bindings/input/iqs626a.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/input/iqs626a.yaml b/Documentation/devicetree/bindings/input/iqs626a.yaml
index 0cb736c541c9..ea4f04e2d3ad 100644
--- a/Documentation/devicetree/bindings/input/iqs626a.yaml
+++ b/Documentation/devicetree/bindings/input/iqs626a.yaml
@@ -751,7 +751,7 @@ examples:
             #address-cells = <1>;
             #size-cells = <0>;
 
-            iqs626a@44 {
+            touchscreen@44 {
                     #address-cells = <1>;
                     #size-cells = <0>;
 
-- 
2.29.2

Re: [PATCH v5 1/8] dt-bindings: input: touchscreen: iqs626a: chnage node name to pass validation

[Jonathan Cameron]

Change typo in title.


On Fri, 21 May 2021 06:45:18 +0200
Oleksij Rempel <o.rempel@pengutronix.de> wrote:

> Change node name from iqs626a -> touchscreen to pass dt_binding_check.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> ---
>  Documentation/devicetree/bindings/input/iqs626a.yaml | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/input/iqs626a.yaml b/Documentation/devicetree/bindings/input/iqs626a.yaml
> index 0cb736c541c9..ea4f04e2d3ad 100644
> --- a/Documentation/devicetree/bindings/input/iqs626a.yaml
> +++ b/Documentation/devicetree/bindings/input/iqs626a.yaml
> @@ -751,7 +751,7 @@ examples:
>              #address-cells = <1>;
>              #size-cells = <0>;
>  
> -            iqs626a@44 {
> +            touchscreen@44 {
>                      #address-cells = <1>;
>                      #size-cells = <0>;
>  

Re: [PATCH v5 1/8] dt-bindings: input: touchscreen: iqs626a: chnage node name to pass validation

[Rob Herring]

On Fri, 21 May 2021 06:45:18 +0200, Oleksij Rempel wrote:
> Change node name from iqs626a -> touchscreen to pass dt_binding_check.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> ---
>  Documentation/devicetree/bindings/input/iqs626a.yaml | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Acked-by: Rob Herring <robh@kernel.org>

Re: [PATCH v5 1/8] dt-bindings: input: touchscreen: iqs626a: chnage node name to pass validation

[Jeff LaBundy]

Hi Oleksij and Rob,

I disagree with this patch; the device is neither a touchscreen nor
does the example include any touchscreen properties. The end result
is confusing.

On Fri, May 21, 2021 at 12:08:30PM -0500, Rob Herring wrote:
> On Fri, 21 May 2021 06:45:18 +0200, Oleksij Rempel wrote:
> > Change node name from iqs626a -> touchscreen to pass dt_binding_check.
> > 
> > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> > ---
> >  Documentation/devicetree/bindings/input/iqs626a.yaml | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> 
> Acked-by: Rob Herring <robh@kernel.org>

What is the failure returned by dt_binding_check? Is it because of
the reference to touchscreen.yaml? If so, I'd rather we update the
tool instead of appease it.

This device leverages the touchscreen helpers for axis swapping or
inversion in 'trackpad' mode, which any input device is free to do
starting with 5.13.

Kind regards,
Jeff LaBundy

[PATCH v5 2/8] dt-bindings: input: touchscreen: edt-ft5x06: chnage node name to pass validation

[Oleksij Rempel]

Change node name from edt-ft5x06 -> touchscreen to pass dt_binding_check.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 .../devicetree/bindings/input/touchscreen/edt-ft5x06.yaml       | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.yaml b/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.yaml
index bfc3a8b5e118..0c43cac8c66f 100644
--- a/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.yaml
+++ b/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.yaml
@@ -107,7 +107,7 @@ examples:
     i2c {
       #address-cells = <1>;
       #size-cells = <0>;
-      edt-ft5x06@38 {
+      touchscreen@38 {
         compatible = "edt,edt-ft5406";
         reg = <0x38>;
         interrupt-parent = <&gpio2>;
-- 
2.29.2

Re: [PATCH v5 2/8] dt-bindings: input: touchscreen: edt-ft5x06: chnage node name to pass validation

[Rob Herring]

On Fri, 21 May 2021 06:45:19 +0200, Oleksij Rempel wrote:
> Change node name from edt-ft5x06 -> touchscreen to pass dt_binding_check.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> ---
>  .../devicetree/bindings/input/touchscreen/edt-ft5x06.yaml       | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Acked-by: Rob Herring <robh@kernel.org>

[PATCH v5 3/8] dt-bindings: input: touchscreen: goodix: chnage node name to pass validation

[Oleksij Rempel]

Change node name from gt928 -> touchscreen to pass dt_binding_check.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 Documentation/devicetree/bindings/input/touchscreen/goodix.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/input/touchscreen/goodix.yaml b/Documentation/devicetree/bindings/input/touchscreen/goodix.yaml
index 93f2ce3130ae..7503e6f0b8a0 100644
--- a/Documentation/devicetree/bindings/input/touchscreen/goodix.yaml
+++ b/Documentation/devicetree/bindings/input/touchscreen/goodix.yaml
@@ -67,7 +67,7 @@ examples:
     i2c {
       #address-cells = <1>;
       #size-cells = <0>;
-      gt928@5d {
+      touchscreen@5d {
         compatible = "goodix,gt928";
         reg = <0x5d>;
         interrupt-parent = <&gpio>;
-- 
2.29.2

Re: [PATCH v5 3/8] dt-bindings: input: touchscreen: goodix: chnage node name to pass validation

[Rob Herring]

On Fri, May 21, 2021 at 06:45:20AM +0200, Oleksij Rempel wrote:
> Change node name from gt928 -> touchscreen to pass dt_binding_check.

Well, at least you were consistent on the subject. :)

> 
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> ---
>  Documentation/devicetree/bindings/input/touchscreen/goodix.yaml | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Acked-by: Rob Herring <robh@kernel.org>

[PATCH v5 4/8] dt-bindings: touchscreen: validate nodename

[Oleksij Rempel]

Validate touchscreen nodes. Make sure it is named touchscreen*.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 .../devicetree/bindings/input/touchscreen/touchscreen.yaml     | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/input/touchscreen/touchscreen.yaml b/Documentation/devicetree/bindings/input/touchscreen/touchscreen.yaml
index 046ace461cc9..057e1063759c 100644
--- a/Documentation/devicetree/bindings/input/touchscreen/touchscreen.yaml
+++ b/Documentation/devicetree/bindings/input/touchscreen/touchscreen.yaml
@@ -10,6 +10,9 @@ maintainers:
   - Dmitry Torokhov <dmitry.torokhov@gmail.com>
 
 properties:
+  $nodename:
+    pattern: "^touchscreen(@.*)?$"
+
   touchscreen-min-x:
     description: minimum x coordinate reported
     $ref: /schemas/types.yaml#/definitions/uint32
-- 
2.29.2

Re: [PATCH v5 4/8] dt-bindings: touchscreen: validate nodename

[Jonathan Cameron]

On Fri, 21 May 2021 06:45:21 +0200
Oleksij Rempel <o.rempel@pengutronix.de> wrote:

> Validate touchscreen nodes. Make sure it is named touchscreen*.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>

Feels like this should be two separate patch sets...
The node name one, and then the stuff for the resistive touch screen. 

> ---
>  .../devicetree/bindings/input/touchscreen/touchscreen.yaml     | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/input/touchscreen/touchscreen.yaml b/Documentation/devicetree/bindings/input/touchscreen/touchscreen.yaml
> index 046ace461cc9..057e1063759c 100644
> --- a/Documentation/devicetree/bindings/input/touchscreen/touchscreen.yaml
> +++ b/Documentation/devicetree/bindings/input/touchscreen/touchscreen.yaml
> @@ -10,6 +10,9 @@ maintainers:
>    - Dmitry Torokhov <dmitry.torokhov@gmail.com>
>  
>  properties:
> +  $nodename:
> +    pattern: "^touchscreen(@.*)?$"
> +
>    touchscreen-min-x:
>      description: minimum x coordinate reported
>      $ref: /schemas/types.yaml#/definitions/uint32

Re: [PATCH v5 4/8] dt-bindings: touchscreen: validate nodename

[Rob Herring]

On Fri, 21 May 2021 06:45:21 +0200, Oleksij Rempel wrote:
> Validate touchscreen nodes. Make sure it is named touchscreen*.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> ---
>  .../devicetree/bindings/input/touchscreen/touchscreen.yaml     | 3 +++
>  1 file changed, 3 insertions(+)
> 

Acked-by: Rob Herring <robh@kernel.org>

Re: [PATCH v5 4/8] dt-bindings: touchscreen: validate nodename

[Dmitry Torokhov]

On Fri, May 21, 2021 at 12:18:23PM -0500, Rob Herring wrote:
> On Fri, 21 May 2021 06:45:21 +0200, Oleksij Rempel wrote:
> > Validate touchscreen nodes. Make sure it is named touchscreen*.
> > 
> > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> > ---
> >  .../devicetree/bindings/input/touchscreen/touchscreen.yaml     | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> 
> Acked-by: Rob Herring <robh@kernel.org>

These bindings are used for devices other than touchscreens (touchpads
and other touch controllers that are not touchscreens), so forcing them
to be named "touchscreen*" is wrong. In fact, I'd like to allow using
"touch-*" property names as aliases for "touchscreen-*" properties.

Thanks.

-- 
Dmitry

[PATCH v5 5/8] dt-bindings: touchscreen: Convert resistive-adc-touch binding to json schema

[Oleksij Rempel]

Convert the resistive-adc-touch binding to DT schema format using json-schema.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Rob Herring <robh@kernel.org>
---
 .../input/touchscreen/resistive-adc-touch.txt | 33 ---------
 .../touchscreen/resistive-adc-touch.yaml      | 70 +++++++++++++++++++
 2 files changed, 70 insertions(+), 33 deletions(-)
 delete mode 100644 Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.txt
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml

diff --git a/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.txt b/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.txt
deleted file mode 100644
index af5223bb5bdd..000000000000
--- a/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.txt
+++ /dev/null
@@ -1,33 +0,0 @@
-Generic resistive touchscreen ADC
-
-Required properties:
-
- - compatible: must be "resistive-adc-touch"
-The device must be connected to an ADC device that provides channels for
-position measurement and optional pressure.
-Refer to
-https://github.com/devicetree-org/dt-schema/blob/master/schemas/iio/iio-consumer.yaml
-for details
-
- - iio-channels: must have at least two channels connected to an ADC device.
-These should correspond to the channels exposed by the ADC device and should
-have the right index as the ADC device registers them. These channels
-represent the relative position on the "x" and "y" axes.
- - iio-channel-names: must have all the channels' names. Mandatory channels
-are "x" and "y".
-
-Optional properties:
- - iio-channels: The third channel named "pressure" is optional and can be
-used if the ADC device also measures pressure besides position.
-If this channel is missing, pressure will be ignored and the touchscreen
-will only report position.
- - iio-channel-names: optional channel named "pressure".
-
-Example:
-
-	resistive_touch: resistive_touch {
-		compatible = "resistive-adc-touch";
-		touchscreen-min-pressure = <50000>;
-		io-channels = <&adc 24>, <&adc 25>, <&adc 26>;
-		io-channel-names = "x", "y", "pressure";
-	};
diff --git a/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml b/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml
new file mode 100644
index 000000000000..38b4cbee9429
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml
@@ -0,0 +1,70 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/touchscreen/resistive-adc-touch.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic resistive touchscreen ADC
+
+maintainers:
+  - Oleksij Rempel <o.rempel@pengutronix.de>
+
+description: |
+  Generic ADC based resistive touchscreen controller
+  The device must be connected to an ADC device that provides channels for
+  position measurement and optional pressure.
+
+allOf:
+  - $ref: touchscreen.yaml#
+
+properties:
+  compatible:
+    const: resistive-adc-touch
+
+  io-channels:
+    minItems: 2
+    items:
+      - description: x
+      - description: y
+      - description: pressure (optional)
+
+  io-channel-names:
+    oneOf:
+      - items:
+          - enum: [x, y]
+          - enum: [x, y]
+      - items:
+          - enum: [x, y, pressure]
+          - enum: [x, y, pressure]
+          - enum: [x, y, pressure]
+
+  touchscreen-size-x: true
+  touchscreen-size-y: true
+  touchscreen-fuzz-x: true
+  touchscreen-fuzz-y: true
+  touchscreen-inverted-x: true
+  touchscreen-inverted-y: true
+  touchscreen-swapped-x-y: true
+  touchscreen-min-pressure: true
+
+additionalProperties: false
+
+required:
+  - compatible
+  - io-channels
+  - io-channel-names
+
+examples:
+  - |
+    touchscreen {
+      compatible = "resistive-adc-touch";
+      io-channels = <&adc 24>, <&adc 25>;
+      io-channel-names = "y", "x";
+    };
+  - |
+    touchscreen {
+      compatible = "resistive-adc-touch";
+      touchscreen-min-pressure = <50000>;
+      io-channels = <&adc 24>, <&adc 25>, <&adc 26>;
+      io-channel-names = "y", "pressure", "x";
+    };
-- 
2.29.2

Re: [PATCH v5 5/8] dt-bindings: touchscreen: Convert resistive-adc-touch binding to json schema

[Jonathan Cameron]

On Fri, 21 May 2021 06:45:22 +0200
Oleksij Rempel <o.rempel@pengutronix.de> wrote:

> Convert the resistive-adc-touch binding to DT schema format using json-schema.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> Reviewed-by: Rob Herring <robh@kernel.org>
Looks good to me.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  .../input/touchscreen/resistive-adc-touch.txt | 33 ---------
>  .../touchscreen/resistive-adc-touch.yaml      | 70 +++++++++++++++++++
>  2 files changed, 70 insertions(+), 33 deletions(-)
>  delete mode 100644 Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.txt
>  create mode 100644 Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml
> 
> diff --git a/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.txt b/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.txt
> deleted file mode 100644
> index af5223bb5bdd..000000000000
> --- a/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.txt
> +++ /dev/null
> @@ -1,33 +0,0 @@
> -Generic resistive touchscreen ADC
> -
> -Required properties:
> -
> - - compatible: must be "resistive-adc-touch"
> -The device must be connected to an ADC device that provides channels for
> -position measurement and optional pressure.
> -Refer to
> -https://github.com/devicetree-org/dt-schema/blob/master/schemas/iio/iio-consumer.yaml
> -for details
> -
> - - iio-channels: must have at least two channels connected to an ADC device.
> -These should correspond to the channels exposed by the ADC device and should
> -have the right index as the ADC device registers them. These channels
> -represent the relative position on the "x" and "y" axes.
> - - iio-channel-names: must have all the channels' names. Mandatory channels
> -are "x" and "y".
> -
> -Optional properties:
> - - iio-channels: The third channel named "pressure" is optional and can be
> -used if the ADC device also measures pressure besides position.
> -If this channel is missing, pressure will be ignored and the touchscreen
> -will only report position.
> - - iio-channel-names: optional channel named "pressure".
> -
> -Example:
> -
> -	resistive_touch: resistive_touch {
> -		compatible = "resistive-adc-touch";
> -		touchscreen-min-pressure = <50000>;
> -		io-channels = <&adc 24>, <&adc 25>, <&adc 26>;
> -		io-channel-names = "x", "y", "pressure";
> -	};
> diff --git a/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml b/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml
> new file mode 100644
> index 000000000000..38b4cbee9429
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml
> @@ -0,0 +1,70 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/input/touchscreen/resistive-adc-touch.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Generic resistive touchscreen ADC
> +
> +maintainers:
> +  - Oleksij Rempel <o.rempel@pengutronix.de>
> +
> +description: |
> +  Generic ADC based resistive touchscreen controller
> +  The device must be connected to an ADC device that provides channels for
> +  position measurement and optional pressure.
> +
> +allOf:
> +  - $ref: touchscreen.yaml#
> +
> +properties:
> +  compatible:
> +    const: resistive-adc-touch
> +
> +  io-channels:
> +    minItems: 2
> +    items:
> +      - description: x
> +      - description: y
> +      - description: pressure (optional)
> +
> +  io-channel-names:
> +    oneOf:
> +      - items:
> +          - enum: [x, y]
> +          - enum: [x, y]
> +      - items:
> +          - enum: [x, y, pressure]
> +          - enum: [x, y, pressure]
> +          - enum: [x, y, pressure]
> +
> +  touchscreen-size-x: true
> +  touchscreen-size-y: true
> +  touchscreen-fuzz-x: true
> +  touchscreen-fuzz-y: true
> +  touchscreen-inverted-x: true
> +  touchscreen-inverted-y: true
> +  touchscreen-swapped-x-y: true
> +  touchscreen-min-pressure: true
> +
> +additionalProperties: false
> +
> +required:
> +  - compatible
> +  - io-channels
> +  - io-channel-names
> +
> +examples:
> +  - |
> +    touchscreen {
> +      compatible = "resistive-adc-touch";
> +      io-channels = <&adc 24>, <&adc 25>;
> +      io-channel-names = "y", "x";
> +    };
> +  - |
> +    touchscreen {
> +      compatible = "resistive-adc-touch";
> +      touchscreen-min-pressure = <50000>;
> +      io-channels = <&adc 24>, <&adc 25>, <&adc 26>;
> +      io-channel-names = "y", "pressure", "x";
> +    };

[PATCH v5 6/8] dt-bindings: touchscreen: add touchscreen-x/y-plate-ohms property

[Oleksij Rempel]

Te calculate the pressure on a restrictive touchscreen we need need to
know resistance at least of X plate. Some calculations need to use both
X and Y values.
So, add generic properties which can be used by all drivers

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Rob Herring <robh@kernel.org>
---
 .../devicetree/bindings/input/touchscreen/touchscreen.yaml  | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/input/touchscreen/touchscreen.yaml b/Documentation/devicetree/bindings/input/touchscreen/touchscreen.yaml
index 057e1063759c..2d7b039ce47f 100644
--- a/Documentation/devicetree/bindings/input/touchscreen/touchscreen.yaml
+++ b/Documentation/devicetree/bindings/input/touchscreen/touchscreen.yaml
@@ -77,6 +77,12 @@ properties:
   touchscreen-y-mm:
     description: vertical length in mm of the touchscreen
 
+  touchscreen-x-plate-ohms:
+    description: Resistance of the X-plate in Ohms
+
+  touchscreen-y-plate-ohms:
+    description: Resistance of the Y-plate in Ohms
+
 dependencies:
   touchscreen-size-x: [ touchscreen-size-y ]
   touchscreen-size-y: [ touchscreen-size-x ]
-- 
2.29.2

[PATCH v5 7/8] dt-bindings: touchscreen: resistive-adc-touch: add support for z1 and z2 channels

[Oleksij Rempel]

For pressure calculation based on plates resistance we need some additional
properties:
- z1 and z2 channels with additional measurements between plates
- actual resistance of the touchscreen. Currently we use only
  X-resistance.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Rob Herring <robh@kernel.org>
---
 .../input/touchscreen/resistive-adc-touch.yaml   | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml b/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml
index 38b4cbee9429..7fc22a403d48 100644
--- a/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml
+++ b/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml
@@ -27,6 +27,8 @@ properties:
       - description: x
       - description: y
       - description: pressure (optional)
+      - description: z1 (optional)
+      - description: z2 (optional)
 
   io-channel-names:
     oneOf:
@@ -37,6 +39,11 @@ properties:
           - enum: [x, y, pressure]
           - enum: [x, y, pressure]
           - enum: [x, y, pressure]
+      - items:
+          - enum: [x, y, z1, z2]
+          - enum: [x, y, z1, z2]
+          - enum: [x, y, z1, z2]
+          - enum: [x, y, z1, z2]
 
   touchscreen-size-x: true
   touchscreen-size-y: true
@@ -46,6 +53,7 @@ properties:
   touchscreen-inverted-y: true
   touchscreen-swapped-x-y: true
   touchscreen-min-pressure: true
+  touchscreen-x-plate-ohms: true
 
 additionalProperties: false
 
@@ -68,3 +76,11 @@ examples:
       io-channels = <&adc 24>, <&adc 25>, <&adc 26>;
       io-channel-names = "y", "pressure", "x";
     };
+  - |
+    touchscreen {
+      compatible = "resistive-adc-touch";
+      touchscreen-min-pressure = <50000>;
+      io-channels = <&adc 1>, <&adc 2>, <&adc 3>, <&adc 4>;
+      io-channel-names = "x", "z1", "z2", "y";
+      touchscreen-x-plate-ohms = <800>;
+    };
-- 
2.29.2

[PATCH v5 8/8] Input: resistive-adc-touch: add support for z1 and z2 channels

[Oleksij Rempel]

This patch adds support for the z1 and z2 channels. These are used to
calculate the applied pressure. As there is no common order of the
individual channels of a resistive touch ADC, support for
io-channel-names is added (although the DT bindings stated the
driver already supports these).

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 .../input/touchscreen/resistive-adc-touch.c   | 142 ++++++++++++++++--
 1 file changed, 128 insertions(+), 14 deletions(-)

diff --git a/drivers/input/touchscreen/resistive-adc-touch.c b/drivers/input/touchscreen/resistive-adc-touch.c
index e50af30183f4..fa90005b7bc9 100644
--- a/drivers/input/touchscreen/resistive-adc-touch.c
+++ b/drivers/input/touchscreen/resistive-adc-touch.c
@@ -20,7 +20,18 @@
 
 #define DRIVER_NAME					"resistive-adc-touch"
 #define GRTS_DEFAULT_PRESSURE_MIN			50000
+#define GRTS_DEFAULT_PRESSURE_MAX			65535
 #define GRTS_MAX_POS_MASK				GENMASK(11, 0)
+#define GRTS_MAX_CHANNELS				4
+
+enum grts_ch_type {
+	GRTS_CH_NONE = 0,
+	GRTS_CH_X,
+	GRTS_CH_Y,
+	GRTS_CH_PRESSURE,
+	GRTS_CH_Z1,
+	GRTS_CH_Z2,
+};
 
 /**
  * struct grts_state - generic resistive touch screen information struct
@@ -33,24 +44,61 @@
  */
 struct grts_state {
 	u32				pressure_min;
+	u32				x_plate_ohms;
 	bool				pressure;
 	struct iio_channel		*iio_chans;
 	struct iio_cb_buffer		*iio_cb;
 	struct input_dev		*input;
 	struct touchscreen_properties	prop;
+	u8				ch[GRTS_MAX_CHANNELS];
 };
 
 static int grts_cb(const void *data, void *private)
 {
 	const u16 *touch_info = data;
 	struct grts_state *st = private;
-	unsigned int x, y, press = 0x0;
+	unsigned int x, y, press = 0, z1 = 0, z2;
+	unsigned int Rt, i;
+
+	for (i = 0; i < ARRAY_SIZE(st->ch) && st->ch[i] != GRTS_CH_NONE; i++) {
+		switch (st->ch[i]) {
+		case GRTS_CH_X:
+			x = touch_info[i];
+			break;
+		case GRTS_CH_Y:
+			y = touch_info[i];
+			break;
+		case GRTS_CH_PRESSURE:
+			press = touch_info[i];
+			break;
+		case GRTS_CH_Z1:
+			z1 = touch_info[i];
+			break;
+		case GRTS_CH_Z2:
+			z2 = touch_info[i];
+			break;
+		case GRTS_CH_NONE:
+			break;
+		}
+	}
 
-	/* channel data coming in buffer in the order below */
-	x = touch_info[0];
-	y = touch_info[1];
-	if (st->pressure)
-		press = touch_info[2];
+	if (z1) {
+		Rt = z2;
+		Rt -= z1;
+		Rt *= st->x_plate_ohms;
+		Rt = DIV_ROUND_CLOSEST(Rt, 16);
+		Rt *= x;
+		Rt /= z1;
+		Rt = DIV_ROUND_CLOSEST(Rt, 256);
+		/*
+		 * On increased pressure the resistance (Rt) is decreasing
+		 * so, convert values to make it looks as real pressure.
+		 */
+		if (Rt < GRTS_DEFAULT_PRESSURE_MAX)
+			press = GRTS_DEFAULT_PRESSURE_MAX - Rt;
+		else
+			press = 0;
+	}
 
 	if ((!x && !y) || (st->pressure && (press < st->pressure_min))) {
 		/* report end of touch */
@@ -94,12 +142,77 @@ static void grts_disable(void *data)
 	iio_channel_release_all_cb(data);
 }
 
+static int grts_get_properties(struct grts_state *st, struct device *dev)
+{
+	int idx, error;
+
+	idx = device_property_match_string(dev, "io-channel-names", "x");
+	if (idx < 0)
+		return idx;
+
+	if (idx >= ARRAY_SIZE(st->ch))
+		return -EOVERFLOW;
+
+	st->ch[idx] = GRTS_CH_X;
+
+	idx = device_property_match_string(dev, "io-channel-names", "y");
+	if (idx < 0)
+		return idx;
+
+	if (idx >= ARRAY_SIZE(st->ch))
+		return -EOVERFLOW;
+
+	st->ch[idx] = GRTS_CH_Y;
+
+	/* pressure is optional */
+	idx = device_property_match_string(dev, "io-channel-names", "pressure");
+	if (idx >= 0) {
+		if (idx >= ARRAY_SIZE(st->ch))
+			return -EOVERFLOW;
+
+		st->ch[idx] = GRTS_CH_PRESSURE;
+		st->pressure = true;
+
+		return 0;
+	}
+
+	/* if no pressure is defined, try optional z1 + z2 */
+	idx = device_property_match_string(dev, "io-channel-names", "z1");
+	if (idx < 0)
+		return 0;
+
+	if (idx >= ARRAY_SIZE(st->ch))
+		return -EOVERFLOW;
+
+	st->ch[idx] = GRTS_CH_Z1;
+
+	/* if z1 is provided z2 is not optional */
+	idx = device_property_match_string(dev, "io-channel-names", "z2");
+	if (idx < 0)
+		return idx;
+
+	if (idx >= ARRAY_SIZE(st->ch))
+		return -EOVERFLOW;
+
+	st->ch[idx] = GRTS_CH_Z2;
+	st->pressure = true;
+
+	error = device_property_read_u32(dev,
+					 "touchscreen-x-plate-ohms",
+					 &st->x_plate_ohms);
+	if (error) {
+		dev_err(dev, "can't get touchscreen-x-plate-ohms property\n");
+		return error;
+	}
+
+	return 0;
+}
+
 static int grts_probe(struct platform_device *pdev)
 {
 	struct grts_state *st;
 	struct input_dev *input;
 	struct device *dev = &pdev->dev;
-	struct iio_channel *chan;
 	int error;
 
 	st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL);
@@ -115,12 +228,13 @@ static int grts_probe(struct platform_device *pdev)
 		return error;
 	}
 
-	chan = &st->iio_chans[0];
-	st->pressure = false;
-	while (chan && chan->indio_dev) {
-		if (!strcmp(chan->channel->datasheet_name, "pressure"))
-			st->pressure = true;
-		chan++;
+	if (!device_property_present(dev, "io-channel-names"))
+		return -ENODEV;
+
+	error = grts_get_properties(st, dev);
+	if (error) {
+		dev_err(dev, "Failed to parse properties\n");
+		return error;
 	}
 
 	if (st->pressure) {
@@ -148,7 +262,7 @@ static int grts_probe(struct platform_device *pdev)
 	input_set_abs_params(input, ABS_Y, 0, GRTS_MAX_POS_MASK - 1, 0, 0);
 	if (st->pressure)
 		input_set_abs_params(input, ABS_PRESSURE, st->pressure_min,
-				     0xffff, 0, 0);
+				     GRTS_DEFAULT_PRESSURE_MAX, 0, 0);
 
 	input_set_capability(input, EV_KEY, BTN_TOUCH);
 
-- 
2.29.2

Re: [PATCH v5 8/8] Input: resistive-adc-touch: add support for z1 and z2 channels

[Jonathan Cameron]

On Fri, 21 May 2021 06:45:25 +0200
Oleksij Rempel <o.rempel@pengutronix.de> wrote:

> This patch adds support for the z1 and z2 channels. These are used to
> calculate the applied pressure. As there is no common order of the
> individual channels of a resistive touch ADC, support for
> io-channel-names is added (although the DT bindings stated the
> driver already supports these).
> 
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>

One minor comment inline, but otherwise looks good to me.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Would be nice at some point to make this handle channels that
aren't 16 bits, but that can be a job for another day.

Jonathan

> ---
>  .../input/touchscreen/resistive-adc-touch.c   | 142 ++++++++++++++++--
>  1 file changed, 128 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/resistive-adc-touch.c b/drivers/input/touchscreen/resistive-adc-touch.c
> index e50af30183f4..fa90005b7bc9 100644
> --- a/drivers/input/touchscreen/resistive-adc-touch.c
> +++ b/drivers/input/touchscreen/resistive-adc-touch.c
> @@ -20,7 +20,18 @@
>  
>  #define DRIVER_NAME					"resistive-adc-touch"
>  #define GRTS_DEFAULT_PRESSURE_MIN			50000
> +#define GRTS_DEFAULT_PRESSURE_MAX			65535
>  #define GRTS_MAX_POS_MASK				GENMASK(11, 0)
> +#define GRTS_MAX_CHANNELS				4
> +
> +enum grts_ch_type {
> +	GRTS_CH_NONE = 0,
> +	GRTS_CH_X,
> +	GRTS_CH_Y,
> +	GRTS_CH_PRESSURE,
> +	GRTS_CH_Z1,
> +	GRTS_CH_Z2,
> +};
>  
>  /**
>   * struct grts_state - generic resistive touch screen information struct
> @@ -33,24 +44,61 @@
>   */
>  struct grts_state {
>  	u32				pressure_min;
> +	u32				x_plate_ohms;
>  	bool				pressure;
>  	struct iio_channel		*iio_chans;
>  	struct iio_cb_buffer		*iio_cb;
>  	struct input_dev		*input;
>  	struct touchscreen_properties	prop;
> +	u8				ch[GRTS_MAX_CHANNELS];
>  };
>  
>  static int grts_cb(const void *data, void *private)
>  {
>  	const u16 *touch_info = data;
>  	struct grts_state *st = private;
> -	unsigned int x, y, press = 0x0;
> +	unsigned int x, y, press = 0, z1 = 0, z2;
> +	unsigned int Rt, i;
> +
> +	for (i = 0; i < ARRAY_SIZE(st->ch) && st->ch[i] != GRTS_CH_NONE; i++) {
> +		switch (st->ch[i]) {
> +		case GRTS_CH_X:
> +			x = touch_info[i];
> +			break;
> +		case GRTS_CH_Y:
> +			y = touch_info[i];
> +			break;
> +		case GRTS_CH_PRESSURE:
> +			press = touch_info[i];
> +			break;
> +		case GRTS_CH_Z1:
> +			z1 = touch_info[i];
> +			break;
> +		case GRTS_CH_Z2:
> +			z2 = touch_info[i];
> +			break;
> +		case GRTS_CH_NONE:

Loop condition above prevents this.   I guess you might get a warning though
so if this is just warning suppression then add a comment to say so to
make sure it isn't removed.

> +			break;
> +		}
> +	}
>  
> -	/* channel data coming in buffer in the order below */
> -	x = touch_info[0];
> -	y = touch_info[1];
> -	if (st->pressure)
> -		press = touch_info[2];
> +	if (z1) {
> +		Rt = z2;
> +		Rt -= z1;
> +		Rt *= st->x_plate_ohms;
> +		Rt = DIV_ROUND_CLOSEST(Rt, 16);
> +		Rt *= x;
> +		Rt /= z1;
> +		Rt = DIV_ROUND_CLOSEST(Rt, 256);
> +		/*
> +		 * On increased pressure the resistance (Rt) is decreasing
> +		 * so, convert values to make it looks as real pressure.
> +		 */
> +		if (Rt < GRTS_DEFAULT_PRESSURE_MAX)
> +			press = GRTS_DEFAULT_PRESSURE_MAX - Rt;
> +		else
> +			press = 0;
> +	}
>  
>  	if ((!x && !y) || (st->pressure && (press < st->pressure_min))) {
>  		/* report end of touch */
> @@ -94,12 +142,77 @@ static void grts_disable(void *data)
>  	iio_channel_release_all_cb(data);
>  }
>  
> +static int grts_get_properties(struct grts_state *st, struct device *dev)
> +{
> +	int idx, error;
> +
> +	idx = device_property_match_string(dev, "io-channel-names", "x");
> +	if (idx < 0)
> +		return idx;
> +
> +	if (idx >= ARRAY_SIZE(st->ch))
> +		return -EOVERFLOW;
> +
> +	st->ch[idx] = GRTS_CH_X;
> +
> +	idx = device_property_match_string(dev, "io-channel-names", "y");
> +	if (idx < 0)
> +		return idx;
> +
> +	if (idx >= ARRAY_SIZE(st->ch))
> +		return -EOVERFLOW;
> +
> +	st->ch[idx] = GRTS_CH_Y;
> +
> +	/* pressure is optional */
> +	idx = device_property_match_string(dev, "io-channel-names", "pressure");
> +	if (idx >= 0) {
> +		if (idx >= ARRAY_SIZE(st->ch))
> +			return -EOVERFLOW;
> +
> +		st->ch[idx] = GRTS_CH_PRESSURE;
> +		st->pressure = true;
> +
> +		return 0;
> +	}
> +
> +	/* if no pressure is defined, try optional z1 + z2 */
> +	idx = device_property_match_string(dev, "io-channel-names", "z1");
> +	if (idx < 0)
> +		return 0;
> +
> +	if (idx >= ARRAY_SIZE(st->ch))
> +		return -EOVERFLOW;
> +
> +	st->ch[idx] = GRTS_CH_Z1;
> +
> +	/* if z1 is provided z2 is not optional */
> +	idx = device_property_match_string(dev, "io-channel-names", "z2");
> +	if (idx < 0)
> +		return idx;
> +
> +	if (idx >= ARRAY_SIZE(st->ch))
> +		return -EOVERFLOW;
> +
> +	st->ch[idx] = GRTS_CH_Z2;
> +	st->pressure = true;
> +
> +	error = device_property_read_u32(dev,
> +					 "touchscreen-x-plate-ohms",
> +					 &st->x_plate_ohms);
> +	if (error) {
> +		dev_err(dev, "can't get touchscreen-x-plate-ohms property\n");
> +		return error;
> +	}
> +
> +	return 0;
> +}
> +
>  static int grts_probe(struct platform_device *pdev)
>  {
>  	struct grts_state *st;
>  	struct input_dev *input;
>  	struct device *dev = &pdev->dev;
> -	struct iio_channel *chan;
>  	int error;
>  
>  	st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL);
> @@ -115,12 +228,13 @@ static int grts_probe(struct platform_device *pdev)
>  		return error;
>  	}
>  
> -	chan = &st->iio_chans[0];
> -	st->pressure = false;
> -	while (chan && chan->indio_dev) {
> -		if (!strcmp(chan->channel->datasheet_name, "pressure"))
> -			st->pressure = true;
> -		chan++;
> +	if (!device_property_present(dev, "io-channel-names"))
> +		return -ENODEV;
> +
> +	error = grts_get_properties(st, dev);
> +	if (error) {
> +		dev_err(dev, "Failed to parse properties\n");
> +		return error;
>  	}
>  
>  	if (st->pressure) {
> @@ -148,7 +262,7 @@ static int grts_probe(struct platform_device *pdev)
>  	input_set_abs_params(input, ABS_Y, 0, GRTS_MAX_POS_MASK - 1, 0, 0);
>  	if (st->pressure)
>  		input_set_abs_params(input, ABS_PRESSURE, st->pressure_min,
> -				     0xffff, 0, 0);
> +				     GRTS_DEFAULT_PRESSURE_MAX, 0, 0);
>  
>  	input_set_capability(input, EV_KEY, BTN_TOUCH);
>