* [PATCH v2 1/4] dt-bindings: touchscreen: Convert resistive-adc-touch binding to json schema
2021-05-18 12:57 [PATCH v2 0/4] add z1 and z2 channels support for resistive-adc-touch driver Oleksij Rempel
@ 2021-05-18 12:57 ` Oleksij Rempel
2021-05-18 12:57 ` [PATCH v2 2/4] dt-bindings: touchscreen: add touchscreen-x/y-plate-ohms property Oleksij Rempel
` (2 subsequent siblings)
3 siblings, 0 replies; 6+ messages in thread
From: Oleksij Rempel @ 2021-05-18 12:57 UTC (permalink / raw)
To: Dmitry Torokhov, Rob Herring, Jonathan Cameron
Cc: Oleksij Rempel, kernel, linux-kernel, linux-input, David Jander,
devicetree
Convert the resistive-adc-touch binding to DT schema format using json-schema.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
.../input/touchscreen/resistive-adc-touch.txt | 33 ----------
.../touchscreen/resistive-adc-touch.yaml | 61 +++++++++++++++++++
2 files changed, 61 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..53df21a6589e
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml
@@ -0,0 +1,61 @@
+# 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
+ maxItems: 3
+ items:
+ - description: x
+ - description: y
+ - description: pressure (optional)
+
+ io-channel-names:
+ items:
+ - const: x
+ - const: y
+ - const: 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:
+ - |
+ resistive_touch {
+ compatible = "resistive-adc-touch";
+ touchscreen-min-pressure = <50000>;
+ io-channels = <&adc 24>, <&adc 25>, <&adc 26>;
+ io-channel-names = "x", "y", "pressure";
+ };
--
2.29.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH v2 3/4] dt-bindings: touchscreen: resistive-adc-touch: add support for z1 and z2 channels
2021-05-18 12:57 [PATCH v2 0/4] add z1 and z2 channels support for resistive-adc-touch driver Oleksij Rempel
2021-05-18 12:57 ` [PATCH v2 1/4] dt-bindings: touchscreen: Convert resistive-adc-touch binding to json schema Oleksij Rempel
2021-05-18 12:57 ` [PATCH v2 2/4] dt-bindings: touchscreen: add touchscreen-x/y-plate-ohms property Oleksij Rempel
@ 2021-05-18 12:57 ` Oleksij Rempel
2021-05-18 18:15 ` Rob Herring
2021-05-18 12:57 ` [PATCH v2 4/4] Input: " Oleksij Rempel
3 siblings, 1 reply; 6+ messages in thread
From: Oleksij Rempel @ 2021-05-18 12:57 UTC (permalink / raw)
To: Dmitry Torokhov, Rob Herring, Jonathan Cameron
Cc: Oleksij Rempel, kernel, linux-kernel, linux-input, David Jander,
devicetree
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>
---
.../bindings/input/touchscreen/resistive-adc-touch.yaml | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml b/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml
index 53df21a6589e..538c3b1ef1e1 100644
--- a/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml
+++ b/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml
@@ -43,6 +43,7 @@ properties:
touchscreen-inverted-y: true
touchscreen-swapped-x-y: true
touchscreen-min-pressure: true
+ touchscreen-x-plate-ohms: true
additionalProperties: false
@@ -59,3 +60,11 @@ examples:
io-channels = <&adc 24>, <&adc 25>, <&adc 26>;
io-channel-names = "x", "y", "pressure";
};
+ - |
+ resistive_touch {
+ compatible = "resistive-adc-touch";
+ touchscreen-min-pressure = <50000>;
+ io-channels = <&adc 1>, <&adc 2>, <&adc 3>, <&adc 4>;
+ io-channel-names = "x", "y", "z1", "z2";
+ touchscreen-x-plate-ohms = <800>;
+ };
--
2.29.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH v2 4/4] Input: resistive-adc-touch: add support for z1 and z2 channels
2021-05-18 12:57 [PATCH v2 0/4] add z1 and z2 channels support for resistive-adc-touch driver Oleksij Rempel
` (2 preceding siblings ...)
2021-05-18 12:57 ` [PATCH v2 3/4] dt-bindings: touchscreen: resistive-adc-touch: add support for z1 and z2 channels Oleksij Rempel
@ 2021-05-18 12:57 ` Oleksij Rempel
3 siblings, 0 replies; 6+ messages in thread
From: Oleksij Rempel @ 2021-05-18 12:57 UTC (permalink / raw)
To: Dmitry Torokhov, Rob Herring, Jonathan Cameron
Cc: Oleksij Rempel, kernel, linux-kernel, linux-input, David Jander,
devicetree
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 | 141 ++++++++++++++++--
1 file changed, 128 insertions(+), 13 deletions(-)
diff --git a/drivers/input/touchscreen/resistive-adc-touch.c b/drivers/input/touchscreen/resistive-adc-touch.c
index e50af30183f4..470b95ed3569 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 */
@@ -94,6 +142,72 @@ 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;
@@ -115,12 +229,13 @@ 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 +263,7 @@ 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
^ permalink raw reply related [flat|nested] 6+ messages in thread