[PATCH v5 0/3] Add support for touchscreen on Colibri VF50

[PATCH v5 0/3] Add support for touchscreen on Colibri VF50

[Sanchayan Maity]

Hello,

The patchset adds support for 4 wire touchscreen on Toradex Colibri
VF50 modules.

Thanks Dmitry and Stefan for your feedback.

Changes since v4:
1. Add missing header file for gpio consumer.
2. Purge unneeded gpio descriptor entry in struct
3. Do not cast from void * pointer in IRQ bh
4. Make sure to have the gpio ym inactive and pinmux in ADC state
on close
5. Return error codes directly instead of assigning and returning
6. Fix leaking of IIO channels and install devm action earlier
7. Make sure that correct number of ADC channels are specified
8. Improve DT documentation
9. Also include DT pressure property in our evaluation board dts file

Changes since v3:
1. Add a #define for the average readings measurement.
2. Instead of configuring gpios every open, configure them on request.
3. Use a memory barrier and synchronize irq call to make sure IRQ is
not running past close.
4. Drop inline for vf50_ts_get_gpiod
5. Convert "ret" to "error"
6. Use devm_add_action to add a function for releasing iio channels and
drop remove completely.
7. Kill __set_bits()
8. Instead of requesting for pen irq as gpio and then irq, use the
interrupts property for DT and let it be handled automatically. Anyways
we never read it's state.
9. Just use IRQF_ONESHOT here, rely on the platform/OF to read and set up
the trigger properly (via "interrupts" property).

Changes since v2:
1. Fix pin multiplexing for pins in idle state. Configuration of the
pen detect pull up viz. PTA19__GPIO_9 resulted in generation of pen
irq's on a continuous basis.
2. Fix pinmux of the ADC pins as per the recommended pinmux in TRM.
3. Use a threaded irq handler instead of a irq handler plus workqueue
approach.
4. Use a low level trigger with oneshot flag specifier instead of the
previous falling edge triggered irq's. This coupled with the fix in
point 1 fixes the previous continuous spurious irq generation bug.
5. Change/fix the TS measurement logic to account for the fact that
iio_channel_read_raw might actually return an error. To be more
specific use break instead of continue and take care to close the
FET's in case of channel read error.
6. Drop the first patch "Add io-channel-cells property for ADC node"
as it has already been applied.
7. Move the iio channel get call again at the start. Having it in
the end resulted in crashes sometimes when iio was not probed and
the ts device got probed and opened earlier.

Changes since v1:
1. Fix/drop comments
2. Use an inline function for multiple gpiod_get calls in probe
3. Remove the pull up in the pinmux specified in DT for touchctrl_gpios
4. Add the io-channel-cells property before status property.
5. Add GPIOLIB as dependency in the Kconfig file

Version 4 of the patchset can be found here
https://lkml.org/lkml/2015/8/21/339

Version 3 of the patchset can be found here
https://lkml.org/lkml/2015/8/5/173

Version 2 of the patchset can be found here
https://www.mail-archive.com/linux-input@vger.kernel.org/msg18090.html

Version 1 of the patchset can be found here
https://lkml.org/lkml/2015/6/30/103

Regards,
Sanchayan.

Sanchayan Maity (3):
  ARM: dts: vf500-colibri: Add device tree node for touchscreen support
  input: Add DT binding documentation for Colibri VF50 touchscreen
  touchscreen: colibri-vf50-ts: Add touchscreen support for Colibri VF50

 .../bindings/input/touchscreen/colibri-vf50-ts.txt |  36 ++
 arch/arm/boot/dts/vf500-colibri-eval-v3.dts        |   5 +
 arch/arm/boot/dts/vf500-colibri.dtsi               |  47 +++
 drivers/input/touchscreen/Kconfig                  |  12 +
 drivers/input/touchscreen/Makefile                 |   1 +
 drivers/input/touchscreen/colibri-vf50-ts.c        | 381 +++++++++++++++++++++
 6 files changed, 482 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/colibri-vf50-ts.txt
 create mode 100644 drivers/input/touchscreen/colibri-vf50-ts.c

-- 
2.5.0

[PATCH v5 1/3] ARM: dts: vf500-colibri: Add device tree node for touchscreen support

[Sanchayan Maity]

Add device tree node for touchscreen support on Colibri VF50. The
touchscreen functionality on VF50 uses the ADC channels of Vybrid
and some GPIOs. Also add pinctrl nodes for proper pinmux.

Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
---
 arch/arm/boot/dts/vf500-colibri-eval-v3.dts |  5 +++
 arch/arm/boot/dts/vf500-colibri.dtsi        | 47 +++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/arch/arm/boot/dts/vf500-colibri-eval-v3.dts b/arch/arm/boot/dts/vf500-colibri-eval-v3.dts
index 7fc782c..c3173fc 100644
--- a/arch/arm/boot/dts/vf500-colibri-eval-v3.dts
+++ b/arch/arm/boot/dts/vf500-colibri-eval-v3.dts
@@ -15,3 +15,8 @@
 	model = "Toradex Colibri VF50 on Colibri Evaluation Board";
 	compatible = "toradex,vf500-colibri_vf50-on-eval", "toradex,vf500-colibri_vf50", "fsl,vf500";
 };
+
+&touchscreen {
+	vf50-ts-min-pressure = <200>;
+	status = "okay";
+};
diff --git a/arch/arm/boot/dts/vf500-colibri.dtsi b/arch/arm/boot/dts/vf500-colibri.dtsi
index cee34a3..84f091d 100644
--- a/arch/arm/boot/dts/vf500-colibri.dtsi
+++ b/arch/arm/boot/dts/vf500-colibri.dtsi
@@ -17,4 +17,51 @@
 	memory {
 		reg = <0x80000000 0x8000000>;
 	};
+
+	touchscreen: vf50-touchscreen {
+		compatible = "toradex,vf50-touchscreen";
+		io-channels = <&adc1 0>,<&adc0 0>,
+				<&adc0 1>,<&adc1 2>;
+		xp-gpios = <&gpio0 13 GPIO_ACTIVE_LOW>;
+		xm-gpios = <&gpio2 29 GPIO_ACTIVE_HIGH>;
+		yp-gpios = <&gpio0 12 GPIO_ACTIVE_LOW>;
+		ym-gpios = <&gpio0 4 GPIO_ACTIVE_HIGH>;
+		interrupt-parent = <&gpio0>;
+		interrupts = <8 IRQ_TYPE_LEVEL_LOW>;
+		pinctrl-names = "idle","default","gpios";
+		pinctrl-0 = <&pinctrl_touchctrl_idle>;
+		pinctrl-1 = <&pinctrl_touchctrl_default>;
+		pinctrl-2 = <&pinctrl_touchctrl_gpios>;
+		vf50-ts-min-pressure = <200>;
+		status = "disabled";
+	};
+};
+
+&iomuxc {
+	vf610-colibri {
+		pinctrl_touchctrl_idle: touchctrl_idle {
+			fsl,pins = <
+				VF610_PAD_PTA18__GPIO_8		0x006d
+				VF610_PAD_PTA19__GPIO_9		0x006c
+				>;
+		};
+
+		pinctrl_touchctrl_default: touchctrl_default {
+			fsl,pins = <
+				VF610_PAD_PTA18__ADC0_SE0	0x0040
+				VF610_PAD_PTA19__ADC0_SE1	0x0040
+				VF610_PAD_PTA16__ADC1_SE0	0x0040
+				VF610_PAD_PTB2__ADC1_SE2	0x0040
+				>;
+		};
+
+		pinctrl_touchctrl_gpios: touchctrl_gpios {
+			fsl,pins = <
+				VF610_PAD_PTA23__GPIO_13	0x22e9
+				VF610_PAD_PTB23__GPIO_93	0x22e9
+				VF610_PAD_PTA22__GPIO_12	0x22e9
+				VF610_PAD_PTA11__GPIO_4		0x22e9
+				>;
+		};
+	};
 };
-- 
2.5.0

[PATCH v5 2/3] input: Add DT binding documentation for Colibri VF50 touchscreen

[Sanchayan Maity]

This adds device tree binding documentation for the Colibri VF50
touchscreen driver.

Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
---
 .../bindings/input/touchscreen/colibri-vf50-ts.txt | 36 ++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/colibri-vf50-ts.txt

diff --git a/Documentation/devicetree/bindings/input/touchscreen/colibri-vf50-ts.txt b/Documentation/devicetree/bindings/input/touchscreen/colibri-vf50-ts.txt
new file mode 100644
index 0000000..9d9e930
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/touchscreen/colibri-vf50-ts.txt
@@ -0,0 +1,36 @@
+* Toradex Colibri VF50 Touchscreen driver
+
+Required Properties:
+- compatible must be toradex,vf50-touchscreen
+- io-channels: adc channels being used by the Colibri VF50 module
+- xp-gpios: FET gate driver for input of X+
+- xm-gpios: FET gate driver for input of X-
+- yp-gpios: FET gate driver for input of Y+
+- ym-gpios: FET gate driver for input of Y-
+- interrupt-parent: phandle for the interrupt controller
+- interrupts: pen irq interrupt for touch detection
+- pinctrl-names: "idle", "default", "gpios"
+- pinctrl-0: pinctrl node for pen/touch detection state pinmux
+- pinctrl-1: pinctrl node for X/Y and pressure measurement (ADC) state pinmux
+- pinctrl-2: pinctrl node for gpios functioning as FET gate drivers
+- vf50-ts-min-pressure: pressure level at which to stop measuring X/Y values
+
+Example:
+
+	touchctrl: vf50_touchctrl {
+		compatible = "toradex,vf50-touchscreen";
+		io-channels = <&adc1 0>,<&adc0 0>,
+				<&adc0 1>,<&adc1 2>;
+		xp-gpios = <&gpio0 13 GPIO_ACTIVE_LOW>;
+		xm-gpios = <&gpio2 29 GPIO_ACTIVE_HIGH>;
+		yp-gpios = <&gpio0 12 GPIO_ACTIVE_LOW>;
+		ym-gpios = <&gpio0 4 GPIO_ACTIVE_HIGH>;
+		interrupt-parent = <&gpio0>;
+		interrupts = <8 IRQ_TYPE_LEVEL_LOW>;
+		pinctrl-names = "idle","default","gpios";
+		pinctrl-0 = <&pinctrl_touchctrl_idle>;
+		pinctrl-1 = <&pinctrl_touchctrl_default>;
+		pinctrl-2 = <&pinctrl_touchctrl_gpios>;
+		vf50-ts-min-pressure = <200>;
+		status = "disabled";
+	};
-- 
2.5.0

[PATCH v5 3/3] touchscreen: colibri-vf50-ts: Add touchscreen support for Colibri VF50

[Sanchayan Maity]

The Colibri Vybrid VF50 module supports 4-wire touchscreens using
FETs and ADC inputs. This driver uses the IIO consumer interface
and relies on the vf610_adc driver based on the IIO framework.

Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
---
 drivers/input/touchscreen/Kconfig           |  12 +
 drivers/input/touchscreen/Makefile          |   1 +
 drivers/input/touchscreen/colibri-vf50-ts.c | 381 ++++++++++++++++++++++++++++
 3 files changed, 394 insertions(+)
 create mode 100644 drivers/input/touchscreen/colibri-vf50-ts.c

diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index 80f6386..28948ca 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -1027,4 +1027,16 @@ config TOUCHSCREEN_ZFORCE
 	  To compile this driver as a module, choose M here: the
 	  module will be called zforce_ts.
 
+config TOUCHSCREEN_COLIBRI_VF50
+	tristate "Toradex Colibri on board touchscreen driver"
+	depends on GPIOLIB && IIO && VF610_ADC
+	help
+	  Say Y here if you have a Colibri VF50 and plan to use
+	  the on-board provided 4-wire touchscreen driver.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called colibri_vf50_ts.
+
 endif
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 44deea7..93746a0 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -84,3 +84,4 @@ obj-$(CONFIG_TOUCHSCREEN_W90X900)	+= w90p910_ts.o
 obj-$(CONFIG_TOUCHSCREEN_SX8654)	+= sx8654.o
 obj-$(CONFIG_TOUCHSCREEN_TPS6507X)	+= tps6507x-ts.o
 obj-$(CONFIG_TOUCHSCREEN_ZFORCE)	+= zforce_ts.o
+obj-$(CONFIG_TOUCHSCREEN_COLIBRI_VF50)	+= colibri-vf50-ts.o
diff --git a/drivers/input/touchscreen/colibri-vf50-ts.c b/drivers/input/touchscreen/colibri-vf50-ts.c
new file mode 100644
index 0000000..26187e0
--- /dev/null
+++ b/drivers/input/touchscreen/colibri-vf50-ts.c
@@ -0,0 +1,381 @@
+/* Copyright 2015 Toradex AG
+ *
+ * Toradex Colibri VF50 Touchscreen driver
+ *
+ * Originally authored by Stefan Agner for 3.0 kernel
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
+#include <linux/iio/consumer.h>
+#include <linux/iio/types.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#define DRIVER_NAME "colibri-vf50-ts"
+#define DRV_VERSION "1.0"
+
+#define VF_ADC_MAX ((1 << 12) - 1)
+
+#define COLI_TOUCH_MIN_DELAY_US 1000
+#define COLI_TOUCH_MAX_DELAY_US 2000
+#define COLI_TOUCH_NO_OF_AVGS	5
+#define COLI_TOUCH_REQ_ADC_CHAN	4
+
+struct vf50_touch_device {
+	struct platform_device	*pdev;
+	struct input_dev	*ts_input;
+	struct iio_channel	*channels;
+	struct gpio_desc *gpio_xp;
+	struct gpio_desc *gpio_xm;
+	struct gpio_desc *gpio_yp;
+	struct gpio_desc *gpio_ym;
+	int pen_irq;
+	int min_pressure;
+	bool stop_touchscreen;
+};
+
+/*
+ * Enables given plates and measures touch parameters using ADC
+ */
+static int adc_ts_measure(struct iio_channel *channel,
+		  struct gpio_desc *plate_p, struct gpio_desc *plate_m)
+{
+	int i, value = 0, val = 0;
+	int ret;
+
+	gpiod_set_value(plate_p, 1);
+	gpiod_set_value(plate_m, 1);
+
+	usleep_range(COLI_TOUCH_MIN_DELAY_US, COLI_TOUCH_MAX_DELAY_US);
+
+	for (i = 0; i < COLI_TOUCH_NO_OF_AVGS; i++) {
+		ret = iio_read_channel_raw(channel, &val);
+		if (ret < 0) {
+			value = ret;
+			goto error_iio_read;
+		}
+
+		value += val;
+	}
+
+	value /= COLI_TOUCH_NO_OF_AVGS;
+
+error_iio_read:
+	gpiod_set_value(plate_p, 0);
+	gpiod_set_value(plate_m, 0);
+
+	return value;
+}
+
+/*
+ * Enable touch detection using falling edge detection on XM
+ */
+static void vf50_ts_enable_touch_detection(struct vf50_touch_device *vf50_ts)
+{
+	/* Enable plate YM (needs to be strong GND, high active) */
+	gpiod_set_value(vf50_ts->gpio_ym, 1);
+
+	/*
+	 * Let the platform mux to idle state in order to enable
+	 * Pull-Up on GPIO
+	 */
+	pinctrl_pm_select_idle_state(&vf50_ts->pdev->dev);
+}
+
+/*
+ * ADC touch screen sampling bottom half irq handler
+ */
+static irqreturn_t vf50_ts_irq_bh(int irq, void *private)
+{
+	struct vf50_touch_device *vf50_ts = private;
+	struct device *dev = &vf50_ts->pdev->dev;
+	int val_x, val_y, val_z1, val_z2, val_p = 0;
+	bool discard_val_on_start = true;
+
+	/* Disable the touch detection plates */
+	gpiod_set_value(vf50_ts->gpio_ym, 0);
+
+	/* Let the platform mux to default state in order to mux as ADC */
+	pinctrl_pm_select_default_state(dev);
+
+	while (!vf50_ts->stop_touchscreen) {
+		/* X-Direction */
+		val_x = adc_ts_measure(&vf50_ts->channels[0],
+				vf50_ts->gpio_xp, vf50_ts->gpio_xm);
+		if (val_x < 0)
+			break;
+
+		/* Y-Direction */
+		val_y = adc_ts_measure(&vf50_ts->channels[1],
+				vf50_ts->gpio_yp, vf50_ts->gpio_ym);
+		if (val_y < 0)
+			break;
+
+		/*
+		 * Touch pressure
+		 * Measure on XP/YM
+		 */
+		val_z1 = adc_ts_measure(&vf50_ts->channels[2],
+				vf50_ts->gpio_yp, vf50_ts->gpio_xm);
+		if (val_z1 < 0)
+			break;
+		val_z2 = adc_ts_measure(&vf50_ts->channels[3],
+				vf50_ts->gpio_yp, vf50_ts->gpio_xm);
+		if (val_z2 < 0)
+			break;
+
+		/* Validate signal (avoid calculation using noise) */
+		if (val_z1 > 64 && val_x > 64) {
+			/*
+			 * Calculate resistance between the plates
+			 * lower resistance means higher pressure
+			 */
+			int r_x = (1000 * val_x) / VF_ADC_MAX;
+
+			val_p = (r_x * val_z2) / val_z1 - r_x;
+
+		} else {
+			val_p = 2000;
+		}
+
+		val_p = 2000 - val_p;
+		dev_dbg(dev, "Measured values: x: %d, y: %d, z1: %d, z2: %d, "
+			"p: %d\n", val_x, val_y, val_z1, val_z2, val_p);
+
+		/*
+		 * If touch pressure is too low, stop measuring and reenable
+		 * touch detection
+		 */
+		if (val_p < vf50_ts->min_pressure || val_p > 2000)
+			break;
+
+		/*
+		 * The pressure may not be enough for the first x and the
+		 * second y measurement, but, the pressure is ok when the
+		 * driver is doing the third and fourth measurement. To
+		 * take care of this, we drop the first measurement always.
+		 */
+		if (discard_val_on_start) {
+			discard_val_on_start = false;
+		} else {
+			/*
+			 * Report touch position and sleep for
+			 * next measurement
+			 */
+			input_report_abs(vf50_ts->ts_input,
+					ABS_X, VF_ADC_MAX - val_x);
+			input_report_abs(vf50_ts->ts_input,
+					ABS_Y, VF_ADC_MAX - val_y);
+			input_report_abs(vf50_ts->ts_input,
+					ABS_PRESSURE, val_p);
+			input_report_key(vf50_ts->ts_input, BTN_TOUCH, 1);
+			input_sync(vf50_ts->ts_input);
+		}
+
+		msleep(10);
+	}
+
+	/* Report no more touch, reenable touch detection */
+	input_report_abs(vf50_ts->ts_input, ABS_PRESSURE, 0);
+	input_report_key(vf50_ts->ts_input, BTN_TOUCH, 0);
+	input_sync(vf50_ts->ts_input);
+
+	vf50_ts_enable_touch_detection(vf50_ts);
+
+	/* Wait for the pull-up to be stable on high */
+	msleep(10);
+
+	return IRQ_HANDLED;
+}
+
+static int vf50_ts_open(struct input_dev *dev_input)
+{
+	struct vf50_touch_device *touchdev = input_get_drvdata(dev_input);
+	struct device *dev = &touchdev->pdev->dev;
+
+	dev_dbg(dev, "Input device %s opened, starting touch detection\n",
+			dev_input->name);
+
+	touchdev->stop_touchscreen = false;
+
+	/* Mux detection before request IRQ, wait for pull-up to settle */
+	vf50_ts_enable_touch_detection(touchdev);
+	msleep(10);
+
+	return 0;
+}
+
+static void vf50_ts_close(struct input_dev *dev_input)
+{
+	struct vf50_touch_device *touchdev = input_get_drvdata(dev_input);
+	struct device *dev = &touchdev->pdev->dev;
+
+	touchdev->stop_touchscreen = true;
+
+	/* Make sure IRQ is not running past close */
+	mb();
+	synchronize_irq(touchdev->pen_irq);
+
+	gpiod_set_value(touchdev->gpio_ym, 0);
+	pinctrl_pm_select_default_state(dev);
+
+	dev_dbg(dev, "Input device %s closed, disable touch detection\n",
+		dev_input->name);
+}
+
+static int vf50_ts_get_gpiod(struct device *dev,
+	struct gpio_desc **gpio_d, const char *con_id, enum gpiod_flags flags)
+{
+	int error;
+
+	*gpio_d = devm_gpiod_get(dev, con_id, flags);
+	if (IS_ERR(*gpio_d)) {
+		error = PTR_ERR(*gpio_d);
+		dev_err(dev, "Could not get gpio_%s %d\n", con_id, error);
+		return error;
+	}
+
+	return 0;
+}
+
+static void vf50_ts_channel_release(void *data)
+{
+	struct iio_channel *channels = data;
+
+	iio_channel_release_all(channels);
+}
+
+static int vf50_ts_probe(struct platform_device *pdev)
+{
+	struct input_dev *input;
+	struct iio_channel *channels;
+	struct device *dev = &pdev->dev;
+	struct vf50_touch_device *touchdev;
+	int num_adc_channels = 0;
+	int error;
+
+	channels = iio_channel_get_all(dev);
+	if (IS_ERR(channels))
+		return PTR_ERR(channels);
+
+	error = devm_add_action(dev, vf50_ts_channel_release, channels);
+	if (error) {
+		iio_channel_release_all(channels);
+		dev_err(dev, "Failed to register iio channel release action");
+		return error;
+	}
+
+	touchdev = devm_kzalloc(dev, sizeof(*touchdev), GFP_KERNEL);
+	if (!touchdev)
+		return -ENOMEM;
+
+	touchdev->pdev = pdev;
+	touchdev->channels = channels;
+
+	while (channels[num_adc_channels].indio_dev)
+		num_adc_channels++;
+
+	if (num_adc_channels != COLI_TOUCH_REQ_ADC_CHAN) {
+		dev_err(dev, "Inadequate ADC channels specified\n");
+		return -EINVAL;
+	}
+
+	error = of_property_read_u32(dev->of_node, "vf50-ts-min-pressure",
+				 &touchdev->min_pressure);
+	if (error)
+		return error;
+
+	input = devm_input_allocate_device(dev);
+	if (!input) {
+		dev_err(dev, "Failed to allocate TS input device\n");
+		return -ENOMEM;
+	}
+
+	platform_set_drvdata(pdev, touchdev);
+
+	input->name = DRIVER_NAME;
+	input->id.bustype = BUS_HOST;
+	input->dev.parent = dev;
+	input->open = vf50_ts_open;
+	input->close = vf50_ts_close;
+
+	input_set_capability(input, EV_KEY, BTN_TOUCH);
+	input_set_abs_params(input, ABS_X, 0, VF_ADC_MAX, 0, 0);
+	input_set_abs_params(input, ABS_Y, 0, VF_ADC_MAX, 0, 0);
+	input_set_abs_params(input, ABS_PRESSURE, 0, VF_ADC_MAX, 0, 0);
+
+	touchdev->ts_input = input;
+	input_set_drvdata(input, touchdev);
+	error = input_register_device(input);
+	if (error) {
+		dev_err(dev, "Failed to register input device\n");
+		return error;
+	}
+
+	error = vf50_ts_get_gpiod(dev, &touchdev->gpio_xp,
+				"xp", GPIOD_OUT_LOW);
+	if (error)
+		return error;
+
+	error = vf50_ts_get_gpiod(dev, &touchdev->gpio_xm,
+				"xm", GPIOD_OUT_LOW);
+	if (error)
+		return error;
+
+	error = vf50_ts_get_gpiod(dev, &touchdev->gpio_yp,
+				"yp", GPIOD_OUT_LOW);
+	if (error)
+		return error;
+
+	error = vf50_ts_get_gpiod(dev, &touchdev->gpio_ym,
+				"ym", GPIOD_OUT_LOW);
+	if (error)
+		return error;
+
+	touchdev->pen_irq = platform_get_irq(pdev, 0);
+	if (touchdev->pen_irq < 0)
+		return touchdev->pen_irq;
+
+	error = devm_request_threaded_irq(dev, touchdev->pen_irq, NULL,
+			vf50_ts_irq_bh, IRQF_ONESHOT,
+			"vf50 touch", touchdev);
+	if (error < 0)
+		return error;
+
+	return 0;
+}
+
+static const struct of_device_id vf50_touch_of_match[] = {
+	{ .compatible = "toradex,vf50-touchscreen", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, vf50_touch_of_match);
+
+static struct platform_driver vf50_touch_driver = {
+	.driver = {
+		.name = "toradex,vf50_touchctrl",
+		.of_match_table = vf50_touch_of_match,
+	},
+	.probe = vf50_ts_probe,
+};
+
+module_platform_driver(vf50_touch_driver);
+
+MODULE_AUTHOR("Sanchayan Maity");
+MODULE_DESCRIPTION("Colibri VF50 Touchscreen driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);
-- 
2.5.0

Re: [PATCH v5 3/3] touchscreen: colibri-vf50-ts: Add touchscreen support for Colibri VF50

[Dmitry Torokhov]

On Tue, Sep 01, 2015 at 06:06:55PM +0530, Sanchayan Maity wrote:
> The Colibri Vybrid VF50 module supports 4-wire touchscreens using
> FETs and ADC inputs. This driver uses the IIO consumer interface
> and relies on the vf610_adc driver based on the IIO framework.
> 
> Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>

Merged #2 and #3 and applied, thank you.

> ---
>  drivers/input/touchscreen/Kconfig           |  12 +
>  drivers/input/touchscreen/Makefile          |   1 +
>  drivers/input/touchscreen/colibri-vf50-ts.c | 381 ++++++++++++++++++++++++++++
>  3 files changed, 394 insertions(+)
>  create mode 100644 drivers/input/touchscreen/colibri-vf50-ts.c
> 
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index 80f6386..28948ca 100644
> --- a/drivers/input/touchscreen/Kconfig
> +++ b/drivers/input/touchscreen/Kconfig
> @@ -1027,4 +1027,16 @@ config TOUCHSCREEN_ZFORCE
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called zforce_ts.
>  
> +config TOUCHSCREEN_COLIBRI_VF50
> +	tristate "Toradex Colibri on board touchscreen driver"
> +	depends on GPIOLIB && IIO && VF610_ADC
> +	help
> +	  Say Y here if you have a Colibri VF50 and plan to use
> +	  the on-board provided 4-wire touchscreen driver.
> +
> +	  If unsure, say N.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called colibri_vf50_ts.
> +
>  endif
> diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
> index 44deea7..93746a0 100644
> --- a/drivers/input/touchscreen/Makefile
> +++ b/drivers/input/touchscreen/Makefile
> @@ -84,3 +84,4 @@ obj-$(CONFIG_TOUCHSCREEN_W90X900)	+= w90p910_ts.o
>  obj-$(CONFIG_TOUCHSCREEN_SX8654)	+= sx8654.o
>  obj-$(CONFIG_TOUCHSCREEN_TPS6507X)	+= tps6507x-ts.o
>  obj-$(CONFIG_TOUCHSCREEN_ZFORCE)	+= zforce_ts.o
> +obj-$(CONFIG_TOUCHSCREEN_COLIBRI_VF50)	+= colibri-vf50-ts.o
> diff --git a/drivers/input/touchscreen/colibri-vf50-ts.c b/drivers/input/touchscreen/colibri-vf50-ts.c
> new file mode 100644
> index 0000000..26187e0
> --- /dev/null
> +++ b/drivers/input/touchscreen/colibri-vf50-ts.c
> @@ -0,0 +1,381 @@
> +/* Copyright 2015 Toradex AG
> + *
> + * Toradex Colibri VF50 Touchscreen driver
> + *
> + * Originally authored by Stefan Agner for 3.0 kernel
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/gpio.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/iio/consumer.h>
> +#include <linux/iio/types.h>
> +#include <linux/input.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/pinctrl/consumer.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +
> +#define DRIVER_NAME "colibri-vf50-ts"
> +#define DRV_VERSION "1.0"
> +
> +#define VF_ADC_MAX ((1 << 12) - 1)
> +
> +#define COLI_TOUCH_MIN_DELAY_US 1000
> +#define COLI_TOUCH_MAX_DELAY_US 2000
> +#define COLI_TOUCH_NO_OF_AVGS	5
> +#define COLI_TOUCH_REQ_ADC_CHAN	4
> +
> +struct vf50_touch_device {
> +	struct platform_device	*pdev;
> +	struct input_dev	*ts_input;
> +	struct iio_channel	*channels;
> +	struct gpio_desc *gpio_xp;
> +	struct gpio_desc *gpio_xm;
> +	struct gpio_desc *gpio_yp;
> +	struct gpio_desc *gpio_ym;
> +	int pen_irq;
> +	int min_pressure;
> +	bool stop_touchscreen;
> +};
> +
> +/*
> + * Enables given plates and measures touch parameters using ADC
> + */
> +static int adc_ts_measure(struct iio_channel *channel,
> +		  struct gpio_desc *plate_p, struct gpio_desc *plate_m)
> +{
> +	int i, value = 0, val = 0;
> +	int ret;
> +
> +	gpiod_set_value(plate_p, 1);
> +	gpiod_set_value(plate_m, 1);
> +
> +	usleep_range(COLI_TOUCH_MIN_DELAY_US, COLI_TOUCH_MAX_DELAY_US);
> +
> +	for (i = 0; i < COLI_TOUCH_NO_OF_AVGS; i++) {
> +		ret = iio_read_channel_raw(channel, &val);
> +		if (ret < 0) {
> +			value = ret;
> +			goto error_iio_read;
> +		}
> +
> +		value += val;
> +	}
> +
> +	value /= COLI_TOUCH_NO_OF_AVGS;
> +
> +error_iio_read:
> +	gpiod_set_value(plate_p, 0);
> +	gpiod_set_value(plate_m, 0);
> +
> +	return value;
> +}
> +
> +/*
> + * Enable touch detection using falling edge detection on XM
> + */
> +static void vf50_ts_enable_touch_detection(struct vf50_touch_device *vf50_ts)
> +{
> +	/* Enable plate YM (needs to be strong GND, high active) */
> +	gpiod_set_value(vf50_ts->gpio_ym, 1);
> +
> +	/*
> +	 * Let the platform mux to idle state in order to enable
> +	 * Pull-Up on GPIO
> +	 */
> +	pinctrl_pm_select_idle_state(&vf50_ts->pdev->dev);
> +}
> +
> +/*
> + * ADC touch screen sampling bottom half irq handler
> + */
> +static irqreturn_t vf50_ts_irq_bh(int irq, void *private)
> +{
> +	struct vf50_touch_device *vf50_ts = private;
> +	struct device *dev = &vf50_ts->pdev->dev;
> +	int val_x, val_y, val_z1, val_z2, val_p = 0;
> +	bool discard_val_on_start = true;
> +
> +	/* Disable the touch detection plates */
> +	gpiod_set_value(vf50_ts->gpio_ym, 0);
> +
> +	/* Let the platform mux to default state in order to mux as ADC */
> +	pinctrl_pm_select_default_state(dev);
> +
> +	while (!vf50_ts->stop_touchscreen) {
> +		/* X-Direction */
> +		val_x = adc_ts_measure(&vf50_ts->channels[0],
> +				vf50_ts->gpio_xp, vf50_ts->gpio_xm);
> +		if (val_x < 0)
> +			break;
> +
> +		/* Y-Direction */
> +		val_y = adc_ts_measure(&vf50_ts->channels[1],
> +				vf50_ts->gpio_yp, vf50_ts->gpio_ym);
> +		if (val_y < 0)
> +			break;
> +
> +		/*
> +		 * Touch pressure
> +		 * Measure on XP/YM
> +		 */
> +		val_z1 = adc_ts_measure(&vf50_ts->channels[2],
> +				vf50_ts->gpio_yp, vf50_ts->gpio_xm);
> +		if (val_z1 < 0)
> +			break;
> +		val_z2 = adc_ts_measure(&vf50_ts->channels[3],
> +				vf50_ts->gpio_yp, vf50_ts->gpio_xm);
> +		if (val_z2 < 0)
> +			break;
> +
> +		/* Validate signal (avoid calculation using noise) */
> +		if (val_z1 > 64 && val_x > 64) {
> +			/*
> +			 * Calculate resistance between the plates
> +			 * lower resistance means higher pressure
> +			 */
> +			int r_x = (1000 * val_x) / VF_ADC_MAX;
> +
> +			val_p = (r_x * val_z2) / val_z1 - r_x;
> +
> +		} else {
> +			val_p = 2000;
> +		}
> +
> +		val_p = 2000 - val_p;
> +		dev_dbg(dev, "Measured values: x: %d, y: %d, z1: %d, z2: %d, "
> +			"p: %d\n", val_x, val_y, val_z1, val_z2, val_p);
> +
> +		/*
> +		 * If touch pressure is too low, stop measuring and reenable
> +		 * touch detection
> +		 */
> +		if (val_p < vf50_ts->min_pressure || val_p > 2000)
> +			break;
> +
> +		/*
> +		 * The pressure may not be enough for the first x and the
> +		 * second y measurement, but, the pressure is ok when the
> +		 * driver is doing the third and fourth measurement. To
> +		 * take care of this, we drop the first measurement always.
> +		 */
> +		if (discard_val_on_start) {
> +			discard_val_on_start = false;
> +		} else {
> +			/*
> +			 * Report touch position and sleep for
> +			 * next measurement
> +			 */
> +			input_report_abs(vf50_ts->ts_input,
> +					ABS_X, VF_ADC_MAX - val_x);
> +			input_report_abs(vf50_ts->ts_input,
> +					ABS_Y, VF_ADC_MAX - val_y);
> +			input_report_abs(vf50_ts->ts_input,
> +					ABS_PRESSURE, val_p);
> +			input_report_key(vf50_ts->ts_input, BTN_TOUCH, 1);
> +			input_sync(vf50_ts->ts_input);
> +		}
> +
> +		msleep(10);
> +	}
> +
> +	/* Report no more touch, reenable touch detection */
> +	input_report_abs(vf50_ts->ts_input, ABS_PRESSURE, 0);
> +	input_report_key(vf50_ts->ts_input, BTN_TOUCH, 0);
> +	input_sync(vf50_ts->ts_input);
> +
> +	vf50_ts_enable_touch_detection(vf50_ts);
> +
> +	/* Wait for the pull-up to be stable on high */
> +	msleep(10);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int vf50_ts_open(struct input_dev *dev_input)
> +{
> +	struct vf50_touch_device *touchdev = input_get_drvdata(dev_input);
> +	struct device *dev = &touchdev->pdev->dev;
> +
> +	dev_dbg(dev, "Input device %s opened, starting touch detection\n",
> +			dev_input->name);
> +
> +	touchdev->stop_touchscreen = false;
> +
> +	/* Mux detection before request IRQ, wait for pull-up to settle */
> +	vf50_ts_enable_touch_detection(touchdev);
> +	msleep(10);
> +
> +	return 0;
> +}
> +
> +static void vf50_ts_close(struct input_dev *dev_input)
> +{
> +	struct vf50_touch_device *touchdev = input_get_drvdata(dev_input);
> +	struct device *dev = &touchdev->pdev->dev;
> +
> +	touchdev->stop_touchscreen = true;
> +
> +	/* Make sure IRQ is not running past close */
> +	mb();
> +	synchronize_irq(touchdev->pen_irq);
> +
> +	gpiod_set_value(touchdev->gpio_ym, 0);
> +	pinctrl_pm_select_default_state(dev);
> +
> +	dev_dbg(dev, "Input device %s closed, disable touch detection\n",
> +		dev_input->name);
> +}
> +
> +static int vf50_ts_get_gpiod(struct device *dev,
> +	struct gpio_desc **gpio_d, const char *con_id, enum gpiod_flags flags)
> +{
> +	int error;
> +
> +	*gpio_d = devm_gpiod_get(dev, con_id, flags);
> +	if (IS_ERR(*gpio_d)) {
> +		error = PTR_ERR(*gpio_d);
> +		dev_err(dev, "Could not get gpio_%s %d\n", con_id, error);
> +		return error;
> +	}
> +
> +	return 0;
> +}
> +
> +static void vf50_ts_channel_release(void *data)
> +{
> +	struct iio_channel *channels = data;
> +
> +	iio_channel_release_all(channels);
> +}
> +
> +static int vf50_ts_probe(struct platform_device *pdev)
> +{
> +	struct input_dev *input;
> +	struct iio_channel *channels;
> +	struct device *dev = &pdev->dev;
> +	struct vf50_touch_device *touchdev;
> +	int num_adc_channels = 0;
> +	int error;
> +
> +	channels = iio_channel_get_all(dev);
> +	if (IS_ERR(channels))
> +		return PTR_ERR(channels);
> +
> +	error = devm_add_action(dev, vf50_ts_channel_release, channels);
> +	if (error) {
> +		iio_channel_release_all(channels);
> +		dev_err(dev, "Failed to register iio channel release action");
> +		return error;
> +	}
> +
> +	touchdev = devm_kzalloc(dev, sizeof(*touchdev), GFP_KERNEL);
> +	if (!touchdev)
> +		return -ENOMEM;
> +
> +	touchdev->pdev = pdev;
> +	touchdev->channels = channels;
> +
> +	while (channels[num_adc_channels].indio_dev)
> +		num_adc_channels++;
> +
> +	if (num_adc_channels != COLI_TOUCH_REQ_ADC_CHAN) {
> +		dev_err(dev, "Inadequate ADC channels specified\n");
> +		return -EINVAL;
> +	}
> +
> +	error = of_property_read_u32(dev->of_node, "vf50-ts-min-pressure",
> +				 &touchdev->min_pressure);
> +	if (error)
> +		return error;
> +
> +	input = devm_input_allocate_device(dev);
> +	if (!input) {
> +		dev_err(dev, "Failed to allocate TS input device\n");
> +		return -ENOMEM;
> +	}
> +
> +	platform_set_drvdata(pdev, touchdev);
> +
> +	input->name = DRIVER_NAME;
> +	input->id.bustype = BUS_HOST;
> +	input->dev.parent = dev;
> +	input->open = vf50_ts_open;
> +	input->close = vf50_ts_close;
> +
> +	input_set_capability(input, EV_KEY, BTN_TOUCH);
> +	input_set_abs_params(input, ABS_X, 0, VF_ADC_MAX, 0, 0);
> +	input_set_abs_params(input, ABS_Y, 0, VF_ADC_MAX, 0, 0);
> +	input_set_abs_params(input, ABS_PRESSURE, 0, VF_ADC_MAX, 0, 0);
> +
> +	touchdev->ts_input = input;
> +	input_set_drvdata(input, touchdev);
> +	error = input_register_device(input);
> +	if (error) {
> +		dev_err(dev, "Failed to register input device\n");
> +		return error;
> +	}
> +
> +	error = vf50_ts_get_gpiod(dev, &touchdev->gpio_xp,
> +				"xp", GPIOD_OUT_LOW);
> +	if (error)
> +		return error;
> +
> +	error = vf50_ts_get_gpiod(dev, &touchdev->gpio_xm,
> +				"xm", GPIOD_OUT_LOW);
> +	if (error)
> +		return error;
> +
> +	error = vf50_ts_get_gpiod(dev, &touchdev->gpio_yp,
> +				"yp", GPIOD_OUT_LOW);
> +	if (error)
> +		return error;
> +
> +	error = vf50_ts_get_gpiod(dev, &touchdev->gpio_ym,
> +				"ym", GPIOD_OUT_LOW);
> +	if (error)
> +		return error;
> +
> +	touchdev->pen_irq = platform_get_irq(pdev, 0);
> +	if (touchdev->pen_irq < 0)
> +		return touchdev->pen_irq;
> +
> +	error = devm_request_threaded_irq(dev, touchdev->pen_irq, NULL,
> +			vf50_ts_irq_bh, IRQF_ONESHOT,
> +			"vf50 touch", touchdev);
> +	if (error < 0)
> +		return error;
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id vf50_touch_of_match[] = {
> +	{ .compatible = "toradex,vf50-touchscreen", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, vf50_touch_of_match);
> +
> +static struct platform_driver vf50_touch_driver = {
> +	.driver = {
> +		.name = "toradex,vf50_touchctrl",
> +		.of_match_table = vf50_touch_of_match,
> +	},
> +	.probe = vf50_ts_probe,
> +};
> +
> +module_platform_driver(vf50_touch_driver);
> +
> +MODULE_AUTHOR("Sanchayan Maity");
> +MODULE_DESCRIPTION("Colibri VF50 Touchscreen driver");
> +MODULE_LICENSE("GPL");
> +MODULE_VERSION(DRV_VERSION);
> -- 
> 2.5.0
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-input" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

-- 
Dmitry

Re: [PATCH v5 1/3] ARM: dts: vf500-colibri: Add device tree node for touchscreen support

[maitysanchayan]

Hello Shawn,

The driver has landed in your tree. Can you queue this DT change for the same?

Thanks.

- Sanchayan.

On 15-09-01 18:06:53, Sanchayan Maity wrote:
> Add device tree node for touchscreen support on Colibri VF50. The
> touchscreen functionality on VF50 uses the ADC channels of Vybrid
> and some GPIOs. Also add pinctrl nodes for proper pinmux.
> 
> Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
> ---
>  arch/arm/boot/dts/vf500-colibri-eval-v3.dts |  5 +++
>  arch/arm/boot/dts/vf500-colibri.dtsi        | 47 +++++++++++++++++++++++++++++
>  2 files changed, 52 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/vf500-colibri-eval-v3.dts b/arch/arm/boot/dts/vf500-colibri-eval-v3.dts
> index 7fc782c..c3173fc 100644
> --- a/arch/arm/boot/dts/vf500-colibri-eval-v3.dts
> +++ b/arch/arm/boot/dts/vf500-colibri-eval-v3.dts
> @@ -15,3 +15,8 @@
>  	model = "Toradex Colibri VF50 on Colibri Evaluation Board";
>  	compatible = "toradex,vf500-colibri_vf50-on-eval", "toradex,vf500-colibri_vf50", "fsl,vf500";
>  };
> +
> +&touchscreen {
> +	vf50-ts-min-pressure = <200>;
> +	status = "okay";
> +};
> diff --git a/arch/arm/boot/dts/vf500-colibri.dtsi b/arch/arm/boot/dts/vf500-colibri.dtsi
> index cee34a3..84f091d 100644
> --- a/arch/arm/boot/dts/vf500-colibri.dtsi
> +++ b/arch/arm/boot/dts/vf500-colibri.dtsi
> @@ -17,4 +17,51 @@
>  	memory {
>  		reg = <0x80000000 0x8000000>;
>  	};
> +
> +	touchscreen: vf50-touchscreen {
> +		compatible = "toradex,vf50-touchscreen";
> +		io-channels = <&adc1 0>,<&adc0 0>,
> +				<&adc0 1>,<&adc1 2>;
> +		xp-gpios = <&gpio0 13 GPIO_ACTIVE_LOW>;
> +		xm-gpios = <&gpio2 29 GPIO_ACTIVE_HIGH>;
> +		yp-gpios = <&gpio0 12 GPIO_ACTIVE_LOW>;
> +		ym-gpios = <&gpio0 4 GPIO_ACTIVE_HIGH>;
> +		interrupt-parent = <&gpio0>;
> +		interrupts = <8 IRQ_TYPE_LEVEL_LOW>;
> +		pinctrl-names = "idle","default","gpios";
> +		pinctrl-0 = <&pinctrl_touchctrl_idle>;
> +		pinctrl-1 = <&pinctrl_touchctrl_default>;
> +		pinctrl-2 = <&pinctrl_touchctrl_gpios>;
> +		vf50-ts-min-pressure = <200>;
> +		status = "disabled";
> +	};
> +};
> +
> +&iomuxc {
> +	vf610-colibri {
> +		pinctrl_touchctrl_idle: touchctrl_idle {
> +			fsl,pins = <
> +				VF610_PAD_PTA18__GPIO_8		0x006d
> +				VF610_PAD_PTA19__GPIO_9		0x006c
> +				>;
> +		};
> +
> +		pinctrl_touchctrl_default: touchctrl_default {
> +			fsl,pins = <
> +				VF610_PAD_PTA18__ADC0_SE0	0x0040
> +				VF610_PAD_PTA19__ADC0_SE1	0x0040
> +				VF610_PAD_PTA16__ADC1_SE0	0x0040
> +				VF610_PAD_PTB2__ADC1_SE2	0x0040
> +				>;
> +		};
> +
> +		pinctrl_touchctrl_gpios: touchctrl_gpios {
> +			fsl,pins = <
> +				VF610_PAD_PTA23__GPIO_13	0x22e9
> +				VF610_PAD_PTB23__GPIO_93	0x22e9
> +				VF610_PAD_PTA22__GPIO_12	0x22e9
> +				VF610_PAD_PTA11__GPIO_4		0x22e9
> +				>;
> +		};
> +	};
>  };
> -- 
> 2.5.0
> 

Re: [PATCH v5 1/3] ARM: dts: vf500-colibri: Add device tree node for touchscreen support

[Shawn Guo]

On Tue, Sep 01, 2015 at 06:06:53PM +0530, Sanchayan Maity wrote:
> Add device tree node for touchscreen support on Colibri VF50. The
> touchscreen functionality on VF50 uses the ADC channels of Vybrid
> and some GPIOs. Also add pinctrl nodes for proper pinmux.
> 
> Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>

Applied, thanks.