diff mbox series

[v2,2/2] Input: add Imagis touchscreen driver

Message ID 20220210163708.162866-3-markuss.broks@gmail.com (mailing list archive)
State Superseded
Headers show
Series Add support for Imagis touchscreens | expand

Commit Message

Markuss Broks Feb. 10, 2022, 4:37 p.m. UTC 
Add support for the IST3038C touchscreen IC from Imagis, based on
downstream driver. The driver supports multi-touch (10 touch points)
The IST3038C IC supports touch keys, but the support isn't added
because the touch screen used for testing doesn't utilize touch keys.
Looking at the downstream driver, it is possible to add support
for other Imagis ICs of IST30**C series.

Signed-off-by: Markuss Broks <markuss.broks@gmail.com>
---
 MAINTAINERS                        |   6 +
 drivers/input/touchscreen/Kconfig  |  10 +
 drivers/input/touchscreen/Makefile |   1 +
 drivers/input/touchscreen/imagis.c | 329 +++++++++++++++++++++++++++++
 4 files changed, 346 insertions(+)
 create mode 100644 drivers/input/touchscreen/imagis.c

Comments

Jeff LaBundy Feb. 11, 2022, 12:01 a.m. UTC | #1 
Hi Markuss,

Neat little driver! Some humble feedback below.

On Thu, Feb 10, 2022 at 06:37:07PM +0200, Markuss Broks wrote:
> Add support for the IST3038C touchscreen IC from Imagis, based on
> downstream driver. The driver supports multi-touch (10 touch points)
> The IST3038C IC supports touch keys, but the support isn't added
> because the touch screen used for testing doesn't utilize touch keys.
> Looking at the downstream driver, it is possible to add support
> for other Imagis ICs of IST30**C series.
> 
> Signed-off-by: Markuss Broks <markuss.broks@gmail.com>
> ---
>  MAINTAINERS                        |   6 +
>  drivers/input/touchscreen/Kconfig  |  10 +
>  drivers/input/touchscreen/Makefile |   1 +
>  drivers/input/touchscreen/imagis.c | 329 +++++++++++++++++++++++++++++
>  4 files changed, 346 insertions(+)
>  create mode 100644 drivers/input/touchscreen/imagis.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index a899828a8d4e..f7f717ae926a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -9405,6 +9405,12 @@ F:	Documentation/devicetree/bindings/iio/afe/current-sense-shunt.yaml
>  F:	Documentation/devicetree/bindings/iio/afe/voltage-divider.yaml
>  F:	drivers/iio/afe/iio-rescale.c
>  
> +IMAGIS TOUCHSCREEN DRIVER
> +M:	Markuss Broks <markuss.broks@gmail.com>
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/input/touchscreen/imagis,ist3038c.yaml
> +F:	drivers/input/touchscreen/imagis.c
> +
>  IKANOS/ADI EAGLE ADSL USB DRIVER
>  M:	Matthieu Castet <castet.matthieu@free.fr>
>  M:	Stanislaw Gruszka <stf_xl@wp.pl>
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index 2f6adfb7b938..6810b4b094e8 100644
> --- a/drivers/input/touchscreen/Kconfig
> +++ b/drivers/input/touchscreen/Kconfig
> @@ -1367,4 +1367,14 @@ config TOUCHSCREEN_ZINITIX
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called zinitix.
>  
> +config TOUCHSCREEN_IMAGIS
> +	tristate "Imagis touchscreen support"
> +	depends on I2C
> +	help
> +		Say Y here if you have an Imagis IST30xxC touchscreen.
> +		If unsure, say N.
> +
> +		To compile this driver as a module, choose M here: the
> +		module will be called imagis.
> +
>  endif
> diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
> index 39a8127cf6a5..989bb1d563d3 100644
> --- a/drivers/input/touchscreen/Makefile
> +++ b/drivers/input/touchscreen/Makefile
> @@ -115,3 +115,4 @@ obj-$(CONFIG_TOUCHSCREEN_ROHM_BU21023)	+= rohm_bu21023.o
>  obj-$(CONFIG_TOUCHSCREEN_RASPBERRYPI_FW)	+= raspberrypi-ts.o
>  obj-$(CONFIG_TOUCHSCREEN_IQS5XX)	+= iqs5xx.o
>  obj-$(CONFIG_TOUCHSCREEN_ZINITIX)	+= zinitix.o
> +obj-$(CONFIG_TOUCHSCREEN_IMAGIS)	+= imagis.o
> diff --git a/drivers/input/touchscreen/imagis.c b/drivers/input/touchscreen/imagis.c
> new file mode 100644
> index 000000000000..308f097a95c1
> --- /dev/null
> +++ b/drivers/input/touchscreen/imagis.c
> @@ -0,0 +1,329 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/property.h>
> +#include <linux/input.h>
> +#include <linux/input/mt.h>
> +#include <linux/input/touchscreen.h>
> +
> +#define IST3038_ADDR_LEN		4
> +#define IST3038_DATA_LEN		4
> +#define IST3038_HIB_ACCESS		(0x800B << 16)
> +#define IST3038_DIRECT_ACCESS   BIT(31)
> +#define IST3038_REG_CHIPID      0x40001000
> +
> +#define IST3038_REG_HIB_BASE		(0x30000100)
> +#define IST3038_REG_TOUCH_STATUS        (IST3038_REG_HIB_BASE | IST3038_HIB_ACCESS)
> +#define IST3038_REG_TOUCH_COORD        (IST3038_REG_HIB_BASE | IST3038_HIB_ACCESS | 0x8)
> +#define IST3038_REG_INTR_MESSAGE        (IST3038_REG_HIB_BASE | IST3038_HIB_ACCESS | 0x4)
> +
> +#define IST3038C_WHOAMI			0x38c
> +#define CHIP_ON_DELAY				60 // ms
> +
> +#define I2C_RETRY_COUNT			3
> +
> +#define MAX_SUPPORTED_FINGER_NUM		10

Please prefix all #defines with a common namespace (e.g. IST3038C).

> +
> +struct imagis_ts {
> +	struct i2c_client *client;
> +	struct input_dev *input_dev;
> +	struct touchscreen_properties prop;
> +	struct regulator_bulk_data supplies[2];
> +};
> +
> +static int imagis_i2c_read_reg(struct imagis_ts *ts,
> +			       unsigned int reg, unsigned int *buffer)
> +{
> +	unsigned int reg_be = __cpu_to_be32(reg);

Technically this type should be __be32. Also, why to use __cpu_to_be32 in
place of cpu_to_be32?

> +	struct i2c_msg msg[] = {
> +		{
> +			.addr = ts->client->addr,
> +			.flags = 0,
> +			.buf = (unsigned char *)&reg_be,
> +			.len = IST3038_ADDR_LEN,

I do not think we need these #defines; just use sizeof(reg_be).

> +		}, {
> +			.addr = ts->client->addr,
> +			.flags = I2C_M_RD,
> +			.buf = (unsigned char *)buffer,
> +			.len = IST3038_DATA_LEN,

Same here.

> +		},
> +	};
> +	int res;

For these return variables that may be positive or negative, it is more
common to use 'ret'.

> +	int error;
> +	int retry = I2C_RETRY_COUNT;
> +
> +	do {
> +		res = i2c_transfer(ts->client->adapter, msg, ARRAY_SIZE(msg));
> +		if (res == ARRAY_SIZE(msg)) {
> +			*buffer = __be32_to_cpu(*buffer);
> +			return 0;
> +		}
> +
> +		error = res < 0 ? res : -EIO;
> +		dev_err(&ts->client->dev,
> +			"%s - i2c_transfer failed: %d (%d)\n",
> +			__func__, error, res);

Does this controller suffer some sort of erratum that requires I2C reads
to be retried? If so, it would be handy to include a comment here as to
why we do not expect the read to be successful right away.

> +	} while (--retry);
> +
> +	return error;
> +}
> +
> +static irqreturn_t imagis_interrupt(int irq, void *dev_id)
> +{
> +	struct imagis_ts *ts = dev_id;
> +	unsigned int finger_status, intr_message;
> +	int ret, i, finger_count, finger_pressed;

Please use 'error' for return values that only return 0 or an -errno.

> +
> +	ret = imagis_i2c_read_reg(ts, IST3038_REG_INTR_MESSAGE, &intr_message);
> +	if (ret) {
> +		dev_err(&ts->client->dev, "failed to read the interrupt message\n");
> +		return IRQ_HANDLED;
> +	}
> +
> +	finger_count = (intr_message >> 12) & 0xF;
> +	finger_pressed = intr_message & 0x3FF;

Please #define bit shift and masks, with GENMASK used for the latter.

> +	if (finger_count > 10) {
> +		dev_err(&ts->client->dev, "finger count is more than maximum supported\n");
> +		return IRQ_HANDLED;
> +	}

You seem to have #defined the maximum finger count but it is not used here.

> +
> +	for (i = 0; i < finger_count; i++) {
> +		ret = imagis_i2c_read_reg(ts, IST3038_REG_TOUCH_COORD + (i * 4), &finger_status);
> +		if (ret) {
> +			dev_err(&ts->client->dev, "failed to read coordinates for finger %d\n", i);
> +			return IRQ_HANDLED;
> +		}

Can this not be done in a bulk read so as to save up to 10 stop/starts?

Maybe it makes sense to define a bulk read function, with imagis_i2c_read
simply calling the bulk read function with a fixed length.

> +		input_mt_slot(ts->input_dev, i);
> +		input_mt_report_slot_state(ts->input_dev, MT_TOOL_FINGER,
> +					   (finger_pressed & BIT(i)) ? 1 : 0);

No need for the ternary operator here; just pass the boolean as-is.

> +		touchscreen_report_pos(ts->input_dev, &ts->prop,
> +				       (finger_status >> 12) & 0xFFF, finger_status & 0xFFF, 1);
> +		input_report_abs(ts->input_dev, ABS_MT_TOUCH_MAJOR, (finger_status >> 24) & 0xFFF);
> +	}
> +	input_mt_sync_frame(ts->input_dev);
> +	input_sync(ts->input_dev);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int imagis_start(struct imagis_ts *ts)
> +{
> +	int error;
> +
> +	error = regulator_bulk_enable(ARRAY_SIZE(ts->supplies),
> +				      ts->supplies);
> +	if (error) {
> +		dev_err(&ts->client->dev,
> +			"Failed to enable regulators: %d\n", error);
> +		return error;
> +	}
> +
> +	msleep(CHIP_ON_DELAY);
> +
> +	enable_irq(ts->client->irq);

This is going to cause unbalanced irq enable/disable because you're calling
this function from probe.

> +	return 0;
> +}
> +
> +static int imagis_stop(struct imagis_ts *ts)
> +{
> +	int error;
> +
> +	disable_irq(ts->client->irq);
> +
> +	error = regulator_bulk_disable(ARRAY_SIZE(ts->supplies),
> +				       ts->supplies);
> +	if (error) {
> +		dev_err(&ts->client->dev,
> +			"Failed to disable regulators: %d\n", error);
> +		return error;
> +	}
> +
> +	return 0;

This is largely personal preference, but this is shorter:

error = ...
if (error)
        dev_err(...);

return error;

> +}
> +
> +static int imagis_input_open(struct input_dev *dev)
> +{
> +	struct imagis_ts *ts = input_get_drvdata(dev);
> +
> +	return imagis_start(ts);
> +}
> +
> +static void imagis_input_close(struct input_dev *dev)
> +{
> +	struct imagis_ts *ts = input_get_drvdata(dev);
> +
> +	imagis_stop(ts);
> +}
> +
> +static int imagis_init_input_dev(struct imagis_ts *ts)
> +{
> +	struct input_dev *input_dev;
> +	int error;
> +
> +	input_dev = devm_input_allocate_device(&ts->client->dev);
> +	if (!input_dev) {
> +		dev_err(&ts->client->dev,
> +			"Failed to allocate input device.");
> +		return -ENOMEM;
> +	}

No need for a message here.

> +
> +	ts->input_dev = input_dev;
> +
> +	input_dev->name = "Imagis capacitive touchscreen";
> +	input_dev->phys = "input/ts";
> +	input_dev->id.bustype = BUS_I2C;
> +	input_dev->open = imagis_input_open;
> +	input_dev->close = imagis_input_close;
> +
> +	input_set_drvdata(input_dev, ts);
> +
> +	input_set_capability(input_dev, EV_ABS, ABS_MT_POSITION_X);
> +	input_set_capability(input_dev, EV_ABS, ABS_MT_POSITION_Y);
> +	input_set_abs_params(input_dev, ABS_MT_WIDTH_MAJOR, 0, 255, 0, 0);

WIDTH is advertised here but never reported in the interrupt handler.

> +	input_set_abs_params(input_dev, ABS_MT_TOUCH_MAJOR, 0, 255, 0, 0);
> +
> +	touchscreen_parse_properties(input_dev, true, &ts->prop);
> +	if (!ts->prop.max_x || !ts->prop.max_y) {
> +		dev_err(&ts->client->dev,
> +			"Touchscreen-size-x and/or touchscreen-size-y not set in dts\n");
> +		return -EINVAL;
> +	}
> +
> +	error = input_mt_init_slots(input_dev, MAX_SUPPORTED_FINGER_NUM,
> +				    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
> +	if (error) {
> +		dev_err(&ts->client->dev,
> +			"Failed to initialize MT slots: %d", error);
> +		return error;
> +	}
> +
> +	error = input_register_device(input_dev);
> +	if (error) {
> +		dev_err(&ts->client->dev,
> +			"Failed to register input device: %d", error);
> +		return error;
> +	}

I suggest using the device-managed version here, as you have no remove callback.

> +
> +	return 0;
> +}
> +
> +static int imagis_init_regulators(struct imagis_ts *ts)
> +{
> +	struct i2c_client *client = ts->client;
> +	int error;
> +
> +	ts->supplies[0].supply = "vdd";
> +	ts->supplies[1].supply = "vddio";

How does this work?

> +	error = devm_regulator_bulk_get(&client->dev,
> +					ARRAY_SIZE(ts->supplies),
> +					ts->supplies);
> +	if (error < 0) {
> +		dev_err(&client->dev, "Failed to get regulators: %d\n", error);
> +		return error;
> +	}
> +
> +	return 0;
> +}
> +
> +static int imagis_probe(struct i2c_client *i2c)
> +{
> +	struct device *dev;
> +	struct imagis_ts *ts;
> +	int chip_id, ret;
> +
> +	dev = &i2c->dev;
> +
> +	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
> +	if (!ts)
> +		return -ENOMEM;
> +
> +	ts->client = i2c;
> +
> +	ret = devm_request_threaded_irq(dev, i2c->irq,
> +					NULL, imagis_interrupt,
> +					IRQF_ONESHOT | IRQF_TRIGGER_FALLING,
> +					"imagis-touchscreen", ts);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "IRQ allocation failure: %d\n", ret);

Are you sure it's safe to enable interrupts before the controller has
been powered?

> +
> +	ret = imagis_init_regulators(ts);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "regulator init error: %d\n", ret);
> +
> +	ret = imagis_start(ts);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "regulator enable error: %d\n", ret);
> +
> +	ret = imagis_i2c_read_reg(ts, IST3038_REG_CHIPID | IST3038_DIRECT_ACCESS, &chip_id);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "chip ID read failure: %d\n", ret);
> +
> +	if (chip_id == IST3038C_WHOAMI)
> +		dev_info(dev, "Detected IST3038C chip\n");

This should be dev_dbg, if at all.

> +	else
> +		return dev_err_probe(dev, -EINVAL, "unknown chip ID: 0x%x\n", chip_id);

Usually you want to ID the controller as early as possibe, to avoid wasting
time allocating resources if there is a problem.

> +
> +	ret = imagis_init_input_dev(ts);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "input subsystem init error: %d\n", ret);
> +

Just for my own understanding, this controller needs no configuration or
register writes after power-on?

> +	return 0;
> +}
> +
> +static int __maybe_unused imagis_suspend(struct device *dev)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct imagis_ts *ts = i2c_get_clientdata(client);
> +
> +	mutex_lock(&ts->input_dev->mutex);
> +
> +	if (input_device_enabled(ts->input_dev))
> +		imagis_stop(ts);

I would prefer to salvage the return value and return it after mutex unlock.

> +
> +	mutex_unlock(&ts->input_dev->mutex);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused imagis_resume(struct device *dev)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct imagis_ts *ts = i2c_get_clientdata(client);
> +
> +	mutex_lock(&ts->input_dev->mutex);
> +
> +	if (input_device_enabled(ts->input_dev))
> +		imagis_start(ts);
> +
> +	mutex_unlock(&ts->input_dev->mutex);
> +
> +	return 0;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(imagis_pm_ops, imagis_suspend, imagis_resume);
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id imagis_of_match[] = {
> +	{ .compatible = "imagis,ist3038c", },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(i2c, imagis_of_match);
> +#endif
> +
> +static struct i2c_driver imagis_ts_driver = {
> +	.driver = {
> +		   .name = "imagis-touchscreen",
> +		   .pm = &imagis_pm_ops,
> +		   .of_match_table = of_match_ptr(imagis_of_match),
> +	},
> +	.probe_new	= imagis_probe,
> +};
> +
> +module_i2c_driver(imagis_ts_driver);
> +
> +MODULE_DESCRIPTION("Imagis IST3038C Touchscreen Driver");
> +MODULE_AUTHOR("Markuss Broks <markuss.broks@gmail.com>");
> +MODULE_LICENSE("GPL");
> -- 
> 2.35.0
> 

Kind regards,
Jeff LaBundy
Jeff LaBundy Feb. 11, 2022, 12:50 a.m. UTC | #2 
Hi Markuss,

One tiny correction to my previous feedback.

On Thu, Feb 10, 2022 at 06:01:03PM -0600, Jeff LaBundy wrote:
> Hi Markuss,
> 
> Neat little driver! Some humble feedback below.
> 

[...]

> > +	error = input_register_device(input_dev);
> > +	if (error) {
> > +		dev_err(&ts->client->dev,
> > +			"Failed to register input device: %d", error);
> > +		return error;
> > +	}
> 
> I suggest using the device-managed version here, as you have no remove callback.
> 

Please ignore this bit :)

[...]

Kind regards,
Jeff LaBundy
diff mbox series

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index a899828a8d4e..f7f717ae926a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9405,6 +9405,12 @@  F:	Documentation/devicetree/bindings/iio/afe/current-sense-shunt.yaml
 F:	Documentation/devicetree/bindings/iio/afe/voltage-divider.yaml
 F:	drivers/iio/afe/iio-rescale.c
 
+IMAGIS TOUCHSCREEN DRIVER
+M:	Markuss Broks <markuss.broks@gmail.com>
+S:	Maintained
+F:	Documentation/devicetree/bindings/input/touchscreen/imagis,ist3038c.yaml
+F:	drivers/input/touchscreen/imagis.c
+
 IKANOS/ADI EAGLE ADSL USB DRIVER
 M:	Matthieu Castet <castet.matthieu@free.fr>
 M:	Stanislaw Gruszka <stf_xl@wp.pl>
diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index 2f6adfb7b938..6810b4b094e8 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -1367,4 +1367,14 @@  config TOUCHSCREEN_ZINITIX
 	  To compile this driver as a module, choose M here: the
 	  module will be called zinitix.
 
+config TOUCHSCREEN_IMAGIS
+	tristate "Imagis touchscreen support"
+	depends on I2C
+	help
+		Say Y here if you have an Imagis IST30xxC touchscreen.
+		If unsure, say N.
+
+		To compile this driver as a module, choose M here: the
+		module will be called imagis.
+
 endif
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 39a8127cf6a5..989bb1d563d3 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -115,3 +115,4 @@  obj-$(CONFIG_TOUCHSCREEN_ROHM_BU21023)	+= rohm_bu21023.o
 obj-$(CONFIG_TOUCHSCREEN_RASPBERRYPI_FW)	+= raspberrypi-ts.o
 obj-$(CONFIG_TOUCHSCREEN_IQS5XX)	+= iqs5xx.o
 obj-$(CONFIG_TOUCHSCREEN_ZINITIX)	+= zinitix.o
+obj-$(CONFIG_TOUCHSCREEN_IMAGIS)	+= imagis.o
diff --git a/drivers/input/touchscreen/imagis.c b/drivers/input/touchscreen/imagis.c
new file mode 100644
index 000000000000..308f097a95c1
--- /dev/null
+++ b/drivers/input/touchscreen/imagis.c
@@ -0,0 +1,329 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/input/touchscreen.h>
+
+#define IST3038_ADDR_LEN		4
+#define IST3038_DATA_LEN		4
+#define IST3038_HIB_ACCESS		(0x800B << 16)
+#define IST3038_DIRECT_ACCESS   BIT(31)
+#define IST3038_REG_CHIPID      0x40001000
+
+#define IST3038_REG_HIB_BASE		(0x30000100)
+#define IST3038_REG_TOUCH_STATUS        (IST3038_REG_HIB_BASE | IST3038_HIB_ACCESS)
+#define IST3038_REG_TOUCH_COORD        (IST3038_REG_HIB_BASE | IST3038_HIB_ACCESS | 0x8)
+#define IST3038_REG_INTR_MESSAGE        (IST3038_REG_HIB_BASE | IST3038_HIB_ACCESS | 0x4)
+
+#define IST3038C_WHOAMI			0x38c
+#define CHIP_ON_DELAY				60 // ms
+
+#define I2C_RETRY_COUNT			3
+
+#define MAX_SUPPORTED_FINGER_NUM		10
+
+struct imagis_ts {
+	struct i2c_client *client;
+	struct input_dev *input_dev;
+	struct touchscreen_properties prop;
+	struct regulator_bulk_data supplies[2];
+};
+
+static int imagis_i2c_read_reg(struct imagis_ts *ts,
+			       unsigned int reg, unsigned int *buffer)
+{
+	unsigned int reg_be = __cpu_to_be32(reg);
+	struct i2c_msg msg[] = {
+		{
+			.addr = ts->client->addr,
+			.flags = 0,
+			.buf = (unsigned char *)&reg_be,
+			.len = IST3038_ADDR_LEN,
+		}, {
+			.addr = ts->client->addr,
+			.flags = I2C_M_RD,
+			.buf = (unsigned char *)buffer,
+			.len = IST3038_DATA_LEN,
+		},
+	};
+	int res;
+	int error;
+	int retry = I2C_RETRY_COUNT;
+
+	do {
+		res = i2c_transfer(ts->client->adapter, msg, ARRAY_SIZE(msg));
+		if (res == ARRAY_SIZE(msg)) {
+			*buffer = __be32_to_cpu(*buffer);
+			return 0;
+		}
+
+		error = res < 0 ? res : -EIO;
+		dev_err(&ts->client->dev,
+			"%s - i2c_transfer failed: %d (%d)\n",
+			__func__, error, res);
+	} while (--retry);
+
+	return error;
+}
+
+static irqreturn_t imagis_interrupt(int irq, void *dev_id)
+{
+	struct imagis_ts *ts = dev_id;
+	unsigned int finger_status, intr_message;
+	int ret, i, finger_count, finger_pressed;
+
+	ret = imagis_i2c_read_reg(ts, IST3038_REG_INTR_MESSAGE, &intr_message);
+	if (ret) {
+		dev_err(&ts->client->dev, "failed to read the interrupt message\n");
+		return IRQ_HANDLED;
+	}
+
+	finger_count = (intr_message >> 12) & 0xF;
+	finger_pressed = intr_message & 0x3FF;
+	if (finger_count > 10) {
+		dev_err(&ts->client->dev, "finger count is more than maximum supported\n");
+		return IRQ_HANDLED;
+	}
+
+	for (i = 0; i < finger_count; i++) {
+		ret = imagis_i2c_read_reg(ts, IST3038_REG_TOUCH_COORD + (i * 4), &finger_status);
+		if (ret) {
+			dev_err(&ts->client->dev, "failed to read coordinates for finger %d\n", i);
+			return IRQ_HANDLED;
+		}
+		input_mt_slot(ts->input_dev, i);
+		input_mt_report_slot_state(ts->input_dev, MT_TOOL_FINGER,
+					   (finger_pressed & BIT(i)) ? 1 : 0);
+		touchscreen_report_pos(ts->input_dev, &ts->prop,
+				       (finger_status >> 12) & 0xFFF, finger_status & 0xFFF, 1);
+		input_report_abs(ts->input_dev, ABS_MT_TOUCH_MAJOR, (finger_status >> 24) & 0xFFF);
+	}
+	input_mt_sync_frame(ts->input_dev);
+	input_sync(ts->input_dev);
+
+	return IRQ_HANDLED;
+}
+
+static int imagis_start(struct imagis_ts *ts)
+{
+	int error;
+
+	error = regulator_bulk_enable(ARRAY_SIZE(ts->supplies),
+				      ts->supplies);
+	if (error) {
+		dev_err(&ts->client->dev,
+			"Failed to enable regulators: %d\n", error);
+		return error;
+	}
+
+	msleep(CHIP_ON_DELAY);
+
+	enable_irq(ts->client->irq);
+	return 0;
+}
+
+static int imagis_stop(struct imagis_ts *ts)
+{
+	int error;
+
+	disable_irq(ts->client->irq);
+
+	error = regulator_bulk_disable(ARRAY_SIZE(ts->supplies),
+				       ts->supplies);
+	if (error) {
+		dev_err(&ts->client->dev,
+			"Failed to disable regulators: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int imagis_input_open(struct input_dev *dev)
+{
+	struct imagis_ts *ts = input_get_drvdata(dev);
+
+	return imagis_start(ts);
+}
+
+static void imagis_input_close(struct input_dev *dev)
+{
+	struct imagis_ts *ts = input_get_drvdata(dev);
+
+	imagis_stop(ts);
+}
+
+static int imagis_init_input_dev(struct imagis_ts *ts)
+{
+	struct input_dev *input_dev;
+	int error;
+
+	input_dev = devm_input_allocate_device(&ts->client->dev);
+	if (!input_dev) {
+		dev_err(&ts->client->dev,
+			"Failed to allocate input device.");
+		return -ENOMEM;
+	}
+
+	ts->input_dev = input_dev;
+
+	input_dev->name = "Imagis capacitive touchscreen";
+	input_dev->phys = "input/ts";
+	input_dev->id.bustype = BUS_I2C;
+	input_dev->open = imagis_input_open;
+	input_dev->close = imagis_input_close;
+
+	input_set_drvdata(input_dev, ts);
+
+	input_set_capability(input_dev, EV_ABS, ABS_MT_POSITION_X);
+	input_set_capability(input_dev, EV_ABS, ABS_MT_POSITION_Y);
+	input_set_abs_params(input_dev, ABS_MT_WIDTH_MAJOR, 0, 255, 0, 0);
+	input_set_abs_params(input_dev, ABS_MT_TOUCH_MAJOR, 0, 255, 0, 0);
+
+	touchscreen_parse_properties(input_dev, true, &ts->prop);
+	if (!ts->prop.max_x || !ts->prop.max_y) {
+		dev_err(&ts->client->dev,
+			"Touchscreen-size-x and/or touchscreen-size-y not set in dts\n");
+		return -EINVAL;
+	}
+
+	error = input_mt_init_slots(input_dev, MAX_SUPPORTED_FINGER_NUM,
+				    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
+	if (error) {
+		dev_err(&ts->client->dev,
+			"Failed to initialize MT slots: %d", error);
+		return error;
+	}
+
+	error = input_register_device(input_dev);
+	if (error) {
+		dev_err(&ts->client->dev,
+			"Failed to register input device: %d", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int imagis_init_regulators(struct imagis_ts *ts)
+{
+	struct i2c_client *client = ts->client;
+	int error;
+
+	ts->supplies[0].supply = "vdd";
+	ts->supplies[1].supply = "vddio";
+	error = devm_regulator_bulk_get(&client->dev,
+					ARRAY_SIZE(ts->supplies),
+					ts->supplies);
+	if (error < 0) {
+		dev_err(&client->dev, "Failed to get regulators: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int imagis_probe(struct i2c_client *i2c)
+{
+	struct device *dev;
+	struct imagis_ts *ts;
+	int chip_id, ret;
+
+	dev = &i2c->dev;
+
+	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	ts->client = i2c;
+
+	ret = devm_request_threaded_irq(dev, i2c->irq,
+					NULL, imagis_interrupt,
+					IRQF_ONESHOT | IRQF_TRIGGER_FALLING,
+					"imagis-touchscreen", ts);
+	if (ret)
+		return dev_err_probe(dev, ret, "IRQ allocation failure: %d\n", ret);
+
+	ret = imagis_init_regulators(ts);
+	if (ret)
+		return dev_err_probe(dev, ret, "regulator init error: %d\n", ret);
+
+	ret = imagis_start(ts);
+	if (ret)
+		return dev_err_probe(dev, ret, "regulator enable error: %d\n", ret);
+
+	ret = imagis_i2c_read_reg(ts, IST3038_REG_CHIPID | IST3038_DIRECT_ACCESS, &chip_id);
+	if (ret)
+		return dev_err_probe(dev, ret, "chip ID read failure: %d\n", ret);
+
+	if (chip_id == IST3038C_WHOAMI)
+		dev_info(dev, "Detected IST3038C chip\n");
+	else
+		return dev_err_probe(dev, -EINVAL, "unknown chip ID: 0x%x\n", chip_id);
+
+	ret = imagis_init_input_dev(ts);
+	if (ret)
+		return dev_err_probe(dev, ret, "input subsystem init error: %d\n", ret);
+
+	return 0;
+}
+
+static int __maybe_unused imagis_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct imagis_ts *ts = i2c_get_clientdata(client);
+
+	mutex_lock(&ts->input_dev->mutex);
+
+	if (input_device_enabled(ts->input_dev))
+		imagis_stop(ts);
+
+	mutex_unlock(&ts->input_dev->mutex);
+
+	return 0;
+}
+
+static int __maybe_unused imagis_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct imagis_ts *ts = i2c_get_clientdata(client);
+
+	mutex_lock(&ts->input_dev->mutex);
+
+	if (input_device_enabled(ts->input_dev))
+		imagis_start(ts);
+
+	mutex_unlock(&ts->input_dev->mutex);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(imagis_pm_ops, imagis_suspend, imagis_resume);
+
+#ifdef CONFIG_OF
+static const struct of_device_id imagis_of_match[] = {
+	{ .compatible = "imagis,ist3038c", },
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, imagis_of_match);
+#endif
+
+static struct i2c_driver imagis_ts_driver = {
+	.driver = {
+		   .name = "imagis-touchscreen",
+		   .pm = &imagis_pm_ops,
+		   .of_match_table = of_match_ptr(imagis_of_match),
+	},
+	.probe_new	= imagis_probe,
+};
+
+module_i2c_driver(imagis_ts_driver);
+
+MODULE_DESCRIPTION("Imagis IST3038C Touchscreen Driver");
+MODULE_AUTHOR("Markuss Broks <markuss.broks@gmail.com>");
+MODULE_LICENSE("GPL");