[PATCHv7,1/4] Input: tsc2007: Add device tree support.

Commit Message

Denis Carikli Oct. 24, 2013, 12:42 p.m. UTC

Cc: Rob Herring <[e-mail]>
Cc: Pawel Moll <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Stephen Warren <[e-mail]>
Cc: Ian Campbell <[e-mail]>
Cc: [e-mail]
Cc: Dmitry Torokhov <[e-mail]>
Cc: [e-mail]
Cc: Sascha Hauer <[e-mail]>
Cc: [e-mail]
Cc: Lothar Waßmann <[e-mail]>
Cc: Eric Bénard <[e-mail]>
Signed-off-by: Denis Carikli <[e-mail]>
---
ChangeLog v6->v7:
- One small whitespace cleanup.
- The properties specific to that driver are now prefixed with "ti,".
- The ti,fuzzy property has now better documentation.
---
 .../bindings/input/touchscreen/tsc2007.txt         |   45 +++++
 drivers/input/touchscreen/tsc2007.c                |  194 +++++++++++++++-----
 2 files changed, 198 insertions(+), 41 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt

Comments

Thierry Reding Oct. 24, 2013, 3:17 p.m. UTC | #1

On Thu, Oct 24, 2013 at 02:42:13PM +0200, Denis Carikli wrote:
> Cc: Rob Herring <[e-mail]>
> Cc: Pawel Moll <[e-mail]>
> Cc: Mark Rutland <[e-mail]>
> Cc: Stephen Warren <[e-mail]>
> Cc: Ian Campbell <[e-mail]>
> Cc: [e-mail]
> Cc: Dmitry Torokhov <[e-mail]>
> Cc: [e-mail]
> Cc: Sascha Hauer <[e-mail]>
> Cc: [e-mail]
> Cc: Lothar Waßmann <[e-mail]>
> Cc: Eric Bénard <[e-mail]>
> Signed-off-by: Denis Carikli <[e-mail]>
> ---
> ChangeLog v6->v7:
> - One small whitespace cleanup.
> - The properties specific to that driver are now prefixed with "ti,".
> - The ti,fuzzy property has now better documentation.
> ---
>  .../bindings/input/touchscreen/tsc2007.txt         |   45 +++++
>  drivers/input/touchscreen/tsc2007.c                |  194 +++++++++++++++-----
>  2 files changed, 198 insertions(+), 41 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt
> 
> diff --git a/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt b/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt
> new file mode 100644
> index 0000000..516b63b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt
> @@ -0,0 +1,45 @@
> +* Texas Instruments tsc2007 touchscreen controller
> +
> +Required properties:
> +- compatible: must be "ti,tsc2007".
> +- reg: I2C address of the chip.
> +- ti,x-plate-ohms: X-plate resistance in ohms.
> +
> +Optional properties:
> +- gpios: the interrupt gpio the chip is connected to (trough the penirq pin)
> +  (see GPIO binding[2] for more details).
> +- interrupt-parent: the phandle for the gpio controller
> +  (see interrupt binding[1]).
> +- interrupts: (gpio) interrupt to which the chip is connected
> +  (see interrupt binding[1]).
> +- pinctrl-0: Should specify pin control groups used for the gpio
> +  (see pinctrl bindings[0]).
> +- pinctrl-names: Should contain only one value - "default"
> +  (see pinctrl bindings[0]).

Also I haven't seen a response as to why this can't be handled by the
GPIO driver. Adding Linus Walleij, perhaps he knows a more definitive
answer.

Linus, the issue here is that the pinctrl properties for this chip are
supposed to pinmux the pendown GPIO for this chip. I was under the
impression that this should be handled by the GPIO controller itself, so
that when gpio_request() was called on a pin it would be the GPIO
controller driver's responsibility to pinmux it appropriately.

> +- ti,max-rt: maximum pressure.
> +- ti,fuzzy: specifies the absolute input fuzz value.
> +  If set, it will permit noise in the data up to +- the value given to the fuzz
> +  parameter, that is used to filter noise from the event stream.

Any reason why these can't be specified per axis? From my experience
with this chip it can make sense to use different values for the
different axes. Well, perhaps X and Y axes can share one fuzz factor,
but the Z axis is sometimes different.

You also modify the driver to ignore the X and Z axes fuzz factor even
for platform data where specifying all three separately was explicitly
allowed. Have you verified that this doesn't cause any regressions?

Thierry

Eric Bénard Oct. 24, 2013, 3:26 p.m. UTC | #2

Hi Thierry,

Le Thu, 24 Oct 2013 17:17:37 +0200,
Thierry Reding <[e-mail]> a écrit :
> > +- ti,max-rt: maximum pressure.
> > +- ti,fuzzy: specifies the absolute input fuzz value.
> > +  If set, it will permit noise in the data up to +- the value given to the fuzz
> > +  parameter, that is used to filter noise from the event stream.
> 
> Any reason why these can't be specified per axis? From my experience
> with this chip it can make sense to use different values for the
> different axes. Well, perhaps X and Y axes can share one fuzz factor,
> but the Z axis is sometimes different.
> 
> You also modify the driver to ignore the X and Z axes fuzz factor even
> for platform data where specifying all three separately was explicitly
> allowed. Have you verified that this doesn't cause any regressions?
> 
That was not intended, that's an error, we will fix that.

Thanks,
Eric

Lothar Waßmann Oct. 25, 2013, 5:56 a.m. UTC | #3

Hi,

Grant Likely wrote:
> On Thu, 24 Oct 2013 14:42:13 +0200, Denis Carikli <[e-mail]> wrote:
> > Cc: Rob Herring <[e-mail]>
> > Cc: Pawel Moll <[e-mail]>
> > Cc: Mark Rutland <[e-mail]>
> > Cc: Stephen Warren <[e-mail]>
> > Cc: Ian Campbell <[e-mail]>
> > Cc: [e-mail]
> > Cc: Dmitry Torokhov <[e-mail]>
> > Cc: [e-mail]
> > Cc: Sascha Hauer <[e-mail]>
> > Cc: [e-mail]
> > Cc: Lothar Waßmann <[e-mail]>
> > Cc: Eric Bénard <[e-mail]>
> > Signed-off-by: Denis Carikli <[e-mail]>
> > ---
> > ChangeLog v6->v7:
> > - One small whitespace cleanup.
> > - The properties specific to that driver are now prefixed with "ti,".
> > - The ti,fuzzy property has now better documentation.
> > ---
> >  .../bindings/input/touchscreen/tsc2007.txt         |   45 +++++
> >  drivers/input/touchscreen/tsc2007.c                |  194 +++++++++++++++-----
> >  2 files changed, 198 insertions(+), 41 deletions(-)
> >  create mode 100644 Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt b/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt
> > new file mode 100644
> > index 0000000..516b63b
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt
> > @@ -0,0 +1,45 @@
> > +* Texas Instruments tsc2007 touchscreen controller
> > +
> > +Required properties:
> > +- compatible: must be "ti,tsc2007".
> > +- reg: I2C address of the chip.
> > +- ti,x-plate-ohms: X-plate resistance in ohms.
> > +
> > +Optional properties:
> > +- gpios: the interrupt gpio the chip is connected to (trough the penirq pin)
> > +  (see GPIO binding[2] for more details).
> 
> Hmmm, why is this needed? Is the line used for anything other than
> finding the irq number? If it is just an interrupt then an interrupts
> property is all that should be specified.
> 
It's also the pendown detect GPIO. It asserts an interrupt when first
activated and is then polled in the driver until it goes inactive again.


Lothar Waßmann

Lothar Waßmann Oct. 25, 2013, 6:39 a.m. UTC | #4

Hi,

Thierry Reding wrote:
> On Thu, Oct 24, 2013 at 02:42:13PM +0200, Denis Carikli wrote:
> > Cc: Rob Herring <[e-mail]>
> > Cc: Pawel Moll <[e-mail]>
> > Cc: Mark Rutland <[e-mail]>
> > Cc: Stephen Warren <[e-mail]>
> > Cc: Ian Campbell <[e-mail]>
> > Cc: [e-mail]
> > Cc: Dmitry Torokhov <[e-mail]>
> > Cc: [e-mail]
> > Cc: Sascha Hauer <[e-mail]>
> > Cc: [e-mail]
> > Cc: Lothar Waßmann <[e-mail]>
> > Cc: Eric Bénard <[e-mail]>
> > Signed-off-by: Denis Carikli <[e-mail]>
> > ---
> > ChangeLog v6->v7:
> > - One small whitespace cleanup.
> > - The properties specific to that driver are now prefixed with "ti,".
> > - The ti,fuzzy property has now better documentation.
> > ---
> >  .../bindings/input/touchscreen/tsc2007.txt         |   45 +++++
> >  drivers/input/touchscreen/tsc2007.c                |  194 +++++++++++++++-----
> >  2 files changed, 198 insertions(+), 41 deletions(-)
> >  create mode 100644 Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt b/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt
> > new file mode 100644
> > index 0000000..516b63b
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt
> > @@ -0,0 +1,45 @@
> > +* Texas Instruments tsc2007 touchscreen controller
> > +
> > +Required properties:
> > +- compatible: must be "ti,tsc2007".
> > +- reg: I2C address of the chip.
> > +- ti,x-plate-ohms: X-plate resistance in ohms.
> > +
> > +Optional properties:
> > +- gpios: the interrupt gpio the chip is connected to (trough the penirq pin)
> > +  (see GPIO binding[2] for more details).
> > +- interrupt-parent: the phandle for the gpio controller
> > +  (see interrupt binding[1]).
> > +- interrupts: (gpio) interrupt to which the chip is connected
> > +  (see interrupt binding[1]).
> > +- pinctrl-0: Should specify pin control groups used for the gpio
> > +  (see pinctrl bindings[0]).
> > +- pinctrl-names: Should contain only one value - "default"
> > +  (see pinctrl bindings[0]).
> 
> Also I haven't seen a response as to why this can't be handled by the
> GPIO driver. Adding Linus Walleij, perhaps he knows a more definitive
> answer.
> 
> Linus, the issue here is that the pinctrl properties for this chip are
> supposed to pinmux the pendown GPIO for this chip. I was under the
> impression that this should be handled by the GPIO controller itself, so
> that when gpio_request() was called on a pin it would be the GPIO
> controller driver's responsibility to pinmux it appropriately.
> 
When a GPIO is requested the GPIO layer cannot know what it is
requested for and how the pinmux for the pin function should be
configured (pullups, drive strength, ...). A pin may have multiple
functions depending on what modules are plugged into a baseboard.

Thus the pinctrl binding needs to be with the driver that uses the pin.


Lothar Waßmann

Thierry Reding Oct. 25, 2013, 8:33 a.m. UTC | #5

On Fri, Oct 25, 2013 at 08:39:51AM +0200, Lothar Waßmann wrote:
> Hi,
> 
> Thierry Reding wrote:
> > On Thu, Oct 24, 2013 at 02:42:13PM +0200, Denis Carikli wrote:
> > > Cc: Rob Herring <[e-mail]>
> > > Cc: Pawel Moll <[e-mail]>
> > > Cc: Mark Rutland <[e-mail]>
> > > Cc: Stephen Warren <[e-mail]>
> > > Cc: Ian Campbell <[e-mail]>
> > > Cc: [e-mail]
> > > Cc: Dmitry Torokhov <[e-mail]>
> > > Cc: [e-mail]
> > > Cc: Sascha Hauer <[e-mail]>
> > > Cc: [e-mail]
> > > Cc: Lothar Waßmann <[e-mail]>
> > > Cc: Eric Bénard <[e-mail]>
> > > Signed-off-by: Denis Carikli <[e-mail]>
> > > ---
> > > ChangeLog v6->v7:
> > > - One small whitespace cleanup.
> > > - The properties specific to that driver are now prefixed with "ti,".
> > > - The ti,fuzzy property has now better documentation.
> > > ---
> > >  .../bindings/input/touchscreen/tsc2007.txt         |   45 +++++
> > >  drivers/input/touchscreen/tsc2007.c                |  194 +++++++++++++++-----
> > >  2 files changed, 198 insertions(+), 41 deletions(-)
> > >  create mode 100644 Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt
> > > 
> > > diff --git a/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt b/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt
> > > new file mode 100644
> > > index 0000000..516b63b
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt
> > > @@ -0,0 +1,45 @@
> > > +* Texas Instruments tsc2007 touchscreen controller
> > > +
> > > +Required properties:
> > > +- compatible: must be "ti,tsc2007".
> > > +- reg: I2C address of the chip.
> > > +- ti,x-plate-ohms: X-plate resistance in ohms.
> > > +
> > > +Optional properties:
> > > +- gpios: the interrupt gpio the chip is connected to (trough the penirq pin)
> > > +  (see GPIO binding[2] for more details).
> > > +- interrupt-parent: the phandle for the gpio controller
> > > +  (see interrupt binding[1]).
> > > +- interrupts: (gpio) interrupt to which the chip is connected
> > > +  (see interrupt binding[1]).
> > > +- pinctrl-0: Should specify pin control groups used for the gpio
> > > +  (see pinctrl bindings[0]).
> > > +- pinctrl-names: Should contain only one value - "default"
> > > +  (see pinctrl bindings[0]).
> > 
> > Also I haven't seen a response as to why this can't be handled by the
> > GPIO driver. Adding Linus Walleij, perhaps he knows a more definitive
> > answer.
> > 
> > Linus, the issue here is that the pinctrl properties for this chip are
> > supposed to pinmux the pendown GPIO for this chip. I was under the
> > impression that this should be handled by the GPIO controller itself, so
> > that when gpio_request() was called on a pin it would be the GPIO
> > controller driver's responsibility to pinmux it appropriately.
> > 
> When a GPIO is requested the GPIO layer cannot know what it is
> requested for and how the pinmux for the pin function should be
> configured (pullups, drive strength, ...). A pin may have multiple
> functions depending on what modules are plugged into a baseboard.

But GPIO is one specific function of a given pin, isn't it?

> Thus the pinctrl binding needs to be with the driver that uses the pin.

I wonder if this really needs to be dynamically configured depending on
the driver. Properties like pullups and driver strength can potentially
harm hardware when they're wrong, so relying on the driver's probe to
configure them correctly doesn't sound very safe. It's always possible
to disable the device (either via modifying the DTS or by having the
bootloader patch it). That means the driver won't be probed at all, and
therefore none of the pinctrl or pinmux settings will be applied.

Thierry

Linus Walleij Nov. 4, 2013, 12:01 p.m. UTC | #6

On Thu, Oct 24, 2013 at 5:17 PM, Thierry Reding
<[e-mail]> wrote:
> On Thu, Oct 24, 2013 at 02:42:13PM +0200, Denis Carikli wrote:

>> +Optional properties:
>> +- gpios: the interrupt gpio the chip is connected to (trough the penirq pin)
>> +  (see GPIO binding[2] for more details).
>> +- interrupt-parent: the phandle for the gpio controller
>> +  (see interrupt binding[1]).
>> +- interrupts: (gpio) interrupt to which the chip is connected
>> +  (see interrupt binding[1]).
>> +- pinctrl-0: Should specify pin control groups used for the gpio
>> +  (see pinctrl bindings[0]).
>> +- pinctrl-names: Should contain only one value - "default"
>> +  (see pinctrl bindings[0]).
>
> Also I haven't seen a response as to why this can't be handled by the
> GPIO driver. Adding Linus Walleij, perhaps he knows a more definitive
> answer.
>
> Linus, the issue here is that the pinctrl properties for this chip are
> supposed to pinmux the pendown GPIO for this chip. I was under the
> impression that this should be handled by the GPIO controller itself, so
> that when gpio_request() was called on a pin it would be the GPIO
> controller driver's responsibility to pinmux it appropriately.

If this is the only thing it does (just mux in the GPIO and not setting
any pulls or other pin config properties) then it can fall through from
the GPIO controller's request function to pinctrl_request_gpio()
and then pinctrl_free_gpio(), pinctrl_gpio_direction_input()
and pinctrl_gpio_direction_output() respectively so that pin control
provides a muxing back end to the GPIO driver.

Actually these functions are up to the driver to implement, but
the core will call ->gpio_request_enable() on the pinctrl driver,
and if all GPIOs are set up the same way (i.e. the same bits
are always poked into the hardware) then this can be done
in that routine.

If more fine-grained control is needed, this approach providing
a full pin control handle and state settings connected to the
struct device * can and should be used instead.

Yours,
Linus Walleij

Patch

diff --git a/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt b/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt
new file mode 100644
index 0000000..516b63b
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/touchscreen/tsc2007.txt
@@ -0,0 +1,45 @@ 
+* Texas Instruments tsc2007 touchscreen controller
+
+Required properties:
+- compatible: must be "ti,tsc2007".
+- reg: I2C address of the chip.
+- ti,x-plate-ohms: X-plate resistance in ohms.
+
+Optional properties:
+- gpios: the interrupt gpio the chip is connected to (trough the penirq pin)
+  (see GPIO binding[2] for more details).
+- interrupt-parent: the phandle for the gpio controller
+  (see interrupt binding[1]).
+- interrupts: (gpio) interrupt to which the chip is connected
+  (see interrupt binding[1]).
+- pinctrl-0: Should specify pin control groups used for the gpio
+  (see pinctrl bindings[0]).
+- pinctrl-names: Should contain only one value - "default"
+  (see pinctrl bindings[0]).
+- ti,max-rt: maximum pressure.
+- ti,fuzzy: specifies the absolute input fuzz value.
+  If set, it will permit noise in the data up to +- the value given to the fuzz
+  parameter, that is used to filter noise from the event stream.
+- ti,poll-period: how much time to wait(in millisecond) before reading again the
+  values from the tsc2007.
+
+[0]: Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
+[1]: Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
+[2]: Documentation/devicetree/bindings/gpio/gpio.txt
+
+Example:
+	&i2c1 {
+		/* ... */
+		tsc2007@49 {
+			compatible = "ti,tsc2007";
+			reg = <0x49>;
+			pinctrl-names = "default";
+			pinctrl-0 = <&pinctrl_tsc2007_1>;
+			interrupt-parent = <&gpio4>;
+			interrupts = <0x0 0x8>;
+			gpios = <&gpio4 0 0>;
+			ti,x-plate-ohms = <180>;
+		};
+
+		/* ... */
+	};
diff --git a/drivers/input/touchscreen/tsc2007.c b/drivers/input/touchscreen/tsc2007.c
index 0b67ba4..c50d64e 100644
--- a/drivers/input/touchscreen/tsc2007.c
+++ b/drivers/input/touchscreen/tsc2007.c
@@ -26,6 +26,9 @@ 
 #include <linux/interrupt.h>
 #include <linux/i2c.h>
 #include <linux/i2c/tsc2007.h>
+#include <linux/of_device.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
 
 #define TSC2007_MEASURE_TEMP0		(0x0 << 4)
 #define TSC2007_MEASURE_AUX		(0x2 << 4)
@@ -74,7 +77,10 @@  struct tsc2007 {
 	u16			max_rt;
 	unsigned long		poll_delay;
 	unsigned long		poll_period;
+	int			fuzzy;
+	char			of;
 
+	unsigned		gpio;
 	int			irq;
 
 	wait_queue_head_t	wait;
@@ -84,6 +90,11 @@  struct tsc2007 {
 	void			(*clear_penirq)(void);
 };
 
+static int tsc2007_get_pendown_state_dt(struct tsc2007 *ts)
+{
+	return !gpio_get_value(ts->gpio);
+}
+
 static inline int tsc2007_xfer(struct tsc2007 *tsc, u8 cmd)
 {
 	s32 data;
@@ -142,6 +153,14 @@  static u32 tsc2007_calculate_pressure(struct tsc2007 *tsc, struct ts_event *tc)
 	return rt;
 }
 
+static bool tsc2007_is_pen_down_valid(struct tsc2007 *ts)
+{
+	if (ts->of)
+		return gpio_is_valid(ts->gpio);
+	else
+		return ts->get_pendown_state ? true : false;
+}
+
 static bool tsc2007_is_pen_down(struct tsc2007 *ts)
 {
 	/*
@@ -158,10 +177,13 @@  static bool tsc2007_is_pen_down(struct tsc2007 *ts)
 	 * to fall back on the pressure reading.
 	 */
 
-	if (!ts->get_pendown_state)
+	if (!tsc2007_is_pen_down_valid(ts))
 		return true;
 
-	return ts->get_pendown_state();
+	if (ts->of)
+		return tsc2007_get_pendown_state_dt(ts);
+	else
+		return ts->get_pendown_state();
 }
 
 static irqreturn_t tsc2007_soft_irq(int irq, void *handle)
@@ -178,7 +200,7 @@  static irqreturn_t tsc2007_soft_irq(int irq, void *handle)
 
 		rt = tsc2007_calculate_pressure(ts, &tc);
 
-		if (rt == 0 && !ts->get_pendown_state) {
+		if (!rt && !tsc2007_is_pen_down_valid(ts)) {
 			/*
 			 * If pressure reported is 0 and we don't have
 			 * callback to check pendown state, we have to
@@ -228,7 +250,7 @@  static irqreturn_t tsc2007_hard_irq(int irq, void *handle)
 {
 	struct tsc2007 *ts = handle;
 
-	if (!ts->get_pendown_state || likely(ts->get_pendown_state()))
+	if (tsc2007_is_pen_down(ts))
 		return IRQ_WAKE_THREAD;
 
 	if (ts->clear_penirq)
@@ -273,34 +295,65 @@  static void tsc2007_close(struct input_dev *input_dev)
 	tsc2007_stop(ts);
 }
 
-static int tsc2007_probe(struct i2c_client *client,
-				   const struct i2c_device_id *id)
+#ifdef CONFIG_OF
+static int tsc2007_probe_dt(struct i2c_client *client, struct tsc2007 *ts,
+			    struct device_node *np)
 {
-	struct tsc2007 *ts;
-	struct tsc2007_platform_data *pdata = client->dev.platform_data;
-	struct input_dev *input_dev;
-	int err;
-
-	if (!pdata) {
-		dev_err(&client->dev, "platform data is required!\n");
+	int err = 0;
+	u32 val32;
+	u64 val64;
+
+	if (!of_property_read_u32(np, "ti,max-rt", &val32))
+		ts->max_rt = val32;
+	else
+		ts->max_rt = MAX_12BIT;
+
+	if (!of_property_read_u32(np, "ti,fuzzy", &val32))
+		ts->fuzzy = val32;
+
+	if (!of_property_read_u64(np, "ti,poll-period", &val64))
+		ts->poll_period = val64;
+	else
+		ts->poll_period = 1;
+
+	if (!of_property_read_u32(np, "ti,x-plate-ohms", &val32)) {
+		ts->x_plate_ohms = val32;
+	} else {
+		dev_err(&client->dev,
+			"Error: lacking ti,x-plate-ohms devicetree property. (err %d).",
+			err);
 		return -EINVAL;
 	}
 
-	if (!i2c_check_functionality(client->adapter,
-				     I2C_FUNC_SMBUS_READ_WORD_DATA))
-		return -EIO;
+	ts->gpio = of_get_gpio(np, 0);
+	if (!gpio_is_valid(ts->gpio))
+		dev_err(&client->dev,
+			"GPIO not found (of_get_gpio returned %d)\n",
+			ts->gpio);
 
-	ts = kzalloc(sizeof(struct tsc2007), GFP_KERNEL);
-	input_dev = input_allocate_device();
-	if (!ts || !input_dev) {
-		err = -ENOMEM;
-		goto err_free_mem;
-	}
+	/* Used to detect if it is probed trough the device tree,
+	 * in order to be able to use that information in the IRQ handler.
+	 */
+	ts->of = 1;
 
-	ts->client = client;
-	ts->irq = client->irq;
-	ts->input = input_dev;
-	init_waitqueue_head(&ts->wait);
+	return 0;
+}
+#else
+static int tsc2007_probe_dt(struct i2c_client *client, struct tsc2007 *ts,
+			    struct device_node *np)
+{
+	return -ENODEV;
+}
+#endif
+
+static int tsc2007_probe_pdev(struct i2c_client *client, struct tsc2007 *ts,
+			      struct tsc2007_platform_data *pdata,
+			      const struct i2c_device_id *id)
+{
+	if (!pdata) {
+		dev_err(&client->dev, "platform data is required!\n");
+		return -EINVAL;
+	}
 
 	ts->model             = pdata->model;
 	ts->x_plate_ohms      = pdata->x_plate_ohms;
@@ -309,13 +362,57 @@  static int tsc2007_probe(struct i2c_client *client,
 	ts->poll_period       = pdata->poll_period ? : 1;
 	ts->get_pendown_state = pdata->get_pendown_state;
 	ts->clear_penirq      = pdata->clear_penirq;
+	ts->fuzzy             = pdata->fuzzy;
 
 	if (pdata->x_plate_ohms == 0) {
 		dev_err(&client->dev, "x_plate_ohms is not set up in platform data");
-		err = -EINVAL;
-		goto err_free_mem;
+		return -EINVAL;
 	}
 
+	/* Used to detect if it is probed trough the device tree,
+	 * in order to be able to use that information in the IRQ handler.
+	 */
+	ts->of = 0;
+
+	return 0;
+}
+
+static int tsc2007_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct device_node *np = client->dev.of_node;
+	struct tsc2007_platform_data *pdata = client->dev.platform_data;
+	struct tsc2007 *ts;
+	struct input_dev *input_dev;
+	int err = 0;
+
+	ts = devm_kzalloc(&client->dev, sizeof(struct tsc2007), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	if (np)
+		err = tsc2007_probe_dt(client, ts, np);
+	else
+		err = tsc2007_probe_pdev(client, ts, pdata, id);
+
+	if (err)
+		return err;
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_READ_WORD_DATA))
+		return -EIO;
+
+	input_dev = input_allocate_device();
+	if (!input_dev) {
+		err = -ENOMEM;
+		goto err_free_input;
+	};
+
+	ts->client = client;
+	ts->irq = client->irq;
+	ts->input = input_dev;
+	init_waitqueue_head(&ts->wait);
+
 	snprintf(ts->phys, sizeof(ts->phys),
 		 "%s/input0", dev_name(&client->dev));
 
@@ -331,19 +428,21 @@  static int tsc2007_probe(struct i2c_client *client,
 	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
 	input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
 
-	input_set_abs_params(input_dev, ABS_X, 0, MAX_12BIT, pdata->fuzzx, 0);
-	input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, pdata->fuzzy, 0);
+	input_set_abs_params(input_dev, ABS_X, 0, MAX_12BIT, ts->fuzzy, 0);
+	input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, ts->fuzzy, 0);
 	input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT,
-			pdata->fuzzz, 0);
+			     ts->fuzzy, 0);
 
-	if (pdata->init_platform_hw)
-		pdata->init_platform_hw();
+	if (!np) {
+		if (pdata->init_platform_hw)
+			pdata->init_platform_hw();
+	}
 
 	err = request_threaded_irq(ts->irq, tsc2007_hard_irq, tsc2007_soft_irq,
 				   IRQF_ONESHOT, client->dev.driver->name, ts);
 	if (err < 0) {
 		dev_err(&client->dev, "irq %d busy?\n", ts->irq);
-		goto err_free_mem;
+		goto err_free_input;
 	}
 
 	tsc2007_stop(ts);
@@ -358,23 +457,27 @@  static int tsc2007_probe(struct i2c_client *client,
 
  err_free_irq:
 	free_irq(ts->irq, ts);
-	if (pdata->exit_platform_hw)
-		pdata->exit_platform_hw();
- err_free_mem:
+	if (!np) {
+		if (pdata->exit_platform_hw)
+			pdata->exit_platform_hw();
+	}
+ err_free_input:
 	input_free_device(input_dev);
-	kfree(ts);
 	return err;
 }
 
 static int tsc2007_remove(struct i2c_client *client)
 {
+	struct device_node *np = client->dev.of_node;
 	struct tsc2007	*ts = i2c_get_clientdata(client);
 	struct tsc2007_platform_data *pdata = client->dev.platform_data;
 
 	free_irq(ts->irq, ts);
 
-	if (pdata->exit_platform_hw)
-		pdata->exit_platform_hw();
+	if (!np) {
+		if (pdata->exit_platform_hw)
+			pdata->exit_platform_hw();
+	}
 
 	input_unregister_device(ts->input);
 	kfree(ts);
@@ -389,10 +492,19 @@  static const struct i2c_device_id tsc2007_idtable[] = {
 
 MODULE_DEVICE_TABLE(i2c, tsc2007_idtable);
 
+#ifdef CONFIG_OF
+static const struct of_device_id tsc2007_of_match[] = {
+	{ .compatible = "ti,tsc2007" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, tsc2007_of_match);
+#endif
+
 static struct i2c_driver tsc2007_driver = {
 	.driver = {
 		.owner	= THIS_MODULE,
-		.name	= "tsc2007"
+		.name	= "tsc2007",
+		.of_match_table = of_match_ptr(tsc2007_of_match),
 	},
 	.id_table	= tsc2007_idtable,
 	.probe		= tsc2007_probe,