[PATCH 4/5] Input: tsc2007 - do not register input device without IRQ

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

The driver has no polled input mode and only reports touchscreen input
events from its threaded interrupt handler. When no interrupt is wired,
the device is used solely as an IIO ADC, so registering an input device
serves no purpose and creates a non-functional input node.

Only allocate, configure, and register the input device when an
interrupt is present. This also allows removing the unnecessary
ts->irq checks in the open and stop callbacks.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/input/touchscreen/tsc2007_core.c | 95 +++++++++++++-----------
 1 file changed, 51 insertions(+), 44 deletions(-)

diff --git a/drivers/input/touchscreen/tsc2007_core.c b/drivers/input/touchscreen/tsc2007_core.c
index 8197ad91ed8b..1fb2c26189ba 100644
--- a/drivers/input/touchscreen/tsc2007_core.c
+++ b/drivers/input/touchscreen/tsc2007_core.c
@@ -172,8 +172,7 @@ static void tsc2007_stop(struct tsc2007 *ts)
 	ts->stopped = true;
 	wake_up(&ts->wait);
 
-	if (ts->irq)
-		disable_irq(ts->irq);
+	disable_irq(ts->irq);
 }
 
 static int tsc2007_open(struct input_dev *input_dev)
@@ -182,9 +181,7 @@ static int tsc2007_open(struct input_dev *input_dev)
 	int err;
 
 	ts->stopped = false;
-
-	if (ts->irq)
-		enable_irq(ts->irq);
+	enable_irq(ts->irq);
 
 	/* Prepare for touch readings - power down ADC and enable PENIRQ */
 	err = tsc2007_xfer(ts, PWRDOWN);
@@ -243,37 +240,19 @@ static int tsc2007_probe_properties(struct device *dev, struct tsc2007 *ts)
 	return 0;
 }
 
-static int tsc2007_probe(struct i2c_client *client)
+static int tsc2007_input_configure(struct tsc2007 *ts)
 {
-	struct tsc2007 *ts;
+	struct device *dev = &ts->client->dev;
 	struct input_dev *input_dev;
 	int err;
 
-	if (!i2c_check_functionality(client->adapter,
-				     I2C_FUNC_SMBUS_READ_WORD_DATA))
-		return -EIO;
-
-	ts = devm_kzalloc_obj(&client->dev, struct tsc2007);
-	if (!ts)
-		return -ENOMEM;
-
-	err = tsc2007_probe_properties(&client->dev, ts);
-	if (err)
-		return err;
-
-	input_dev = devm_input_allocate_device(&client->dev);
+	input_dev = devm_input_allocate_device(dev);
 	if (!input_dev)
 		return -ENOMEM;
 
-	ts->client = client;
-	ts->irq = client->irq;
 	ts->input = input_dev;
 
-	init_waitqueue_head(&ts->wait);
-	mutex_init(&ts->mlock);
-
-	snprintf(ts->phys, sizeof(ts->phys),
-		 "%s/input0", dev_name(&client->dev));
+	snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(dev));
 
 	input_dev->name = "TSC2007 Touchscreen";
 	input_dev->phys = ts->phys;
@@ -291,20 +270,49 @@ static int tsc2007_probe(struct i2c_client *client)
 	input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT,
 			     ts->fuzzz, 0);
 
-	if (ts->irq) {
-		err = devm_request_threaded_irq(&client->dev, ts->irq,
-						NULL, tsc2007_soft_irq,
-						IRQF_ONESHOT,
-						client->dev.driver->name, ts);
-		if (err) {
-			dev_err(&client->dev, "Failed to request irq %d: %d\n",
-				ts->irq, err);
-			return err;
-		}
+	err = devm_request_threaded_irq(dev, ts->irq,
+					NULL, tsc2007_soft_irq,
+					IRQF_ONESHOT,
+					dev->driver->name, ts);
+	if (err) {
+		dev_err(dev, "Failed to request irq %d: %d\n", ts->irq, err);
+		return err;
+	}
 
-		tsc2007_stop(ts);
+	tsc2007_stop(ts);
+
+	err = input_register_device(input_dev);
+	if (err) {
+		dev_err(dev, "Failed to register input device: %d\n", err);
+		return err;
 	}
 
+	return 0;
+}
+
+static int tsc2007_probe(struct i2c_client *client)
+{
+	struct tsc2007 *ts;
+	int err;
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_READ_WORD_DATA))
+		return -EIO;
+
+	ts = devm_kzalloc_obj(&client->dev, struct tsc2007);
+	if (!ts)
+		return -ENOMEM;
+
+	ts->client = client;
+	ts->irq = client->irq;
+
+	init_waitqueue_head(&ts->wait);
+	mutex_init(&ts->mlock);
+
+	err = tsc2007_probe_properties(&client->dev, ts);
+	if (err)
+		return err;
+
 	/* power down the chip (TSC2007_SETUP does not ACK on I2C) */
 	err = tsc2007_xfer(ts, PWRDOWN);
 	if (err < 0) {
@@ -313,14 +321,13 @@ static int tsc2007_probe(struct i2c_client *client)
 		return err;	/* chip does not respond */
 	}
 
-	err = input_register_device(input_dev);
-	if (err) {
-		dev_err(&client->dev,
-			"Failed to register input device: %d\n", err);
-		return err;
+	if (ts->irq) {
+		err = tsc2007_input_configure(ts);
+		if (err)
+			return err;
 	}
 
-	err =  tsc2007_iio_configure(ts);
+	err = tsc2007_iio_configure(ts);
 	if (err) {
 		dev_err(&client->dev,
 			"Failed to register with IIO: %d\n", err);
-- 
2.56.0.567.gdb80ae8cd5-goog