Input: tsc2007 - make sure that X plate resistance is specified

Abort driver initialization if X plate resistance was not specified in
platform data as it will cause pressure to be always calculated as 0,
and making userspace ignore touch coordinates.
Signed-off-by: Philip Rakity <prakity@marvell.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/touchscreen/tsc2007.c

@@ -310,6 +310,12 @@ static int __devinit tsc2007_probe(struct i2c_client *client,
 	ts->get_pendown_state = pdata->get_pendown_state;
 	ts->clear_penirq      = pdata->clear_penirq;
 
+	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;
+	}
+
 	snprintf(ts->phys, sizeof(ts->phys),
 		 "%s/input0", dev_name(&client->dev));
 

include/linux/i2c/tsc2007.h

@@ -5,7 +5,7 @@
 
 struct tsc2007_platform_data {
 	u16	model;				/* 2007. */
-	u16	x_plate_ohms;
+	u16	x_plate_ohms;	/* must be non-zero value */
 	u16	max_rt; /* max. resistance above which samples are ignored */
 	unsigned long poll_delay; /* delay (in ms) after pen-down event
 				     before polling starts */