Input: ads7846 - do not allow altering platform data

Tested-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/touchscreen/ads7846.c

@@ -881,9 +881,10 @@ static int __devinit ads7846_probe(struct spi_device *spi)
 	struct ads7846 *ts;
 	struct ads7846_packet *packet;
 	struct input_dev *input_dev;
-	struct ads7846_platform_data	*pdata = spi->dev.platform_data;
+	const struct ads7846_platform_data *pdata = spi->dev.platform_data;
 	struct spi_message *m;
 	struct spi_transfer *x;
+	unsigned long irq_flags;
 	int vref;
 	int err;
 
@@ -1174,21 +1175,23 @@ static int __devinit ads7846_probe(struct spi_device *spi)
 		goto err_put_regulator;
 	}
 
-	if (!pdata->irq_flags)
-		pdata->irq_flags = IRQF_TRIGGER_FALLING;
+	irq_flags = pdata->irq_flags ? : IRQF_TRIGGER_FALLING;
+
+	err = request_irq(spi->irq, ads7846_irq, irq_flags,
+			  spi->dev.driver->name, ts);
 
-	if (request_irq(spi->irq, ads7846_irq, pdata->irq_flags,
-			spi->dev.driver->name, ts)) {
+	if (err && !pdata->irq_flags) {
 		dev_info(&spi->dev,
 			"trying pin change workaround on irq %d\n", spi->irq);
 		err = request_irq(spi->irq, ads7846_irq,
 				  IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,
 				  spi->dev.driver->name, ts);
+	}
+
 	if (err) {
 		dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
 		goto err_disable_regulator;
 	}
-	}
 
 	err = ads784x_hwmon_register(spi, ts);
 	if (err)

include/linux/spi/ads7846.h

@@ -48,7 +48,7 @@ struct ads7846_platform_data {
 					 * state if get_pendown_state == NULL
 					 */
 	int	(*get_pendown_state)(void);
-	int	(*filter_init)	(struct ads7846_platform_data *pdata,
+	int	(*filter_init)	(const struct ads7846_platform_data *pdata,
 				 void **filter_data);
 	int	(*filter)	(void *filter_data, int data_idx, int *val);
 	void	(*filter_cleanup)(void *filter_data);