[PATCH] ads7846: Pin change interrupt support

[Michael Roth <mroth@nessie.de>]

Some SoC supports only pin change interrupts on GPIO pins
used as irq lines.

The ads7846 core is not affected from the additional irqs
on the rising edge because the code accounts touch bounce
anyway by kicking in a timer and disabling the irq after
the first request and reenabling the irq after a timeout
when there is no longer pen down detected.

Signed-off-by: Michael Roth <mroth@nessie.de>
---
diff -ur linux-2.6.28/drivers/input/touchscreen/ads7846.c linux-2.6.28-work/drivers/input/touchscreen/ads7846.c
--- linux-2.6.28/drivers/input/touchscreen/ads7846.c    2008-12-25 00:26:37.000000000 +0100
+++ linux-2.6.28-work/drivers/input/touchscreen/ads7846.c       2009-01-17 00:40:15.000000000 +0100
@@ -1131,9 +1131,14 @@

        if (request_irq(spi->irq, ads7846_irq, IRQF_TRIGGER_FALLING,
                        spi->dev.driver->name, ts)) {
-               dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
-               err = -EBUSY;
-               goto err_free_gpio;
+               dev_info(&spi->dev, "trying pin change workaround on irq %d\n", spi->irq);
+               if (request_irq(spi->irq, ads7846_irq,
+                               IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,
+                               spi->dev.driver->name, ts)) {
+                       dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
+                       err = -EBUSY;
+                       goto err_free_gpio;
+               }
        }

        err = ads784x_hwmon_register(spi, ts);