Input: ads7846 - add support for AD7843 parts

The AD7873 is almost identical to the ADS7846; the only difference is
related to the Power Management bits PD0 and PD1.  This results in a
slightly different PENIRQ enable behavior.  For the AD7873, VREF should
be turned off during differential measurements.

So, add the AD7873/43 to the list of driver supported devices, and prevent
VREF usage during differential/ratiometric conversion modes.

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index 8b05d8e97543..d187be05955f 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -36,6 +36,7 @@
  * TSC2046 is just newer ads7846 silicon.
  * Support for ads7843 tested on Atmel at91sam926x-EK.
  * Support for ads7845 has only been stubbed in.
+ * Support for Analog Devices AD7873 and AD7843 tested.
  *
  * IRQ handling needs a workaround because of a shortcoming in handling
  * edge triggered IRQs on some platforms like the OMAP1/2. These
@@ -984,6 +985,15 @@ static int __devinit ads7846_probe(struct spi_device *spi)
 
         vref = pdata->keep_vref_on;
 
+        if (ts->model == 7873) {
+                /* The AD7873 is almost identical to the ADS7846
+                 * keep VREF off during differential/ratiometric
+                 * conversion modes
+                 */
+                ts->model = 7846;
+                vref = 0;
+        }
+
         /* set up the transfers to read touchscreen state; this assumes we
          * use formula #2 for pressure, not #3.
          */