Merge tag 'iio-fixes-for-3.19a' of git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into staging-linus

Jonathan writes:

First round of IIO fixes for the 3.19 cycle.

* ad799x fix ad7991/ad7995/ad7999 setup as they do not have a configuration
  register to write to.  It is written during the convesion sequence. As
  such we don't want to write to it at other times.
* Fix iio_channel_read utility function to return to ensure it is apparent
  if the relevant element is not there. This avoids using a wrong value
  if some channels have the element and others do not.

2 files changed, 16 insertions, 2 deletions

diff --git a/drivers/iio/adc/ad799x.c b/drivers/iio/adc/ad799x.c
index e37412da15f5..b99de00e57b8 100644
--- a/drivers/iio/adc/ad799x.c
+++ b/drivers/iio/adc/ad799x.c
@@ -143,9 +143,15 @@ static int ad799x_write_config(struct ad799x_state *st, u16 val)
         case ad7998:
                 return i2c_smbus_write_word_swapped(st->client, AD7998_CONF_REG,
                         val);
-        default:
+        case ad7992:
+        case ad7993:
+        case ad7994:
                 return i2c_smbus_write_byte_data(st->client, AD7998_CONF_REG,
                         val);
+        default:
+                /* Will be written when doing a conversion */
+                st->config = val;
+                return 0;
         }
 }
 
@@ -155,8 +161,13 @@ static int ad799x_read_config(struct ad799x_state *st)
         case ad7997:
         case ad7998:
                 return i2c_smbus_read_word_swapped(st->client, AD7998_CONF_REG);
-        default:
+        case ad7992:
+        case ad7993:
+        case ad7994:
                 return i2c_smbus_read_byte_data(st->client, AD7998_CONF_REG);
+        default:
+                /* No readback support */
+                return st->config;
         }
 }
 
diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index 866fe904cba2..90c8cb727cc7 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -449,6 +449,9 @@ static int iio_channel_read(struct iio_channel *chan, int *val, int *val2,
         if (val2 == NULL)
                 val2 = &unused;
 
+        if(!iio_channel_has_info(chan->channel, info))
+                return -EINVAL;
+
         if (chan->indio_dev->info->read_raw_multi) {
                 ret = chan->indio_dev->info->read_raw_multi(chan->indio_dev,
                                         chan->channel, INDIO_MAX_RAW_ELEMENTS,