This variable determines how many hardware channels has the chip,
oppositely to the num_channels that can contain more channels, e.g a
timestamp channel in our case. Introducing this variable avoids
decreasing the former num_channels variable when reading the ADC's
channels, and clarifies a bit the code.

Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Signed-off-by: Guillaume Stols <gstols@baylibre.com>
---
 drivers/iio/adc/ad7606.c | 10 +++++++++-
 drivers/iio/adc/ad7606.h |  2 ++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c
index 72e0864ba9e4..34d377e9ac79 100644
--- a/drivers/iio/adc/ad7606.c
+++ b/drivers/iio/adc/ad7606.c
@@ -150,6 +150,7 @@ static int ad7606_16bit_chan_scale_setup(struct ad7606_state *st,
 const struct ad7606_chip_info ad7605_4_info = {
 	.channels = ad7605_channels,
 	.name = "ad7605-4",
+	.num_adc_channels = 4,
 	.num_channels = 5,
 	.scale_setup_cb = ad7606_16bit_chan_scale_setup,
 };
@@ -158,6 +159,7 @@ EXPORT_SYMBOL_NS_GPL(ad7605_4_info, IIO_AD7606);
 const struct ad7606_chip_info ad7606_8_info = {
 	.channels = ad7606_channels_16bit,
 	.name = "ad7606-8",
+	.num_adc_channels = 8,
 	.num_channels = 9,
 	.oversampling_avail = ad7606_oversampling_avail,
 	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
@@ -168,6 +170,7 @@ EXPORT_SYMBOL_NS_GPL(ad7606_8_info, IIO_AD7606);
 const struct ad7606_chip_info ad7606_6_info = {
 	.channels = ad7606_channels_16bit,
 	.name = "ad7606-6",
+	.num_adc_channels = 6,
 	.num_channels = 7,
 	.oversampling_avail = ad7606_oversampling_avail,
 	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
@@ -178,6 +181,7 @@ EXPORT_SYMBOL_NS_GPL(ad7606_6_info, IIO_AD7606);
 const struct ad7606_chip_info ad7606_4_info = {
 	.channels = ad7606_channels_16bit,
 	.name = "ad7606-4",
+	.num_adc_channels = 4,
 	.num_channels = 5,
 	.oversampling_avail = ad7606_oversampling_avail,
 	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
@@ -188,6 +192,7 @@ EXPORT_SYMBOL_NS_GPL(ad7606_4_info, IIO_AD7606);
 const struct ad7606_chip_info ad7606b_info = {
 	.channels = ad7606_channels_16bit,
 	.name = "ad7606b",
+	.num_adc_channels = 8,
 	.num_channels = 9,
 	.oversampling_avail = ad7606_oversampling_avail,
 	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
@@ -198,6 +203,7 @@ EXPORT_SYMBOL_NS_GPL(ad7606b_info, IIO_AD7606);
 const struct ad7606_chip_info ad7606c_16_info = {
 	.channels = ad7606_channels_16bit,
 	.name = "ad7606c16",
+	.num_adc_channels = 8,
 	.num_channels = 9,
 	.oversampling_avail = ad7606_oversampling_avail,
 	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
@@ -208,6 +214,7 @@ EXPORT_SYMBOL_NS_GPL(ad7606c_16_info, IIO_AD7606);
 const struct ad7606_chip_info ad7606c_18_info = {
 	.channels = ad7606_channels_18bit,
 	.name = "ad7606c18",
+	.num_adc_channels = 8,
 	.num_channels = 9,
 	.oversampling_avail = ad7606_oversampling_avail,
 	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
@@ -219,6 +226,7 @@ const struct ad7606_chip_info ad7616_info = {
 	.channels = ad7616_channels,
 	.init_delay_ms = 15,
 	.name = "ad7616",
+	.num_adc_channels = 16,
 	.num_channels = 17,
 	.oversampling_avail = ad7616_oversampling_avail,
 	.oversampling_num = ARRAY_SIZE(ad7616_oversampling_avail),
@@ -519,7 +527,7 @@ static int ad7606_set_sampling_freq(struct ad7606_state *st, unsigned long freq)
 
 static int ad7606_read_samples(struct ad7606_state *st)
 {
-	unsigned int num = st->chip_info->num_channels - 1;
+	unsigned int num = st->chip_info->num_adc_channels;
 
 	return st->bops->read_block(st->dev, num, &st->data);
 }
diff --git a/drivers/iio/adc/ad7606.h b/drivers/iio/adc/ad7606.h
index d401d3ab37e0..b26a11b2eba1 100644
--- a/drivers/iio/adc/ad7606.h
+++ b/drivers/iio/adc/ad7606.h
@@ -71,6 +71,7 @@ typedef int (*ad7606_scale_setup_cb_t)(struct ad7606_state *st,
  * @channels:		channel specification
  * @name		device name
  * @num_channels:	number of channels
+ * @num_adc_channels	the number of channels the ADC actually inputs.
  * @scale_setup_cb:	callback to setup the scales for each channel
  * @oversampling_avail	pointer to the array which stores the available
  *			oversampling ratios.
@@ -82,6 +83,7 @@ typedef int (*ad7606_scale_setup_cb_t)(struct ad7606_state *st,
 struct ad7606_chip_info {
 	const struct iio_chan_spec	*channels;
 	const char			*name;
+	unsigned int			num_adc_channels;
 	unsigned int			num_channels;
 	ad7606_scale_setup_cb_t		scale_setup_cb;
 	const unsigned int		*oversampling_avail;

-- 
2.34.1