[PATCH v4 5/8] iio: adc: ad7606: rework available attributes for SW channels

[Alexandru Ardelean <aardelean@baylibre.com>]

For SW mode, the oversampling and scales attributes are always present.
So, they can be implemented via a 'read_avail' hook in iio_info.

For HW mode, it's a bit tricky, as these attributes get assigned based on
GPIO definitions.

So, for SW mode, we define a separate AD7606_SW_CHANNEL() macro, and use
that for the SW channels.
And 'ad7606_info_os_range_and_debug' can be renamed to
'ad7606_info_sw_mode' as it is only used for SW mode.

For the 'read_avail' hook, we'll need to allocate the SW scales, so that
they are just returned userspace without any extra processing.
The allocation will happen when then ad7606_state struct is allocated.
The oversampling available parameters don't need any extra processing; they
can just be passed back to userspace (as they are).

Signed-off-by: Alexandru Ardelean <aardelean@baylibre.com>
---
 drivers/iio/adc/ad7606.c | 63 ++++++++++++++++++++++++++++++++++++----
 drivers/iio/adc/ad7606.h | 31 +++++++++++++++++---
 2 files changed, 85 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c
index 2554a4a4a9c0..4c3fbb28f790 100644
--- a/drivers/iio/adc/ad7606.c
+++ b/drivers/iio/adc/ad7606.c
@@ -507,6 +507,37 @@ static int ad7606_buffer_predisable(struct iio_dev *indio_dev)
 	return 0;
 }
 
+static int ad7606_read_avail(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     const int **vals, int *type, int *length,
+			     long info)
+{
+	struct ad7606_state *st = iio_priv(indio_dev);
+	struct ad7606_chan_scale *cs;
+	unsigned int ch = 0;
+
+	switch (info) {
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		*vals = st->oversampling_avail;
+		*length = st->num_os_ratios;
+		*type = IIO_VAL_INT;
+
+		return IIO_AVAIL_LIST;
+
+	case IIO_CHAN_INFO_SCALE:
+		if (st->sw_mode_en)
+			ch = chan->address;
+
+		cs = &st->chan_scales[ch];
+		*vals = cs->scale_avail_show;
+		*length = cs->num_scales * 2;
+		*type = IIO_VAL_INT_PLUS_MICRO;
+
+		return IIO_AVAIL_LIST;
+	}
+	return -EINVAL;
+}
+
 static const struct iio_buffer_setup_ops ad7606_buffer_ops = {
 	.postenable = &ad7606_buffer_postenable,
 	.predisable = &ad7606_buffer_predisable,
@@ -524,11 +555,11 @@ static const struct iio_info ad7606_info_os_and_range = {
 	.validate_trigger = &ad7606_validate_trigger,
 };
 
-static const struct iio_info ad7606_info_os_range_and_debug = {
+static const struct iio_info ad7606_info_sw_mode = {
 	.read_raw = &ad7606_read_raw,
 	.write_raw = &ad7606_write_raw,
+	.read_avail = &ad7606_read_avail,
 	.debugfs_reg_access = &ad7606_reg_access,
-	.attrs = &ad7606_attribute_group_os_and_range,
 	.validate_trigger = &ad7606_validate_trigger,
 };
 
@@ -554,7 +585,7 @@ static int ad7606_sw_mode_setup(struct iio_dev *indio_dev)
 {
 	unsigned int num_channels = indio_dev->num_channels - 1;
 	struct ad7606_state *st = iio_priv(indio_dev);
-	int ch;
+	int ret, ch;
 
 	if (!st->bops->sw_mode_config)
 		return 0;
@@ -563,7 +594,7 @@ static int ad7606_sw_mode_setup(struct iio_dev *indio_dev)
 	if (!st->sw_mode_en)
 		return 0;
 
-	indio_dev->info = &ad7606_info_os_range_and_debug;
+	indio_dev->info = &ad7606_info_sw_mode;
 
 	/* Scale of 0.076293 is only available in sw mode */
 	/* After reset, in software mode, ±10 V is set by default */
@@ -575,7 +606,29 @@ static int ad7606_sw_mode_setup(struct iio_dev *indio_dev)
 		cs->range = 2;
 	}
 
-	return st->bops->sw_mode_config(indio_dev);
+	ret = st->bops->sw_mode_config(indio_dev);
+	if (ret)
+		return ret;
+
+	for (ch = 0; ch < num_channels; ch++) {
+		struct ad7606_chan_scale *cs = &st->chan_scales[ch];
+		int i;
+
+		cs = &st->chan_scales[ch];
+
+		if (cs->num_scales * 2 > AD760X_MAX_SCALE_SHOW) {
+			dev_err(st->dev, "Driver error: scale range too big");
+			return -ERANGE;
+		}
+
+		/* Generate a scale_avail list for showing to userspace */
+		for (i = 0; i < cs->num_scales; i++) {
+			cs->scale_avail_show[i * 2] = 0;
+			cs->scale_avail_show[i * 2 + 1] = cs->scale_avail[i];
+		}
+	}
+
+	return 0;
 }
 
 int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
diff --git a/drivers/iio/adc/ad7606.h b/drivers/iio/adc/ad7606.h
index afe6a4030e0e..2113ad460c0f 100644
--- a/drivers/iio/adc/ad7606.h
+++ b/drivers/iio/adc/ad7606.h
@@ -27,6 +27,29 @@
 		},						\
 }
 
+#define AD7606_SW_CHANNEL(num, bits) {				\
+		.type = IIO_VOLTAGE,				\
+		.indexed = 1,					\
+		.channel = num,					\
+		.address = num,					\
+		.info_mask_separate =				\
+			BIT(IIO_CHAN_INFO_RAW) |		\
+			BIT(IIO_CHAN_INFO_SCALE),		\
+		.info_mask_separate_available =			\
+			BIT(IIO_CHAN_INFO_SCALE),		\
+		.info_mask_shared_by_all =			\
+			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),	\
+		.info_mask_shared_by_all_available =		\
+			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),	\
+		.scan_index = num,				\
+		.scan_type = {					\
+			.sign = 's',				\
+			.realbits = (bits),			\
+			.storagebits = (bits),			\
+			.endianness = IIO_CPU,			\
+		},						\
+}
+
 #define AD7605_CHANNEL(num)				\
 	AD760X_CHANNEL(num, BIT(IIO_CHAN_INFO_RAW),	\
 		BIT(IIO_CHAN_INFO_SCALE), 0, 16)
@@ -36,10 +59,6 @@
 		BIT(IIO_CHAN_INFO_SCALE),		\
 		BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), bits)
 
-#define AD7606_SW_CHANNEL(num, bits)	\
-	AD760X_CHANNEL(num, BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),\
-		0, BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), bits)
-
 #define AD7616_CHANNEL(num)	AD7606_SW_CHANNEL(num, 16)
 
 /**
@@ -65,11 +84,15 @@ struct ad7606_chip_info {
 /**
  * struct ad7606_chan_scale - channel scale configuration
  * @scale_avail		pointer to the array which stores the available scales
+ * @scale_avail_show	a duplicate of 'scale_avail' which is readily formatted
+ *			such that it can be read via the 'read_avail' hook
  * @num_scales		number of elements stored in the scale_avail array
  * @range		voltage range selection, selects which scale to apply
  */
 struct ad7606_chan_scale {
+#define AD760X_MAX_SCALE_SHOW		(AD760X_MAX_CHANNELS * 2)
 	const unsigned int		*scale_avail;
+	int				scale_avail_show[AD760X_MAX_SCALE_SHOW];
 	unsigned int			num_scales;
 	unsigned int			range;
 };
-- 
2.46.0