[PATCH 3/6] iio: light: max44009: Report the integration time via read_avail()

[Arka Mondal <arka@arkamondal.net>]

The light channel has IIO_CHAN_INFO_INT_TIME in info_mask_separate,
so userspace reads the integration time from
in_illuminance_integration_time. The values it accepts are listed by
a custom attribute called illuminance_integration_time_available.
That name lacks the in_ prefix the core puts on the attribute it
describes, so it is registered at the device level, and userspace
looking for in_illuminance_integration_time_available finds nothing.

Report the list through read_avail() and drop the custom attribute
along with the string it printed. read_avail() wants the values as
IIO_VAL_INT_PLUS_NANO pairs, while max44009_write_int_time() rounds a
request to the nearest supported value with find_closest_descending()
over a flat table, so the two forms stay as separate tables.

The eight values do not change. The core prints them with nine
decimals, so the attribute now reads 0.800000000 down to 0.006250000
instead of 0.8 down to 0.00625.

Fixes: 6aef699a7d7e ("iio: light: add driver for MAX44009")
Signed-off-by: Arka Mondal <arka@arkamondal.net>
---

Notes:
    Compile tested only; no relevant hardware available.

 drivers/iio/light/max44009.c | 48 ++++++++++++++++++++----------------
 1 file changed, 27 insertions(+), 21 deletions(-)

diff --git a/drivers/iio/light/max44009.c b/drivers/iio/light/max44009.c
index 82b8a806c5fa..c27f0f9ecc44 100644
--- a/drivers/iio/light/max44009.c
+++ b/drivers/iio/light/max44009.c
@@ -66,15 +66,16 @@ static const u32 max44009_int_time_ns_array[] = {
 	6250000,  /* Manual mode only */
 };
 
-static const char max44009_int_time_str[] =
-	"0.8 "
-	"0.4 "
-	"0.2 "
-	"0.1 "
-	"0.05 "
-	"0.025 "
-	"0.0125 "
-	"0.00625";
+static const int max44009_int_time_avail[] = {
+	0, 800000000,
+	0, 400000000,
+	0, 200000000,
+	0, 100000000,
+	0, 50000000,
+	0, 25000000,
+	0, 12500000,
+	0, 6250000,
+};
 
 struct max44009_data {
 	struct i2c_client *client;
@@ -101,6 +102,7 @@ static const struct iio_chan_spec max44009_channels[] = {
 		.type = IIO_LIGHT,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
 				      BIT(IIO_CHAN_INFO_INT_TIME),
+		.info_mask_separate_available = BIT(IIO_CHAN_INFO_INT_TIME),
 		.event_spec = max44009_event_spec,
 		.num_event_specs = ARRAY_SIZE(max44009_event_spec),
 	},
@@ -284,17 +286,21 @@ static int max44009_read_raw(struct iio_dev *indio_dev,
 	}
 }
 
-static IIO_CONST_ATTR(illuminance_integration_time_available,
-		      max44009_int_time_str);
-
-static struct attribute *max44009_attributes[] = {
-	&iio_const_attr_illuminance_integration_time_available.dev_attr.attr,
-	NULL,
-};
-
-static const struct attribute_group max44009_attribute_group = {
-	.attrs = max44009_attributes,
-};
+static int max44009_read_avail(struct iio_dev *indio_dev,
+			       struct iio_chan_spec const *chan,
+			       const int **vals, int *type, int *length,
+			       long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_INT_TIME:
+		*vals = max44009_int_time_avail;
+		*type = IIO_VAL_INT_PLUS_NANO;
+		*length = ARRAY_SIZE(max44009_int_time_avail);
+		return IIO_AVAIL_LIST;
+	default:
+		return -EINVAL;
+	}
+}
 
 static int max44009_threshold_byte_from_fraction(int integral, int fractional)
 {
@@ -464,7 +470,7 @@ static const struct iio_info max44009_info = {
 	.read_event_config = max44009_read_event_config,
 	.write_event_value = max44009_write_event_value,
 	.write_event_config = max44009_write_event_config,
-	.attrs = &max44009_attribute_group,
+	.read_avail = max44009_read_avail,
 };
 
 static irqreturn_t max44009_threaded_irq_handler(int irq, void *p)
-- 
2.56.0