staging: iio: ad7606: implement IIO_CHAN_INFO_OVERSAMPLING_RATIO

This driver predates the availability of IIO_CHAN_INFO_OVERSAMPLING_RATIO
attribute wherein usage has some advantages like it can be accessed by
in-kernel consumers as well as reduces the code size.

Therefore, use IIO_CHAN_INFO_OVERSAMPLING_RATIO to implement the
oversampling_ratio attribute instead of using IIO_DEVICE_ATTR() macro.

Move code from the functions associated with IIO_DEVICE_ATTR() into
the read_raw hook as well as add the write_raw hook with both masks set
to IIO_CHAN_INFO_OVERSAMPLING_RATIO.
Signed-off-by: Eva Rachel Retuya <eraretuya@gmail.com>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/adc/ad7606_core.c

@@ -103,6 +103,9 @@ static int ad7606_read_raw(struct iio_dev *indio_dev,
 		*val = st->range * 2;
 		*val2 = st->chip_info->channels[0].scan_type.realbits;
 		return IIO_VAL_FRACTIONAL_LOG2;
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		*val = st->oversampling;
+		return IIO_VAL_INT;
 	}
 	return -EINVAL;
 }
@@ -145,16 +148,6 @@ static IIO_DEVICE_ATTR(in_voltage_range, S_IRUGO | S_IWUSR,
 		       ad7606_show_range, ad7606_store_range, 0);
 static IIO_CONST_ATTR(in_voltage_range_available, "5000 10000");
 
-static ssize_t ad7606_show_oversampling_ratio(struct device *dev,
-					      struct device_attribute *attr,
-					      char *buf)
-{
-	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
-	struct ad7606_state *st = iio_priv(indio_dev);
-
-	return sprintf(buf, "%u\n", st->oversampling);
-}
-
 static int ad7606_oversampling_get_index(unsigned int val)
 {
 	unsigned char supported[] = {0, 2, 4, 8, 16, 32, 64};
@@ -167,22 +160,23 @@ static int ad7606_oversampling_get_index(unsigned int val)
 	return -EINVAL;
 }
 
-static ssize_t ad7606_store_oversampling_ratio(struct device *dev,
-					       struct device_attribute *attr,
-					       const char *buf, size_t count)
+static int ad7606_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int val,
+			    int val2,
+			    long mask)
 {
-	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct ad7606_state *st = iio_priv(indio_dev);
-	unsigned long lval;
 	int ret;
 
-	ret = kstrtoul(buf, 10, &lval);
-	if (ret)
-		return ret;
-
-	ret = ad7606_oversampling_get_index(lval);
+	switch (mask) {
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		if (val2)
+			return -EINVAL;
+		ret = ad7606_oversampling_get_index(val);
 		if (ret < 0) {
-		dev_err(dev, "oversampling %lu is not supported\n", lval);
+			dev_err(st->dev, "oversampling %d is not supported\n",
+				val);
 			return ret;
 		}
 
@@ -190,21 +184,19 @@ static ssize_t ad7606_store_oversampling_ratio(struct device *dev,
 		gpio_set_value(st->pdata->gpio_os0, (ret >> 0) & 1);
 		gpio_set_value(st->pdata->gpio_os1, (ret >> 1) & 1);
 		gpio_set_value(st->pdata->gpio_os2, (ret >> 2) & 1);
-	st->oversampling = lval;
+		st->oversampling = val;
 		mutex_unlock(&indio_dev->mlock);
-
-	return count;
+		return 0;
+	default:
+		return -EINVAL;
+	}
 }
 
-static IIO_DEVICE_ATTR(oversampling_ratio, S_IRUGO | S_IWUSR,
-		       ad7606_show_oversampling_ratio,
-		       ad7606_store_oversampling_ratio, 0);
 static IIO_CONST_ATTR(oversampling_ratio_available, "0 2 4 8 16 32 64");
 
 static struct attribute *ad7606_attributes_os_and_range[] = {
 	&iio_dev_attr_in_voltage_range.dev_attr.attr,
 	&iio_const_attr_in_voltage_range_available.dev_attr.attr,
-	&iio_dev_attr_oversampling_ratio.dev_attr.attr,
 	&iio_const_attr_oversampling_ratio_available.dev_attr.attr,
 	NULL,
 };
@@ -214,7 +206,6 @@ static const struct attribute_group ad7606_attribute_group_os_and_range = {
 };
 
 static struct attribute *ad7606_attributes_os[] = {
-	&iio_dev_attr_oversampling_ratio.dev_attr.attr,
 	&iio_const_attr_oversampling_ratio_available.dev_attr.attr,
 	NULL,
 };
@@ -241,6 +232,8 @@ static const struct attribute_group ad7606_attribute_group_range = {
 		.address = num,					\
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),\
+		.info_mask_shared_by_all =			\
+			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),	\
 		.scan_index = num,				\
 		.scan_type = {					\
 			.sign = 's',				\
@@ -429,12 +422,14 @@ static const struct iio_info ad7606_info_no_os_or_range = {
 static const struct iio_info ad7606_info_os_and_range = {
 	.driver_module = THIS_MODULE,
 	.read_raw = &ad7606_read_raw,
+	.write_raw = &ad7606_write_raw,
 	.attrs = &ad7606_attribute_group_os_and_range,
 };
 
 static const struct iio_info ad7606_info_os = {
 	.driver_module = THIS_MODULE,
 	.read_raw = &ad7606_read_raw,
+	.write_raw = &ad7606_write_raw,
 	.attrs = &ad7606_attribute_group_os,
 };