[PATCH v5 4/7] iio: adc: stm32-adc: add support of generic channels binding

Olivier Moysan
2021-10-14T13:17:40Z

Add support of generic IIO channel binding:
./devicetree/bindings/iio/adc/adc.yaml
Keep support of st,adc-channels and st,adc-diff-channels
for backward compatibility.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
---
drivers/iio/adc/stm32-adc.c | 95 +++++++++++++++++++++++++++++++++----
1 file changed, 86 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index 2f137d14f141..85d09cbd41ae 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -35,7 +35,7 @@
#define STM32H7_BOOST_CLKRATE 20000000UL

#define STM32_ADC_CH_MAX 20 /* max number of channels */
-#define STM32_ADC_CH_SZ 10 /* max channel name size */
+#define STM32_ADC_CH_SZ 16 /* max channel name size */
#define STM32_ADC_MAX_SQ 16 /* SQ1..SQ16 */
#define STM32_ADC_MAX_SMP 7 /* SMPx range is [0..7] */
#define STM32_ADC_TIMEOUT_US 100000
@@ -1792,6 +1792,73 @@ static int stm32_adc_legacy_chan_init(struct iio_dev *indio_dev,
return scan_index;
}

+static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev,
+ struct stm32_adc *adc,
+ struct iio_chan_spec *channels)
+{
+ struct device_node *node = indio_dev->dev.of_node;
+ const struct stm32_adc_info *adc_info = adc->cfg->adc_info;
+ struct device_node *child;
+ const char *name;
+ int val, scan_index = 0, ret;
+ bool differential;
+ u32 vin[2];
+
+ for_each_available_child_of_node(node, child) {
+ ret = of_property_read_u32(child, "reg", &val);
+ if (ret) {
+ dev_err(&indio_dev->dev, "Missing channel index %d\n", ret);
+ goto err;
+ }
+
+ ret = of_property_read_string(child, "label", &name);
+ /* label is optional */
+ if (!ret) {
+ if (strlen(name) >= STM32_ADC_CH_SZ) {
+ dev_err(&indio_dev->dev, "Label %s exceeds %d characters\n",
+ name, STM32_ADC_CH_SZ);
+ return -EINVAL;
+ }
+ strncpy(adc->chan_name[val], name, STM32_ADC_CH_SZ);
+ } else if (ret != -EINVAL) {
+ dev_err(&indio_dev->dev, "Invalid label %d\n", ret);
+ goto err;
+ }
+
+ if (val >= adc_info->max_channels) {
+ dev_err(&indio_dev->dev, "Invalid channel %d\n", val);
+ ret = -EINVAL;
+ goto err;
+ }
+
+ differential = false;
+ ret = of_property_read_u32_array(child, "diff-channels", vin, 2);
+ /* diff-channels is optional */
+ if (!ret) {
+ differential = true;
+ if (vin[0] != val || vin[1] >= adc_info->max_channels) {
+ dev_err(&indio_dev->dev, "Invalid channel in%d-in%d\n",
+ vin[0], vin[1]);
+ goto err;
+ }
+ } else if (ret != -EINVAL) {
+ dev_err(&indio_dev->dev, "Invalid diff-channels property %d\n", ret);
+ goto err;
+ }
+
+ stm32_adc_chan_init_one(indio_dev, &channels[scan_index], val,
+ vin[1], scan_index, differential);
+ scan_index++;
+ }
+
+ return scan_index;
+
+err:
+ of_node_put(child);
+
+ return ret;
+}
+
static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
{
struct device_node *node = indio_dev->dev.of_node;
@@ -1800,15 +1867,22 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
struct iio_chan_spec *channels;
int scan_index = 0, num_channels = 0, ret, i;
u32 smp = 0;
+ bool legacy = false;

- ret = stm32_adc_get_legacy_chan_count(indio_dev, adc);
- if (ret < 0)
- return ret;
- num_channels = ret;
-
+ num_channels = of_get_available_child_count(node);
+ /* If no channels have been found, fallback to channels legacy properties. */
if (!num_channels) {
- dev_err(&indio_dev->dev, "No channels configured\n");
- return -ENODATA;
+ legacy = true;
+
+ ret = stm32_adc_get_legacy_chan_count(indio_dev, adc);
+ if (!ret) {
+ dev_err(indio_dev->dev.parent, "No channel found\n");
+ return -ENODATA;
+ } else if (ret < 0) {
+ return ret;
+ }
+
+ num_channels = ret;
}

if (num_channels > adc_info->max_channels) {
@@ -1832,7 +1906,10 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
if (!channels)
return -ENOMEM;

- ret = stm32_adc_legacy_chan_init(indio_dev, adc, channels);
+ if (legacy)
+ ret = stm32_adc_legacy_chan_init(indio_dev, adc, channels);
+ else
+ ret = stm32_adc_generic_chan_init(indio_dev, adc, channels);
if (ret < 0)
return ret;
scan_index = ret;