iio: adc: stm32-adc: add support of generic channels binding

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>
Link: https://lore.kernel.org/r/20211014131228.4692-5-olivier.moysan@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index 2f137d14f141e163612b2e3dcc60aa693bac15eb..85d09cbd41ae1acbe365b24ceb6bde3fd4ac30d1 100644 (file)
--- 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;