Define extended attribute so that user may choose rising, falling or both
edges for external trigger sources.
Default to rising edge in case it isn't set.

Signed-off-by: Fabrice Gasnier <fabrice.gasn...@st.com>
---
 drivers/iio/adc/stm32-adc.c | 51 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 50 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index 30708bc..9753c39 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -164,6 +164,7 @@ struct stm32_adc_trig_info {
  * @lock:              spinlock
  * @bufi:              data buffer index
  * @num_conv:          expected number of scan conversions
+ * @exten:             external trigger config (enable/polarity)
  */
 struct stm32_adc {
        struct stm32_adc_common *common;
@@ -175,6 +176,7 @@ struct stm32_adc {
        spinlock_t              lock;           /* interrupt lock */
        int                     bufi;
        int                     num_conv;
+       enum stm32_adc_exten    exten;
 };
 
 /**
@@ -449,7 +451,9 @@ static int stm32_adc_set_trig(struct iio_dev *indio_dev,
 
                /* set trigger source, default to rising edge */
                extsel = ret;
-               exten = STM32_EXTEN_HWTRIG_RISING_EDGE;
+               if (adc->exten == STM32_EXTEN_SWTRIG)
+                       adc->exten = STM32_EXTEN_HWTRIG_RISING_EDGE;
+               exten = adc->exten;
        }
 
        spin_lock_irqsave(&adc->lock, flags);
@@ -463,6 +467,39 @@ static int stm32_adc_set_trig(struct iio_dev *indio_dev,
        return 0;
 }
 
+static int stm32_adc_set_trig_pol(struct iio_dev *indio_dev,
+                                 const struct iio_chan_spec *chan,
+                                 unsigned int type)
+{
+       struct stm32_adc *adc = iio_priv(indio_dev);
+
+       adc->exten = type;
+
+       return 0;
+}
+
+static int stm32_adc_get_trig_pol(struct iio_dev *indio_dev,
+                                 const struct iio_chan_spec *chan)
+{
+       struct stm32_adc *adc = iio_priv(indio_dev);
+
+       return adc->exten;
+}
+
+static const char * const stm32_trig_pol_items[] = {
+       [STM32_EXTEN_SWTRIG] = "swtrig",
+       [STM32_EXTEN_HWTRIG_RISING_EDGE] = "rising-edge",
+       [STM32_EXTEN_HWTRIG_FALLING_EDGE] = "falling-edge",
+       [STM32_EXTEN_HWTRIG_BOTH_EDGES] = "both-edges",
+};
+
+const struct iio_enum stm32_adc_trig_pol = {
+       .items = stm32_trig_pol_items,
+       .num_items = ARRAY_SIZE(stm32_trig_pol_items),
+       .get = stm32_adc_get_trig_pol,
+       .set = stm32_adc_set_trig_pol,
+};
+
 /**
  * stm32_adc_single_conv() - Performs a single conversion
  * @indio_dev: IIO device
@@ -745,6 +782,17 @@ static irqreturn_t stm32_adc_trigger_handler(int irq, void 
*p)
        return IRQ_HANDLED;
 }
 
+static const struct iio_chan_spec_ext_info stm32_adc_ext_info[] = {
+       IIO_ENUM("trigger_pol", IIO_SHARED_BY_ALL, &stm32_adc_trig_pol),
+       {
+               .name = "trigger_pol_available",
+               .shared = IIO_SHARED_BY_ALL,
+               .read = iio_enum_available_read,
+               .private = (uintptr_t)&stm32_adc_trig_pol,
+       },
+       {},
+};
+
 static void stm32_adc_chan_init_one(struct iio_dev *indio_dev,
                                    struct iio_chan_spec *chan,
                                    const struct stm32_adc_chan_spec *channel,
@@ -760,6 +808,7 @@ static void stm32_adc_chan_init_one(struct iio_dev 
*indio_dev,
        chan->scan_type.sign = 'u';
        chan->scan_type.realbits = 12;
        chan->scan_type.storagebits = 16;
+       chan->ext_info = stm32_adc_ext_info;
 }
 
 static int stm32_adc_chan_of_init(struct iio_dev *indio_dev)
-- 
1.9.1

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