iio: adc: at91-sama5d2_adc: merge buffer & trigger init into a function

This change is mostly cosmetic, but it's also a pre-cursor to the
the change for 'iio_buffer_set_attrs()', where the helper gets updated to
better support multiple IIO buffers for 1 IIO device.

The only functional change is that the error message for the trigger alloc
failure is bound to the parent device vs the IIO device object.

Also, the new at91_adc_buffer_and_trigger_init() function was moved after
the definition of the 'at91_adc_fifo_attributes'.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20200929125949.69934-3-alexandru.ardelean@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/at91-sama5d2_adc.c

@@ -1013,21 +1013,6 @@ static struct iio_trigger *at91_adc_allocate_trigger(struct iio_dev *indio,
 
 	return trig;
 }
-
-static int at91_adc_trigger_init(struct iio_dev *indio)
-{
-	struct at91_adc_state *st = iio_priv(indio);
-
-	st->trig = at91_adc_allocate_trigger(indio, st->selected_trig->name);
-	if (IS_ERR(st->trig)) {
-		dev_err(&indio->dev,
-			"could not allocate trigger\n");
-		return PTR_ERR(st->trig);
-	}
-
-	return 0;
-}
-
 static void at91_adc_trigger_handler_nodma(struct iio_dev *indio_dev,
 					   struct iio_poll_func *pf)
 {
@@ -1155,13 +1140,6 @@ static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
 	return IRQ_HANDLED;
 }
 
-static int at91_adc_buffer_init(struct iio_dev *indio)
-{
-	return devm_iio_triggered_buffer_setup(&indio->dev, indio,
-		&iio_pollfunc_store_time,
-		&at91_adc_trigger_handler, &at91_buffer_setup_ops);
-}
-
 static unsigned at91_adc_startup_time(unsigned startup_time_min,
 				      unsigned adc_clk_khz)
 {
@@ -1691,6 +1669,40 @@ static const struct iio_info at91_adc_info = {
 	.hwfifo_set_watermark = &at91_adc_set_watermark,
 };
 
+static int at91_adc_buffer_and_trigger_init(struct device *dev,
+					    struct iio_dev *indio)
+{
+	struct at91_adc_state *st = iio_priv(indio);
+	int ret;
+
+	ret = devm_iio_triggered_buffer_setup(&indio->dev, indio,
+		&iio_pollfunc_store_time,
+		&at91_adc_trigger_handler, &at91_buffer_setup_ops);
+	if (ret < 0) {
+		dev_err(dev, "couldn't initialize the buffer.\n");
+		return ret;
+	}
+
+	if (!st->selected_trig->hw_trig)
+		return 0;
+
+	iio_buffer_set_attrs(indio->buffer, at91_adc_fifo_attributes);
+
+	st->trig = at91_adc_allocate_trigger(indio, st->selected_trig->name);
+	if (IS_ERR(st->trig)) {
+		dev_err(dev, "could not allocate trigger\n");
+		return PTR_ERR(st->trig);
+	}
+
+	/*
+	 * Initially the iio buffer has a length of 2 and
+	 * a watermark of 1
+	 */
+	st->dma_st.watermark = 1;
+
+	return 0;
+}
+
 static int at91_adc_probe(struct platform_device *pdev)
 {
 	struct iio_dev *indio_dev;
@@ -1826,27 +1838,9 @@ static int at91_adc_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, indio_dev);
 
-	ret = at91_adc_buffer_init(indio_dev);
-	if (ret < 0) {
-		dev_err(&pdev->dev, "couldn't initialize the buffer.\n");
-		goto per_clk_disable_unprepare;
-	}
-
-	if (st->selected_trig->hw_trig) {
-		ret = at91_adc_trigger_init(indio_dev);
-		if (ret < 0) {
-			dev_err(&pdev->dev, "couldn't setup the triggers.\n");
+	ret = at91_adc_buffer_and_trigger_init(&pdev->dev, indio_dev);
+	if (ret < 0)
 		goto per_clk_disable_unprepare;
-		}
-		/*
-		 * Initially the iio buffer has a length of 2 and
-		 * a watermark of 1
-		 */
-		st->dma_st.watermark = 1;
-
-		iio_buffer_set_attrs(indio_dev->buffer,
-				     at91_adc_fifo_attributes);
-	}
 
 	if (dma_coerce_mask_and_coherent(&indio_dev->dev, DMA_BIT_MASK(32)))
 		dev_info(&pdev->dev, "cannot set DMA mask to 32-bit\n");