iio: adc: stm32-adc: fix device used to request dma

DMA channel request should use device struct from platform device struct.
Currently it's using iio device struct. But at this stage when probing,
device struct isn't yet registered (e.g. device_register is done in
iio_device_register). Since commit 71723a9 ("dmaengine: Create
symlinks between DMA channels and slaves"), a warning message is printed
as the links in sysfs can't be created, due to device isn't yet registered:
- Cannot create DMA slave symlink
- Cannot create DMA dma:rx symlink

Fix this by using device struct from platform device to request dma chan.

Fixes: 2763ea0 ("iio: adc: stm32: add optional dma support")

Signed-off-by: Fabrice Gasnier <[email protected]>
Cc: <[email protected]>
Signed-off-by: Jonathan Cameron <[email protected]>

Author: Fabrice Gasnier

drivers/iio/adc/stm32-adc.c

@@ -1812,18 +1812,18 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev)
 	return 0;
 }
 
-static int stm32_adc_dma_request(struct iio_dev *indio_dev)
+static int stm32_adc_dma_request(struct device *dev, struct iio_dev *indio_dev)
 {
 	struct stm32_adc *adc = iio_priv(indio_dev);
 	struct dma_slave_config config;
 	int ret;
 
-	adc->dma_chan = dma_request_chan(&indio_dev->dev, "rx");
+	adc->dma_chan = dma_request_chan(dev, "rx");
 	if (IS_ERR(adc->dma_chan)) {
 		ret = PTR_ERR(adc->dma_chan);
 		if (ret != -ENODEV) {
 			if (ret != -EPROBE_DEFER)
-				dev_err(&indio_dev->dev,
+				dev_err(dev,
 					"DMA channel request failed with %d\n",
 					ret);
 			return ret;
@@ -1930,7 +1930,7 @@ static int stm32_adc_probe(struct platform_device *pdev)
 	if (ret < 0)
 		return ret;
 
-	ret = stm32_adc_dma_request(indio_dev);
+	ret = stm32_adc_dma_request(dev, indio_dev);
 	if (ret < 0)
 		return ret;