iio: potentiometer: mcp4131: use of_device_get_match_data()

Try to get the device's data using OF API. In case of failure, fallback
to the spi_get_device_id() method.
Signed-off-by: Slawomir Stepien <sst@poczta.fm>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/potentiometer/mcp4131.c

@@ -42,6 +42,7 @@
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
+#include <linux/of_device.h>
 #include <linux/spi/spi.h>
 
 #define MCP4131_WRITE		(0x00 << 2)
@@ -243,7 +244,7 @@ static int mcp4131_probe(struct spi_device *spi)
 {
 	int err;
 	struct device *dev = &spi->dev;
-	unsigned long devid = spi_get_device_id(spi)->driver_data;
+	unsigned long devid;
 	struct mcp4131_data *data;
 	struct iio_dev *indio_dev;
 
@@ -254,7 +255,11 @@ static int mcp4131_probe(struct spi_device *spi)
 	data = iio_priv(indio_dev);
 	spi_set_drvdata(spi, indio_dev);
 	data->spi = spi;
-	data->cfg = &mcp4131_cfg[devid];
+	data->cfg = of_device_get_match_data(&spi->dev);
+	if (!data->cfg) {
+		devid = spi_get_device_id(spi)->driver_data;
+		data->cfg = &mcp4131_cfg[devid];
+	}
 
 	mutex_init(&data->lock);
 
@@ -273,7 +278,6 @@ static int mcp4131_probe(struct spi_device *spi)
 	return 0;
 }
 
-#if defined(CONFIG_OF)
 static const struct of_device_id mcp4131_dt_ids[] = {
 	{ .compatible = "microchip,mcp4131-502",
 		.data = &mcp4131_cfg[MCP413x_502] },
@@ -406,7 +410,6 @@ static const struct of_device_id mcp4131_dt_ids[] = {
 	{}
 };
 MODULE_DEVICE_TABLE(of, mcp4131_dt_ids);
-#endif /* CONFIG_OF */
 
 static const struct spi_device_id mcp4131_id[] = {
 	{ "mcp4131-502", MCP413x_502 },