NXP: MLK-11476 iio: adc: Enable i.MX6SX adc driver.

Enable i.MX6SX adc driver. ADC driver will try getting ADC controller
channel number via device tree, because i.MX chip enable 4 channels
on each controller.

Signed-off-by: Luwei Zhou <[email protected]>
Signed-off-by: Fugang Duan <[email protected]>
(cherry picked from commit 9a1c0b13424b1c8f2cddbe863cdcdc04ecd6a822)

Using this patch to provide a number of channel limitation if the
supported channel number is smaller than the maximum channel number.

Signed-off-by: Stefan Riedmueller <[email protected]>
Signed-off-by: Christoph Fritz <[email protected]>
Signed-off-by: Christian Hemp <[email protected]>
Signed-off-by: Jan Remmet <[email protected]>
Signed-off-by: Yunus Bas <[email protected]>
Signed-off-by: Andrej Picej <[email protected]>
Reviewed-by: Yunus Bas <[email protected]>

Author: Luwei Zhou

drivers/iio/adc/vf610_adc.c

@@ -803,6 +803,7 @@ static int vf610_adc_probe(struct platform_device *pdev)
 	struct iio_dev *indio_dev;
 	int irq;
 	int ret;
+	u32 channels;
 
 	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(struct vf610_adc));
 	if (!indio_dev) {
@@ -858,11 +859,16 @@ static int vf610_adc_probe(struct platform_device *pdev)
 
 	init_completion(&info->completion);
 
+	ret  = of_property_read_u32(pdev->dev.of_node,
+					"num-channels", &channels);
+	if (ret)
+		channels = ARRAY_SIZE(vf610_adc_iio_channels);
+
 	indio_dev->name = dev_name(&pdev->dev);
 	indio_dev->info = &vf610_adc_iio_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels = vf610_adc_iio_channels;
-	indio_dev->num_channels = ARRAY_SIZE(vf610_adc_iio_channels);
+	indio_dev->num_channels = (int)channels;
 
 	ret = clk_prepare_enable(info->clk);
 	if (ret) {