This patch reworks the driver to support nvmem calibration cells.
The driver checks if the nvmem calibration is supported and reads out
the nvmem.

Signed-off-by: Philipp Rossak <redacted>
---
 drivers/iio/adc/sun4i-gpadc-iio.c | 44 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/drivers/iio/adc/sun4i-gpadc-iio.c b/drivers/iio/adc/sun4i-gpadc-iio.c
index ac9ad2f8232f..74eeb5cd5218 100644
--- a/drivers/iio/adc/sun4i-gpadc-iio.c
+++ b/drivers/iio/adc/sun4i-gpadc-iio.c

@@ -27,6 +27,7 @@
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/module.h>
+#include <linux/nvmem-consumer.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>

@@ -74,6 +75,7 @@ struct gpadc_data {
 	bool		has_bus_rst;
 	bool		has_mod_clk;
 	int		sensor_count;
+	bool		supports_nvmem;

 };
 
 static const struct gpadc_data sun4i_gpadc_data = {

@@ -87,6 +89,7 @@ static const struct gpadc_data sun4i_gpadc_data = {
 	.sample_start = sun4i_gpadc_sample_start,
 	.sample_end = sun4i_gpadc_sample_end,
 	.sensor_count = 1,
+	.supports_nvmem = false,

 };
 
 static const struct gpadc_data sun5i_gpadc_data = {

@@ -100,6 +103,7 @@ static const struct gpadc_data sun5i_gpadc_data = {
 	.sample_start = sun4i_gpadc_sample_start,
 	.sample_end = sun4i_gpadc_sample_end,
 	.sensor_count = 1,
+	.supports_nvmem = false,
 };
 
 static const struct gpadc_data sun6i_gpadc_data = {

@@ -113,6 +117,7 @@ static const struct gpadc_data sun6i_gpadc_data = {
 	.sample_start = sun4i_gpadc_sample_start,
 	.sample_end = sun4i_gpadc_sample_end,
 	.sensor_count = 1,
+	.supports_nvmem = false,
 };
 
 static const struct gpadc_data sun8i_a33_gpadc_data = {

@@ -123,6 +128,7 @@ static const struct gpadc_data sun8i_a33_gpadc_data = {
 	.sample_start = sun4i_gpadc_sample_start,
 	.sample_end = sun4i_gpadc_sample_end,
 	.sensor_count = 1,
+	.supports_nvmem = false,
 };
 
 struct sun4i_gpadc_iio {

@@ -141,6 +147,8 @@ struct sun4i_gpadc_iio {
 	struct clk			*mod_clk;
 	struct reset_control		*reset;
 	int				sensor_id;
+	u32				calibration_data[2];
+	bool				has_calibration_data[2];

 	/* prevents concurrent reads of temperature and ADC */
 	struct mutex			mutex;
 	struct thermal_zone_device	*tzd;

@@ -561,6 +569,9 @@ static int sun4i_gpadc_probe_dt(struct platform_device *pdev,
 	struct resource *mem;
 	void __iomem *base;
 	int ret;
+	struct nvmem_cell *cell;
+	ssize_t cell_size;
+	u64 *cell_data;
 
 	info->data = of_device_get_match_data(&pdev->dev);
 	if (!info->data)

@@ -575,6 +586,39 @@ static int sun4i_gpadc_probe_dt(struct platform_device *pdev,
 	if (IS_ERR(base))
 		return PTR_ERR(base);
 
+	info->has_calibration_data[0] = false;
+	info->has_calibration_data[1] = false;
+
+	if (!info->data->supports_nvmem)
+		goto no_nvmem;
+
+	cell = nvmem_cell_get(&pdev->dev, "calibration");
+	if (IS_ERR(cell)) {
+		if (PTR_ERR(cell) == -EPROBE_DEFER)
+			return PTR_ERR(cell);
+		goto no_nvmem;