On 29.01.2018 10:40, Maxime Ripard wrote:

On Mon, Jan 29, 2018 at 12:29:10AM +0100, Philipp Rossak wrote:

quoted

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;

I think you should add some documentation along with all the fields
you're adding.

ok I will add more informations in the next version into the commit message.

quoted

  };
  
  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,

That's already its value if you leave it out.

quoted

  };
  
  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];

Why do you have two different values here?

I think my idea was too complex! I thought it would be better to check 
if calibration data was read, and is able to be written to hardware. 
those information were split per register.

I think a u64 should be fine for calibration_data. When I write the 
calibration data I can check on the sensor count and write only the 
lower 32 bits if there are less than 3 sensors.

Is this ok for you?

quoted

  	/* 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;

goto considered evil ? :)

this was a suggestion from Jonatan in version one, to make the code 
better readable.
.

quoted

+	}
+
+	cell_data = (u64 *)nvmem_cell_read(cell, &cell_size);
+	nvmem_cell_put(cell);
+	switch (cell_size) {
+		case 8:
+		case 6:
+			info->has_calibration_data[1] = true;
+			info->calibration_data[1] = be32_to_cpu(
+					upper_32_bits(cell_data[0]));
+		case 4:
+		case 2:
+			info->has_calibration_data[0] = true;
+			info->calibration_data[0] = be32_to_cpu(
+					lower_32_bits(cell_data[0]));

Why do you need that switch?

You are right! The calibration reg seems to be always 64 bit wide. [1]
So I will just check for the length of 8.

Thanks!
Maxime

[1]: http://linux-sunxi.org/SID_Register_Guide#eFUSE

Thanks,
Philipp