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SubjectRe: [PATCH v2 07/16] iio: adc: sun4i-gpadc-iio: rework: support nvmem calibration data
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On 29.01.2018 10:40, Maxime Ripard wrote:
> On Mon, Jan 29, 2018 at 12:29:10AM +0100, Philipp Rossak wrote:
>> 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 <embed3d@gmail.com>
>> ---
>> 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.

>
>> };
>>
>> 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.
>
>> };
>>
>> 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?


>> /* 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.
.
>> + }
>> +
>> + 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

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