linux-kernel - Re: [PATCH v2 07/16] iio: adc: sun4i-gpadc-iio: rework: support nvmem calibration data

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Message-ID: <20180129094045.sagz2dnzvdadd4yx@flea.lan>
Date:   Mon, 29 Jan 2018 10:40:45 +0100
From:   Maxime Ripard <maxime.ripard@...e-electrons.com>
To:     Philipp Rossak <embed3d@...il.com>
Cc:     lee.jones@...aro.org, robh+dt@...nel.org, mark.rutland@....com,
        wens@...e.org, linux@...linux.org.uk, jic23@...nel.org,
        knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
        davem@...emloft.net, hans.verkuil@...co.com, mchehab@...nel.org,
        rask@...melder.dk, clabbe.montjoie@...il.com, sean@...s.org,
        krzk@...nel.org, quentin.schulz@...e-electrons.com,
        icenowy@...c.io, edu.molinas@...il.com, singhalsimran0@...il.com,
        linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-sunxi@...glegroups.com
Subject: Re: [PATCH v2 07/16] iio: adc: sun4i-gpadc-iio: rework: support
 nvmem calibration data

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@...il.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.

>  };
>  
>  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?

>  	/* 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 ? :)

> +	}
> +
> +	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?

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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