linux-kernel - Re: [PATCH v2 06/16] iio: adc: sun4i-gpadc-iio: rework: support multiple sensors

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Message-ID: <20180131184236.4yhp732l5kenhmp2@qschulz>
Date:   Wed, 31 Jan 2018 19:42:36 +0100
From:   Quentin Schulz <quentin.schulz@...e-electrons.com>
To:     Philipp Rossak <embed3d@...il.com>
Cc:     lee.jones@...aro.org, robh+dt@...nel.org, mark.rutland@....com,
        maxime.ripard@...e-electrons.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,
        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 06/16] iio: adc: sun4i-gpadc-iio: rework: support
 multiple sensors

Hi Philipp,

On Mon, Jan 29, 2018 at 12:29:09AM +0100, Philipp Rossak wrote:
> For adding newer sensor some basic rework of the code is necessary.
> 
> This patch reworks the driver to be able to handle more than one
> thermal sensor. Newer SoC like the A80 have 4 thermal sensors.
> Because of this the maximal sensor count value was set to 4.
> 
> The sensor_id value is set during sensor registration and is for each
> registered sensor indiviual. This makes it able to differntiate the
> sensors when the value is read from the register.
> 
> In function sun4i_gpadc_read_raw(), the sensor number of the ths sensor
> was directly set to 0 (sun4i_gpadc_temp_read(x,x,0)). This selects
> in the temp_read function automatically sensor 0. A check for the
> sensor_id is here not required since the old sensors only have one
> thermal sensor. In addition to that is the sun4i_gpadc_read_raw()
> function only used by the "older" sensors (before A33) where the
> thermal sensor was a cobination of an adc and a thermal sensor.
> 
> Signed-off-by: Philipp Rossak <embed3d@...il.com>
> ---
>  drivers/iio/adc/sun4i-gpadc-iio.c | 36 +++++++++++++++++++++++-------------
>  include/linux/mfd/sun4i-gpadc.h   |  3 +++
>  2 files changed, 26 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/iio/adc/sun4i-gpadc-iio.c b/drivers/iio/adc/sun4i-gpadc-iio.c
> index 51ec0104d678..ac9ad2f8232f 100644
> --- a/drivers/iio/adc/sun4i-gpadc-iio.c
> +++ b/drivers/iio/adc/sun4i-gpadc-iio.c
> @@ -67,12 +67,13 @@ struct gpadc_data {
>  	unsigned int	tp_adc_select;
>  	unsigned int	(*adc_chan_select)(unsigned int chan);
>  	unsigned int	adc_chan_mask;
> -	unsigned int	temp_data;
> +	unsigned int	temp_data[MAX_SENSOR_COUNT];
>  	int		(*sample_start)(struct sun4i_gpadc_iio *info);
>  	int		(*sample_end)(struct sun4i_gpadc_iio *info);
>  	bool		has_bus_clk;
>  	bool		has_bus_rst;
>  	bool		has_mod_clk;
> +	int		sensor_count;
>  };
>  

I've noticed that for H3, A83T, A64 (at least), if DATA reg of sensor 0
is e.g. 0x80, DATA reg of sensor N is at 0x80 + 0x04 * N.

Is that verified for other SoCs? Does anyone have some input on this?

We could then just use temp_data as the DATA reg "base" and increment by
0x4 depending on the sensor id instead of using a fixed-size array.

>  static const struct gpadc_data sun4i_gpadc_data = {
> @@ -82,9 +83,10 @@ static const struct gpadc_data sun4i_gpadc_data = {
>  	.tp_adc_select = SUN4I_GPADC_CTRL1_TP_ADC_SELECT,
>  	.adc_chan_select = &sun4i_gpadc_chan_select,
>  	.adc_chan_mask = SUN4I_GPADC_CTRL1_ADC_CHAN_MASK,
> -	.temp_data = SUN4I_GPADC_TEMP_DATA,
> +	.temp_data = {SUN4I_GPADC_TEMP_DATA, 0, 0, 0},
>  	.sample_start = sun4i_gpadc_sample_start,
>  	.sample_end = sun4i_gpadc_sample_end,
> +	.sensor_count = 1,

If the solution above is not desirable/possible, could we use something
like:

unsigned int sun4i_temp_data[] = {SUN4I_GPADC_TEMP_DATA,};

static const struct gpadc_data sun4i_gpadc_data = {
	.temp_data = &sun4i_temp_data,
	.sensor_count = ARRAY_SIZE(sun4i_temp_data),
};

That avoids 1) inconsistencies between the array size and the array
itself, 2) does not require to pad the array with zeroes.

[...]

> @@ -745,9 +752,12 @@ static int sun4i_gpadc_probe(struct platform_device *pdev)
>  	pm_runtime_enable(&pdev->dev);
>  
>  	if (IS_ENABLED(CONFIG_THERMAL_OF)) {
> -		info->tzd = thermal_zone_of_sensor_register(info->sensor_device,
> -							    0, info,
> -							    &sun4i_ts_tz_ops);
> +		for (i = 0; i < info->data->sensor_count; i++) {
> +			info->sensor_id = i;
> +			info->tzd = thermal_zone_of_sensor_register(
> +					info->sensor_device,
> +					i, info, &sun4i_ts_tz_ops);
> +		}

As Maxime said, this does not work.

One way would be to have a new structure being:
struct sun4i_sensor_info {
	struct sun4i_gpadc_iio	*info;
	unsigned int		sensor_id;
};

Or since we only use the iio_dev within the sun4i_gpadc_iio in the
.get_temp function, we may replace info by struct iio_dev *indio_dev
above.

Quentin

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