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

[Philipp Rossak]

On 31.01.2018 19:42, Quentin Schulz wrote:
> 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@xxxxxxxxx>
> > ---
> >   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.

This sounds like a good idea! I will add this to the next version.

I can verify this with a table, I created during development. I will 
upload it during the weekend here: [1]


> >   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
I will have a closer look on this next week, when I start to work on the 
next version..

Thanks,
Philipp

[1]: http://linux-sunxi.org/Thermal_Sensor