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    SubjectRe: [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@gmail.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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