Re: [PATCH 09/14] iio: adc: rzg2l_adc: Add support for channel 8

Jonathan Cameron
2024-12-03T20:19:07Z

On Tue, 3 Dec 2024 13:13:09 +0200
Claudiu <claudiu.beznea@tuxon.dev> wrote:

> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>
> The ADC on the Renesas RZ/G3S SoC includes an additional channel (channel
> 8) dedicated to reading temperature values from the Thermal Sensor Unit
> (TSU). There is a direct in-SoC connection between the ADC and TSU IPs.
>
> To read the temperature reported by the TSU, a different sampling rate
> (compared to channels 0-7) must be configured in the ADM3 register.
>
> The rzg2l_adc driver has been updated to support reading the TSU
> temperature.
>
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

> static unsigned int rzg2l_adc_readl(struct rzg2l_adc *adc, u32 reg)
> @@ -161,7 +173,7 @@ static void rzg2l_set_trigger(struct rzg2l_adc *adc)
> rzg2l_adc_writel(adc, RZG2L_ADM(1), reg);
> }
>
> -static int rzg2l_adc_conversion_setup(struct rzg2l_adc *adc, u8 ch)
> +static int rzg2l_adc_conversion_setup(struct rzg2l_adc *adc, u8 ch, enum iio_chan_type type)
> {
> const struct rzg2l_adc_hw_params *hw_params = adc->hw_params;
> u32 reg;
> @@ -177,6 +189,15 @@ static int rzg2l_adc_conversion_setup(struct rzg2l_adc *adc, u8 ch)
> reg |= BIT(ch);
> rzg2l_adc_writel(adc, RZG2L_ADM(2), reg);
>
> + reg = rzg2l_adc_readl(adc, RZG2L_ADM(3));
> + reg &= ~hw_params->adsmp_mask;
> + /*
> + * type could be IIO_VOLTAGE = 0 or IIO_TEMP = 9. Divide to 8 to get
> + * index 0 or 1 depending on the channel type.

That is not particularly nice and potentially a little fragile if we get other device
support in future. Better to match on the type in rzg2l_adc_channels[] possibly wrapped
up in a little utility function bool rzg2l_adc_channels_is_temp(); Then use a
? 1 : 0 to get the offset in default_adsmp[]

> + */
> + reg |= hw_params->default_adsmp[type / 8];
> + rzg2l_adc_writel(adc, RZG2L_ADM(3), reg);
> +
> /*
> * Setup ADINT
> * INTS[31] - Select pulse signal
> @@ -192,7 +213,8 @@ static int rzg2l_adc_conversion_setup(struct rzg2l_adc *adc, u8 ch)
> return 0;
> }
>
>
> + case IIO_CHAN_INFO_PROCESSED:
> + if (chan->type != IIO_TEMP)
> + return -EINVAL;
> +
> + mutex_lock(&adc->lock);
> + ret = rzg2l_adc_conversion(indio_dev, chan->type, adc, ch);
> + if (!ret) {
> + /* Convert it to mili Celsius. */
> + *val = adc->last_val[ch] * 1000;
Prefer you provide a scale of 1000 and report this raw.
> + }
Also strong preference for error conditions out of line.
As in that other case, guard() makes that easier as yo ucan do
{

guard(mutex)(&adc->lock);
ret = rz....
if (ret)
return ret;

*val = ...

return IIO_VAL_INT;
}

> + mutex_unlock(&adc->lock);
> +
> + return ret ? ret : IIO_VAL_INT;
> +
> default:
> return -EINVAL;
> }

> static const struct iio_info rzg2l_adc_iio_info = {
> @@ -332,11 +368,14 @@ static int rzg2l_adc_parse_properties(struct platform_device *pdev, struct rzg2l
> if (channel >= hw_params->num_channels)
> return -EINVAL;
>
> - chan_array[i].type = IIO_VOLTAGE;
> + chan_array[i].type = rzg2l_adc_channels[channel].type;
> chan_array[i].indexed = 1;
> chan_array[i].channel = channel;
> - chan_array[i].info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
> - chan_array[i].datasheet_name = rzg2l_adc_channel_name[channel];
> + if (rzg2l_adc_channels[channel].type == IIO_VOLTAGE)
> + chan_array[i].info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
> + else
> + chan_array[i].info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED);

Make it raw, but I'm curious we have no _SCALE on this device. Do we really have no idea
of the calibration of these channels?

> + chan_array[i].datasheet_name = rzg2l_adc_channels[channel].name;
> i++;
> }
>
> @@ -386,7 +425,7 @@ static int rzg2l_adc_hw_init(struct device *dev, struct rzg2l_adc *adc)
> reg &= ~RZG2L_ADM3_ADCMP_MASK;
> reg &= ~hw_params->adsmp_mask;
> reg |= FIELD_PREP(RZG2L_ADM3_ADCMP_MASK, hw_params->default_adcmp) |
> - hw_params->default_adsmp;
> + hw_params->default_adsmp[0];
>
> rzg2l_adc_writel(adc, RZG2L_ADM(3), reg);
>
> @@ -479,7 +518,7 @@ static int rzg2l_adc_probe(struct platform_device *pdev)
> static const struct rzg2l_adc_hw_params rzg2l_hw_params = {
> .num_channels = 8,
> .default_adcmp = 0xe,
> - .default_adsmp = 0x578,
> + .default_adsmp = { 0x578 },
> .adsmp_mask = GENMASK(15, 0),
> .adint_inten_mask = GENMASK(7, 0),
> .adivc = true