Re: [PATCH v11 8/8] iio: adc: ad4851: add ad485x driver

[David Lechner]

On 1/27/25 4:57 AM, Antoniu Miclaus wrote:
> Add support for the AD485X a fully buffered, 8-channel simultaneous
> sampling, 16/20-bit, 1 MSPS data acquisition system (DAS) with
> differential, wide common-mode range inputs.
> 
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@xxxxxxxxxx>
> ---

I think we have the important bits sorted now (i.e. userspace-facing stuff).
Just noticed a few minor things in the latest revision.


> +static int ad4851_setup(struct ad4851_state *st)
> +{
> +	unsigned int product_id;
> +	int ret;
> +
> +	if (st->pd_gpio) {
> +		/* To initiate a global reset, bring the PD pin high twice */
> +		gpiod_set_value(st->pd_gpio, 1);
> +		fsleep(1);
> +		gpiod_set_value(st->pd_gpio, 0);
> +		fsleep(1);
> +		gpiod_set_value(st->pd_gpio, 1);
> +		fsleep(1);
> +		gpiod_set_value(st->pd_gpio, 0);
> +		fsleep(1000);
> +	} else {
> +		ret = regmap_set_bits(st->regmap, AD4851_REG_INTERFACE_CONFIG_A,
> +				      AD4851_SW_RESET);
> +		if (ret)
> +			return ret;

Do we also need fsleep() after software reset?

> +	}
> +

...

> +static int ad4851_parse_channels(struct iio_dev *indio_dev,
> +				 const struct iio_chan_spec ad4851_chan)
> +{
> +	struct ad4851_state *st = iio_priv(indio_dev);
> +	struct device *dev = &st->spi->dev;
> +	struct iio_chan_spec *channels;
> +	unsigned int num_channels, reg;
> +	unsigned int index = 0;
> +	int ret;
> +
> +	num_channels = device_get_child_node_count(dev);
> +	if (num_channels > AD4851_MAX_CH_NR)
> +		return dev_err_probe(dev, -EINVAL, "Too many channels: %u\n",
> +				     num_channels);
> +
> +	channels = devm_kcalloc(dev, num_channels, sizeof(*channels), GFP_KERNEL);
> +	if (!channels)
> +		return -ENOMEM;
> +
> +	indio_dev->channels = channels;
> +	indio_dev->num_channels = num_channels;
> +
> +	device_for_each_child_node_scoped(dev, child) {
> +		ret = fwnode_property_read_u32(child, "reg", &reg);
> +		if (reg >= AD4851_MAX_CH_NR)
> +			return dev_err_probe(dev, ret,
> +					     "Invalid channel number\n");

Need to check ret first, otherwise reg may be unintialized.

> +		if (ret)
> +			return dev_err_probe(dev, ret,
> +					     "Missing channel number\n");
> +		*channels = ad4851_chan;
> +		channels->scan_index = index++;
> +		channels->channel = reg;
> +
> +		if (fwnode_property_present(child, "diff-channels")) {
> +			channels->channel2 = reg + st->info->max_channels;
> +			channels->differential = 1;
> +		}
> +
> +		channels++;
> +
> +		st->bipolar_ch[reg] = fwnode_property_read_bool(child, "bipolar");
> +
> +		if (st->bipolar_ch[reg]) {
> +			channels->scan_type.sign = 's';
> +		} else {
> +			ret = regmap_write(st->regmap, AD4851_REG_CHX_SOFTSPAN(reg),
> +					   AD4851_SOFTSPAN_0V_40V);
> +			if (ret)
> +				return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int ad4857_parse_channels(struct iio_dev *indio_dev)
> +{
> +	const struct iio_chan_spec ad4851_chan = AD4857_IIO_CHANNEL;
> +
> +	return ad4851_parse_channels(indio_dev, ad4851_chan);
> +}
> +
> +static int ad4858_parse_channels(struct iio_dev *indio_dev)
> +{
> +	struct ad4851_state *st = iio_priv(indio_dev);
> +	struct device *dev = &st->spi->dev;
> +	struct iio_chan_spec *ad4851_channels;
> +	const struct iio_chan_spec ad4851_chan = AD4858_IIO_CHANNEL;
> +	int ret;
> +
> +	ad4851_channels = (struct iio_chan_spec *)indio_dev->channels;
> +
> +	ret = ad4851_parse_channels(indio_dev, ad4851_chan);
> +	if (ret)
> +		return ret;
> +
> +	device_for_each_child_node_scoped(dev, child) {
> +		ad4851_channels->has_ext_scan_type = 1;
> +		if (fwnode_property_present(child, "bipolar")) {

fwnode_property_read_bool() 

(to be consistent with same check in ad4851_parse_channels())

> +			ad4851_channels->ext_scan_type = ad4851_scan_type_20_b;
> +			ad4851_channels->num_ext_scan_type = ARRAY_SIZE(ad4851_scan_type_20_b);
> +
> +		} else {
> +			ad4851_channels->ext_scan_type = ad4851_scan_type_20_u;
> +			ad4851_channels->num_ext_scan_type = ARRAY_SIZE(ad4851_scan_type_20_u);
> +		}
> +		ad4851_channels++;
> +	}
> +
> +	return 0;
> +}
> +