Re: [PATCH 1/3] iio: adc: add ltc2309 support

[Krzysztof Kozlowski]

On 24/08/2023 18:55, Liam Beguin wrote:
> The LTC2309 is an 8-Channel, 12-Bit SAR ADC with an I2C Interface.
> 
> This implements support for all single-ended and differential channels,
> in unipolar mode only.
> 
> Signed-off-by: Liam Beguin <liambeguin@xxxxxxxxx>
> ---
>  drivers/iio/adc/Kconfig   |  10 ++
>  drivers/iio/adc/Makefile  |   1 +
>  drivers/iio/adc/ltc2309.c | 232 ++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 243 insertions(+)
> 



> +static int ltc2309_read_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan, int *val,
> +			    int *val2, long mask)
> +{
> +	struct ltc2309 *ltc2309 = iio_priv(indio_dev);
> +	u16 buf;
> +	int ret;
> +	u8 din;
> +
> +	mutex_lock(&ltc2309->lock);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		din = FIELD_PREP(LTC2309_DIN_CH_MASK, chan->address & 0x0f) |
> +			FIELD_PREP(LTC2309_DIN_UNI, 1) |
> +			FIELD_PREP(LTC2309_DIN_SLEEP, 0);
> +
> +		ret = i2c_smbus_write_byte(ltc2309->client, din);
> +		if (ret < 0) {
> +			dev_err(ltc2309->dev, "i2c command failed: %pe\n",
> +				ERR_PTR(ret));
> +			goto out;
> +		}
> +
> +		ret = i2c_master_recv(ltc2309->client, (char *)&buf, 2);
> +		if (ret < 0) {
> +			dev_err(ltc2309->dev, "i2c read failed: %pe\n",
> +				ERR_PTR(ret));
> +			goto out;
> +		}
> +
> +		*val = be16_to_cpu(buf) >> 4;
> +
> +		ret = IIO_VAL_INT;
> +		break;
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = ltc2309->vref_mv;
> +		*val2 = LTC2309_ADC_RESOLUTION;
> +		ret = IIO_VAL_FRACTIONAL_LOG2;

Why this case is in critical section?

> +		break;
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +
> +out:
> +	mutex_unlock(&ltc2309->lock);
> +	return ret;
> +}
> +
> +static const struct iio_info ltc2309_info = {
> +	.read_raw = ltc2309_read_raw,
> +};
> +
> +static int ltc2309_probe(struct i2c_client *client,
> +			 const struct i2c_device_id *id)
> +{
> +	struct iio_dev *indio_dev;
> +	struct ltc2309 *ltc2309;
> +	int ret = 0;
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*ltc2309));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	i2c_set_clientdata(client, indio_dev);
> +
> +	ltc2309 = iio_priv(indio_dev);
> +	ltc2309->dev = &indio_dev->dev;
> +	ltc2309->client = client;
> +	ltc2309->vref_mv = 4096; /* Default to the internal ref */
> +
> +	indio_dev->name = DRIVER_NAME;
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = ltc2309_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(ltc2309_channels);
> +	indio_dev->info = &ltc2309_info;
> +
> +	ltc2309->refcomp = devm_regulator_get_optional(&client->dev, "refcomp");
> +	if (!IS_ERR_OR_NULL(ltc2309->refcomp)) {
> +		ret = regulator_enable(ltc2309->refcomp);
> +		if (ret) {
> +			dev_err(ltc2309->dev, "failed to enable REFCOMP\n");
> +			return ret;
> +		}
> +
> +		ret = regulator_get_voltage(ltc2309->refcomp);
> +		if (ret < 0)

You have unbalanced regulator. Same in all further error paths.

> +			return ret;
> +
> +		ltc2309->vref_mv = ret / 1000;
> +		if (ret)
> +			return ret;
> +	}
> +
> +	mutex_init(&ltc2309->lock);
> +
> +	return devm_iio_device_register(&client->dev, indio_dev);
> +}
> +


Best regards,
Krzysztof