On 11/19/2012 09:21 AM, Thierry Reding wrote:
> Add support for reading conversion results from the ADC and provide them
> through a single IIO channel. A proper scaling factor is also exported
> based on the reference voltage provided by a regulator.
>
> Signed-off-by: Thierry Reding <thierry.reding@xxxxxxxxxxxxxxxxx>
> ---
[...]
> +static int adc081c_read_raw(struct iio_dev *iio,
> + struct iio_chan_spec const *channel, int *value,
> + int *micro, long mask)
> +{
> + struct adc081c *adc = iio_priv(iio);
> + int err, scale;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + err = i2c_smbus_read_word_swapped(adc->i2c, REG_CONV_RES);
> + if (err < 0)
> + return err;
> +
> + *value = (err >> 4) & 0xff;
> + return IIO_VAL_INT;
> +
> + case IIO_CHAN_INFO_SCALE:
> + err = regulator_get_voltage(adc->ref);
> + if (err < 0)
> + return err;
> +
> + scale = err / 255;
Shouldn't this be 256?
> +
> + *value = scale / 1000000;
> + *micro = scale % 1000000;
scale for voltages is in microvolt, so I think it this is off by a factor of
1000.
For ADCs it often makes sense to use IIO_VAL_FRACTIONAL_LOG2 with the val
being set to the reference voltage (in mV) and val2 being set to the number
of bits.
E.g in your case
*val = err / 1000;
*val2 = 8;
> +
> + return IIO_VAL_INT_PLUS_MICRO;
> +
> + default:
> + break;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static const struct iio_info adc081c_info = {
> + .read_raw = adc081c_read_raw,
> + .driver_module = THIS_MODULE,
> +};
> +
> +static int adc081c_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct iio_dev *iio;
> + struct adc081c *adc;
> + int err;
> +
> + if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
> + return -ENODEV;
> +
> + iio = iio_device_alloc(sizeof(*adc));
> + if (!iio)
> + return -ENOMEM;
> +
> + adc = iio_priv(iio);
> + adc->i2c = client;
> +
> + adc->ref = regulator_get(&client->dev, "vref");
> + if (IS_ERR(adc->ref)) {
> + err = PTR_ERR(adc->ref);
> + goto iio_free;
> + }
> +
> + err = regulator_enable(adc->ref);
> + if (err < 0)
> + goto regulator_put;
> +
> + iio->dev.parent = &client->dev;
> + iio->name = dev_name(&client->dev);
> + iio->modes = INDIO_DIRECT_MODE;
> + iio->info = &adc081c_info;
> +
> + adc->channel.type = IIO_VOLTAGE;
> + adc->channel.info_mask = IIO_CHAN_INFO_SCALE_SHARED_BIT |
> + IIO_CHAN_INFO_RAW_SEPARATE_BIT;
nitpick: Since it is the same for each driver I'd make the channel static const.
> +
> + iio->channels = &adc->channel;
> + iio->num_channels = 1;
> +
[...]
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