Re: [PATCH v2 04/25] iio: adc: add support for X-Powers AXP20X and AXP22X PMICs ADCs

Quentin Schulz
2017-01-28T15:22:32Z

Hi Jonathan

On 28/01/2017 15:49, Jonathan Cameron wrote:
> On 27/01/17 08:54, Quentin Schulz wrote:
>> The X-Powers AXP20X and AXP22X PMICs have multiple ADCs. They expose the
>> battery voltage, battery charge and discharge currents, AC-in and VBUS
>> voltages and currents, 2 GPIOs muxable in ADC mode and PMIC temperature.
>>
>> This adds support for most of AXP20X and AXP22X ADCs.
>>
>> Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
> Pretty good, but not everything seems to be cleaned up on error paths
> in probe.
>
> A few other suggestions / questions inline.
>
> Jonathan
>> ---
[...]
>> +static int axp20x_adc_raw(struct iio_dev *indio_dev,
>> + struct iio_chan_spec const *chan, int *val)
>> +{
>> + struct axp20x_adc_iio *info = iio_priv(indio_dev);
>> + int size = 12;
>> +
>> + switch (chan->type) {
>> + case IIO_CURRENT:
>> + /*
>> + * Unlike the Chinese datasheets tell, the charging current is
>> + * stored on 12 bits, not 13 bits.
>> + */
>> + if (chan->channel == AXP20X_BATT_DISCHRG_I)
>> + size = 13;
> Given I don't think you can get here without it being current, voltage or temp;
> couldn't this be done more cleanly with
> if ((chan->type == IIO_CURRENT) && (chan->channel == AXP20X_BAT_DISCHRG_I))
> size = 13;
>
> and have the rest in the normal code flow?
>

Indeed.

>> + case IIO_VOLTAGE:
>> + case IIO_TEMP:
>> + *val = axp20x_read_variable_width(info->regmap, chan->address,
>> + size);
>> + if (*val < 0)
>> + return *val;
>> +
>> + return IIO_VAL_INT;
>> +
>> + default:
>> + return -EINVAL;
>> + }
>> +}
[...]
>> +static int axp22x_adc_scale(struct iio_chan_spec const *chan, int *val,
>> + int *val2)
>> +{
>> + switch (chan->type) {
>> + case IIO_VOLTAGE:
>> + if (chan->channel != AXP22X_BATT_V)
>> + return -EINVAL;
>> +
>> + *val = 1;
>> + *val2 = 100000;
>> + return IIO_VAL_INT_PLUS_MICRO;
> A fixed scale of 1.1x? (just checking)

Yes, there is only one voltage exposed for AXP22X PMICs: the battery
voltage which has a scale of 1.1 (for mV).

[...]
>> +static int axp20x_probe(struct platform_device *pdev)
>> +{
>> + struct axp20x_adc_iio *info;
>> + struct iio_dev *indio_dev;
>> + struct axp20x_dev *axp20x_dev;
>> + int ret;
>> +
>> + axp20x_dev = dev_get_drvdata(pdev->dev.parent);
>> +
>> + indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*info));
>> + if (!indio_dev)
>> + return -ENOMEM;
>> +
>> + info = iio_priv(indio_dev);
>> + platform_set_drvdata(pdev, indio_dev);
>> +
>> + info->regmap = axp20x_dev->regmap;
>> + indio_dev->name = dev_name(&pdev->dev);
> Not sure on this name - what does end up as? Expected to be
> a description of the part so in this case something like axp209-adc.
> I've been lax at picking up on this in the past and it's led to some
> crazy naming that is no use at all to userspace. Basically this
> name just provides a convenient user readable name for userspace apps to
> use.
>

ACK. Should we have a different name for AXP20X and AXP22X PMICs?

>> + indio_dev->dev.parent = &pdev->dev;
>> + indio_dev->dev.of_node = pdev->dev.of_node;
>> + indio_dev->modes = INDIO_DIRECT_MODE;
>> +
>> + info->data = (struct axp_data *)of_device_get_match_data(&pdev->dev);
>> +
>> + indio_dev->info = info->data->iio_info;
>> + indio_dev->num_channels = info->data->num_channels;
>> + indio_dev->channels = info->data->channels;
>> +
>> + /* Enable the ADCs on IP */
>> + regmap_write(info->regmap, AXP20X_ADC_EN1, info->data->adc_en1_mask);
>> +
>> + if (info->data->adc_en2)
>> + /* Enable GPIO0/1 and internal temperature ADCs */
>> + regmap_update_bits(info->regmap, AXP20X_ADC_EN2,
>> + AXP20X_ADC_EN2_MASK, AXP20X_ADC_EN2_MASK);
>> +
>> + /* Configure ADCs rate */
>> + regmap_update_bits(info->regmap, AXP20X_ADC_RATE, AXP20X_ADC_RATE_MASK,
>> + info->data->adc_rate(100));
>> +
>> + ret = iio_map_array_register(indio_dev, info->data->maps);
>> + if (ret < 0) {
>> + dev_err(&pdev->dev, "failed to register IIO maps: %d\n", ret);
> This should be disabling channels.

You mean disabling ADCs as it is done in the remove? If so, indeed.

>> + return ret;
>> + }
>> +
>> + ret = iio_device_register(indio_dev);
>> + if (ret < 0) {
>> + dev_err(&pdev->dev, "could not register the device\n");
>> + regmap_write(info->regmap, AXP20X_ADC_EN1, 0);
>> +
>> + if (info->data->adc_en2)
>> + regmap_write(info->regmap, AXP20X_ADC_EN2, 0);
> I'd expect to see a complete unwind of what has been done earlier in probe
> including iio_map_array_unregister.
>
> The traditional goto error* approach is probably worth having here to
> make sure the unwind makes sense.

Indeed.

>> +
>> + return ret;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int axp20x_remove(struct platform_device *pdev)
>> +{
>> + struct axp20x_adc_iio *info;
>> + struct iio_dev *indio_dev = platform_get_drvdata(pdev);
>> +
>> + info = iio_priv(indio_dev);
>> +
>> + iio_device_unregister(indio_dev);
> iio_map_array_unregister?

Yes. I see iio_device_unregister already disable all buffers, why not
unregistering the map array as well in this function?

[...]
Thanks,
Quentin

--
Quentin Schulz, Free Electrons
Embedded Linux and Kernel engineering