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    SubjectRe: [PATCH 2/2] iio: adc: Add driver for TI ADS1100 and ADS1000 chips
    On Fri, Feb 17, 2023 at 10:31:28AM +0100, Mike Looijmans wrote:
    > The ADS1100 is a 16-bit ADC (at 8 samples per second).
    > The ADS1000 is similar, but has a fixed data rate.

    Any Datasheet link available?

    > Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>

    ...

    > +#define ADS1100_DR_MASK (BIT(3) | BIT(2))

    GENMASK()

    ...

    > +#define ADS1100_PGA_MASK (BIT(1) | BIT(0))

    Ditto.

    ...

    > +static const int ads1100_data_rate[] = {128, 32, 16, 8};
    > +static const int ads1100_data_rate_scale[] = {2048, 8192, 16384, 32768};
    > +static const int ads1100_gain[] = {1, 2, 4, 8};

    Do you need all of them as tables? They all can be derived from a single table
    or without any table at all (just three values).

    ...

    > +static const struct iio_chan_spec ads1100_channel = {
    > + .type = IIO_VOLTAGE,

    > + .differential = 0,
    > + .indexed = 0,

    No need.

    > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
    > + .info_mask_shared_by_all =
    > + BIT(IIO_CHAN_INFO_SCALE) |
    > + BIT(IIO_CHAN_INFO_HARDWAREGAIN) |
    > + BIT(IIO_CHAN_INFO_SAMP_FREQ),
    > + .info_mask_shared_by_all_available =
    > + BIT(IIO_CHAN_INFO_HARDWAREGAIN) |
    > + BIT(IIO_CHAN_INFO_SAMP_FREQ),
    > + .scan_type = {
    > + .sign = 's',
    > + .realbits = 16,
    > + .storagebits = 16,

    > + .shift = 0,

    No need.

    > + .endianness = IIO_CPU,
    > + },
    > + .datasheet_name = "AIN",
    > +};

    ...

    > + u8 config = (data->config & ~mask) | value;

    Traditional pattern is

    u8 config = (data->config & ~mask) | (value & mask);


    > +#ifdef CONFIG_PM

    Why?

    > +static int ads1100_set_power_state(struct ads1100_data *data, bool on)
    > +{
    > + int ret;
    > + struct device *dev = &data->client->dev;
    > +
    > + if (on) {
    > + ret = pm_runtime_resume_and_get(dev);
    > + } else {
    > + pm_runtime_mark_last_busy(dev);

    > + ret = pm_runtime_put_autosuspend(dev);

    Yes, in !CONFIG_PM this will return an error, but why do you care?

    > + }
    > +
    > + return ret < 0 ? ret : 0;
    > +}
    > +
    > +#else /* !CONFIG_PM */
    > +
    > +static int ads1100_set_power_state(struct ads1100_data *data, bool on)
    > +{
    > + return 0;
    > +}
    > +
    > +#endif /* !CONFIG_PM */

    ...

    > +static int ads1100_get_adc_result(struct ads1100_data *data, int chan, int *val)
    > +{
    > + int ret;

    > + u8 buffer[2];

    __be16 buffer;

    > +
    > + if (chan != 0)
    > + return -EINVAL;
    > +
    > + ret = i2c_master_recv(data->client, buffer, sizeof(buffer));
    > + if (ret < 0) {
    > + dev_err(&data->client->dev, "I2C read fail: %d\n", ret);
    > + return ret;
    > + }
    > +
    > + *val = (s16)(((u16)buffer[0] << 8) | buffer[1]);

    (s16)be16_to_cpu();

    But (s16) looks suspicious. Should you use sign_extend32()?

    > + return 0;
    > +}

    ...

    > +static int ads1100_set_gain(struct ads1100_data *data, int gain)
    > +{

    > + int i;

    unsigned

    > + for (i = 0; i < ARRAY_SIZE(ads1100_gain); ++i) {

    Pre-increment in the loops is non-standard in the kernel.
    Why do you need that?

    > + if (ads1100_gain[i] == gain) {
    > + return ads1100_set_config_bits(
    > + data, ADS1100_PGA_MASK, i);

    Strange indentation.

    > + }
    > + }
    > +
    > + return -EINVAL;
    > +}

    ...

    > +static int ads1100_set_data_rate(struct ads1100_data *data, int chan, int rate)

    Same comments as per above.

    ...

    > + dev_info(&data->client->dev, "%s %ld\n", __func__, mask);

    Useless noise in the logs.

    ...

    > + ret = iio_device_register(indio_dev);
    > + if (ret < 0) {
    > + dev_err(&client->dev, "Failed to register IIO device\n");
    > + return ret;

    return dev_err_probe();

    > + }

    ...

    > +#ifdef CONFIG_PM

    Drop it and use proper macros below.

    > +#endif

    ...

    > +static const struct dev_pm_ops ads1100_pm_ops = {
    > + SET_RUNTIME_PM_OPS(ads1100_runtime_suspend,
    > + ads1100_runtime_resume, NULL)
    > +};

    ...here and...

    ...

    > + .pm = &ads1100_pm_ops,

    ...here.

    ...

    > +

    Redundant blank line.

    > +module_i2c_driver(ads1100_driver);

    --
    With Best Regards,
    Andy Shevchenko


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