Re: [PATCH v3 2/2] iio: adc: Add TI ADS1100 and ADS1000

[Mike Looijmans]

Met vriendelijke groet / kind regards,

Mike Looijmans
System Expert


TOPIC Embedded Products B.V.
Materiaalweg 4, 5681 RJ Best
The Netherlands

T: +31 (0) 499 33 69 69
E: mike.looijmans@xxxxxxxxxxxxxxxxx
W: www.topic.nl

Please consider the environment before printing this e-mail
On 04-03-2023 18:57, Jonathan Cameron wrote:
> On Tue, 28 Feb 2023 07:31:51 +0100
> Mike Looijmans <mike.looijmans@xxxxxxxx> wrote:
>
> > The ADS1100 is a 16-bit ADC (at 8 samples per second).
> > The ADS1000 is similar, but has a fixed data rate.
> >
> > Signed-off-by: Mike Looijmans <mike.looijmans@xxxxxxxx>
> Hi Mike,
>
> A few minor things + one request for a test as trying to chase a possible
> ref count overflow around the runtime_pm was giving me a enough of a headache
> that it's easier to ask you just to poke it and see.  If it doesn't fail as
> I expect I'll take a closer look!

Will do, but it may take a few days to get access to the hardware again. 
I'll report on that later.

> > +static int ads1100_set_scale(struct ads1100_data *data, int val, int val2)
> > +{
> > +	int microvolts;
> > +	int gain;
> > +	int i;
> > +
> > +	/* With Vdd between 2.7 and 5V, the scale is always below 1 */
> > +	if (val)
> > +		return -EINVAL;
> > +
> > +	microvolts = regulator_get_voltage(data->reg_vdd);
> > +	/* Calculate: gain = ((microvolts / 1000) / (val2 / 1000000)) >> 15 */
> > +	gain = ((microvolts + BIT(14)) >> 15) * 1000 / val2;
> > +
> > +	for (i = 0; i < 4; i++) {
> > +		if (BIT(i) == gain) {
> > +			ads1100_set_config_bits(data, ADS1100_PGA_MASK, i);
> > +			return 0;
> > +		}
> > +	}
> Andy's suggestion of something like..
> 	if (!gain)
> 		return -EINVAL;
> 	i = ffs(gain);
> 	if (i >= 4 || BIT(i) != gain)
> 		return -EINVAL;
>
> 	ads...
>
> Is perhaps nicer than the loop.

Yes, takes out a loop.


> > +static void ads1100_disable_continuous(void *data)
> > +{
> > +	ads1100_set_config_bits(data, ADS1100_CFG_SC, ADS1100_SINGLESHOT);
> > +}
> > +
> > +static int ads1100_probe(struct i2c_client *client)
> > +{
> > +	struct iio_dev *indio_dev;
> > +	struct ads1100_data *data;
> > +	struct device *dev = &client->dev;
> > +	int ret;
> > +
> > +	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
> > +	if (!indio_dev)
> > +		return -ENOMEM;
> > +
> > +	data = iio_priv(indio_dev);
> > +	i2c_set_clientdata(client, indio_dev);
> You can avoid the slightly nasty mix of i2c_set_clientdata vs dev_get_drvdata()
> below by taking advantage of the fact you have a local dev pointer.
>
> 	dev_set_drvdata(dev, indio_dev);
> and no confusing mix is left.  Of course it's doing the same thing but to my
> mind slightly nicer to use the same one.

Since I don't need indio_dev anywhere, I might as well say this directly:

dev_set_drvdata(dev, data);

(Only the pm_ routines use this)

> ...

--
Mike Looijmans