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

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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
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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





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