Date:   Fri, 17 Feb 2023 14:29:59 +0200
From:   Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To:     Mike Looijmans <mike.looijmans@topic.nl>
Cc:     devicetree@vger.kernel.org, linux-iio@vger.kernel.org,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Caleb Connolly <caleb.connolly@linaro.org>,
        ChiYuan Huang <cy_huang@richtek.com>,
        ChiaEn Wu <chiaen_wu@richtek.com>,
        Cosmin Tanislav <demonsingur@gmail.com>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Ibrahim Tilki <Ibrahim.Tilki@analog.com>,
        Jonathan Cameron <jic23@kernel.org>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Marcelo Schmitt <marcelo.schmitt1@gmail.com>,
        Ramona Bolboaca <ramona.bolboaca@analog.com>,
        William Breathitt Gray <william.gray@linaro.org>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] iio: adc: Add driver for TI ADS1100 and ADS1000 chips
Message-ID: <Y+9zR3bhlEMuma66@smile.fi.intel.com>
References: <20230217093128.8344-1-mike.looijmans@topic.nl>
 <20230217093128.8344-2-mike.looijmans@topic.nl>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20230217093128.8344-2-mike.looijmans@topic.nl>
Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
Precedence: bulk

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