linux-kernel - Re: [PATCH v6 2/2] iio: adc: add support for Nuvoton NCT7201

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Message-ID: <Z_95naiV7zpLokPr@smile.fi.intel.com>
Date: Wed, 16 Apr 2025 12:34:21 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Eason Yang <j2anfernee@...il.com>
Cc: jic23@...nel.org, lars@...afoo.de, robh@...nel.org, krzk+dt@...nel.org,
	conor+dt@...nel.org, dlechner@...libre.com, nuno.sa@...log.com,
	javier.carrasco.cruz@...il.com, gstols@...libre.com,
	alisadariana@...il.com, tgamblin@...libre.com,
	olivier.moysan@...s.st.com, antoniu.miclaus@...log.com,
	eblanc@...libre.com, joao.goncalves@...adex.com,
	tobias.sperling@...ting.com, marcelo.schmitt@...log.com,
	angelogioacchino.delregno@...labora.com,
	thomas.bonnefille@...tlin.com, herve.codina@...tlin.com,
	chanh@...amperecomputing.com, KWLIU@...oton.com,
	yhyang2@...oton.com, linux-iio@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 2/2] iio: adc: add support for Nuvoton NCT7201

On Wed, Apr 16, 2025 at 04:17:34PM +0800, Eason Yang wrote:
> Add Nuvoton NCT7201/NCT7202 system voltage monitor 12-bit ADC driver
> 
> NCT7201/NCT7202 supports up to 12 analog voltage monitor inputs and up
> to 4 SMBus addresses by ADDR pin. Meanwhile, ALERT# hardware event pins
> for independent alarm signals, and all the threshold values could be set
> for system protection without any timing delay. It also supports reset
> input RSTIN# to recover system from a fault condition.
> 
> Currently, only single-edge mode conversion and threshold events are
> supported.

...

> +#define NCT7201_REG_VIN(i)				(i)

This doesn't do anything useful. Why do you need this rather useless macro?

...

> +struct nct7201_chip_info {
> +	struct device *dev;

This can be derived from the respective regmap. No need to have it here.

> +	struct regmap *regmap;
> +	struct regmap *regmap16;
> +	int num_vin_channels;
> +	u16 vin_mask;
> +};

...

> +struct nct7201_adc_model_data {
> +	const char *model_name;
> +	const struct iio_chan_spec *channels;

> +	const int num_channels;

What is the meaning of const here?

> +	int num_vin_channels;
> +};

...

> +#define NCT7201_VOLTAGE_CHANNEL(num)					\
> +	{								\
> +		.type = IIO_VOLTAGE,					\
> +		.indexed = 1,						\
> +		.channel = (num + 1),					\

Parentheses are in a wrong place

> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> +		.address = num,						\
> +		.event_spec = nct7201_events,				\
> +		.num_event_specs = ARRAY_SIZE(nct7201_events),		\
> +	}

...

> +static int nct7201_write_event_config(struct iio_dev *indio_dev,
> +				      const struct iio_chan_spec *chan,
> +				      enum iio_event_type type,
> +				      enum iio_event_direction dir,
> +				      bool state)
> +{
> +	struct nct7201_chip_info *chip = iio_priv(indio_dev);
> +	unsigned int mask;
> +	int err;
> +
> +	if (chan->type != IIO_VOLTAGE)
> +		return -EOPNOTSUPP;

> +	mask = BIT(chan->address);

Just join this with the definition above.


> +	if (state)
> +		chip->vin_mask |= mask;
> +	else
> +		chip->vin_mask &= ~mask;
> +
> +	if (chip->num_vin_channels <= 8)
> +		err = regmap_write(chip->regmap, NCT7201_REG_CHANNEL_ENABLE_1,

Remove _1.

> +				   chip->vin_mask);
> +	else
> +		err = regmap_bulk_write(chip->regmap, NCT7201_REG_CHANNEL_ENABLE_1,
> +					&chip->vin_mask, sizeof(chip->vin_mask));

> +	if (err)
> +		return err;
> +
> +	return 0;

As simple as

	return err;

> +}

...

> +static int nct7201_init_chip(struct nct7201_chip_info *chip)
> +{
> +	struct device *dev = chip->dev;

Derive this from chip->regmap.

> +	__le16 data = cpu_to_le16(NCT7201_REG_CHANNEL_ENABLE_MASK);
> +	unsigned int value;
> +	int err;
> +
> +	err = regmap_write(chip->regmap, NCT7201_REG_CONFIGURATION,
> +			   NCT7201_BIT_CONFIGURATION_RESET);
> +	if (err)
> +		return dev_err_probe(dev, err, "Failed to reset chip\n");
> +
> +	/*
> +	 * After about 25 msecs, the device should be ready and then the Power
> +	 * Up bit will be set to 1. If not, wait for it.

"Up bit" is odd, please be more specific.

> +	 */
> +	fsleep(25000);

+ Blank line.

> +	err = regmap_read(chip->regmap, NCT7201_REG_BUSY_STATUS, &value);
> +	if (err)
> +		return dev_err_probe(dev, err, "Failed to read busy status\n");
> +	if (!(value & NCT7201_BIT_PWR_UP))
> +		return dev_err_probe(dev, -EIO, "Failed to power up after reset\n");
> +
> +	/* Enable Channel */
> +	if (chip->num_vin_channels <= 8)
> +		err = regmap_write(chip->regmap, NCT7201_REG_CHANNEL_ENABLE_1,
> +				   NCT7201_REG_CHANNEL_ENABLE_MASK);
> +	else
> +		err = regmap_bulk_write(chip->regmap, NCT7201_REG_CHANNEL_ENABLE_1,
> +					&data, sizeof(data));
> +	if (err)
> +		return dev_err_probe(dev, err, "Failed to enable channel\n");
> +
> +	err = regmap_bulk_read(chip->regmap, NCT7201_REG_CHANNEL_ENABLE_1,
> +			       &chip->vin_mask, sizeof(chip->vin_mask));
> +	if (err)
> +		return dev_err_probe(dev, err,
> +				     "Failed to read channel enable register\n");
> +
> +	/* Start monitoring if needed */
> +	err = regmap_set_bits(chip->regmap, NCT7201_REG_CONFIGURATION,
> +			      NCT7201_BIT_CONFIGURATION_START);
> +	if (err)
> +		return dev_err_probe(dev, err, "Failed to start monitoring\n");
> +
> +	return 0;
> +}

...

> +	ret = nct7201_init_chip(chip);
> +	if (ret < 0)

Why ' < 0' ?

> +		return ret;

-- 
With Best Regards,
Andy Shevchenko