linux-kernel - Re: [PATCH v5 2/3] iio: adc: Support ROHM BD79112 ADC/GPIO

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Message-ID: <aMge0jYwYCiY72Yb@smile.fi.intel.com>
Date: Mon, 15 Sep 2025 17:12:34 +0300
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Matti Vaittinen <mazziesaccount@...il.com>
Cc: Jonathan Cameron <jic23@...nel.org>,
	David Lechner <dlechner@...libre.com>,
	Nuno Sá <nuno.sa@...log.com>,
	Andy Shevchenko <andy@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>, linux-iio@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-gpio@...r.kernel.org
Subject: Re: [PATCH v5 2/3] iio: adc: Support ROHM BD79112 ADC/GPIO

On Mon, Sep 15, 2025 at 10:12:43AM +0300, Matti Vaittinen wrote:
> The ROHM BD79112 is an ADC/GPIO with 32 channels. The channel inputs can
> be used as ADC or GPIO. Using the GPIOs as IRQ sources isn't supported.
> 
> The ADC is 12-bit, supporting input voltages up to 5.7V, and separate I/O
> voltage supply. Maximum SPI clock rate is 20 MHz (10 MHz with
> daisy-chain configuration) and maximum sampling rate is 1MSPS.
> 
> The IC does also support CRC but it is not implemented in the driver.

...

> +static int bd79112_probe(struct spi_device *spi)
> +{
> +	struct bd79112_data *data;
> +	struct iio_dev *iio_dev;
> +	struct iio_chan_spec *cs;
> +	struct device *dev = &spi->dev;
> +	unsigned long gpio_pins, pin;
> +	unsigned int i;
> +	int ret;
> +
> +	iio_dev = devm_iio_device_alloc(dev, sizeof(*data));
> +	if (!iio_dev)
> +		return -ENOMEM;
> +
> +	data = iio_priv(iio_dev);
> +	data->spi = spi;
> +	data->dev = dev;
> +	data->map = devm_regmap_init(dev, NULL, data, &bd79112_regmap);
> +	if (IS_ERR(data->map))
> +		return dev_err_probe(dev, PTR_ERR(data->map),
> +				     "Failed to initialize Regmap\n");
> +
> +	ret = devm_regulator_get_enable_read_voltage(dev, "vdd");
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "Failed to get the Vdd\n");

> +	data->vref_mv = ret / 1000;

I still think moving to _mV is the right thing to do.
There is no 'mv' in the physics for Volts.

> +	ret = devm_regulator_get_enable(dev, "iovdd");
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "Failed to enable I/O voltage\n");
> +
> +	data->read_xfer[0].tx_buf = &data->read_tx[0];
> +	data->read_xfer[0].len = sizeof(data->read_tx);
> +	data->read_xfer[0].cs_change = 1;
> +	data->read_xfer[1].rx_buf = &data->read_rx;
> +	data->read_xfer[1].len = sizeof(data->read_rx);
> +	spi_message_init_with_transfers(&data->read_msg, data->read_xfer, 2);

> +	devm_spi_optimize_message(dev, spi, &data->read_msg);

And if it fails?..

> +	data->write_xfer.tx_buf = &data->reg_write_tx[0];
> +	data->write_xfer.len = sizeof(data->reg_write_tx);
> +	spi_message_init_with_transfers(&data->write_msg, &data->write_xfer, 1);
> +	devm_spi_optimize_message(dev, spi, &data->write_msg);
> +
> +	ret = devm_iio_adc_device_alloc_chaninfo_se(dev, &bd79112_chan_template,
> +						    BD79112_MAX_NUM_CHANNELS - 1,
> +						    &cs);
> +
> +	/* Register all pins as GPIOs if there are no ADC channels */
> +	if (ret == -ENOENT)
> +		goto register_gpios;
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	iio_dev->num_channels = ret;
> +	iio_dev->channels = cs;
> +
> +	for (i = 0; i < iio_dev->num_channels; i++)
> +		cs[i].datasheet_name = bd79112_chan_names[cs[i].channel];
> +
> +	iio_dev->info = &bd79112_info;
> +	iio_dev->name = "bd79112";
> +	iio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	/*
> +	 * Ensure all channels are ADCs. This allows us to register the IIO
> +	 * device early (before checking which pins are to be used for GPIO)
> +	 * without having to worry about some pins being initially used for
> +	 * GPIO.
> +	 */
> +	for (i = 0; i < BD79112_NUM_GPIO_EN_REGS; i++) {
> +		ret = regmap_write(data->map, BD79112_FIRST_GPIO_EN_REG + i, 0);
> +		if (ret)
> +			return dev_err_probe(dev, ret,
> +					     "Failed to initialize channels\n");
> +	}
> +
> +	ret = devm_iio_device_register(data->dev, iio_dev);
> +	if (ret)
> +		return dev_err_probe(data->dev, ret, "Failed to register ADC\n");
> +
> +register_gpios:
> +	gpio_pins = bd79112_get_gpio_pins(iio_dev->channels,
> +					  iio_dev->num_channels);
> +
> +	/* If all channels are reserved for ADC, then we're done. */
> +	if (!gpio_pins)
> +		return 0;
> +
> +	/* Default all the GPIO pins to GPI */
> +	for_each_set_bit(pin, &gpio_pins, BD79112_MAX_NUM_CHANNELS) {
> +		ret = bd79112_gpio_dir_set(data, pin, GPIO_LINE_DIRECTION_IN);
> +		if (ret)
> +			return dev_err_probe(dev, ret,
> +					     "Failed to mark pin as GPI\n");
> +	}
> +
> +	data->gpio_valid_mask = gpio_pins;
> +	data->gc = bd79112_gpio_chip;
> +	data->gc.parent = dev;
> +
> +	return devm_gpiochip_add_data(dev, &data->gc, data);
> +}

-- 
With Best Regards,
Andy Shevchenko