Re: [PATCH v3 2/2] iio: adc: Add driver for the TI ADS8344 A/DC chips

[Jonathan Cameron <jic23@kernel.org>]

On Fri, 12 Apr 2019 11:15:37 +0200
Gregory CLEMENT <gregory.clement@bootlin.com> wrote:

> This adds support for the Texas Instruments ADS8344 ADC chip. This chip
> has a 16-bit 8-Channel ADC and is access directly through SPI.
> 
> Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Applied to the togreg branch of iio.git and pushed out as testing
for the autobuilders to play with it.

Thanks,

Jonathan

> ---
>  drivers/iio/adc/Kconfig      |  10 ++
>  drivers/iio/adc/Makefile     |   1 +
>  drivers/iio/adc/ti-ads8344.c | 204 +++++++++++++++++++++++++++++++++++
>  3 files changed, 215 insertions(+)
>  create mode 100644 drivers/iio/adc/ti-ads8344.c
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 76db6e5cc296..447d3a871746 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -967,6 +967,16 @@ config TI_ADS7950
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called ti-ads7950.
>  
> +config TI_ADS8344
> +	tristate "Texas Instruments ADS8344"
> +	depends on SPI && OF
> +	help
> +	  If you say yes here you get support for Texas Instruments ADS8344
> +	  ADC chips
> +
> +	  This driver can also be built as a module. If so, the module will be
> +	  called ti-ads8344.
> +
>  config TI_ADS8688
>  	tristate "Texas Instruments ADS8688"
>  	depends on SPI && OF
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 6fcebd167524..1f3ae934111d 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -87,6 +87,7 @@ obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
>  obj-$(CONFIG_TI_ADC161S626) += ti-adc161s626.o
>  obj-$(CONFIG_TI_ADS1015) += ti-ads1015.o
>  obj-$(CONFIG_TI_ADS7950) += ti-ads7950.o
> +obj-$(CONFIG_TI_ADS8344) += ti-ads8344.o
>  obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
>  obj-$(CONFIG_TI_ADS124S08) += ti-ads124s08.o
>  obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
> diff --git a/drivers/iio/adc/ti-ads8344.c b/drivers/iio/adc/ti-ads8344.c
> new file mode 100644
> index 000000000000..e1649e237edc
> --- /dev/null
> +++ b/drivers/iio/adc/ti-ads8344.c
> @@ -0,0 +1,204 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * ADS8344 16-bit 8-Channel ADC driver
> + *
> + * Author: Gregory CLEMENT <gregory.clement@bootlin.com>
> + *
> + * Datasheet: http://www.ti.com/lit/ds/symlink/ads8344.pdf
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/iio.h>
> +#include <linux/module.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/spi/spi.h>
> +
> +#define ADS8344_START BIT(7)
> +#define ADS8344_SINGLE_END BIT(2)
> +#define ADS8344_CHANNEL(channel) ((channel) << 4)
> +#define ADS8344_CLOCK_INTERNAL 0x2 /* PD1 = 1 and PD0 = 0 */
> +
> +struct ads8344 {
> +	struct spi_device *spi;
> +	struct regulator *reg;
> +	/*
> +	 * Lock protecting access to adc->tx_buff and rx_buff,
> +	 * especially from concurrent read on sysfs file.
> +	 */
> +	struct mutex lock;
> +
> +	u8 tx_buf ____cacheline_aligned;
> +	u16 rx_buf;
> +};
> +
> +#define ADS8344_VOLTAGE_CHANNEL(chan, si)				\
> +	{								\
> +		.type = IIO_VOLTAGE,					\
> +		.indexed = 1,						\
> +		.channel = chan,					\
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> +	}
> +
> +#define ADS8344_VOLTAGE_CHANNEL_DIFF(chan1, chan2, si)			\
> +	{								\
> +		.type = IIO_VOLTAGE,					\
> +		.indexed = 1,						\
> +		.channel = (chan1),					\
> +		.channel2 = (chan2),					\
> +		.differential = 1,					\
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> +	}
> +
> +static const struct iio_chan_spec ads8344_channels[] = {
> +	ADS8344_VOLTAGE_CHANNEL(0, 0),
> +	ADS8344_VOLTAGE_CHANNEL(1, 4),
> +	ADS8344_VOLTAGE_CHANNEL(2, 1),
> +	ADS8344_VOLTAGE_CHANNEL(3, 5),
> +	ADS8344_VOLTAGE_CHANNEL(4, 2),
> +	ADS8344_VOLTAGE_CHANNEL(5, 6),
> +	ADS8344_VOLTAGE_CHANNEL(6, 3),
> +	ADS8344_VOLTAGE_CHANNEL(7, 7),
> +	ADS8344_VOLTAGE_CHANNEL_DIFF(0, 1, 8),
> +	ADS8344_VOLTAGE_CHANNEL_DIFF(2, 3, 9),
> +	ADS8344_VOLTAGE_CHANNEL_DIFF(4, 5, 10),
> +	ADS8344_VOLTAGE_CHANNEL_DIFF(6, 7, 11),
> +	ADS8344_VOLTAGE_CHANNEL_DIFF(1, 0, 12),
> +	ADS8344_VOLTAGE_CHANNEL_DIFF(3, 2, 13),
> +	ADS8344_VOLTAGE_CHANNEL_DIFF(5, 4, 14),
> +	ADS8344_VOLTAGE_CHANNEL_DIFF(7, 6, 15),
> +};
> +
> +static int ads8344_adc_conversion(struct ads8344 *adc, int channel,
> +				  bool differential)
> +{
> +	struct spi_device *spi = adc->spi;
> +	int ret;
> +
> +	adc->tx_buf = ADS8344_START;
> +	if (!differential)
> +		adc->tx_buf |= ADS8344_SINGLE_END;
> +	adc->tx_buf |= ADS8344_CHANNEL(channel);
> +	adc->tx_buf |= ADS8344_CLOCK_INTERNAL;
> +
> +	ret = spi_write(spi, &adc->tx_buf, 1);
> +	if (ret)
> +		return ret;
> +
> +	udelay(9);
> +
> +	ret = spi_read(spi, &adc->rx_buf, 2);
> +	if (ret)
> +		return ret;
> +
> +	return adc->rx_buf;
> +}
> +
> +static int ads8344_read_raw(struct iio_dev *iio,
> +			    struct iio_chan_spec const *channel, int *value,
> +			    int *shift, long mask)
> +{
> +	struct ads8344 *adc = iio_priv(iio);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		mutex_lock(&adc->lock);
> +		*value = ads8344_adc_conversion(adc, channel->scan_index,
> +						channel->differential);
> +		mutex_unlock(&adc->lock);
> +		if (*value < 0)
> +			return *value;
> +
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		*value = regulator_get_voltage(adc->reg);
> +		if (*value < 0)
> +			return *value;
> +
> +		/* convert regulator output voltage to mV */
> +		*value /= 1000;
> +		*shift = 16;
> +
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_info ads8344_info = {
> +	.read_raw = ads8344_read_raw,
> +};
> +
> +static int ads8344_probe(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev;
> +	struct ads8344 *adc;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	adc = iio_priv(indio_dev);
> +	adc->spi = spi;
> +	mutex_init(&adc->lock);
> +
> +	indio_dev->name = dev_name(&spi->dev);
> +	indio_dev->dev.parent = &spi->dev;
> +	indio_dev->dev.of_node = spi->dev.of_node;
> +	indio_dev->info = &ads8344_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = ads8344_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(ads8344_channels);
> +
> +	adc->reg = devm_regulator_get(&spi->dev, "vref");
> +	if (IS_ERR(adc->reg))
> +		return PTR_ERR(adc->reg);
> +
> +	ret = regulator_enable(adc->reg);
> +	if (ret)
> +		return ret;
> +
> +	spi_set_drvdata(spi, indio_dev);
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret) {
> +		regulator_disable(adc->reg);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int ads8344_remove(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> +	struct ads8344 *adc = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +	regulator_disable(adc->reg);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id ads8344_of_match[] = {
> +	{ .compatible = "ti,ads8344", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, ads8344_dt_ids);
> +
> +static struct spi_driver ads8344_driver = {
> +	.driver = {
> +		.name = "ads8344",
> +		.of_match_table = ads8344_of_match,
> +	},
> +	.probe = ads8344_probe,
> +	.remove = ads8344_remove,
> +};
> +module_spi_driver(ads8344_driver);
> +
> +MODULE_AUTHOR("Gregory CLEMENT <gregory.clement@bootlin.com>");
> +MODULE_DESCRIPTION("ADS8344 driver");
> +MODULE_LICENSE("GPL");