Re: [PATCH v2] iio: adc: add support for ADC0831/ADC0832/ADC0834/ADC0838 chips

[Jonathan Cameron <jic23@kernel.org>]

On 07/02/16 09:14, Akinobu Mita wrote:
> This adds ADC0831/ADC0832/ADC0834/ADC0838 8-bit ADC driver.
> I have tested with ADC0831 and ADC0832.  The remaining ADC0834 and
> ADC0838 are very similar to ADC0832.
> 
> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> Cc: Jonathan Cameron <jic23@kernel.org>
> Cc: Hartmut Knaack <knaack.h@gmx.de>
> Cc: Lars-Peter Clausen <lars@metafoo.de>
> Cc: Peter Meerwald <pmeerw@pmeerw.net>
Very nice.

Applied to the togreg branch of iio.git - initially pushed out
as testing to let the autobuilders play tennis with it.

Jonathan
> ---
> * v2 (Most changes are suggested by Jonathan Cameron)
> - rename driver name from ti-adc083x to ti-adc0832
> - simplify read_raw() by moving lock
> - fix remove() of driver with correct unwinding
> - enable untested chips (adc0831, adc0834, adc0838)
> - fix adc0831_adc_conversion as a result of testing
> 
>  .../devicetree/bindings/iio/adc/ti-adc0832.txt     |  19 ++
>  drivers/iio/adc/Kconfig                            |  10 +
>  drivers/iio/adc/Makefile                           |   1 +
>  drivers/iio/adc/ti-adc0832.c                       | 288 +++++++++++++++++++++
>  4 files changed, 318 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/ti-adc0832.txt
>  create mode 100644 drivers/iio/adc/ti-adc0832.c
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/ti-adc0832.txt b/Documentation/devicetree/bindings/iio/adc/ti-adc0832.txt
> new file mode 100644
> index 0000000..d911305
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/ti-adc0832.txt
> @@ -0,0 +1,19 @@
> +* Texas Instruments' ADC0831/ADC0832/ADC0832/ADC0838
> +
> +Required properties:
> + - compatible: Should be one of
> +	* "ti,adc0831"
> +	* "ti,adc0832"
> +	* "ti,adc0834"
> +	* "ti,adc0838"
> + - reg: spi chip select number for the device
> + - vref-supply: The regulator supply for ADC reference voltage
> + - spi-max-frequency: Max SPI frequency to use (< 400000)
> +
> +Example:
> +adc@0 {
> +	compatible = "ti,adc0832";
> +	reg = <0>;
> +	vref-supply = <&vdd_supply>;
> +	spi-max-frequency = <200000>;
> +};
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index b8f5218..cc53003 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -333,6 +333,16 @@ config TI_ADC081C
>  	  This driver can also be built as a module. If so, the module will be
>  	  called ti-adc081c.
>  
> +config TI_ADC0832
> +	tristate "Texas Instruments ADC0831/ADC0832/ADC0834/ADC0838"
> +	depends on SPI
> +	help
> +	  If you say yes here you get support for Texas Instruments ADC0831,
> +	  ADC0832, ADC0834, ADC0838 ADC chips.
> +
> +	  This driver can also be built as a module. If so, the module will be
> +	  called ti-adc0832.
> +
>  config TI_ADC128S052
>  	tristate "Texas Instruments ADC128S052/ADC122S021"
>  	depends on SPI
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 3f63a89..706921c 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -32,6 +32,7 @@ obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
>  obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
>  obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
>  obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
> +obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
>  obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
>  obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
>  obj-$(CONFIG_TWL4030_MADC) += twl4030-madc.o
> diff --git a/drivers/iio/adc/ti-adc0832.c b/drivers/iio/adc/ti-adc0832.c
> new file mode 100644
> index 0000000..0afeac0
> --- /dev/null
> +++ b/drivers/iio/adc/ti-adc0832.c
> @@ -0,0 +1,288 @@
> +/*
> + * ADC0831/ADC0832/ADC0834/ADC0838 8-bit ADC driver
> + *
> + * Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
> + *
> + * This file is subject to the terms and conditions of version 2 of
> + * the GNU General Public License.  See the file COPYING in the main
> + * directory of this archive for more details.
> + *
> + * Datasheet: http://www.ti.com/lit/ds/symlink/adc0832-n.pdf
> + */
> +
> +#include <linux/module.h>
> +#include <linux/spi/spi.h>
> +#include <linux/iio/iio.h>
> +#include <linux/regulator/consumer.h>
> +
> +enum {
> +	adc0831,
> +	adc0832,
> +	adc0834,
> +	adc0838,
> +};
> +
> +struct adc0832 {
> +	struct spi_device *spi;
> +	struct regulator *reg;
> +	struct mutex lock;
> +	u8 mux_bits;
> +
> +	u8 tx_buf[2] ____cacheline_aligned;
> +	u8 rx_buf[2];
> +};
> +
> +#define ADC0832_VOLTAGE_CHANNEL(chan)					\
> +	{								\
> +		.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 ADC0832_VOLTAGE_CHANNEL_DIFF(chan1, chan2)			\
> +	{								\
> +		.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 adc0831_channels[] = {
> +	ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1),
> +};
> +
> +static const struct iio_chan_spec adc0832_channels[] = {
> +	ADC0832_VOLTAGE_CHANNEL(0),
> +	ADC0832_VOLTAGE_CHANNEL(1),
> +	ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1),
> +	ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0),
> +};
> +
> +static const struct iio_chan_spec adc0834_channels[] = {
> +	ADC0832_VOLTAGE_CHANNEL(0),
> +	ADC0832_VOLTAGE_CHANNEL(1),
> +	ADC0832_VOLTAGE_CHANNEL(2),
> +	ADC0832_VOLTAGE_CHANNEL(3),
> +	ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1),
> +	ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0),
> +	ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3),
> +	ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2),
> +};
> +
> +static const struct iio_chan_spec adc0838_channels[] = {
> +	ADC0832_VOLTAGE_CHANNEL(0),
> +	ADC0832_VOLTAGE_CHANNEL(1),
> +	ADC0832_VOLTAGE_CHANNEL(2),
> +	ADC0832_VOLTAGE_CHANNEL(3),
> +	ADC0832_VOLTAGE_CHANNEL(4),
> +	ADC0832_VOLTAGE_CHANNEL(5),
> +	ADC0832_VOLTAGE_CHANNEL(6),
> +	ADC0832_VOLTAGE_CHANNEL(7),
> +	ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1),
> +	ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0),
> +	ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3),
> +	ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2),
> +	ADC0832_VOLTAGE_CHANNEL_DIFF(4, 5),
> +	ADC0832_VOLTAGE_CHANNEL_DIFF(5, 4),
> +	ADC0832_VOLTAGE_CHANNEL_DIFF(6, 7),
> +	ADC0832_VOLTAGE_CHANNEL_DIFF(7, 6),
> +};
> +
> +static int adc0831_adc_conversion(struct adc0832 *adc)
> +{
> +	struct spi_device *spi = adc->spi;
> +	int ret;
> +
> +	ret = spi_read(spi, &adc->rx_buf, 2);
> +	if (ret)
> +		return ret;
> +
> +	/*
> +	 * Skip TRI-STATE and a leading zero
> +	 */
> +	return (adc->rx_buf[0] << 2 & 0xff) | (adc->rx_buf[1] >> 6);
> +}
> +
> +static int adc0832_adc_conversion(struct adc0832 *adc, int channel,
> +				bool differential)
> +{
> +	struct spi_device *spi = adc->spi;
> +	struct spi_transfer xfer = {
> +		.tx_buf = adc->tx_buf,
> +		.rx_buf = adc->rx_buf,
> +		.len = 2,
> +	};
> +	int ret;
> +
> +	if (!adc->mux_bits)
> +		return adc0831_adc_conversion(adc);
> +
> +	/* start bit */
> +	adc->tx_buf[0] = 1 << (adc->mux_bits + 1);
> +	/* single-ended or differential */
> +	adc->tx_buf[0] |= differential ? 0 : (1 << adc->mux_bits);
> +	/* odd / sign */
> +	adc->tx_buf[0] |= (channel % 2) << (adc->mux_bits - 1);
> +	/* select */
> +	if (adc->mux_bits > 1)
> +		adc->tx_buf[0] |= channel / 2;
> +
> +	/* align Data output BIT7 (MSB) to 8-bit boundary */
> +	adc->tx_buf[0] <<= 1;
> +
> +	ret = spi_sync_transfer(spi, &xfer, 1);
> +	if (ret)
> +		return ret;
> +
> +	return adc->rx_buf[1];
> +}
> +
> +static int adc0832_read_raw(struct iio_dev *iio,
> +			struct iio_chan_spec const *channel, int *value,
> +			int *shift, long mask)
> +{
> +	struct adc0832 *adc = iio_priv(iio);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		mutex_lock(&adc->lock);
> +		*value = adc0832_adc_conversion(adc, channel->channel,
> +						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 = 8;
> +
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info adc0832_info = {
> +	.read_raw = adc0832_read_raw,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +static int adc0832_probe(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev;
> +	struct adc0832 *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 = spi_get_device_id(spi)->name;
> +	indio_dev->dev.parent = &spi->dev;
> +	indio_dev->info = &adc0832_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	switch (spi_get_device_id(spi)->driver_data) {
> +	case adc0831:
> +		adc->mux_bits = 0;
> +		indio_dev->channels = adc0831_channels;
> +		indio_dev->num_channels = ARRAY_SIZE(adc0831_channels);
> +		break;
> +	case adc0832:
> +		adc->mux_bits = 1;
> +		indio_dev->channels = adc0832_channels;
> +		indio_dev->num_channels = ARRAY_SIZE(adc0832_channels);
> +		break;
> +	case adc0834:
> +		adc->mux_bits = 2;
> +		indio_dev->channels = adc0834_channels;
> +		indio_dev->num_channels = ARRAY_SIZE(adc0834_channels);
> +		break;
> +	case adc0838:
> +		adc->mux_bits = 3;
> +		indio_dev->channels = adc0838_channels;
> +		indio_dev->num_channels = ARRAY_SIZE(adc0838_channels);
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	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;
> +}
> +
> +static int adc0832_remove(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> +	struct adc0832 *adc = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +	regulator_disable(adc->reg);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_OF
> +
> +static const struct of_device_id adc0832_dt_ids[] = {
> +	{ .compatible = "ti,adc0831", },
> +	{ .compatible = "ti,adc0832", },
> +	{ .compatible = "ti,adc0834", },
> +	{ .compatible = "ti,adc0838", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, adc0832_dt_ids);
> +
> +#endif
> +
> +static const struct spi_device_id adc0832_id[] = {
> +	{ "adc0831", adc0831 },
> +	{ "adc0832", adc0832 },
> +	{ "adc0834", adc0834 },
> +	{ "adc0838", adc0838 },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(spi, adc0832_id);
> +
> +static struct spi_driver adc0832_driver = {
> +	.driver = {
> +		.name = "adc0832",
> +		.of_match_table = of_match_ptr(adc0832_dt_ids),
> +	},
> +	.probe = adc0832_probe,
> +	.remove = adc0832_remove,
> +	.id_table = adc0832_id,
> +};
> +module_spi_driver(adc0832_driver);
> +
> +MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
> +MODULE_DESCRIPTION("ADC0831/ADC0832/ADC0834/ADC0838 driver");
> +MODULE_LICENSE("GPL v2");
>