[PATCH v6 06/13] IIO: ADC: add sigma delta modulator support

[Jonathan Cameron]

On Fri, 1 Dec 2017 18:40:13 +0100
Arnaud Pouliquen <arnaud.pouliquen at st.com> wrote:

> Add generic driver to support sigma delta modulators.
> Typically, this device is hardware connected to
> an IIO device in charge of the conversion. Devices are
> bonded through the hardware consumer API.
> 
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen at st.com>
I love this little one ;) Smallest IIO driver yet!
Doesn't technically 'do' anything but that's not the point.

Acked-by: Jonathan Cameron <Jonathan.Cameron at huawei.com>

> ---
>  drivers/iio/adc/Kconfig            | 12 ++++++
>  drivers/iio/adc/Makefile           |  1 +
>  drivers/iio/adc/sd_adc_modulator.c | 81 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 94 insertions(+)
>  create mode 100644 drivers/iio/adc/sd_adc_modulator.c
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 5762565..c5db62f 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -626,6 +626,18 @@ config SPEAR_ADC
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called spear_adc.
>  
> +config SD_ADC_MODULATOR
> +	tristate "Generic sigma delta modulator"
> +	depends on OF
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
> +	help
> +	  Select this option to enables sigma delta modulator. This driver can
> +	  support generic sigma delta modulators.
> +
> +	  This driver can also be built as a module.  If so, the module
> +	  will be called sd_adc_modulator.
> +
>  config STM32_ADC_CORE
>  	tristate "STMicroelectronics STM32 adc core"
>  	depends on ARCH_STM32 || COMPILE_TEST
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 9874e05..d800325 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -81,3 +81,4 @@ obj-$(CONFIG_VF610_ADC) += vf610_adc.o
>  obj-$(CONFIG_VIPERBOARD_ADC) += viperboard_adc.o
>  xilinx-xadc-y := xilinx-xadc-core.o xilinx-xadc-events.o
>  obj-$(CONFIG_XILINX_XADC) += xilinx-xadc.o
> +obj-$(CONFIG_SD_ADC_MODULATOR) += sd_adc_modulator.o
> diff --git a/drivers/iio/adc/sd_adc_modulator.c b/drivers/iio/adc/sd_adc_modulator.c
> new file mode 100644
> index 0000000..08bd7b6
> --- /dev/null
> +++ b/drivers/iio/adc/sd_adc_modulator.c
> @@ -0,0 +1,81 @@
> +/*
> + * Generic sigma delta modulator driver
> + *
> + * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
> + * Author: Arnaud Pouliquen <arnaud.pouliquen at st.com>.
> + *
> + * License type: GPLv2
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published by
> + * the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful, but
> + * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
> + * or FITNESS FOR A PARTICULAR PURPOSE.
> + * See the GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program. If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/triggered_buffer.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +
> +static const struct iio_info iio_sd_mod_iio_info;
> +
> +static const struct iio_chan_spec iio_sd_mod_ch = {
> +	.type = IIO_VOLTAGE,
> +	.indexed = 1,
> +	.scan_type = {
> +		.sign = 'u',
> +		.realbits = 1,
> +		.shift = 0,
> +	},
> +};
> +
> +static int iio_sd_mod_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct iio_dev *iio;
> +
> +	iio = devm_iio_device_alloc(dev, 0);
> +	if (!iio)
> +		return -ENOMEM;
> +
> +	iio->dev.parent = dev;
> +	iio->dev.of_node = dev->of_node;
> +	iio->name = dev_name(dev);
> +	iio->info = &iio_sd_mod_iio_info;
> +	iio->modes = INDIO_BUFFER_HARDWARE;
> +
> +	iio->num_channels = 1;
> +	iio->channels = &iio_sd_mod_ch;
> +
> +	platform_set_drvdata(pdev, iio);
> +
> +	return devm_iio_device_register(&pdev->dev, iio);
> +}
> +
> +static const struct of_device_id sd_adc_of_match[] = {
> +	{ .compatible = "sd-modulator" },
> +	{ .compatible = "ads1201" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, sd_adc_of_match);
> +
> +static struct platform_driver iio_sd_mod_adc = {
> +	.driver = {
> +		.name = "iio_sd_adc_mod",
> +		.of_match_table = of_match_ptr(sd_adc_of_match),
> +	},
> +	.probe = iio_sd_mod_probe,
> +};
> +
> +module_platform_driver(iio_sd_mod_adc);
> +
> +MODULE_DESCRIPTION("Basic sigma delta modulator");
> +MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen at st.com>");
> +MODULE_LICENSE("GPL v2");