> Add IIO driver for Maxim MAX11100 single-channel ADC.
> Add DT bindings documentation.
some more comments
> Signed-off-by: Jacopo Mondi <jacopo@xxxxxxxxxx>
> ---
>
> v1 -> v2:
> - incorporated pmeerw's review comments
> - retrieve vref from dts and use that to convert read_raw result
> to mV
> - add device tree bindings documentation
>
> ---
> .../devicetree/bindings/iio/adc/max11100.txt | 17 +++
> drivers/iio/adc/Kconfig | 9 ++
> drivers/iio/adc/Makefile | 1 +
> drivers/iio/adc/max11100.c | 166 +++++++++++++++++++++
> 4 files changed, 193 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/iio/adc/max11100.txt
> create mode 100644 drivers/iio/adc/max11100.c
>
> diff --git a/Documentation/devicetree/bindings/iio/adc/max11100.txt b/Documentation/devicetree/bindings/iio/adc/max11100.txt
> new file mode 100644
> index 0000000..6877c11
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/max11100.txt
> @@ -0,0 +1,17 @@
> +* Maxim max11100 Analog to Digital Converter (ADC)
> +
> +Required properties:
> + - compatible: Should be "maxim,max11100"
> + - vref-supply: phandle to the regulator that provides reference voltage
> +
> +Optional properties:
> + - spi-max-frequency: SPI maximum frequency
> +
> +Example:
> +
> +adc0: max11100@0 {
> + compatible = "maxim,max11100";
> + vref-supply = <&adc0_vref>;
> + spi-max-frequency = <240000>;
> +};
> +
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 99c0514..a909484 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -285,6 +285,15 @@ config MAX1027
> To compile this driver as a module, choose M here: the module will be
> called max1027.
>
> +config MAX11100
> + tristate "Maxim max11100 ADC driver"
> + depends on SPI
SPI_MASTER is more precise I think
> + help
> + Say yes here to build support for Maxim max11100 SPI ADC
> +
> + To compile this driver as a module, choose M here: the module will be
> + called max11100.
> +
> config MAX1363
> tristate "Maxim max1363 ADC driver"
> depends on I2C
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 7a40c04..1463044 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -29,6 +29,7 @@ obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
> obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o
> obj-$(CONFIG_LTC2485) += ltc2485.o
> obj-$(CONFIG_MAX1027) += max1027.o
> +obj-$(CONFIG_MAX11100) += max11100.o
> obj-$(CONFIG_MAX1363) += max1363.o
> obj-$(CONFIG_MCP320X) += mcp320x.o
> obj-$(CONFIG_MCP3422) += mcp3422.o
> diff --git a/drivers/iio/adc/max11100.c b/drivers/iio/adc/max11100.c
> new file mode 100644
> index 0000000..f372ad8
> --- /dev/null
> +++ b/drivers/iio/adc/max11100.c
> @@ -0,0 +1,166 @@
> +/*
> + * iio/adc/max11100.c
> + * Maxim max11100 ADC Driver with IIO interface
> + *
> + * Copyright (C) 2016 Renesas Electronics Corporation
> + * Copyright (C) 2016 Jacopo Mondi
> + *
> + * 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.
> + */
> +#include <linux/delay.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/spi/spi.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/driver.h>
> +
> +/*
> + * LSB is the ADC single digital step
> + * 1 LSB = (vref / 2 ^ 16)
> + * AIN = (DIN * LSB)
> + */
> +#define MAX11100_LSB_DIV (1 << 16)
> +#define MAX11100_LSB(vref) (vref / MAX11100_LSB_DIV)
maybe parenthesis around vref
> +
> +struct max11100_state {
> + const struct max11100_chip_desc *desc;
> + struct spi_device *spi;
> + int vref_uv;
> + struct mutex lock;
> +};
> +
> +static struct iio_chan_spec max11100_channels[] = {
> + { /* [0] */
> + .type = IIO_VOLTAGE,
> + .scan_type = {
scan_type not needed since driver does not support buffered reads
> + .sign = 'u',
> + .realbits = 16,
> + .storagebits = 24,
> + .shift = 8,
> + .repeat = 1,
> + .endianness = IIO_BE,
> + },
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> + },
> +};
> +
> +static struct max11100_chip_desc {
> + unsigned int num_chan;
> + const struct iio_chan_spec *channels;
> +} max11100_desc = {
> + .num_chan = ARRAY_SIZE(max11100_channels),
> + .channels = max11100_channels,
> +};
> +
> +static int max11100_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + int ret;
> + struct max11100_state *state = iio_priv(indio_dev);
> + uint8_t buffer[3];
> +
> + mutex_lock(&state->lock);
> +
> + ret = spi_read(state->spi, buffer, sizeof(buffer));
> + if (ret) {
> + mutex_unlock(&state->lock);
> + dev_err(&indio_dev->dev, "SPI transfer failed\n");
> + return ret;
> + }
> + mutex_unlock(&state->lock);
> +
> + /* the first 8 bits sent out from ADC must be 0s */
> + if (buffer[0]) {
> + dev_err(&indio_dev->dev, "Invalid value: buffer[0] != 0\n");
> + return -EINVAL;
> + }
> +
> + *val = be16_to_cpu(*(uint16_t *)&buffer[1]);
> + *val = *val * MAX11100_LSB(state->vref_uv) / 1000;
no, INFO_RAW shall not perform such scaling, use _PROCESSED or add an
INFO_SCALE to indicate the scaling
> +
> + return IIO_VAL_INT;
> +}
> +
> +static const struct iio_info max11100_info = {
> + .driver_module = THIS_MODULE,
> + .read_raw = max11100_read_raw,
> +};
> +
> +static int max11100_probe(struct spi_device *spi)
> +{
> + int ret;
> + struct iio_dev *indio_dev;
> + struct regulator *vref_reg;
> + struct max11100_state *state;
> +
> + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + spi_set_drvdata(spi, indio_dev);
> +
> + state = iio_priv(indio_dev);
> + state->spi = spi;
> + state->desc = &max11100_desc;
> +
> + mutex_init(&state->lock);
> +
> + indio_dev->dev.parent = &spi->dev;
> + indio_dev->dev.of_node = spi->dev.of_node;
> + indio_dev->info = &max11100_info;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->channels = state->desc->channels;
> + indio_dev->num_channels = state->desc->num_chan;
> +
> + vref_reg = devm_regulator_get(&spi->dev, "vref");
> + if (IS_ERR(vref_reg))
> + return PTR_ERR(vref_reg);
> +
> + ret = regulator_enable(vref_reg);
> + if (ret)
> + return ret;
> +
> + state->vref_uv = regulator_get_voltage(vref_reg);
> + if (state->vref_uv < 0) {
> + /* dummy regulator "get_voltage" returns -EINVAL as well */
> + ret = -EINVAL;
> + goto disable_regulator;
> + }
> +
> + ret = devm_iio_device_register(&spi->dev, indio_dev);
the regulator needs to be disabled in a _remove() function and since you
need a remove function, devm_iio_device_register() should not be used
> + if (ret)
> + goto disable_regulator;
> +
> + return 0;
> +
> +disable_regulator:
> + regulator_disable(vref_reg);
> + return ret;
> +}
> +
> +static const struct of_device_id max11100_ids[] = {
> + {.compatible = "maxim,max11100"},
> + { },
> +};
> +MODULE_DEVICE_TABLE(of, max11100_ids);
> +
> +static struct spi_driver max11100_driver = {
> + .driver = {
> + .name = "max11100",
> + .owner = THIS_MODULE,
> + .of_match_table = of_match_ptr(max11100_ids),
> + },
> + .probe = max11100_probe,
> +};
> +
> +module_spi_driver(max11100_driver);
> +
> +MODULE_AUTHOR("Jacopo Mondi <jacopo@xxxxxxxxxx>");
> +MODULE_DESCRIPTION("Maxim max11100 ADC Driver");
> +MODULE_LICENSE("GPL v2");
>
--
Peter Meerwald-Stadler
+43-664-2444418 (mobile)
