Add IIO driver for Maxim MAX11100 single-channel ADC. Add DT bindings documentation.
Signed-off-by: Jacopo Mondi <[email protected]> --- 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 + 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) + +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 = { + .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; + + 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); + 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 <[email protected]>"); +MODULE_DESCRIPTION("Maxim max11100 ADC Driver"); +MODULE_LICENSE("GPL v2"); -- 2.7.4
