diff options
Diffstat (limited to 'drivers/iio/adc/max11100.c')
| -rw-r--r-- | drivers/iio/adc/max11100.c | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/drivers/iio/adc/max11100.c b/drivers/iio/adc/max11100.c new file mode 100644 index 000000000000..b738ecf1b234 --- /dev/null +++ b/drivers/iio/adc/max11100.c @@ -0,0 +1,192 @@ +/* + * iio/adc/max11100.c + * Maxim max11100 ADC Driver with IIO interface + * + * Copyright (C) 2016-17 Renesas Electronics Corporation + * Copyright (C) 2016-17 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/driver.h> + +/* + * LSB is the ADC single digital step + * 1 LSB = (vref_mv / 2 ^ 16) + * + * LSB is used to calculate analog voltage value + * from the number of ADC steps count + * + * Ain = (count * LSB) + */ +#define MAX11100_LSB_DIV (1 << 16) + +struct max11100_state { + const struct max11100_chip_desc *desc; + struct regulator *vref_reg; + struct spi_device *spi; + + /* + * DMA (thus cache coherency maintenance) requires the + * transfer buffers to live in their own cache lines. + */ + u8 buffer[3] ____cacheline_aligned; +}; + +static struct iio_chan_spec max11100_channels[] = { + { /* [0] */ + .type = IIO_VOLTAGE, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | + BIT(IIO_CHAN_INFO_SCALE), + }, +}; + +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_single(struct iio_dev *indio_dev, int *val) +{ + int ret; + struct max11100_state *state = iio_priv(indio_dev); + + ret = spi_read(state->spi, state->buffer, sizeof(state->buffer)); + if (ret) { + dev_err(&indio_dev->dev, "SPI transfer failed\n"); + return ret; + } + + /* the first 8 bits sent out from ADC must be 0s */ + if (state->buffer[0]) { + dev_err(&indio_dev->dev, "Invalid value: buffer[0] != 0\n"); + return -EINVAL; + } + + *val = (state->buffer[1] << 8) | state->buffer[2]; + + return 0; +} + +static int max11100_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long info) +{ + int ret, vref_uv; + struct max11100_state *state = iio_priv(indio_dev); + + switch (info) { + case IIO_CHAN_INFO_RAW: + ret = max11100_read_single(indio_dev, val); + if (ret) + return ret; + + return IIO_VAL_INT; + + case IIO_CHAN_INFO_SCALE: + vref_uv = regulator_get_voltage(state->vref_reg); + if (vref_uv < 0) + /* dummy regulator "get_voltage" returns -EINVAL */ + return -EINVAL; + + *val = vref_uv / 1000; + *val2 = MAX11100_LSB_DIV; + return IIO_VAL_FRACTIONAL; + } + + return -EINVAL; +} + +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 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; + + indio_dev->dev.parent = &spi->dev; + indio_dev->dev.of_node = spi->dev.of_node; + indio_dev->name = "max11100"; + 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; + + state->vref_reg = devm_regulator_get(&spi->dev, "vref"); + if (IS_ERR(state->vref_reg)) + return PTR_ERR(state->vref_reg); + + ret = regulator_enable(state->vref_reg); + if (ret) + return ret; + + ret = iio_device_register(indio_dev); + if (ret) + goto disable_regulator; + + return 0; + +disable_regulator: + regulator_disable(state->vref_reg); + + return ret; +} + +static int max11100_remove(struct spi_device *spi) +{ + struct iio_dev *indio_dev = spi_get_drvdata(spi); + struct max11100_state *state = iio_priv(indio_dev); + + regulator_disable(state->vref_reg); + + iio_device_unregister(indio_dev); + + return 0; +} + +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, + .remove = max11100_remove, +}; + +module_spi_driver(max11100_driver); + +MODULE_AUTHOR("Jacopo Mondi <jacopo@jmondi.org>"); +MODULE_DESCRIPTION("Maxim max11100 ADC Driver"); +MODULE_LICENSE("GPL v2"); |