diff options
Diffstat (limited to 'drivers/iio/adc/max1241.c')
| -rw-r--r-- | drivers/iio/adc/max1241.c | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/drivers/iio/adc/max1241.c b/drivers/iio/adc/max1241.c new file mode 100644 index 000000000..a815ad1f6 --- /dev/null +++ b/drivers/iio/adc/max1241.c @@ -0,0 +1,223 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * MAX1241 low-power, 12-bit serial ADC + * + * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1240-MAX1241.pdf + */ + +#include <linux/delay.h> +#include <linux/gpio/consumer.h> +#include <linux/iio/iio.h> +#include <linux/module.h> +#include <linux/regulator/consumer.h> +#include <linux/spi/spi.h> + +#define MAX1241_VAL_MASK GENMASK(11, 0) +#define MAX1241_SHUTDOWN_DELAY_USEC 4 + +enum max1241_id { + max1241, +}; + +struct max1241 { + struct spi_device *spi; + struct mutex lock; + struct regulator *vdd; + struct regulator *vref; + struct gpio_desc *shutdown; + + __be16 data __aligned(IIO_DMA_MINALIGN); +}; + +static const struct iio_chan_spec max1241_channels[] = { + { + .type = IIO_VOLTAGE, + .indexed = 1, + .channel = 0, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | + BIT(IIO_CHAN_INFO_SCALE), + }, +}; + +static int max1241_read(struct max1241 *adc) +{ + struct spi_transfer xfers[] = { + /* + * Begin conversion by bringing /CS low for at least + * tconv us. + */ + { + .len = 0, + .delay.value = 8, + .delay.unit = SPI_DELAY_UNIT_USECS, + }, + /* + * Then read two bytes of data in our RX buffer. + */ + { + .rx_buf = &adc->data, + .len = 2, + }, + }; + + return spi_sync_transfer(adc->spi, xfers, ARRAY_SIZE(xfers)); +} + +static int max1241_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + int ret, vref_uV; + struct max1241 *adc = iio_priv(indio_dev); + + switch (mask) { + case IIO_CHAN_INFO_RAW: + mutex_lock(&adc->lock); + + if (adc->shutdown) { + gpiod_set_value(adc->shutdown, 0); + udelay(MAX1241_SHUTDOWN_DELAY_USEC); + ret = max1241_read(adc); + gpiod_set_value(adc->shutdown, 1); + } else + ret = max1241_read(adc); + + if (ret) { + mutex_unlock(&adc->lock); + return ret; + } + + *val = (be16_to_cpu(adc->data) >> 3) & MAX1241_VAL_MASK; + + mutex_unlock(&adc->lock); + return IIO_VAL_INT; + case IIO_CHAN_INFO_SCALE: + vref_uV = regulator_get_voltage(adc->vref); + + if (vref_uV < 0) + return vref_uV; + + *val = vref_uV / 1000; + *val2 = 12; + + return IIO_VAL_FRACTIONAL_LOG2; + default: + return -EINVAL; + } +} + +static const struct iio_info max1241_info = { + .read_raw = max1241_read_raw, +}; + +static void max1241_disable_vdd_action(void *data) +{ + struct max1241 *adc = data; + struct device *dev = &adc->spi->dev; + int err; + + err = regulator_disable(adc->vdd); + if (err) + dev_err(dev, "could not disable vdd regulator.\n"); +} + +static void max1241_disable_vref_action(void *data) +{ + struct max1241 *adc = data; + struct device *dev = &adc->spi->dev; + int err; + + err = regulator_disable(adc->vref); + if (err) + dev_err(dev, "could not disable vref regulator.\n"); +} + +static int max1241_probe(struct spi_device *spi) +{ + struct device *dev = &spi->dev; + struct iio_dev *indio_dev; + struct max1241 *adc; + int ret; + + indio_dev = devm_iio_device_alloc(dev, sizeof(*adc)); + if (!indio_dev) + return -ENOMEM; + + adc = iio_priv(indio_dev); + adc->spi = spi; + mutex_init(&adc->lock); + + adc->vdd = devm_regulator_get(dev, "vdd"); + if (IS_ERR(adc->vdd)) + return dev_err_probe(dev, PTR_ERR(adc->vdd), + "failed to get vdd regulator\n"); + + ret = regulator_enable(adc->vdd); + if (ret) + return ret; + + ret = devm_add_action_or_reset(dev, max1241_disable_vdd_action, adc); + if (ret) { + dev_err(dev, "could not set up vdd regulator cleanup action\n"); + return ret; + } + + adc->vref = devm_regulator_get(dev, "vref"); + if (IS_ERR(adc->vref)) + return dev_err_probe(dev, PTR_ERR(adc->vref), + "failed to get vref regulator\n"); + + ret = regulator_enable(adc->vref); + if (ret) + return ret; + + ret = devm_add_action_or_reset(dev, max1241_disable_vref_action, adc); + if (ret) { + dev_err(dev, "could not set up vref regulator cleanup action\n"); + return ret; + } + + adc->shutdown = devm_gpiod_get_optional(dev, "shutdown", + GPIOD_OUT_HIGH); + if (IS_ERR(adc->shutdown)) + return dev_err_probe(dev, PTR_ERR(adc->shutdown), + "cannot get shutdown gpio\n"); + + if (adc->shutdown) + dev_dbg(dev, "shutdown pin passed, low-power mode enabled"); + else + dev_dbg(dev, "no shutdown pin passed, low-power mode disabled"); + + indio_dev->name = spi_get_device_id(spi)->name; + indio_dev->info = &max1241_info; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = max1241_channels; + indio_dev->num_channels = ARRAY_SIZE(max1241_channels); + + return devm_iio_device_register(dev, indio_dev); +} + +static const struct spi_device_id max1241_id[] = { + { "max1241", max1241 }, + {} +}; + +static const struct of_device_id max1241_dt_ids[] = { + { .compatible = "maxim,max1241" }, + {} +}; +MODULE_DEVICE_TABLE(of, max1241_dt_ids); + +static struct spi_driver max1241_spi_driver = { + .driver = { + .name = "max1241", + .of_match_table = max1241_dt_ids, + }, + .probe = max1241_probe, + .id_table = max1241_id, +}; +module_spi_driver(max1241_spi_driver); + +MODULE_AUTHOR("Alexandru Lazar <alazar@startmail.com>"); +MODULE_DESCRIPTION("MAX1241 ADC driver"); +MODULE_LICENSE("GPL v2"); |