| // 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"); |