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