diff options
Diffstat (limited to 'drivers/iio/adc/ti-ads8344.c')
| -rw-r--r-- | drivers/iio/adc/ti-ads8344.c | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/drivers/iio/adc/ti-ads8344.c b/drivers/iio/adc/ti-ads8344.c new file mode 100644 index 000000000..a345a30d7 --- /dev/null +++ b/drivers/iio/adc/ti-ads8344.c @@ -0,0 +1,204 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * ADS8344 16-bit 8-Channel ADC driver + * + * Author: Gregory CLEMENT <gregory.clement@bootlin.com> + * + * Datasheet: https://www.ti.com/lit/ds/symlink/ads8344.pdf + */ + +#include <linux/delay.h> +#include <linux/iio/buffer.h> +#include <linux/iio/iio.h> +#include <linux/module.h> +#include <linux/regulator/consumer.h> +#include <linux/spi/spi.h> + +#define ADS8344_START BIT(7) +#define ADS8344_SINGLE_END BIT(2) +#define ADS8344_CHANNEL(channel) ((channel) << 4) +#define ADS8344_CLOCK_INTERNAL 0x2 /* PD1 = 1 and PD0 = 0 */ + +struct ads8344 { + struct spi_device *spi; + struct regulator *reg; + /* + * Lock protecting access to adc->tx_buff and rx_buff, + * especially from concurrent read on sysfs file. + */ + struct mutex lock; + + u8 tx_buf ____cacheline_aligned; + u8 rx_buf[3]; +}; + +#define ADS8344_VOLTAGE_CHANNEL(chan, addr) \ + { \ + .type = IIO_VOLTAGE, \ + .indexed = 1, \ + .channel = chan, \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ + .address = addr, \ + } + +#define ADS8344_VOLTAGE_CHANNEL_DIFF(chan1, chan2, addr) \ + { \ + .type = IIO_VOLTAGE, \ + .indexed = 1, \ + .channel = (chan1), \ + .channel2 = (chan2), \ + .differential = 1, \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ + .address = addr, \ + } + +static const struct iio_chan_spec ads8344_channels[] = { + ADS8344_VOLTAGE_CHANNEL(0, 0), + ADS8344_VOLTAGE_CHANNEL(1, 4), + ADS8344_VOLTAGE_CHANNEL(2, 1), + ADS8344_VOLTAGE_CHANNEL(3, 5), + ADS8344_VOLTAGE_CHANNEL(4, 2), + ADS8344_VOLTAGE_CHANNEL(5, 6), + ADS8344_VOLTAGE_CHANNEL(6, 3), + ADS8344_VOLTAGE_CHANNEL(7, 7), + ADS8344_VOLTAGE_CHANNEL_DIFF(0, 1, 8), + ADS8344_VOLTAGE_CHANNEL_DIFF(2, 3, 9), + ADS8344_VOLTAGE_CHANNEL_DIFF(4, 5, 10), + ADS8344_VOLTAGE_CHANNEL_DIFF(6, 7, 11), + ADS8344_VOLTAGE_CHANNEL_DIFF(1, 0, 12), + ADS8344_VOLTAGE_CHANNEL_DIFF(3, 2, 13), + ADS8344_VOLTAGE_CHANNEL_DIFF(5, 4, 14), + ADS8344_VOLTAGE_CHANNEL_DIFF(7, 6, 15), +}; + +static int ads8344_adc_conversion(struct ads8344 *adc, int channel, + bool differential) +{ + struct spi_device *spi = adc->spi; + int ret; + + adc->tx_buf = ADS8344_START; + if (!differential) + adc->tx_buf |= ADS8344_SINGLE_END; + adc->tx_buf |= ADS8344_CHANNEL(channel); + adc->tx_buf |= ADS8344_CLOCK_INTERNAL; + + ret = spi_write(spi, &adc->tx_buf, 1); + if (ret) + return ret; + + udelay(9); + + ret = spi_read(spi, adc->rx_buf, sizeof(adc->rx_buf)); + if (ret) + return ret; + + return adc->rx_buf[0] << 9 | adc->rx_buf[1] << 1 | adc->rx_buf[2] >> 7; +} + +static int ads8344_read_raw(struct iio_dev *iio, + struct iio_chan_spec const *channel, int *value, + int *shift, long mask) +{ + struct ads8344 *adc = iio_priv(iio); + + switch (mask) { + case IIO_CHAN_INFO_RAW: + mutex_lock(&adc->lock); + *value = ads8344_adc_conversion(adc, channel->address, + channel->differential); + mutex_unlock(&adc->lock); + if (*value < 0) + return *value; + + return IIO_VAL_INT; + case IIO_CHAN_INFO_SCALE: + *value = regulator_get_voltage(adc->reg); + if (*value < 0) + return *value; + + /* convert regulator output voltage to mV */ + *value /= 1000; + *shift = 16; + + return IIO_VAL_FRACTIONAL_LOG2; + default: + return -EINVAL; + } +} + +static const struct iio_info ads8344_info = { + .read_raw = ads8344_read_raw, +}; + +static int ads8344_probe(struct spi_device *spi) +{ + struct iio_dev *indio_dev; + struct ads8344 *adc; + int ret; + + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc)); + if (!indio_dev) + return -ENOMEM; + + adc = iio_priv(indio_dev); + adc->spi = spi; + mutex_init(&adc->lock); + + indio_dev->name = dev_name(&spi->dev); + indio_dev->info = &ads8344_info; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = ads8344_channels; + indio_dev->num_channels = ARRAY_SIZE(ads8344_channels); + + adc->reg = devm_regulator_get(&spi->dev, "vref"); + if (IS_ERR(adc->reg)) + return PTR_ERR(adc->reg); + + ret = regulator_enable(adc->reg); + if (ret) + return ret; + + spi_set_drvdata(spi, indio_dev); + + ret = iio_device_register(indio_dev); + if (ret) { + regulator_disable(adc->reg); + return ret; + } + + return 0; +} + +static int ads8344_remove(struct spi_device *spi) +{ + struct iio_dev *indio_dev = spi_get_drvdata(spi); + struct ads8344 *adc = iio_priv(indio_dev); + + iio_device_unregister(indio_dev); + regulator_disable(adc->reg); + + return 0; +} + +static const struct of_device_id ads8344_of_match[] = { + { .compatible = "ti,ads8344", }, + {} +}; +MODULE_DEVICE_TABLE(of, ads8344_of_match); + +static struct spi_driver ads8344_driver = { + .driver = { + .name = "ads8344", + .of_match_table = ads8344_of_match, + }, + .probe = ads8344_probe, + .remove = ads8344_remove, +}; +module_spi_driver(ads8344_driver); + +MODULE_AUTHOR("Gregory CLEMENT <gregory.clement@bootlin.com>"); +MODULE_DESCRIPTION("ADS8344 driver"); +MODULE_LICENSE("GPL"); |