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- // 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");
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