diff options
Diffstat (limited to 'drivers/iio/adc/ti-adc0832.c')
| -rw-r--r-- | drivers/iio/adc/ti-adc0832.c | 288 |
1 files changed, 288 insertions, 0 deletions
diff --git a/drivers/iio/adc/ti-adc0832.c b/drivers/iio/adc/ti-adc0832.c new file mode 100644 index 000000000000..0afeac0c9bad --- /dev/null +++ b/drivers/iio/adc/ti-adc0832.c @@ -0,0 +1,288 @@ +/* + * ADC0831/ADC0832/ADC0834/ADC0838 8-bit ADC driver + * + * Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com> + * + * This file is subject to the terms and conditions of version 2 of + * the GNU General Public License. See the file COPYING in the main + * directory of this archive for more details. + * + * Datasheet: http://www.ti.com/lit/ds/symlink/adc0832-n.pdf + */ + +#include <linux/module.h> +#include <linux/spi/spi.h> +#include <linux/iio/iio.h> +#include <linux/regulator/consumer.h> + +enum { + adc0831, + adc0832, + adc0834, + adc0838, +}; + +struct adc0832 { + struct spi_device *spi; + struct regulator *reg; + struct mutex lock; + u8 mux_bits; + + u8 tx_buf[2] ____cacheline_aligned; + u8 rx_buf[2]; +}; + +#define ADC0832_VOLTAGE_CHANNEL(chan) \ + { \ + .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) \ + } + +#define ADC0832_VOLTAGE_CHANNEL_DIFF(chan1, chan2) \ + { \ + .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) \ + } + +static const struct iio_chan_spec adc0831_channels[] = { + ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1), +}; + +static const struct iio_chan_spec adc0832_channels[] = { + ADC0832_VOLTAGE_CHANNEL(0), + ADC0832_VOLTAGE_CHANNEL(1), + ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1), + ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0), +}; + +static const struct iio_chan_spec adc0834_channels[] = { + ADC0832_VOLTAGE_CHANNEL(0), + ADC0832_VOLTAGE_CHANNEL(1), + ADC0832_VOLTAGE_CHANNEL(2), + ADC0832_VOLTAGE_CHANNEL(3), + ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1), + ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0), + ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3), + ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2), +}; + +static const struct iio_chan_spec adc0838_channels[] = { + ADC0832_VOLTAGE_CHANNEL(0), + ADC0832_VOLTAGE_CHANNEL(1), + ADC0832_VOLTAGE_CHANNEL(2), + ADC0832_VOLTAGE_CHANNEL(3), + ADC0832_VOLTAGE_CHANNEL(4), + ADC0832_VOLTAGE_CHANNEL(5), + ADC0832_VOLTAGE_CHANNEL(6), + ADC0832_VOLTAGE_CHANNEL(7), + ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1), + ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0), + ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3), + ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2), + ADC0832_VOLTAGE_CHANNEL_DIFF(4, 5), + ADC0832_VOLTAGE_CHANNEL_DIFF(5, 4), + ADC0832_VOLTAGE_CHANNEL_DIFF(6, 7), + ADC0832_VOLTAGE_CHANNEL_DIFF(7, 6), +}; + +static int adc0831_adc_conversion(struct adc0832 *adc) +{ + struct spi_device *spi = adc->spi; + int ret; + + ret = spi_read(spi, &adc->rx_buf, 2); + if (ret) + return ret; + + /* + * Skip TRI-STATE and a leading zero + */ + return (adc->rx_buf[0] << 2 & 0xff) | (adc->rx_buf[1] >> 6); +} + +static int adc0832_adc_conversion(struct adc0832 *adc, int channel, + bool differential) +{ + struct spi_device *spi = adc->spi; + struct spi_transfer xfer = { + .tx_buf = adc->tx_buf, + .rx_buf = adc->rx_buf, + .len = 2, + }; + int ret; + + if (!adc->mux_bits) + return adc0831_adc_conversion(adc); + + /* start bit */ + adc->tx_buf[0] = 1 << (adc->mux_bits + 1); + /* single-ended or differential */ + adc->tx_buf[0] |= differential ? 0 : (1 << adc->mux_bits); + /* odd / sign */ + adc->tx_buf[0] |= (channel % 2) << (adc->mux_bits - 1); + /* select */ + if (adc->mux_bits > 1) + adc->tx_buf[0] |= channel / 2; + + /* align Data output BIT7 (MSB) to 8-bit boundary */ + adc->tx_buf[0] <<= 1; + + ret = spi_sync_transfer(spi, &xfer, 1); + if (ret) + return ret; + + return adc->rx_buf[1]; +} + +static int adc0832_read_raw(struct iio_dev *iio, + struct iio_chan_spec const *channel, int *value, + int *shift, long mask) +{ + struct adc0832 *adc = iio_priv(iio); + + switch (mask) { + case IIO_CHAN_INFO_RAW: + mutex_lock(&adc->lock); + *value = adc0832_adc_conversion(adc, channel->channel, + 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 = 8; + + return IIO_VAL_FRACTIONAL_LOG2; + } + + return -EINVAL; +} + +static const struct iio_info adc0832_info = { + .read_raw = adc0832_read_raw, + .driver_module = THIS_MODULE, +}; + +static int adc0832_probe(struct spi_device *spi) +{ + struct iio_dev *indio_dev; + struct adc0832 *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 = spi_get_device_id(spi)->name; + indio_dev->dev.parent = &spi->dev; + indio_dev->info = &adc0832_info; + indio_dev->modes = INDIO_DIRECT_MODE; + + switch (spi_get_device_id(spi)->driver_data) { + case adc0831: + adc->mux_bits = 0; + indio_dev->channels = adc0831_channels; + indio_dev->num_channels = ARRAY_SIZE(adc0831_channels); + break; + case adc0832: + adc->mux_bits = 1; + indio_dev->channels = adc0832_channels; + indio_dev->num_channels = ARRAY_SIZE(adc0832_channels); + break; + case adc0834: + adc->mux_bits = 2; + indio_dev->channels = adc0834_channels; + indio_dev->num_channels = ARRAY_SIZE(adc0834_channels); + break; + case adc0838: + adc->mux_bits = 3; + indio_dev->channels = adc0838_channels; + indio_dev->num_channels = ARRAY_SIZE(adc0838_channels); + break; + default: + return -EINVAL; + } + + 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; +} + +static int adc0832_remove(struct spi_device *spi) +{ + struct iio_dev *indio_dev = spi_get_drvdata(spi); + struct adc0832 *adc = iio_priv(indio_dev); + + iio_device_unregister(indio_dev); + regulator_disable(adc->reg); + + return 0; +} + +#ifdef CONFIG_OF + +static const struct of_device_id adc0832_dt_ids[] = { + { .compatible = "ti,adc0831", }, + { .compatible = "ti,adc0832", }, + { .compatible = "ti,adc0834", }, + { .compatible = "ti,adc0838", }, + {} +}; +MODULE_DEVICE_TABLE(of, adc0832_dt_ids); + +#endif + +static const struct spi_device_id adc0832_id[] = { + { "adc0831", adc0831 }, + { "adc0832", adc0832 }, + { "adc0834", adc0834 }, + { "adc0838", adc0838 }, + {} +}; +MODULE_DEVICE_TABLE(spi, adc0832_id); + +static struct spi_driver adc0832_driver = { + .driver = { + .name = "adc0832", + .of_match_table = of_match_ptr(adc0832_dt_ids), + }, + .probe = adc0832_probe, + .remove = adc0832_remove, + .id_table = adc0832_id, +}; +module_spi_driver(adc0832_driver); + +MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>"); +MODULE_DESCRIPTION("ADC0831/ADC0832/ADC0834/ADC0838 driver"); +MODULE_LICENSE("GPL v2"); |