[PATCH 2/2] iio: adc: Add driver for the TI ADS8344 A/DC chips

Gregory CLEMENT
2019-03-15T15:12:07Z

This adds support for the Texas Instruments ADS8344 ADC chip. This chip
has a 16-bit 8-Channel ADC and is access directly through SPI.

Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
---
drivers/iio/adc/Kconfig | 10 ++
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/ti-ads8344.c | 216 +++++++++++++++++++++++++++++++++++
3 files changed, 227 insertions(+)
create mode 100644 drivers/iio/adc/ti-ads8344.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 76db6e5cc296..447d3a871746 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -967,6 +967,16 @@ config TI_ADS7950
To compile this driver as a module, choose M here: the
module will be called ti-ads7950.

+config TI_ADS8344
+ tristate "Texas Instruments ADS8344"
+ depends on SPI && OF
+ help
+ If you say yes here you get support for Texas Instruments ADS8344
+ ADC chips
+
+ This driver can also be built as a module. If so, the module will be
+ called ti-ads8344.
+
config TI_ADS8688
tristate "Texas Instruments ADS8688"
depends on SPI && OF
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 6fcebd167524..1f3ae934111d 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -87,6 +87,7 @@ obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
obj-$(CONFIG_TI_ADC161S626) += ti-adc161s626.o
obj-$(CONFIG_TI_ADS1015) += ti-ads1015.o
obj-$(CONFIG_TI_ADS7950) += ti-ads7950.o
+obj-$(CONFIG_TI_ADS8344) += ti-ads8344.o
obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
obj-$(CONFIG_TI_ADS124S08) += ti-ads124s08.o
obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
diff --git a/drivers/iio/adc/ti-ads8344.c b/drivers/iio/adc/ti-ads8344.c
new file mode 100644
index 000000000000..6159d8518871
--- /dev/null
+++ b/drivers/iio/adc/ti-ads8344.c
@@ -0,0 +1,216 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * ADS8344 16-bit 8-Channel ADC driver
+ *
+ * Author: Gregory CLEMENT <gregory.clement@bootlin.com>
+ *
+ * Datasheet: http://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>
+
+struct ads8344 {
+ struct spi_device *spi;
+ struct regulator *reg;
+ struct mutex lock;
+
+ u8 tx_buf ____cacheline_aligned;
+ u16 rx_buf;
+};
+
+#define ADS8344_VOLTAGE_CHANNEL(chan, si) \
+ { \
+ .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), \
+ .scan_index = si, \
+ .scan_type = { \
+ .sign = 'u', \
+ .realbits = 16, \
+ .storagebits = 16, \
+ }, \
+ }
+
+#define ADS8344_VOLTAGE_CHANNEL_DIFF(chan1, chan2, si) \
+ { \
+ .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), \
+ .scan_index = si, \
+ .scan_type = { \
+ .sign = 'u', \
+ .realbits = 16, \
+ .storagebits = 16, \
+ }, \
+ }
+
+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;
+
+ /* start bit */
+ adc->tx_buf = BIT(7);
+ /* single-ended or differential */
+ adc->tx_buf |= differential ? 0 : BIT(2);
+ /* select channel(s) */
+ adc->tx_buf |= channel << 4;
+ /* internal clock mode */
+ adc->tx_buf |= 0x2;
+
+ ret = spi_write(spi, &adc->tx_buf, 1);
+ if (ret)
+ return ret;
+
+ udelay(9);
+
+ ret = spi_read(spi, &adc->rx_buf, 2);
+ if (ret)
+ return ret;
+
+ return adc->rx_buf;
+}
+
+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->scan_index,
+ 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->dev.parent = &spi->dev;
+ indio_dev->dev.of_node = spi->dev.of_node;
+ 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)
+ goto err_buffer_cleanup;
+
+ return 0;
+err_buffer_cleanup:
+ regulator_disable(adc->reg);
+
+ return ret;
+}
+
+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;
+}
+
+#ifdef CONFIG_OF
+
+static const struct of_device_id ads8344_dt_ids[] = {
+ { .compatible = "ti,ads8344", },
+ {}
+};
+MODULE_DEVICE_TABLE(of, ads8344_dt_ids);
+
+#endif
+
+static struct spi_driver ads8344_driver = {
+ .driver = {
+ .name = "ads8344",
+ .of_match_table = of_match_ptr(ads8344_dt_ids),
+ },
+ .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 v2");
--
2.20.1