iio: adc: Add driver for the TI ADS8344 A/DC chips

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>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 160930889b2eaf2506c94cab78cc29886ce59a46..e3e068480ff7037f5d76772982dffcfa80c076a9 100644 (file)
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -979,6 +979,16 @@ 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 085a7512f8df726172c0069310356a3ce9c55e5f..ef9cc485fb67497b153aaa609ec2dbbd47c543b2 100644 (file)
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -88,6 +88,7 @@ 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 (file)
index 0000000..9a46080
--- /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: 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>
+
+#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;
+       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),   \
+       }
+
+#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),   \
+       }
+
+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, 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) {
+               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");