[PATCH v4 2/2] iio: adc: Add driver support for AD7292

Marcelo Schmitt
2019-11-08T13:56:59Z

The AD7292 is a 10-bit monitor and control system with ADC, DACs,
temperature sensor, and GPIOs.

Configure AD7292 devices in direct access mode, enabling single-ended
ADC readings.

Datasheet:
Link: https://www.analog.com/media/en/technical-documentation/data-sheets/ad7292.pdf

Signed-off-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com>
---
Changelog V3 -> V4:
- added brackets to shield macro parameters

MAINTAINERS | 1 +
drivers/iio/adc/Kconfig | 10 ++
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/ad7292.c | 350 +++++++++++++++++++++++++++++++++++++++
4 files changed, 362 insertions(+)
create mode 100644 drivers/iio/adc/ad7292.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 5d00e871c4c6..5941cfc0d6f7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -818,6 +818,7 @@ M: Marcelo Schmitt <marcelo.schmitt1@gmail.com>
L: linux-iio@vger.kernel.org
W: http://ez.analog.com/community/linux-device-drivers
S: Supported
+F: drivers/iio/adc/ad7292.c
F: Documentation/devicetree/bindings/iio/adc/adi,ad7292.yaml

ANALOG DEVICES INC AD7606 DRIVER
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 632b331429c6..02587c990cb5 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -59,6 +59,16 @@ config AD7291
To compile this driver as a module, choose M here: the
module will be called ad7291.

+config AD7292
+ tristate "Analog Devices AD7292 ADC driver"
+ depends on SPI
+ help
+ Say yes here to build support for Analog Devices AD7292
+ 8 Channel ADC with temperature sensor.
+
+ To compile this driver as a module, choose M here: the
+ module will be called ad7292.
+
config AD7298
tristate "Analog Devices AD7298 ADC driver"
depends on SPI
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 4779ab3ff8fb..1818f2f66566 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -11,6 +11,7 @@ obj-$(CONFIG_AD7124) += ad7124.o
obj-$(CONFIG_AD7173) += ad7173.o
obj-$(CONFIG_AD7266) += ad7266.o
obj-$(CONFIG_AD7291) += ad7291.o
+obj-$(CONFIG_AD7292) += ad7292.o
obj-$(CONFIG_AD7298) += ad7298.o
obj-$(CONFIG_AD738X) += ad738x.o
obj-$(CONFIG_AD7768) += ad7768-1.o
diff --git a/drivers/iio/adc/ad7292.c b/drivers/iio/adc/ad7292.c
new file mode 100644
index 000000000000..a6798f7dfdb8
--- /dev/null
+++ b/drivers/iio/adc/ad7292.c
@@ -0,0 +1,350 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Analog Devices AD7292 SPI ADC driver
+ *
+ * Copyright 2019 Analog Devices Inc.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#include <linux/iio/iio.h>
+
+#define ADI_VENDOR_ID 0x0018
+
+/* AD7292 registers definition */
+#define AD7292_REG_VENDOR_ID 0x00
+#define AD7292_REG_CONF_BANK 0x05
+#define AD7292_REG_CONV_COMM 0x0E
+#define AD7292_REG_ADC_CH(x) (0x10 + (x))
+
+/* AD7292 configuration bank subregisters definition */
+#define AD7292_BANK_REG_VIN_RNG0 0x10
+#define AD7292_BANK_REG_VIN_RNG1 0x11
+#define AD7292_BANK_REG_SAMP_MODE 0x12
+
+#define AD7292_RD_FLAG_MSK(x) (BIT(7) | ((x) & 0x3F))
+
+/* AD7292_REG_ADC_CONVERSION */
+#define AD7292_ADC_DATA_MASK GENMASK(15, 6)
+#define AD7292_ADC_DATA(x) FIELD_GET(AD7292_ADC_DATA_MASK, x)
+
+/* AD7292_CHANNEL_SAMPLING_MODE */
+#define AD7292_CH_SAMP_MODE(reg, ch) (((reg) >> 8) & BIT(ch))
+
+/* AD7292_CHANNEL_VIN_RANGE */
+#define AD7292_CH_VIN_RANGE(reg, ch) ((reg) & BIT(ch))
+
+#define AD7292_VOLTAGE_CHAN(_chan) \
+{ \
+ .type = IIO_VOLTAGE, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
+ BIT(IIO_CHAN_INFO_SCALE), \
+ .indexed = 1, \
+ .channel = _chan, \
+}
+
+static const struct iio_chan_spec ad7292_channels[] = {
+ AD7292_VOLTAGE_CHAN(0),
+ AD7292_VOLTAGE_CHAN(1),
+ AD7292_VOLTAGE_CHAN(2),
+ AD7292_VOLTAGE_CHAN(3),
+ AD7292_VOLTAGE_CHAN(4),
+ AD7292_VOLTAGE_CHAN(5),
+ AD7292_VOLTAGE_CHAN(6),
+ AD7292_VOLTAGE_CHAN(7)
+};
+
+static const struct iio_chan_spec ad7292_channels_diff[] = {
+ {
+ .type = IIO_VOLTAGE,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+ .indexed = 1,
+ .differential = 1,
+ .channel = 0,
+ .channel2 = 1,
+ },
+ AD7292_VOLTAGE_CHAN(2),
+ AD7292_VOLTAGE_CHAN(3),
+ AD7292_VOLTAGE_CHAN(4),
+ AD7292_VOLTAGE_CHAN(5),
+ AD7292_VOLTAGE_CHAN(6),
+ AD7292_VOLTAGE_CHAN(7)
+};
+
+struct ad7292_state {
+ struct spi_device *spi;
+ struct regulator *reg;
+ unsigned short vref_mv;
+
+ __be16 d16 ____cacheline_aligned;
+ u8 d8[2];
+};
+
+static int ad7292_spi_reg_read(struct ad7292_state *st, unsigned int addr)
+{
+ int ret;
+
+ st->d8[0] = AD7292_RD_FLAG_MSK(addr);
+
+ ret = spi_write_then_read(st->spi, st->d8, 1, &st->d16, 2);
+ if (ret < 0)
+ return ret;
+
+ return be16_to_cpu(st->d16);
+}
+
+static int ad7292_spi_subreg_read(struct ad7292_state *st, unsigned int addr,
+ unsigned int sub_addr, unsigned int len)
+{
+ unsigned int shift = 16 - (8 * len);
+ int ret;
+
+ st->d8[0] = AD7292_RD_FLAG_MSK(addr);
+ st->d8[1] = sub_addr;
+
+ ret = spi_write_then_read(st->spi, st->d8, 2, &st->d16, len);
+ if (ret < 0)
+ return ret;
+
+ return (be16_to_cpu(st->d16) >> shift);
+}
+
+static int ad7292_single_conversion(struct ad7292_state *st,
+ unsigned int chan_addr)
+{
+ int ret;
+
+ struct spi_transfer t[] = {
+ {
+ .tx_buf = &st->d8,
+ .len = 4,
+ .delay_usecs = 6,
+ }, {
+ .rx_buf = &st->d16,
+ .len = 2,
+ },
+ };
+
+ st->d8[0] = chan_addr;
+ st->d8[1] = AD7292_RD_FLAG_MSK(AD7292_REG_CONV_COMM);
+
+ ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t));
+
+ if (ret < 0)
+ return ret;
+
+ return be16_to_cpu(st->d16);
+}
+
+static int ad7292_vin_range_multiplier(struct ad7292_state *st, int channel)
+{
+ int samp_mode, range0, range1, factor = 1;
+
+ /*
+ * Every AD7292 ADC channel may have its input range adjusted according
+ * to the settings at the ADC sampling mode and VIN range subregisters.
+ * For a given channel, the minimum input range is equal to Vref, and it
+ * may be increased by a multiplier factor of 2 or 4 according to the
+ * following rule:
+ * If channel is being sampled with respect to AGND:
+ * factor = 4 if VIN range0 and VIN range1 equal 0
+ * factor = 2 if only one of VIN ranges equal 1
+ * factor = 1 if both VIN range0 and VIN range1 equal 1
+ * If channel is being sampled with respect to AVDD:
+ * factor = 4 if VIN range0 and VIN range1 equal 0
+ * Behavior is undefined if any of VIN range doesn't equal 0
+ */
+
+ samp_mode = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
+ AD7292_BANK_REG_SAMP_MODE, 2);
+
+ if (samp_mode < 0)
+ return samp_mode;
+
+ range0 = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
+ AD7292_BANK_REG_VIN_RNG0, 2);
+
+ if (range0 < 0)
+ return range0;
+
+ range1 = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
+ AD7292_BANK_REG_VIN_RNG1, 2);
+
+ if (range1 < 0)
+ return range1;
+
+ if (AD7292_CH_SAMP_MODE(samp_mode, channel)) {
+ /* Sampling with respect to AGND */
+ if (!AD7292_CH_VIN_RANGE(range0, channel))
+ factor *= 2;
+
+ if (!AD7292_CH_VIN_RANGE(range1, channel))
+ factor *= 2;
+
+ } else {
+ /* Sampling with respect to AVDD */
+ if (AD7292_CH_VIN_RANGE(range0, channel) ||
+ AD7292_CH_VIN_RANGE(range1, channel))
+ return -EPERM;
+
+ factor = 4;
+ }
+
+ return factor;
+}
+
+static int ad7292_read_raw(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan,
+ int *val, int *val2, long info)
+{
+ struct ad7292_state *st = iio_priv(indio_dev);
+ unsigned int ch_addr;
+ int ret;
+
+ switch (info) {
+ case IIO_CHAN_INFO_RAW:
+ ch_addr = AD7292_REG_ADC_CH(chan->channel);
+ ret = ad7292_single_conversion(st, ch_addr);
+ if (ret < 0)
+ return ret;
+
+ *val = AD7292_ADC_DATA(ret);
+
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_SCALE:
+ /*
+ * To convert a raw value to standard units, the IIO defines
+ * this formula: Scaled value = (raw + offset) * scale.
+ * For the scale to be a correct multiplier for (raw + offset),
+ * it must be calculated as the input range divided by the
+ * number of possible distinct input values. Given the ADC data
+ * is 10 bit long, it may assume 2^10 distinct values.
+ * Hence, scale = range / 2^10. The IIO_VAL_FRACTIONAL_LOG2
+ * return type indicates to the IIO API to divide *val by 2 to
+ * the power of *val2 when returning from read_raw.
+ */
+
+ ret = ad7292_vin_range_multiplier(st, chan->channel);
+ if (ret < 0)
+ return ret;
+
+ *val = st->vref_mv * ret;
+ *val2 = 10;
+ return IIO_VAL_FRACTIONAL_LOG2;
+ default:
+ break;
+ }
+ return -EINVAL;
+}
+
+static const struct iio_info ad7292_info = {
+ .read_raw = ad7292_read_raw,
+};
+
+static void ad7292_regulator_disable(void *data)
+{
+ struct ad7292_state *st = data;
+
+ regulator_disable(st->reg);
+}
+
+static int ad7292_probe(struct spi_device *spi)
+{
+ struct ad7292_state *st;
+ struct iio_dev *indio_dev;
+ struct device_node *child;
+ bool diff_channels = 0;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ st = iio_priv(indio_dev);
+ st->spi = spi;
+
+ ret = ad7292_spi_reg_read(st, AD7292_REG_VENDOR_ID);
+ if (ret != ADI_VENDOR_ID) {
+ dev_err(&spi->dev, "Wrong vendor id 0x%x\n", ret);
+ return -EINVAL;
+ }
+
+ spi_set_drvdata(spi, indio_dev);
+
+ st->reg = devm_regulator_get_optional(&spi->dev, "vref");
+ if (!IS_ERR(st->reg)) {
+ ret = regulator_enable(st->reg);
+ if (ret) {
+ dev_err(&spi->dev,
+ "Failed to enable external vref supply\n");
+ return ret;
+ }
+
+ ret = devm_add_action_or_reset(&spi->dev,
+ ad7292_regulator_disable, st);
+ if (ret) {
+ regulator_disable(st->reg);
+ return ret;
+ }
+
+ ret = regulator_get_voltage(st->reg);
+ if (ret < 0)
+ return ret;
+
+ st->vref_mv = ret / 1000;
+ } else {
+ /* Use the internal voltage reference. */
+ st->vref_mv = 1250;
+ }
+
+ indio_dev->dev.parent = &spi->dev;
+ indio_dev->name = spi_get_device_id(spi)->name;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->info = &ad7292_info;
+
+ for_each_available_child_of_node(spi->dev.of_node, child) {
+ diff_channels = of_property_read_bool(child, "diff-channels");
+ if (diff_channels)
+ break;
+ }
+
+ if (diff_channels) {
+ indio_dev->num_channels = ARRAY_SIZE(ad7292_channels_diff);
+ indio_dev->channels = ad7292_channels_diff;
+ } else {
+ indio_dev->num_channels = ARRAY_SIZE(ad7292_channels);
+ indio_dev->channels = ad7292_channels;
+ }
+
+ return devm_iio_device_register(&spi->dev, indio_dev);
+}
+
+static const struct spi_device_id ad7292_id_table[] = {
+ { "ad7292", 0 },
+ {}
+};
+MODULE_DEVICE_TABLE(spi, ad7292_id_table);
+
+static const struct of_device_id ad7292_of_match[] = {
+ { .compatible = "adi,ad7292" },
+ { },
+};
+MODULE_DEVICE_TABLE(of, ad7292_of_match);
+
+static struct spi_driver ad7292_driver = {
+ .driver = {
+ .name = "ad7292",
+ .of_match_table = ad7292_of_match,
+ },
+ .probe = ad7292_probe,
+ .id_table = ad7292_id_table,
+};
+module_spi_driver(ad7292_driver);
+
+MODULE_AUTHOR("Marcelo Schmitt <marcelo.schmitt1@gmail.com>");
+MODULE_DESCRIPTION("Analog Devices AD7292 ADC driver");
+MODULE_LICENSE("GPL v2");
--
2.23.0