iio: adc: ad7405: add ad7405 driver

Add support for the AD7405/ADUM770x, a high performance isolated ADC,
1-channel, 16-bit with a second-order Σ-Δ modulator that converts an
analog input signal into a high speed, single-bit data stream.

Signed-off-by: Pop Ioan Daniel <pop.ioan-daniel@analog.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Link: https://patch.msgid.link/20250605150948.3091827-6-pop.ioan-daniel@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 3bd03df9a9761f20e2b1b71b51ebe43ba7f51b60..799437f918df8bd7d7c4565484644e96a1abe9ae 100644 (file)
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -266,6 +266,16 @@ config AD7380
          To compile this driver as a module, choose M here: the module will be
          called ad7380.
 
+config AD7405
+       tristate "Analog Device AD7405 ADC Driver"
+       depends on IIO_BACKEND
+       help
+         Say yes here to build support for Analog Devices AD7405, ADUM7701,
+         ADUM7702, ADUM7703 analog to digital converters (ADC).
+
+         To compile this driver as a module, choose M here: the module will be
+         called ad7405.
+
 config AD7476
        tristate "Analog Devices AD7476 1-channel ADCs driver and other similar devices from AD and TI"
        depends on SPI

diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 6516ccb4d63bcfe2e2d56c39da7b906fdbe62319..15c60544a475a76d3a30acc95ddf6e659f5129ba 100644 (file)
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -27,6 +27,7 @@ obj-$(CONFIG_AD7291) += ad7291.o
 obj-$(CONFIG_AD7292) += ad7292.o
 obj-$(CONFIG_AD7298) += ad7298.o
 obj-$(CONFIG_AD7380) += ad7380.o
+obj-$(CONFIG_AD7405) += ad7405.o
 obj-$(CONFIG_AD7476) += ad7476.o
 obj-$(CONFIG_AD7606_IFACE_PARALLEL) += ad7606_par.o
 obj-$(CONFIG_AD7606_IFACE_SPI) += ad7606_spi.o

diff --git a/drivers/iio/adc/ad7405.c b/drivers/iio/adc/ad7405.c
new file mode 100644 (file)
index 0000000..9adf85a
--- /dev/null
+++ b/drivers/iio/adc/ad7405.c
@@ -0,0 +1,253 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Analog Devices AD7405 driver
+ *
+ * Copyright 2025 Analog Devices Inc.
+ */
+
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regulator/consumer.h>
+#include <linux/util_macros.h>
+
+#include <linux/iio/backend.h>
+#include <linux/iio/iio.h>
+
+static const unsigned int ad7405_dec_rates_range[] = {
+       32, 1, 4096,
+};
+
+struct ad7405_chip_info {
+       const char *name;
+       const unsigned int full_scale_mv;
+};
+
+struct ad7405_state {
+       struct iio_backend *back;
+       const struct ad7405_chip_info *info;
+       unsigned int ref_frequency;
+       unsigned int dec_rate;
+};
+
+static int ad7405_set_dec_rate(struct iio_dev *indio_dev,
+                              const struct iio_chan_spec *chan,
+                              unsigned int dec_rate)
+{
+       struct ad7405_state *st = iio_priv(indio_dev);
+       int ret;
+
+       if (dec_rate > 4096 || dec_rate < 32)
+               return -EINVAL;
+
+       if (!iio_device_claim_direct(indio_dev))
+               return -EBUSY;
+
+       ret = iio_backend_oversampling_ratio_set(st->back, chan->scan_index, dec_rate);
+       iio_device_release_direct(indio_dev);
+
+       if (ret < 0)
+               return ret;
+
+       st->dec_rate = dec_rate;
+
+       return 0;
+}
+
+static int ad7405_read_raw(struct iio_dev *indio_dev,
+                          const struct iio_chan_spec *chan, int *val,
+                          int *val2, long info)
+{
+       struct ad7405_state *st = iio_priv(indio_dev);
+
+       switch (info) {
+       case IIO_CHAN_INFO_SCALE:
+               *val = st->info->full_scale_mv;
+               *val2 = indio_dev->channels[0].scan_type.realbits - 1;
+               return IIO_VAL_FRACTIONAL_LOG2;
+       case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+               *val = st->dec_rate;
+               return IIO_VAL_INT;
+       case IIO_CHAN_INFO_SAMP_FREQ:
+               *val = DIV_ROUND_CLOSEST_ULL(st->ref_frequency, st->dec_rate);
+               return IIO_VAL_INT;
+       case IIO_CHAN_INFO_OFFSET:
+               *val = -(1 << (indio_dev->channels[0].scan_type.realbits - 1));
+               return IIO_VAL_INT;
+       default:
+               return -EINVAL;
+       }
+}
+
+static int ad7405_write_raw(struct iio_dev *indio_dev,
+                           struct iio_chan_spec const *chan, int val,
+                           int val2, long info)
+{
+       switch (info) {
+       case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+               if (val < 0)
+                       return -EINVAL;
+               return ad7405_set_dec_rate(indio_dev, chan, val);
+       default:
+               return -EINVAL;
+       }
+}
+
+static int ad7405_read_avail(struct iio_dev *indio_dev,
+                            struct iio_chan_spec const *chan,
+                            const int **vals, int *type, int *length,
+                            long info)
+{
+       switch (info) {
+       case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+               *vals = ad7405_dec_rates_range;
+               *type = IIO_VAL_INT;
+               return IIO_AVAIL_RANGE;
+       default:
+               return -EINVAL;
+       }
+}
+
+static const struct iio_info ad7405_iio_info = {
+       .read_raw = &ad7405_read_raw,
+       .write_raw = &ad7405_write_raw,
+       .read_avail = &ad7405_read_avail,
+};
+
+static const struct iio_chan_spec ad7405_channel = {
+       .type = IIO_VOLTAGE,
+       .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
+                       BIT(IIO_CHAN_INFO_OFFSET),
+       .info_mask_shared_by_all = IIO_CHAN_INFO_SAMP_FREQ |
+                       BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+       .info_mask_shared_by_all_available =
+                       BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+       .indexed = 1,
+       .channel = 0,
+       .channel2 = 1,
+       .differential = 1,
+       .scan_index = 0,
+       .scan_type = {
+               .sign = 'u',
+               .realbits = 16,
+               .storagebits = 16,
+       },
+};
+
+static const struct ad7405_chip_info ad7405_chip_info = {
+       .name = "ad7405",
+       .full_scale_mv = 320,
+};
+
+static const struct ad7405_chip_info adum7701_chip_info = {
+       .name = "adum7701",
+       .full_scale_mv = 320,
+};
+
+static const struct ad7405_chip_info adum7702_chip_info = {
+       .name = "adum7702",
+       .full_scale_mv = 64,
+};
+
+static const struct ad7405_chip_info adum7703_chip_info = {
+       .name = "adum7703",
+       .full_scale_mv = 320,
+};
+
+static const char * const ad7405_power_supplies[] = {
+       "vdd1", "vdd2",
+};
+
+static int ad7405_probe(struct platform_device *pdev)
+{
+       struct device *dev = &pdev->dev;
+       struct iio_dev *indio_dev;
+       struct ad7405_state *st;
+       struct clk *clk;
+       int ret;
+
+       indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
+       if (!indio_dev)
+               return -ENOMEM;
+
+       st = iio_priv(indio_dev);
+
+       st->info = device_get_match_data(dev);
+       if (!st->info)
+               return dev_err_probe(dev, -EINVAL, "no chip info\n");
+
+       ret = devm_regulator_bulk_get_enable(dev, ARRAY_SIZE(ad7405_power_supplies),
+                                            ad7405_power_supplies);
+       if (ret)
+               return dev_err_probe(dev, ret, "failed to get and enable supplies");
+
+       clk = devm_clk_get_enabled(dev, NULL);
+       if (IS_ERR(clk))
+               return PTR_ERR(clk);
+
+       st->ref_frequency = clk_get_rate(clk);
+       if (!st->ref_frequency)
+               return -EINVAL;
+
+       indio_dev->name = st->info->name;
+       indio_dev->channels = &ad7405_channel;
+       indio_dev->num_channels = 1;
+       indio_dev->info = &ad7405_iio_info;
+
+       st->back = devm_iio_backend_get(dev, NULL);
+       if (IS_ERR(st->back))
+               return dev_err_probe(dev, PTR_ERR(st->back),
+                                    "failed to get IIO backend");
+
+       ret = iio_backend_chan_enable(st->back, 0);
+       if (ret)
+               return ret;
+
+       ret = devm_iio_backend_request_buffer(dev, st->back, indio_dev);
+       if (ret)
+               return ret;
+
+       ret = devm_iio_backend_enable(dev, st->back);
+       if (ret)
+               return ret;
+
+       /*
+        * Set 256 decimation rate. The default value in the AXI_ADC register
+        * is 0, so we set the register with a decimation rate value that is
+        * functional for all parts.
+        */
+       ret = ad7405_set_dec_rate(indio_dev, &indio_dev->channels[0], 256);
+       if (ret)
+               return ret;
+
+       return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct of_device_id ad7405_of_match[] = {
+       { .compatible = "adi,ad7405", .data = &ad7405_chip_info, },
+       { .compatible = "adi,adum7701", .data = &adum7701_chip_info, },
+       { .compatible = "adi,adum7702", .data = &adum7702_chip_info, },
+       { .compatible = "adi,adum7703", .data = &adum7703_chip_info, },
+       { }
+};
+MODULE_DEVICE_TABLE(of, ad7405_of_match);
+
+static struct platform_driver ad7405_driver = {
+       .driver = {
+               .name = "ad7405",
+               .of_match_table = ad7405_of_match,
+       },
+       .probe = ad7405_probe,
+};
+module_platform_driver(ad7405_driver);
+
+MODULE_AUTHOR("Dragos Bogdan <dragos.bogdan@analog.com>");
+MODULE_AUTHOR("Pop Ioan Daniel <pop.ioan-daniel@analog.com>");
+MODULE_DESCRIPTION("Analog Devices AD7405 driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("IIO_BACKEND");