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Message-Id: <edc52c93e0d4e08619ba8a98674aeb7d49e6dd1b.1756115378.git.jain.abhinav177@gmail.com>
Date: Tue, 26 Aug 2025 02:55:49 +0530
From: Abhinav Jain <jain.abhinav177@...il.com>
To: linux-iio@...r.kernel.org,
devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: lars@...afoo.de,
Michael.Hennerich@...log.com,
alexandru.ardelean@...log.com,
jlc23@...nel.org,
robh+dt@...nel.org,
krzysztof.kozlowski+dt@...aro.org,
conor+dt@...nel.org,
Marcelo.Schmitt@...log.com,
dumitru.ceclan@...log.com,
Jonathan.Santos@...log.com,
dragos.bogdan@...log.com,
Abhinav Jain <jain.abhinav177@...il.com>
Subject: [PATCH v1 2/2] iio: adc: Add initial support for MAX22531 ADC
Add device support for MAX22530-MAX22531.
Implement scale and read functionality for raw/filtered ADC readings.
Signed-off-by: Abhinav Jain <jain.abhinav177@...il.com>
---
MAINTAINERS | 1 +
drivers/iio/adc/Kconfig | 10 ++
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/max22531.c | 191 +++++++++++++++++++++++++++++++++++++
4 files changed, 203 insertions(+)
create mode 100644 drivers/iio/adc/max22531.c
diff --git a/MAINTAINERS b/MAINTAINERS
index 6f26db9cf742..8a63faf1bde7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14708,6 +14708,7 @@ L: linux-iio@...r.kernel.org
S: Maintained
W: https://ez.analog.com/linux-software-drivers
F: Documentation/devicetree/bindings/iio/adc/adi,max22531.yaml
+F: drivers/iio/adc/max22531.c
MAX31335 RTC DRIVER
M: Antoniu Miclaus <antoniu.miclaus@...log.com>
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index ea3ba1397392..a35c3c945e27 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -933,6 +933,16 @@ config MAX1363
To compile this driver as a module, choose M here: the module will be
called max1363.
+config MAX22531
+ tristate "Analog Devices MAX22531 ADC Driver"
+ depends on SPI
+ help
+ Say yes here to build support for field-side self-powered 12-bit
+ isolated Maxim ADCs. (max22530, max22531, max22532).
+
+ To compile this driver as a module, choose M here: the module will be
+ called max22531.
+
config MAX34408
tristate "Maxim max34408/max344089 ADC driver"
depends on I2C
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 09ae6edb2650..0429d9da571f 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -83,6 +83,7 @@ obj-$(CONFIG_MAX11205) += max11205.o
obj-$(CONFIG_MAX11410) += max11410.o
obj-$(CONFIG_MAX1241) += max1241.o
obj-$(CONFIG_MAX1363) += max1363.o
+obj-$(CONFIG_MAX22531) += max22531.o
obj-$(CONFIG_MAX34408) += max34408.o
obj-$(CONFIG_MAX77541_ADC) += max77541-adc.o
obj-$(CONFIG_MAX9611) += max9611.o
diff --git a/drivers/iio/adc/max22531.c b/drivers/iio/adc/max22531.c
new file mode 100644
index 000000000000..fb035225e426
--- /dev/null
+++ b/drivers/iio/adc/max22531.c
@@ -0,0 +1,191 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MAX22531 SPI ADC Driver
+ *
+ * Copyright (C) 2025 Abhinav Jain
+ *
+ * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/max22530-max22532.pdf
+ */
+
+#include <linux/module.h>
+#include <linux/unaligned.h>
+#include <linux/spi/spi.h>
+#include <linux/iio/iio.h>
+#include <linux/regulator/consumer.h>
+
+#define MAX22531_REG_PROD_ID 0x00
+#define MAX22531_REG_ADC_CHAN(x) ((x) + 1)
+#define MAX22531_REG_FADC_CHAN(x) ((x) + 1)
+
+#define MAX22531_VREF_MV 1800
+#define MAX22531_DEVICE_REV_MSK GENMASK(6, 0)
+#define MAX22531_DEVICE_REV 0x01
+
+#define MAX22531_REG_ADDR_MASK GENMASK(7, 2)
+#define MAX22531_REG_WRITE_MASK BIT(1)
+
+enum max22531_id {
+ max22530,
+ max22531,
+ max22532,
+};
+
+struct max22531_chip_info {
+ const char *name;
+};
+
+static struct max22531_chip_info max22531_chip_info_tbl[] = {
+ [max22530] = {
+ .name = "max22530",
+ },
+ [max22531] = {
+ .name = "max22531",
+ },
+ [max22532] = {
+ .name = "max22532",
+ },
+};
+
+struct max22531 {
+ struct spi_device *spi_dev;
+ const struct max22531_chip_info *chip_info;
+};
+
+#define MAX22531_CHANNEL(ch) \
+ { \
+ .type = IIO_VOLTAGE, \
+ .indexed = 1, \
+ .channel = (ch), \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
+ BIT(IIO_CHAN_INFO_AVERAGE_RAW), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+ }
+
+static const struct iio_chan_spec max22531_channels[] = {
+ MAX22531_CHANNEL(0),
+ MAX22531_CHANNEL(1),
+ MAX22531_CHANNEL(2),
+ MAX22531_CHANNEL(3),
+};
+
+static int max22531_reg_read(struct max22531 *adc, unsigned int reg,
+ unsigned int *readval)
+{
+ u8 cmd;
+
+ cmd = FIELD_PREP(MAX22531_REG_ADDR_MASK, reg);
+ *readval = spi_w8r16be(adc->spi_dev, cmd);
+ if (*readval < 0)
+ return *readval;
+
+ return 0;
+}
+
+static int max22531_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ struct max22531 *adc = iio_priv(indio_dev);
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ ret = max22531_reg_read(adc, MAX22531_REG_ADC_CHAN(chan->channel), val);
+ if (ret)
+ return ret;
+ return IIO_VAL_INT;
+
+ case IIO_CHAN_INFO_AVERAGE_RAW:
+ ret = max22531_reg_read(adc, MAX22531_REG_FADC_CHAN(chan->channel), val);
+ if (ret)
+ return ret;
+ return IIO_VAL_INT;
+
+ case IIO_CHAN_INFO_SCALE:
+ *val = MAX22531_VREF_MV;
+ *val2 = 12;
+
+ return IIO_VAL_FRACTIONAL_LOG2;
+
+ default:
+ return -EINVAL;
+ }
+}
+
+static const struct iio_info max22531_info = {
+ .read_raw = max22531_read_raw,
+};
+
+static int max22531_probe(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev;
+ struct max22531 *adc;
+ unsigned int prod_id;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ adc = iio_priv(indio_dev);
+ adc->spi_dev = spi;
+ adc->chip_info = spi_get_device_match_data(spi);
+ if (!adc->chip_info)
+ return dev_err_probe(&spi->dev, -EINVAL,
+ "no chip info\n");
+
+ indio_dev->name = adc->chip_info->name;
+ indio_dev->info = &max22531_info;
+ indio_dev->channels = max22531_channels;
+ indio_dev->num_channels = ARRAY_SIZE(max22531_channels);
+
+ ret = devm_regulator_get_enable(&spi->dev, "vddl");
+ if (ret)
+ return dev_err_probe(&spi->dev, ret,
+ "Failed to retrieve power logic supply.\n");
+
+ ret = devm_regulator_get_enable(&spi->dev, "vddpl");
+ if (ret)
+ return dev_err_probe(&spi->dev, ret,
+ "Failed to retrieve isolated DC-DC supply.\n");
+
+ ret = max22531_reg_read(adc, MAX22531_REG_PROD_ID, &prod_id);
+ if (ret ||
+ FIELD_GET(MAX22531_DEVICE_REV_MSK, prod_id) != MAX22531_DEVICE_REV)
+ dev_warn(&spi->dev, "PROD_ID verification failed\n");
+
+ return devm_iio_device_register(&spi->dev, indio_dev);
+}
+
+static const struct spi_device_id max22531_id[] = {
+ { "max22530", (kernel_ulong_t)&max22531_chip_info_tbl[max22530] },
+ { "max22531", (kernel_ulong_t)&max22531_chip_info_tbl[max22531] },
+ { "max22532", (kernel_ulong_t)&max22531_chip_info_tbl[max22532] },
+ { }
+};
+MODULE_DEVICE_TABLE(spi, max22531_id);
+
+static const struct of_device_id max22531_spi_of_id[] = {
+ { .compatible = "adi,max22530",
+ .data = &max22531_chip_info_tbl[max22530], },
+ { .compatible = "adi,max22531",
+ .data = &max22531_chip_info_tbl[max22531], },
+ { .compatible = "adi,max22532",
+ .data = &max22531_chip_info_tbl[max22532], },
+ { }
+};
+MODULE_DEVICE_TABLE(of, max22531_spi_of_id);
+
+static struct spi_driver max22531_driver = {
+ .driver = {
+ .name = "max22531",
+ .of_match_table = max22531_spi_of_id,
+ },
+ .probe = max22531_probe,
+ .id_table = max22531_id,
+};
+module_spi_driver(max22531_driver);
+
+MODULE_AUTHOR("Abhinav Jain <jain.abhinav177@...il.com>");
+MODULE_DESCRIPTION("MAX22531 ADC");
+MODULE_LICENSE("GPL");
--
2.34.1
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