iio: adc: max77541: Add ADI MAX77541 ADC Support

The MAX77541 has an 8-bit Successive Approximation Register (SAR) ADC
with four multiplexers for supporting the telemetry feature.
Signed-off-by: Okan Sahin <okan.sahin@analog.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230412111256.40013-4-okan.sahin@analog.comSigned-off-by: Lee Jones <lee@kernel.org>

drivers/iio/adc/Kconfig

@@ -735,6 +735,17 @@ config MAX1363
 	  To compile this driver as a module, choose M here: the module will be
 	  called max1363.
 
+config MAX77541_ADC
+	tristate "Analog Devices MAX77541 ADC driver"
+	depends on MFD_MAX77541
+	help
+	  This driver controls a Analog Devices MAX77541 ADC
+	  via I2C bus. This device has one adc. Say yes here to build
+	  support for Analog Devices MAX77541 ADC interface.
+
+	  To compile this driver as a module, choose M here:
+	  the module will be called max77541-adc.
+
 config MAX9611
 	tristate "Maxim max9611/max9612 ADC driver"
 	depends on I2C

drivers/iio/adc/Makefile

@@ -67,6 +67,7 @@ obj-$(CONFIG_MAX11205) += max11205.o
 obj-$(CONFIG_MAX11410) += max11410.o
 obj-$(CONFIG_MAX1241) += max1241.o
 obj-$(CONFIG_MAX1363) += max1363.o
+obj-$(CONFIG_MAX77541_ADC) += max77541-adc.o
 obj-$(CONFIG_MAX9611) += max9611.o
 obj-$(CONFIG_MCP320X) += mcp320x.o
 obj-$(CONFIG_MCP3422) += mcp3422.o

drivers/iio/adc/max77541-adc.c

+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2022 Analog Devices, Inc.
+ * ADI MAX77541 ADC Driver with IIO interface
+ */
+
+#include <linux/bitfield.h>
+#include <linux/iio/iio.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/units.h>
+
+#include <linux/mfd/max77541.h>
+
+enum max77541_adc_range {
+	LOW_RANGE,
+	MID_RANGE,
+	HIGH_RANGE,
+};
+
+enum max77541_adc_channel {
+	MAX77541_ADC_VSYS_V,
+	MAX77541_ADC_VOUT1_V,
+	MAX77541_ADC_VOUT2_V,
+	MAX77541_ADC_TEMP,
+};
+
+static int max77541_adc_offset(struct iio_dev *indio_dev,
+			       struct iio_chan_spec const *chan,
+			       int *val, int *val2)
+{
+	switch (chan->channel) {
+	case MAX77541_ADC_TEMP:
+		*val = DIV_ROUND_CLOSEST(ABSOLUTE_ZERO_MILLICELSIUS, 1725);
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int max77541_adc_scale(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan,
+			      int *val, int *val2)
+{
+	struct regmap **regmap = iio_priv(indio_dev);
+	unsigned int reg_val;
+	int ret;
+
+	switch (chan->channel) {
+	case MAX77541_ADC_VSYS_V:
+		*val = 25;
+		return IIO_VAL_INT;
+	case MAX77541_ADC_VOUT1_V:
+	case MAX77541_ADC_VOUT2_V:
+		ret = regmap_read(*regmap, MAX77541_REG_M2_CFG1, &reg_val);
+		if (ret)
+			return ret;
+
+		reg_val = FIELD_GET(MAX77541_BITS_MX_CFG1_RNG, reg_val);
+		switch (reg_val) {
+		case LOW_RANGE:
+			*val = 6;
+			*val2 = 250000;
+			break;
+		case MID_RANGE:
+			*val = 12;
+			*val2 = 500000;
+			break;
+		case HIGH_RANGE:
+			*val = 25;
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+
+		return IIO_VAL_INT_PLUS_MICRO;
+	case MAX77541_ADC_TEMP:
+		*val = 1725;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int max77541_adc_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val)
+{
+	struct regmap **regmap = iio_priv(indio_dev);
+	int ret;
+
+	ret = regmap_read(*regmap, chan->address, val);
+	if (ret)
+		return ret;
+
+	return IIO_VAL_INT;
+}
+
+#define MAX77541_ADC_CHANNEL_V(_channel, _name, _type, _reg) \
+	{							\
+		.type = _type,					\
+		.indexed = 1,					\
+		.channel = _channel,				\
+		.address = _reg,				\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |	\
+				      BIT(IIO_CHAN_INFO_SCALE), \
+		.datasheet_name = _name,			\
+	}
+
+#define MAX77541_ADC_CHANNEL_TEMP(_channel, _name, _type, _reg) \
+	{							\
+		.type = _type,					\
+		.indexed = 1,					\
+		.channel = _channel,				\
+		.address = _reg,				\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |	\
+				      BIT(IIO_CHAN_INFO_SCALE) |\
+				      BIT(IIO_CHAN_INFO_OFFSET),\
+		.datasheet_name = _name,			\
+	}
+
+static const struct iio_chan_spec max77541_adc_channels[] = {
+	MAX77541_ADC_CHANNEL_V(MAX77541_ADC_VSYS_V, "vsys_v", IIO_VOLTAGE,
+			       MAX77541_REG_ADC_DATA_CH1),
+	MAX77541_ADC_CHANNEL_V(MAX77541_ADC_VOUT1_V, "vout1_v", IIO_VOLTAGE,
+			       MAX77541_REG_ADC_DATA_CH2),
+	MAX77541_ADC_CHANNEL_V(MAX77541_ADC_VOUT2_V, "vout2_v", IIO_VOLTAGE,
+			       MAX77541_REG_ADC_DATA_CH3),
+	MAX77541_ADC_CHANNEL_TEMP(MAX77541_ADC_TEMP, "temp", IIO_TEMP,
+				  MAX77541_REG_ADC_DATA_CH6),
+};
+
+static int max77541_adc_read_raw(struct iio_dev *indio_dev,
+				 struct iio_chan_spec const *chan,
+				 int *val, int *val2, long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_OFFSET:
+		return max77541_adc_offset(indio_dev, chan, val, val2);
+	case IIO_CHAN_INFO_SCALE:
+		return max77541_adc_scale(indio_dev, chan, val, val2);
+	case IIO_CHAN_INFO_RAW:
+		return max77541_adc_raw(indio_dev, chan, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info max77541_adc_info = {
+	.read_raw = max77541_adc_read_raw,
+};
+
+static int max77541_adc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct iio_dev *indio_dev;
+	struct regmap **regmap;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*regmap));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	regmap = iio_priv(indio_dev);
+
+	*regmap = dev_get_regmap(dev->parent, NULL);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	indio_dev->name = "max77541";
+	indio_dev->info = &max77541_adc_info;
+	indio_dev->channels = max77541_adc_channels;
+	indio_dev->num_channels = ARRAY_SIZE(max77541_adc_channels);
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct platform_device_id max77541_adc_platform_id[] = {
+	{ "max77541-adc" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(platform, max77541_adc_platform_id);
+
+static struct platform_driver max77541_adc_driver = {
+	.driver = {
+		.name = "max77541-adc",
+	},
+	.probe = max77541_adc_probe,
+	.id_table = max77541_adc_platform_id,
+};
+module_platform_driver(max77541_adc_driver);
+
+MODULE_AUTHOR("Okan Sahin <Okan.Sahin@analog.com>");
+MODULE_DESCRIPTION("MAX77541 ADC driver");
+MODULE_LICENSE("GPL");