[PATCH v2 3/4] iio: adc: Add support for MAX8907 ADC cell

[Svyatoslav Ryhel]

The MAX8907 PMIC has a dedicated ADC cell, which provides 8 ADC channels
with information about different parts of the power system, including the
battery, charger/plug, jack and thermal readings.

Signed-off-by: Svyatoslav Ryhel <clamor95@xxxxxxxxx>
---
 drivers/iio/adc/Kconfig       |  10 ++
 drivers/iio/adc/Makefile      |   1 +
 drivers/iio/adc/max8907-adc.c | 169 ++++++++++++++++++++++++++++++++++
 3 files changed, 180 insertions(+)
 create mode 100644 drivers/iio/adc/max8907-adc.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index f8456c8039883..4d5bd8f93fb8c 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1176,6 +1176,16 @@ config MAX77541_ADC
 	  To compile this driver as a module, choose M here:
 	  the module will be called max77541-adc.
 
+config MAX8907_ADC
+	tristate "Maxim MAX8907 ADC driver"
+	depends on MFD_MAX8907
+	help
+	  Say yes here to build support for 8 channel 12-bit ADC
+	  interface found in the Maxim MAX8907 PMIC.
+
+	  To compile this driver as a module, choose M here:
+	  the module will be called max8907-adc.
+
 config MAX9611
 	tristate "Maxim max9611/max9612 ADC driver"
 	depends on I2C
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index d7bb4815df61c..8e6755315aa35 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -99,6 +99,7 @@ obj-$(CONFIG_MAX14001) += max14001.o
 obj-$(CONFIG_MAX34408) += max34408.o
 obj-$(CONFIG_MAX40080) += max40080.o
 obj-$(CONFIG_MAX77541_ADC) += max77541-adc.o
+obj-$(CONFIG_MAX8907_ADC) += max8907-adc.o
 obj-$(CONFIG_MAX9611) += max9611.o
 obj-$(CONFIG_MCP320X) += mcp320x.o
 obj-$(CONFIG_MCP3422) += mcp3422.o
diff --git a/drivers/iio/adc/max8907-adc.c b/drivers/iio/adc/max8907-adc.c
new file mode 100644
index 0000000000000..1776032efc913
--- /dev/null
+++ b/drivers/iio/adc/max8907-adc.c
@@ -0,0 +1,169 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/mfd/max8907.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+
+#define MAX8907_ADC_SCHED_AUTOSCH_ENABLE	BIT(1)
+#define MAX8907_ADC_SCHED_AUTOSCH_TIME		BIT(0)
+
+#define MAX8907_TO_REG(n)			((n) & 0xff)
+#define MAX8907_TO_MEASURE(n)			(((n) >> 8) & 0xff)
+
+enum {
+	TDIE, THM, ISNS, VMBATT, VBBATT, VCHG, AUX2, AUX1
+};
+
+static const u32 max8907_default_ref[] = {
+	[TDIE] = 4096,
+	[THM] = 4096,
+	[ISNS] = 4096,
+	[VMBATT] = 8192,
+	[VBBATT] = 8192,
+	[VCHG] = 8192,
+	[AUX2] = 2500,
+	[AUX1] 4096,
+};
+
+#define MAX8907_CHAN(_type, _idname, _datasheet_name) {		\
+	.type = (_type),					\
+	.address = MAX8907_REG_##_idname##_MSB |		\
+		   MAX8907_REG_##_idname##_MEASURE << 8,	\
+	.indexed = 1,						\
+	.channel = (_idname),					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
+			      BIT(IIO_CHAN_INFO_SCALE),		\
+	.scan_index = (_idname),				\
+	.scan_type = {						\
+		.format = IIO_SCAN_FORMAT_UNSIGNED_INT,		\
+		.realbits = 12,					\
+		.storagebits = 16,				\
+		.endianness = IIO_CPU,				\
+	},							\
+	.datasheet_name = (_datasheet_name),			\
+}
+
+static const struct iio_chan_spec max8907_adc_channels[] = {
+	MAX8907_CHAN(IIO_VOLTAGE, TDIE,   "tdiode"),
+	MAX8907_CHAN(IIO_VOLTAGE, THM,    "thermistor"),
+	MAX8907_CHAN(IIO_CURRENT, ISNS,   "isense"),
+	MAX8907_CHAN(IIO_VOLTAGE, VMBATT, "vmbatt"),
+	MAX8907_CHAN(IIO_VOLTAGE, VBBATT, "vbbatt"),
+	MAX8907_CHAN(IIO_VOLTAGE, VCHG,   "vcharge"),
+	MAX8907_CHAN(IIO_VOLTAGE, AUX2,   "aux2"),
+	MAX8907_CHAN(IIO_VOLTAGE, AUX1,   "aux1"),
+};
+
+static int max8907_adc_read(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct regmap **regmap = iio_priv(indio_dev);
+	__be16 data;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = regmap_write(*regmap, MAX8907_TO_MEASURE(chan->address), 0);
+		if (ret)
+			return ret;
+
+		ret = regmap_bulk_read(*regmap, MAX8907_TO_REG(chan->address), &data, sizeof(data));
+		if (ret)
+			return ret;
+
+		*val = be16_to_cpu(data) >> 4;
+
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+		*val = max8907_default_ref[chan->channel];
+		*val2 = chan->scan_type.realbits;
+
+		return IIO_VAL_FRACTIONAL_LOG2;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info max8907_adc_info = {
+	.read_raw = &max8907_adc_read,
+};
+
+static int max8907_adc_init(struct regmap *regmap)
+{
+	u32 value;
+	int ret;
+
+	/* Enable internal voltage reference. Exact purpose of bits is not known. */
+	ret = regmap_update_bits(regmap, MAX8907_REG_TSC_CNFG1, GENMASK(1, 0), BIT(1));
+	if (ret)
+		return ret;
+
+	/* Check for internal reference IRQ */
+	ret = regmap_read_poll_timeout(regmap, MAX8907_REG_TSC_STA_INT, value,
+				       !(value & MAX8907_MASK_NREF_OK), 0, 1000);
+	if (ret)
+		return ret;
+
+	return regmap_update_bits(regmap, MAX8907_REG_ADC_SCHED,
+				  MAX8907_ADC_SCHED_AUTOSCH_ENABLE |
+				  MAX8907_ADC_SCHED_AUTOSCH_TIME,
+				  MAX8907_ADC_SCHED_AUTOSCH_ENABLE);
+}
+
+static int max8907_adc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct max8907 *max8907 = dev_get_drvdata(dev->parent);
+	struct iio_dev *indio_dev;
+	struct regmap **regmap;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*regmap));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	regmap = iio_priv(indio_dev);
+
+	*regmap = max8907->regmap_adc;
+
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = max8907_adc_channels;
+	indio_dev->num_channels = ARRAY_SIZE(max8907_adc_channels);
+	indio_dev->name = dev_name(dev);
+	indio_dev->info = &max8907_adc_info;
+
+	/*
+	 * The ADC does not require a dedicated node; hence, the PMIC is set as
+	 * the iio_dev parent to enable the use of the PMIC node phandle in the
+	 * Device Tree bindings.
+	 */
+	iio_device_set_parent(indio_dev, dev->parent);
+
+	ret = regmap_set_bits(max8907->regmap_gen, MAX8907_REG_RESET_CNFG,
+			      MAX8907_MASK_INT_REF_EN);
+	if (ret)
+		return ret;
+
+	ret = max8907_adc_init(max8907->regmap_adc);
+	if (ret)
+		return ret;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static struct platform_driver max8907_adc_driver = {
+	.driver.name = "max8907-adc",
+	.probe = max8907_adc_probe,
+};
+module_platform_driver(max8907_adc_driver);
+
+MODULE_ALIAS("platform:max8907-adc");
+MODULE_AUTHOR("Svyatoslav Ryhel <clamor95@xxxxxxxxx>");
+MODULE_DESCRIPTION("MAX8907 ADC driver");
+MODULE_LICENSE("GPL");
-- 
2.53.0