[PATCH v1 0/4] iio: adc: Add support for MAX8907 ADC cell

[PATCH v1 0/4] 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.

This patchset has 2 dependencies:

- patch 1 of the series requires this patch
  ("regulator: dt-bindings: maxim,max8907: Convert to DT schema")
  https://lore.kernel.org/lkml/20261027114634.79706-2-clamor95@gmail.com/

- patch 4 of the series requires this patch
  ("leds: Add driver for MAX8907 LED cell")
  https://lore.kernel.org/lkml/20261027115006.86032-1-clamor95@gmail.com/
  Or to be sspecific, part that adds max8907-leds to max8907_cells

Svyatoslav Ryhel (4):
  regulator: dt-bindings: maxim,max8907: Document io-channel-cells
    property
  mfd: max8907: Add ADC client support
  iio: adc: Add support for MAX8907 ADC cell
  mfd: max8907: Add ADC cell

 .../bindings/regulator/maxim,max8907.yaml     |   3 +
 drivers/iio/adc/Kconfig                       |  10 +
 drivers/iio/adc/Makefile                      |   1 +
 drivers/iio/adc/max8907-adc.c                 | 195 ++++++++++++++++++
 drivers/mfd/max8907.c                         |  75 +++++++
 include/linux/mfd/max8907.h                   |  53 +++++
 6 files changed, 337 insertions(+)
 create mode 100644 drivers/iio/adc/max8907-adc.c

-- 
2.53.0

[PATCH v1 1/4] regulator: dt-bindings: maxim,max8907: Document io-channel-cells property

[Svyatoslav Ryhel]

The Maxim MAX8907 has a built-in 8-channel ADC. It does not require any
Device Tree (DT) based configuration and is folded into the main PMIC
node. Document this behavior.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
---
 Documentation/devicetree/bindings/regulator/maxim,max8907.yaml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/regulator/maxim,max8907.yaml b/Documentation/devicetree/bindings/regulator/maxim,max8907.yaml
index ee1a305d1c210..ccdeb9ba21e26 100644
--- a/Documentation/devicetree/bindings/regulator/maxim,max8907.yaml
+++ b/Documentation/devicetree/bindings/regulator/maxim,max8907.yaml
@@ -27,6 +27,9 @@ properties:
 
   system-power-controller: true
 
+  "#io-channel-cells":
+    const: 1
+
   mbatt-supply:
     description:
       The input supply for MBATT, BBAT, SDBY, VRTC.
-- 
2.53.0

[PATCH v1 2/4] mfd: max8907: Add ADC client support

[Svyatoslav Ryhel]

The Maxim MAX8907 has an 8-channel ADC at a fixed location. Add client
support for it along with its regmap and interrupts.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
---
 drivers/mfd/max8907.c       | 74 +++++++++++++++++++++++++++++++++++++
 include/linux/mfd/max8907.h | 53 ++++++++++++++++++++++++++
 2 files changed, 127 insertions(+)

diff --git a/drivers/mfd/max8907.c b/drivers/mfd/max8907.c
index 826d7768fd8d0..86579729111ee 100644
--- a/drivers/mfd/max8907.c
+++ b/drivers/mfd/max8907.c
@@ -113,6 +113,48 @@ static const struct regmap_config max8907_regmap_rtc_config = {
 	.cache_type = REGCACHE_MAPLE,
 };
 
+static bool max8907_adc_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MAX8907_REG_TSC_STA_INT:
+	case MAX8907_REG_AUX1_MSB ... MAX8907_REG_TDIE_LSB:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool max8907_adc_is_precious_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MAX8907_REG_TSC_STA_INT:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool max8907_adc_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MAX8907_REG_TSC_STA_INT:
+	case MAX8907_REG_AUX1_MSB ... MAX8907_REG_TDIE_LSB:
+		return false;
+	default:
+		return true;
+	}
+}
+
+static const struct regmap_config max8907_regmap_adc_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.volatile_reg = max8907_adc_is_volatile_reg,
+	.precious_reg = max8907_adc_is_precious_reg,
+	.writeable_reg = max8907_adc_is_writeable_reg,
+	.max_register = MAX8907_REG_TDIE_MEASURE,
+	.cache_type = REGCACHE_MAPLE,
+};
+
 static const struct regmap_irq max8907_chg_irqs[] = {
 	{ .reg_offset = 0, .mask = 1 << 0, },
 	{ .reg_offset = 0, .mask = 1 << 1, },
@@ -175,6 +217,20 @@ static const struct regmap_irq_chip max8907_rtc_irq_chip = {
 	.num_irqs = ARRAY_SIZE(max8907_rtc_irqs),
 };
 
+static const struct regmap_irq max8907_adc_irqs[] = {
+	{ .reg_offset = 0, .mask = BIT(0), },
+	{ .reg_offset = 0, .mask = BIT(1), },
+};
+
+static const struct regmap_irq_chip max8907_adc_irq_chip = {
+	.name = "max8907 adc",
+	.status_base = MAX8907_REG_TSC_STA_INT,
+	.mask_base = MAX8907_REG_TSC_INT_MASK,
+	.num_regs = 1,
+	.irqs = max8907_adc_irqs,
+	.num_irqs = ARRAY_SIZE(max8907_adc_irqs),
+};
+
 static int max8907_power_off(struct sys_off_data *data)
 {
 	struct max8907 *max8907 = data->cb_data;
@@ -220,6 +276,18 @@ static int max8907_i2c_probe(struct i2c_client *i2c)
 		return dev_err_probe(dev, PTR_ERR(max8907->regmap_rtc),
 				     "RTC regmap init failed\n");
 
+	max8907->i2c_adc = devm_i2c_new_dummy_device(dev, i2c->adapter, MAX8907_ADC_I2C_ADDR);
+	if (IS_ERR(max8907->i2c_adc))
+		return PTR_ERR(max8907->i2c_adc);
+
+	i2c_set_clientdata(max8907->i2c_adc, max8907);
+
+	max8907->regmap_adc = devm_regmap_init_i2c(max8907->i2c_adc,
+						   &max8907_regmap_adc_config);
+	if (IS_ERR(max8907->regmap_adc))
+		return dev_err_probe(dev, PTR_ERR(max8907->regmap_adc),
+				     "ADC regmap init failed\n");
+
 	ret = devm_regmap_add_irq_chip(dev, max8907->regmap_gen, max8907->i2c_gen->irq,
 				       IRQF_ONESHOT | IRQF_SHARED, -1, &max8907_chg_irq_chip,
 				       &max8907->irqc_chg);
@@ -238,6 +306,12 @@ static int max8907_i2c_probe(struct i2c_client *i2c)
 	if (ret)
 		return dev_err_probe(dev, ret, "Failed to add rtc irq chip\n");
 
+	ret = devm_regmap_add_irq_chip(dev, max8907->regmap_adc, max8907->i2c_gen->irq,
+				       IRQF_ONESHOT | IRQF_SHARED, -1, &max8907_adc_irq_chip,
+				       &max8907->irqc_adc);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to add adc irq chip\n");
+
 	ret = devm_mfd_add_devices(dev, -1, max8907_cells, ARRAY_SIZE(max8907_cells),
 				   NULL, 0, NULL);
 	if (ret)
diff --git a/include/linux/mfd/max8907.h b/include/linux/mfd/max8907.h
index 35b2ede54f856..cf304afc782d6 100644
--- a/include/linux/mfd/max8907.h
+++ b/include/linux/mfd/max8907.h
@@ -153,6 +153,51 @@
 #define MAX8907_REG_MPL_CNTL		0x1E
 
 /* ADC and Touch Screen Controller register map */
+#define MAX8907_REG_TSC_STA_INT		0x00
+#define MAX8907_REG_TSC_INT_MASK	0x01
+#define MAX8907_REG_TSC_CNFG1		0x02
+#define MAX8907_REG_TSC_CNFG2		0x03
+#define MAX8907_REG_TSC_CNFG3		0x04
+#define MAX8907_REG_ADC_RES_CNFG1	0x06
+#define MAX8907_REG_ADC_AVG_CNFG1	0x07
+#define MAX8907_REG_ADC_ACQ_CNFG1	0x08
+#define MAX8907_REG_ADC_ACQ_CNFG2	0x09
+#define MAX8907_REG_ADC_SCHED		0x10
+#define MAX8907_REG_X_MSB		0x50
+#define MAX8907_REG_X_LSB		0x51
+#define MAX8907_REG_Y_MSB		0x52
+#define MAX8907_REG_Y_LSB		0x53
+#define MAX8907_REG_Z1_MSB		0x54
+#define MAX8907_REG_Z1_LSB		0x55
+#define MAX8907_REG_Z2_MSB		0x56
+#define MAX8907_REG_Z2_LSB		0x57
+#define MAX8907_REG_AUX1_MSB		0x60
+#define MAX8907_REG_AUX1_LSB		0x61
+#define MAX8907_REG_AUX2_MSB		0x62
+#define MAX8907_REG_AUX2_LSB		0x63
+#define MAX8907_REG_VCHG_MSB		0x64
+#define MAX8907_REG_VCHG_LSB		0x65
+#define MAX8907_REG_VBBATT_MSB		0x66
+#define MAX8907_REG_VBBATT_LSB		0x67
+#define MAX8907_REG_VMBATT_MSB		0x68
+#define MAX8907_REG_VMBATT_LSB		0x69
+#define MAX8907_REG_ISNS_MSB		0x6A
+#define MAX8907_REG_ISNS_LSB		0x6B
+#define MAX8907_REG_THM_MSB		0x6C
+#define MAX8907_REG_THM_LSB		0x6D
+#define MAX8907_REG_TDIE_MSB		0x6E
+#define MAX8907_REG_TDIE_LSB		0x6F
+
+#define MAX8907_REG_AUX1_MEASURE	0xC0
+#define MAX8907_REG_AUX2_MEASURE	0xC8
+#define MAX8907_REG_VCHG_MEASURE	0xD0
+#define MAX8907_REG_VBBATT_MEASURE	0xD8
+#define MAX8907_REG_VMBATT_MEASURE	0xE0
+#define MAX8907_REG_ISNS_MEASURE	0xE8
+#define MAX8907_REG_THM_MEASURE		0xF0
+#define MAX8907_REG_TDIE_MEASURE	0xF8
+
+/* Regulator stride */
 #define MAX8907_CTL			0
 #define MAX8907_SEQCNT			1
 #define MAX8907_VOUT			2
@@ -165,6 +210,8 @@
 #define MAX8907_MASK_OUT5V_ENSRC	0x0E
 #define MAX8907_MASK_OUT5V_EN		0x01
 #define MAX8907_MASK_POWER_OFF		0x40
+#define MAX8907_MASK_RST_CFG_INT_REF_EN	0x01
+#define MAX8907_MASK_NREF_OK		0x10
 
 /* Regulator IDs */
 #define MAX8907_MBATT	0
@@ -225,6 +272,9 @@ enum {
 
 	MAX8907_IRQ_RTC_ALARM1 = 0,
 	MAX8907_IRQ_RTC_ALARM0,
+
+	MAX8907_IRQ_TSC_STICK = 0,
+	MAX8907_IRQ_TSC_NSTICK,
 };
 
 struct regmap_irq_chips_data;
@@ -234,11 +284,14 @@ struct max8907 {
 	struct mutex			irq_lock;
 	struct i2c_client		*i2c_gen;
 	struct i2c_client		*i2c_rtc;
+	struct i2c_client		*i2c_adc;
 	struct regmap			*regmap_gen;
 	struct regmap			*regmap_rtc;
+	struct regmap			*regmap_adc;
 	struct regmap_irq_chip_data	*irqc_chg;
 	struct regmap_irq_chip_data	*irqc_on_off;
 	struct regmap_irq_chip_data	*irqc_rtc;
+	struct regmap_irq_chip_data	*irqc_adc;
 };
 
 #endif
-- 
2.53.0

[PATCH v1 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@gmail.com>
---
 drivers/iio/adc/Kconfig       |  10 ++
 drivers/iio/adc/Makefile      |   1 +
 drivers/iio/adc/max8907-adc.c | 195 ++++++++++++++++++++++++++++++++++
 3 files changed, 206 insertions(+)
 create mode 100644 drivers/iio/adc/max8907-adc.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index a802d8ee4dd9c..25b094575a5d3 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1166,6 +1166,16 @@ 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 9e82c21dbd374..12247d8e0aa29 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..d1acb5bc95c15
--- /dev/null
+++ b/drivers/iio/adc/max8907-adc.c
@@ -0,0 +1,195 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/iio/iio.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mfd/max8907.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+
+/* MAX8907_ADC_RES_CNFG1 */
+#define RES_AUX1			BIT(7)
+#define RES_AUX2			BIT(6)
+#define RES_VCHG			BIT(5)
+#define RES_VBBATT			BIT(4)
+#define RES_VMBATT			BIT(3)
+#define RES_ISNS			BIT(2)
+#define RES_THM				BIT(1)
+#define RES_TDIE			BIT(0)
+
+/* MAX8907_ADC_AVG_CNFG1 */
+#define AVG_AUX1_EN			BIT(7)
+#define AVG_AUX2_EN			BIT(6)
+#define AVG_VCHG_EN			BIT(5)
+#define AVG_VBBATT_EN			BIT(4)
+#define AVG_VMBATT_EN			BIT(3)
+#define AVG_ISNS_EN			BIT(2)
+#define AVG_THM_EN			BIT(1)
+#define AVG_TDIE_EN			BIT(0)
+
+/* MAX8907_ADC_ACQ_CNFG1 */
+#define T_ACQ_AUX1			BIT(7)
+#define T_ACQ_AUX2			BIT(5)
+#define T_ACQ_VCHG			BIT(3)
+#define T_ACQ_VBBATT			BIT(1)
+
+/* MAX8907_ADC_ACQ_CNFG2 */
+#define T_ACQ_VMBATT			BIT(6)
+#define T_ACQ_ISNS			BIT(4)
+#define T_ACQ_THM			BIT(2)
+#define T_ACQ_TDIE			BIT(0)
+
+/* MAX8907_ADC_SCHED */
+#define AUTOSCH_ENABLE			BIT(1)
+#define AUTOSCH_TIME			BIT(0)
+
+#define TO_REG(n)			((n) & 0xff)
+#define TO_MEASURE(n)			(((n) >> 8) & 0xff)
+
+enum {
+	TDIE, THM, ISNS, VMBATT, VBBATT, VCHG, AUX2, AUX1
+};
+
+static const u32 max8907_default_ref[] = {
+	4096, 4096, 4096, 8192, 8192, 8192, 2500, 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);
+	unsigned char data[2] = { 0, 0 };
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = regmap_write(*regmap, TO_MEASURE(chan->address), 0);
+		if (ret)
+			return ret;
+
+		ret = regmap_bulk_read(*regmap, TO_REG(chan->address), data, 2);
+		if (ret)
+			return ret;
+
+		*val = ((data[0] << 8) | data[1]) >> 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;
+
+	/* Enable ADC scheduler with 1 second interval */
+	ret = regmap_update_bits(regmap, MAX8907_REG_ADC_SCHED,
+				 AUTOSCH_ENABLE | AUTOSCH_TIME, AUTOSCH_TIME);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+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;
+
+	iio_device_set_parent(indio_dev, dev->parent);
+
+	/* Enable ADCREF */
+	ret = regmap_set_bits(max8907->regmap_gen, MAX8907_REG_RESET_CNFG,
+			      MAX8907_MASK_RST_CFG_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@gmail.com>");
+MODULE_DESCRIPTION("MAX8907 ADC driver");
+MODULE_LICENSE("GPL");
-- 
2.53.0

[PATCH v1 4/4] mfd: max8907: Add ADC cell

[Svyatoslav Ryhel]

Add the ADC cell name to the list of MAX8907 cells.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
---
 drivers/mfd/max8907.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/mfd/max8907.c b/drivers/mfd/max8907.c
index 86579729111ee..f6b584b002e02 100644
--- a/drivers/mfd/max8907.c
+++ b/drivers/mfd/max8907.c
@@ -20,6 +20,7 @@
 #include <linux/slab.h>
 
 static const struct mfd_cell max8907_cells[] = {
+	{ .name = "max8907-adc", },
 	{ .name = "max8907-leds", },
 	{ .name = "max8907-regulator", },
 	{ .name = "max8907-rtc", },
-- 
2.53.0

Re: [PATCH v1 1/4] regulator: dt-bindings: maxim,max8907: Document io-channel-cells property

[Mark Brown]

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On Sun, Nov 08, 2026 at 11:56:31AM +0200, Svyatoslav Ryhel wrote:
> The Maxim MAX8907 has a built-in 8-channel ADC. It does not require any
> Device Tree (DT) based configuration and is folded into the main PMIC
> node. Document this behavior.

Acked-by: Mark Brown <broonie@kernel.org>

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