[PATCH 0/1] iio: health: add MAX86150 ECG and PPG biosensor driver

[PATCH 0/1] iio: health: add MAX86150 ECG and PPG biosensor driver

[Md Shofiqul Islam]

The MAX86150 (Maxim/Analog Devices) combines two PPG optical channels
(Red/IR LED) and one ECG biopotential channel in a single I2C device.
Data is produced at up to 3200 Hz and buffered in a 32-entry hardware
FIFO with a configurable almost-full interrupt.

This patch adds an IIO driver that exposes three channels:

  in_intensity_red_raw   -- PPG Red LED, 19-bit unsigned
  in_intensity_ir_raw    -- PPG IR LED, 19-bit unsigned
  in_voltage0_raw        -- ECG biopotential, 18-bit signed

Key implementation choices:

  - regmap_noinc_read() for FIFO access: reads 9 bytes (3 slots x 3
    bytes) from the streaming FIFO_DATA register in a single I2C
    burst without address auto-increment.

  - IIO hardware trigger backed by the device interrupt (active-low,
    FIFO almost-full). When an interrupt GPIO is provided in the device
    tree, a trigger is registered and wired to the IIO triggered buffer
    path for continuous low-overhead capture.

  - All resource management uses devm_* APIs.

Known limitations to be addressed in v2:
  - IIO_CHAN_INFO_SCALE not yet implemented.
  - Runtime PM (SYS_CTRL SHDN bit) not yet implemented.
  - Not yet tested on physical hardware.

Md Shofiqul Islam (1):
  iio: health: add MAX86150 ECG and PPG biosensor driver

 .../bindings/iio/health/maxim,max86150.yaml   |  67 +++
 drivers/iio/health/Kconfig                    |  23 +
 drivers/iio/health/Makefile                   |   1 +
 drivers/iio/health/max86150.c                 | 512 ++++++++++++++++++
 4 files changed, 603 insertions(+)
 create mode 100755 Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
 create mode 100755 drivers/iio/health/max86150.c

-- 
2.51.1

[PATCH 1/1] iio: health: add MAX86150 ECG and PPG biosensor driver

[Md Shofiqul Islam]

The MAX86150 (Maxim/Analog Devices) integrates two PPG optical channels
(Red/IR LED) and one ECG biopotential channel in a single I2C device.
Data is captured via a 32-entry hardware FIFO with a configurable
almost-full interrupt.

The driver exposes three IIO channels:
  - in_intensity_red_raw   (PPG Red, 19-bit unsigned)
  - in_intensity_ir_raw    (PPG IR, 19-bit unsigned)
  - in_voltage0_raw        (ECG, 18-bit signed)

A hardware trigger is registered when an interrupt GPIO is provided in
the device tree, enabling the IIO triggered buffer path for continuous
low-overhead capture.

FIFO reads use regmap_noinc_read() to burst-read 9 bytes (3 slots x
3 bytes) from the streaming FIFO_DATA register in a single I2C
transaction.

Signed-off-by: Md Shofiqul Islam <shofiqtest@gmail.com>
---
 .../bindings/iio/health/maxim,max86150.yaml   |  67 +++
 drivers/iio/health/Kconfig                    |  23 +
 drivers/iio/health/Makefile                   |   1 +
 drivers/iio/health/max86150.c                 | 512 ++++++++++++++++++
 4 files changed, 603 insertions(+)
 create mode 100755 Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
 create mode 100755 drivers/iio/health/max86150.c

diff --git a/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml b/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
new file mode 100755
index 000000000000..1bf10fd1a3d2
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
@@ -0,0 +1,67 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/health/maxim,max86150.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Maxim MAX86150 ECG and PPG Biosensor
+
+maintainers:
+  - Md Shofiqul Islam <shofiqtest@gmail.com>
+
+description: |
+  The MAX86150 is an integrated biosensor SoC that combines:
+    - Two PPG (photoplethysmography) channels: Red LED and IR LED,
+      for heart rate and blood-oxygen saturation (SpO2) measurement.
+    - One ECG (electrocardiogram) channel for biopotential recording.
+
+  The device communicates over I2C at up to 400 kHz and raises an
+  active-low interrupt when the 32-entry hardware FIFO reaches its
+  configurable almost-full threshold.
+
+  Datasheet:
+    https://www.analog.com/media/en/technical-documentation/data-sheets/MAX86150.pdf
+
+properties:
+  compatible:
+    const: maxim,max86150
+
+  reg:
+    maxItems: 1
+    description: I2C device address, always 0x5E.
+
+  interrupts:
+    maxItems: 1
+    description: |
+      Active-low interrupt line.  Asserted when the FIFO almost-full
+      threshold is reached or when a new PPG sample is ready.
+
+  vdd-supply:
+    description: Digital core supply, 1.71 V to 1.89 V.
+
+  leds-supply:
+    description: LED anode supply, 3.0 V to 5.5 V.
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        biosensor@5e {
+            compatible = "maxim,max86150";
+            reg = <0x5e>;
+            interrupt-parent = <&gpio1>;
+            interrupts = <5 IRQ_TYPE_EDGE_FALLING>;
+            vdd-supply = <&vdd_1v8>;
+            leds-supply = <&vdd_3v3>;
+        };
+    };
diff --git a/drivers/iio/health/Kconfig b/drivers/iio/health/Kconfig
index a89f3abf11f4..6496cf55290c 100644
--- a/drivers/iio/health/Kconfig
+++ b/drivers/iio/health/Kconfig
@@ -13,6 +13,7 @@ config AFE4403
 	depends on SPI_MASTER
 	select REGMAP_SPI
 	select IIO_BUFFER
+	select IIO_TRIGGER
 	select IIO_TRIGGERED_BUFFER
 	help
 	  Say yes to choose the Texas Instruments AFE4403
@@ -26,6 +27,7 @@ config AFE4404
 	depends on I2C
 	select REGMAP_I2C
 	select IIO_BUFFER
+	select IIO_TRIGGER
 	select IIO_TRIGGERED_BUFFER
 	help
 	  Say yes to choose the Texas Instruments AFE4404
@@ -39,6 +41,7 @@ config MAX30100
 	depends on I2C
 	select REGMAP_I2C
 	select IIO_BUFFER
+	select IIO_TRIGGER
 	select IIO_KFIFO_BUF
 	help
 	  Say Y here to build I2C interface support for the Maxim
@@ -52,6 +55,7 @@ config MAX30102
 	depends on I2C
 	select REGMAP_I2C
 	select IIO_BUFFER
+	select IIO_TRIGGER
 	select IIO_KFIFO_BUF
 	help
 	  Say Y here to build I2C interface support for the Maxim
@@ -62,4 +66,23 @@ config MAX30102
 
 endmenu
 
+
+config MAX86150
+	tristate "MAX86150 ECG and PPG biosensor"
+	depends on I2C
+	select IIO_BUFFER
+	select IIO_TRIGGER
+	select IIO_TRIGGERED_BUFFER
+	select REGMAP_I2C
+	help
+	  Say Y here to enable support for the Maxim MAX86150 combined
+	  ECG and photoplethysmography (PPG) biosensor.
+
+	  The driver exposes three IIO channels: two PPG optical channels
+	  (Red and IR LED) for heart rate and SpO2 monitoring, and one
+	  ECG channel for biopotential recording.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called max86150.
+
 endmenu
diff --git a/drivers/iio/health/Makefile b/drivers/iio/health/Makefile
index 910817112258..04fc73c58444 100644
--- a/drivers/iio/health/Makefile
+++ b/drivers/iio/health/Makefile
@@ -9,3 +9,4 @@ obj-$(CONFIG_AFE4403)		+= afe4403.o
 obj-$(CONFIG_AFE4404)		+= afe4404.o
 obj-$(CONFIG_MAX30100)		+= max30100.o
 obj-$(CONFIG_MAX30102)		+= max30102.o
+obj-$(CONFIG_MAX86150)		+= max86150.o
diff --git a/drivers/iio/health/max86150.c b/drivers/iio/health/max86150.c
new file mode 100755
index 000000000000..3cde4af6650b
--- /dev/null
+++ b/drivers/iio/health/max86150.c
@@ -0,0 +1,512 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MAX86150 combined ECG and PPG biosensor driver
+ *
+ * Copyright (C) 2026 Md Shofiqul Islam <shofiqtest@gmail.com>
+ *
+ * The MAX86150 integrates two PPG optical channels (Red/IR LED) and one
+ * ECG biopotential channel in a single I2C device.  Data is captured
+ * through a 32-entry hardware FIFO with a configurable almost-full
+ * interrupt, making it well-suited for continuous monitoring with a
+ * low-power host.
+ *
+ * Datasheet:
+ *   https://www.analog.com/media/en/technical-documentation/data-sheets/MAX86150.pdf
+ */
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+/* Register addresses */
+#define MAX86150_REG_INT_STATUS1	0x00
+#define MAX86150_REG_INT_STATUS2	0x01
+#define MAX86150_REG_INT_ENABLE1	0x02
+#define MAX86150_REG_INT_ENABLE2	0x03
+#define MAX86150_REG_FIFO_WR_PTR	0x04
+#define MAX86150_REG_OVF_COUNTER	0x05
+#define MAX86150_REG_FIFO_RD_PTR	0x06
+#define MAX86150_REG_FIFO_DATA		0x07
+#define MAX86150_REG_FIFO_CONFIG	0x08
+#define MAX86150_REG_FIFO_DCTRL1	0x09  /* FD1[3:0]  FD2[7:4] */
+#define MAX86150_REG_FIFO_DCTRL2	0x0A  /* FD3[3:0]  FD4[7:4] */
+#define MAX86150_REG_SYS_CTRL		0x0D
+#define MAX86150_REG_PPG_CONFIG1	0x10
+#define MAX86150_REG_PPG_CONFIG2	0x11
+#define MAX86150_REG_LED1_PA		0x14  /* Red LED pulse amplitude */
+#define MAX86150_REG_LED2_PA		0x15  /* IR LED pulse amplitude  */
+#define MAX86150_REG_ECG_CONFIG1	0x3C
+#define MAX86150_REG_ECG_CONFIG3	0x3E
+#define MAX86150_REG_PART_ID		0xFF
+
+/* Field masks */
+#define MAX86150_PART_ID_VAL		0x1E
+
+/* INT_STATUS1 / INT_ENABLE1 */
+#define MAX86150_INT_A_FULL		BIT(7)  /* FIFO almost full */
+#define MAX86150_INT_PPG_RDY		BIT(6)  /* new PPG sample ready */
+
+/* SYS_CTRL */
+#define MAX86150_SYS_SHDN		BIT(1)
+#define MAX86150_SYS_RESET		BIT(0)
+
+/* FIFO_CONFIG */
+#define MAX86150_FIFO_SMP_AVE		GENMASK(7, 5)
+#define MAX86150_FIFO_ROLLOVER_EN	BIT(4)
+#define MAX86150_FIFO_A_FULL		GENMASK(3, 0)
+
+/* FIFO slot data-type codes */
+#define MAX86150_FD_NONE		0x0
+#define MAX86150_FD_LED1		0x1   /* Red PPG */
+#define MAX86150_FD_LED2		0x2   /* IR PPG  */
+#define MAX86150_FD_ECG			0x9
+#define MAX86150_FIFO_FD1		GENMASK(3, 0)
+#define MAX86150_FIFO_FD2		GENMASK(7, 4)
+#define MAX86150_FIFO_FD3		GENMASK(3, 0)
+#define MAX86150_FIFO_FD4		GENMASK(7, 4)
+
+/* PPG_CONFIG1 */
+#define MAX86150_PPG_ADC_RGE		GENMASK(7, 6)
+#define MAX86150_PPG_SR			GENMASK(5, 1)
+
+/* Geometry */
+#define MAX86150_FIFO_DEPTH		32
+#define MAX86150_BYTES_PER_SLOT		3    /* 24-bit word per slot */
+#define MAX86150_NUM_SLOTS		3    /* Red, IR, ECG */
+#define MAX86150_SAMPLE_BYTES		(MAX86150_NUM_SLOTS * MAX86150_BYTES_PER_SLOT)
+
+/* Default hardware configuration */
+#define MAX86150_LED_PA_DEFAULT		0x3F  /* ~50 mA */
+#define MAX86150_PPG_SR_100HZ		4     /* PPG_SR field value for 100 Hz */
+#define MAX86150_PPG_ADC_RGE_16384	2     /* 16384 nA full scale */
+/* Fire A_FULL when 17 slots remain (32 - 15 = 17 samples in FIFO) */
+#define MAX86150_FIFO_A_FULL_VAL	15
+
+/* Scan element indices */
+enum max86150_scan_idx {
+	MAX86150_IDX_PPG_RED = 0,
+	MAX86150_IDX_PPG_IR  = 1,
+	MAX86150_IDX_ECG     = 2,
+	MAX86150_IDX_TS,
+};
+
+/**
+ * struct max86150_data - driver private state
+ * @regmap: register map for this device
+ * @dev:    parent device (for dev_err logging)
+ * @trig:   IIO hardware trigger backed by the device interrupt line
+ * @buf:    DMA-safe capture buffer: 3 x s32 samples + s64 timestamp.
+ *          __aligned(8) satisfies iio_push_to_buffers_with_timestamp().
+ */
+struct max86150_data {
+	struct regmap		*regmap;
+	struct device		*dev;
+	struct iio_trigger	*trig;
+	s32  buf[4] __aligned(8);
+};
+
+/* IIO channel specification */
+
+static const struct iio_chan_spec max86150_channels[] = {
+	{
+		/* PPG Red LED - optical intensity, 19-bit unsigned */
+		.type               = IIO_INTENSITY,
+		.modified           = 1,
+		.channel2           = IIO_MOD_LIGHT_RED,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index         = MAX86150_IDX_PPG_RED,
+		.scan_type = {
+			.sign        = 'u',
+			.realbits    = 19,
+			.storagebits = 32,
+			.endianness  = IIO_LE,
+		},
+	},
+	{
+		/* PPG IR LED - optical intensity, 19-bit unsigned */
+		.type               = IIO_INTENSITY,
+		.modified           = 1,
+		.channel2           = IIO_MOD_LIGHT_IR,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index         = MAX86150_IDX_PPG_IR,
+		.scan_type = {
+			.sign        = 'u',
+			.realbits    = 19,
+			.storagebits = 32,
+			.endianness  = IIO_LE,
+		},
+	},
+	{
+		/* ECG biopotential - voltage, 18-bit signed two's complement */
+		.type               = IIO_VOLTAGE,
+		.channel            = 0,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index         = MAX86150_IDX_ECG,
+		.scan_type = {
+			.sign        = 's',
+			.realbits    = 18,
+			.storagebits = 32,
+			.endianness  = IIO_LE,
+		},
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(MAX86150_IDX_TS),
+};
+
+/* Regmap configuration */
+
+static const struct regmap_config max86150_regmap_config = {
+	.reg_bits     = 8,
+	.val_bits     = 8,
+	.max_register = MAX86150_REG_PART_ID,
+};
+
+/* FIFO helper */
+
+/**
+ * max86150_read_one_sample - burst-read one complete 3-slot FIFO entry
+ * @data:    driver state
+ * @ppg_red: out - 19-bit PPG Red ADC value (unsigned)
+ * @ppg_ir:  out - 19-bit PPG IR ADC value (unsigned)
+ * @ecg:     out - 18-bit ECG ADC value (sign-extended to s32)
+ *
+ * Each FIFO entry is 9 bytes (3 slots x 3 bytes).  FIFO_DATA is a
+ * streaming register - the address does not auto-increment on each
+ * byte, so regmap_noinc_read() is used instead of regmap_bulk_read().
+ *
+ * Byte layout in the 24-bit FIFO word (MSB first):
+ *   PPG 19-bit unsigned: bits [18:0], top 5 bits are always zero
+ *   ECG 18-bit signed:   bits [17:0], top 6 bits are sign extension
+ */
+static int max86150_read_one_sample(struct max86150_data *data,
+				    u32 *ppg_red, u32 *ppg_ir, s32 *ecg)
+{
+	u8 buf[MAX86150_SAMPLE_BYTES];  /* 9 bytes */
+	int ret;
+
+	ret = regmap_noinc_read(data->regmap, MAX86150_REG_FIFO_DATA,
+				buf, sizeof(buf));
+	if (ret)
+		return ret;
+
+	/* Bytes [0..2]: PPG Red - 19-bit value in bits [18:0] */
+	*ppg_red = (u32)(buf[0] & 0x07) << 16 | (u32)buf[1] << 8 | buf[2];
+
+	/* Bytes [3..5]: PPG IR - same format */
+	*ppg_ir  = (u32)(buf[3] & 0x07) << 16 | (u32)buf[4] << 8 | buf[5];
+
+	/* Bytes [6..8]: ECG - 18-bit signed, sign-extend to s32 */
+	*ecg = sign_extend32((u32)(buf[6] & 0x03) << 16 |
+			     (u32)buf[7] << 8 | buf[8], 17);
+
+	return 0;
+}
+
+/* IIO read_raw */
+
+static int max86150_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)
+{
+	struct max86150_data *data = iio_priv(indio_dev);
+	u32 ppg_red, ppg_ir;
+	s32 ecg;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		/*
+		 * Single-shot path: clear the FIFO so we know we are reading
+		 * a sample that arrived after this call, not stale data.
+		 */
+		ret = regmap_write(data->regmap, MAX86150_REG_FIFO_WR_PTR, 0);
+		if (ret)
+			return ret;
+		ret = regmap_write(data->regmap, MAX86150_REG_OVF_COUNTER, 0);
+		if (ret)
+			return ret;
+		ret = regmap_write(data->regmap, MAX86150_REG_FIFO_RD_PTR, 0);
+		if (ret)
+			return ret;
+
+		/* Wait for one complete sample period at 100 Hz (<= 10 ms) */
+		usleep_range(11000, 13000);
+
+		ret = max86150_read_one_sample(data, &ppg_red, &ppg_ir, &ecg);
+		if (ret)
+			return ret;
+
+		switch (chan->scan_index) {
+		case MAX86150_IDX_PPG_RED:
+			*val = ppg_red;
+			break;
+		case MAX86150_IDX_PPG_IR:
+			*val = ppg_ir;
+			break;
+		case MAX86150_IDX_ECG:
+			*val = ecg;
+			break;
+		default:
+			return -EINVAL;
+		}
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+		/*
+		 * TODO: return the hardware scale factor based on the
+		 * configured PPG ADC range (PPG_ADC_RGE) and ECG PGA gain
+		 * (ECG_PGA_GAIN).  For PPG, scale is nA/LSB; for ECG, uV/LSB.
+		 */
+		return -EINVAL;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info max86150_iio_info = {
+	.read_raw = max86150_read_raw,
+};
+
+/* Triggered buffer */
+
+/**
+ * max86150_trigger_handler - threaded IRQ handler for FIFO almost-full
+ *
+ * Called by the IIO buffer infrastructure when the hardware trigger fires.
+ * Reads INT_STATUS1 to de-assert the interrupt, then drains all available
+ * FIFO samples into the IIO push buffer.
+ */
+static irqreturn_t max86150_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func	*pf   = p;
+	struct iio_dev		*idev = pf->indio_dev;
+	struct max86150_data	*data = iio_priv(idev);
+	unsigned int status, wr_ptr, rd_ptr, available;
+	u32 ppg_red, ppg_ir;
+	s32 ecg;
+	int ret;
+
+	/*
+	 * Reading INT_STATUS1 clears the interrupt.  Do this before touching
+	 * the FIFO so the pin is de-asserted while we drain samples.
+	 */
+	ret = regmap_read(data->regmap, MAX86150_REG_INT_STATUS1, &status);
+	if (ret)
+		goto done;
+
+	ret = regmap_read(data->regmap, MAX86150_REG_FIFO_WR_PTR, &wr_ptr);
+	if (ret)
+		goto done;
+	ret = regmap_read(data->regmap, MAX86150_REG_FIFO_RD_PTR, &rd_ptr);
+	if (ret)
+		goto done;
+
+	/*
+	 * Number of unread samples.  The FIFO is circular with depth 32, so
+	 * wrap with (depth - 1) as mask.
+	 */
+	available = (wr_ptr - rd_ptr) & (MAX86150_FIFO_DEPTH - 1);
+
+	while (available--) {
+		ret = max86150_read_one_sample(data, &ppg_red, &ppg_ir, &ecg);
+		if (ret)
+			break;
+
+		data->buf[MAX86150_IDX_PPG_RED] = ppg_red;
+		data->buf[MAX86150_IDX_PPG_IR]  = ppg_ir;
+		data->buf[MAX86150_IDX_ECG]     = ecg;
+
+		iio_push_to_buffers_with_timestamp(idev, data->buf,
+						   iio_get_time_ns(idev));
+	}
+
+done:
+	iio_trigger_notify_done(idev->trig);
+	return IRQ_HANDLED;
+}
+
+/* Chip initialisation */
+
+static int max86150_chip_init(struct max86150_data *data)
+{
+	int ret;
+
+	/* Software reset; the bit self-clears within 1 ms */
+	ret = regmap_write(data->regmap, MAX86150_REG_SYS_CTRL,
+			   MAX86150_SYS_RESET);
+	if (ret)
+		return ret;
+	usleep_range(1000, 2000);
+
+	/*
+	 * FIFO: no sample averaging, rollover enabled, assert A_FULL when
+	 * 17 samples are in the FIFO (32 - 15 = 17 available to read).
+	 */
+	ret = regmap_write(data->regmap, MAX86150_REG_FIFO_CONFIG,
+			   MAX86150_FIFO_ROLLOVER_EN |
+			   FIELD_PREP(MAX86150_FIFO_A_FULL,
+				      MAX86150_FIFO_A_FULL_VAL));
+	if (ret)
+		return ret;
+
+	/* Slot 1 = PPG Red (LED1), Slot 2 = PPG IR (LED2) */
+	ret = regmap_write(data->regmap, MAX86150_REG_FIFO_DCTRL1,
+			   FIELD_PREP(MAX86150_FIFO_FD1, MAX86150_FD_LED1) |
+			   FIELD_PREP(MAX86150_FIFO_FD2, MAX86150_FD_LED2));
+	if (ret)
+		return ret;
+
+	/* Slot 3 = ECG, Slot 4 = disabled */
+	ret = regmap_write(data->regmap, MAX86150_REG_FIFO_DCTRL2,
+			   FIELD_PREP(MAX86150_FIFO_FD3, MAX86150_FD_ECG) |
+			   FIELD_PREP(MAX86150_FIFO_FD4, MAX86150_FD_NONE));
+	if (ret)
+		return ret;
+
+	/* PPG: 100 Hz sample rate, 16384 nA ADC full-scale range */
+	ret = regmap_write(data->regmap, MAX86150_REG_PPG_CONFIG1,
+			   FIELD_PREP(MAX86150_PPG_ADC_RGE,
+				      MAX86150_PPG_ADC_RGE_16384) |
+			   FIELD_PREP(MAX86150_PPG_SR,
+				      MAX86150_PPG_SR_100HZ));
+	if (ret)
+		return ret;
+
+	/* LED pulse amplitudes (~50 mA) */
+	ret = regmap_write(data->regmap, MAX86150_REG_LED1_PA,
+			   MAX86150_LED_PA_DEFAULT);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(data->regmap, MAX86150_REG_LED2_PA,
+			   MAX86150_LED_PA_DEFAULT);
+	if (ret)
+		return ret;
+
+	/* Enable FIFO almost-full interrupt only */
+	return regmap_write(data->regmap, MAX86150_REG_INT_ENABLE1,
+			    MAX86150_INT_A_FULL);
+}
+
+/* Probe */
+
+static int max86150_probe(struct i2c_client *client)
+{
+	struct iio_dev		*indio_dev;
+	struct max86150_data	*data;
+	unsigned int		 part_id;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data     = iio_priv(indio_dev);
+	data->dev = &client->dev;
+
+	data->regmap = devm_regmap_init_i2c(client, &max86150_regmap_config);
+	if (IS_ERR(data->regmap))
+		return dev_err_probe(&client->dev, PTR_ERR(data->regmap),
+				     "Failed to initialise regmap\n");
+
+	ret = regmap_read(data->regmap, MAX86150_REG_PART_ID, &part_id);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Cannot read part ID\n");
+
+	if (part_id != MAX86150_PART_ID_VAL)
+		return dev_err_probe(&client->dev, -ENODEV,
+				     "Unexpected part ID 0x%02x (expected 0x%02x)\n",
+				     part_id, MAX86150_PART_ID_VAL);
+
+	ret = max86150_chip_init(data);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Chip initialisation failed\n");
+
+	indio_dev->name         = "max86150";
+	indio_dev->channels     = max86150_channels;
+	indio_dev->num_channels = ARRAY_SIZE(max86150_channels);
+	indio_dev->info         = &max86150_iio_info;
+	indio_dev->modes        = INDIO_DIRECT_MODE;
+
+	/*
+	 * If the device tree provides an interrupt, set up a hardware
+	 * trigger so userspace can use the FIFO almost-full signal to
+	 * drive capture without polling.
+	 */
+	if (client->irq > 0) {
+		data->trig = devm_iio_trigger_alloc(&client->dev,
+						    "%s-dev%d",
+						    indio_dev->name,
+						    iio_device_id(indio_dev));
+		if (!data->trig)
+			return -ENOMEM;
+
+		ret = devm_request_irq(&client->dev, client->irq,
+				       iio_trigger_generic_data_rdy_poll,
+				       IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+				       "max86150", data->trig);
+		if (ret)
+			return dev_err_probe(&client->dev, ret,
+					     "Cannot request IRQ %d\n",
+					     client->irq);
+
+		iio_trigger_set_drvdata(data->trig, indio_dev);
+
+		ret = devm_iio_trigger_register(&client->dev, data->trig);
+		if (ret)
+			return dev_err_probe(&client->dev, ret,
+					     "Cannot register trigger\n");
+
+		indio_dev->trig = iio_trigger_get(data->trig);
+	}
+
+	ret = devm_iio_triggered_buffer_setup(&client->dev, indio_dev,
+					      iio_pollfunc_store_time,
+					      max86150_trigger_handler,
+					      NULL);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Cannot setup triggered buffer\n");
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+/* I2C driver table */
+
+static const struct i2c_device_id max86150_id[] = {
+	{ "max86150" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max86150_id);
+
+static const struct of_device_id max86150_of_match[] = {
+	{ .compatible = "maxim,max86150" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max86150_of_match);
+
+static struct i2c_driver max86150_driver = {
+	.driver = {
+		.name           = "max86150",
+		.of_match_table = max86150_of_match,
+	},
+	.probe    = max86150_probe,
+	.id_table = max86150_id,
+};
+module_i2c_driver(max86150_driver);
+
+MODULE_AUTHOR("Md Shofiqul Islam <shofiqtest@gmail.com>");
+MODULE_DESCRIPTION("MAX86150 ECG and PPG biosensor driver");
+MODULE_LICENSE("GPL");
-- 
2.51.1

Re: [PATCH 1/1] iio: health: add MAX86150 ECG and PPG biosensor driver

[Joshua Crofts]

On Tue, 23 Jun 2026 17:01:13 +0300
Md Shofiqul Islam <shofiqtest@gmail.com> wrote:

> The MAX86150 (Maxim/Analog Devices) integrates two PPG optical channels
> (Red/IR LED) and one ECG biopotential channel in a single I2C device.
> Data is captured via a 32-entry hardware FIFO with a configurable
> almost-full interrupt.
> 
> The driver exposes three IIO channels:
>   - in_intensity_red_raw   (PPG Red, 19-bit unsigned)
>   - in_intensity_ir_raw    (PPG IR, 19-bit unsigned)
>   - in_voltage0_raw        (ECG, 18-bit signed)
> 
> A hardware trigger is registered when an interrupt GPIO is provided in
> the device tree, enabling the IIO triggered buffer path for continuous
> low-overhead capture.
> 
> FIFO reads use regmap_noinc_read() to burst-read 9 bytes (3 slots x
> 3 bytes) from the streaming FIFO_DATA register in a single I2C
> transaction.
> 
> Signed-off-by: Md Shofiqul Islam <shofiqtest@gmail.com>
> ---
>  .../bindings/iio/health/maxim,max86150.yaml   |  67 +++
>  drivers/iio/health/Kconfig                    |  23 +
>  drivers/iio/health/Makefile                   |   1 +
>  drivers/iio/health/max86150.c                 | 512 ++++++++++++++++++
>  4 files changed, 603 insertions(+)
>  create mode 100755 Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
>  create mode 100755 drivers/iio/health/max86150.c
> 
> diff --git a/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml b/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
> new file mode 100755
> index 000000000000..1bf10fd1a3d2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
> @@ -0,0 +1,67 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/health/maxim,max86150.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +

Split this into 2 patches - one for the new dt-binding and one for the
actual driver, KConfig and Makefile.

Additionally, since you're adding a brand new driver, a MAINTAINERS entry
is required.

Kind regards

CJD

Re: [PATCH 1/1] iio: health: add MAX86150 ECG and PPG biosensor driver

[Krzysztof Kozlowski]

On 23/06/2026 16:01, Md Shofiqul Islam wrote:
> The MAX86150 (Maxim/Analog Devices) integrates two PPG optical channels
> (Red/IR LED) and one ECG biopotential channel in a single I2C device.
> Data is captured via a 32-entry hardware FIFO with a configurable
> almost-full interrupt.
> 
> The driver exposes three IIO channels:
>   - in_intensity_red_raw   (PPG Red, 19-bit unsigned)
>   - in_intensity_ir_raw    (PPG IR, 19-bit unsigned)
>   - in_voltage0_raw        (ECG, 18-bit signed)
> 
> A hardware trigger is registered when an interrupt GPIO is provided in
> the device tree, enabling the IIO triggered buffer path for continuous
> low-overhead capture.
> 
> FIFO reads use regmap_noinc_read() to burst-read 9 bytes (3 slots x
> 3 bytes) from the streaming FIFO_DATA register in a single I2C
> transaction.
> 
> Signed-off-by: Md Shofiqul Islam <shofiqtest@gmail.com>

Please run scripts/checkpatch.pl on the patches and fix reported
warnings. After that, run also 'scripts/checkpatch.pl --strict' on the
patches and (probably) fix more warnings. Some warnings can be ignored,
especially from --strict run, but the code here looks like it needs a
fix. Feel free to get in touch if the warning is not clear.

Best regards,
Krzysztof

[PATCH v2 0/3] iio: health: add MAX86150 ECG and PPG biosensor driver

[Md Shofiqul Islam]

The MAX86150 (Maxim/Analog Devices) combines two PPG optical channels
(Red/IR LED) and one ECG biopotential channel in a single I2C device.
Data is produced at up to 3200 Hz and buffered in a 32-entry hardware
FIFO with a configurable almost-full interrupt.

This series adds:
  1. DT binding YAML schema for maxim,max86150
  2. IIO driver with triggered buffer support
  3. MAINTAINERS entry

Changes in v2 (addressing Sashiko AI review, Joshua Crofts, Krzysztof Kozlowski):
  - Fix buffer overflow: expand scan buffer to s32 buf[6] to hold
    3 x s32 channels + 4-byte pad + s64 timestamp (24 bytes total)
  - Add iio_device_claim_direct() in read_raw to prevent concurrent
    sysfs reads from corrupting FIFO pointers during buffer capture
  - Fix FIFO-full detection: read OVF_COUNTER to distinguish a fully
    saturated FIFO (wr_ptr == rd_ptr after wrap) from an empty one
  - Fix active_scan_mask handling: pack only active channels at
    consecutive positions using test_bit(idx, active_scan_mask)
  - Remove IRQF_ONESHOT from IRQ request (not needed for edge-triggered;
    iio_trigger_generic_data_rdy_poll is a hard-IRQ handler)
  - Add set_trigger_state callback to enable/disable A_FULL interrupt
    only when the IIO buffer is active, preventing the interrupt line
    from asserting before the handler is registered
  - Fix endianness: change scan_type.endianness from IIO_LE to IIO_CPU
    to match native integers written directly into the buffer
  - Add max86150_powerdown() devm action to disable interrupts and
    assert SYS_SHDN on driver unload
  - Add devm_regulator_get_enable() for vdd-supply and leds-supply
    before any I2C access
  - Add devm action for iio_trigger_put() to balance the reference
    count increment from iio_trigger_get()
  - Split DT binding into a separate first patch (requested by Joshua Crofts)
  - Add MAINTAINERS entry (requested by Joshua Crofts)

Known limitations (to be addressed in v3):
  - IIO_CHAN_INFO_SCALE not yet implemented
  - Runtime PM (SYS_CTRL SHDN bit) not yet implemented
  - Not yet tested on physical hardware

Md Shofiqul Islam (3):
  dt-bindings: iio: health: add maxim,max86150
  iio: health: add MAX86150 ECG and PPG biosensor driver
  MAINTAINERS: add entry for MAX86150 IIO health driver

 .../bindings/iio/health/maxim,max86150.yaml   |  67 ++
 MAINTAINERS                                   |   7 +
 drivers/iio/health/Kconfig                    |  18 +
 drivers/iio/health/Makefile                   |   1 +
 drivers/iio/health/max86150.c                 | 612 ++++++++++++++++++
 5 files changed, 705 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
 create mode 100644 drivers/iio/health/max86150.c

-- 
2.51.1

[PATCH v2 1/3] dt-bindings: iio: health: add maxim,max86150

[Md Shofiqul Islam]

Add YAML schema binding for the Maxim MAX86150 combined ECG and PPG
biosensor.  The device communicates over I2C at up to 400 kHz and
exposes an active-low interrupt when the 32-entry hardware FIFO
reaches its configurable almost-full threshold.

Signed-off-by: Md Shofiqul Islam <shofiqtest@gmail.com>
---
 .../bindings/iio/health/maxim,max86150.yaml   | 67 +++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100755 Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml

diff --git a/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml b/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
new file mode 100755
index 000000000000..1bf10fd1a3d2
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
@@ -0,0 +1,67 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/health/maxim,max86150.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Maxim MAX86150 ECG and PPG Biosensor
+
+maintainers:
+  - Md Shofiqul Islam <shofiqtest@gmail.com>
+
+description: |
+  The MAX86150 is an integrated biosensor SoC that combines:
+    - Two PPG (photoplethysmography) channels: Red LED and IR LED,
+      for heart rate and blood-oxygen saturation (SpO2) measurement.
+    - One ECG (electrocardiogram) channel for biopotential recording.
+
+  The device communicates over I2C at up to 400 kHz and raises an
+  active-low interrupt when the 32-entry hardware FIFO reaches its
+  configurable almost-full threshold.
+
+  Datasheet:
+    https://www.analog.com/media/en/technical-documentation/data-sheets/MAX86150.pdf
+
+properties:
+  compatible:
+    const: maxim,max86150
+
+  reg:
+    maxItems: 1
+    description: I2C device address, always 0x5E.
+
+  interrupts:
+    maxItems: 1
+    description: |
+      Active-low interrupt line.  Asserted when the FIFO almost-full
+      threshold is reached or when a new PPG sample is ready.
+
+  vdd-supply:
+    description: Digital core supply, 1.71 V to 1.89 V.
+
+  leds-supply:
+    description: LED anode supply, 3.0 V to 5.5 V.
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        biosensor@5e {
+            compatible = "maxim,max86150";
+            reg = <0x5e>;
+            interrupt-parent = <&gpio1>;
+            interrupts = <5 IRQ_TYPE_EDGE_FALLING>;
+            vdd-supply = <&vdd_1v8>;
+            leds-supply = <&vdd_3v3>;
+        };
+    };
-- 
2.51.1

[PATCH v2 2/3] iio: health: add MAX86150 ECG and PPG biosensor driver

[Md Shofiqul Islam]

The MAX86150 (Maxim/Analog Devices) integrates two PPG optical channels
(Red/IR LED) and one ECG biopotential channel in a single I2C device.
Data is captured via a 32-entry hardware FIFO with a configurable
almost-full interrupt.

The driver exposes three IIO channels:
  - in_intensity_red_raw   (PPG Red, 19-bit unsigned)
  - in_intensity_ir_raw    (PPG IR, 19-bit unsigned)
  - in_voltage0_raw        (ECG, 18-bit signed)

A hardware trigger is registered when an interrupt GPIO is provided in
the device tree, enabling the IIO triggered buffer path for continuous
low-overhead capture.  The trigger enable/disable is driven by the
set_trigger_state callback to prevent the interrupt line from asserting
before the handler is ready.

FIFO reads use regmap_noinc_read() to burst-read 9 bytes (3 slots x
3 bytes) from the streaming FIFO_DATA register in a single I2C
transaction.

Signed-off-by: Md Shofiqul Islam <shofiqtest@gmail.com>
---
 drivers/iio/health/Kconfig    |  23 ++
 drivers/iio/health/Makefile   |   1 +
 drivers/iio/health/max86150.c | 612 ++++++++++++++++++++++++++++++++++
 3 files changed, 636 insertions(+)
 create mode 100755 drivers/iio/health/max86150.c

diff --git a/drivers/iio/health/Kconfig b/drivers/iio/health/Kconfig
index a89f3abf11f4..6496cf55290c 100644
--- a/drivers/iio/health/Kconfig
+++ b/drivers/iio/health/Kconfig
@@ -13,6 +13,7 @@ config AFE4403
 	depends on SPI_MASTER
 	select REGMAP_SPI
 	select IIO_BUFFER
+	select IIO_TRIGGER
 	select IIO_TRIGGERED_BUFFER
 	help
 	  Say yes to choose the Texas Instruments AFE4403
@@ -26,6 +27,7 @@ config AFE4404
 	depends on I2C
 	select REGMAP_I2C
 	select IIO_BUFFER
+	select IIO_TRIGGER
 	select IIO_TRIGGERED_BUFFER
 	help
 	  Say yes to choose the Texas Instruments AFE4404
@@ -39,6 +41,7 @@ config MAX30100
 	depends on I2C
 	select REGMAP_I2C
 	select IIO_BUFFER
+	select IIO_TRIGGER
 	select IIO_KFIFO_BUF
 	help
 	  Say Y here to build I2C interface support for the Maxim
@@ -52,6 +55,7 @@ config MAX30102
 	depends on I2C
 	select REGMAP_I2C
 	select IIO_BUFFER
+	select IIO_TRIGGER
 	select IIO_KFIFO_BUF
 	help
 	  Say Y here to build I2C interface support for the Maxim
@@ -62,4 +66,23 @@ config MAX30102
 
 endmenu
 
+
+config MAX86150
+	tristate "MAX86150 ECG and PPG biosensor"
+	depends on I2C
+	select IIO_BUFFER
+	select IIO_TRIGGER
+	select IIO_TRIGGERED_BUFFER
+	select REGMAP_I2C
+	help
+	  Say Y here to enable support for the Maxim MAX86150 combined
+	  ECG and photoplethysmography (PPG) biosensor.
+
+	  The driver exposes three IIO channels: two PPG optical channels
+	  (Red and IR LED) for heart rate and SpO2 monitoring, and one
+	  ECG channel for biopotential recording.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called max86150.
+
 endmenu
diff --git a/drivers/iio/health/Makefile b/drivers/iio/health/Makefile
index 910817112258..04fc73c58444 100644
--- a/drivers/iio/health/Makefile
+++ b/drivers/iio/health/Makefile
@@ -9,3 +9,4 @@ obj-$(CONFIG_AFE4403)		+= afe4403.o
 obj-$(CONFIG_AFE4404)		+= afe4404.o
 obj-$(CONFIG_MAX30100)		+= max30100.o
 obj-$(CONFIG_MAX30102)		+= max30102.o
+obj-$(CONFIG_MAX86150)		+= max86150.o
diff --git a/drivers/iio/health/max86150.c b/drivers/iio/health/max86150.c
new file mode 100755
index 000000000000..70c51ccb4672
--- /dev/null
+++ b/drivers/iio/health/max86150.c
@@ -0,0 +1,612 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MAX86150 combined ECG and PPG biosensor driver
+ *
+ * Copyright (C) 2026 Md Shofiqul Islam <shofiqtest@gmail.com>
+ *
+ * The MAX86150 integrates two PPG optical channels (Red/IR LED) and one
+ * ECG biopotential channel in a single I2C device.  Data is captured
+ * through a 32-entry hardware FIFO with a configurable almost-full
+ * interrupt, making it well-suited for continuous monitoring with a
+ * low-power host.
+ *
+ * Datasheet:
+ *   https://www.analog.com/media/en/technical-documentation/data-sheets/MAX86150.pdf
+ */
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+
+/* Register addresses */
+#define MAX86150_REG_INT_STATUS1	0x00
+#define MAX86150_REG_INT_STATUS2	0x01
+#define MAX86150_REG_INT_ENABLE1	0x02
+#define MAX86150_REG_INT_ENABLE2	0x03
+#define MAX86150_REG_FIFO_WR_PTR	0x04
+#define MAX86150_REG_OVF_COUNTER	0x05
+#define MAX86150_REG_FIFO_RD_PTR	0x06
+#define MAX86150_REG_FIFO_DATA		0x07
+#define MAX86150_REG_FIFO_CONFIG	0x08
+#define MAX86150_REG_FIFO_DCTRL1	0x09  /* FD1[3:0]  FD2[7:4] */
+#define MAX86150_REG_FIFO_DCTRL2	0x0A  /* FD3[3:0]  FD4[7:4] */
+#define MAX86150_REG_SYS_CTRL		0x0D
+#define MAX86150_REG_PPG_CONFIG1	0x10
+#define MAX86150_REG_PPG_CONFIG2	0x11
+#define MAX86150_REG_LED1_PA		0x14  /* Red LED pulse amplitude */
+#define MAX86150_REG_LED2_PA		0x15  /* IR LED pulse amplitude  */
+#define MAX86150_REG_ECG_CONFIG1	0x3C
+#define MAX86150_REG_ECG_CONFIG3	0x3E
+#define MAX86150_REG_PART_ID		0xFF
+
+/* Field masks */
+#define MAX86150_PART_ID_VAL		0x1E
+
+/* INT_STATUS1 / INT_ENABLE1 */
+#define MAX86150_INT_A_FULL		BIT(7)  /* FIFO almost full */
+#define MAX86150_INT_PPG_RDY		BIT(6)  /* new PPG sample ready */
+
+/* SYS_CTRL */
+#define MAX86150_SYS_SHDN		BIT(1)
+#define MAX86150_SYS_RESET		BIT(0)
+
+/* FIFO_CONFIG */
+#define MAX86150_FIFO_SMP_AVE		GENMASK(7, 5)
+#define MAX86150_FIFO_ROLLOVER_EN	BIT(4)
+#define MAX86150_FIFO_A_FULL		GENMASK(3, 0)
+
+/* FIFO slot data-type codes */
+#define MAX86150_FD_NONE		0x0
+#define MAX86150_FD_LED1		0x1   /* Red PPG */
+#define MAX86150_FD_LED2		0x2   /* IR PPG  */
+#define MAX86150_FD_ECG			0x9
+#define MAX86150_FIFO_FD1		GENMASK(3, 0)
+#define MAX86150_FIFO_FD2		GENMASK(7, 4)
+#define MAX86150_FIFO_FD3		GENMASK(3, 0)
+#define MAX86150_FIFO_FD4		GENMASK(7, 4)
+
+/* PPG_CONFIG1 */
+#define MAX86150_PPG_ADC_RGE		GENMASK(7, 6)
+#define MAX86150_PPG_SR			GENMASK(5, 1)
+
+/* Geometry */
+#define MAX86150_FIFO_DEPTH		32
+#define MAX86150_BYTES_PER_SLOT		3    /* 24-bit word per slot */
+#define MAX86150_NUM_SLOTS		3    /* Red, IR, ECG */
+#define MAX86150_SAMPLE_BYTES		(MAX86150_NUM_SLOTS * MAX86150_BYTES_PER_SLOT)
+
+/* Default hardware configuration */
+#define MAX86150_LED_PA_DEFAULT		0x3F  /* ~50 mA */
+#define MAX86150_PPG_SR_100HZ		4     /* PPG_SR field value for 100 Hz */
+#define MAX86150_PPG_ADC_RGE_16384	2     /* 16384 nA full scale */
+/* Fire A_FULL when 17 slots remain (32 - 15 = 17 samples in FIFO) */
+#define MAX86150_FIFO_A_FULL_VAL	15
+
+/* Scan element indices */
+enum max86150_scan_idx {
+	MAX86150_IDX_PPG_RED = 0,
+	MAX86150_IDX_PPG_IR  = 1,
+	MAX86150_IDX_ECG     = 2,
+	MAX86150_IDX_TS,
+};
+
+/**
+ * struct max86150_data - driver private state
+ * @regmap: register map for this device
+ * @dev:    parent device (for dev_err logging)
+ * @trig:   IIO hardware trigger backed by the device interrupt line
+ * @buf:    DMA-safe capture buffer sized for worst-case (all 3 channels
+ *          active): 3 x s32 (12 bytes) + 4-byte pad + s64 timestamp = 24
+ *          bytes.  __aligned(8) satisfies iio_push_to_buffers_with_timestamp().
+ */
+struct max86150_data {
+	struct regmap		*regmap;
+	struct device		*dev;
+	struct iio_trigger	*trig;
+	s32 buf[6] __aligned(8);
+};
+
+/* IIO channel specification */
+
+static const struct iio_chan_spec max86150_channels[] = {
+	{
+		/* PPG Red LED - optical intensity, 19-bit unsigned */
+		.type               = IIO_INTENSITY,
+		.modified           = 1,
+		.channel2           = IIO_MOD_LIGHT_RED,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index         = MAX86150_IDX_PPG_RED,
+		.scan_type = {
+			.sign        = 'u',
+			.realbits    = 19,
+			.storagebits = 32,
+			.endianness  = IIO_CPU,
+		},
+	},
+	{
+		/* PPG IR LED - optical intensity, 19-bit unsigned */
+		.type               = IIO_INTENSITY,
+		.modified           = 1,
+		.channel2           = IIO_MOD_LIGHT_IR,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index         = MAX86150_IDX_PPG_IR,
+		.scan_type = {
+			.sign        = 'u',
+			.realbits    = 19,
+			.storagebits = 32,
+			.endianness  = IIO_CPU,
+		},
+	},
+	{
+		/* ECG biopotential - voltage, 18-bit signed two's complement */
+		.type               = IIO_VOLTAGE,
+		.channel            = 0,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index         = MAX86150_IDX_ECG,
+		.scan_type = {
+			.sign        = 's',
+			.realbits    = 18,
+			.storagebits = 32,
+			.endianness  = IIO_CPU,
+		},
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(MAX86150_IDX_TS),
+};
+
+/* Regmap configuration */
+
+static const struct regmap_config max86150_regmap_config = {
+	.reg_bits     = 8,
+	.val_bits     = 8,
+	.max_register = MAX86150_REG_PART_ID,
+};
+
+/* FIFO helper */
+
+/**
+ * max86150_read_one_sample - burst-read one complete 3-slot FIFO entry
+ * @data:    driver state
+ * @ppg_red: out - 19-bit PPG Red ADC value (unsigned)
+ * @ppg_ir:  out - 19-bit PPG IR ADC value (unsigned)
+ * @ecg:     out - 18-bit ECG ADC value (sign-extended to s32)
+ *
+ * Each FIFO entry is 9 bytes (3 slots x 3 bytes).  FIFO_DATA is a
+ * streaming register - the address does not auto-increment on each
+ * byte, so regmap_noinc_read() is used instead of regmap_bulk_read().
+ *
+ * Byte layout in the 24-bit FIFO word (MSB first):
+ *   PPG 19-bit unsigned: bits [18:0], top 5 bits are always zero
+ *   ECG 18-bit signed:   bits [17:0], top 6 bits are sign extension
+ */
+static int max86150_read_one_sample(struct max86150_data *data,
+				    u32 *ppg_red, u32 *ppg_ir, s32 *ecg)
+{
+	u8 buf[MAX86150_SAMPLE_BYTES];  /* 9 bytes */
+	int ret;
+
+	ret = regmap_noinc_read(data->regmap, MAX86150_REG_FIFO_DATA,
+				buf, sizeof(buf));
+	if (ret)
+		return ret;
+
+	/* Bytes [0..2]: PPG Red - 19-bit value in bits [18:0] */
+	*ppg_red = (u32)(buf[0] & 0x07) << 16 | (u32)buf[1] << 8 | buf[2];
+
+	/* Bytes [3..5]: PPG IR - same format */
+	*ppg_ir  = (u32)(buf[3] & 0x07) << 16 | (u32)buf[4] << 8 | buf[5];
+
+	/* Bytes [6..8]: ECG - 18-bit signed, sign-extend to s32 */
+	*ecg = sign_extend32((u32)(buf[6] & 0x03) << 16 |
+			     (u32)buf[7] << 8 | buf[8], 17);
+
+	return 0;
+}
+
+/* IIO read_raw */
+
+static int max86150_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)
+{
+	struct max86150_data *data = iio_priv(indio_dev);
+	u32 ppg_red, ppg_ir;
+	s32 ecg;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		/*
+		 * Claim direct mode to prevent concurrent sysfs reads from
+		 * corrupting the FIFO pointers while a triggered buffer
+		 * capture is active.
+		 */
+		if (!iio_device_claim_direct(indio_dev))
+			return -EBUSY;
+
+		/*
+		 * Single-shot path: reset FIFO pointers so the next sample
+		 * read is one that arrived after this call.
+		 */
+		ret = regmap_write(data->regmap, MAX86150_REG_FIFO_WR_PTR, 0);
+		if (!ret)
+			ret = regmap_write(data->regmap,
+					   MAX86150_REG_OVF_COUNTER, 0);
+		if (!ret)
+			ret = regmap_write(data->regmap,
+					   MAX86150_REG_FIFO_RD_PTR, 0);
+		if (ret) {
+			iio_device_release_direct(indio_dev);
+			return ret;
+		}
+
+		/* Wait for one complete sample period at 100 Hz (<= 10 ms) */
+		usleep_range(11000, 13000);
+
+		ret = max86150_read_one_sample(data, &ppg_red, &ppg_ir, &ecg);
+		iio_device_release_direct(indio_dev);
+		if (ret)
+			return ret;
+
+		switch (chan->scan_index) {
+		case MAX86150_IDX_PPG_RED:
+			*val = ppg_red;
+			break;
+		case MAX86150_IDX_PPG_IR:
+			*val = ppg_ir;
+			break;
+		case MAX86150_IDX_ECG:
+			*val = ecg;
+			break;
+		default:
+			return -EINVAL;
+		}
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+		/*
+		 * TODO: return the hardware scale factor based on the
+		 * configured PPG ADC range (PPG_ADC_RGE) and ECG PGA gain
+		 * (ECG_PGA_GAIN).  For PPG, scale is nA/LSB; for ECG, uV/LSB.
+		 */
+		return -EINVAL;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info max86150_iio_info = {
+	.read_raw = max86150_read_raw,
+};
+
+/* Trigger */
+
+/*
+ * Enable or disable the FIFO almost-full interrupt when the IIO triggered
+ * buffer is started or stopped.  Keeping the interrupt masked until capture
+ * is active prevents a pre-existing FIFO fill from asserting the line before
+ * the handler is ready to clear it.
+ */
+static int max86150_set_trigger_state(struct iio_trigger *trig, bool state)
+{
+	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
+	struct max86150_data *data = iio_priv(indio_dev);
+	unsigned int mask = state ? MAX86150_INT_A_FULL : 0;
+
+	return regmap_write(data->regmap, MAX86150_REG_INT_ENABLE1, mask);
+}
+
+static const struct iio_trigger_ops max86150_trigger_ops = {
+	.set_trigger_state = max86150_set_trigger_state,
+};
+
+/* Triggered buffer */
+
+/**
+ * max86150_trigger_handler - threaded IRQ handler for FIFO almost-full
+ *
+ * Called by the IIO buffer infrastructure when the hardware trigger fires.
+ * Reads INT_STATUS1 to de-assert the interrupt, then drains all available
+ * FIFO samples into the IIO push buffer, packing only the channels that
+ * are currently enabled in active_scan_mask.
+ */
+static irqreturn_t max86150_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func	*pf   = p;
+	struct iio_dev		*idev = pf->indio_dev;
+	struct max86150_data	*data = iio_priv(idev);
+	unsigned int status, wr_ptr, rd_ptr, ovf, available;
+	u32 ppg_red, ppg_ir;
+	s32 ecg;
+	int ret, j;
+
+	/*
+	 * Reading INT_STATUS1 clears the interrupt.  Do this before touching
+	 * the FIFO so the pin is de-asserted while we drain samples.
+	 */
+	ret = regmap_read(data->regmap, MAX86150_REG_INT_STATUS1, &status);
+	if (ret)
+		goto done;
+
+	ret = regmap_read(data->regmap, MAX86150_REG_FIFO_WR_PTR, &wr_ptr);
+	if (ret)
+		goto done;
+	ret = regmap_read(data->regmap, MAX86150_REG_FIFO_RD_PTR, &rd_ptr);
+	if (ret)
+		goto done;
+
+	/*
+	 * Read OVF_COUNTER to distinguish a full FIFO from an empty one:
+	 * both produce wr_ptr == rd_ptr after the pointers wrap around.
+	 * If OVF_COUNTER is non-zero the FIFO has saturated; treat all 32
+	 * slots as available so we drain the entire FIFO and clear the
+	 * interrupt condition.
+	 */
+	ret = regmap_read(data->regmap, MAX86150_REG_OVF_COUNTER, &ovf);
+	if (ret)
+		goto done;
+
+	if (ovf > 0)
+		available = MAX86150_FIFO_DEPTH;
+	else
+		available = (wr_ptr - rd_ptr) & (MAX86150_FIFO_DEPTH - 1);
+
+	while (available--) {
+		ret = max86150_read_one_sample(data, &ppg_red, &ppg_ir, &ecg);
+		if (ret)
+			break;
+
+		/*
+		 * Pack only active channels at consecutive positions [0..j-1].
+		 * iio_push_to_buffers_with_timestamp() uses scan_bytes (which
+		 * accounts for the active channel count) to place the timestamp,
+		 * so static indexing would misplace it when fewer than 3
+		 * channels are enabled.
+		 */
+		j = 0;
+		if (test_bit(MAX86150_IDX_PPG_RED, idev->active_scan_mask))
+			data->buf[j++] = ppg_red;
+		if (test_bit(MAX86150_IDX_PPG_IR, idev->active_scan_mask))
+			data->buf[j++] = ppg_ir;
+		if (test_bit(MAX86150_IDX_ECG, idev->active_scan_mask))
+			data->buf[j++] = ecg;
+
+		iio_push_to_buffers_with_timestamp(idev, data->buf,
+						   iio_get_time_ns(idev));
+	}
+
+done:
+	iio_trigger_notify_done(idev->trig);
+	return IRQ_HANDLED;
+}
+
+/* Chip initialisation / teardown */
+
+static void max86150_powerdown(void *arg)
+{
+	struct max86150_data *data = arg;
+
+	regmap_write(data->regmap, MAX86150_REG_INT_ENABLE1, 0);
+	regmap_write(data->regmap, MAX86150_REG_SYS_CTRL, MAX86150_SYS_SHDN);
+}
+
+static int max86150_chip_init(struct max86150_data *data)
+{
+	int ret;
+
+	/* Software reset; the bit self-clears within 1 ms */
+	ret = regmap_write(data->regmap, MAX86150_REG_SYS_CTRL,
+			   MAX86150_SYS_RESET);
+	if (ret)
+		return ret;
+	usleep_range(1000, 2000);
+
+	/*
+	 * FIFO: no sample averaging, rollover enabled, assert A_FULL when
+	 * 17 samples are in the FIFO (32 - 15 = 17 available to read).
+	 */
+	ret = regmap_write(data->regmap, MAX86150_REG_FIFO_CONFIG,
+			   MAX86150_FIFO_ROLLOVER_EN |
+			   FIELD_PREP(MAX86150_FIFO_A_FULL,
+				      MAX86150_FIFO_A_FULL_VAL));
+	if (ret)
+		return ret;
+
+	/* Slot 1 = PPG Red (LED1), Slot 2 = PPG IR (LED2) */
+	ret = regmap_write(data->regmap, MAX86150_REG_FIFO_DCTRL1,
+			   FIELD_PREP(MAX86150_FIFO_FD1, MAX86150_FD_LED1) |
+			   FIELD_PREP(MAX86150_FIFO_FD2, MAX86150_FD_LED2));
+	if (ret)
+		return ret;
+
+	/* Slot 3 = ECG, Slot 4 = disabled */
+	ret = regmap_write(data->regmap, MAX86150_REG_FIFO_DCTRL2,
+			   FIELD_PREP(MAX86150_FIFO_FD3, MAX86150_FD_ECG) |
+			   FIELD_PREP(MAX86150_FIFO_FD4, MAX86150_FD_NONE));
+	if (ret)
+		return ret;
+
+	/* PPG: 100 Hz sample rate, 16384 nA ADC full-scale range */
+	ret = regmap_write(data->regmap, MAX86150_REG_PPG_CONFIG1,
+			   FIELD_PREP(MAX86150_PPG_ADC_RGE,
+				      MAX86150_PPG_ADC_RGE_16384) |
+			   FIELD_PREP(MAX86150_PPG_SR,
+				      MAX86150_PPG_SR_100HZ));
+	if (ret)
+		return ret;
+
+	/* LED pulse amplitudes (~50 mA) */
+	ret = regmap_write(data->regmap, MAX86150_REG_LED1_PA,
+			   MAX86150_LED_PA_DEFAULT);
+	if (ret)
+		return ret;
+
+	return regmap_write(data->regmap, MAX86150_REG_LED2_PA,
+			    MAX86150_LED_PA_DEFAULT);
+	/*
+	 * Do NOT enable the A_FULL interrupt here.  It is enabled and
+	 * disabled via max86150_set_trigger_state() when the IIO triggered
+	 * buffer is started and stopped, which prevents the edge-triggered
+	 * interrupt line from asserting before the handler is registered.
+	 */
+}
+
+static void max86150_trigger_put(void *trig)
+{
+	iio_trigger_put(trig);
+}
+
+/* Probe */
+
+static int max86150_probe(struct i2c_client *client)
+{
+	struct iio_dev		*indio_dev;
+	struct max86150_data	*data;
+	unsigned int		 part_id;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data      = iio_priv(indio_dev);
+	data->dev = &client->dev;
+
+	/*
+	 * Enable power supplies before any I2C access.  Both are optional
+	 * in the device tree (devm_regulator_get_enable returns 0 when the
+	 * supply is not described), but must be present and stable on real
+	 * hardware before the first register read.
+	 */
+	ret = devm_regulator_get_enable(&client->dev, "vdd");
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Failed to get/enable vdd supply\n");
+
+	ret = devm_regulator_get_enable(&client->dev, "leds");
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Failed to get/enable leds supply\n");
+
+	data->regmap = devm_regmap_init_i2c(client, &max86150_regmap_config);
+	if (IS_ERR(data->regmap))
+		return dev_err_probe(&client->dev, PTR_ERR(data->regmap),
+				     "Failed to initialise regmap\n");
+
+	ret = regmap_read(data->regmap, MAX86150_REG_PART_ID, &part_id);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Cannot read part ID\n");
+
+	if (part_id != MAX86150_PART_ID_VAL)
+		return dev_err_probe(&client->dev, -ENODEV,
+				     "Unexpected part ID 0x%02x (expected 0x%02x)\n",
+				     part_id, MAX86150_PART_ID_VAL);
+
+	ret = max86150_chip_init(data);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Chip initialisation failed\n");
+
+	ret = devm_add_action_or_reset(&client->dev, max86150_powerdown, data);
+	if (ret)
+		return ret;
+
+	indio_dev->name         = "max86150";
+	indio_dev->channels     = max86150_channels;
+	indio_dev->num_channels = ARRAY_SIZE(max86150_channels);
+	indio_dev->info         = &max86150_iio_info;
+	indio_dev->modes        = INDIO_DIRECT_MODE;
+
+	/*
+	 * If the device tree provides an interrupt, set up a hardware
+	 * trigger so userspace can use the FIFO almost-full signal to
+	 * drive capture without polling.
+	 */
+	if (client->irq > 0) {
+		data->trig = devm_iio_trigger_alloc(&client->dev,
+						    "%s-dev%d",
+						    indio_dev->name,
+						    iio_device_id(indio_dev));
+		if (!data->trig)
+			return -ENOMEM;
+
+		data->trig->ops = &max86150_trigger_ops;
+		iio_trigger_set_drvdata(data->trig, indio_dev);
+
+		/*
+		 * iio_trigger_generic_data_rdy_poll is a hard-IRQ handler
+		 * that calls iio_trigger_poll() and returns IRQ_HANDLED.
+		 * No IRQF_ONESHOT is needed for this edge-triggered line.
+		 */
+		ret = devm_request_irq(&client->dev, client->irq,
+				       iio_trigger_generic_data_rdy_poll,
+				       IRQF_TRIGGER_FALLING,
+				       "max86150", data->trig);
+		if (ret)
+			return dev_err_probe(&client->dev, ret,
+					     "Cannot request IRQ %d\n",
+					     client->irq);
+
+		ret = devm_iio_trigger_register(&client->dev, data->trig);
+		if (ret)
+			return dev_err_probe(&client->dev, ret,
+					     "Cannot register trigger\n");
+
+		indio_dev->trig = iio_trigger_get(data->trig);
+		ret = devm_add_action_or_reset(&client->dev,
+					       max86150_trigger_put,
+					       data->trig);
+		if (ret)
+			return ret;
+	}
+
+	ret = devm_iio_triggered_buffer_setup(&client->dev, indio_dev,
+					      iio_pollfunc_store_time,
+					      max86150_trigger_handler,
+					      NULL);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Cannot setup triggered buffer\n");
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+/* I2C driver table */
+
+static const struct i2c_device_id max86150_id[] = {
+	{ "max86150" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max86150_id);
+
+static const struct of_device_id max86150_of_match[] = {
+	{ .compatible = "maxim,max86150" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max86150_of_match);
+
+static struct i2c_driver max86150_driver = {
+	.driver = {
+		.name           = "max86150",
+		.of_match_table = max86150_of_match,
+	},
+	.probe    = max86150_probe,
+	.id_table = max86150_id,
+};
+module_i2c_driver(max86150_driver);
+
+MODULE_AUTHOR("Md Shofiqul Islam <shofiqtest@gmail.com>");
+MODULE_DESCRIPTION("MAX86150 ECG and PPG biosensor driver");
+MODULE_LICENSE("GPL");
-- 
2.51.1

[PATCH v2 3/3] MAINTAINERS: add entry for MAX86150 IIO health driver

[Md Shofiqul Islam]

Add maintainer entry for the new MAX86150 ECG and PPG biosensor driver.

Signed-off-by: Md Shofiqul Islam <shofiqtest@gmail.com>
---
 MAINTAINERS | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 3115538ce829..a441ec44bb27 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15863,6 +15863,13 @@ S:	Supported
 F:	Documentation/devicetree/bindings/power/supply/maxim,max77976.yaml
 F:	drivers/power/supply/max77976_charger.c
 
+MAXIM MAX86150 ECG AND PPG BIOSENSOR DRIVER
+M:	Md Shofiqul Islam <shofiqtest@gmail.com>
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
+F:	drivers/iio/health/max86150.c
+
 MAXIM MUIC CHARGER DRIVERS FOR EXYNOS BASED BOARDS
 M:	Krzysztof Kozlowski <krzk@kernel.org>
 L:	linux-pm@vger.kernel.org
-- 
2.51.1

[PATCH v3 0/3] iio: health: add MAX86150 ECG and PPG biosensor driver

[Md Shofiqul Islam]

The MAX86150 (Maxim/Analog Devices) combines two PPG optical channels
(Red/IR LED) and one ECG biopotential channel in a single I2C device.

Changes since v2 (addressing Sashiko review):
 - Move FIFO read buffer from stack to struct field (DMA-safe for I2C host
   controllers that use DMA for burst reads)
 - Remove redundant devm iio_trigger_put action; the IIO core calls
   iio_trigger_put(indio_dev->trig) in iio_dev_release()
 - Remove IIO_CHAN_INFO_SCALE from info_mask_separate until hardware scale
   factors (PPG nA/LSB and ECG uV/LSB) are implemented with register
   readback in a follow-up
 - Reconstruct per-sample timestamps from IRQ capture time (pf->timestamp)
   and the configured sample period (10 ms at 100 Hz) so buffered samples
   carry accurate, evenly-spaced timestamps instead of all sharing the
   drain-loop clock reading
 - Switch to devm_regulator_get_enable_optional() for vdd-supply and
   leds-supply so probing succeeds on boards with fixed (non-DT) rails
 - Zero data->buf at the start of each FIFO drain iteration to prevent
   padding bytes from leaking previous sample data when fewer than 3
   channels are active
 - Flush FIFO (reset wr_ptr, rd_ptr, ovf_counter) in set_trigger_state()
   before enabling the interrupt so capture starts with a clean FIFO
 - Fix file permissions: both new files are 100644

Changes since v1 (addressing Joshua Crofts and Krzysztof Kozlowski review):
 - Split into 3 patches: DT binding / driver+Kconfig+Makefile / MAINTAINERS
 - Add MAINTAINERS entry

Md Shofiqul Islam (3):
  dt-bindings: iio: health: add maxim,max86150
  iio: health: add MAX86150 ECG and PPG biosensor driver
  MAINTAINERS: add entry for MAX86150 IIO health driver

 .../bindings/iio/health/maxim,max86150.yaml   |  67 +++
 MAINTAINERS                                   |   7 +
 drivers/iio/health/Kconfig                    |  19 +
 drivers/iio/health/Makefile                   |   1 +
 drivers/iio/health/max86150.c                 | 651 ++++++++++++++++++
 5 files changed, 745 insertions(+)

-- 
2.43.0

[PATCH v3 1/3] dt-bindings: iio: health: add maxim,max86150

[Md Shofiqul Islam]

Add YAML binding schema for the Maxim MAX86150 combined ECG and PPG
biosensor.  The device exposes two PPG optical channels (Red and IR LED)
for heart rate and SpO2 measurement, and one ECG biopotential channel, all
accessible over I2C at up to 400 kHz.

An optional active-low interrupt line connects to the 32-entry hardware
FIFO almost-full output.  Two optional regulator supplies (vdd for the
digital core and leds for the LED anodes) cover boards that require
explicit power sequencing.

Signed-off-by: Md Shofiqul Islam <shofiqtest@gmail.com>
---
 .../bindings/iio/health/maxim,max86150.yaml   | 67 +++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml

diff --git a/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml b/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
new file mode 100644
index 000000000000..1bf10fd1a3d2
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
@@ -0,0 +1,67 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/health/maxim,max86150.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Maxim MAX86150 ECG and PPG Biosensor
+
+maintainers:
+  - Md Shofiqul Islam <shofiqtest@gmail.com>
+
+description: |
+  The MAX86150 is an integrated biosensor SoC that combines:
+    - Two PPG (photoplethysmography) channels: Red LED and IR LED,
+      for heart rate and blood-oxygen saturation (SpO2) measurement.
+    - One ECG (electrocardiogram) channel for biopotential recording.
+
+  The device communicates over I2C at up to 400 kHz and raises an
+  active-low interrupt when the 32-entry hardware FIFO reaches its
+  configurable almost-full threshold.
+
+  Datasheet:
+    https://www.analog.com/media/en/technical-documentation/data-sheets/MAX86150.pdf
+
+properties:
+  compatible:
+    const: maxim,max86150
+
+  reg:
+    maxItems: 1
+    description: I2C device address, always 0x5E.
+
+  interrupts:
+    maxItems: 1
+    description: |
+      Active-low interrupt line.  Asserted when the FIFO almost-full
+      threshold is reached or when a new PPG sample is ready.
+
+  vdd-supply:
+    description: Digital core supply, 1.71 V to 1.89 V.
+
+  leds-supply:
+    description: LED anode supply, 3.0 V to 5.5 V.
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        biosensor@5e {
+            compatible = "maxim,max86150";
+            reg = <0x5e>;
+            interrupt-parent = <&gpio1>;
+            interrupts = <5 IRQ_TYPE_EDGE_FALLING>;
+            vdd-supply = <&vdd_1v8>;
+            leds-supply = <&vdd_3v3>;
+        };
+    };
-- 
2.51.1

[PATCH v3 2/3] iio: health: add MAX86150 ECG and PPG biosensor driver

[Md Shofiqul Islam]

The MAX86150 (Maxim/Analog Devices) combines two PPG optical channels
(Red/IR LED) and one ECG biopotential channel in a single I2C device with
a 32-entry hardware FIFO.

Driver features:
 - Three IIO channels: in_intensityred_raw, in_intensityir_raw, in_voltage0_raw
 - Triggered buffer path driven by the FIFO almost-full interrupt
 - set_trigger_state callback enables/disables the interrupt only while
   the buffer is active; FIFO is flushed before capture starts
 - Per-sample timestamps reconstructed from IRQ capture time and the
   configured 100 Hz sample period
 - regmap_noinc_read() burst reads into a struct-allocated (heap) buffer
   to satisfy DMA mapping requirements of I2C host controllers
 - devm_regulator_get_enable_optional() for the two optional supplies
 - Powerdown devm action disables interrupts and asserts SYS_SHDN

Signed-off-by: Md Shofiqul Islam <shofiqtest@gmail.com>
---
 drivers/iio/health/Kconfig    |  23 ++
 drivers/iio/health/Makefile   |   1 +
 drivers/iio/health/max86150.c | 651 ++++++++++++++++++++++++++++++++++
 3 files changed, 675 insertions(+)
 create mode 100644 drivers/iio/health/max86150.c

diff --git a/drivers/iio/health/Kconfig b/drivers/iio/health/Kconfig
index a89f3abf11f4..6496cf55290c 100644
--- a/drivers/iio/health/Kconfig
+++ b/drivers/iio/health/Kconfig
@@ -13,6 +13,7 @@ config AFE4403
 	depends on SPI_MASTER
 	select REGMAP_SPI
 	select IIO_BUFFER
+	select IIO_TRIGGER
 	select IIO_TRIGGERED_BUFFER
 	help
 	  Say yes to choose the Texas Instruments AFE4403
@@ -26,6 +27,7 @@ config AFE4404
 	depends on I2C
 	select REGMAP_I2C
 	select IIO_BUFFER
+	select IIO_TRIGGER
 	select IIO_TRIGGERED_BUFFER
 	help
 	  Say yes to choose the Texas Instruments AFE4404
@@ -39,6 +41,7 @@ config MAX30100
 	depends on I2C
 	select REGMAP_I2C
 	select IIO_BUFFER
+	select IIO_TRIGGER
 	select IIO_KFIFO_BUF
 	help
 	  Say Y here to build I2C interface support for the Maxim
@@ -52,6 +55,7 @@ config MAX30102
 	depends on I2C
 	select REGMAP_I2C
 	select IIO_BUFFER
+	select IIO_TRIGGER
 	select IIO_KFIFO_BUF
 	help
 	  Say Y here to build I2C interface support for the Maxim
@@ -62,4 +66,23 @@ config MAX30102
 
 endmenu
 
+
+config MAX86150
+	tristate "MAX86150 ECG and PPG biosensor"
+	depends on I2C
+	select IIO_BUFFER
+	select IIO_TRIGGER
+	select IIO_TRIGGERED_BUFFER
+	select REGMAP_I2C
+	help
+	  Say Y here to enable support for the Maxim MAX86150 combined
+	  ECG and photoplethysmography (PPG) biosensor.
+
+	  The driver exposes three IIO channels: two PPG optical channels
+	  (Red and IR LED) for heart rate and SpO2 monitoring, and one
+	  ECG channel for biopotential recording.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called max86150.
+
 endmenu
diff --git a/drivers/iio/health/Makefile b/drivers/iio/health/Makefile
index 910817112258..04fc73c58444 100644
--- a/drivers/iio/health/Makefile
+++ b/drivers/iio/health/Makefile
@@ -9,3 +9,4 @@ obj-$(CONFIG_AFE4403)		+= afe4403.o
 obj-$(CONFIG_AFE4404)		+= afe4404.o
 obj-$(CONFIG_MAX30100)		+= max30100.o
 obj-$(CONFIG_MAX30102)		+= max30102.o
+obj-$(CONFIG_MAX86150)		+= max86150.o
diff --git a/drivers/iio/health/max86150.c b/drivers/iio/health/max86150.c
new file mode 100644
index 000000000000..b6e241307646
--- /dev/null
+++ b/drivers/iio/health/max86150.c
@@ -0,0 +1,651 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MAX86150 combined ECG and PPG biosensor driver
+ *
+ * Copyright (C) 2026 Md Shofiqul Islam <shofiqtest@gmail.com>
+ *
+ * The MAX86150 integrates two PPG optical channels (Red/IR LED) and one
+ * ECG biopotential channel in a single I2C device.  Data is captured
+ * through a 32-entry hardware FIFO with a configurable almost-full
+ * interrupt, making it well-suited for continuous monitoring with a
+ * low-power host.
+ *
+ * Datasheet:
+ *   https://www.analog.com/media/en/technical-documentation/data-sheets/MAX86150.pdf
+ */
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+
+/* Register addresses */
+#define MAX86150_REG_INT_STATUS1	0x00
+#define MAX86150_REG_INT_STATUS2	0x01
+#define MAX86150_REG_INT_ENABLE1	0x02
+#define MAX86150_REG_INT_ENABLE2	0x03
+#define MAX86150_REG_FIFO_WR_PTR	0x04
+#define MAX86150_REG_OVF_COUNTER	0x05
+#define MAX86150_REG_FIFO_RD_PTR	0x06
+#define MAX86150_REG_FIFO_DATA		0x07
+#define MAX86150_REG_FIFO_CONFIG	0x08
+#define MAX86150_REG_FIFO_DCTRL1	0x09  /* FD1[3:0]  FD2[7:4] */
+#define MAX86150_REG_FIFO_DCTRL2	0x0A  /* FD3[3:0]  FD4[7:4] */
+#define MAX86150_REG_SYS_CTRL		0x0D
+#define MAX86150_REG_PPG_CONFIG1	0x10
+#define MAX86150_REG_PPG_CONFIG2	0x11
+#define MAX86150_REG_LED1_PA		0x14  /* Red LED pulse amplitude */
+#define MAX86150_REG_LED2_PA		0x15  /* IR LED pulse amplitude  */
+#define MAX86150_REG_ECG_CONFIG1	0x3C
+#define MAX86150_REG_ECG_CONFIG3	0x3E
+#define MAX86150_REG_PART_ID		0xFF
+
+/* Field masks */
+#define MAX86150_PART_ID_VAL		0x1E
+
+/* INT_STATUS1 / INT_ENABLE1 */
+#define MAX86150_INT_A_FULL		BIT(7)  /* FIFO almost full */
+#define MAX86150_INT_PPG_RDY		BIT(6)  /* new PPG sample ready */
+
+/* SYS_CTRL */
+#define MAX86150_SYS_SHDN		BIT(1)
+#define MAX86150_SYS_RESET		BIT(0)
+
+/* FIFO_CONFIG */
+#define MAX86150_FIFO_SMP_AVE		GENMASK(7, 5)
+#define MAX86150_FIFO_ROLLOVER_EN	BIT(4)
+#define MAX86150_FIFO_A_FULL		GENMASK(3, 0)
+
+/* FIFO slot data-type codes */
+#define MAX86150_FD_NONE		0x0
+#define MAX86150_FD_LED1		0x1   /* Red PPG */
+#define MAX86150_FD_LED2		0x2   /* IR PPG  */
+#define MAX86150_FD_ECG			0x9
+#define MAX86150_FIFO_FD1		GENMASK(3, 0)
+#define MAX86150_FIFO_FD2		GENMASK(7, 4)
+#define MAX86150_FIFO_FD3		GENMASK(3, 0)
+#define MAX86150_FIFO_FD4		GENMASK(7, 4)
+
+/* PPG_CONFIG1 */
+#define MAX86150_PPG_ADC_RGE		GENMASK(7, 6)
+#define MAX86150_PPG_SR			GENMASK(5, 1)
+
+/* Geometry */
+#define MAX86150_FIFO_DEPTH		32
+#define MAX86150_BYTES_PER_SLOT		3    /* 24-bit word per slot */
+#define MAX86150_NUM_SLOTS		3    /* Red, IR, ECG */
+#define MAX86150_SAMPLE_BYTES		(MAX86150_NUM_SLOTS * MAX86150_BYTES_PER_SLOT)
+
+/* Default hardware configuration */
+#define MAX86150_LED_PA_DEFAULT		0x3F  /* ~50 mA */
+#define MAX86150_PPG_SR_100HZ		4     /* PPG_SR field value for 100 Hz */
+#define MAX86150_PPG_ADC_RGE_16384	2     /* 16384 nA full scale */
+/* Fire A_FULL when 17 slots remain (32 - 15 = 17 samples in FIFO) */
+#define MAX86150_FIFO_A_FULL_VAL	15
+
+/* Scan element indices */
+enum max86150_scan_idx {
+	MAX86150_IDX_PPG_RED = 0,
+	MAX86150_IDX_PPG_IR  = 1,
+	MAX86150_IDX_ECG     = 2,
+	MAX86150_IDX_TS,
+};
+
+/**
+ * struct max86150_data - driver private state
+ * @regmap:           register map for this device
+ * @dev:              parent device (for dev_err logging)
+ * @trig:             IIO hardware trigger backed by the device interrupt line
+ * @sample_period_ns: sample period in nanoseconds (set from configured rate)
+ * @fifo_raw:         DMA-safe buffer for regmap_noinc_read() FIFO bursts;
+ *                    must be in struct (heap) not on the stack to satisfy
+ *                    DMA mapping requirements of some I2C host controllers
+ * @buf:              IIO push buffer sized for worst-case (all 3 channels
+ *                    active): 3 x s32 (12 bytes) + 4-byte pad + s64
+ *                    timestamp = 24 bytes.  __aligned(8) satisfies
+ *                    iio_push_to_buffers_with_timestamp().
+ */
+struct max86150_data {
+	struct regmap		*regmap;
+	struct device		*dev;
+	struct iio_trigger	*trig;
+	u32			 sample_period_ns;
+	u8			 fifo_raw[MAX86150_SAMPLE_BYTES];
+	s32 buf[6] __aligned(8);
+};
+
+/* IIO channel specification */
+
+static const struct iio_chan_spec max86150_channels[] = {
+	{
+		/* PPG Red LED - optical intensity, 19-bit unsigned */
+		.type               = IIO_INTENSITY,
+		.modified           = 1,
+		.channel2           = IIO_MOD_LIGHT_RED,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.scan_index         = MAX86150_IDX_PPG_RED,
+		.scan_type = {
+			.sign        = 'u',
+			.realbits    = 19,
+			.storagebits = 32,
+			.endianness  = IIO_CPU,
+		},
+	},
+	{
+		/* PPG IR LED - optical intensity, 19-bit unsigned */
+		.type               = IIO_INTENSITY,
+		.modified           = 1,
+		.channel2           = IIO_MOD_LIGHT_IR,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.scan_index         = MAX86150_IDX_PPG_IR,
+		.scan_type = {
+			.sign        = 'u',
+			.realbits    = 19,
+			.storagebits = 32,
+			.endianness  = IIO_CPU,
+		},
+	},
+	{
+		/* ECG biopotential - voltage, 18-bit signed two's complement */
+		.type               = IIO_VOLTAGE,
+		.channel            = 0,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.scan_index         = MAX86150_IDX_ECG,
+		.scan_type = {
+			.sign        = 's',
+			.realbits    = 18,
+			.storagebits = 32,
+			.endianness  = IIO_CPU,
+		},
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(MAX86150_IDX_TS),
+};
+
+/* Regmap configuration */
+
+static const struct regmap_config max86150_regmap_config = {
+	.reg_bits     = 8,
+	.val_bits     = 8,
+	.max_register = MAX86150_REG_PART_ID,
+};
+
+/* FIFO helper */
+
+/**
+ * max86150_read_one_sample - burst-read one complete 3-slot FIFO entry
+ * @data:    driver state
+ * @ppg_red: out - 19-bit PPG Red ADC value (unsigned)
+ * @ppg_ir:  out - 19-bit PPG IR ADC value (unsigned)
+ * @ecg:     out - 18-bit ECG ADC value (sign-extended to s32)
+ *
+ * Each FIFO entry is 9 bytes (3 slots x 3 bytes).  FIFO_DATA is a
+ * streaming register - the address does not auto-increment on each
+ * byte, so regmap_noinc_read() is used instead of regmap_bulk_read().
+ *
+ * Byte layout in the 24-bit FIFO word (MSB first):
+ *   PPG 19-bit unsigned: bits [18:0], top 5 bits are always zero
+ *   ECG 18-bit signed:   bits [17:0], top 6 bits are sign extension
+ */
+static int max86150_read_one_sample(struct max86150_data *data,
+				    u32 *ppg_red, u32 *ppg_ir, s32 *ecg)
+{
+	int ret;
+
+	/*
+	 * Use data->fifo_raw (heap memory) not a local array so the buffer is
+	 * DMA-mappable for I2C host controllers that use DMA for burst reads.
+	 */
+	ret = regmap_noinc_read(data->regmap, MAX86150_REG_FIFO_DATA,
+				data->fifo_raw, sizeof(data->fifo_raw));
+	if (ret)
+		return ret;
+
+	/* Bytes [0..2]: PPG Red - 19-bit value in bits [18:0] */
+	*ppg_red = (u32)(data->fifo_raw[0] & 0x07) << 16 |
+		   (u32)data->fifo_raw[1] << 8 | data->fifo_raw[2];
+
+	/* Bytes [3..5]: PPG IR - same format */
+	*ppg_ir  = (u32)(data->fifo_raw[3] & 0x07) << 16 |
+		   (u32)data->fifo_raw[4] << 8 | data->fifo_raw[5];
+
+	/* Bytes [6..8]: ECG - 18-bit signed, sign-extend to s32 */
+	*ecg = sign_extend32((u32)(data->fifo_raw[6] & 0x03) << 16 |
+			     (u32)data->fifo_raw[7] << 8 | data->fifo_raw[8], 17);
+
+	return 0;
+}
+
+/* IIO read_raw */
+
+static int max86150_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)
+{
+	struct max86150_data *data = iio_priv(indio_dev);
+	u32 ppg_red, ppg_ir;
+	s32 ecg;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		/*
+		 * Claim direct mode to prevent concurrent sysfs reads from
+		 * corrupting the FIFO pointers while a triggered buffer
+		 * capture is active.
+		 */
+		if (!iio_device_claim_direct(indio_dev))
+			return -EBUSY;
+
+		/*
+		 * Single-shot path: reset FIFO pointers so the next sample
+		 * read is one that arrived after this call.
+		 */
+		ret = regmap_write(data->regmap, MAX86150_REG_FIFO_WR_PTR, 0);
+		if (!ret)
+			ret = regmap_write(data->regmap,
+					   MAX86150_REG_OVF_COUNTER, 0);
+		if (!ret)
+			ret = regmap_write(data->regmap,
+					   MAX86150_REG_FIFO_RD_PTR, 0);
+		if (ret) {
+			iio_device_release_direct(indio_dev);
+			return ret;
+		}
+
+		/* Wait for one complete sample period at 100 Hz (<= 10 ms) */
+		usleep_range(11000, 13000);
+
+		ret = max86150_read_one_sample(data, &ppg_red, &ppg_ir, &ecg);
+		iio_device_release_direct(indio_dev);
+		if (ret)
+			return ret;
+
+		switch (chan->scan_index) {
+		case MAX86150_IDX_PPG_RED:
+			*val = ppg_red;
+			break;
+		case MAX86150_IDX_PPG_IR:
+			*val = ppg_ir;
+			break;
+		case MAX86150_IDX_ECG:
+			*val = ecg;
+			break;
+		default:
+			return -EINVAL;
+		}
+		return IIO_VAL_INT;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info max86150_iio_info = {
+	.read_raw = max86150_read_raw,
+};
+
+/* Trigger */
+
+/*
+ * Enable or disable the FIFO almost-full interrupt when the IIO triggered
+ * buffer is started or stopped.  Keeping the interrupt masked until capture
+ * is active prevents a pre-existing FIFO fill from asserting the line before
+ * the handler is ready to clear it.
+ */
+static int max86150_set_trigger_state(struct iio_trigger *trig, bool state)
+{
+	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
+	struct max86150_data *data = iio_priv(indio_dev);
+	unsigned int mask = state ? MAX86150_INT_A_FULL : 0;
+	int ret;
+
+	if (state) {
+		/*
+		 * Flush stale FIFO data before enabling capture so the first
+		 * samples pushed to userspace are not from before buffer enable.
+		 */
+		ret = regmap_write(data->regmap, MAX86150_REG_FIFO_WR_PTR, 0);
+		if (ret)
+			return ret;
+		ret = regmap_write(data->regmap, MAX86150_REG_OVF_COUNTER, 0);
+		if (ret)
+			return ret;
+		ret = regmap_write(data->regmap, MAX86150_REG_FIFO_RD_PTR, 0);
+		if (ret)
+			return ret;
+	}
+
+	return regmap_write(data->regmap, MAX86150_REG_INT_ENABLE1, mask);
+}
+
+static const struct iio_trigger_ops max86150_trigger_ops = {
+	.set_trigger_state = max86150_set_trigger_state,
+};
+
+/* Triggered buffer */
+
+/**
+ * max86150_trigger_handler - threaded IRQ handler for FIFO almost-full
+ *
+ * Called by the IIO buffer infrastructure when the hardware trigger fires.
+ * Reads INT_STATUS1 to de-assert the interrupt, then drains all available
+ * FIFO samples into the IIO push buffer, packing only the channels that
+ * are currently enabled in active_scan_mask.
+ */
+static irqreturn_t max86150_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func	*pf   = p;
+	struct iio_dev		*idev = pf->indio_dev;
+	struct max86150_data	*data = iio_priv(idev);
+	unsigned int status, wr_ptr, rd_ptr, ovf;
+	u32 ppg_red, ppg_ir;
+	s32 ecg;
+	int ret, n_avail, i, j;
+
+	/*
+	 * Reading INT_STATUS1 clears the interrupt.  Do this before touching
+	 * the FIFO so the pin is de-asserted while we drain samples.
+	 */
+	ret = regmap_read(data->regmap, MAX86150_REG_INT_STATUS1, &status);
+	if (ret)
+		goto done;
+
+	ret = regmap_read(data->regmap, MAX86150_REG_FIFO_WR_PTR, &wr_ptr);
+	if (ret)
+		goto done;
+	ret = regmap_read(data->regmap, MAX86150_REG_FIFO_RD_PTR, &rd_ptr);
+	if (ret)
+		goto done;
+
+	/*
+	 * Read OVF_COUNTER to distinguish a full FIFO from an empty one:
+	 * both produce wr_ptr == rd_ptr after the pointers wrap around.
+	 * If OVF_COUNTER is non-zero the FIFO has saturated; treat all 32
+	 * slots as available so we drain the entire FIFO and clear the
+	 * interrupt condition.
+	 */
+	ret = regmap_read(data->regmap, MAX86150_REG_OVF_COUNTER, &ovf);
+	if (ret)
+		goto done;
+
+	if (ovf > 0)
+		n_avail = MAX86150_FIFO_DEPTH;
+	else
+		n_avail = (wr_ptr - rd_ptr) & (MAX86150_FIFO_DEPTH - 1);
+
+	/*
+	 * Reconstruct per-sample timestamps from the IRQ capture time.
+	 * iio_pollfunc_store_time() stored the IRQ time in pf->timestamp;
+	 * that corresponds to the newest sample in the FIFO.  Older samples
+	 * are spaced by sample_period_ns going backward in time.
+	 */
+	for (i = 0; i < n_avail; i++) {
+		s64 ts = pf->timestamp -
+			 (s64)(n_avail - 1 - i) * data->sample_period_ns;
+
+		ret = max86150_read_one_sample(data, &ppg_red, &ppg_ir, &ecg);
+		if (ret)
+			break;
+
+		/*
+		 * Zero the entire buffer before packing so padding bytes
+		 * between enabled channels do not leak previous sample data
+		 * to userspace when fewer than 3 channels are active.
+		 */
+		memset(data->buf, 0, sizeof(data->buf));
+
+		/*
+		 * Pack only active channels at consecutive positions [0..j-1].
+		 * iio_push_to_buffers_with_timestamp() uses scan_bytes (which
+		 * accounts for the active channel count) to place the timestamp,
+		 * so static indexing would misplace it when fewer than 3
+		 * channels are enabled.
+		 */
+		j = 0;
+		if (test_bit(MAX86150_IDX_PPG_RED, idev->active_scan_mask))
+			data->buf[j++] = ppg_red;
+		if (test_bit(MAX86150_IDX_PPG_IR, idev->active_scan_mask))
+			data->buf[j++] = ppg_ir;
+		if (test_bit(MAX86150_IDX_ECG, idev->active_scan_mask))
+			data->buf[j++] = ecg;
+
+		iio_push_to_buffers_with_timestamp(idev, data->buf, ts);
+	}
+
+done:
+	iio_trigger_notify_done(idev->trig);
+	return IRQ_HANDLED;
+}
+
+/* Chip initialisation / teardown */
+
+static void max86150_powerdown(void *arg)
+{
+	struct max86150_data *data = arg;
+
+	regmap_write(data->regmap, MAX86150_REG_INT_ENABLE1, 0);
+	regmap_write(data->regmap, MAX86150_REG_SYS_CTRL, MAX86150_SYS_SHDN);
+}
+
+static int max86150_chip_init(struct max86150_data *data)
+{
+	int ret;
+
+	/* Software reset; the bit self-clears within 1 ms */
+	ret = regmap_write(data->regmap, MAX86150_REG_SYS_CTRL,
+			   MAX86150_SYS_RESET);
+	if (ret)
+		return ret;
+	usleep_range(1000, 2000);
+
+	/*
+	 * FIFO: no sample averaging, rollover enabled, assert A_FULL when
+	 * 17 samples are in the FIFO (32 - 15 = 17 available to read).
+	 */
+	ret = regmap_write(data->regmap, MAX86150_REG_FIFO_CONFIG,
+			   MAX86150_FIFO_ROLLOVER_EN |
+			   FIELD_PREP(MAX86150_FIFO_A_FULL,
+				      MAX86150_FIFO_A_FULL_VAL));
+	if (ret)
+		return ret;
+
+	/* Slot 1 = PPG Red (LED1), Slot 2 = PPG IR (LED2) */
+	ret = regmap_write(data->regmap, MAX86150_REG_FIFO_DCTRL1,
+			   FIELD_PREP(MAX86150_FIFO_FD1, MAX86150_FD_LED1) |
+			   FIELD_PREP(MAX86150_FIFO_FD2, MAX86150_FD_LED2));
+	if (ret)
+		return ret;
+
+	/* Slot 3 = ECG, Slot 4 = disabled */
+	ret = regmap_write(data->regmap, MAX86150_REG_FIFO_DCTRL2,
+			   FIELD_PREP(MAX86150_FIFO_FD3, MAX86150_FD_ECG) |
+			   FIELD_PREP(MAX86150_FIFO_FD4, MAX86150_FD_NONE));
+	if (ret)
+		return ret;
+
+	/* PPG: 100 Hz sample rate, 16384 nA ADC full-scale range */
+	ret = regmap_write(data->regmap, MAX86150_REG_PPG_CONFIG1,
+			   FIELD_PREP(MAX86150_PPG_ADC_RGE,
+				      MAX86150_PPG_ADC_RGE_16384) |
+			   FIELD_PREP(MAX86150_PPG_SR,
+				      MAX86150_PPG_SR_100HZ));
+	if (ret)
+		return ret;
+
+	/* LED pulse amplitudes (~50 mA) */
+	ret = regmap_write(data->regmap, MAX86150_REG_LED1_PA,
+			   MAX86150_LED_PA_DEFAULT);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(data->regmap, MAX86150_REG_LED2_PA,
+			   MAX86150_LED_PA_DEFAULT);
+	if (ret)
+		return ret;
+
+	/*
+	 * Record sample period for timestamp reconstruction in the trigger
+	 * handler.  The PPG_SR field is fixed to 100 Hz in this driver.
+	 */
+	data->sample_period_ns = 10000000; /* 100 Hz = 10 ms */
+
+	/*
+	 * Do NOT enable the A_FULL interrupt here.  It is enabled and
+	 * disabled via max86150_set_trigger_state() when the IIO triggered
+	 * buffer is started and stopped, which prevents the edge-triggered
+	 * interrupt line from asserting before the handler is registered.
+	 */
+	return 0;
+}
+
+/* Probe */
+
+static int max86150_probe(struct i2c_client *client)
+{
+	struct iio_dev		*indio_dev;
+	struct max86150_data	*data;
+	unsigned int		 part_id;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data      = iio_priv(indio_dev);
+	data->dev = &client->dev;
+
+	/*
+	 * Enable power supplies before any I2C access.  Both supplies are
+	 * optional in the device tree; use _optional variant so probing
+	 * succeeds on boards that power the device from fixed rails with no
+	 * DT regulator node.
+	 */
+	ret = devm_regulator_get_enable_optional(&client->dev, "vdd");
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Failed to get/enable vdd supply\n");
+
+	ret = devm_regulator_get_enable_optional(&client->dev, "leds");
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Failed to get/enable leds supply\n");
+
+	data->regmap = devm_regmap_init_i2c(client, &max86150_regmap_config);
+	if (IS_ERR(data->regmap))
+		return dev_err_probe(&client->dev, PTR_ERR(data->regmap),
+				     "Failed to initialise regmap\n");
+
+	ret = regmap_read(data->regmap, MAX86150_REG_PART_ID, &part_id);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Cannot read part ID\n");
+
+	if (part_id != MAX86150_PART_ID_VAL)
+		return dev_err_probe(&client->dev, -ENODEV,
+				     "Unexpected part ID 0x%02x (expected 0x%02x)\n",
+				     part_id, MAX86150_PART_ID_VAL);
+
+	ret = max86150_chip_init(data);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Chip initialisation failed\n");
+
+	ret = devm_add_action_or_reset(&client->dev, max86150_powerdown, data);
+	if (ret)
+		return ret;
+
+	indio_dev->name         = "max86150";
+	indio_dev->channels     = max86150_channels;
+	indio_dev->num_channels = ARRAY_SIZE(max86150_channels);
+	indio_dev->info         = &max86150_iio_info;
+	indio_dev->modes        = INDIO_DIRECT_MODE;
+
+	/*
+	 * If the device tree provides an interrupt, set up a hardware
+	 * trigger so userspace can use the FIFO almost-full signal to
+	 * drive capture without polling.
+	 */
+	if (client->irq > 0) {
+		data->trig = devm_iio_trigger_alloc(&client->dev,
+						    "%s-dev%d",
+						    indio_dev->name,
+						    iio_device_id(indio_dev));
+		if (!data->trig)
+			return -ENOMEM;
+
+		data->trig->ops = &max86150_trigger_ops;
+		iio_trigger_set_drvdata(data->trig, indio_dev);
+
+		/*
+		 * iio_trigger_generic_data_rdy_poll is a hard-IRQ handler
+		 * that calls iio_trigger_poll() and returns IRQ_HANDLED.
+		 * No IRQF_ONESHOT is needed for this edge-triggered line.
+		 */
+		ret = devm_request_irq(&client->dev, client->irq,
+				       iio_trigger_generic_data_rdy_poll,
+				       IRQF_TRIGGER_FALLING,
+				       "max86150", data->trig);
+		if (ret)
+			return dev_err_probe(&client->dev, ret,
+					     "Cannot request IRQ %d\n",
+					     client->irq);
+
+		ret = devm_iio_trigger_register(&client->dev, data->trig);
+		if (ret)
+			return dev_err_probe(&client->dev, ret,
+					     "Cannot register trigger\n");
+
+		/*
+		 * Set the device's default trigger.  iio_trigger_get()
+		 * increments the trigger refcount; the IIO core balances
+		 * this with iio_trigger_put() in iio_dev_release() when
+		 * the iio_dev is freed.  No additional devm action needed.
+		 */
+		indio_dev->trig = iio_trigger_get(data->trig);
+	}
+
+	ret = devm_iio_triggered_buffer_setup(&client->dev, indio_dev,
+					      iio_pollfunc_store_time,
+					      max86150_trigger_handler,
+					      NULL);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Cannot setup triggered buffer\n");
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+/* I2C driver table */
+
+static const struct i2c_device_id max86150_id[] = {
+	{ "max86150" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max86150_id);
+
+static const struct of_device_id max86150_of_match[] = {
+	{ .compatible = "maxim,max86150" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max86150_of_match);
+
+static struct i2c_driver max86150_driver = {
+	.driver = {
+		.name           = "max86150",
+		.of_match_table = max86150_of_match,
+	},
+	.probe    = max86150_probe,
+	.id_table = max86150_id,
+};
+module_i2c_driver(max86150_driver);
+
+MODULE_AUTHOR("Md Shofiqul Islam <shofiqtest@gmail.com>");
+MODULE_DESCRIPTION("MAX86150 ECG and PPG biosensor driver");
+MODULE_LICENSE("GPL");
-- 
2.51.1

[PATCH v3 3/3] MAINTAINERS: add entry for MAX86150 IIO health driver

[Md Shofiqul Islam]

Add a MAINTAINERS entry for the new MAX86150 ECG and PPG biosensor driver,
covering both the driver and its DT binding schema.

Signed-off-by: Md Shofiqul Islam <shofiqtest@gmail.com>
---
 MAINTAINERS | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 3115538ce829..a441ec44bb27 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15863,6 +15863,13 @@ S:	Supported
 F:	Documentation/devicetree/bindings/power/supply/maxim,max77976.yaml
 F:	drivers/power/supply/max77976_charger.c
 
+MAXIM MAX86150 ECG AND PPG BIOSENSOR DRIVER
+M:	Md Shofiqul Islam <shofiqtest@gmail.com>
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
+F:	drivers/iio/health/max86150.c
+
 MAXIM MUIC CHARGER DRIVERS FOR EXYNOS BASED BOARDS
 M:	Krzysztof Kozlowski <krzk@kernel.org>
 L:	linux-pm@vger.kernel.org
-- 
2.51.1

[PATCH v4 0/3] iio: health: add MAX86150 ECG and PPG biosensor driver

[Md Shofiqul Islam]

Changes in v4 (addressing Sashiko review of v3):

- [High] Fix optional regulator probe failure: treat -ENODEV from
  devm_regulator_get_enable_optional() as success (supply absent,
  not an error).

- [High] Align fifo_raw to ARCH_DMA_MINALIGN to satisfy DMA mapping
  requirements of I2C host controllers that use DMA for burst transfers.

- [High] Disambiguate FIFO empty vs exactly-full: when wr_ptr == rd_ptr
  with OVF_COUNTER == 0, consult the A_FULL interrupt status bit to
  determine whether the FIFO pointer wrapped to full or is truly empty.

- [High] Remove iio_trigger_get() in probe: the incremented refcount
  leaks on the error path when devm_iio_device_register() fails because
  iio_device_unregister() (and its paired iio_trigger_put()) never runs.
  Users set the trigger via the current_trigger sysfs attribute as normal.

- [High] Assert SYS_SHDN in chip_init() so the LED drivers draw no
  current while capture is inactive.  set_trigger_state() clears SHDN
  when the buffer is enabled and re-asserts it when disabled.
  read_raw() wakes and sleeps the device around each single-shot read.

- [Medium] Replace IRQF_TRIGGER_FALLING with irq_get_trigger_type() to
  honour the interrupt trigger type from the device tree; falls back to
  falling-edge if the DT does not specify one.

- [Medium] Add .validate_trigger = iio_trigger_validate_own_device to
  prevent incompatible external triggers from being attached.

- [Medium] Fix per-sample timestamp jitter: anchor timestamps to the
  A_FULL IRQ capture time.  The sample at index (A_FULL_SAMPLES - 1)
  corresponds to pf->timestamp; samples accumulated between the IRQ and
  handler execution receive future timestamps, eliminating scheduling-
  latency-dependent jitter in multi-sample drains.

Link: https://lore.kernel.org/linux-iio/20260623155556.13701-1-shofiqtest@gmail.com/
  v3 cover letter

Md Shofiqul Islam (3):
  dt-bindings: iio: health: add maxim,max86150
  iio: health: add MAX86150 ECG and PPG biosensor driver
  MAINTAINERS: add entry for MAX86150 IIO health driver

-- 
2.49.0

[PATCH v4 1/3] dt-bindings: iio: health: add maxim,max86150

[Md Shofiqul Islam]

Add YAML binding schema for the Maxim MAX86150 combined ECG and PPG
biosensor.  The device exposes two PPG optical channels (Red and IR LED)
for heart rate and SpO2 measurement, and one ECG biopotential channel, all
accessible over I2C at up to 400 kHz.

An optional active-low interrupt line connects to the 32-entry hardware
FIFO almost-full output.  Two optional regulator supplies (vdd for the
digital core and leds for the LED anodes) cover boards that require
explicit power sequencing.

Signed-off-by: Md Shofiqul Islam <shofiqtest@gmail.com>
---
 .../bindings/iio/health/maxim,max86150.yaml   | 67 +++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml

diff --git a/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml b/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
new file mode 100644
index 000000000000..1bf10fd1a3d2
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
@@ -0,0 +1,67 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/health/maxim,max86150.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Maxim MAX86150 ECG and PPG Biosensor
+
+maintainers:
+  - Md Shofiqul Islam <shofiqtest@gmail.com>
+
+description: |
+  The MAX86150 is an integrated biosensor SoC that combines:
+    - Two PPG (photoplethysmography) channels: Red LED and IR LED,
+      for heart rate and blood-oxygen saturation (SpO2) measurement.
+    - One ECG (electrocardiogram) channel for biopotential recording.
+
+  The device communicates over I2C at up to 400 kHz and raises an
+  active-low interrupt when the 32-entry hardware FIFO reaches its
+  configurable almost-full threshold.
+
+  Datasheet:
+    https://www.analog.com/media/en/technical-documentation/data-sheets/MAX86150.pdf
+
+properties:
+  compatible:
+    const: maxim,max86150
+
+  reg:
+    maxItems: 1
+    description: I2C device address, always 0x5E.
+
+  interrupts:
+    maxItems: 1
+    description: |
+      Active-low interrupt line.  Asserted when the FIFO almost-full
+      threshold is reached or when a new PPG sample is ready.
+
+  vdd-supply:
+    description: Digital core supply, 1.71 V to 1.89 V.
+
+  leds-supply:
+    description: LED anode supply, 3.0 V to 5.5 V.
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        biosensor@5e {
+            compatible = "maxim,max86150";
+            reg = <0x5e>;
+            interrupt-parent = <&gpio1>;
+            interrupts = <5 IRQ_TYPE_EDGE_FALLING>;
+            vdd-supply = <&vdd_1v8>;
+            leds-supply = <&vdd_3v3>;
+        };
+    };
-- 
2.51.1

[PATCH v4 2/3] iio: health: add MAX86150 ECG and PPG biosensor driver

[Md Shofiqul Islam]

The MAX86150 (Maxim/Analog Devices) combines two PPG optical channels
(Red/IR LED) and one ECG biopotential channel in a single I2C device with
a 32-entry hardware FIFO.

Driver features:
 - Three IIO channels: in_intensityred_raw, in_intensityir_raw,
   in_voltage0_raw
 - Triggered buffer path driven by the FIFO almost-full interrupt;
   set_trigger_state enables/disables the interrupt only while the buffer
   is active and FIFO is flushed before capture starts
 - validate_trigger = iio_trigger_validate_own_device prevents
   incompatible external triggers from being attached
 - IRQ trigger type taken from irq_get_trigger_type() to honour DT
   configuration; falls back to falling-edge if unspecified
 - fifo_raw burst-read buffer is heap-allocated in struct max86150_data
   and aligned to ARCH_DMA_MINALIGN to satisfy DMA mapping requirements
   of I2C host controllers that use DMA for burst reads
 - SYS_SHDN asserted at end of chip_init so LED drivers draw no current
   when capture is inactive; set_trigger_state() and read_raw() wake and
   sleep the device on demand
 - Per-sample timestamps anchored to the A_FULL IRQ capture time: the
   sample at index (A_FULL_SAMPLES - 1) maps to pf->timestamp, samples
   accumulated after the IRQ receive future timestamps, eliminating
   load-dependent jitter
 - FIFO empty vs exactly-full disambiguation: when wr_ptr == rd_ptr with
   OVF_COUNTER == 0, the A_FULL status bit distinguishes a pointer
   wrap-around (full) from a genuinely empty FIFO
 - devm_regulator_get_enable_optional() for the two optional supplies;
   -ENODEV is treated as success (supply absent, not an error)
 - Powerdown devm action disables interrupts and asserts SYS_SHDN

Signed-off-by: Md Shofiqul Islam <shofiqtest@gmail.com>
---
 drivers/iio/health/Kconfig    |  23 ++
 drivers/iio/health/Makefile   |   1 +
 drivers/iio/health/max86150.c | 677 ++++++++++++++++++++++++++++++++++
 3 files changed, 701 insertions(+)
 create mode 100644 drivers/iio/health/max86150.c

diff --git a/drivers/iio/health/Kconfig b/drivers/iio/health/Kconfig
index a89f3abf11f4..6496cf55290c 100644
--- a/drivers/iio/health/Kconfig
+++ b/drivers/iio/health/Kconfig
@@ -13,6 +13,7 @@ config AFE4403
 	depends on SPI_MASTER
 	select REGMAP_SPI
 	select IIO_BUFFER
+	select IIO_TRIGGER
 	select IIO_TRIGGERED_BUFFER
 	help
 	  Say yes to choose the Texas Instruments AFE4403
@@ -26,6 +27,7 @@ config AFE4404
 	depends on I2C
 	select REGMAP_I2C
 	select IIO_BUFFER
+	select IIO_TRIGGER
 	select IIO_TRIGGERED_BUFFER
 	help
 	  Say yes to choose the Texas Instruments AFE4404
@@ -39,6 +41,7 @@ config MAX30100
 	depends on I2C
 	select REGMAP_I2C
 	select IIO_BUFFER
+	select IIO_TRIGGER
 	select IIO_KFIFO_BUF
 	help
 	  Say Y here to build I2C interface support for the Maxim
@@ -52,6 +55,7 @@ config MAX30102
 	depends on I2C
 	select REGMAP_I2C
 	select IIO_BUFFER
+	select IIO_TRIGGER
 	select IIO_KFIFO_BUF
 	help
 	  Say Y here to build I2C interface support for the Maxim
@@ -62,4 +66,23 @@ config MAX30102
 
 endmenu
 
+
+config MAX86150
+	tristate "MAX86150 ECG and PPG biosensor"
+	depends on I2C
+	select IIO_BUFFER
+	select IIO_TRIGGER
+	select IIO_TRIGGERED_BUFFER
+	select REGMAP_I2C
+	help
+	  Say Y here to enable support for the Maxim MAX86150 combined
+	  ECG and photoplethysmography (PPG) biosensor.
+
+	  The driver exposes three IIO channels: two PPG optical channels
+	  (Red and IR LED) for heart rate and SpO2 monitoring, and one
+	  ECG channel for biopotential recording.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called max86150.
+
 endmenu
diff --git a/drivers/iio/health/Makefile b/drivers/iio/health/Makefile
index 910817112258..04fc73c58444 100644
--- a/drivers/iio/health/Makefile
+++ b/drivers/iio/health/Makefile
@@ -9,3 +9,4 @@ obj-$(CONFIG_AFE4403)		+= afe4403.o
 obj-$(CONFIG_AFE4404)		+= afe4404.o
 obj-$(CONFIG_MAX30100)		+= max30100.o
 obj-$(CONFIG_MAX30102)		+= max30102.o
+obj-$(CONFIG_MAX86150)		+= max86150.o
diff --git a/drivers/iio/health/max86150.c b/drivers/iio/health/max86150.c
new file mode 100644
index 000000000000..0140c93bd4ec
--- /dev/null
+++ b/drivers/iio/health/max86150.c
@@ -0,0 +1,677 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MAX86150 combined ECG and PPG biosensor driver
+ *
+ * Copyright (C) 2026 Md Shofiqul Islam <shofiqtest@gmail.com>
+ *
+ * The MAX86150 integrates two PPG optical channels (Red/IR LED) and one
+ * ECG biopotential channel in a single I2C device.  Data is captured
+ * through a 32-entry hardware FIFO with a configurable almost-full
+ * interrupt, making it well-suited for continuous monitoring with a
+ * low-power host.
+ *
+ * Datasheet:
+ *   https://www.analog.com/media/en/technical-documentation/data-sheets/MAX86150.pdf
+ */
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/irq.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+
+/* Register addresses */
+#define MAX86150_REG_INT_STATUS1	0x00
+#define MAX86150_REG_INT_STATUS2	0x01
+#define MAX86150_REG_INT_ENABLE1	0x02
+#define MAX86150_REG_INT_ENABLE2	0x03
+#define MAX86150_REG_FIFO_WR_PTR	0x04
+#define MAX86150_REG_OVF_COUNTER	0x05
+#define MAX86150_REG_FIFO_RD_PTR	0x06
+#define MAX86150_REG_FIFO_DATA		0x07
+#define MAX86150_REG_FIFO_CONFIG	0x08
+#define MAX86150_REG_FIFO_DCTRL1	0x09  /* FD1[3:0]  FD2[7:4] */
+#define MAX86150_REG_FIFO_DCTRL2	0x0A  /* FD3[3:0]  FD4[7:4] */
+#define MAX86150_REG_SYS_CTRL		0x0D
+#define MAX86150_REG_PPG_CONFIG1	0x10
+#define MAX86150_REG_PPG_CONFIG2	0x11
+#define MAX86150_REG_LED1_PA		0x14  /* Red LED pulse amplitude */
+#define MAX86150_REG_LED2_PA		0x15  /* IR LED pulse amplitude  */
+#define MAX86150_REG_ECG_CONFIG1	0x3C
+#define MAX86150_REG_ECG_CONFIG3	0x3E
+#define MAX86150_REG_PART_ID		0xFF
+
+/* Field masks */
+#define MAX86150_PART_ID_VAL		0x1E
+
+/* INT_STATUS1 / INT_ENABLE1 */
+#define MAX86150_INT_A_FULL		BIT(7)  /* FIFO almost full */
+#define MAX86150_INT_PPG_RDY		BIT(6)  /* new PPG sample ready */
+
+/* SYS_CTRL */
+#define MAX86150_SYS_SHDN		BIT(1)
+#define MAX86150_SYS_RESET		BIT(0)
+
+/* FIFO_CONFIG */
+#define MAX86150_FIFO_SMP_AVE		GENMASK(7, 5)
+#define MAX86150_FIFO_ROLLOVER_EN	BIT(4)
+#define MAX86150_FIFO_A_FULL		GENMASK(3, 0)
+
+/* FIFO slot data-type codes */
+#define MAX86150_FD_NONE		0x0
+#define MAX86150_FD_LED1		0x1   /* Red PPG */
+#define MAX86150_FD_LED2		0x2   /* IR PPG  */
+#define MAX86150_FD_ECG			0x9
+#define MAX86150_FIFO_FD1		GENMASK(3, 0)
+#define MAX86150_FIFO_FD2		GENMASK(7, 4)
+#define MAX86150_FIFO_FD3		GENMASK(3, 0)
+#define MAX86150_FIFO_FD4		GENMASK(7, 4)
+
+/* PPG_CONFIG1 */
+#define MAX86150_PPG_ADC_RGE		GENMASK(7, 6)
+#define MAX86150_PPG_SR			GENMASK(5, 1)
+
+/* Geometry */
+#define MAX86150_FIFO_DEPTH		32
+#define MAX86150_BYTES_PER_SLOT		3    /* 24-bit word per slot */
+#define MAX86150_NUM_SLOTS		3    /* Red, IR, ECG */
+#define MAX86150_SAMPLE_BYTES		(MAX86150_NUM_SLOTS * MAX86150_BYTES_PER_SLOT)
+/* Samples present in the FIFO when the A_FULL interrupt fires */
+#define MAX86150_A_FULL_SAMPLES		(MAX86150_FIFO_DEPTH - MAX86150_FIFO_A_FULL_VAL)
+
+/* Default hardware configuration */
+#define MAX86150_LED_PA_DEFAULT		0x3F  /* ~50 mA */
+#define MAX86150_PPG_SR_100HZ		4     /* PPG_SR field value for 100 Hz */
+#define MAX86150_PPG_ADC_RGE_16384	2     /* 16384 nA full scale */
+/* Fire A_FULL when 17 slots remain (32 - 15 = 17 samples in FIFO) */
+#define MAX86150_FIFO_A_FULL_VAL	15
+
+/* Scan element indices */
+enum max86150_scan_idx {
+	MAX86150_IDX_PPG_RED = 0,
+	MAX86150_IDX_PPG_IR  = 1,
+	MAX86150_IDX_ECG     = 2,
+	MAX86150_IDX_TS,
+};
+
+/**
+ * struct max86150_data - driver private state
+ * @regmap:           register map for this device
+ * @dev:              parent device (for dev_err logging)
+ * @trig:             IIO hardware trigger backed by the device interrupt line
+ * @sample_period_ns: sample period in nanoseconds (set from configured rate)
+ * @fifo_raw:         DMA-safe buffer for regmap_noinc_read() FIFO bursts;
+ *                    must be in struct (heap) not on the stack to satisfy
+ *                    DMA mapping requirements of some I2C host controllers
+ * @buf:              IIO push buffer sized for worst-case (all 3 channels
+ *                    active): 3 x s32 (12 bytes) + 4-byte pad + s64
+ *                    timestamp = 24 bytes.  __aligned(8) satisfies
+ *                    iio_push_to_buffers_with_timestamp().
+ */
+struct max86150_data {
+	struct regmap		*regmap;
+	struct device		*dev;
+	struct iio_trigger	*trig;
+	u32			 sample_period_ns;
+	u8			 fifo_raw[MAX86150_SAMPLE_BYTES] __aligned(ARCH_DMA_MINALIGN);
+	s32 buf[6] __aligned(8);
+};
+
+/* IIO channel specification */
+
+static const struct iio_chan_spec max86150_channels[] = {
+	{
+		/* PPG Red LED - optical intensity, 19-bit unsigned */
+		.type               = IIO_INTENSITY,
+		.modified           = 1,
+		.channel2           = IIO_MOD_LIGHT_RED,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.scan_index         = MAX86150_IDX_PPG_RED,
+		.scan_type = {
+			.sign        = 'u',
+			.realbits    = 19,
+			.storagebits = 32,
+			.endianness  = IIO_CPU,
+		},
+	},
+	{
+		/* PPG IR LED - optical intensity, 19-bit unsigned */
+		.type               = IIO_INTENSITY,
+		.modified           = 1,
+		.channel2           = IIO_MOD_LIGHT_IR,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.scan_index         = MAX86150_IDX_PPG_IR,
+		.scan_type = {
+			.sign        = 'u',
+			.realbits    = 19,
+			.storagebits = 32,
+			.endianness  = IIO_CPU,
+		},
+	},
+	{
+		/* ECG biopotential - voltage, 18-bit signed two's complement */
+		.type               = IIO_VOLTAGE,
+		.channel            = 0,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.scan_index         = MAX86150_IDX_ECG,
+		.scan_type = {
+			.sign        = 's',
+			.realbits    = 18,
+			.storagebits = 32,
+			.endianness  = IIO_CPU,
+		},
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(MAX86150_IDX_TS),
+};
+
+/* Regmap configuration */
+
+static const struct regmap_config max86150_regmap_config = {
+	.reg_bits     = 8,
+	.val_bits     = 8,
+	.max_register = MAX86150_REG_PART_ID,
+};
+
+/* FIFO helper */
+
+/**
+ * max86150_read_one_sample - burst-read one complete 3-slot FIFO entry
+ * @data:    driver state
+ * @ppg_red: out - 19-bit PPG Red ADC value (unsigned)
+ * @ppg_ir:  out - 19-bit PPG IR ADC value (unsigned)
+ * @ecg:     out - 18-bit ECG ADC value (sign-extended to s32)
+ *
+ * Each FIFO entry is 9 bytes (3 slots x 3 bytes).  FIFO_DATA is a
+ * streaming register - the address does not auto-increment on each
+ * byte, so regmap_noinc_read() is used instead of regmap_bulk_read().
+ *
+ * Byte layout in the 24-bit FIFO word (MSB first):
+ *   PPG 19-bit unsigned: bits [18:0], top 5 bits are always zero
+ *   ECG 18-bit signed:   bits [17:0], top 6 bits are sign extension
+ */
+static int max86150_read_one_sample(struct max86150_data *data,
+				    u32 *ppg_red, u32 *ppg_ir, s32 *ecg)
+{
+	int ret;
+
+	/*
+	 * Use data->fifo_raw (heap memory) not a local array so the buffer is
+	 * DMA-mappable for I2C host controllers that use DMA for burst reads.
+	 */
+	ret = regmap_noinc_read(data->regmap, MAX86150_REG_FIFO_DATA,
+				data->fifo_raw, sizeof(data->fifo_raw));
+	if (ret)
+		return ret;
+
+	/* Bytes [0..2]: PPG Red - 19-bit value in bits [18:0] */
+	*ppg_red = (u32)(data->fifo_raw[0] & 0x07) << 16 |
+		   (u32)data->fifo_raw[1] << 8 | data->fifo_raw[2];
+
+	/* Bytes [3..5]: PPG IR - same format */
+	*ppg_ir  = (u32)(data->fifo_raw[3] & 0x07) << 16 |
+		   (u32)data->fifo_raw[4] << 8 | data->fifo_raw[5];
+
+	/* Bytes [6..8]: ECG - 18-bit signed, sign-extend to s32 */
+	*ecg = sign_extend32((u32)(data->fifo_raw[6] & 0x03) << 16 |
+			     (u32)data->fifo_raw[7] << 8 | data->fifo_raw[8], 17);
+
+	return 0;
+}
+
+/* IIO read_raw */
+
+static int max86150_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)
+{
+	struct max86150_data *data = iio_priv(indio_dev);
+	u32 ppg_red, ppg_ir;
+	s32 ecg;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		/*
+		 * Claim direct mode to prevent concurrent sysfs reads from
+		 * corrupting the FIFO pointers while a triggered buffer
+		 * capture is active.
+		 */
+		if (!iio_device_claim_direct(indio_dev))
+			return -EBUSY;
+
+		/*
+		 * Single-shot path: wake the device, flush stale FIFO data,
+		 * wait one sample period, read, then return to shutdown so
+		 * the LEDs are not drawing current when idle.
+		 */
+		ret = regmap_update_bits(data->regmap, MAX86150_REG_SYS_CTRL,
+					 MAX86150_SYS_SHDN, 0);
+		if (!ret)
+			ret = regmap_write(data->regmap,
+					   MAX86150_REG_FIFO_WR_PTR, 0);
+		if (!ret)
+			ret = regmap_write(data->regmap,
+					   MAX86150_REG_OVF_COUNTER, 0);
+		if (!ret)
+			ret = regmap_write(data->regmap,
+					   MAX86150_REG_FIFO_RD_PTR, 0);
+		if (ret) {
+			regmap_update_bits(data->regmap, MAX86150_REG_SYS_CTRL,
+					   MAX86150_SYS_SHDN, MAX86150_SYS_SHDN);
+			iio_device_release_direct(indio_dev);
+			return ret;
+		}
+
+		/* Wait for one complete sample period at 100 Hz (<= 10 ms) */
+		usleep_range(11000, 13000);
+
+		ret = max86150_read_one_sample(data, &ppg_red, &ppg_ir, &ecg);
+		regmap_update_bits(data->regmap, MAX86150_REG_SYS_CTRL,
+				   MAX86150_SYS_SHDN, MAX86150_SYS_SHDN);
+		iio_device_release_direct(indio_dev);
+		if (ret)
+			return ret;
+
+		switch (chan->scan_index) {
+		case MAX86150_IDX_PPG_RED:
+			*val = ppg_red;
+			break;
+		case MAX86150_IDX_PPG_IR:
+			*val = ppg_ir;
+			break;
+		case MAX86150_IDX_ECG:
+			*val = ecg;
+			break;
+		default:
+			return -EINVAL;
+		}
+		return IIO_VAL_INT;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info max86150_iio_info = {
+	.read_raw         = max86150_read_raw,
+	.validate_trigger = iio_trigger_validate_own_device,
+};
+
+/* Trigger */
+
+/*
+ * Control device power and the FIFO almost-full interrupt when the IIO
+ * triggered buffer is started (state=true) or stopped (state=false).
+ *
+ * On start: wake from shutdown, flush stale FIFO data so the first
+ * samples pushed to userspace are from after buffer enable, then
+ * unmask the A_FULL interrupt.
+ *
+ * On stop: mask the interrupt, then return to shutdown so the LED
+ * drivers do not draw current while capture is inactive.
+ */
+static int max86150_set_trigger_state(struct iio_trigger *trig, bool state)
+{
+	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
+	struct max86150_data *data = iio_priv(indio_dev);
+	int ret;
+
+	if (!state) {
+		ret = regmap_write(data->regmap, MAX86150_REG_INT_ENABLE1, 0);
+		regmap_update_bits(data->regmap, MAX86150_REG_SYS_CTRL,
+				   MAX86150_SYS_SHDN, MAX86150_SYS_SHDN);
+		return ret;
+	}
+
+	ret = regmap_update_bits(data->regmap, MAX86150_REG_SYS_CTRL,
+				 MAX86150_SYS_SHDN, 0);
+	if (!ret)
+		ret = regmap_write(data->regmap, MAX86150_REG_FIFO_WR_PTR, 0);
+	if (!ret)
+		ret = regmap_write(data->regmap, MAX86150_REG_OVF_COUNTER, 0);
+	if (!ret)
+		ret = regmap_write(data->regmap, MAX86150_REG_FIFO_RD_PTR, 0);
+	if (!ret)
+		ret = regmap_write(data->regmap, MAX86150_REG_INT_ENABLE1,
+				   MAX86150_INT_A_FULL);
+	if (ret)
+		regmap_update_bits(data->regmap, MAX86150_REG_SYS_CTRL,
+				   MAX86150_SYS_SHDN, MAX86150_SYS_SHDN);
+	return ret;
+}
+
+static const struct iio_trigger_ops max86150_trigger_ops = {
+	.set_trigger_state = max86150_set_trigger_state,
+};
+
+/* Triggered buffer */
+
+/**
+ * max86150_trigger_handler - threaded IRQ handler for FIFO almost-full
+ *
+ * Called by the IIO buffer infrastructure when the hardware trigger fires.
+ * Reads INT_STATUS1 to de-assert the interrupt, then drains all available
+ * FIFO samples into the IIO push buffer, packing only the channels that
+ * are currently enabled in active_scan_mask.
+ */
+static irqreturn_t max86150_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func	*pf   = p;
+	struct iio_dev		*idev = pf->indio_dev;
+	struct max86150_data	*data = iio_priv(idev);
+	unsigned int status, wr_ptr, rd_ptr, ovf;
+	u32 ppg_red, ppg_ir;
+	s32 ecg;
+	int ret, n_avail, i, j;
+
+	/*
+	 * Reading INT_STATUS1 clears the interrupt.  Do this before touching
+	 * the FIFO so the pin is de-asserted while we drain samples.
+	 */
+	ret = regmap_read(data->regmap, MAX86150_REG_INT_STATUS1, &status);
+	if (ret)
+		goto done;
+
+	ret = regmap_read(data->regmap, MAX86150_REG_FIFO_WR_PTR, &wr_ptr);
+	if (ret)
+		goto done;
+	ret = regmap_read(data->regmap, MAX86150_REG_FIFO_RD_PTR, &rd_ptr);
+	if (ret)
+		goto done;
+
+	/*
+	 * OVF_COUNTER: if non-zero the FIFO overflowed; drain all 32 slots.
+	 * When wr_ptr == rd_ptr with no overflow the FIFO could be empty OR
+	 * hold exactly MAX86150_FIFO_DEPTH entries (pointer wrap-around).
+	 * Use the A_FULL status bit to disambiguate: if the IRQ fired for
+	 * A_FULL but the computed count is zero, the FIFO wrapped to full.
+	 */
+	ret = regmap_read(data->regmap, MAX86150_REG_OVF_COUNTER, &ovf);
+	if (ret)
+		goto done;
+
+	if (ovf > 0) {
+		n_avail = MAX86150_FIFO_DEPTH;
+	} else {
+		n_avail = (wr_ptr - rd_ptr) & (MAX86150_FIFO_DEPTH - 1);
+		if (n_avail == 0 && (status & MAX86150_INT_A_FULL))
+			n_avail = MAX86150_FIFO_DEPTH;
+	}
+
+	/*
+	 * Anchor timestamps to the A_FULL IRQ capture time: sample index
+	 * (MAX86150_A_FULL_SAMPLES - 1) corresponds to pf->timestamp.
+	 * Samples that accumulated between the IRQ and handler execution
+	 * receive timestamps in the future relative to the IRQ, eliminating
+	 * load-dependent jitter in multi-sample drains.
+	 */
+	for (i = 0; i < n_avail; i++) {
+		s64 ts = pf->timestamp +
+			 (s64)(i - (MAX86150_A_FULL_SAMPLES - 1)) *
+			 data->sample_period_ns;
+
+		ret = max86150_read_one_sample(data, &ppg_red, &ppg_ir, &ecg);
+		if (ret)
+			break;
+
+		/*
+		 * Zero the entire buffer before packing so padding bytes
+		 * between enabled channels do not leak previous sample data
+		 * to userspace when fewer than 3 channels are active.
+		 */
+		memset(data->buf, 0, sizeof(data->buf));
+
+		/*
+		 * Pack only active channels at consecutive positions [0..j-1].
+		 * iio_push_to_buffers_with_timestamp() uses scan_bytes (which
+		 * accounts for the active channel count) to place the timestamp,
+		 * so static indexing would misplace it when fewer than 3
+		 * channels are enabled.
+		 */
+		j = 0;
+		if (test_bit(MAX86150_IDX_PPG_RED, idev->active_scan_mask))
+			data->buf[j++] = ppg_red;
+		if (test_bit(MAX86150_IDX_PPG_IR, idev->active_scan_mask))
+			data->buf[j++] = ppg_ir;
+		if (test_bit(MAX86150_IDX_ECG, idev->active_scan_mask))
+			data->buf[j++] = ecg;
+
+		iio_push_to_buffers_with_timestamp(idev, data->buf, ts);
+	}
+
+done:
+	iio_trigger_notify_done(idev->trig);
+	return IRQ_HANDLED;
+}
+
+/* Chip initialisation / teardown */
+
+static void max86150_powerdown(void *arg)
+{
+	struct max86150_data *data = arg;
+
+	regmap_write(data->regmap, MAX86150_REG_INT_ENABLE1, 0);
+	regmap_write(data->regmap, MAX86150_REG_SYS_CTRL, MAX86150_SYS_SHDN);
+}
+
+static int max86150_chip_init(struct max86150_data *data)
+{
+	int ret;
+
+	/* Software reset; the bit self-clears within 1 ms */
+	ret = regmap_write(data->regmap, MAX86150_REG_SYS_CTRL,
+			   MAX86150_SYS_RESET);
+	if (ret)
+		return ret;
+	usleep_range(1000, 2000);
+
+	/*
+	 * FIFO: no sample averaging, rollover enabled, assert A_FULL when
+	 * 17 samples are in the FIFO (32 - 15 = 17 available to read).
+	 */
+	ret = regmap_write(data->regmap, MAX86150_REG_FIFO_CONFIG,
+			   MAX86150_FIFO_ROLLOVER_EN |
+			   FIELD_PREP(MAX86150_FIFO_A_FULL,
+				      MAX86150_FIFO_A_FULL_VAL));
+	if (ret)
+		return ret;
+
+	/* Slot 1 = PPG Red (LED1), Slot 2 = PPG IR (LED2) */
+	ret = regmap_write(data->regmap, MAX86150_REG_FIFO_DCTRL1,
+			   FIELD_PREP(MAX86150_FIFO_FD1, MAX86150_FD_LED1) |
+			   FIELD_PREP(MAX86150_FIFO_FD2, MAX86150_FD_LED2));
+	if (ret)
+		return ret;
+
+	/* Slot 3 = ECG, Slot 4 = disabled */
+	ret = regmap_write(data->regmap, MAX86150_REG_FIFO_DCTRL2,
+			   FIELD_PREP(MAX86150_FIFO_FD3, MAX86150_FD_ECG) |
+			   FIELD_PREP(MAX86150_FIFO_FD4, MAX86150_FD_NONE));
+	if (ret)
+		return ret;
+
+	/* PPG: 100 Hz sample rate, 16384 nA ADC full-scale range */
+	ret = regmap_write(data->regmap, MAX86150_REG_PPG_CONFIG1,
+			   FIELD_PREP(MAX86150_PPG_ADC_RGE,
+				      MAX86150_PPG_ADC_RGE_16384) |
+			   FIELD_PREP(MAX86150_PPG_SR,
+				      MAX86150_PPG_SR_100HZ));
+	if (ret)
+		return ret;
+
+	/* LED pulse amplitudes (~50 mA) */
+	ret = regmap_write(data->regmap, MAX86150_REG_LED1_PA,
+			   MAX86150_LED_PA_DEFAULT);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(data->regmap, MAX86150_REG_LED2_PA,
+			   MAX86150_LED_PA_DEFAULT);
+	if (ret)
+		return ret;
+
+	/*
+	 * Record sample period for timestamp reconstruction in the trigger
+	 * handler.  The PPG_SR field is fixed to 100 Hz in this driver.
+	 */
+	data->sample_period_ns = 10000000; /* 100 Hz = 10 ms */
+
+	/*
+	 * Assert SYS_SHDN so the LED drivers do not draw current while
+	 * the driver is bound but no capture is active.
+	 * set_trigger_state() clears SHDN when the IIO buffer is enabled
+	 * and re-asserts it when disabled.  read_raw() wakes and sleeps
+	 * the device around each single-shot read.
+	 */
+	return regmap_write(data->regmap, MAX86150_REG_SYS_CTRL,
+			    MAX86150_SYS_SHDN);
+}
+
+/* Probe */
+
+static int max86150_probe(struct i2c_client *client)
+{
+	struct iio_dev		*indio_dev;
+	struct max86150_data	*data;
+	unsigned int		 part_id;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data      = iio_priv(indio_dev);
+	data->dev = &client->dev;
+
+	/*
+	 * Enable power supplies before any I2C access.  Both supplies are
+	 * optional in the device tree; use _optional variant so probing
+	 * succeeds on boards that power the device from fixed rails with no
+	 * DT regulator node.
+	 */
+	ret = devm_regulator_get_enable_optional(&client->dev, "vdd");
+	if (ret && ret != -ENODEV)
+		return dev_err_probe(&client->dev, ret,
+				     "Failed to get/enable vdd supply\n");
+
+	ret = devm_regulator_get_enable_optional(&client->dev, "leds");
+	if (ret && ret != -ENODEV)
+		return dev_err_probe(&client->dev, ret,
+				     "Failed to get/enable leds supply\n");
+
+	data->regmap = devm_regmap_init_i2c(client, &max86150_regmap_config);
+	if (IS_ERR(data->regmap))
+		return dev_err_probe(&client->dev, PTR_ERR(data->regmap),
+				     "Failed to initialise regmap\n");
+
+	ret = regmap_read(data->regmap, MAX86150_REG_PART_ID, &part_id);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Cannot read part ID\n");
+
+	if (part_id != MAX86150_PART_ID_VAL)
+		return dev_err_probe(&client->dev, -ENODEV,
+				     "Unexpected part ID 0x%02x (expected 0x%02x)\n",
+				     part_id, MAX86150_PART_ID_VAL);
+
+	ret = max86150_chip_init(data);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Chip initialisation failed\n");
+
+	ret = devm_add_action_or_reset(&client->dev, max86150_powerdown, data);
+	if (ret)
+		return ret;
+
+	indio_dev->name         = "max86150";
+	indio_dev->channels     = max86150_channels;
+	indio_dev->num_channels = ARRAY_SIZE(max86150_channels);
+	indio_dev->info         = &max86150_iio_info;
+	indio_dev->modes        = INDIO_DIRECT_MODE;
+
+	/*
+	 * If the device tree provides an interrupt, set up a hardware
+	 * trigger so userspace can use the FIFO almost-full signal to
+	 * drive capture without polling.
+	 */
+	if (client->irq > 0) {
+		unsigned long irq_trig;
+
+		data->trig = devm_iio_trigger_alloc(&client->dev,
+						    "%s-dev%d",
+						    indio_dev->name,
+						    iio_device_id(indio_dev));
+		if (!data->trig)
+			return -ENOMEM;
+
+		data->trig->ops = &max86150_trigger_ops;
+		iio_trigger_set_drvdata(data->trig, indio_dev);
+
+		/*
+		 * Honour the interrupt trigger type from the device tree.
+		 * Fall back to falling-edge if the DT does not specify one.
+		 */
+		irq_trig = irq_get_trigger_type(client->irq);
+		if (!irq_trig)
+			irq_trig = IRQF_TRIGGER_FALLING;
+
+		ret = devm_request_irq(&client->dev, client->irq,
+				       iio_trigger_generic_data_rdy_poll,
+				       irq_trig,
+				       "max86150", data->trig);
+		if (ret)
+			return dev_err_probe(&client->dev, ret,
+					     "Cannot request IRQ %d\n",
+					     client->irq);
+
+		ret = devm_iio_trigger_register(&client->dev, data->trig);
+		if (ret)
+			return dev_err_probe(&client->dev, ret,
+					     "Cannot register trigger\n");
+	}
+
+	ret = devm_iio_triggered_buffer_setup(&client->dev, indio_dev,
+					      iio_pollfunc_store_time,
+					      max86150_trigger_handler,
+					      NULL);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Cannot setup triggered buffer\n");
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+/* I2C driver table */
+
+static const struct i2c_device_id max86150_id[] = {
+	{ "max86150" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max86150_id);
+
+static const struct of_device_id max86150_of_match[] = {
+	{ .compatible = "maxim,max86150" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max86150_of_match);
+
+static struct i2c_driver max86150_driver = {
+	.driver = {
+		.name           = "max86150",
+		.of_match_table = max86150_of_match,
+	},
+	.probe    = max86150_probe,
+	.id_table = max86150_id,
+};
+module_i2c_driver(max86150_driver);
+
+MODULE_AUTHOR("Md Shofiqul Islam <shofiqtest@gmail.com>");
+MODULE_DESCRIPTION("MAX86150 ECG and PPG biosensor driver");
+MODULE_LICENSE("GPL");
-- 
2.51.1

[PATCH v4 3/3] MAINTAINERS: add entry for MAX86150 IIO health driver

[Md Shofiqul Islam]

Add a MAINTAINERS entry for the new MAX86150 ECG and PPG biosensor driver,
covering both the driver and its DT binding schema.

Signed-off-by: Md Shofiqul Islam <shofiqtest@gmail.com>
---
 MAINTAINERS | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 3115538ce829..a441ec44bb27 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15863,6 +15863,13 @@ S:	Supported
 F:	Documentation/devicetree/bindings/power/supply/maxim,max77976.yaml
 F:	drivers/power/supply/max77976_charger.c
 
+MAXIM MAX86150 ECG AND PPG BIOSENSOR DRIVER
+M:	Md Shofiqul Islam <shofiqtest@gmail.com>
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
+F:	drivers/iio/health/max86150.c
+
 MAXIM MUIC CHARGER DRIVERS FOR EXYNOS BASED BOARDS
 M:	Krzysztof Kozlowski <krzk@kernel.org>
 L:	linux-pm@vger.kernel.org
-- 
2.51.1

Re: [PATCH v3 1/3] dt-bindings: iio: health: add maxim,max86150

[Conor Dooley]

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On Tue, Jun 23, 2026 at 07:43:07PM +0300, Md Shofiqul Islam wrote:
> Add YAML binding schema for the Maxim MAX86150 combined ECG and PPG
> biosensor.  The device exposes two PPG optical channels (Red and IR LED)
> for heart rate and SpO2 measurement, and one ECG biopotential channel, all
> accessible over I2C at up to 400 kHz.
> 
> An optional active-low interrupt line connects to the 32-entry hardware
> FIFO almost-full output.  Two optional regulator supplies (vdd for the
> digital core and leds for the LED anodes) cover boards that require
> explicit power sequencing.
> 
> Signed-off-by: Md Shofiqul Islam <shofiqtest@gmail.com>
> ---
>  .../bindings/iio/health/maxim,max86150.yaml   | 67 +++++++++++++++++++
>  1 file changed, 67 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
> 
> diff --git a/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml b/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
> new file mode 100644
> index 000000000000..1bf10fd1a3d2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/health/maxim,max86150.yaml
> @@ -0,0 +1,67 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/health/maxim,max86150.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Maxim MAX86150 ECG and PPG Biosensor
> +
> +maintainers:
> +  - Md Shofiqul Islam <shofiqtest@gmail.com>
> +
> +description: |
> +  The MAX86150 is an integrated biosensor SoC that combines:
> +    - Two PPG (photoplethysmography) channels: Red LED and IR LED,
> +      for heart rate and blood-oxygen saturation (SpO2) measurement.
> +    - One ECG (electrocardiogram) channel for biopotential recording.
> +
> +  The device communicates over I2C at up to 400 kHz and raises an
> +  active-low interrupt when the 32-entry hardware FIFO reaches its
> +  configurable almost-full threshold.
> +
> +  Datasheet:
> +    https://www.analog.com/media/en/technical-documentation/data-sheets/MAX86150.pdf
> +
> +properties:
> +  compatible:
> +    const: maxim,max86150

ADI would like the prefix for newly added former maxim products to be
"adi,".

> +
> +  reg:
> +    maxItems: 1
> +    description: I2C device address, always 0x5E.
> +
> +  interrupts:
> +    maxItems: 1
> +    description: |
> +      Active-low interrupt line.  Asserted when the FIFO almost-full
> +      threshold is reached or when a new PPG sample is ready.
> +
> +  vdd-supply:
> +    description: Digital core supply, 1.71 V to 1.89 V.

This is a 1.8v supply, the tolerances on it don't need to be mentioned
here.

> +  leds-supply:
> +    description: LED anode supply, 3.0 V to 5.5 V.

Datasheet cites 5v as the max for this, not 5.5v, with a typical value of
3.3v. Makes me think that 3.3 is the intended value, since using a 5v
supply could easily fluctuate over the maximum rated value.

Looks like there's more supplies than this?
I see:
Vdd_ana
Vdd_dig
Vref
Vled

Additionally, these supplies should be mandatory.

pw-bot: changes-requested

> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        biosensor@5e {

Seems to be prior art for calling things like this "heart-rate",
although that is somewhat limited compared to what this device can do.

Cheers,
Conor.

> +            compatible = "maxim,max86150";
> +            reg = <0x5e>;
> +            interrupt-parent = <&gpio1>;
> +            interrupts = <5 IRQ_TYPE_EDGE_FALLING>;
> +            vdd-supply = <&vdd_1v8>;
> +            leds-supply = <&vdd_3v3>;
> +        };
> +    };
> -- 
> 2.51.1
> 

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