[PATCH] iio: light: add driver support for MAX44009

[Robert Eshleman <bobbyeshleman@gmail.com>]

The MAX44009 is a low-power ambient light sensor from Maxim Integrated.
It differs from the MAX44000 in that it doesn't have proximity sensing and that
it requires far less current (1 micro-amp vs 5 micro-amps). The register
mapping and feature set between the two are different enough to require a new
driver for the MAX44009.

Developed and tested with a BeagleBone Black and UDOO Neo (i.MX6SX)

Supported features:

* Rising and falling illuminance threshold
  events

* Illuminance triggered buffers

* Integration time

https://datasheets.maximintegrated.com/en/ds/MAX44009.pdf

Signed-off-by: Robert Eshleman <bobbyeshleman@gmail.com>
---
 .../bindings/iio/light/max44009.txt           |  25 +
 drivers/iio/light/Kconfig                     |  13 +
 drivers/iio/light/Makefile                    |   1 +
 drivers/iio/light/max44009.c                  | 696 ++++++++++++++++++
 4 files changed, 735 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/light/max44009.txt
 create mode 100644 drivers/iio/light/max44009.c

diff --git a/Documentation/devicetree/bindings/iio/light/max44009.txt b/Documentation/devicetree/bindings/iio/light/max44009.txt
new file mode 100644
index 000000000000..220c2808dca1
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/light/max44009.txt
@@ -0,0 +1,25 @@
+* MAX44009 Ambient Light Sensor
+
+Required properties:
+
+- compatible: should be "maxim,max44009"
+- reg: the I2C address of the device (default is <0x4a>)
+
+Optional properties:
+
+- interrupts : interrupt mapping for GPIO IRQ. Should be configured with
+  IRQ_TYPE_EDGE_FALLING.
+
+Refer to interrupt-controller/interrupts.txt for generic interrupt client
+node bindings.
+
+Example:
+
+max44009: max44009@4a {
+	compatible = "maxim,max44009";
+	reg = <0x4a>;
+
+	interrupt-parent = <&gpio1>;
+	interrupts = <17 IRQ_TYPE_EDGE_FALLING>;
+};
+
diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
index 36f458433480..cda544f1047d 100644
--- a/drivers/iio/light/Kconfig
+++ b/drivers/iio/light/Kconfig
@@ -299,6 +299,19 @@ config MAX44000
 	 To compile this driver as a module, choose M here:
 	 the module will be called max44000.
 
+config MAX44009
+	tristate "MAX44009 Ambient Light Sensor"
+	depends on I2C
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	select IIO_TRIGGERED_EVENT
+	help
+	 Say Y here if you want to build support for Maxim Integrated's
+	 MAX44009 ambient light sensor device.
+
+	 To compile this driver as a module, choose M here:
+	 the module will be called max44009.
+
 config OPT3001
 	tristate "Texas Instruments OPT3001 Light Sensor"
 	depends on I2C
diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
index 286bf3975372..e40794fbb435 100644
--- a/drivers/iio/light/Makefile
+++ b/drivers/iio/light/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_SENSORS_LM3533)	+= lm3533-als.o
 obj-$(CONFIG_LTR501)		+= ltr501.o
 obj-$(CONFIG_LV0104CS)		+= lv0104cs.o
 obj-$(CONFIG_MAX44000)		+= max44000.o
+obj-$(CONFIG_MAX44009)		+= max44009.o
 obj-$(CONFIG_OPT3001)		+= opt3001.o
 obj-$(CONFIG_PA12203001)	+= pa12203001.o
 obj-$(CONFIG_RPR0521)		+= rpr0521.o
diff --git a/drivers/iio/light/max44009.c b/drivers/iio/light/max44009.c
new file mode 100644
index 000000000000..e15aa8eeb2f6
--- /dev/null
+++ b/drivers/iio/light/max44009.c
@@ -0,0 +1,696 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * max44009.c - Support for MAX44009 Ambient Light Sensor
+ *
+ * Copyright (c) 2019 Robert Eshleman <bobbyeshleman@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ *
+ * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX44009.pdf
+ *
+ * TODO: Support continuous mode and processed event value (IIO_EV_INFO_VALUE)
+ *
+ * Default I2C address: 0x4a
+ *
+ */
+
+#include <linux/bits.h>
+#include <linux/i2c.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/events.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/util_macros.h>
+
+#define MAX44009_DRV_NAME "max44009"
+#define MAX44009_IRQ_NAME "max44009_event"
+
+/* Registers in datasheet order */
+#define MAX44009_REG_STATUS 0x0
+#define MAX44009_REG_ENABLE 0x1
+#define MAX44009_REG_CFG 0x2
+#define MAX44009_REG_LUX_HI 0x3
+#define MAX44009_REG_LUX_LO 0x4
+#define MAX44009_REG_UPPER_THR 0x5
+#define MAX44009_REG_LOWER_THR 0x6
+#define MAX44009_REG_THR_TIMER 0x7
+
+#define MAX44009_INT_TIME_MASK (BIT(2) | BIT(1) | BIT(0))
+#define MAX44009_INT_TIME_SHIFT (0)
+
+#define MAX44009_MANUAL_MODE_MASK BIT(6)
+
+/* The maxmimum raw rising threshold for the max44009 */
+#define MAX44009_MAXIMUM_THRESHOLD 8355840
+
+#define MAX44009_HI_NIBBLE(reg) (((reg) >> 4) & 0xf)
+#define MAX44009_LO_NIBBLE(reg) ((reg) & 0xf)
+
+#define MAX44009_EXP_MASK 0xf00
+#define MAX44009_EXP_RSHIFT 8
+#define MAX44009_LUX_EXP(reg)	                                              \
+	(1 << (((reg) & MAX44009_EXP_MASK) >> MAX44009_EXP_RSHIFT))
+#define MAX44009_LUX_MANT(reg) ((reg) & 0xff)
+
+#define MAX44009_LUX(reg) (MAX44009_LUX_EXP(reg) * MAX44009_LUX_MANT(reg))
+
+#define MAX44009_THRESH_MANT(reg) ((MAX44009_LO_NIBBLE(reg) << 4) + 15)
+#define MAX44009_THRESHOLD(reg)                                                \
+	((1 << MAX44009_HI_NIBBLE(reg)) * MAX44009_THRESH_MANT(reg))
+
+static const u32 max44009_int_time_ns_array[] = {
+	800000000,
+	400000000,
+	200000000,
+	100000000,
+	50000000, /* Manual mode only */
+	25000000, /* Manual mode only */
+	12500000, /* Manual mode only */
+	6250000,  /* Manual mode only */
+};
+
+static const char max44009_int_time_str[] =
+	"0.8 "
+	"0.4 "
+	"0.2 "
+	"0.1 "
+	"0.05 "
+	"0.025 "
+	"0.0125 "
+	"0.00625";
+
+static const u8 max44009_scale_avail_ulux_array[] = {45};
+static const char max44009_scale_avail_str[] = "0.045";
+
+struct max44009_data {
+	struct i2c_client *client;
+	struct iio_trigger *trigger;
+	struct mutex lock;
+	int64_t timestamp;
+};
+
+static const struct iio_event_spec max44009_event_spec[] = {
+	{
+		.type = IIO_EV_TYPE_THRESH,
+		.dir = IIO_EV_DIR_RISING,
+		.mask_separate = BIT(IIO_EV_INFO_VALUE) |
+				 BIT(IIO_EV_INFO_ENABLE),
+	},
+	{
+		.type = IIO_EV_TYPE_THRESH,
+		.dir = IIO_EV_DIR_FALLING,
+		.mask_separate = BIT(IIO_EV_INFO_VALUE) |
+				 BIT(IIO_EV_INFO_ENABLE),
+	},
+};
+
+static const struct iio_chan_spec max44009_channels[] = {
+	{
+		.type = IIO_LIGHT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_INT_TIME),
+		.scan_index = 0,
+		.scan_type = {
+				.sign = 'u',
+				.realbits = 24,
+				.storagebits = 32,
+			},
+		.event_spec = max44009_event_spec,
+		.num_event_specs = ARRAY_SIZE(max44009_event_spec),
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+static int max44009_read_reg(struct max44009_data *data, char reg)
+{
+	struct i2c_client *client = data->client;
+	int ret;
+
+	mutex_lock(&data->lock);
+	ret = i2c_smbus_read_byte_data(client, reg);
+	if (ret < 0) {
+		dev_err(&client->dev,
+			"failed to read reg 0x%0x, err: %d\n", reg, ret);
+		goto err;
+	}
+
+err:
+	mutex_unlock(&data->lock);
+	return ret;
+}
+
+static int max44009_write_reg(struct max44009_data *data, char reg, char buf)
+{
+	struct i2c_client *client = data->client;
+	int ret;
+
+	mutex_lock(&data->lock);
+	ret = i2c_smbus_write_byte_data(client, reg, buf);
+	if (ret < 0) {
+		dev_err(&client->dev,
+			"failed to write reg 0x%0x, err: %d\n",
+			reg, ret);
+		goto err;
+	}
+
+err:
+	mutex_unlock(&data->lock);
+	return ret;
+}
+
+static int max44009_read_int_time(struct max44009_data *data)
+{
+	int ret = max44009_read_reg(data, MAX44009_REG_CFG);
+
+	if (ret < 0) {
+		return ret;
+	}
+
+	return max44009_int_time_ns_array[ret & MAX44009_INT_TIME_MASK];
+}
+
+static int max44009_write_raw(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan, int val,
+			      int val2, long mask)
+{
+	struct max44009_data *data = iio_priv(indio_dev);
+	int ret, int_time;
+	s64 ns;
+
+	if (mask == IIO_CHAN_INFO_INT_TIME && chan->type == IIO_LIGHT) {
+		ns = val * NSEC_PER_SEC + val2;
+		int_time = find_closest_descending(
+				ns,
+				max44009_int_time_ns_array,
+				ARRAY_SIZE(max44009_int_time_ns_array));
+
+		ret = max44009_read_reg(data, MAX44009_REG_CFG);
+		if (ret < 0)
+			return ret;
+
+		ret &= ~MAX44009_INT_TIME_MASK;
+		ret |= (int_time << MAX44009_INT_TIME_SHIFT);
+		ret |= MAX44009_MANUAL_MODE_MASK;
+
+		return max44009_write_reg(data, MAX44009_REG_CFG, ret);
+	}
+	return -EINVAL;
+}
+
+static int max44009_write_raw_get_fmt(struct iio_dev *indio_dev,
+				      struct iio_chan_spec const *chan,
+				      long mask)
+{
+	if (mask == IIO_CHAN_INFO_INT_TIME && chan->type == IIO_LIGHT) {
+		return IIO_VAL_INT_PLUS_NANO;
+	} else {
+		return IIO_VAL_INT;
+	}
+}
+
+#define READ_LUX_XFER_LEN (4)
+
+static int max44009_read_lux_raw(struct max44009_data *data)
+{
+	int ret;
+	struct i2c_msg xfer[READ_LUX_XFER_LEN];
+	u8 luxhireg[1] = {MAX44009_REG_LUX_HI};
+	u8 luxloreg[1] = {MAX44009_REG_LUX_LO};
+	u8 lo = 0;
+	u8 hi = 0;
+	u16 reg = 0;
+
+	xfer[0].addr = data->client->addr;
+	xfer[0].flags = 0;
+	xfer[0].len = 1;
+	xfer[0].buf = luxhireg;
+
+	xfer[1].addr = data->client->addr;
+	xfer[1].flags = I2C_M_RD;
+	xfer[1].len = 1;
+	xfer[1].buf = &hi;
+
+	xfer[2].addr = data->client->addr;
+	xfer[2].flags = 0;
+	xfer[2].len = 1;
+	xfer[2].buf = luxloreg;
+
+	xfer[3].addr = data->client->addr;
+	xfer[3].flags = I2C_M_RD;
+	xfer[3].len = 1;
+	xfer[3].buf = &lo;
+
+	/*
+	 * Use i2c_transfer instead of smbus read because i2c_transfer
+	 * does NOT use a stop bit between address write and data read.
+	 * Using a stop bit causes disjoint upper/lower byte reads and
+	 * reduces accuracy
+	 */
+	mutex_lock(&data->lock);
+	ret = i2c_transfer(data->client->adapter, xfer, READ_LUX_XFER_LEN);
+	mutex_unlock(&data->lock);
+	if (ret != READ_LUX_XFER_LEN) {
+		return -EIO;
+	}
+
+	reg = (((u16)hi) << 4) | (lo & 0xf);
+
+	return MAX44009_LUX(reg);
+}
+
+static int max44009_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan, int *val,
+			     int *val2, long mask)
+{
+	struct max44009_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW: {
+		switch (chan->type) {
+		case IIO_LIGHT: {
+			ret = max44009_read_lux_raw(data);
+			if (ret < 0) {
+				return ret;
+			}
+			*val = ret;
+			*val2 = 0;
+			return IIO_VAL_INT;
+		}
+		default:
+			return -EINVAL;
+		}
+		break;
+	}
+
+	case IIO_CHAN_INFO_INT_TIME: {
+		ret = max44009_read_int_time(data);
+		if (ret < 0) {
+			return ret;
+		}
+
+		*val2 = ret;
+		*val = 0;
+		return IIO_VAL_INT_PLUS_NANO;
+	}
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static IIO_CONST_ATTR(illuminance_scale_available, max44009_scale_avail_str);
+static IIO_CONST_ATTR(illuminance_integration_time_available,
+		      max44009_int_time_str);
+
+static struct attribute *max44009_attributes[] = {
+	&iio_const_attr_illuminance_integration_time_available.dev_attr.attr,
+	&iio_const_attr_illuminance_scale_available.dev_attr.attr, NULL
+};
+
+static const struct attribute_group max44009_attribute_group = {
+	.attrs = max44009_attributes,
+};
+
+static int max44009_thresh_byte_from_int(int thresh)
+{
+	int mantissa, exp;
+
+	if (thresh < 0 || thresh > MAX44009_MAXIMUM_THRESHOLD) {
+		return -EINVAL;
+	}
+
+	for (mantissa = thresh, exp = 0; mantissa > 0xff; exp++) {
+		mantissa >>= 1;
+	}
+
+	mantissa >>= 4;
+	mantissa &= 0xf;
+	exp <<= 4;
+
+	return exp | mantissa;
+}
+
+static int max44009_get_thr_reg(enum iio_event_direction dir)
+{
+	switch (dir) {
+	case IIO_EV_DIR_RISING:
+		return MAX44009_REG_UPPER_THR;
+	case IIO_EV_DIR_FALLING:
+		return MAX44009_REG_LOWER_THR;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int max44009_write_thresh(struct iio_dev *indio_dev,
+				 enum iio_event_direction dir, int val)
+{
+	struct max44009_data *data = iio_priv(indio_dev);
+	int thresh;
+	int reg;
+
+	reg = max44009_get_thr_reg(dir);
+	if (reg < 0) {
+		return reg;
+	}
+
+	thresh = max44009_thresh_byte_from_int(val);
+	if (thresh < 0) {
+		return thresh;
+	}
+
+	return max44009_write_reg(data, reg, thresh);
+}
+
+static int max44009_write_event_value(struct iio_dev *indio_dev,
+				      const struct iio_chan_spec *chan,
+				      enum iio_event_type type,
+				      enum iio_event_direction dir,
+				      enum iio_event_info info,
+				      int val, int val2)
+{
+	if (info != IIO_EV_INFO_VALUE || chan->type != IIO_LIGHT || val2 != 0) {
+		return -EINVAL;
+	}
+
+	return max44009_write_thresh(indio_dev, dir, val);
+}
+
+static int max44009_read_event_value(struct iio_dev *indio_dev,
+				     const struct iio_chan_spec *chan,
+				     enum iio_event_type type,
+				     enum iio_event_direction dir,
+				     enum iio_event_info info,
+				     int *val, int *val2)
+{
+	int thresh, reg;
+	struct max44009_data *data = iio_priv(indio_dev);
+
+	if (chan->type != IIO_LIGHT || type != IIO_EV_TYPE_THRESH) {
+		return -EINVAL;
+	}
+
+	reg = max44009_get_thr_reg(dir);
+	if (reg < 0) {
+		return reg;
+	}
+
+	thresh = max44009_read_reg(data, reg);
+	if (thresh < 0) {
+		return thresh;
+	}
+
+	*val = MAX44009_THRESHOLD(thresh);
+
+	return IIO_VAL_INT;
+}
+
+static int max44009_write_event_config(struct iio_dev *indio_dev,
+				       const struct iio_chan_spec *chan,
+				       enum iio_event_type type,
+				       enum iio_event_direction dir,
+				       int state)
+{
+	struct max44009_data *data = iio_priv(indio_dev);
+	int ret;
+
+	if (chan->type != IIO_LIGHT || type != IIO_EV_TYPE_THRESH) {
+		return -EINVAL;
+	}
+
+	ret = max44009_write_reg(data, MAX44009_REG_ENABLE, state);
+	if (ret < 0) {
+		return ret;
+	}
+
+	/*
+	 * Set device to trigger interrupt immediately upon exceeding
+	 * the threshold limit
+	 */
+	ret = max44009_write_reg(data, MAX44009_REG_THR_TIMER, 0);
+	if (ret < 0) {
+		return ret;
+	}
+
+	return 0;
+}
+
+static int max44009_read_event_config(struct iio_dev *indio_dev,
+				      const struct iio_chan_spec *chan,
+				      enum iio_event_type type,
+				      enum iio_event_direction dir)
+{
+	struct max44009_data *data = iio_priv(indio_dev);
+	int ret;
+
+	if (chan->type != IIO_LIGHT || type != IIO_EV_TYPE_THRESH) {
+		return -EINVAL;
+	}
+
+	ret = max44009_read_reg(data, MAX44009_REG_ENABLE);
+	if (ret < 0) {
+		return ret;
+	}
+
+	return ret;
+}
+
+static const struct iio_info max44009_info = {
+	.read_raw = max44009_read_raw,
+	.write_raw = max44009_write_raw,
+	.write_raw_get_fmt = max44009_write_raw_get_fmt,
+	.read_event_value = max44009_read_event_value,
+	.read_event_config = max44009_read_event_config,
+	.write_event_value = max44009_write_event_value,
+	.write_event_config = max44009_write_event_config,
+	.attrs = &max44009_attribute_group,
+};
+
+static int max44009_set_trigger_state(struct iio_trigger *trigger,
+				      bool enable)
+{
+	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trigger);
+	struct max44009_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = max44009_write_reg(data, MAX44009_REG_ENABLE, enable);
+	if (ret < 0) {
+		return ret;
+	}
+
+	ret = max44009_write_reg(data, MAX44009_REG_THR_TIMER, 0);
+	if (ret < 0) {
+		return ret;
+	}
+
+	return ret;
+}
+
+static const struct iio_trigger_ops max44009_trigger_ops = {
+	.set_trigger_state = max44009_set_trigger_state,
+};
+
+static irqreturn_t max44009_trigger_handler(int irq, void *p)
+{
+	struct iio_dev *indio_dev = p;
+	struct max44009_data *data = iio_priv(indio_dev);
+	int lux, upper, lower;
+	int ret;
+	enum iio_event_direction direction;
+
+	/* 32-bit for lux and 64-bit for timestamp */
+	u32 buf[3] = {0};
+
+	ret = max44009_read_reg(data, MAX44009_REG_STATUS);
+	if (ret <= 0) {
+		goto err;
+	}
+
+	ret = max44009_read_reg(data, MAX44009_REG_ENABLE);
+	if (ret <= 0) {
+		goto err;
+	}
+
+	/* Clear interrupt by disabling interrupt (see datasheet) */
+	ret = max44009_write_reg(data, MAX44009_REG_ENABLE, 0);
+	if (ret < 0) {
+		goto err;
+	}
+
+	lux = max44009_read_lux_raw(data);
+	if (lux < 0) {
+		goto err;
+	}
+
+	upper = max44009_read_reg(data, MAX44009_REG_UPPER_THR);
+	if (upper < 0) {
+		goto err;
+	}
+	upper = MAX44009_THRESHOLD(upper);
+
+	lower = max44009_read_reg(data, MAX44009_REG_LOWER_THR);
+	if (lower < 0) {
+		goto err;
+	}
+	lower = MAX44009_THRESHOLD(lower);
+
+	/* If lux is NOT out-of-bounds then the interrupt was not triggered
+	 * by this device
+	 */
+	if (lux < upper && lux > lower) {
+		goto err;
+	}
+
+	/* Get event for correct thresh direction */
+	if (lux >= upper) {
+		direction = IIO_EV_DIR_RISING;
+	} else if (lux <= lower) {
+		direction = IIO_EV_DIR_FALLING;
+	} else {
+		goto err;
+	}
+
+	buf[0] = lux;
+	iio_push_to_buffers_with_timestamp(indio_dev, &buf, data->timestamp);
+	iio_trigger_notify_done(data->trigger);
+
+	iio_push_event(indio_dev,
+		       IIO_UNMOD_EVENT_CODE(IIO_LIGHT, 0,
+					    IIO_EV_TYPE_THRESH, direction),
+		       data->timestamp);
+
+	ret = max44009_write_reg(data, MAX44009_REG_ENABLE, 1);
+	if (ret < 0) {
+		goto err;
+	}
+
+	return IRQ_HANDLED;
+
+err:
+	/* Re-enable interrupt */
+	max44009_write_reg(data, MAX44009_REG_ENABLE, 1);
+	return IRQ_NONE;
+}
+
+static irqreturn_t max44009_irq_handler(int irq, void *p)
+{
+	struct iio_dev *indio_dev = p;
+	struct max44009_data *data = iio_priv(indio_dev);
+
+	data->timestamp = iio_get_time_ns(indio_dev);
+	return IRQ_WAKE_THREAD;
+}
+
+static int max44009_probe(struct i2c_client *client,
+			  const struct i2c_device_id *id)
+{
+	struct max44009_data *data;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev) {
+		return -ENOMEM;
+	}
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->info = &max44009_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->name = MAX44009_DRV_NAME;
+	indio_dev->channels = max44009_channels;
+	indio_dev->num_channels = ARRAY_SIZE(max44009_channels);
+	mutex_init(&data->lock);
+
+	/* Clear stale interrupt bit */
+	ret = max44009_read_reg(data, MAX44009_REG_STATUS);
+	if (ret < 0) {
+		goto err;
+	}
+
+	if (client->irq > 0) {
+		ret = devm_request_threaded_irq(&client->dev, client->irq,
+						max44009_irq_handler,
+						max44009_trigger_handler,
+						IRQF_TRIGGER_FALLING |
+						IRQF_ONESHOT,
+						MAX44009_IRQ_NAME, indio_dev);
+		if (ret < 0) {
+			goto err;
+		}
+
+		ret = devm_iio_triggered_buffer_setup(&client->dev, indio_dev,
+						      max44009_irq_handler,
+						      max44009_trigger_handler,
+						      NULL);
+		if (ret < 0) {
+			goto err;
+		}
+
+		data->trigger = devm_iio_trigger_alloc(indio_dev->dev.parent,
+						       "%s-dev%d",
+						       indio_dev->name,
+						       indio_dev->id);
+		if (!data->trigger) {
+			ret = -ENOMEM;
+			goto err;
+		}
+		data->trigger->dev.parent = indio_dev->dev.parent;
+		data->trigger->ops = &max44009_trigger_ops;
+		iio_trigger_set_drvdata(data->trigger, indio_dev);
+
+		ret = devm_iio_trigger_register(&client->dev, data->trigger);
+		if (ret < 0) {
+			goto err;
+		}
+	}
+
+	ret = devm_iio_device_register(&client->dev, indio_dev);
+	if (ret < 0) {
+		goto err;
+	}
+
+	return 0;
+err:
+	mutex_destroy(&data->lock);
+	return ret;
+}
+
+static const struct i2c_device_id max44009_id[] = {
+	{ "max44009", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max44009_id);
+
+static struct i2c_driver max44009_driver = {
+	.driver = {
+		.name = MAX44009_DRV_NAME,
+	},
+	.probe = max44009_probe,
+	.id_table = max44009_id,
+};
+module_i2c_driver(max44009_driver);
+
+static const struct of_device_id max44009_of_match[] = {
+	{ .compatible = "maxim,max44009" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max44009_of_match);
+
+MODULE_AUTHOR("Robert Eshleman <bobbyeshleman@gmail.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_VERSION("1.0.0");
+MODULE_DESCRIPTION("MAX44009 ambient light sensor driver");
-- 
2.20.1