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Date:   Mon, 21 Jan 2019 19:18:04 -0600
From:   Rob Herring <robh@...nel.org>
To:     Robert Eshleman <bobbyeshleman@...il.com>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Mark Rutland <mark.rutland@....com>, linux-iio@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: light: add driver support for MAX44009

On Wed, Jan 16, 2019 at 10:56:23PM -0800, Robert Eshleman wrote:
> 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@...il.com>
> ---
>  .../bindings/iio/light/max44009.txt           |  25 +

Please split bindings to a separate patch.

>  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@...il.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@...il.com>");
> +MODULE_LICENSE("GPL v2");
> +MODULE_VERSION("1.0.0");
> +MODULE_DESCRIPTION("MAX44009 ambient light sensor driver");
> -- 
> 2.20.1
> 

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