Message-ID: <30c4a0f9aff5a40879d6839ad8a5ce40565f0923.camel@analog.com>
Date:   Tue, 8 Oct 2019 06:52:50 +0000
From:   "Ardelean, Alexandru" <alexandru.Ardelean@...log.com>
To:     "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "Hennerich, Michael" <Michael.Hennerich@...log.com>,
        "manivannan.sadhasivam@...aro.org" <manivannan.sadhasivam@...aro.org>,
        "lars@...afoo.de" <lars@...afoo.de>,
        "jic23@...nel.org" <jic23@...nel.org>,
        "pmeerw@...erw.net" <pmeerw@...erw.net>,
        "knaack.h@....de" <knaack.h@....de>
CC:     "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>
Subject: Re: [PATCH 2/2] iio: light: Add support for ADUX1020 sensor

On Mon, 2019-10-07 at 15:40 +0530, Manivannan Sadhasivam wrote:
> [External]
> 

Hey,

Comments inline.

I thought I sent an initial review, but seems to have gotten lost [maybe in
my email client].
Oh well. I managed to re-do it anyway.

I tried to group them this time.

The more prominent part is [3]; this driver needs a bit more error checking
on regmap_() returns.

Generally some notes:
- Is there a need to implement the 32Khz or 32Mhz clock calibration
routines on startup? Some drivers need this, some don't/
- From the functional diagram, it looks like maybe the VREF would be needed
to be hooked via a regulator framework; but this could be done later
- Just curios here: there is gesture mode as well; will that be implemented
later? Or will there be other modes implemented?

If I remember anything else I may come back with a reply.

Thanks
Alex

> Add initial support for Analog Devices ADUX1020 Photometric sensor.
> Only proximity mode has been enabled for now.
> 
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---
>  drivers/iio/light/Kconfig    |  11 +
>  drivers/iio/light/Makefile   |   1 +
>  drivers/iio/light/adux1020.c | 783 +++++++++++++++++++++++++++++++++++

Does MAINTAINERS need updating as well?

>  3 files changed, 795 insertions(+)
>  create mode 100644 drivers/iio/light/adux1020.c
> 
> diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
> index 08d7e1ef2186..3f8c8689cd89 100644
> --- a/drivers/iio/light/Kconfig
> +++ b/drivers/iio/light/Kconfig
> @@ -32,6 +32,17 @@ config ADJD_S311
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called adjd_s311.
>  
> +config ADUX1020
> +	tristate "ADUX1020 photometric sensor"
> +	select REGMAP_I2C
> +	depends on I2C
> +	help
> +	 Say Y here if you want to build a driver for the Analog Devices
> +	 ADUX1020 photometric sensor.
> +
> +	 To compile this driver as a module, choose M here: the
> +	 module will be called adux1020.
> +
>  config AL3320A
>  	tristate "AL3320A ambient light sensor"
>  	depends on I2C
> diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
> index 00d1f9b98f39..5d650ce46a40 100644
> --- a/drivers/iio/light/Makefile
> +++ b/drivers/iio/light/Makefile
> @@ -6,6 +6,7 @@
>  # When adding new entries keep the list in alphabetical order
>  obj-$(CONFIG_ACPI_ALS)		+= acpi-als.o
>  obj-$(CONFIG_ADJD_S311)		+= adjd_s311.o
> +obj-$(CONFIG_ADUX1020)		+= adux1020.o
>  obj-$(CONFIG_AL3320A)		+= al3320a.o
>  obj-$(CONFIG_APDS9300)		+= apds9300.o
>  obj-$(CONFIG_APDS9960)		+= apds9960.o
> diff --git a/drivers/iio/light/adux1020.c b/drivers/iio/light/adux1020.c
> new file mode 100644
> index 000000000000..d0b76e5b44f1
> --- /dev/null
> +++ b/drivers/iio/light/adux1020.c
> @@ -0,0 +1,783 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * adux1020.c - Support for Analog Devices ADUX1020 photometric sensor

Maybe drop the adux1020.c part?
I think something like this should be sufficient:
"Analog Devices ADUX1020 photometric sensor"

> + *
> + * Copyright (C) 2019 Linaro Ltd.
> + * Author: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> + *
> + * TODO: Triggered buffer support

Maybe drop the TODO?
It's not needed for mainline.

> + */
> +
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/regmap.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/iio/events.h>
> +
> +#define ADUX1020_REGMAP_NAME		"adux1020_regmap"
> +#define ADUX1020_DRV_NAME		"adux1020"
> +
> +/* System registers */
> +#define ADUX1020_REG_CHIP_ID		0x08
> +#define ADUX1020_REG_SLAVE_ADDRESS	0x09
> +
> +#define ADUX1020_REG_SW_RESET		0x0f
> +#define ADUX1020_REG_INT_ENABLE		0x1c
> +#define ADUX1020_REG_INT_POLARITY	0x1d
> +#define ADUX1020_REG_PROX_TH_ON1	0x2a
> +#define ADUX1020_REG_PROX_TH_OFF1	0x2b
> +#define	ADUX1020_REG_PROX_TYPE		0x2f
> +#define	ADUX1020_REG_TEST_MODES_3	0x32
> +#define	ADUX1020_REG_FORCE_MODE		0x33
> +#define	ADUX1020_REG_FREQUENCY		0x40
> +#define ADUX1020_REG_LED_CURRENT	0x41
> +#define	ADUX1020_REG_OP_MODE		0x45
> +#define	ADUX1020_REG_INT_MASK		0x48
> +#define	ADUX1020_REG_INT_STATUS		0x49
> +#define	ADUX1020_REG_DATA_BUFFER	0x60
> +
> +/* Chip ID bits */
> +#define ADUX1020_CHIP_ID_MASK		GENMASK(11, 0)
> +#define ADUX1020_CHIP_ID		0x03fc
> +
> +#define ADUX1020_MODE_OUT_SHIFT		4

I'm seeing a few _SHIFT macros.
Maybe use the FIELD_PREP() macro where possible? [1]

> +#define ADUX1020_MODE_OUT_PROX_I	1
> +#define ADUX1020_MODE_OUT_PROX_XY	3
> +
> +#define ADUX1020_SW_RESET		BIT(1)
> +#define ADUX1020_FIFO_FLUSH		BIT(15)
> +#define ADUX1020_OP_MODE_MASK		GENMASK(3, 0)
> +#define ADUX1020_DATA_OUT_MODE_MASK	GENMASK(7, 4)
> +
> +#define ADUX1020_MODE_INT_MASK		GENMASK(7, 0)
> +#define ADUX1020_INT_ENABLE		0x2096
> +#define ADUX1020_INT_DISABLE		0x2090
> +#define ADUX1020_PROX_INT_ENABLE	0x00f0
> +#define ADUX1020_PROX_ON1_INT		BIT(0)
> +#define ADUX1020_PROX_OFF1_INT		BIT(1)
> +#define ADUX1020_FIFO_INT_ENABLE	0x7f
> +#define ADUX1020_MODE_INT_DISABLE	0xff
> +#define ADUX1020_MODE_INT_STATUS_MASK	GENMASK(7, 0)
> +#define ADUX1020_FIFO_STATUS_MASK	GENMASK(15, 8)
> +#define ADUX1020_PROX_TYPE		BIT(15)
> +
> +#define ADUX1020_INT_PROX_ON1		BIT(0)
> +#define ADUX1020_INT_PROX_OFF1		BIT(1)
> +
> +#define	ADUX1020_FORCE_CLOCK_ON		0x0f4f
> +#define	ADUX1020_FORCE_CLOCK_RESET	0x0040

nitpick: indentation seems inconsistent here

> +#define ADUX1020_ACTIVE_4_STATE		0x0008
> +
> +#define ADUX1020_PROX_FREQ_MASK		GENMASK(7, 4)
> +#define ADUX1020_PROX_FREQ_SHIFT	4

Same as [1]. Maybe use FIELD_PREP() together with ADUX1020_PROX_FREQ_MASK?
See other examples, but we sometimes use them as:

#define ADUX_PROX_FREQ_SET(x)    FIELD_PREP(ADUX1020_PROX_FREQ_MASK, (x))

> +
> +#define ADUX1020_LED_CURRENT_MASK	GENMASK(3, 0)
> +#define ADUX1020_LED_PIREF_EN		BIT(12)
> +
> +/* Operating modes */
> +enum adux1020_op_modes {
> +	ADUX1020_MODE_STANDBY,
> +	ADUX1020_MODE_PROX_I,
> +	ADUX1020_MODE_PROX_XY,
> +	ADUX1020_MODE_GEST,
> +	ADUX1020_MODE_SAMPLE,
> +	ADUX1020_MODE_FORCE = 0x0e,
> +	ADUX1020_MODE_IDLE = 0x0f,
> +};
> +
> +struct adux1020_data {
> +	struct i2c_client *client;
> +	struct iio_dev *indio_dev;
> +	struct mutex lock;
> +	struct regmap *regmap;
> +};
> +
> +struct adux1020_mode_data {
> +	u8 bytes;
> +	u8 buf_len;
> +	u16 int_en;
> +};
> +
> +static const struct adux1020_mode_data adux1020_modes[] = {
> +	[ADUX1020_MODE_PROX_I] = {
> +		.bytes = 2,
> +		.buf_len = 1,
> +		.int_en = ADUX1020_PROX_INT_ENABLE,
> +	},
> +};
> +
> +static const struct regmap_config adux1020_regmap_config = {
> +	.name = ADUX1020_REGMAP_NAME,
> +	.reg_bits = 8,
> +	.val_bits = 16,
> +	.max_register = 0x6F,
> +	.cache_type = REGCACHE_NONE,
> +};
> +
> +static const int adux1020_def_conf[][2] = {

Maybe use "struct reg_sequence" here?[2]
You could then use "regmap_multi_reg_write()"

> +	{ 0x000c, 0x000f },
> +	{ 0x0010, 0x1010 },
> +	{ 0x0011, 0x004c },
> +	{ 0x0012, 0x5f0c },
> +	{ 0x0013, 0xada5 },
> +	{ 0x0014, 0x0080 },
> +	{ 0x0015, 0x0000 },
> +	{ 0x0016, 0x0600 },
> +	{ 0x0017, 0x0000 },
> +	{ 0x0018, 0x2693 },
> +	{ 0x0019, 0x0004 },
> +	{ 0x001a, 0x4280 },
> +	{ 0x001b, 0x0060 },
> +	{ 0x001c, 0x2094 },
> +	{ 0x001d, 0x0020 },
> +	{ 0x001e, 0x0001 },
> +	{ 0x001f, 0x0100 },
> +	{ 0x0020, 0x0320 },
> +	{ 0x0021, 0x0A13 },
> +	{ 0x0022, 0x0320 },
> +	{ 0x0023, 0x0113 },
> +	{ 0x0024, 0x0000 },
> +	{ 0x0025, 0x2412 },
> +	{ 0x0026, 0x2412 },
> +	{ 0x0027, 0x0022 },
> +	{ 0x0028, 0x0000 },
> +	{ 0x0029, 0x0300 },
> +	{ 0x002a, 0x0700 },
> +	{ 0x002b, 0x0600 },
> +	{ 0x002c, 0x6000 },
> +	{ 0x002d, 0x4000 },
> +	{ 0x002e, 0x0000 },
> +	{ 0x002f, 0x0000 },
> +	{ 0x0030, 0x0000 },
> +	{ 0x0031, 0x0000 },
> +	{ 0x0032, 0x0040 },
> +	{ 0x0033, 0x0008 },
> +	{ 0x0034, 0xE400 },
> +	{ 0x0038, 0x8080 },
> +	{ 0x0039, 0x8080 },
> +	{ 0x003a, 0x2000 },
> +	{ 0x003b, 0x1f00 },
> +	{ 0x003c, 0x2000 },
> +	{ 0x003d, 0x2000 },
> +	{ 0x003e, 0x0000 },
> +	{ 0x0040, 0x8069 },
> +	{ 0x0041, 0x1f2f },
> +	{ 0x0042, 0x4000 },
> +	{ 0x0043, 0x0000 },
> +	{ 0x0044, 0x0008 },
> +	{ 0x0046, 0x0000 },
> +	{ 0x0048, 0x00ef },
> +	{ 0x0049, 0x0000 },
> +	{ 0x0045, 0x0000 },
> +};
> +
> +static const int adux1020_rate[][2] = {
> +	{ 0, 100000 },
> +	{ 0, 200000 },
> +	{ 0, 500000 },
> +	{ 1, 0 },
> +	{ 2, 0 },
> +	{ 5, 0 },
> +	{ 10, 0 },
> +	{ 20, 0 },
> +	{ 50, 0 },
> +	{ 100, 0 },
> +	{ 190, 0 },
> +	{ 450, 0 },
> +	{ 820, 0 },
> +	{ 1400, 0 },
> +};
> +
> +static const int adux1020_led_current[][2] = {
> +	{ 0, 25000 },
> +	{ 0, 40000 },
> +	{ 0, 55000 },
> +	{ 0, 70000 },
> +	{ 0, 85000 },
> +	{ 0, 100000 },
> +	{ 0, 115000 },
> +	{ 0, 130000 },
> +	{ 0, 145000 },
> +	{ 0, 160000 },
> +	{ 0, 175000 },
> +	{ 0, 190000 },
> +	{ 0, 205000 },
> +	{ 0, 220000 },
> +	{ 0, 235000 },
> +	{ 0, 250000 },
> +};
> +
> +static void adux1020_flush_fifo(struct adux1020_data *data)
> +{
> +	/* Force Idle mode */
> +	regmap_write(data->regmap, ADUX1020_REG_FORCE_MODE,
> +		     ADUX1020_ACTIVE_4_STATE);
> +	regmap_update_bits(data->regmap, ADUX1020_REG_OP_MODE,
> +			   ADUX1020_OP_MODE_MASK, ADUX1020_MODE_FORCE);
> +	regmap_update_bits(data->regmap, ADUX1020_REG_OP_MODE,
> +			   ADUX1020_OP_MODE_MASK, ADUX1020_MODE_IDLE);
> +
> +	/* Flush FIFO */
> +	regmap_write(data->regmap, ADUX1020_REG_TEST_MODES_3,
> +		     ADUX1020_FORCE_CLOCK_ON);
> +	regmap_write(data->regmap, ADUX1020_REG_INT_STATUS,
> +		     ADUX1020_FIFO_FLUSH);
> +	regmap_write(data->regmap, ADUX1020_REG_TEST_MODES_3,
> +		     ADUX1020_FORCE_CLOCK_RESET);

These bits could use with some minimal error checking.[3]
Maybe also convert to return int and check errors.

> +}
> +
> +static int adux1020_read_fifo(struct adux1020_data *data, u16 *buf, u8
> buf_len)
> +{
> +	int i, ret = -EINVAL;
> +	unsigned int regval;
> +
> +	/* Enable 32MHz clock */
> +	regmap_write(data->regmap, ADUX1020_REG_TEST_MODES_3,
> +		     ADUX1020_FORCE_CLOCK_ON);

This looks weird [the FORCE_CLOCK_ON], but it is what the datasheet says.
Also, related to [3]: some error checking this return would be useful.

> +
> +	for (i = 0; i < buf_len; i++) {
> +		ret = regmap_read(data->regmap, ADUX1020_REG_DATA_BUFFER,
> +				      &regval);
> +		if (ret < 0)
> +			goto err_out;
> +
> +		buf[i] = regval;
> +	}
> +
> +	/* Set 32MHz clock to be controlled by internal state machine */
> +	regmap_write(data->regmap, ADUX1020_REG_TEST_MODES_3,
> +		     ADUX1020_FORCE_CLOCK_RESET);
> +
> +err_out:
> +	return ret;
> +}
> +
> +static void adux1020_set_mode(struct adux1020_data *data,
> +			      enum adux1020_op_modes mode)
> +{
> +	/* Switch to standby mode before changing the mode */
> +	regmap_write(data->regmap, ADUX1020_REG_OP_MODE,
> ADUX1020_MODE_STANDBY);

[3] error checking maybe? and maybe int return?

> +
> +	/* Set data out and switch to the desired mode */
> +	if (mode == ADUX1020_MODE_PROX_I) {

This could become a switch() statement, so that when/if other modes get
added, the patch looks cleaner.

> +		regmap_update_bits(data->regmap, ADUX1020_REG_OP_MODE,
> +			ADUX1020_DATA_OUT_MODE_MASK,
> +			ADUX1020_MODE_OUT_PROX_I <<
> ADUX1020_MODE_OUT_SHIFT);

Related to [1]: a FIELD_PREP() macro would be useful.

> +		regmap_update_bits(data->regmap, ADUX1020_REG_OP_MODE,
> +			ADUX1020_OP_MODE_MASK, ADUX1020_MODE_PROX_I);
> +	}
> +}
> +
> +static int adux1020_measure(struct adux1020_data *data,
> +			    enum adux1020_op_modes mode,
> +			    u16 *val)
> +{
> +	int ret, tries = 50;
> +	unsigned int status;
> +
> +	mutex_lock(&data->lock);

The scope of this lock looks like it would need to be extended a bit.
See [4] on some more notes for this.

> +
> +	/* Disable INT pin as polling is going to be used */
> +	regmap_write(data->regmap, ADUX1020_REG_INT_ENABLE,
> +		     ADUX1020_INT_DISABLE);
> +
> +	/* Enable mode interrupt */
> +	regmap_update_bits(data->regmap, ADUX1020_REG_INT_MASK,
> +			   ADUX1020_MODE_INT_MASK,
> +			   adux1020_modes[mode].int_en);

[3] maybe some more error checking?

> +
> +	while (tries--) {
> +		ret = regmap_read(data->regmap, ADUX1020_REG_INT_STATUS,
> +				  &status);
> +		if (ret < 0)
> +			goto fail;
> +
> +		status &= ADUX1020_FIFO_STATUS_MASK;
> +		if (status >= adux1020_modes[mode].bytes)
> +			break;
> +		msleep(20);
> +	}
> +
> +	if (tries < 0) {
> +		ret = -EIO;
> +		goto fail;
> +	}
> +

Regarding [8], the buffer is passed from adux1020_read_raw(), so maybe just
move the buffer here, since the information about size is near the buffer
definition.
Then do *val = buf[0];

> +	ret = adux1020_read_fifo(data, val, adux1020_modes[mode].buf_len);
> +	if (ret < 0)
> +		goto fail;
> +
> +	/* Clear mode interrupt */
> +	regmap_write(data->regmap, ADUX1020_REG_INT_STATUS,
> +			   (~adux1020_modes[mode].int_en));
> +	/* Disable mode interrupts */
> +	regmap_update_bits(data->regmap, ADUX1020_REG_INT_MASK,
> +			   ADUX1020_MODE_INT_MASK,
> ADUX1020_MODE_INT_DISABLE);
> +
> +fail:
> +	mutex_unlock(&data->lock);
> +
> +	return ret;
> +}
> +
> +static int adux1020_read_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     int *val, int *val2, long mask)
> +{
> +	struct adux1020_data *data = iio_priv(indio_dev);
> +	u16 buf[3];

This buffer looks a bit weird. [8]
It's 3 elements-wide and passed without any information about size.
And only the first element is used.
So, maybe just convert u16 buf[3] -> u16 buf?

> +	int ret = -EINVAL;
> +	unsigned int regval;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		switch (chan->type) {
> +		case IIO_PROXIMITY:
> +			adux1020_set_mode(data, ADUX1020_MODE_PROX_I);
> +			ret = adux1020_measure(data, ADUX1020_MODE_PROX_I,
> buf);

Regarding [4]: I'm thinking that the lock could be extended to
adux1020_{read,write}_raw() & adux1020_{read,write}_event_config()
functions, especialy [or only in places] where functions seem to do
consecutive R/W ops.

> +			if (ret < 0)
> +				return ret;
> +
> +			*val = buf[0];
> +			ret = IIO_VAL_INT;
> +			break;
> +		default:
> +			break;
> +		}
> +		break;
> +	case IIO_CHAN_INFO_PROCESSED:
> +		switch (chan->type) {
> +		case IIO_CURRENT:
> +			ret = regmap_read(data->regmap,
> +					  ADUX1020_REG_LED_CURRENT,
> &regval);
> +			if (ret < 0)
> +				return ret;
> +
> +			regval = regval & ADUX1020_LED_CURRENT_MASK;
> +
> +			*val = adux1020_led_current[regval][0];
> +			*val2 = adux1020_led_current[regval][1];
> +
> +			ret = IIO_VAL_INT_PLUS_MICRO;
> +			break;
> +		default:
> +			break;
> +		}
> +		break;
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		switch (chan->type) {
> +		case IIO_PROXIMITY:
> +			ret = regmap_read(data->regmap,
> ADUX1020_REG_FREQUENCY,
> +					  &regval);
> +			if (ret < 0)
> +				return ret;
> +
> +			regval = (regval & ADUX1020_PROX_FREQ_MASK) >>
> +				  ADUX1020_PROX_FREQ_SHIFT;

Related to [1]: a FIELD_PREP() macro would be useful.

> +
> +			*val = adux1020_rate[regval][0];
> +			*val2 = adux1020_rate[regval][1];
> +
> +			ret = IIO_VAL_INT_PLUS_MICRO;
> +			break;
> +		default:
> +			break;
> +		}
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	return ret;
> +};
> +
> +static int adux1020_write_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     int val, int val2, long mask)
> +{
> +	struct adux1020_data *data = iio_priv(indio_dev);
> +	int i, ret = -EINVAL;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		if (chan->type == IIO_PROXIMITY) {
> +			for (i = 0; i < ARRAY_SIZE(adux1020_rate); i++) {
> +				if ((val == adux1020_rate[i][0]) &&
> +				     (val2 == adux1020_rate[i][1])) {
> +					ret = regmap_update_bits(data-
> >regmap,
> +						ADUX1020_REG_FREQUENCY,
> +						ADUX1020_PROX_FREQ_MASK,
> +						i <<
> ADUX1020_PROX_FREQ_SHIFT);
> +				}
> +			}

[5] This looks as it has too many level of indentations.
And could be reworked with either using the "find_closest()" macro, or at
least split into a helper that finds the index in the "adux1020_rate" array
based on val & val2.

Then you get something like:
------------------------------------------------------------
i = adux1020_find_index(adux1020_rate, val, val2);
if (i < 0)
    return i;

return regmap_update_bits(data->regmap,
                          ADUX1020_REG_FREQUENCY,
                          ADUX1020_PROX_FREQ_SET(i));
------------------------------------------------------------

> +		}
> +		break;
> +	case IIO_CHAN_INFO_PROCESSED:
> +		if (chan->type == IIO_CURRENT) {
> +			for (i = 0; i < ARRAY_SIZE(adux1020_led_current);
> i++) {
> +				if ((val == adux1020_led_current[i][0]) &&
> +				     (val2 == adux1020_led_current[i][1]))
> {
> +					ret = regmap_update_bits(data-
> >regmap,
> +						ADUX1020_REG_LED_CURRENT,
> +						ADUX1020_LED_CURRENT_MASK,
> i);
> +				}
> +			}

Same comment as [5]

> +		}
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
> +static int adux1020_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 adux1020_data *data = iio_priv(indio_dev);
> +
> +	regmap_write(data->regmap, ADUX1020_REG_INT_ENABLE,
> +		     ADUX1020_INT_ENABLE);
> +

Regarding [4]: it looks like the lock could be useful here.
Regarding [3]: more error checking could be useful.


> +	regmap_write(data->regmap, ADUX1020_REG_INT_POLARITY, 0);
> +
> +	switch (chan->type) {
> +	case IIO_PROXIMITY:
> +		if (dir == IIO_EV_DIR_RISING) {
> +			regmap_update_bits(data->regmap,
> ADUX1020_REG_INT_MASK,
> +					   ADUX1020_PROX_ON1_INT,
> +					   state ? 0 :
> ADUX1020_PROX_ON1_INT);
> +		} else {
> +			regmap_update_bits(data->regmap,
> ADUX1020_REG_INT_MASK,
> +					   ADUX1020_PROX_OFF1_INT,
> +					   state ? 0 :
> ADUX1020_PROX_OFF1_INT);
> +		}

[6] More about style/preference.
I like the part in adux1020_read_event_config(), where

-------------------------------------------------
  if (dir == IIO_EV_DIR_RISING)
      mask = ADUX1020_PROX_ON1_INT;
  else
      mask = ADUX1020_PROX_OFF1_INT;
-------------------------------------------------

Then this could become:

-------------------------------------------------
if (state)
    state = mask;
else
    state = 0;

ret = regmap_update_bits(data->regmap,
                         ADUX1020_REG_INT_MASK,
                         mask, state);
-------------------------------------------------


> +
> +		/*
> +		 * Trigger proximity interrupt when the intensity is above
> +		 * or below threshold
> +		 */
> +		regmap_update_bits(data->regmap, ADUX1020_REG_PROX_TYPE,
> +				   ADUX1020_PROX_TYPE, ADUX1020_PROX_TYPE);
> +
> +		/* Set proximity mode */
> +		adux1020_set_mode(data, ADUX1020_MODE_PROX_I);
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static int adux1020_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 adux1020_data *data = iio_priv(indio_dev);
> +	int ret, mask;
> +	unsigned int regval;
> +
> +	switch (chan->type) {
> +	case IIO_PROXIMITY:
> +		if (dir == IIO_EV_DIR_RISING)
> +			mask = ADUX1020_PROX_ON1_INT;
> +		else
> +			mask = ADUX1020_PROX_OFF1_INT;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	ret = regmap_read(data->regmap, ADUX1020_REG_INT_MASK, &regval);
> +	if (ret < 0)
> +		return ret;
> +
> +	return !(regval & mask);
> +}
> +
> +static int adux1020_read_thresh(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)
> +{
> +	struct adux1020_data *data = iio_priv(indio_dev);
> +	u8 reg;
> +	int ret;
> +	unsigned int regval;
> +
> +	switch (chan->type) {
> +	case IIO_PROXIMITY:
> +		if (dir == IIO_EV_DIR_RISING)
> +			reg = ADUX1020_REG_PROX_TH_ON1;
> +		else
> +			reg = ADUX1020_REG_PROX_TH_OFF1;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	ret = regmap_read(data->regmap, reg, &regval);
> +	if (ret < 0)
> +		return ret;
> +
> +	*val = regval;
> +
> +	return IIO_VAL_INT;
> +}
> +
> +static int adux1020_write_thresh(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)
> +{
> +	struct adux1020_data *data = iio_priv(indio_dev);
> +	u8 reg;
> +
> +	switch (chan->type) {
> +	case IIO_PROXIMITY:
> +		if (dir == IIO_EV_DIR_RISING)
> +			reg = ADUX1020_REG_PROX_TH_ON1;
> +		else
> +			reg = ADUX1020_REG_PROX_TH_OFF1;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	/* Full scale threshold value is 0-65535  */
> +	if (val < 0 || val > 65535)
> +		return -EINVAL;
> +
> +	return regmap_write(data->regmap, reg, val);
> +}
> +
> +static const struct iio_event_spec adux1020_proximity_event[] = {
> +	{
> +		.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 adux1020_channels[] = {
> +	{
> +		.type = IIO_PROXIMITY,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_SAMP_FREQ),
> +		.event_spec = adux1020_proximity_event,
> +		.num_event_specs = ARRAY_SIZE(adux1020_proximity_event),
> +	},
> +	{
> +		.type = IIO_CURRENT,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> +		.extend_name = "led",
> +	},
> +};
> +
> +static IIO_CONST_ATTR(sampling_frequency_available,
> +		      "0.1 0.2 0.5 1 2 5 10 20 50 100 190 450 820 1400");

This could re-use the IIO_CONST_ATTR_SAMP_FREQ_AVAIL() macro.

> +
> +static struct attribute *adux1020_attributes[] = {
> +	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group adux1020_attribute_group = {
> +	.attrs = adux1020_attributes,
> +};
> +
> +static const struct iio_info adux1020_info = {
> +	.attrs = &adux1020_attribute_group,
> +	.read_raw = adux1020_read_raw,
> +	.write_raw = adux1020_write_raw,
> +	.read_event_config = adux1020_read_event_config,
> +	.write_event_config = adux1020_write_event_config,
> +	.read_event_value = adux1020_read_thresh,
> +	.write_event_value = adux1020_write_thresh,
> +};
> +
> +static irqreturn_t adux1020_interrupt_handler(int irq, void *private)
> +{
> +	struct iio_dev *indio_dev = private;
> +	struct adux1020_data *data = iio_priv(indio_dev);
> +	int ret, status;
> +
> +	ret = regmap_read(data->regmap, ADUX1020_REG_INT_STATUS, &status);
> +	if (ret < 0)
> +		return ret;
> +
> +	status &= ADUX1020_MODE_INT_STATUS_MASK;
> +
> +	if (status & ADUX1020_INT_PROX_ON1) {
> +		iio_push_event(indio_dev,
> +				IIO_UNMOD_EVENT_CODE(IIO_PROXIMITY, 0,
> +					IIO_EV_TYPE_THRESH,
> +					IIO_EV_DIR_RISING),
> +				iio_get_time_ns(indio_dev));
> +	}
> +
> +	if (status & ADUX1020_INT_PROX_OFF1) {
> +		iio_push_event(indio_dev,
> +				IIO_UNMOD_EVENT_CODE(IIO_PROXIMITY, 0,
> +					IIO_EV_TYPE_THRESH,
> +					IIO_EV_DIR_FALLING),
> +				iio_get_time_ns(indio_dev));
> +	}
> +
> +	regmap_update_bits(data->regmap, ADUX1020_REG_INT_STATUS,
> +			   ADUX1020_MODE_INT_MASK, status);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int adux1020_chip_init(struct adux1020_data *data)
> +{
> +	struct i2c_client *client = data->client;
> +	int ret, i;
> +	unsigned int val;
> +
> +	ret = regmap_read(data->regmap, ADUX1020_REG_CHIP_ID, &val);
> +	if (ret < 0)
> +		return ret;
> +
> +	val &= ADUX1020_CHIP_ID_MASK;
> +
> +	if (val != ADUX1020_CHIP_ID) {
> +		dev_err(&client->dev, "invalid chip id 0x%04x\n", val);
> +		return -ENODEV;
> +	};
> +
> +	dev_dbg(&client->dev, "Detected ADUX1020 with chip id: 0x%04x\n",
> val);
> +
> +	/* Perform software reset */
> +	regmap_update_bits(data->regmap, ADUX1020_REG_SW_RESET,
> +			   ADUX1020_SW_RESET, ADUX1020_SW_RESET);
> +
> +	/* Load default configuration */
> +	for (i = 0; i < ARRAY_SIZE(adux1020_def_conf); i++)
> +		regmap_write(data->regmap, adux1020_def_conf[i][0],
> +			     adux1020_def_conf[i][1]);
> +
> +	adux1020_flush_fifo(data);
> +
> +	/* Use LED_IREF for proximity mode */
> +	regmap_update_bits(data->regmap, ADUX1020_REG_LED_CURRENT,
> +			   ADUX1020_LED_PIREF_EN, 0);
> +
> +	/* Mask all interrupts */
> +	regmap_update_bits(data->regmap, ADUX1020_REG_INT_MASK,
> +			   ADUX1020_MODE_INT_MASK,
> ADUX1020_MODE_INT_DISABLE);

Same as [3]: a bit more error checking here could be useful.

> +
> +	return 0;
> +}
> +
> +static int adux1020_probe(struct i2c_client *client,
> +			  const struct i2c_device_id *id)
> +{
> +	struct adux1020_data *data;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->info = &adux1020_info;
> +	indio_dev->name = ADUX1020_DRV_NAME;
> +	indio_dev->channels = adux1020_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(adux1020_channels);
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	data = iio_priv(indio_dev);
> +	i2c_set_clientdata(client, indio_dev);
> +
> +	data->regmap = devm_regmap_init_i2c(client,
> &adux1020_regmap_config);
> +	if (IS_ERR(data->regmap)) {
> +		dev_err(&client->dev, "regmap initialization failed.\n");
> +		return PTR_ERR(data->regmap);
> +	}
> +
> +	data->client = client;
> +	data->indio_dev = indio_dev;
> +	mutex_init(&data->lock);
> +
> +	ret = adux1020_chip_init(data);
> +	if (ret)
> +		goto err_out;
> +
> +	if (client->irq) {
> +		ret = devm_request_threaded_irq(&client->dev, client->irq,
> +				NULL, adux1020_interrupt_handler,
> +				IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
> +				ADUX1020_DRV_NAME, indio_dev);
> +		if (ret) {
> +			dev_err(&client->dev, "irq request error %d\n",
> -ret);
> +			goto err_out;
> +		}
> +	}
> +
> +	ret = iio_device_register(indio_dev);

[7] Jonathan may correct me here.
If this doesn't need to do anything more later, this could use
devm_iio_device_register(), and then the  adux1020_remove() hook could be
removed.

> +	if (ret) {
> +		dev_err(&client->dev, "Failed to register IIO device\n");
> +		goto err_out;
> +	}
> +
> +	return 0;
> +
> +err_out:
> +	return ret;
> +}
> +
> +static int adux1020_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +
> +	iio_device_unregister(indio_dev);
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id adux1020_id[] = {
> +	{ "adux1020", 0 },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, adux1020_id);
> +
> +static const struct of_device_id adux1020_of_match[] = {
> +	{ .compatible = "adi,adux1020" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, adux1020_of_match);
> +
> +static struct i2c_driver adux1020_driver = {
> +	.driver = {
> +		.name	= ADUX1020_DRV_NAME,
> +		.of_match_table = adux1020_of_match,
> +	},
> +	.probe		= adux1020_probe,
> +	.remove		= adux1020_remove,
> +	.id_table	= adux1020_id,
> +};
> +module_i2c_driver(adux1020_driver);
> +
> +MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>"
> );
> +MODULE_DESCRIPTION("ADUX1020 photometric sensor");
> +MODULE_LICENSE("GPL");

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