Date:   Fri, 25 Mar 2022 13:25:14 +0100
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Shreeya Patel <shreeya.patel@...labora.com>, jic23@...nel.org,
        lars@...afoo.de, robh+dt@...nel.org, Zhigang.Shi@...eon.com,
        krisman@...labora.com
Cc:     linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel@...labora.com,
        alvaro.soliverez@...labora.com
Subject: Re: [PATCH 3/3] iio: light: Add support for ltrf216a sensor

On 25/03/2022 11:30, Shreeya Patel wrote:
> From: Zhigang Shi <Zhigang.Shi@...eon.com>
> 
> Add initial support for ltrf216a ambient light sensor.
> 
> Datasheet :-
> https://gitlab.steamos.cloud/shreeya/iio/-/blob/main/LTR-F216A-QT.pdf
> 
> 
> Co-developed-by: Shreeya Patel <shreeya.patel@...labora.com>
> Signed-off-by: Shreeya Patel <shreeya.patel@...labora.com>
> Signed-off-by: Zhigang Shi <Zhigang.Shi@...eon.com>
> ---
>  drivers/iio/light/Kconfig    |  10 ++
>  drivers/iio/light/Makefile   |   1 +
>  drivers/iio/light/ltrf216a.c | 334 +++++++++++++++++++++++++++++++++++
>  3 files changed, 345 insertions(+)
>  create mode 100644 drivers/iio/light/ltrf216a.c
> 
> diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
> index a62c7b4b8678..08fa383a8ca7 100644
> --- a/drivers/iio/light/Kconfig
> +++ b/drivers/iio/light/Kconfig
> @@ -318,6 +318,16 @@ config SENSORS_LM3533
>  	  changes. The ALS-control output values can be set per zone for the
>  	  three current output channels.
>  
> +config LTRF216A
> +        tristate "Liteon LTRF216A Light Sensor"
> +        depends on I2C
> +        help
> +          If you say Y or M here, you get support for Liteon LTRF216A
> +          Ambient Light Sensor.
> +
> +          If built as a dynamically linked module, it will be called
> +          ltrf216a.
> +
>  config LTR501
>  	tristate "LTR-501ALS-01 light sensor"
>  	depends on I2C
> diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
> index d10912faf964..8fa91b9fe5b6 100644
> --- a/drivers/iio/light/Makefile
> +++ b/drivers/iio/light/Makefile
> @@ -30,6 +30,7 @@ obj-$(CONFIG_SENSORS_ISL29028)	+= isl29028.o
>  obj-$(CONFIG_ISL29125)		+= isl29125.o
>  obj-$(CONFIG_JSA1212)		+= jsa1212.o
>  obj-$(CONFIG_SENSORS_LM3533)	+= lm3533-als.o
> +obj-$(CONFIG_LTRF216A)		+= ltrf216a.o
>  obj-$(CONFIG_LTR501)		+= ltr501.o
>  obj-$(CONFIG_LV0104CS)		+= lv0104cs.o
>  obj-$(CONFIG_MAX44000)		+= max44000.o
> diff --git a/drivers/iio/light/ltrf216a.c b/drivers/iio/light/ltrf216a.c
> new file mode 100644
> index 000000000000..99295358a7fe
> --- /dev/null
> +++ b/drivers/iio/light/ltrf216a.c
> @@ -0,0 +1,334 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * LTRF216A Ambient Light Sensor
> + *
> + * Copyright (C) 2021 Lite-On Technology Corp (Singapore)
> + * Author: Shi Zhigang <Zhigang.Shi@...eon.com>
> + *
> + * IIO driver for LTRF216A (7-bit I2C slave address 0x53).
> + */
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/i2c.h>
> +#include <linux/mutex.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/pm.h>
> +#include <linux/delay.h>
> +
> +#define LTRF216A_DRV_NAME "ltrf216a"
> +
> +#define LTRF216A_MAIN_CTRL		0x00
> +
> +#define LTRF216A_ALS_MEAS_RATE		0x04
> +#define LTRF216A_MAIN_STATUS		0x07
> +#define LTRF216A_CLEAR_DATA_0		0x0A
> +
> +#define LTRF216A_ALS_DATA_0		0x0D
> +
> +static const int int_time_mapping[] = { 400000, 200000, 100000 };
> +
> +struct ltrf216a_data {
> +	struct i2c_client *client;
> +	u32			int_time;
> +	u8			int_time_fac;
> +	u8			als_gain_fac;
> +	struct mutex mutex;
> +};
> +
> +/* open air. need to update based on TP transmission rate. */
> +#define WIN_FAC	1
> +
> +static const struct iio_chan_spec ltrf216a_channels[] = {
> +	{
> +		.type = IIO_LIGHT,
> +		.info_mask_separate =
> +			BIT(IIO_CHAN_INFO_PROCESSED) |
> +			BIT(IIO_CHAN_INFO_INT_TIME),
> +	}
> +};
> +
> +static IIO_CONST_ATTR_INT_TIME_AVAIL("0.1 0.2 0.4");
> +
> +static struct attribute *ltrf216a_attributes[] = {
> +	&iio_const_attr_integration_time_available.dev_attr.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group ltrf216a_attribute_group = {
> +	.attrs = ltrf216a_attributes,
> +};
> +
> +static int ltrf216a_init(struct iio_dev *indio_dev)
> +{
> +	int ret;
> +	struct ltrf216a_data *data = iio_priv(indio_dev);
> +
> +	ret = i2c_smbus_read_byte_data(data->client, LTRF216A_MAIN_CTRL);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "Error reading LTRF216A_MAIN_CTRL\n");
> +		return ret;
> +	}
> +
> +	/* enable sensor */
> +	ret |= 0x02;
> +	ret = i2c_smbus_write_byte_data(data->client, LTRF216A_MAIN_CTRL, ret);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "Error writing LTRF216A_MAIN_CTRL\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int ltrf216a_disable(struct iio_dev *indio_dev)
> +{
> +	int ret;
> +	struct ltrf216a_data *data = iio_priv(indio_dev);
> +
> +	ret = i2c_smbus_write_byte_data(data->client, LTRF216A_MAIN_CTRL, 0);
> +	if (ret < 0)
> +		dev_err(&data->client->dev, "Error writing LTRF216A_MAIN_CTRL\n");
> +
> +	return ret;
> +}
> +
> +static int ltrf216a_set_it_time(struct ltrf216a_data *data, int itime)
> +{
> +	int i, ret, index = -1;
> +	u8 reg;
> +
> +	for (i = 0; i < ARRAY_SIZE(int_time_mapping); i++) {
> +		if (int_time_mapping[i] == itime) {
> +			index = i;
> +			break;
> +		}
> +	}
> +	/* Make sure integration time index is valid */
> +	if (index < 0)
> +		return -EINVAL;
> +
> +	if (index == 0) {
> +		reg = 0x03;
> +		data->int_time_fac = 4;
> +	} else if (index == 1) {
> +		reg = 0x13;
> +		data->int_time_fac = 2;
> +	} else {
> +		reg = (index << 4) | 0x02;
> +		data->int_time_fac = 1;
> +	}
> +
> +	ret = i2c_smbus_write_byte_data(data->client, LTRF216A_ALS_MEAS_RATE, reg);
> +	if (ret < 0)
> +		return ret;
> +
> +	data->int_time = itime;
> +
> +	return 0;
> +}
> +
> +static int ltrf216a_get_it_time(struct ltrf216a_data *data, int *val, int *val2)
> +{
> +	*val = 0;
> +	*val2 = data->int_time;
> +
> +	return IIO_VAL_INT_PLUS_MICRO;
> +}
> +
> +static int ltrf216a_read_data(struct ltrf216a_data *data, u8 addr)
> +{
> +	int ret;
> +	int tries = 25;
> +	int val_0, val_1, val_2;
> +
> +	while (tries--) {
> +		ret = i2c_smbus_read_byte_data(data->client, LTRF216A_MAIN_STATUS);
> +		if (ret < 0)
> +			return ret;
> +		if (ret & 0x08)
> +			break;
> +		msleep(20);
> +	}
> +
> +	val_0 = i2c_smbus_read_byte_data(data->client, addr);
> +	val_1 = i2c_smbus_read_byte_data(data->client, addr + 1);
> +	val_2 = i2c_smbus_read_byte_data(data->client, addr + 2);
> +	ret = (val_2 << 16) + (val_1 << 8) + val_0;
> +
> +	return ret;
> +}
> +
> +static int ltrf216a_get_lux(struct ltrf216a_data *data)
> +{
> +	int greendata, cleardata, lux;
> +
> +	greendata = ltrf216a_read_data(data, LTRF216A_ALS_DATA_0);
> +	cleardata = ltrf216a_read_data(data, LTRF216A_CLEAR_DATA_0);
> +
> +	if (greendata < 0 || cleardata < 0)
> +		lux = 0;
> +	else
> +		lux = greendata * 8 * WIN_FAC / data->als_gain_fac / data->int_time_fac / 10;
> +
> +	return lux;
> +}
> +
> +static int ltrf216a_read_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan, int *val,
> +			     int *val2, long mask)
> +{
> +	int ret;
> +	struct ltrf216a_data *data = iio_priv(indio_dev);
> +
> +	mutex_lock(&data->mutex);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_PROCESSED:
> +		ret = ltrf216a_get_lux(data);
> +		*val = ret;
> +		ret = IIO_VAL_INT;
> +		break;
> +	case IIO_CHAN_INFO_INT_TIME:
> +		ret = ltrf216a_get_it_time(data, val, val2);
> +		break;
> +	default:
> +		ret = -EINVAL;
> +	}
> +
> +	mutex_unlock(&data->mutex);
> +
> +	return ret;
> +}
> +
> +static int ltrf216a_write_raw(struct iio_dev *indio_dev,
> +			      struct iio_chan_spec const *chan, int val,
> +			      int val2, long mask)
> +{
> +	struct ltrf216a_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_INT_TIME:
> +		if (val != 0)
> +			return -EINVAL;
> +		mutex_lock(&data->mutex);
> +		ret = ltrf216a_set_it_time(data, val2);
> +		mutex_unlock(&data->mutex);
> +		return ret;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_info ltrf216a_info = {
> +	.read_raw	= ltrf216a_read_raw,
> +	.write_raw	= ltrf216a_write_raw,
> +	.attrs		= &ltrf216a_attribute_group,
> +};
> +
> +static int ltrf216a_probe(struct i2c_client *client,
> +			  const struct i2c_device_id *id)
> +{
> +	struct ltrf216a_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;
> +
> +	mutex_init(&data->mutex);
> +
> +	indio_dev->info = &ltrf216a_info;
> +	indio_dev->name = LTRF216A_DRV_NAME;
> +	indio_dev->channels = ltrf216a_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(ltrf216a_channels);
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	ret = ltrf216a_init(indio_dev);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "ltrf216a chip init failed\n");
> +		return ret;
> +	}
> +	data->int_time = 100000;
> +	data->int_time_fac = 1;
> +	data->als_gain_fac = 3;
> +
> +	ret = iio_device_register(indio_dev);

Use devm- function, assuming no issues with removal-steps (disable will
be before iio unregister).

> +	if (ret < 0) {
> +		dev_err(&client->dev, "failed to register iio dev\n");
> +		goto err_init;
> +	}
> +
> +	return 0;

Blank line.

> +err_init:
> +	ltrf216a_disable(indio_dev);
> +	return ret;
> +}
> +



Best regards,
Krzysztof

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