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Date:	Thu, 21 Aug 2014 15:04:02 +0200 (CEST)
From:	Peter Meerwald <pmeerw@...erw.net>
To:	Daniel Baluta <daniel.baluta@...el.com>
cc:	jic23@...nel.org, linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org, Tsechih_Lin@...s.com
Subject: Re: [PATCH] iio: Add Dyna-Image AL3320A ambient light sensor
 driver


> Minimal implementation. This driver provides raw illuminance readings.
> 
> This is based on drivers/hwmon/al3320.c (*) driver from msm tree written
> by Tsechih Lin <Tsechih_Lin@...s.com>
> 
> * https://android.googlesource.com/kernel/msm.git
> 
> Signed-off-by: Daniel Baluta <daniel.baluta@...el.com>

comments inline below

> ---
>  drivers/iio/light/Kconfig   |  10 ++
>  drivers/iio/light/Makefile  |   1 +
>  drivers/iio/light/al3320a.c | 261 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 272 insertions(+)
>  create mode 100644 drivers/iio/light/al3320a.c
> 
> diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
> index bf05ca5..5bea821 100644
> --- a/drivers/iio/light/Kconfig
> +++ b/drivers/iio/light/Kconfig
> @@ -17,6 +17,16 @@ config ADJD_S311
>  	 This driver can also be built as a module.  If so, the module
>  	 will be called adjd_s311.
>  
> +config AL3320A
> +	tristate "AL3320A ambient light sensor"
> +	depends on I2C
> +	help
> +	 Say Y here if you want to build a driver for the Dyna Image AL3320A
> +	 ambient light sensor.
> +
> +	 To compile this driver as a module, choose M here: the
> +	 module will be called al3320a.
> +
>  config APDS9300
>  	tristate "APDS9300 ambient light sensor"
>  	depends on I2C
> diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
> index 8b8c09f..47877a3 100644
> --- a/drivers/iio/light/Makefile
> +++ b/drivers/iio/light/Makefile
> @@ -4,6 +4,7 @@
>  
>  # When adding new entries keep the list in alphabetical order
>  obj-$(CONFIG_ADJD_S311)		+= adjd_s311.o
> +obj-$(CONFIG_AL3320A)		+= al3320a.o
>  obj-$(CONFIG_APDS9300)		+= apds9300.o
>  obj-$(CONFIG_CM32181)		+= cm32181.o
>  obj-$(CONFIG_CM36651)		+= cm36651.o
> diff --git a/drivers/iio/light/al3320a.c b/drivers/iio/light/al3320a.c
> new file mode 100644
> index 0000000..06ab557
> --- /dev/null
> +++ b/drivers/iio/light/al3320a.c
> @@ -0,0 +1,261 @@
> +/*
> + * AL3320A - Dyna Image Ambient Light Sensor
> + *
> + * Copyright (c) 2014, Intel Corporation.
> + *
> + * This file is subject to the terms and conditions of version 2 of
> + * the GNU General Public License.  See the file COPYING in the main
> + * directory of this archive for more details.
> + *
> + * IIO driver for AL3320A (7-bit I2C slave address 0x1C).
> + *
> + * TODO: interrupt support
> + *
> + */
> +
> +#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>
> +
> +#define AL3320A_DRV_NAME "al3320a"
> +
> +#define AL3320A_REG_CONFIG		0x00
> +#define AL3320A_REG_STATUS		0x01
> +#define AL3320A_REG_INT			0x02
> +#define AL3320A_REG_WAIT		0x06
> +#define AL3320A_REG_CONFIG_RANGE	0x07
> +#define AL3320A_REG_PERSIST		0x08
> +#define AL3320A_REG_MEAN_TIME		0x09
> +#define AL3320A_REG_ADUMMY		0x0A
> +#define AL3320A_REG_DATA_LOW		0x22
> +#define AL3320A_REG_DATA_HIGH		0x23
> +
> +#define AL3320A_REG_LOW_THRESH_LOW	0x30
> +#define AL3320A_REG_LOW_THRESH_HIGH	0x31
> +#define AL3320A_REG_HIGH_THRESH_LOW	0x32
> +#define AL3320A_REG_HIGH_THRESH_HIGH	0x33
> +
> +#define AL3320A_CONFIG_DISABLE		0x00
> +#define AL3320A_CONFIG_ENABLE		BIT(0)
> +#define AL3320A_CONFIG_SW_RESET		BIT(2)
> +
> +#define AL3320A_GAIN_SHIFT		1
> +
> +/* chip params default values */
> +#define AL3320A_DEFAULT_MEAN_TIME	4
> +#define AL3320A_DEFAULT_WAIT_TIME	0 /* no waiting */
> +
> +enum al3320a_range {
> +	AL3320A_RANGE_1, /* 33.28K lux */
> +	AL3320A_RANGE_2, /* 8.32K lux  */
> +	AL3320A_RANGE_3, /* 2.08K lux  */
> +	AL3320A_RANGE_4  /* 0.65K lux  */
> +};
> +
> +static const int al3320a_scales[][2] = {
> +	{0, 512000}, {0, 128000}, {0, 32000}, {0, 10000}
> +};
> +
> +struct al3320a_data {
> +	struct i2c_client *client;
> +	u8 range;
> +};
> +
> +static const struct iio_chan_spec al3320a_channels[] = {
> +	{
> +		.type	= IIO_LIGHT,
> +		.info_mask_separate =
> +			BIT(IIO_CHAN_INFO_RAW) |
> +			BIT(IIO_CHAN_INFO_SCALE),
> +	}
> +};
> +

not sure if the minimal function below add to clarity or not...
the datatype for gain, mean_time, etc. could be u8

> +static int al3320a_enable(struct al3320a_data *data)
> +{
> +	return i2c_smbus_write_byte_data(data->client, AL3320A_REG_CONFIG,
> +					 AL3320A_CONFIG_ENABLE);
> +}
> +
> +static int al3320a_disable(struct al3320a_data *data)
> +{
> +	return i2c_smbus_write_byte_data(data->client, AL3320A_REG_CONFIG,
> +					 AL3320A_CONFIG_DISABLE);
> +}
> +
> +static int al3320a_set_config_range(struct al3320a_data *data, int gain)
> +{
> +	data->range = gain;
> +
> +	return i2c_smbus_write_byte_data(data->client, AL3320A_REG_CONFIG_RANGE,
> +					 gain << AL3320A_GAIN_SHIFT);
> +}
> +
> +static int al3320a_set_mean_time(struct al3320a_data *data, int mean_time)
> +{
> +	return i2c_smbus_write_byte_data(data->client, AL3320A_REG_MEAN_TIME,
> +					 mean_time);
> +}
> +
> +static int al3320a_set_wait_time(struct al3320a_data *data, int wait_time)
> +{
> +	return i2c_smbus_write_byte_data(data->client, AL3320A_REG_WAIT,
> +					 wait_time);
> +}
> +
> +static int al3320a_get_adc_value(struct al3320a_data *data)
> +{
> +	unsigned int low, high;
> +

could use a single i2c_smbus_read_word_swapped() instead of this function

> +	high = i2c_smbus_read_byte_data(data->client, AL3320A_REG_DATA_HIGH);
> +	if (high < 0)
> +		return high;
> +
> +	low = i2c_smbus_read_byte_data(data->client, AL3320A_REG_DATA_LOW);
> +	if (low < 0)
> +		return low;
> +	return (high << 8) | low;
> +}
> +
> +static int al3320a_init(struct al3320a_data *data)
> +{
> +	int ret;
> +
> +	/*  power on */

extra space before power

> +	ret = al3320a_enable(data);
> +	if (ret)
> +		return ret;
> +
> +	ret = al3320a_set_config_range(data, AL3320A_RANGE_3);
> +	if (ret)
> +		return ret;
> +
> +	ret = al3320a_set_mean_time(data, AL3320A_DEFAULT_MEAN_TIME);
> +	if (ret)
> +		return ret;
> +
> +	ret = al3320a_set_wait_time(data, AL3320A_DEFAULT_WAIT_TIME);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int al3320a_read_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int *val,
> +			    int *val2,
> +			    long mask)
> +{
> +	struct al3320a_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		ret = al3320a_get_adc_value(data);
> +		if (ret < 0)
> +			return ret;
> +		*val = ret;
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = al3320a_scales[data->range][0];
> +		*val2 = al3320a_scales[data->range][1];
> +		return IIO_VAL_INT_PLUS_MICRO;
> +	}
> +	return -EINVAL;
> +}
> +
> +static int al3320a_write_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     int val, int val2, long mask)
> +{
> +	struct al3320a_data *data = iio_priv(indio_dev);
> +	int i;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SCALE:
> +		for (i = 0; i < ARRAY_SIZE(al3320a_scales); i++) {
> +			if (val == al3320a_scales[i][0] &&
> +			    val2 == al3320a_scales[i][1]) {
> +				data->range = i;

strictly, should try to write the range value and only on success update 
data->range

data->range is also set in _set_config_range(), done twice!

> +				return al3320a_set_config_range(data, i);
> +			}
> +		}
> +	}
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info al3320a_info = {
> +	.driver_module	= THIS_MODULE,
> +	.read_raw	= al3320a_read_raw,
> +	.write_raw	= al3320a_write_raw,
> +};
> +
> +static int al3320a_probe(struct i2c_client *client,
> +			 const struct i2c_device_id *id)
> +{
> +	struct al3320a_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 = &al3320a_info;
> +	indio_dev->name = AL3320A_DRV_NAME;
> +	indio_dev->channels = al3320a_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(al3320a_channels);
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	ret = al3320a_init(data);
> +

remove extra newline?

> +	if (ret < 0)

all the check in _init() are
if (ret) return ret;
but here you check ret < 0

> +		return ret;
> +
> +	return iio_device_register(indio_dev);

devm_iio_device_register...?

> +}
> +
> +static int al3320a_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +	struct al3320a_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	iio_device_unregister(indio_dev);
> +
> +	ret = al3320a_disable(data);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id al3320a_id[] = {
> +	{"al3320a", 0},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, al3320a_id);
> +
> +static struct i2c_driver al3320a_driver = {
> +	.driver = {
> +		.name = AL3320A_DRV_NAME,
> +	},
> +	.probe		= al3320a_probe,
> +	.remove		= al3320a_remove,
> +	.id_table	= al3320a_id,
> +};
> +
> +module_i2c_driver(al3320a_driver);
> +
> +MODULE_AUTHOR("Daniel Baluta <daniel.baluta@...el.com>");
> +MODULE_DESCRIPTION("AL3320A Ambient Light Sensor driver");
> +MODULE_LICENSE("GPL v2");
> 

-- 

Peter Meerwald
+43-664-2444418 (mobile)
--
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