Date:	Fri, 08 May 2015 10:55:21 -0400
From:	Jonathan Cameron <jic23@...nel.org>
To:	Tomasz Duszynski <tduszyns@...il.com>
CC:	knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
	linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org
Subject: Re: [PATCH v4] iio: light: add support for ROHM BH1710/BH1715/BH1721/BH1750/BH1751
 ambient light sensors

On 03/05/15 14:37, Tomasz Duszynski wrote:
> Add support for ROHM BH1710/BH1715/BH1721/BH1750/BH1751 ambient light
> sensors.
> 
> Signed-off-by: Tomasz Duszynski <tduszyns@...il.com>
Applied to the togreg branch of iio.git which will be pushed out as testing
when I have an internet connection that does more than https...

Anyhow, nice driver, thanks!
> ---
>  Changes in v4:
>  	- Minor changes in module documentation
> 	- Use be16_to_cpu instead of swab16 for clarity
> 
>  Changes in v3:
>  	- Do some code cleanup
> 	- Add comments to clarify non-intuitive driver parts
> 	- Return proper scale value [lx / count] to userspace. In previous
> 	  patches scale inverse was returned.
> 
>  Changes in v2:
>  	- Store chip-dependent values in chip_info structure
> 	- Add bh1750_remove to power down chip (necessary for BH1721)
> 	- Use one time mode for chips that have support for that
> 	- Use IIO_LIGHT instead of IIO_INTENSITY for channel type
> 
>  drivers/iio/light/Kconfig  |  10 ++
>  drivers/iio/light/Makefile |   1 +
>  drivers/iio/light/bh1750.c | 334 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 345 insertions(+)
>  create mode 100644 drivers/iio/light/bh1750.c
> 
> diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
> index 5a3237b..ebc578a 100644
> --- a/drivers/iio/light/Kconfig
> +++ b/drivers/iio/light/Kconfig
> @@ -37,6 +37,16 @@ config APDS9300
>  	 To compile this driver as a module, choose M here: the
>  	 module will be called apds9300.
> 
> +config BH1750
> +	tristate "ROHM BH1750 ambient light sensor"
> +	depends on I2C
> +	help
> +	 Say Y here to build support for the ROHM BH1710, BH1715, BH1721,
> +	 BH1750, BH1751 ambient light sensors.
> +
> +	 To compile this driver as a module, choose M here: the module will
> +	 be called bh1750.
> +
>  config CM32181
>  	depends on I2C
>  	tristate "CM32181 driver"
> diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
> index 74656c1..1a13184 100644
> --- a/drivers/iio/light/Makefile
> +++ b/drivers/iio/light/Makefile
> @@ -6,6 +6,7 @@
>  obj-$(CONFIG_ADJD_S311)		+= adjd_s311.o
>  obj-$(CONFIG_AL3320A)		+= al3320a.o
>  obj-$(CONFIG_APDS9300)		+= apds9300.o
> +obj-$(CONFIG_BH1750)		+= bh1750.o
>  obj-$(CONFIG_CM32181)		+= cm32181.o
>  obj-$(CONFIG_CM36651)		+= cm36651.o
>  obj-$(CONFIG_GP2AP020A00F)	+= gp2ap020a00f.o
> diff --git a/drivers/iio/light/bh1750.c b/drivers/iio/light/bh1750.c
> new file mode 100644
> index 0000000..564c2b3
> --- /dev/null
> +++ b/drivers/iio/light/bh1750.c
> @@ -0,0 +1,334 @@
> +/*
> + * ROHM BH1710/BH1715/BH1721/BH1750/BH1751 ambient light sensor driver
> + *
> + * Copyright (c) Tomasz Duszynski <tduszyns@...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.
> + *
> + * Data sheets:
> + *  http://rohmfs.rohm.com/en/products/databook/datasheet/ic/sensor/light/bh1710fvc-e.pdf
> + *  http://rohmfs.rohm.com/en/products/databook/datasheet/ic/sensor/light/bh1715fvc-e.pdf
> + *  http://rohmfs.rohm.com/en/products/databook/datasheet/ic/sensor/light/bh1721fvc-e.pdf
> + *  http://rohmfs.rohm.com/en/products/databook/datasheet/ic/sensor/light/bh1750fvi-e.pdf
> + *  http://rohmfs.rohm.com/en/products/databook/datasheet/ic/sensor/light/bh1751fvi-e.pdf
> + *
> + * 7-bit I2C slave addresses:
> + *  0x23 (ADDR pin low)
> + *  0x5C (ADDR pin high)
> + *
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/module.h>
> +
> +#define BH1750_POWER_DOWN		0x00
> +#define BH1750_ONE_TIME_H_RES_MODE	0x20 /* auto-mode for BH1721 */
> +#define BH1750_CHANGE_INT_TIME_H_BIT	0x40
> +#define BH1750_CHANGE_INT_TIME_L_BIT	0x60
> +
> +enum {
> +	BH1710,
> +	BH1721,
> +	BH1750,
> +};
> +
> +struct bh1750_chip_info;
> +struct bh1750_data {
> +	struct i2c_client *client;
> +	struct mutex lock;
> +	const struct bh1750_chip_info *chip_info;
> +	u16 mtreg;
> +};
> +
> +struct bh1750_chip_info {
> +	u16 mtreg_min;
> +	u16 mtreg_max;
> +	u16 mtreg_default;
> +	int mtreg_to_usec;
> +	int mtreg_to_scale;
> +
> +	/*
> +	 * For BH1710/BH1721 all possible integration time values won't fit
> +	 * into one page so displaying is limited to every second one.
> +	 * Note, that user can still write proper values which were not
> +	 * listed.
> +	 */
> +	int inc;
> +
> +	u16 int_time_low_mask;
> +	u16 int_time_high_mask;
> +}
> +
> +static const bh1750_chip_info_tbl[] = {
> +	[BH1710] = { 140, 1022, 300, 400,  250000000, 2, 0x001F, 0x03E0 },
> +	[BH1721] = { 140, 1020, 300, 400,  250000000, 2, 0x0010, 0x03E0 },
> +	[BH1750] = { 31,  254,  69,  1740, 57500000,  1, 0x001F, 0x00E0 },
> +};
> +
> +static int bh1750_change_int_time(struct bh1750_data *data, int usec)
> +{
> +	int ret;
> +	u16 val;
> +	u8 regval;
> +	const struct bh1750_chip_info *chip_info = data->chip_info;
> +
> +	if ((usec % chip_info->mtreg_to_usec) != 0)
> +		return -EINVAL;
> +
> +	val = usec / chip_info->mtreg_to_usec;
> +	if (val < chip_info->mtreg_min || val > chip_info->mtreg_max)
> +		return -EINVAL;
> +
> +	ret = i2c_smbus_write_byte(data->client, BH1750_POWER_DOWN);
> +	if (ret < 0)
> +		return ret;
> +
> +	regval = (val & chip_info->int_time_high_mask) >> 5;
> +	ret = i2c_smbus_write_byte(data->client,
> +				   BH1750_CHANGE_INT_TIME_H_BIT | regval);
> +	if (ret < 0)
> +		return ret;
> +
> +	regval = val & chip_info->int_time_low_mask;
> +	ret = i2c_smbus_write_byte(data->client,
> +				   BH1750_CHANGE_INT_TIME_L_BIT | regval);
> +	if (ret < 0)
> +		return ret;
> +
> +	data->mtreg = val;
> +
> +	return 0;
> +}
> +
> +static int bh1750_read(struct bh1750_data *data, int *val)
> +{
> +	int ret;
> +	__be16 result;
> +	const struct bh1750_chip_info *chip_info = data->chip_info;
> +	unsigned long delay = chip_info->mtreg_to_usec * data->mtreg;
> +
> +	/*
> +	 * BH1721 will enter continuous mode on receiving this command.
> +	 * Note, that this eliminates need for bh1750_resume().
> +	 */
> +	ret = i2c_smbus_write_byte(data->client, BH1750_ONE_TIME_H_RES_MODE);
> +	if (ret < 0)
> +		return ret;
> +
> +	usleep_range(delay + 15000, delay + 40000);
> +
> +	ret = i2c_master_recv(data->client, (char *)&result, 2);
> +	if (ret < 0)
> +		return ret;
> +
> +	*val = be16_to_cpu(result);
> +
> +	return 0;
> +}
> +
> +static int bh1750_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan,
> +			   int *val, int *val2, long mask)
> +{
> +	int ret, tmp;
> +	struct bh1750_data *data = iio_priv(indio_dev);
> +	const struct bh1750_chip_info *chip_info = data->chip_info;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		switch (chan->type) {
> +		case IIO_LIGHT:
> +			mutex_lock(&data->lock);
> +			ret = bh1750_read(data, val);
> +			mutex_unlock(&data->lock);
> +			if (ret < 0)
> +				return ret;
> +
> +			return IIO_VAL_INT;
> +		default:
> +			return -EINVAL;
> +		}
> +	case IIO_CHAN_INFO_SCALE:
> +		tmp = chip_info->mtreg_to_scale / data->mtreg;
> +		*val = tmp / 1000000;
> +		*val2 = tmp % 1000000;
> +		return IIO_VAL_INT_PLUS_MICRO;
> +	case IIO_CHAN_INFO_INT_TIME:
> +		*val = 0;
> +		*val2 = chip_info->mtreg_to_usec * data->mtreg;
> +		return IIO_VAL_INT_PLUS_MICRO;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int bh1750_write_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int val, int val2, long mask)
> +{
> +	int ret;
> +	struct bh1750_data *data = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_INT_TIME:
> +		if (val != 0)
> +			return -EINVAL;
> +
> +		mutex_lock(&data->lock);
> +		ret = bh1750_change_int_time(data, val2);
> +		mutex_unlock(&data->lock);
> +		return ret;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static ssize_t bh1750_show_int_time_available(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	int i;
> +	size_t len = 0;
> +	struct bh1750_data *data = iio_priv(dev_to_iio_dev(dev));
> +	const struct bh1750_chip_info *chip_info = data->chip_info;
> +
> +	for (i = chip_info->mtreg_min; i <= chip_info->mtreg_max; i += chip_info->inc)
> +		len += scnprintf(buf + len, PAGE_SIZE - len, "0.%06d ",
> +				 chip_info->mtreg_to_usec * i);
> +
> +	buf[len - 1] = '\n';
> +
> +	return len;
> +}
> +
> +static IIO_DEV_ATTR_INT_TIME_AVAIL(bh1750_show_int_time_available);
> +
> +static struct attribute *bh1750_attributes[] = {
> +	&iio_dev_attr_integration_time_available.dev_attr.attr,
> +	NULL,
> +};
> +
> +static struct attribute_group bh1750_attribute_group = {
> +	.attrs = bh1750_attributes,
> +};
> +
> +static const struct iio_info bh1750_info = {
> +	.driver_module = THIS_MODULE,
> +	.attrs = &bh1750_attribute_group,
> +	.read_raw = bh1750_read_raw,
> +	.write_raw = bh1750_write_raw,
> +};
> +
> +static const struct iio_chan_spec bh1750_channels[] = {
> +	{
> +		.type = IIO_LIGHT,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_SCALE) |
> +				      BIT(IIO_CHAN_INFO_INT_TIME)
> +	}
> +};
> +
> +static int bh1750_probe(struct i2c_client *client,
> +			const struct i2c_device_id *id)
> +{
> +	int ret, usec;
> +	struct bh1750_data *data;
> +	struct iio_dev *indio_dev;
> +
> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
> +				I2C_FUNC_SMBUS_WRITE_BYTE))
> +		return -ENODEV;
> +
> +	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;
> +	data->chip_info = &bh1750_chip_info_tbl[id->driver_data];
> +
> +	usec = data->chip_info->mtreg_to_usec * data->chip_info->mtreg_default;
> +	ret = bh1750_change_int_time(data, usec);
> +	if (ret < 0)
> +		return ret;
> +
> +	mutex_init(&data->lock);
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->info = &bh1750_info;
> +	indio_dev->name = id->name;
> +	indio_dev->channels = bh1750_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(bh1750_channels);
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	return iio_device_register(indio_dev);
> +}
> +
> +static int bh1750_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +	struct bh1750_data *data = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +
> +	mutex_lock(&data->lock);
> +	i2c_smbus_write_byte(client, BH1750_POWER_DOWN);
> +	mutex_unlock(&data->lock);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int bh1750_suspend(struct device *dev)
> +{
> +	int ret;
> +	struct bh1750_data *data =
> +		iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
> +
> +	/*
> +	 * This is mainly for BH1721 which doesn't enter power down
> +	 * mode automatically.
> +	 */
> +	mutex_lock(&data->lock);
> +	ret = i2c_smbus_write_byte(data->client, BH1750_POWER_DOWN);
> +	mutex_unlock(&data->lock);
> +
> +	return ret;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(bh1750_pm_ops, bh1750_suspend, NULL);
> +#define BH1750_PM_OPS (&bh1750_pm_ops)
> +#else
> +#define BH1750_PM_OPS NULL
> +#endif
> +
> +static const struct i2c_device_id bh1750_id[] = {
> +	{ "bh1710", BH1710 },
> +	{ "bh1715", BH1750 },
> +	{ "bh1721", BH1721 },
> +	{ "bh1750", BH1750 },
> +	{ "bh1751", BH1750 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, bh1750_id);
> +
> +static struct i2c_driver bh1750_driver = {
> +	.driver = {
> +		.name = "bh1750",
> +		.owner = THIS_MODULE,
> +		.pm = BH1750_PM_OPS,
> +	},
> +	.probe = bh1750_probe,
> +	.remove = bh1750_remove,
> +	.id_table = bh1750_id,
> +
> +};
> +module_i2c_driver(bh1750_driver);
> +
> +MODULE_AUTHOR("Tomasz Duszynski <tduszyns@...il.com>");
> +MODULE_DESCRIPTION("ROHM BH1710/BH1715/BH1721/BH1750/BH1751 als driver");
> +MODULE_LICENSE("GPL v2");
> --
> 2.3.6
> 
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