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SubjectRe: [PATCH] iio: light: add support for ROHM BH1710/BH1715/BH1721/BH1750/BH1751 ambient light sensors
On Tue, 21 Apr 2015, Tomasz Duszynski wrote:

> Add support for ROHM BH1710/BH1715/BH1721/BH1750/BH1751 ambient light
> sensors.

nice, some comments inline

> Signed-off-by: Tomasz Duszynski <tduszyns@gmail.com>
> ---
> drivers/iio/light/Kconfig | 10 ++
> drivers/iio/light/Makefile | 1 +
> drivers/iio/light/bh1750.c | 322 +++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 333 insertions(+)
> create mode 100644 drivers/iio/light/bh1750.c
>
> diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
> index 5a3237b..9fb79ca 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 "BH1750 ambient light sensor"
> + depends on I2C
> + help
> + Say Y here to build support for the 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..83b5413
> --- /dev/null
> +++ b/drivers/iio/light/bh1750.c
> @@ -0,0 +1,322 @@
> +/*
> + * ROHM BH1710/BH1715/BH1721/BH1750/BH1751 ambient light sensor driver
> + *
> + * Copyright (c) Tomasz Duszynski <tduszyns@gmail.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_H_RES_MODE 0x10 /* auto-mode for BH1721 */
> +#define BH1750_CHANGE_INT_TIME_H_BIT 0x40
> +#define BH1750_CHANGE_INT_TIME_L_BIT 0x60
> +
> +enum {
> + BH1710,
> + BH1715,
> + BH1721,
> + BH1750,
> + BH1751
> +};
> +
> +struct bh1750_chip_info {
> + int id;

why is the id stored in chip_info?
the point of the chip_info table is to avoid switch blocks in the driver;
I suggest to move remaining chip-dependent values to the table and drop
the id

> + int mtreg_min;
> + int mtreg_max;
> + int mtreg_default;

u16, these are values stored in an u16 register

> + int mtreg_to_usec;
> + int mtreg_to_scale;
> +};
> +
> +struct bh1750_data {
> + struct i2c_client *client;
> + struct mutex lock;
> + const struct bh1750_chip_info *chip_info;
> + u16 mtreg;
> +};
> +
> +static const struct bh1750_chip_info chip_info_tbl[] = {
> + [BH1710] = { BH1710, 140, 1022, 300, 400, 4000 },
> + [BH1715] = { BH1715, 31, 254, 69, 1740, 17391 },
> + [BH1721] = { BH1721, 140, 1020, 300, 400, 4000 },
> + [BH1750] = { BH1750, 31, 254, 69, 1740, 17391 },
> + [BH1751] = { BH1751, 31, 254, 69, 1740, 17391 }
> +};
> +
> +static int bh1750_change_int_time(struct bh1750_data *data, int usec)
> +{
> + int ret, val;
> + u8 low = 0, high = 0;

initialization not needed, low/high should always be set

> + 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;
> +
> + switch (chip_info->id) {
> + case BH1710:
> + low = val & 0x001F;
> + high = (val & 0x03E0) >> 5;
> + break;
> + case BH1721:
> + low = val & 0x0010;
> + high = (val & 0x03E0) >> 5;

break missing?

> + case BH1715:
> + case BH1750:
> + case BH1751:
> + low = val & 0x001F;
> + high = (val & 0x00E0) >> 5;
> + break;
> + }
> +
> + ret = i2c_smbus_write_byte(data->client, BH1750_POWER_DOWN);
> + if (ret < 0)
> + return ret;
> +
> + ret = i2c_smbus_write_byte(data->client,
> + BH1750_CHANGE_INT_TIME_H_BIT | high);
> + if (ret < 0)
> + return ret;
> +
> + ret = i2c_smbus_write_byte(data->client,
> + BH1750_CHANGE_INT_TIME_L_BIT | low);
> + if (ret < 0)
> + return ret;
> +
> + data->mtreg = val;
> +
> + return i2c_smbus_write_byte(data->client, BH1750_H_RES_MODE);
> +}
> +
> +static int bh1750_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + u16 result;
> + int ret, tmp;
> + unsigned long delay;
> + 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_INTENSITY:
> + delay = chip_info->mtreg_to_usec * data->mtreg;
> + mutex_lock(&data->lock);
> + usleep_range(delay, delay + 20000);

the driver uses continuous mode and there is no data-ready flag

why not using one time mode?, I think this would better fit in what other
drivers are doing

> + ret = i2c_master_recv(data->client,
> + (char *)&result, 2);

almost all drivers use i2c_smbus_read_word_xxx() -- is there a reason not
to?

> + mutex_unlock(&data->lock);
> + if (ret < 0)
> + return ret;
> +
> + *val = swab16(result);
> + return IIO_VAL_INT;
> + default:
> + return -EINVAL;
> + }
> + case IIO_CHAN_INFO_SCALE:
> + tmp = chip_info->mtreg_to_scale * data->mtreg;

use the variable delay as above; the same computation is done in every
switch case

> + *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, inc;
> + 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;
> +
> + switch (chip_info->id) {
> + case BH1710:
> + case BH1721:
> + /* All values won't fit into one page, so display every
> + * second one. By doing so step size is increased
> + * from 0.4ms to 0.8ms.*/

multi-line comment style?;
missing space before */

> + inc = 2;
> + break;
> + default:
> + inc = 1;
> + break;
> + }
> +
> + for (i = chip_info->mtreg_min; i <= chip_info->mtreg_max; i += inc)
> + len += scnprintf(buf + len, PAGE_SIZE - len, "0.%06d ",
> + i * chip_info->mtreg_to_usec);
> +
> + 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_INTENSITY,
> + .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 = &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 devm_iio_device_register(&client->dev, indio_dev);

chip should probably be powered down if this fails; or use one-time mode

> +}
> +
> +#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)));
> +
> + mutex_lock(&data->lock);
> + ret = i2c_smbus_write_byte(data->client, BH1750_POWER_DOWN);
> + mutex_unlock(&data->lock);
> +
> + return ret;
> +}
> +
> +static int bh1750_resume(struct device *dev)
> +{
> + struct bh1750_data *data =
> + iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
> +
> + return i2c_smbus_write_byte(data->client, BH1750_H_RES_MODE);
> +}
> +
> +static SIMPLE_DEV_PM_OPS(bh1750_pm_ops, bh1750_suspend, bh1750_resume);
> +#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", BH1715 },
> + { "bh1721", BH1721 },
> + { "bh1750", BH1750 },
> + { "bh1751", BH1751 },
> + { }
> +};
> +MODULE_DEVICE_TABLE(i2c, bh1750_id);
> +
> +static struct i2c_driver bh1750_driver = {
> + .driver = {
> + .name = "bh1750",
> + .owner = THIS_MODULE,
> + .pm = BH1750_PM_OPS,
> + },

.remove to power down

> + .probe = bh1750_probe,
> + .id_table = bh1750_id,
> +
> +};
> +module_i2c_driver(bh1750_driver);
> +
> +MODULE_AUTHOR("Tomasz Duszynski <tduszyns@gmail.com>");
> +MODULE_DESCRIPTION("ROHM BH1710/BH1715/BH1721/BH1750/BH1751 als driver");
> +MODULE_LICENSE("GPL v2");
>

--

Peter Meerwald
+43-664-2444418 (mobile)


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