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Message-ID: <20150503195232.GA22467@Arch.lan>
Date: Sun, 3 May 2015 21:52:32 +0200
From: Tomasz Duszynski <tduszyns@...il.com>
To: Jonathan Cameron <jic23@...nel.org>
Cc: tduszyns@...il.com, Peter Meerwald <pmeerw@...erw.net>,
knaack.h@....de, lars@...afoo.de, linux-kernel@...r.kernel.org,
linux-iio@...r.kernel.org
Subject: Re: [PATCH v3] iio: light: add support for ROHM
BH1710/BH1715/BH1721/BH1750/BH1751 ambient light sensors
On Sun, May 03, 2015 at 08:10:15PM +0100, Jonathan Cameron wrote:
> On 28/04/15 21:27, tduszyns@...il.com wrote:
> > On Mon, Apr 27, 2015 at 11:28:32PM +0200, Peter Meerwald wrote:
> >>
> >>> Add support for ROHM BH1710/BH1715/BH1721/BH1750/BH1751 ambient light
> >>> sensors.
> >>
> >> some minor comments below
> >>
> >>> Signed-off-by: Tomasz Duszynski <tduszyns@...il.com>
> >>> ---
> >>> 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..9635a45
> >>> --- /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;
> >>> + u16 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 auto mode on receiving this command.
> >>
> >> maybe drop 'auto'?
> >>
> > OK, no problem for me.
> >>> + * 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 = swab16(result);
> >>
> >> I think be16_to_cpu() would be much clearer;
> >> is swab16() correct on big-endian machines?
> >>
> > b16_to_cpu() totally fine for me.
> >
> > Correct me if I am wrong but I think swab16 here has to do with
> > i2c protocol vs chip endianess not host endianess. Guess it will work equally
> > good on both BE/LE machines.
> That would have applied one of the specific length i2c commands was used.
> The transmission for i2c should in theory be little endian,(but often isn't)
> It is to deal with these case that we have the swapped functions.
> i2c_smbus_write_word_swapped for example.
>
> Here the i2c subsystem has no way of knowing if you are reading two 1 byte
> registers or 1 2 byte register. Hence it can't do the reordering and will
> present them as a pair of bytes in whatever the wire order was.
>
> Hence you need to convert manually from bus endianness (whatever it is)
> to cpu endianness.
>
>
>
Thanks for clarifying this. Anyway, I replaced swab16() with be16_to_cpu()
in V4.
> >>> +
> >>> + 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
> >>>
> >>
> >> --
> >>
> >> Peter Meerwald
> >> +43-664-2444418 (mobile)
>
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