Date:	Tue, 28 Apr 2015 22:40:57 +0200
From:	Tomasz Duszynski <tduszyns@...il.com>
To:	jic23@...nel.org
Cc:	knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
	tduszyns@...il.com, linux-kernel@...r.kernel.org,
	linux-iio@...r.kernel.org
Subject: [PATCH v4] iio: light: add support for ROHM BH1710/BH1715/BH1721/BH1750/BH1751 ambient light sensors

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

Signed-off-by: Tomasz Duszynski <tduszyns@...il.com>
---
 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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