/*
   * 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_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] = '
  ';
  
  	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",
  		.pm = BH1750_PM_OPS,
  	},
  	.probe = bh1750_probe,
  	.remove = bh1750_remove,
  	.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");