/*
   * RPR-0521 ROHM Ambient Light and Proximity Sensor
   *
   * Copyright (c) 2015, Intel Corporation.
   *
   * This file is subject to the terms and conditions of version 2 of
   * the GNU General Public License.  See the file COPYING in the main
   * directory of this archive for more details.
   *
   * IIO driver for RPR-0521RS (7-bit I2C slave address 0x38).
   *
   * TODO: illuminance channel, PM support, buffer
   */
  
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/i2c.h>
  #include <linux/regmap.h>
  #include <linux/delay.h>
  #include <linux/acpi.h>
  
  #include <linux/iio/iio.h>
  #include <linux/iio/sysfs.h>
  #include <linux/pm_runtime.h>
  
  #define RPR0521_REG_SYSTEM_CTRL		0x40
  #define RPR0521_REG_MODE_CTRL		0x41
  #define RPR0521_REG_ALS_CTRL		0x42
  #define RPR0521_REG_PXS_CTRL		0x43
  #define RPR0521_REG_PXS_DATA		0x44 /* 16-bit, little endian */
  #define RPR0521_REG_ALS_DATA0		0x46 /* 16-bit, little endian */
  #define RPR0521_REG_ALS_DATA1		0x48 /* 16-bit, little endian */
  #define RPR0521_REG_ID			0x92
  
  #define RPR0521_MODE_ALS_MASK		BIT(7)
  #define RPR0521_MODE_PXS_MASK		BIT(6)
  #define RPR0521_MODE_MEAS_TIME_MASK	GENMASK(3, 0)
  #define RPR0521_ALS_DATA0_GAIN_MASK	GENMASK(5, 4)
  #define RPR0521_ALS_DATA0_GAIN_SHIFT	4
  #define RPR0521_ALS_DATA1_GAIN_MASK	GENMASK(3, 2)
  #define RPR0521_ALS_DATA1_GAIN_SHIFT	2
  #define RPR0521_PXS_GAIN_MASK		GENMASK(5, 4)
  #define RPR0521_PXS_GAIN_SHIFT		4
  
  #define RPR0521_MODE_ALS_ENABLE		BIT(7)
  #define RPR0521_MODE_ALS_DISABLE	0x00
  #define RPR0521_MODE_PXS_ENABLE		BIT(6)
  #define RPR0521_MODE_PXS_DISABLE	0x00
  
  #define RPR0521_MANUFACT_ID		0xE0
  #define RPR0521_DEFAULT_MEAS_TIME	0x06 /* ALS - 100ms, PXS - 100ms */
  
  #define RPR0521_DRV_NAME		"RPR0521"
  #define RPR0521_REGMAP_NAME		"rpr0521_regmap"
  
  #define RPR0521_SLEEP_DELAY_MS	2000
  
  #define RPR0521_ALS_SCALE_AVAIL "0.007812 0.015625 0.5 1"
  #define RPR0521_PXS_SCALE_AVAIL "0.125 0.5 1"
  
  struct rpr0521_gain {
  	int scale;
  	int uscale;
  };
  
  static const struct rpr0521_gain rpr0521_als_gain[4] = {
  	{1, 0},		/* x1 */
  	{0, 500000},	/* x2 */
  	{0, 15625},	/* x64 */
  	{0, 7812},	/* x128 */
  };
  
  static const struct rpr0521_gain rpr0521_pxs_gain[3] = {
  	{1, 0},		/* x1 */
  	{0, 500000},	/* x2 */
  	{0, 125000},	/* x4 */
  };
  
  enum rpr0521_channel {
  	RPR0521_CHAN_ALS_DATA0,
  	RPR0521_CHAN_ALS_DATA1,
  	RPR0521_CHAN_PXS,
  };
  
  struct rpr0521_reg_desc {
  	u8 address;
  	u8 device_mask;
  };
  
  static const struct rpr0521_reg_desc rpr0521_data_reg[] = {
  	[RPR0521_CHAN_ALS_DATA0] = {
  		.address	= RPR0521_REG_ALS_DATA0,
  		.device_mask	= RPR0521_MODE_ALS_MASK,
  	},
  	[RPR0521_CHAN_ALS_DATA1] = {
  		.address	= RPR0521_REG_ALS_DATA1,
  		.device_mask	= RPR0521_MODE_ALS_MASK,
  	},
  	[RPR0521_CHAN_PXS]	= {
  		.address	= RPR0521_REG_PXS_DATA,
  		.device_mask	= RPR0521_MODE_PXS_MASK,
  	},
  };
  
  static const struct rpr0521_gain_info {
  	u8 reg;
  	u8 mask;
  	u8 shift;
  	const struct rpr0521_gain *gain;
  	int size;
  } rpr0521_gain[] = {
  	[RPR0521_CHAN_ALS_DATA0] = {
  		.reg	= RPR0521_REG_ALS_CTRL,
  		.mask	= RPR0521_ALS_DATA0_GAIN_MASK,
  		.shift	= RPR0521_ALS_DATA0_GAIN_SHIFT,
  		.gain	= rpr0521_als_gain,
  		.size	= ARRAY_SIZE(rpr0521_als_gain),
  	},
  	[RPR0521_CHAN_ALS_DATA1] = {
  		.reg	= RPR0521_REG_ALS_CTRL,
  		.mask	= RPR0521_ALS_DATA1_GAIN_MASK,
  		.shift	= RPR0521_ALS_DATA1_GAIN_SHIFT,
  		.gain	= rpr0521_als_gain,
  		.size	= ARRAY_SIZE(rpr0521_als_gain),
  	},
  	[RPR0521_CHAN_PXS] = {
  		.reg	= RPR0521_REG_PXS_CTRL,
  		.mask	= RPR0521_PXS_GAIN_MASK,
  		.shift	= RPR0521_PXS_GAIN_SHIFT,
  		.gain	= rpr0521_pxs_gain,
  		.size	= ARRAY_SIZE(rpr0521_pxs_gain),
  	},
  };
  
  struct rpr0521_data {
  	struct i2c_client *client;
  
  	/* protect device params updates (e.g state, gain) */
  	struct mutex lock;
  
  	/* device active status */
  	bool als_dev_en;
  	bool pxs_dev_en;
  
  	/* optimize runtime pm ops - enable device only if needed */
  	bool als_ps_need_en;
  	bool pxs_ps_need_en;
  
  	struct regmap *regmap;
  };
  
  static IIO_CONST_ATTR(in_intensity_scale_available, RPR0521_ALS_SCALE_AVAIL);
  static IIO_CONST_ATTR(in_proximity_scale_available, RPR0521_PXS_SCALE_AVAIL);
  
  static struct attribute *rpr0521_attributes[] = {
  	&iio_const_attr_in_intensity_scale_available.dev_attr.attr,
  	&iio_const_attr_in_proximity_scale_available.dev_attr.attr,
  	NULL,
  };
  
  static const struct attribute_group rpr0521_attribute_group = {
  	.attrs = rpr0521_attributes,
  };
  
  static const struct iio_chan_spec rpr0521_channels[] = {
  	{
  		.type = IIO_INTENSITY,
  		.modified = 1,
  		.address = RPR0521_CHAN_ALS_DATA0,
  		.channel2 = IIO_MOD_LIGHT_BOTH,
  		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
  			BIT(IIO_CHAN_INFO_SCALE),
  	},
  	{
  		.type = IIO_INTENSITY,
  		.modified = 1,
  		.address = RPR0521_CHAN_ALS_DATA1,
  		.channel2 = IIO_MOD_LIGHT_IR,
  		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
  			BIT(IIO_CHAN_INFO_SCALE),
  	},
  	{
  		.type = IIO_PROXIMITY,
  		.address = RPR0521_CHAN_PXS,
  		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
  			BIT(IIO_CHAN_INFO_SCALE),
  	}
  };
  
  static int rpr0521_als_enable(struct rpr0521_data *data, u8 status)
  {
  	int ret;
  
  	ret = regmap_update_bits(data->regmap, RPR0521_REG_MODE_CTRL,
  				 RPR0521_MODE_ALS_MASK,
  				 status);
  	if (ret < 0)
  		return ret;
  
  	data->als_dev_en = true;
  
  	return 0;
  }
  
  static int rpr0521_pxs_enable(struct rpr0521_data *data, u8 status)
  {
  	int ret;
  
  	ret = regmap_update_bits(data->regmap, RPR0521_REG_MODE_CTRL,
  				 RPR0521_MODE_PXS_MASK,
  				 status);
  	if (ret < 0)
  		return ret;
  
  	data->pxs_dev_en = true;
  
  	return 0;
  }
  
  /**
   * rpr0521_set_power_state - handles runtime PM state and sensors enabled status
   *
   * @data: rpr0521 device private data
   * @on: state to be set for devices in @device_mask
   * @device_mask: bitmask specifying for which device we need to update @on state
   *
   * We rely on rpr0521_runtime_resume to enable our @device_mask devices, but
   * if (for example) PXS was enabled (pxs_dev_en = true) by a previous call to
   * rpr0521_runtime_resume and we want to enable ALS we MUST set ALS enable
   * bit of RPR0521_REG_MODE_CTRL here because rpr0521_runtime_resume will not
   * be called twice.
   */
  static int rpr0521_set_power_state(struct rpr0521_data *data, bool on,
  				   u8 device_mask)
  {
  #ifdef CONFIG_PM
  	int ret;
  	u8 update_mask = 0;
  
  	if (device_mask & RPR0521_MODE_ALS_MASK) {
  		if (on && !data->als_ps_need_en && data->pxs_dev_en)
  			update_mask |= RPR0521_MODE_ALS_MASK;
  		else
  			data->als_ps_need_en = on;
  	}
  
  	if (device_mask & RPR0521_MODE_PXS_MASK) {
  		if (on && !data->pxs_ps_need_en && data->als_dev_en)
  			update_mask |= RPR0521_MODE_PXS_MASK;
  		else
  			data->pxs_ps_need_en = on;
  	}
  
  	if (update_mask) {
  		ret = regmap_update_bits(data->regmap, RPR0521_REG_MODE_CTRL,
  					 update_mask, update_mask);
  		if (ret < 0)
  			return ret;
  	}
  
  	if (on) {
  		ret = pm_runtime_get_sync(&data->client->dev);
  	} else {
  		pm_runtime_mark_last_busy(&data->client->dev);
  		ret = pm_runtime_put_autosuspend(&data->client->dev);
  	}
  	if (ret < 0) {
  		dev_err(&data->client->dev,
  			"Failed: rpr0521_set_power_state for %d, ret %d
  ",
  			on, ret);
  		if (on)
  			pm_runtime_put_noidle(&data->client->dev);
  
  		return ret;
  	}
  #endif
  	return 0;
  }
  
  static int rpr0521_get_gain(struct rpr0521_data *data, int chan,
  			    int *val, int *val2)
  {
  	int ret, reg, idx;
  
  	ret = regmap_read(data->regmap, rpr0521_gain[chan].reg, &reg);
  	if (ret < 0)
  		return ret;
  
  	idx = (rpr0521_gain[chan].mask & reg) >> rpr0521_gain[chan].shift;
  	*val = rpr0521_gain[chan].gain[idx].scale;
  	*val2 = rpr0521_gain[chan].gain[idx].uscale;
  
  	return 0;
  }
  
  static int rpr0521_set_gain(struct rpr0521_data *data, int chan,
  			    int val, int val2)
  {
  	int i, idx = -EINVAL;
  
  	/* get gain index */
  	for (i = 0; i < rpr0521_gain[chan].size; i++)
  		if (val == rpr0521_gain[chan].gain[i].scale &&
  		    val2 == rpr0521_gain[chan].gain[i].uscale) {
  			idx = i;
  			break;
  		}
  
  	if (idx < 0)
  		return idx;
  
  	return regmap_update_bits(data->regmap, rpr0521_gain[chan].reg,
  				  rpr0521_gain[chan].mask,
  				  idx << rpr0521_gain[chan].shift);
  }
  
  static int rpr0521_read_raw(struct iio_dev *indio_dev,
  			    struct iio_chan_spec const *chan, int *val,
  			    int *val2, long mask)
  {
  	struct rpr0521_data *data = iio_priv(indio_dev);
  	int ret;
  	u8 device_mask;
  	__le16 raw_data;
  
  	switch (mask) {
  	case IIO_CHAN_INFO_RAW:
  		if (chan->type != IIO_INTENSITY && chan->type != IIO_PROXIMITY)
  			return -EINVAL;
  
  		device_mask = rpr0521_data_reg[chan->address].device_mask;
  
  		mutex_lock(&data->lock);
  		ret = rpr0521_set_power_state(data, true, device_mask);
  		if (ret < 0) {
  			mutex_unlock(&data->lock);
  			return ret;
  		}
  
  		ret = regmap_bulk_read(data->regmap,
  				       rpr0521_data_reg[chan->address].address,
  				       &raw_data, 2);
  		if (ret < 0) {
  			rpr0521_set_power_state(data, false, device_mask);
  			mutex_unlock(&data->lock);
  			return ret;
  		}
  
  		ret = rpr0521_set_power_state(data, false, device_mask);
  		mutex_unlock(&data->lock);
  		if (ret < 0)
  			return ret;
  
  		*val = le16_to_cpu(raw_data);
  
  		return IIO_VAL_INT;
  	case IIO_CHAN_INFO_SCALE:
  		mutex_lock(&data->lock);
  		ret = rpr0521_get_gain(data, chan->address, val, val2);
  		mutex_unlock(&data->lock);
  		if (ret < 0)
  			return ret;
  
  		return IIO_VAL_INT_PLUS_MICRO;
  	default:
  		return -EINVAL;
  	}
  }
  
  static int rpr0521_write_raw(struct iio_dev *indio_dev,
  			     struct iio_chan_spec const *chan, int val,
  			     int val2, long mask)
  {
  	struct rpr0521_data *data = iio_priv(indio_dev);
  	int ret;
  
  	switch (mask) {
  	case IIO_CHAN_INFO_SCALE:
  		mutex_lock(&data->lock);
  		ret = rpr0521_set_gain(data, chan->address, val, val2);
  		mutex_unlock(&data->lock);
  
  		return ret;
  	default:
  		return -EINVAL;
  	}
  }
  
  static const struct iio_info rpr0521_info = {
  	.driver_module	= THIS_MODULE,
  	.read_raw	= rpr0521_read_raw,
  	.write_raw	= rpr0521_write_raw,
  	.attrs		= &rpr0521_attribute_group,
  };
  
  static int rpr0521_init(struct rpr0521_data *data)
  {
  	int ret;
  	int id;
  
  	ret = regmap_read(data->regmap, RPR0521_REG_ID, &id);
  	if (ret < 0) {
  		dev_err(&data->client->dev, "Failed to read REG_ID register
  ");
  		return ret;
  	}
  
  	if (id != RPR0521_MANUFACT_ID) {
  		dev_err(&data->client->dev, "Wrong id, got %x, expected %x
  ",
  			id, RPR0521_MANUFACT_ID);
  		return -ENODEV;
  	}
  
  	/* set default measurement time - 100 ms for both ALS and PS */
  	ret = regmap_update_bits(data->regmap, RPR0521_REG_MODE_CTRL,
  				 RPR0521_MODE_MEAS_TIME_MASK,
  				 RPR0521_DEFAULT_MEAS_TIME);
  	if (ret) {
  		pr_err("regmap_update_bits returned %d
  ", ret);
  		return ret;
  	}
  
  	ret = rpr0521_als_enable(data, RPR0521_MODE_ALS_ENABLE);
  	if (ret < 0)
  		return ret;
  	ret = rpr0521_pxs_enable(data, RPR0521_MODE_PXS_ENABLE);
  	if (ret < 0)
  		return ret;
  
  	return 0;
  }
  
  static int rpr0521_poweroff(struct rpr0521_data *data)
  {
  	int ret;
  
  	ret = regmap_update_bits(data->regmap, RPR0521_REG_MODE_CTRL,
  				 RPR0521_MODE_ALS_MASK |
  				 RPR0521_MODE_PXS_MASK,
  				 RPR0521_MODE_ALS_DISABLE |
  				 RPR0521_MODE_PXS_DISABLE);
  	if (ret < 0)
  		return ret;
  
  	data->als_dev_en = false;
  	data->pxs_dev_en = false;
  
  	return 0;
  }
  
  static bool rpr0521_is_volatile_reg(struct device *dev, unsigned int reg)
  {
  	switch (reg) {
  	case RPR0521_REG_MODE_CTRL:
  	case RPR0521_REG_ALS_CTRL:
  	case RPR0521_REG_PXS_CTRL:
  		return false;
  	default:
  		return true;
  	}
  }
  
  static const struct regmap_config rpr0521_regmap_config = {
  	.name		= RPR0521_REGMAP_NAME,
  
  	.reg_bits	= 8,
  	.val_bits	= 8,
  
  	.max_register	= RPR0521_REG_ID,
  	.cache_type	= REGCACHE_RBTREE,
  	.volatile_reg	= rpr0521_is_volatile_reg,
  };
  
  static int rpr0521_probe(struct i2c_client *client,
  			 const struct i2c_device_id *id)
  {
  	struct rpr0521_data *data;
  	struct iio_dev *indio_dev;
  	struct regmap *regmap;
  	int ret;
  
  	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
  	if (!indio_dev)
  		return -ENOMEM;
  
  	regmap = devm_regmap_init_i2c(client, &rpr0521_regmap_config);
  	if (IS_ERR(regmap)) {
  		dev_err(&client->dev, "regmap_init failed!
  ");
  		return PTR_ERR(regmap);
  	}
  
  	data = iio_priv(indio_dev);
  	i2c_set_clientdata(client, indio_dev);
  	data->client = client;
  	data->regmap = regmap;
  
  	mutex_init(&data->lock);
  
  	indio_dev->dev.parent = &client->dev;
  	indio_dev->info = &rpr0521_info;
  	indio_dev->name = RPR0521_DRV_NAME;
  	indio_dev->channels = rpr0521_channels;
  	indio_dev->num_channels = ARRAY_SIZE(rpr0521_channels);
  	indio_dev->modes = INDIO_DIRECT_MODE;
  
  	ret = rpr0521_init(data);
  	if (ret < 0) {
  		dev_err(&client->dev, "rpr0521 chip init failed
  ");
  		return ret;
  	}
  	ret = iio_device_register(indio_dev);
  	if (ret < 0)
  		return ret;
  
  	ret = pm_runtime_set_active(&client->dev);
  	if (ret < 0)
  		goto err_iio_unregister;
  
  	pm_runtime_enable(&client->dev);
  	pm_runtime_set_autosuspend_delay(&client->dev, RPR0521_SLEEP_DELAY_MS);
  	pm_runtime_use_autosuspend(&client->dev);
  
  	return 0;
  
  err_iio_unregister:
  	iio_device_unregister(indio_dev);
  	return ret;
  }
  
  static int rpr0521_remove(struct i2c_client *client)
  {
  	struct iio_dev *indio_dev = i2c_get_clientdata(client);
  
  	pm_runtime_disable(&client->dev);
  	pm_runtime_set_suspended(&client->dev);
  	pm_runtime_put_noidle(&client->dev);
  
  	iio_device_unregister(indio_dev);
  	rpr0521_poweroff(iio_priv(indio_dev));
  
  	return 0;
  }
  
  #ifdef CONFIG_PM
  static int rpr0521_runtime_suspend(struct device *dev)
  {
  	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
  	struct rpr0521_data *data = iio_priv(indio_dev);
  	int ret;
  
  	/* disable channels and sets {als,pxs}_dev_en to false */
  	mutex_lock(&data->lock);
  	ret = rpr0521_poweroff(data);
  	mutex_unlock(&data->lock);
  
  	return ret;
  }
  
  static int rpr0521_runtime_resume(struct device *dev)
  {
  	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
  	struct rpr0521_data *data = iio_priv(indio_dev);
  	int ret;
  
  	if (data->als_ps_need_en) {
  		ret = rpr0521_als_enable(data, RPR0521_MODE_ALS_ENABLE);
  		if (ret < 0)
  			return ret;
  		data->als_ps_need_en = false;
  	}
  
  	if (data->pxs_ps_need_en) {
  		ret = rpr0521_pxs_enable(data, RPR0521_MODE_PXS_ENABLE);
  		if (ret < 0)
  			return ret;
  		data->pxs_ps_need_en = false;
  	}
  
  	return 0;
  }
  #endif
  
  static const struct dev_pm_ops rpr0521_pm_ops = {
  	SET_RUNTIME_PM_OPS(rpr0521_runtime_suspend,
  			   rpr0521_runtime_resume, NULL)
  };
  
  static const struct acpi_device_id rpr0521_acpi_match[] = {
  	{"RPR0521", 0},
  	{ }
  };
  MODULE_DEVICE_TABLE(acpi, rpr0521_acpi_match);
  
  static const struct i2c_device_id rpr0521_id[] = {
  	{"rpr0521", 0},
  	{ }
  };
  
  MODULE_DEVICE_TABLE(i2c, rpr0521_id);
  
  static struct i2c_driver rpr0521_driver = {
  	.driver = {
  		.name	= RPR0521_DRV_NAME,
  		.pm	= &rpr0521_pm_ops,
  		.acpi_match_table = ACPI_PTR(rpr0521_acpi_match),
  	},
  	.probe		= rpr0521_probe,
  	.remove		= rpr0521_remove,
  	.id_table	= rpr0521_id,
  };
  
  module_i2c_driver(rpr0521_driver);
  
  MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
  MODULE_DESCRIPTION("RPR0521 ROHM Ambient Light and Proximity Sensor driver");
  MODULE_LICENSE("GPL v2");