/*
   * bh1780gli.c
   * ROHM Ambient Light Sensor Driver
   *
   * Copyright (C) 2010 Texas Instruments
   * Author: Hemanth V <hemanthv@ti.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.
   *
   * This program is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
   * more details.
   *
   * You should have received a copy of the GNU General Public License along with
   * this program.  If not, see <http://www.gnu.org/licenses/>.
   */
  #include <linux/i2c.h>
  #include <linux/slab.h>
  #include <linux/mutex.h>
  #include <linux/platform_device.h>
  #include <linux/delay.h>
  #include <linux/module.h>
  #include <linux/of.h>
  
  #define BH1780_REG_CONTROL	0x80
  #define BH1780_REG_PARTID	0x8A
  #define BH1780_REG_MANFID	0x8B
  #define BH1780_REG_DLOW	0x8C
  #define BH1780_REG_DHIGH	0x8D
  
  #define BH1780_REVMASK		(0xf)
  #define BH1780_POWMASK		(0x3)
  #define BH1780_POFF		(0x0)
  #define BH1780_PON		(0x3)
  
  /* power on settling time in ms */
  #define BH1780_PON_DELAY	2
  
  struct bh1780_data {
  	struct i2c_client *client;
  	int power_state;
  	/* lock for sysfs operations */
  	struct mutex lock;
  };
  
  static int bh1780_write(struct bh1780_data *ddata, u8 reg, u8 val, char *msg)
  {
  	int ret = i2c_smbus_write_byte_data(ddata->client, reg, val);
  	if (ret < 0)
  		dev_err(&ddata->client->dev,
  			"i2c_smbus_write_byte_data failed error %d Register (%s)
  ",
  			ret, msg);
  	return ret;
  }
  
  static int bh1780_read(struct bh1780_data *ddata, u8 reg, char *msg)
  {
  	int ret = i2c_smbus_read_byte_data(ddata->client, reg);
  	if (ret < 0)
  		dev_err(&ddata->client->dev,
  			"i2c_smbus_read_byte_data failed error %d Register (%s)
  ",
  			ret, msg);
  	return ret;
  }
  
  static ssize_t bh1780_show_lux(struct device *dev,
  				struct device_attribute *attr, char *buf)
  {
  	struct platform_device *pdev = to_platform_device(dev);
  	struct bh1780_data *ddata = platform_get_drvdata(pdev);
  	int lsb, msb;
  
  	lsb = bh1780_read(ddata, BH1780_REG_DLOW, "DLOW");
  	if (lsb < 0)
  		return lsb;
  
  	msb = bh1780_read(ddata, BH1780_REG_DHIGH, "DHIGH");
  	if (msb < 0)
  		return msb;
  
  	return sprintf(buf, "%d
  ", (msb << 8) | lsb);
  }
  
  static ssize_t bh1780_show_power_state(struct device *dev,
  					struct device_attribute *attr,
  					char *buf)
  {
  	struct platform_device *pdev = to_platform_device(dev);
  	struct bh1780_data *ddata = platform_get_drvdata(pdev);
  	int state;
  
  	state = bh1780_read(ddata, BH1780_REG_CONTROL, "CONTROL");
  	if (state < 0)
  		return state;
  
  	return sprintf(buf, "%d
  ", state & BH1780_POWMASK);
  }
  
  static ssize_t bh1780_store_power_state(struct device *dev,
  					struct device_attribute *attr,
  					const char *buf, size_t count)
  {
  	struct platform_device *pdev = to_platform_device(dev);
  	struct bh1780_data *ddata = platform_get_drvdata(pdev);
  	unsigned long val;
  	int error;
  
  	error = kstrtoul(buf, 0, &val);
  	if (error)
  		return error;
  
  	if (val < BH1780_POFF || val > BH1780_PON)
  		return -EINVAL;
  
  	mutex_lock(&ddata->lock);
  
  	error = bh1780_write(ddata, BH1780_REG_CONTROL, val, "CONTROL");
  	if (error < 0) {
  		mutex_unlock(&ddata->lock);
  		return error;
  	}
  
  	msleep(BH1780_PON_DELAY);
  	ddata->power_state = val;
  	mutex_unlock(&ddata->lock);
  
  	return count;
  }
  
  static DEVICE_ATTR(lux, S_IRUGO, bh1780_show_lux, NULL);
  
  static DEVICE_ATTR(power_state, S_IWUSR | S_IRUGO,
  		bh1780_show_power_state, bh1780_store_power_state);
  
  static struct attribute *bh1780_attributes[] = {
  	&dev_attr_power_state.attr,
  	&dev_attr_lux.attr,
  	NULL
  };
  
  static const struct attribute_group bh1780_attr_group = {
  	.attrs = bh1780_attributes,
  };
  
  static int bh1780_probe(struct i2c_client *client,
  						const struct i2c_device_id *id)
  {
  	int ret;
  	struct bh1780_data *ddata = NULL;
  	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
  
  	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE)) {
  		ret = -EIO;
  		goto err_op_failed;
  	}
  
  	ddata = kzalloc(sizeof(struct bh1780_data), GFP_KERNEL);
  	if (ddata == NULL) {
  		ret = -ENOMEM;
  		goto err_op_failed;
  	}
  
  	ddata->client = client;
  	i2c_set_clientdata(client, ddata);
  
  	ret = bh1780_read(ddata, BH1780_REG_PARTID, "PART ID");
  	if (ret < 0)
  		goto err_op_failed;
  
  	dev_info(&client->dev, "Ambient Light Sensor, Rev : %d
  ",
  			(ret & BH1780_REVMASK));
  
  	mutex_init(&ddata->lock);
  
  	ret = sysfs_create_group(&client->dev.kobj, &bh1780_attr_group);
  	if (ret)
  		goto err_op_failed;
  
  	return 0;
  
  err_op_failed:
  	kfree(ddata);
  	return ret;
  }
  
  static int bh1780_remove(struct i2c_client *client)
  {
  	struct bh1780_data *ddata;
  
  	ddata = i2c_get_clientdata(client);
  	sysfs_remove_group(&client->dev.kobj, &bh1780_attr_group);
  	kfree(ddata);
  
  	return 0;
  }
  
  #ifdef CONFIG_PM_SLEEP
  static int bh1780_suspend(struct device *dev)
  {
  	struct bh1780_data *ddata;
  	int state, ret;
  	struct i2c_client *client = to_i2c_client(dev);
  
  	ddata = i2c_get_clientdata(client);
  	state = bh1780_read(ddata, BH1780_REG_CONTROL, "CONTROL");
  	if (state < 0)
  		return state;
  
  	ddata->power_state = state & BH1780_POWMASK;
  
  	ret = bh1780_write(ddata, BH1780_REG_CONTROL, BH1780_POFF,
  				"CONTROL");
  
  	if (ret < 0)
  		return ret;
  
  	return 0;
  }
  
  static int bh1780_resume(struct device *dev)
  {
  	struct bh1780_data *ddata;
  	int state, ret;
  	struct i2c_client *client = to_i2c_client(dev);
  
  	ddata = i2c_get_clientdata(client);
  	state = ddata->power_state;
  	ret = bh1780_write(ddata, BH1780_REG_CONTROL, state,
  				"CONTROL");
  
  	if (ret < 0)
  		return ret;
  
  	return 0;
  }
  #endif /* CONFIG_PM_SLEEP */
  
  static SIMPLE_DEV_PM_OPS(bh1780_pm, bh1780_suspend, bh1780_resume);
  
  static const struct i2c_device_id bh1780_id[] = {
  	{ "bh1780", 0 },
  	{ },
  };
  
  #ifdef CONFIG_OF
  static const struct of_device_id of_bh1780_match[] = {
  	{ .compatible = "rohm,bh1780gli", },
  	{},
  };
  
  MODULE_DEVICE_TABLE(of, of_bh1780_match);
  #endif
  
  static struct i2c_driver bh1780_driver = {
  	.probe		= bh1780_probe,
  	.remove		= bh1780_remove,
  	.id_table	= bh1780_id,
  	.driver = {
  		.name = "bh1780",
  		.pm	= &bh1780_pm,
  		.of_match_table = of_match_ptr(of_bh1780_match),
  	},
  };
  
  module_i2c_driver(bh1780_driver);
  
  MODULE_DESCRIPTION("BH1780GLI Ambient Light Sensor Driver");
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Hemanth V <hemanthv@ti.com>");