/*
   *  tsl2550.c - Linux kernel modules for ambient light sensor
   *
   *  Copyright (C) 2007 Rodolfo Giometti <giometti@linux.it>
   *  Copyright (C) 2007 Eurotech S.p.A. <info@eurotech.it>
   *
   *  This program is free software; you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License as published by
   *  the Free Software Foundation; either version 2 of the License, or
   *  (at your option) any later version.
   *
   *  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, write to the Free Software
   *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   */
  
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/slab.h>
  #include <linux/i2c.h>
  #include <linux/mutex.h>

  
  #define TSL2550_DRV_NAME	"tsl2550"

  #define DRIVER_VERSION		"1.2"

  
  /*
   * Defines
   */
  
  #define TSL2550_POWER_DOWN		0x00
  #define TSL2550_POWER_UP		0x03
  #define TSL2550_STANDARD_RANGE		0x18
  #define TSL2550_EXTENDED_RANGE		0x1d
  #define TSL2550_READ_ADC0		0x43
  #define TSL2550_READ_ADC1		0x83
  
  /*
   * Structs
   */
  
  struct tsl2550_data {
  	struct i2c_client *client;
  	struct mutex update_lock;

  	unsigned int power_state:1;
  	unsigned int operating_mode:1;

  };
  
  /*
   * Global data
   */
  
  static const u8 TSL2550_MODE_RANGE[2] = {
  	TSL2550_STANDARD_RANGE, TSL2550_EXTENDED_RANGE,
  };
  
  /*
   * Management functions
   */
  
  static int tsl2550_set_operating_mode(struct i2c_client *client, int mode)
  {
  	struct tsl2550_data *data = i2c_get_clientdata(client);
  
  	int ret = i2c_smbus_write_byte(client, TSL2550_MODE_RANGE[mode]);
  
  	data->operating_mode = mode;
  
  	return ret;
  }
  
  static int tsl2550_set_power_state(struct i2c_client *client, int state)
  {
  	struct tsl2550_data *data = i2c_get_clientdata(client);
  	int ret;
  
  	if (state == 0)
  		ret = i2c_smbus_write_byte(client, TSL2550_POWER_DOWN);
  	else {
  		ret = i2c_smbus_write_byte(client, TSL2550_POWER_UP);
  
  		/* On power up we should reset operating mode also... */
  		tsl2550_set_operating_mode(client, data->operating_mode);
  	}
  
  	data->power_state = state;
  
  	return ret;
  }
  
  static int tsl2550_get_adc_value(struct i2c_client *client, u8 cmd)
  {

  	int ret;

  	ret = i2c_smbus_read_byte_data(client, cmd);
  	if (ret < 0)
  		return ret;

  	if (!(ret & 0x80))

  		return -EAGAIN;

  	return ret & 0x7f;	/* remove the "valid" bit */
  }
  
  /*
   * LUX calculation
   */
  
  #define	TSL2550_MAX_LUX		1846
  
  static const u8 ratio_lut[] = {
  	100, 100, 100, 100, 100, 100, 100, 100,
  	100, 100, 100, 100, 100, 100, 99, 99,
  	99, 99, 99, 99, 99, 99, 99, 99,
  	99, 99, 99, 98, 98, 98, 98, 98,
  	98, 98, 97, 97, 97, 97, 97, 96,
  	96, 96, 96, 95, 95, 95, 94, 94,
  	93, 93, 93, 92, 92, 91, 91, 90,
  	89, 89, 88, 87, 87, 86, 85, 84,
  	83, 82, 81, 80, 79, 78, 77, 75,
  	74, 73, 71, 69, 68, 66, 64, 62,
  	60, 58, 56, 54, 52, 49, 47, 44,
  	42, 41, 40, 40, 39, 39, 38, 38,
  	37, 37, 37, 36, 36, 36, 35, 35,
  	35, 35, 34, 34, 34, 34, 33, 33,
  	33, 33, 32, 32, 32, 32, 32, 31,
  	31, 31, 31, 31, 30, 30, 30, 30,
  	30,
  };
  
  static const u16 count_lut[] = {
  	0, 1, 2, 3, 4, 5, 6, 7,
  	8, 9, 10, 11, 12, 13, 14, 15,
  	16, 18, 20, 22, 24, 26, 28, 30,
  	32, 34, 36, 38, 40, 42, 44, 46,
  	49, 53, 57, 61, 65, 69, 73, 77,
  	81, 85, 89, 93, 97, 101, 105, 109,
  	115, 123, 131, 139, 147, 155, 163, 171,
  	179, 187, 195, 203, 211, 219, 227, 235,
  	247, 263, 279, 295, 311, 327, 343, 359,
  	375, 391, 407, 423, 439, 455, 471, 487,
  	511, 543, 575, 607, 639, 671, 703, 735,
  	767, 799, 831, 863, 895, 927, 959, 991,
  	1039, 1103, 1167, 1231, 1295, 1359, 1423, 1487,
  	1551, 1615, 1679, 1743, 1807, 1871, 1935, 1999,
  	2095, 2223, 2351, 2479, 2607, 2735, 2863, 2991,
  	3119, 3247, 3375, 3503, 3631, 3759, 3887, 4015,
  };
  
  /*
   * This function is described into Taos TSL2550 Designer's Notebook
   * pages 2, 3.
   */
  static int tsl2550_calculate_lux(u8 ch0, u8 ch1)
  {
  	unsigned int lux;
  
  	/* Look up count from channel values */
  	u16 c0 = count_lut[ch0];
  	u16 c1 = count_lut[ch1];
  
  	/*
  	 * Calculate ratio.
  	 * Note: the "128" is a scaling factor
  	 */
  	u8 r = 128;
  
  	/* Avoid division by 0 and count 1 cannot be greater than count 0 */

  	if (c1 <= c0)
  		if (c0) {
  			r = c1 * 128 / c0;
  
  			/* Calculate LUX */
  			lux = ((c0 - c1) * ratio_lut[r]) / 256;
  		} else
  			lux = 0;

  	else

  		return -EAGAIN;

  
  	/* LUX range check */
  	return lux > TSL2550_MAX_LUX ? TSL2550_MAX_LUX : lux;
  }
  
  /*
   * SysFS support
   */
  
  static ssize_t tsl2550_show_power_state(struct device *dev,
  		struct device_attribute *attr, char *buf)
  {
  	struct tsl2550_data *data = i2c_get_clientdata(to_i2c_client(dev));
  
  	return sprintf(buf, "%u
  ", data->power_state);
  }
  
  static ssize_t tsl2550_store_power_state(struct device *dev,
  		struct device_attribute *attr, const char *buf, size_t count)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct tsl2550_data *data = i2c_get_clientdata(client);
  	unsigned long val = simple_strtoul(buf, NULL, 10);
  	int ret;
  
  	if (val < 0 || val > 1)
  		return -EINVAL;
  
  	mutex_lock(&data->update_lock);
  	ret = tsl2550_set_power_state(client, val);
  	mutex_unlock(&data->update_lock);
  
  	if (ret < 0)
  		return ret;
  
  	return count;
  }
  
  static DEVICE_ATTR(power_state, S_IWUSR | S_IRUGO,
  		   tsl2550_show_power_state, tsl2550_store_power_state);
  
  static ssize_t tsl2550_show_operating_mode(struct device *dev,
  		struct device_attribute *attr, char *buf)
  {
  	struct tsl2550_data *data = i2c_get_clientdata(to_i2c_client(dev));
  
  	return sprintf(buf, "%u
  ", data->operating_mode);
  }
  
  static ssize_t tsl2550_store_operating_mode(struct device *dev,
  		struct device_attribute *attr, const char *buf, size_t count)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct tsl2550_data *data = i2c_get_clientdata(client);
  	unsigned long val = simple_strtoul(buf, NULL, 10);
  	int ret;
  
  	if (val < 0 || val > 1)
  		return -EINVAL;
  
  	if (data->power_state == 0)
  		return -EBUSY;
  
  	mutex_lock(&data->update_lock);
  	ret = tsl2550_set_operating_mode(client, val);
  	mutex_unlock(&data->update_lock);
  
  	if (ret < 0)
  		return ret;
  
  	return count;
  }
  
  static DEVICE_ATTR(operating_mode, S_IWUSR | S_IRUGO,
  		   tsl2550_show_operating_mode, tsl2550_store_operating_mode);
  
  static ssize_t __tsl2550_show_lux(struct i2c_client *client, char *buf)
  {

  	struct tsl2550_data *data = i2c_get_clientdata(client);

  	u8 ch0, ch1;
  	int ret;
  
  	ret = tsl2550_get_adc_value(client, TSL2550_READ_ADC0);
  	if (ret < 0)
  		return ret;
  	ch0 = ret;

  	ret = tsl2550_get_adc_value(client, TSL2550_READ_ADC1);
  	if (ret < 0)
  		return ret;
  	ch1 = ret;
  
  	/* Do the job */
  	ret = tsl2550_calculate_lux(ch0, ch1);
  	if (ret < 0)
  		return ret;

  	if (data->operating_mode == 1)
  		ret *= 5;

  
  	return sprintf(buf, "%d
  ", ret);
  }
  
  static ssize_t tsl2550_show_lux1_input(struct device *dev,
  			struct device_attribute *attr, char *buf)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct tsl2550_data *data = i2c_get_clientdata(client);
  	int ret;
  
  	/* No LUX data if not operational */
  	if (!data->power_state)
  		return -EBUSY;
  
  	mutex_lock(&data->update_lock);
  	ret = __tsl2550_show_lux(client, buf);
  	mutex_unlock(&data->update_lock);
  
  	return ret;
  }
  
  static DEVICE_ATTR(lux1_input, S_IRUGO,
  		   tsl2550_show_lux1_input, NULL);
  
  static struct attribute *tsl2550_attributes[] = {
  	&dev_attr_power_state.attr,
  	&dev_attr_operating_mode.attr,
  	&dev_attr_lux1_input.attr,
  	NULL
  };
  
  static const struct attribute_group tsl2550_attr_group = {
  	.attrs = tsl2550_attributes,
  };
  
  /*
   * Initialization function
   */

  static int tsl2550_init_client(struct i2c_client *client)

  {
  	struct tsl2550_data *data = i2c_get_clientdata(client);

  	int err;

  	/*
  	 * Probe the chip. To do so we try to power up the device and then to
  	 * read back the 0x03 code
  	 */

  	err = i2c_smbus_read_byte_data(client, TSL2550_POWER_UP);

  	if (err < 0)
  		return err;

  	if (err != TSL2550_POWER_UP)

  		return -ENODEV;
  	data->power_state = 1;
  
  	/* Set the default operating mode */
  	err = i2c_smbus_write_byte(client,
  				   TSL2550_MODE_RANGE[data->operating_mode]);
  	if (err < 0)
  		return err;
  
  	return 0;

  }
  
  /*
   * I2C init/probing/exit functions
   */
  
  static struct i2c_driver tsl2550_driver;

  static int __devinit tsl2550_probe(struct i2c_client *client,
  				   const struct i2c_device_id *id)

  {
  	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
  	struct tsl2550_data *data;
  	int *opmode, err = 0;

  	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WRITE_BYTE
  					    | I2C_FUNC_SMBUS_READ_BYTE_DATA)) {

  		err = -EIO;
  		goto exit;
  	}
  
  	data = kzalloc(sizeof(struct tsl2550_data), GFP_KERNEL);
  	if (!data) {
  		err = -ENOMEM;
  		goto exit;
  	}
  	data->client = client;
  	i2c_set_clientdata(client, data);
  
  	/* Check platform data */
  	opmode = client->dev.platform_data;
  	if (opmode) {
  		if (*opmode < 0 || *opmode > 1) {
  			dev_err(&client->dev, "invalid operating_mode (%d)
  ",
  					*opmode);
  			err = -EINVAL;
  			goto exit_kfree;
  		}
  		data->operating_mode = *opmode;
  	} else
  		data->operating_mode = 0;	/* default mode is standard */
  	dev_info(&client->dev, "%s operating mode
  ",
  			data->operating_mode ? "extended" : "standard");

  	mutex_init(&data->update_lock);
  
  	/* Initialize the TSL2550 chip */

  	err = tsl2550_init_client(client);
  	if (err)
  		goto exit_kfree;

  
  	/* Register sysfs hooks */
  	err = sysfs_create_group(&client->dev.kobj, &tsl2550_attr_group);
  	if (err)
  		goto exit_kfree;
  
  	dev_info(&client->dev, "support ver. %s enabled
  ", DRIVER_VERSION);
  
  	return 0;
  
  exit_kfree:
  	kfree(data);
  exit:
  	return err;
  }
  
  static int __devexit tsl2550_remove(struct i2c_client *client)
  {
  	sysfs_remove_group(&client->dev.kobj, &tsl2550_attr_group);
  
  	/* Power down the device */
  	tsl2550_set_power_state(client, 0);
  
  	kfree(i2c_get_clientdata(client));
  
  	return 0;
  }

  #ifdef CONFIG_PM
  
  static int tsl2550_suspend(struct i2c_client *client, pm_message_t mesg)
  {
  	return tsl2550_set_power_state(client, 0);
  }
  
  static int tsl2550_resume(struct i2c_client *client)
  {
  	return tsl2550_set_power_state(client, 1);
  }
  
  #else
  
  #define tsl2550_suspend		NULL
  #define tsl2550_resume		NULL
  
  #endif /* CONFIG_PM */

  static const struct i2c_device_id tsl2550_id[] = {
  	{ "tsl2550", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, tsl2550_id);

  static struct i2c_driver tsl2550_driver = {
  	.driver = {
  		.name	= TSL2550_DRV_NAME,
  		.owner	= THIS_MODULE,
  	},

  	.suspend = tsl2550_suspend,
  	.resume	= tsl2550_resume,

  	.probe	= tsl2550_probe,
  	.remove	= __devexit_p(tsl2550_remove),

  	.id_table = tsl2550_id,

  };
  
  static int __init tsl2550_init(void)
  {
  	return i2c_add_driver(&tsl2550_driver);
  }
  
  static void __exit tsl2550_exit(void)
  {
  	i2c_del_driver(&tsl2550_driver);
  }
  
  MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
  MODULE_DESCRIPTION("TSL2550 ambient light sensor driver");
  MODULE_LICENSE("GPL");

  MODULE_VERSION(DRIVER_VERSION);

  
  module_init(tsl2550_init);
  module_exit(tsl2550_exit);