drivers/misc/tsl2550.c - arm/linux - Git at Google

 /*
  *  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/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\n", 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 > 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\n", 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 > 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\n", 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 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)\n",
 					*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\n",
 			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\n", DRIVER_VERSION);

 	return 0;

 exit_kfree:
 	kfree(data);
 exit:
 	return err;
 }

 static int 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_SLEEP

 static int tsl2550_suspend(struct device *dev)
 {
 	return tsl2550_set_power_state(to_i2c_client(dev), 0);
 }

 static int tsl2550_resume(struct device *dev)
 {
 	return tsl2550_set_power_state(to_i2c_client(dev), 1);
 }

 static SIMPLE_DEV_PM_OPS(tsl2550_pm_ops, tsl2550_suspend, tsl2550_resume);
 #define TSL2550_PM_OPS (&tsl2550_pm_ops)

 #else

 #define TSL2550_PM_OPS NULL

 #endif /* CONFIG_PM_SLEEP */

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

 static const struct of_device_id tsl2550_of_match[] = {
 	{ .compatible = "taos,tsl2550" },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, tsl2550_of_match);

 static struct i2c_driver tsl2550_driver = {
 	.driver = {
 		.name	= TSL2550_DRV_NAME,
 		.of_match_table = tsl2550_of_match,
 		.pm	= TSL2550_PM_OPS,
 	},
 	.probe	= tsl2550_probe,
 	.remove	= tsl2550_remove,
 	.id_table = tsl2550_id,
 };

 module_i2c_driver(tsl2550_driver);

 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
 MODULE_DESCRIPTION("TSL2550 ambient light sensor driver");
 MODULE_LICENSE("GPL");
 MODULE_VERSION(DRIVER_VERSION);
	/*
	* 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/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\n", 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 > 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\n", 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 > 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\n", 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 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)\n",
	*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\n",
	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\n", DRIVER_VERSION);

	return 0;

	exit_kfree:
	kfree(data);
	exit:
	return err;
	}

	static int 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_SLEEP

	static int tsl2550_suspend(struct device *dev)
	{
	return tsl2550_set_power_state(to_i2c_client(dev), 0);
	}

	static int tsl2550_resume(struct device *dev)
	{
	return tsl2550_set_power_state(to_i2c_client(dev), 1);
	}

	static SIMPLE_DEV_PM_OPS(tsl2550_pm_ops, tsl2550_suspend, tsl2550_resume);
	#define TSL2550_PM_OPS (&tsl2550_pm_ops)

	#else

	#define TSL2550_PM_OPS NULL

	#endif /* CONFIG_PM_SLEEP */

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

	static const struct of_device_id tsl2550_of_match[] = {
	{ .compatible = "taos,tsl2550" },
	{ }
	};
	MODULE_DEVICE_TABLE(of, tsl2550_of_match);

	static struct i2c_driver tsl2550_driver = {
	.driver = {
	.name = TSL2550_DRV_NAME,
	.of_match_table = tsl2550_of_match,
	.pm = TSL2550_PM_OPS,
	},
	.probe = tsl2550_probe,
	.remove = tsl2550_remove,
	.id_table = tsl2550_id,
	};

	module_i2c_driver(tsl2550_driver);

	MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
	MODULE_DESCRIPTION("TSL2550 ambient light sensor driver");
	MODULE_LICENSE("GPL");
	MODULE_VERSION(DRIVER_VERSION);