[PATCH] I2C: add i2c sensor_device_attribute and macros

This patch creates a new header with a potential standard i2c sensor
attribute type (which simply includes an int representing the sensor
number/index) and the associated macros, SENSOR_DEVICE_ATTR to define
a static attribute and to_sensor_dev_attr to get a
sensor_device_attribute reference from an embedded device_attribute
reference.
Signed-off-by: Yani Ioannou <yani.ioannou@gmail.com>

include/linux/i2c-sysfs.h

+/*
+ *  i2c-sysfs.h - i2c chip driver sysfs defines
+ *
+ *  Copyright (C) 2005 Yani Ioannou <yani.ioannou@gmail.com>
+ *
+ *  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.
+ */
+#ifndef _LINUX_I2C_SYSFS_H
+#define _LINUX_I2C_SYSFS_H
+
+struct sensor_device_attribute{
+	struct device_attribute dev_attr;
+	int index;
+};
+#define to_sensor_dev_attr(_dev_attr) \
+	container_of(_dev_attr, struct sensor_device_attribute, dev_attr)
+
+#define SENSOR_DEVICE_ATTR(_name,_mode,_show,_store,_index)	\
+struct sensor_device_attribute sensor_dev_attr_##_name = {	\
+	.dev_attr =	__ATTR(_name,_mode,_show,_store),	\
+	.index =	_index,					\
+}
+
+#endif /* _LINUX_I2C_SYSFS_H */