include: linux: iio: add IIO_ATTR_{RO, WO, RW} and IIO_DEVICE_ATTR_{RO, WO, RW} macros

Add new macros: IIO_ATTR_RO, IIO_ATTR_WO, IIO_ATTR_RW,
IIO_DEVICE_ATTR_RO, IIO_DEVICE_ATTR_WO and IIO_DEVICE_ATTR_RW to reduce
the amount of boiler plate code that is needed for creating new
attributes. This mimics the *_RO, *_WO, and *_RW macros that are found
in include/linux/device.h and include/linux/sysfs.h.

Signed-off-by: Brian Masney <masneyb@onstation.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

include/linux/iio/sysfs.h

@@ -55,10 +55,34 @@ struct iio_const_attr {
 	{ .dev_attr = __ATTR(_name, _mode, _show, _store),	\
 	  .address = _addr }
 
+#define IIO_ATTR_RO(_name, _addr)       \
+	{ .dev_attr = __ATTR_RO(_name), \
+	  .address = _addr }
+
+#define IIO_ATTR_WO(_name, _addr)       \
+	{ .dev_attr = __ATTR_WO(_name), \
+	  .address = _addr }
+
+#define IIO_ATTR_RW(_name, _addr)       \
+	{ .dev_attr = __ATTR_RW(_name), \
+	  .address = _addr }
+
 #define IIO_DEVICE_ATTR(_name, _mode, _show, _store, _addr)	\
 	struct iio_dev_attr iio_dev_attr_##_name		\
 	= IIO_ATTR(_name, _mode, _show, _store, _addr)
 
+#define IIO_DEVICE_ATTR_RO(_name, _addr)                       \
+	struct iio_dev_attr iio_dev_attr_##_name                \
+	= IIO_ATTR_RO(_name, _addr)
+
+#define IIO_DEVICE_ATTR_WO(_name, _addr)                       \
+	struct iio_dev_attr iio_dev_attr_##_name                \
+	= IIO_ATTR_WO(_name, _addr)
+
+#define IIO_DEVICE_ATTR_RW(_name, _addr)                                   \
+	struct iio_dev_attr iio_dev_attr_##_name                            \
+	= IIO_ATTR_RW(_name, _addr)
+
 #define IIO_DEVICE_ATTR_NAMED(_vname, _name, _mode, _show, _store, _addr) \
 	struct iio_dev_attr iio_dev_attr_##_vname			\
 	= IIO_ATTR(_name, _mode, _show, _store, _addr)