iio: core: Introduce IIO_EV_DIR_NONE

For some events (e.g.: step detector) a direction does not make sense.

Add IIO_EV_DIR_NONE to be used with such events and generate sysfs event
attributes that do not contain direction.

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/industrialio-event.c

@@ -327,8 +327,14 @@ static int iio_device_add_event(struct iio_dev *indio_dev,
 	for_each_set_bit(i, mask, sizeof(*mask)*8) {
 		if (i >= ARRAY_SIZE(iio_ev_info_text))
 			return -EINVAL;
+		if (dir != IIO_EV_DIR_NONE)
 			postfix = kasprintf(GFP_KERNEL, "%s_%s_%s",
-				iio_ev_type_text[type], iio_ev_dir_text[dir],
+					iio_ev_type_text[type],
+					iio_ev_dir_text[dir],
+					iio_ev_info_text[i]);
+		else
+			postfix = kasprintf(GFP_KERNEL, "%s_%s",
+					iio_ev_type_text[type],
 					iio_ev_info_text[i]);
 		if (postfix == NULL)
 			return -ENOMEM;

include/linux/iio/types.h

@@ -86,6 +86,7 @@ enum iio_event_direction {
 	IIO_EV_DIR_EITHER,
 	IIO_EV_DIR_RISING,
 	IIO_EV_DIR_FALLING,
+	IIO_EV_DIR_NONE,
 };
 
 #define IIO_VAL_INT 1