Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
index 9887f4f..2bde8c9 100644
--- a/include/linux/iio/consumer.h
+++ b/include/linux/iio/consumer.h
@@ -1,11 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
 /*
  * Industrial I/O in kernel consumer interface
  *
  * Copyright (c) 2011 Jonathan Cameron
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published by
- * the Free Software Foundation.
  */
 #ifndef _IIO_INKERN_CONSUMER_H_
 #define _IIO_INKERN_CONSUMER_H_
@@ -291,6 +288,20 @@
 			       const int **vals, int *length);
 
 /**
+ * iio_read_avail_channel_attribute() - read available channel attribute values
+ * @chan:		The channel being queried.
+ * @vals:		Available values read back.
+ * @type:		Type of values read back.
+ * @length:		Number of entries in vals.
+ * @attribute:		info attribute to be read back.
+ *
+ * Returns an error code, IIO_AVAIL_RANGE or IIO_AVAIL_LIST.
+ */
+int iio_read_avail_channel_attribute(struct iio_channel *chan,
+				     const int **vals, int *type, int *length,
+				     enum iio_chan_info_enum attribute);
+
+/**
  * iio_get_channel_type() - get the type of a channel
  * @channel:		The channel being queried.
  * @type:		The type of the channel.