zfs: Add ZFS filesystem support

U-Boot port is based on sources forked from GRUB-0.97 by Sun in 2004,
which can be found here:
http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/grub/grub-0.97/stage2/zfs-include/zfs.h

Released by Sun for GRUB under the license:
  *  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.

GRUB official releases include ZFS in version:
ftp://alpha.gnu.org/gnu/grub/grub-1.99~rc1.tar.gz

And patched against GRUB Bazaar repository for ashift fixes (4KB HDDs)
more conveniently found at github:
https://github.com/pendor/grub-zfs/commit/e7b6ef3ac3b9685ac4c394c897b1d4221b7381f1

Signed-off-by: Jorgen Lundman <lundman@lundman.net>
diff --git a/include/zfs/zio_checksum.h b/include/zfs/zio_checksum.h
new file mode 100644
index 0000000..0d5fce6
--- /dev/null
+++ b/include/zfs/zio_checksum.h
@@ -0,0 +1,50 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 1999,2000,2001,2002,2003,2004  Free Software Foundation, Inc.
+ *
+ *  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.
+ */
+/*
+ * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#ifndef _SYS_ZIO_CHECKSUM_H
+#define	_SYS_ZIO_CHECKSUM_H
+
+/*
+ * Signature for checksum functions.
+ */
+typedef void zio_checksum_t(const void *data, uint64_t size,
+			    zfs_endian_t endian, zio_cksum_t *zcp);
+
+/*
+ * Information about each checksum function.
+ */
+typedef struct zio_checksum_info {
+	zio_checksum_t	*ci_func; /* checksum function for each byteorder */
+	int		ci_correctable;	/* number of correctable bits	*/
+	int		ci_eck;		/* uses zio embedded checksum? */
+	char		*ci_name;	/* descriptive name */
+} zio_checksum_info_t;
+
+extern void zio_checksum_SHA256(const void *, uint64_t,
+				 zfs_endian_t endian, zio_cksum_t *);
+extern void fletcher_2_endian(const void *, uint64_t, zfs_endian_t endian,
+			zio_cksum_t *);
+extern void fletcher_4_endian(const void *, uint64_t, zfs_endian_t endian,
+			zio_cksum_t *);
+
+#endif	/* _SYS_ZIO_CHECKSUM_H */