fs: jffs2: add initial support for reading jffs2

Import the jffs2 filesystem code from Linux v5.5-rc1 and convert it
to work with barebox.

Writing is *not* supported.

Testing was done with a n25q256a-compatible QuadSPI chip on a
SoCFPGA-based Socrates board.

Testing was done with a combination of:
	user@somelinuxhost: mkfs.jffs2 --eraseblock=4 -d fs/jffs2/ -o jffs2.img
	root@target:~ flash_erase -j /dev/mtd5 0 0
	root@target:~ dd if=jffs2.img of=/dev/mtd5
	barebox@EBV SOCrates:/ mount /dev/mtd0.data
	(...)
	mounted /dev/mtd0.data on /mnt/mtd0.data

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 52 insertions, 0 deletions

diff --git a/fs/jffs2/compr_lzo.c b/fs/jffs2/compr_lzo.c
new file mode 100644
index 0000000000..1be30dc604
--- /dev/null
+++ b/fs/jffs2/compr_lzo.c
@@ -0,0 +1,52 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright © 2007 Nokia Corporation. All rights reserved.
+ * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
+ *
+ * Created by Richard Purdie <rpurdie@openedhand.com>
+ *
+ * For licensing information, see the file 'LICENCE' in this directory.
+ *
+ */
+
+#include <common.h>
+#include <lzo.h>
+#include <linux/kernel.h>
+#include "compr.h"
+
+static int jffs2_lzo_decompress(unsigned char *data_in, unsigned char *cpage_out,
+				 uint32_t srclen, uint32_t destlen)
+{
+	size_t dl = destlen;
+	int ret;
+
+	ret = lzo1x_decompress_safe(data_in, srclen, cpage_out, &dl);
+
+	if (ret != LZO_E_OK || dl != destlen)
+		return -1;
+
+	return 0;
+}
+
+static struct jffs2_compressor jffs2_lzo_comp = {
+	.priority = JFFS2_LZO_PRIORITY,
+	.name = "lzo",
+	.compr = JFFS2_COMPR_LZO,
+	.decompress = &jffs2_lzo_decompress,
+	.disabled = 0,
+};
+
+int __init jffs2_lzo_init(void)
+{
+	int ret;
+
+	ret = jffs2_register_compressor(&jffs2_lzo_comp);
+
+	return ret;
+}
+
+void jffs2_lzo_exit(void)
+{
+	jffs2_unregister_compressor(&jffs2_lzo_comp);
+}