From da4458bda237aa0cb1688f6c359477f203788f6a Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 12 Feb 2009 10:40:10 +0000 Subject: NOMMU: Make it possible for RomFS to use MTD devices directly Change RomFS so that it can use MTD devices directly - without the intercession of the block layer - as well as using block devices. This permits RomFS: (1) to use the MTD direct mapping facility available under NOMMU conditions if the underlying device is directly accessible by the CPU (including XIP); (2) and thus to be used when the block layer is disabled. RomFS can be configured with support just for MTD devices, just for Block devices or for both. If RomFS is configured for both, then it will treat mtdblock device files as MTD backing stores, not block layer backing stores. I tested this using a CONFIG_MMU=n CONFIG_BLOCK=n kernel running on my FRV board with a RomFS image installed on the mtdram test device. I see my test program being run XIP: # cat /proc/maps ... c0c000b0-c0c01f8c r-xs 00000000 1f:00 144 /mnt/doshm ... GDB on the kernel can be used to show that these addresses are within the set-aside RAM space. Signed-off-by: David Howells Tested-by: Bernd Schmidt Signed-off-by: David Woodhouse --- fs/romfs/internal.h | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 fs/romfs/internal.h (limited to 'fs/romfs/internal.h') diff --git a/fs/romfs/internal.h b/fs/romfs/internal.h new file mode 100644 index 000000000000..06044a9dc62d --- /dev/null +++ b/fs/romfs/internal.h @@ -0,0 +1,47 @@ +/* RomFS internal definitions + * + * Copyright © 2007 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * 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. + */ + +#include + +struct romfs_inode_info { + struct inode vfs_inode; + unsigned long i_metasize; /* size of non-data area */ + unsigned long i_dataoffset; /* from the start of fs */ +}; + +static inline size_t romfs_maxsize(struct super_block *sb) +{ + return (size_t) (unsigned long) sb->s_fs_info; +} + +static inline struct romfs_inode_info *ROMFS_I(struct inode *inode) +{ + return container_of(inode, struct romfs_inode_info, vfs_inode); +} + +/* + * mmap-nommu.c + */ +#if !defined(CONFIG_MMU) && defined(CONFIG_ROMFS_ON_MTD) +extern const struct file_operations romfs_ro_fops; +#else +#define romfs_ro_fops generic_ro_fops +#endif + +/* + * storage.c + */ +extern int romfs_dev_read(struct super_block *sb, unsigned long pos, + void *buf, size_t buflen); +extern ssize_t romfs_dev_strnlen(struct super_block *sb, + unsigned long pos, size_t maxlen); +extern int romfs_dev_strncmp(struct super_block *sb, unsigned long pos, + const char *str, size_t size); -- cgit v1.2.2